顔写真

タキザワ ヒロツグ
滝澤 博胤
Hirotsugu Takizawa
所属
役員
職名
理事
学位
  • 工学博士(東北大学)

e-Rad 研究者番号
90226960

経歴 6

  • 2004年4月 ~ 継続中
    東北大学大学院工学研究科 教授

  • 1997年4月 ~ 2004年3月
    東北大学大学院工学研究科 助教授

  • 1995年4月 ~ 1997年3月
    東北大学工学部 助教授

  • 1994年7月 ~ 1995年4月
    テキサス大学オースチン校 客員研究員

  • 1993年8月 ~ 1995年3月
    東北大学素材工学研究所 助手

  • 1990年4月 ~ 1993年7月
    東北大学工学部 助手

︎全件表示 ︎最初の5件までを表示

学歴 2

  • 東北大学 工学研究科 材料化学専攻

    ~ 1990年3月

  • 東北大学 工学部 応用化学

    ~ 1985年3月

委員歴 20

  • The Society of Inorganic Materials, Japan Board member

    2003年4月 ~ 継続中

  • 無機マテリアル学会 評議員

    2003年4月 ~ 継続中

  • 日本電磁波エネルギー応用学会 理事長

    2015年6月 ~ 2018年5月

  • 日本電磁波エネルギー応用学会 理事

    2007年6月 ~ 2015年5月

  • The Japan Society of High Pressure Science and Technology Board member

    2005年9月 ~ 2007年9月

  • The Japan Society of High Pressure Science and Technology 企画幹事

    2005年9月 ~ 2007年9月

  • 日本高圧力学会 評議員

    2005年9月 ~ 2007年9月

  • 日本高圧力学会 企画幹事

    2005年9月 ~ 2007年9月

  • The Chemical Society of Japan 代議員

    2005年11月 ~ 2006年11月

  • 日本化学会 代議員

    2005年11月 ~ 2006年11月

  • The Chemical Society of Japan Editor

    2003年3月 ~ 2005年3月

  • 日本化学会 化工誌編集委員

    2003年3月 ~ 2005年3月

  • The Japan Society of High Pressure Science and Technology Board member

    2002年9月 ~ 2004年9月

  • 日本高圧力学会 評議員

    2002年9月 ~ 2004年9月

  • The Ceramics Society of Japan Editor

    2002年4月 ~ 2004年3月

  • 日本セラミックス協会 学術論文誌編集委員

    2002年4月 ~ 2004年3月

  • The Ceramics Society of Japan Editor, Ceramics Japan

    1997年4月 ~ 1999年3月

  • 日本セラミックス協会 セラミックス編集委員

    1997年4月 ~ 1999年3月

  • The Ceramics Society of Japan 基礎科学部会幹事

    1996年10月 ~ 1998年9月

  • 日本セラミックス協会 基礎科学部会幹事

    1996年10月 ~ 1998年9月

︎全件表示 ︎最初の5件までを表示

所属学協会 8

  • 日本電磁波エネルギー応用学会

  • 無機マテリアル学会

  • 粉体粉末冶金協会

  • 米国材料学会

  • 米国セラミックス協会

  • 日本高圧力学会

  • 日本化学会

  • 日本セラミックス協会

︎全件表示 ︎最初の5件までを表示

研究キーワード 4

  • 結晶化学

  • 無機材料

  • 高圧合成

  • マイクロ波プロセッシング

研究分野 3

  • ナノテク・材料 / 構造材料、機能材料 /

  • ナノテク・材料 / 無機材料、物性 / 高圧合成

  • ナノテク・材料 / 無機物質、無機材料化学 / 固体化学

受賞 2

  1. 日本セラミックス協会学術賞

    2011年6月3日 公益社団法人日本セラミックス協会 超高圧力場・マイクロ波電磁場を反応場とした新材料創製の研究

  2. 日本高圧力学会奨励賞

    1996年11月19日 日本高圧力学会 超高圧合成法による新規遷移金属化合物の創製に関する研究

論文 252

  1. Green fabrication of unoxidized graphene by combination of frozen dispersion and multimode microwave thermal shock

    Yusuke Ebato, Yamato Hayashi, Hirotsugu Takizawa

    Cleaner Engineering and Technology 100681-100681 2023年10月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.clet.2023.100681  

    ISSN:2666-7908

  2. Synthesis of BaTiO3/Ag nanocomposites using a sonochemical process and low-temperature sintering 査読有り

    Hayashi Yamato, Shishido Tatsuya, Seki Kento, Takizawa Hirotsugu

    Journal of Asian Ceramic Societies 1-8 2023年8月

    出版者・発行元:None

    DOI: 10.1080/21870764.2023.2251243  

    eISSN:2187-0764

  3. Effect of redox potential of added metals and ultrasound irradiation on the oxidation behavior of gallium-based liquefied alloys 査読有り

    Toshiki Yamanaka, Yamato Hayashi, Hirotsugu Takizawa

    Journal of the Ceramic Society of Japan 131 (9) 501-505 2023年8月

    出版者・発行元:None

    DOI: 10.2109/jcersj2.23090  

    ISSN:1882-0743

    eISSN:1348-6535

  4. Synthesis of porous γ-gallium oxide films using refrigerator aging oxidation from gallium nanoparticles 査読有り

    Tatsuya Shishido, Yamato Hayashi, Manato Izuka, Toshiki Yamanaka, Hirotsugu Takizawa

    Journal of the Ceramic Society of Japan 131 (4) 83-87 2023年4月

    DOI: 10.2109/jcersj2.22140  

  5. Near-room temperature synthesis of Zn2+-doped γ-Ga2O3 nanoparticles via direct oxidation of Zn–Ga alloy by ultrasound 査読有り

    Toshiki Yamanaka, Yamato Hayashi, Hirotsugu Takizawa

    Journal of the Ceramic Society of Japan 131 (4) 100-105 2023年4月

    出版者・発行元:None

    DOI: 10.2109/jcersj2.22146  

    ISSN:1882-0743

    eISSN:1348-6535

  6. Sonochemical decomposition of noble metal oxides and sonochemical alloying of gold–silver systems

    Yamato Hayashi, Yusuke Ebato, Ryoma Onishi, Hirotsugu Takizawa

    Ultrasonics Sonochemistry 89 106115-106115 2022年9月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ultsonch.2022.106115  

    ISSN:1350-4177

  7. Sonochemical synthesis of supersaturated Ga–Al liquid-alloy fine particles and Al3+-doped γ-Ga2O3 nanoparticles by direct oxidation at near room temperature

    Toshiki Yamanaka, Yamato Hayashi, Hirotsugu Takizawa

    Ultrasonics Sonochemistry 89 106114-106114 2022年9月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ultsonch.2022.106114  

    ISSN:1350-4177

  8. Microwave-assisted titanium nitride coating processing using nitride powders in ambient atmosphere

    Nozomi Iizuka, Jun Fukushima, Yamato Hayashi, Hirotsugu Takizawa

    Journal of Alloys and Compounds 908 164606-164606 2022年7月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.jallcom.2022.164606  

    ISSN:0925-8388

  9. C-axis texture of high-rate-sputtered Nd<sub>2</sub>Fe<sub>14</sub>B thin films: independence of sheet texture of Mo underlayer

    Takayuki Tsuchida, Jun Fukushima, Shin Saito, Yamato Hayashi, Hirotsugu Takizawa

    Japanese Journal of Applied Physics 61 (6) 065506-065506 2022年6月1日

    出版者・発行元:IOP Publishing

    DOI: 10.35848/1347-4065/ac6c10  

    ISSN:0021-4922

    eISSN:1347-4065

    詳細を見る 詳細を閉じる

    Abstract In this study, we investigated the effects of the sheet texture of the Mo underlayer on the c-axis texture of the high-rate-sputtered Nd<sub>2</sub>Fe<sub>14</sub>B phase. The magnetic properties revealed that the squareness of the Nd–Fe–B magnetic layer did not depend on the sheet texture of the Mo underlayer but on the substrate temperature: large squareness was obtained when the magnetic layer was sputtered at high substrate temperature above 500 °C. In-plane X-ray diffraction measurements indicated that the intensity of diffraction from the Nd<sub>2</sub>Fe<sub>14</sub>B (410) plane did not depend on the sheet texture of the Mo underlayer but on the substrate temperature: high intensity was obtained when the magnetic layer was sputtered at above 500 °C, which was consistent with magnetic properties. These results support that the c-axis texture of the high-rate-sputtered magnetic layer was driven by the c plane with the lowest surface energy among the crystal planes in the Nd<sub>2</sub>Fe<sub>14</sub>B phase.

  10. Kinetics of CO<inf>2</inf> splitting by microwave irradiation using honeycomb-like pellets of Fe<inf>3</inf>O<inf>4</inf>/FeO

    Jun Fukushima, Masahiro Tanaka, Sadatsugu Takayama, Hirotsugu Takizawa

    Chemical Engineering Journal 428 2022年1月15日

    DOI: 10.1016/j.cej.2021.131087  

    ISSN:1385-8947

    詳細を見る 詳細を閉じる

    Thermochemical fuel production is expected to improve CO2 utilization, and two-step chemical looping processes such as those driven by solar energy are being investigated extensively. In this study, CO2 splitting was performed under microwave irradiation using iron oxides (Fe3O4 and FeO) as the reducing agents. In addition, honeycomb-like pellets of the oxides were used to increase the contact area with the CO2 gas and prevent sintering at high temperatures. The microwave radiation could heat both Fe3O4 powder and the honeycomb-like pellets of the two iron oxides rapidly. The kinetics of the reduction of CO2 to CO under microwave irradiation were investigated by in-situ gas analysis. The apparent activation energy as calculated from the Arrhenius plot was 76.1 kJ/mol for the Fe3O4 powder, 48.3 kJ/mol for the honeycomb-like FeO pellets, and 25.3 kJ/mol for the honeycomb-like Fe3O4 pellets. The proposed microwave-based process for CO2 splitting using honeycomb-like pellets is a promising one for the processing of large amounts of CO2 gas per unit time.

  11. Low-temperature hydrogen reduction of iron oxide by controlling the water potential using a CaH2 drying agent

    Takayuki Tsuchida, Jun Fukushima, Masahiro Tobise, Yamato Hayashi, Hirotsugu Takizawa

    Journal of Solid State Chemistry 302 122441-122441 2021年10月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.jssc.2021.122441  

    ISSN:0022-4596

  12. Reduction of metal oxides using thermogravimetry under microwave irradiation

    Satoshi Fujii, Masahiro Yamamoto, Naoto Haneishi, Shuntaro Tsubaki, Jun Fukushima, Hirotsugu Takizawa, Yuji Wada

    AIP Advances 11 (6) 065207-065207 2021年6月1日

    出版者・発行元:{AIP} Publishing

    DOI: 10.1063/5.0050907  

    eISSN:2158-3226

    詳細を見る 詳細を閉じる

    Chemical reactions performed under microwave irradiation often demonstrate high reaction rates, high selectivity, and low reaction temperatures, which allows for more compact reactors and more energy-efficient processes than used in conventional heating methods. In this study, we discovered a new chemical reaction and proposed a new material synthesis method, performed using a solid-state microwave source with an oscillator and a single-mode cavity. We developed a microwave heating thermogravimetry apparatus to confirm that microwave irradiation reduced the temperature of the reduction process. Next, we applied this apparatus to the reduction process of copper oxide with carbon as the reducing agent and compared microwave heating with conventional heating. We demonstrated that the reduction temperature of microwave heating was 192 °C in a magnetic (H) field and 265 °C in an electric (E) field, which were lower than those of conventional heating. For microwave heating in the E-field, plasma strongly affected the reaction process, leading to a reduction in the reaction temperature. For microwave heating in the H-field, localized heating occurred and the average reaction temperature was lower. Using the obtained results, an applicator suitable for these modes can be designed, enabling a reduction process with an additional energy-saving effect.

  13. Decrease in the crystallite diameter of solid crystalline magnetite around the curie temperature by microwave magnetic fields irradiation

    Takayuki Tsuchida, Jun Fukushima, Hirotsugu Takizawa

    Nanomaterials 11 (4) 2021年4月

    DOI: 10.3390/nano11040984  

    eISSN:2079-4991

    詳細を見る 詳細を閉じる

    A decrease in the crystallite diameter of ferrites irradiated with microwaves has been considered as a non-thermal effect of so-called de-crystallization; however, its mechanism has not been elucidated. We hypothesized that a decrease in the crystallite diameter is caused by interaction between the ordered spins of ferrite and the magnetic field of microwaves. To verify this, we focused on magnetite with a Curie temperature of 585 C. Temperature dependence around this temperature and time dependence of the crystallite diameter of the magnetite irradiated with microwaves at different temperatures and durations were investigated. From the X-ray diffraction data, the crystallite diameter of magnetite exhibited a minimum value at 500 C, just below the Curie temperature of magnetite, where the energy loss of the interaction between magnetite’s spins and the microwaves takes the maximum value. The crystallite diameter exhibited a minimum value at 5 min irradiation time, during which the microwaves were excessively absorbed. Transmission electron microscopy observations showed that the microstructure of irradiated magnetite in this study was different from that reported previously, indicating that a decrease in the crystallite diameter is not caused by de-crystallization but its similar phenomenon. A decrease in coercivity and lowering temperature of Verwey transition were observed, evidencing decreased crystallite diameter. This study can thus contribute to the development of the theory of a non-thermal effect. ◦ ◦

  14. Sonochemical effect and pore structure tuning of silica xerogel by ultrasonic irradiation of semi-solid hydrogel

    Maeda, Y., Hayashi, Y., Fukushima, J., Takizawa, H.

    Ultrasonics Sonochemistry 73 2021年

    DOI: 10.1016/j.ultsonch.2021.105476  

    ISSN:1873-2828 1350-4177

    eISSN:1873-2828

    詳細を見る 詳細を閉じる

    Silica xerogels were prepared by the sol-gel method under ultrasonic irradiation, using tetraethylorthosilicate (TEOS) as the starting material. Hexamethyldisiloxane (HMDSO) was used as the hydrophobizing agent. When preparing silica xerogel, it is necessary to perform aging and hydrophobization to suppress shrinkage during ambient pressure drying, however, such treatments are time-consuming. In this study, the semi-solid hydrogel was irradiated with ultrasonic for the first time in order to accelerate aging and hydrophobic treatment, and the effect of ultrasonic frequency on structure was investigated. Firstly, ultrasonic irradiation was performed at frequencies of 100 kHz and 500 kHz, followed by hydrophobic treatment at a frequency of 500 kHz, in order to promote aging. The results identify optimum conditions for ultrasonic irradiation to promote aging and hydrophobization reactions, and it was found to be possible to prepare silica xerogels in less than 1/5 of the conventional time. The silica xerogels had a low density and the shrinkage was suppressed. In this study, it was found that ultrasonic irradiation of semi-solid hydrogel was very effective for promoting the reaction.

  15. Room-temperature synthesis of γ-Ga<inf>2</inf>O<inf>3</inf> nanoparticles from gallium metal via ultrasound irradiation

    Takano, Y., Hayashi, Y., Fukushima, J., Takizawa, H.

    Advanced Powder Technology 32 (3) 860-865 2021年

    DOI: 10.1016/j.apt.2021.01.032  

    ISSN:1568-5527 0921-8831

    eISSN:1568-5527

    詳細を見る 詳細を閉じる

    In this study, gallium oxide (Ga O ) nanoparticles were synthesized by sonochemical techniques at room temperature. We investigate the ultrasound irradiation conditions and the solvent type to synthesize Ga O nanoparticles. γ-Ga O nanoparticles were synthesized by irradiating gallium metal with ultrasound in hydrazine monohydrate solvent. The irradiation of hydrazine with ultasound suppresses the generation of ·OH, and GaOOH was not formed, and gallium metal directly oxidized. When the synthesized γ-Ga O nanoparticles were heat-treated, a transition to β-Ga O was observed. The heat-treated Ga O nanoparticles showed excellent photocatalytic activity for the decomposition of RhB under UV irradiation. 2 3 2 3 2 3 2 3 2 3 2 3

  16. Vanadium coordination environment in phospho-vanadate glass for improving water durability

    Aoyagi, T., Takamatsu, D., Onodera, Y., Naito, T., Onodera, T., Miyake, T., Kohara, S., Ina, T., Hayashi, Y., Takizawa, H.

    Journal of the Ceramic Society of Japan 128 (5) 273-278 2020年

    出版者・発行元:Ceramic Society of Japan

    DOI: 10.2109/jcersj2.19238  

    ISSN:1348-6535 1882-0743

    eISSN:1348-6535

  17. Controlling oxygen coordination and valence of network forming cations 国際誌

    Aoyagi, T., Kohara, S., Naito, T., Onodera, Y., Kodama, M., Onodera, T., Takamatsu, D., Tahara, S., Sakata, O., Miyake, T., Suzuya, K., Ohara, K., Usuki, T., Hayashi, Y., Takizawa, H.

    Scientific Reports 10 (1) 7178-7178 2020年

    DOI: 10.1038/s41598-020-63786-y  

    ISSN:2045-2322

    詳細を見る 詳細を閉じる

    Understanding the structure-property relationship of glass material is still challenging due to a lack of periodicity in disordered materials. Here, we report the properties and atomic structure of vanadium phosphate glasses characterized by reverse Monte Carlo modelling based on neutron/synchrotron X-ray diffraction and EXAFS data, supplemented by Raman and NMR spectroscopy. In vanadium-rich glass, the water durability, thermal stability and hardness improve as the amount of P2O5 increases, and the network former of the glass changes from VOx polyhedra to the interplay between VOx polyhedra and PO4 tetrahedra. We find for the first time that the coordination number of oxygen atoms around a V4+ is four, which is an unusually small coordination number, and plays an important role for water durability, thermal stability and hardness. Furthermore, we show that the similarity between glass and crystal beyond the nearest neighbour distance is important for glass properties. These results demonstrate that controlling the oxygen coordination and valence of the network-forming cation is necessary for designing the properties of glass.

  18. Fabrication and growth of c -axis textured Nd<inf>2</inf>Fe<inf>14</inf>B thin films by high-rate sputtering

    Tsuchida, T., Fukushima, J., Hinata, S., Hayashi, Y., Saito, S., Takizawa, H.

    Journal of Applied Physics 127 (10) 2020年

    DOI: 10.1063/1.5143056  

    ISSN:1089-7550 0021-8979

    eISSN:1089-7550

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    To apply Nd-Fe-B thin films for mass-produced heat-assisted magnetic recording media, we investigated the high-rate sputtering conditions required to obtain c-axis textured Nd Fe B thin films and analyzed the growth mechanism. Magnetization curves indicated that higher substrate temperatures and sputtering rates resulted in a higher degree of perpendicular magnetic anisotropy; a Nd-Fe-B layer deposited at a substrate temperature (T ) of 600 °C and a sputtering rate (R ) of 2.6 nm/s had the easy axis perpendicular to the film plane. The dependence of the magnetic properties on the sputtering rate was due to a decrease in the substrate temperature during sputtering; there was a threshold for obtaining a high squareness ratio. X-ray diffraction analysis and transmission electron microscopy (TEM) images showed that the c-axis textured Nd Fe B crystal phase was formed in the Nd-Fe-B layer deposited at T = 600 °C and R = 2.6 nm/s, which resulted in the highly perpendicular magnetic anisotropy. In addition, the TEM images showed a layer of Nd Fe B with no obvious lattice fringes near the interface between the Nd-Fe-B layer and Mo underlayer, while the lattice fringes of the Nd Fe B phase were not parallel to this interface but gently curved along the Mo cap layer. We propose that the c-axis orientation was achieved by the rotation of the c plane, which has the lowest surface energy in the Nd Fe B phase, toward the vacuum-side surface during sputtering. 2 14 sub_0 sp 2 14 sub_0 sp 2 14 2 14 2 14

  19. Microwave Irradiation Process for Al–Sc Alloy Production 査読有り

    Fujii, S., Suzuki, E., Inazu, N., Tsubaki, S., Fukushima, J., Takizawa, H., Wada, Y.

    Scientific Reports 10 (1) 2020年

    DOI: 10.1038/s41598-020-59664-2  

    ISSN:2045-2322

    eISSN:2045-2322

    詳細を見る 詳細を閉じる

    © 2020, The Author(s). Scandium is being explored as an alloying element for aluminium alloys, which are gaining importance as high-performance lightweight structural alloys in the transportation industry. Sc-rich ScAlN thin films show strong piezoelectricity and can be fabricated on a hard substrate for use as wideband surface acoustic wave filters in next-generation wireless mobile communication systems. However, the use of ScAlN thin films in microelectromechanical system devices is limited by the high cost of metallic Sc, which is due to the difficulty in smelting of this material. Here, we propose a novel microwave irradiation process for producing Al-Sc alloys, with Mg ions as a reducing agent. Although scandium oxide is thermodynamically stable, intermetallic Al3Sc is obtained in high yield (69.8%) via a low-temperature (660 °C) reduction reaction under microwave irradiation. Optical spectroscopy results and thermodynamic considerations suggest a non-thermal equilibrium reaction with the univalent magnesium ions excited by microwave irradiation.

  20. Microwave heating behavior in SiC Fiber-MO<inf>2</inf> mixtures (M = Ce, Zr)-selective heating of micrometer-sized fibers facilitated by ZrO<inf>2</inf> Powder 査読有り

    Kashimura, K., Fukushima, J., Namioka, T., Fujii, T., Takizawa, H., Fukushima, H.

    Processes 8 (1) 2020年

    DOI: 10.3390/pr8010047  

    ISSN:2227-9717

    eISSN:2227-9717

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    © 2019 by the authors. SiC fiber-MO2 (M= Ce, Zr) mixtures with various compositions were heated by applying an 80 W microwave electric field, to investigate their heating rate, maximum temperature, and dielectric constant. For the SiC fiber-CeO2 mixture, all three parameters continued to increase as the weight ratio of the SiC fiber increased; in contrast, for the SiC fiber-ZrO2 mixture, these parameters reached a maximum value at a certain composition. A thermal gradient of 500 °C was observed at a microlevel in the SiC fiber-ZrO2 mixture, and hot spots were located in regions with a certain composition. This result not only contributes to designing a novel good microwave absorber but also presents new aspects with regard to high-temperature microwave processing, including the mechanism behind the high-temperature gradients on the order of micrometers as well as engineering applications that utilize these high-temperature gradients.

  21. Nitridation reaction of titanium powders by 2.45 ghz multimode microwave irradiation using a SiC susceptor in atmospheric conditions 査読有り

    Fukushima, J., Kashimura, K., Takizawa, H.

    Processes 8 (1) 2020年

    DOI: 10.3390/pr8010020  

    ISSN:2227-9717

    eISSN:2227-9717

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    © 2019 by the authors. A titanium nitride (TiN) coating using microwaves can be accomplished in air, and satisfies the required conditions of an on-demand TiN coating process. However, the coating mechanism using microwaves is not completely clear. In this study, to understand the detailed mechanism of microwave titanium nitridation in air, the quantity of nitrogen and oxygen in reacted TiN powder has been investigated by an inert melting method. Titanium powders were irradiated with microwaves by a multi-mode type 2.45 GHz microwave irradiation apparatus, while also being held at various temperatures for two different dwell times. X-ray diffraction (XRD) results revealed that nitridation of the powder progressed with increasing process temperature, and the nitridation corresponds to the powder color after microwave irradiation. The nitrogen contents of the samples increased with increasing processing temperature and dwell time, unlike oxygen. It is postulated that the reaction of convected air with titanium is a key role to control nitridation in this system.

  22. Formation of particle of bismuth–indium alloys and particle diameter by ultrasonic cavitation

    Furusawa, A., Hine, K., Hayashi, Y., Takizawa, H.

    Ultrasonics Sonochemistry 50 322-330 2019年

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ultsonch.2018.09.034  

    ISSN:1873-2828 1350-4177

  23. Facile synthesis and thermal properties of waterglass-based silica xerogel nanocomposites containing reduced graphene oxide

    Oikawa, K., Toyota, K., Sakatani, S., Hayashi, Y., Takizawa, H.

    Ceramics International 45 (4) 4201-4207 2019年

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ceramint.2018.11.089  

    ISSN:0272-8842

  24. High-pressure synthesis and crystal structure of a novel intermetallic compound Mn(Al,Ge)<inf>5</inf>

    Sasaki, T., Kato, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Journal of Alloys and Compounds 806 58-62 2019年

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.jallcom.2019.07.239  

    ISSN:0925-8388

  25. Enhancement of transient thermal stability and flame retardancy of hydrophobic silica xerogel composites via carbon family material doping

    Oikawa, K., Toyota, K., Okazaki, T., Okada, S., Sakatani, S., Hayashi, Y., Takizawa, H.

    Journal of Asian Ceramic Societies 7 (4) 449-459 2019年

    出版者・発行元:Informa UK Limited

    DOI: 10.1080/21870764.2019.1656358  

    ISSN:2187-0764

    eISSN:2187-0764

  26. Crystal structure and grain formation mechanism of bismuth–indium particles generated by ultrasonic irradiation

    Furusawa, A., Hine, K., Kitaura, H., Hayashi, Y., Takizawa, H.

    Journal of Materials Science 54 (16) 10998-11008 2019年

    出版者・発行元:Springer Science and Business Media LLC

    DOI: 10.1007/s10853-019-03668-5  

    ISSN:1573-4803 0022-2461

    eISSN:1573-4803

  27. Synthesis of high aspect ratio silver nanowire precursor by two-step ultrasonic irradiation and its application to transparent conductive film 査読有り

    Fujita, K., Hayashi, Y., Fukushima, J., Takizawa, H.

    Journal of the Ceramic Society of Japan 127 (10) 655-662 2019年

    DOI: 10.2109/jcersj2.19068  

    ISSN:1348-6535 1882-0743

  28. Enhancement of Fixed-bed Flow Reactions under Microwave Irradiation by Local Heating at the Vicinal Contact Points of Catalyst Particles 査読有り

    Haneishi, N., Tsubaki, S., Abe, E., Maitani, M.M., Suzuki, E.-I., Fujii, S., Fukushima, J., Takizawa, H., Wada, Y.

    Scientific Reports 9 (1) 2019年

    出版者・発行元:Springer Science and Business Media LLC

    DOI: 10.1038/s41598-018-35988-y  

    ISSN:2045-2322

    eISSN:2045-2322

  29. Survey of new materials by solid state synthesis under external fields: High-pressure synthesis and microwave processing of inorganic materials

    Takizawa, H.

    Journal of the Ceramic Society of Japan 126 (6) 2018年

    DOI: 10.2109/jcersj2.18036  

    ISSN:1348-6535 1882-0743

  30. Nanoparticle fabrication

    Inoue, M., Hayashi, Y., Takizawa, H., Suganuma, K.

    Nanopackaging: Nanotechnologies and Electronics Packaging, Second Edition 2018年

    DOI: 10.1007/978-3-319-90362-0_7  

  31. Size control of Ti <inf>4</inf> O <inf>7</inf> nanoparticles by carbothermal reduction using a multimode microwave furnace 査読有り

    Fukushima, J., Takizawa, H.

    Crystals 8 (12) 444-452 2018年

    DOI: 10.3390/cryst8120444  

    ISSN:2073-4352

  32. Kinetics of microwave synthesis of AlN by carbothermal-reduction–nitridation at low temperature 査読有り

    H. Chikami, J. Fukushima, Y. Hayashi, H. Takizawa

    Journal of the American Ceramic Society 101 (11) 4905-4910 2018年

    DOI: 10.1111/jace.15903  

    ISSN:1551-2916 0002-7820

  33. Containerless melting and synthesis of eutectic BaTiO<inf>3</inf>/CoFe<inf>2</inf>O<inf>4</inf> by microwave irradiation 査読有り

    Fukushima, J., Ara, K., Hayashi, Y., Takizawa, H.

    Materials Letters 216 42-45 2018年

    DOI: 10.1016/j.matlet.2017.12.133  

    ISSN:1873-4979 0167-577X

  34. Microwave synthesis of carbon-coated Ti<inf>4</inf>O<inf>7</inf> nanorods by rapid carbothermal reduction processing 査読有り

    Fukushima, J., Takeuchi, T., Hayashi, Y., Takizawa, H.

    Chemical Engineering and Processing - Process Intensification 125 27-33 2018年

    DOI: 10.1016/j.cep.2018.01.002  

    ISSN:0255-2701

  35. In situ spectroscopic analysis of the carbothermal reduction process of iron oxides during microwave irradiation 査読有り

    Fukushima, J., Takizawa, H.

    Metals 8 (1) 49-58 2018年

    DOI: 10.3390/met8010049  

    ISSN:2075-4701

  36. Linear magnetic field dependence of the magnetodielectric effect in eutectic BaTiO<inf>3</inf>-CoFe<inf>2</inf>O<inf>4</inf> multiferroic material fabricated by containerless processing 査読有り

    Fukushima, J., Ara, K., Nojima, T., Iguchi, S., Hayashi, Y., Takizawa, H.

    Applied Physics Letters 112 (21) 12903-1-212903-5 2018年

    DOI: 10.1063/1.5025072  

    ISSN:0003-6951

  37. Effect of aspect ratio on the permittivity of graphite fiber in microwave heating 国際誌 査読有り

    Fukushima, J., Tsubaki, S., Matsuzawa, T., Kashimura, K., Mitani, T., Namioka, T., Fujii, S., Shinohara, N., Takizawa, H., Wada, Y.

    Materials 11 (1) 169 2018年

    DOI: 10.3390/ma11010169  

    ISSN:1996-1944

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    Microwave (MW) heating has received attention as a new heating source for various industrial processes. Some materials are expected to be a more effective absorber of MW, and graphite is observed as a possible candidate for high-temperature application. We investigated the dependence of the aspect ratio of graphite fibers on both their heating behavior and permittivity under a 2.45 GHz MW electric field. In these experiments, both loss tangent and MW heating behavior indicated that the MW absorption of conductive fibers increases with their aspect ratio. The MW absorption was found to be well accounted for by the application of a spheroidal model for a single fiber. The absorption of graphite fibers decreases with increasing aspect ratio when the long axis of the ellipsoid is perpendicular to the electric field, whereas it increases with the aspect ratio when the long axis is parallel to the electric field. The analytical model indicated that MW heating of the conductive fibers is expected to depend on both the shape and arrangement of the fibers in the electric field.

  38. Synthesis and photoluminescence properties of a novel Sr<inf>2</inf>Al<inf>6</inf>O<inf>11</inf>:Mn<sup>4+</sup> red phosphor prepared with a B<inf>2</inf>O<inf>3</inf> flux 査読有り

    Sasaki, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Journal of Luminescence 194 446-451 2018年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/j.jlumin.2017.10.076  

    ISSN:0022-2313

    eISSN:1872-7883

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    A novel Mn4+-doped aluminate red phosphor Sr2Al6O11: Mn4+ was synthesized by a solid-state reaction, and we investigated its photoluminescence properties. Sr2Al6O11, which has a similar structure to Sr4Al14O25, was formed as the main phase after heating alpha-alumina, strontium carbonate, manganese dioxide, and magnesium oxide with 2.5% (B2O3) at 1000 degrees C for 12 h or more. The Sr2Al6O11: Mn4+ phosphor exhibited red photoluminescence with peaks at around 652 and 665 nm, which arise from the spin-forbidden transition of the Mn4+ cation from the E-2 to the (4)A(2) state. The phosphor can be excited by near ultraviolet or blue LED light because it had a broad excitation band from the near-ultraviolet to the blue light region. The emission intensity was increased by co-doping with Mg2+ cations, which act as charge compensators. The amount of Mg required for the most effective charge compensation was 10 times the optimum Mn concentration. From these results, we confirmed that Sr2Al6O11 could act as the host structure for Mn4+-doped phosphors.

  39. Microwave irradiation effects on the spinodal decomposition of TiO<SUB>2</SUB>-VO<SUB>2</SUB> system 査読有り

    S. Aoyagi, J. Fukushima, Y. Hayashi, H. Takizawa, 青柳 宗一郎, 福島 潤, 林 大和, 滝澤 博胤

    JEMEA Bulletin 1 9-16 2017年12月22日

  40. Synthesis of Ti<inf>4</inf>O<inf>7</inf> nanoparticles by carbothermal reduction using microwave rapid heating 査読有り

    Takeuchi, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Catalysts 7 (2) 65-1-65-8 2017年

    出版者・発行元:MDPI AG

    DOI: 10.3390/catal7020065  

    ISSN:2073-4344

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    The polymer electrolyte fuel cell (PEFC) is an attractive power generation method from the perspective of environmental protection. Carbon is usually used as a catalyst support in PEFC, but it is oxidized under high electrical potential conditions. Ti4O7 is expected as a new catalyst support because of its high electrical conductivity and chemical resistivity. Though Ti4O7 as a catalyst support must have a high specific surface area for a high performance, it is difficult to synthesize nanostructured Ti4O7. In this research, Ti4O7 nanoparticles with a size of about 60 nm were synthesized by carbothermal reduction of TiO2 nanoparticles with polyvinylpyrrolidone (carbon source) using 2.45 GHz microwave irradiation. The experiment condition was at 950 degrees C for 30 min and the samples synthesized by conventional heating showed a grain growth. The findings of this study suggest that microwave processing can drastically reduce the total processing time for the synthesis of nanostructured Ti4O7.

  41. In situ analysis of reaction kinetics of reduction promotion of NiMn<inf>2</inf>O<inf>4</inf> under microwave H-field irradiation 査読有り

    Fukushima, J., Takayama, S., Goto, H., Sato, M., Takizawa, H.

    Physical Chemistry Chemical Physics 19 (27) 17904-17908 2017年

    出版者・発行元:ROYAL SOC CHEMISTRY

    DOI: 10.1039/c7cp02728a  

    ISSN:1463-9076

    eISSN:1463-9084

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    Reaction kinetics during microwave H-field heating and electric furnace heating were investigated to verify the effect of rapid heating and the non-thermal microwave effect. This work is focused on the ferromagnetic material NiMn2O4, and the reduction reaction under rapid heating is investigated using an in situ analysis device. The results showed that the activation energy varied with the heating rate under microwave H-field irradiation, and it was the same as that in an electric furnace when the heating rate was the same. On the other hand, under microwave H-field irradiation, the reduction reaction began from a significantly low temperature compared with that of electric furnace heating. The results suggest that the transition theory during microwave irradiation should be expanded to include the effect of spin waves excited by a microwave H-field on magnetic materials.

  42. Effects of Al- and Sn-substitution on photoluminescence properties of Mn<sup>4+</sup>-doped spinel-type Mg<inf>2</inf>TiO<inf>4</inf> phosphor 査読有り

    Sasaki, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Journal of Luminescence 187 540-545 2017年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/j.jlumin.2017.03.026  

    ISSN:0022-2313

    eISSN:1872-7883

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    Solid solution phosphors in which the octahedral sites Mg2TiO4:Mn4+ were substituted by Al3+ and Sn4+ were synthesized and the relationship between the coordination environment of Mn4+ and the emission wavelength was investigated. Mn4+-doped Mg2TiO4-MgAl2O4 and Mg2TiO4-Mg2SnO4 red phosphors were prepared by a solid-state reaction. Mg2-xTi1-xAl2xO4:Mn4+ and Mg(2)Ti(1-y)SnyO(4):Mn4+ were synthesized at 1400 degrees C and 1200 degrees C, respectively. The crystal structure parameters were refined using the RIETAN-FP program and the average bond lengths were calculated from the refined crystal structures of Mg2-xTi1-xAl2xO4:Mn4+ and Mg(2)Ti(1-y)SnyO(4):Mn4+. The emission peak of the Al-substituted sample shifted toward shorter wavelengths with increasing Al concentration, whereas the emission peak of the Sn-substituted sample shifted toward longer wavelengths with increasing Sn concentration. In the E-2 -&gt;(4)A(2) transition, the emission peak wavelength of the Mn4'-activated spinet-type solid solution increased almost linearly with increasing average bond length between cation and anion in octahedral sites, L-oct. These results indicate that there is a strong positive correlation between Loa and the emission peak wavelength for the solid solution compositions studied in this work. (C) 2017 Elsevier B.V. All rights reserved.

  43. Synthesis and photoluminescence properties of Mn<sup>4+</sup>-doped magnetoplumbite-related aluminate X-type Ca<inf>2</inf>Mg<inf>2</inf>Al<inf>28</inf>O<inf>46</inf> and W-type CaMg<inf>2</inf>Al<inf>16</inf>O<inf>27</inf> red phosphors 査読有り

    Sasaki, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Ceramics International 43 (9) 7147-7152 2017年

    出版者・発行元:ELSEVIER SCI LTD

    DOI: 10.1016/j.ceramint.2017.02.149  

    ISSN:0272-8842

    eISSN:1873-3956

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    Novel Mn4+-doped magnetoplumbite-related aluminate X-type Ca2Mg2Al28O46 and W-type CaMg2Al16O27 red phosphors were synthesized by solid-state reaction, and we investigated their photoluminescence properties. X-type Ca2Mg2Al28O46:Mn4+ and W-type CaMg2Al16O27:Mn4+ exhibited red photoluminescence, with peaks at 655 and 656 nm, arising from the spin-forbidden E-2 -&gt;(4)A(2) transition of Mn4+ under near-ultraviolet and blue light excitation, respectively. Therefore, these red phosphors can be excited by near ultraviolet or blue LED light. The photoluminescence properties of these phosphors were similar because magnetoplumbite-related structures crystallize similarly, forming structures consisting of stacked S and R blocks. From these results, we confirmed that magnetoplumbite-related compounds can act as the host structure for Mn(4+-)doped phosphors.

  44. Synthesis and photoluminescence properties of a novel aluminosilicate Sr<inf>3</inf>Al<inf>10</inf>SiO<inf>20</inf>:Mn<sup>4+</sup> red phosphor 査読有り

    Sasaki, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Journal of Luminescence 188 101-106 2017年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/j.jlumin.2017.04.014  

    ISSN:0022-2313

    eISSN:1872-7883

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    A novel aluminosilicate red phosphor Sr3Al10SiO20:Mn4+, which has some octahedral sites, was synthesized by a solid-state reaction, and we investigated its photoluminescence properties. Sr3Al10SiO20 doped with tetravalent manganese showed a red photoluminescence transition from E-2 to (4)A(2) after excitation in the near ultraviolet region to the blue region in the visible spectrum. The Sr3Al10SiO20:Mn4+ synthesized at 1500 degrees C for 6 h exhibited maximum emission intensity. From these results, it was confirmed that aluminosilicates could be the host structure for Mn4+ -doped phosphors.

  45. Synthesis of lead-free solder particles using high-speed centrifugal atomization 査読有り

    Furusawa, A., Akiyama, S., Sakai, K., Hayashi, Y., Takizawa, H.

    Materials Transactions 58 (10) 1458-1462 2017年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.M2017129  

    ISSN:1345-9678

    eISSN:1347-5320

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    We investigated the relationships between the centrifugal force and the disc size and rotation speed during the production of fine particles. In this study, an empirical formula was developed with the goal of obtaining an average particle size of D50. Moreover, particle production was performed at a disc rotation speed of at least 100,000 rpm, which was greater than that reported in previous studies. Our results showed that with Sn-13 mass% Sb (called Sn-13Sb), the average particle size produced at a disc rotation speed of 115,000 rpm was 12.8 mu m, with 96.5% of the particles smaller than 25 mu m.

  46. Scintillation properties of high-pressure-synthesized ZnO ceramics 査読有り

    Watanabe, K., Koshimizu, M., Fujimoto, Y., Hayashi, Y., Takizawa, H., Yanagida, T., Asai, K.

    Radiation Measurements 106 146-150 2017年

    出版者・発行元:Elsevier Ltd

    DOI: 10.1016/j.radmeas.2016.12.007  

    ISSN:1350-4487

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    We synthesized ZnO ceramics scintillators without or with dopants using a high-pressure synthesis method. The dense ceramics were successfully obtained, and the densified structure was confirmed by SEM observation. Doping with Ga is proven to be effective for suppressing the deep level (DL) emission as well as the long decay component in the scintillation temporal profile. Based on the pulse height spectra, the light yield is estimated to be 1500 photons/5.5-MeV alpha-ray for the undoped ceramics, and the doped ceramics exhibit similar light yields. These results indicate that the high-pressure synthesis method is effective for the synthesis of dense ZnO ceramics scintillators with a fast response.

  47. Effect of organic hydrophobic groups on the pore structure and thermal properties of waterglass-based silica xerogels 査読有り

    Oikawa, K., Toyota, K., Sakatani, S., Hayashi, Y., Takizawa, H.

    Journal of the Ceramic Society of Japan 125 (12) 906-912 2017年

    出版者・発行元:Ceramic Society of Japan

    DOI: 10.2109/jcersj2.17131  

    ISSN:1348-6535 1882-0743

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    Hydrophobic silica xerogels containing trimethylsilyl (TMS) and dimethylsilyl (DMS) organic hydrophobic functional groups were synthesized using waterglass as the starting material. Five types of hydrophobic silica xerogels with varying surface coverages of the TMS and DMS groups were synthesized by changing the molecular structure of siloxane, which was used to introduce the hydrophobic moieties into the hydrogel and to investigate the resultant surface structures and thermal characteristics. The results revealed that the relative area of silica xerogels was smaller with a higher coverage of DMS groups. In addition, the thermal decomposition temperature of the silyl group shifted to higher temperatures, and the weight reduction during heating was also relatively limited in the above samples.

  48. P17 超音波反応場を用いた銀ナノワイヤー前駆体の合成と透明導電膜への応用

    藤田 恭輔, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 25 65-66 2016年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.25.0_65  

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    Silver Nanowires, Silver Carboxylates, Transparent Conductive Films, Low-Dimension MaterialsAbstract: Silver nanowires transparent conductive films are expected as a material to replace indium tin oxidefilms. Silver nanowires are mainly synthesized by the polyol method, which used protective agents to achievean anisotropic crystal growth. However, protective agents decrease conductivity of the films because theycover the surface of nanowires. In this study, we have conveniently synthesized needle-shaped silvercarboxylates by ultrasound irradiation, and then obtained silver nanowires transparent conductive films byspray coating them on substrates and exposing them to gas-phase hydrazine.<br>Silver carboxylates were synthesized by ultrasound irradiation to mixture that contains silver(I) oxide, aceticacid, propionic acid, and ethanol. These carboxylates were put onto a glass substrate, and then reduced byexposure to hydrazine gas (vaporized hydrazine monohydrate). The obtained samples were characterized byFE-SEM, XRD, TG-DTA, four-probe method, and UV-Vis.<br>Silver oxide completely reacted and silver carboxylates were produced after 1 h of ultrasound irradiation(22.32-44.13 kHz, 100 W). Raw materials were most homogeneity dispersed and consumed at 44.13 kHz. Thestudy on coating conditions of the precursor, in case of short height of the spray, produced transparentconductive films showed low transmittance and very low resistance. And high transmittance and lowresistance were achieved by adjusting the coating time and spray height.

  49. Synthesis and Optimization of Silver Nanowire Transparent Conductive Film by Organic Needle-shaped Precursor Painting Reduction Method 査読有り

    Yamato Hayashi, Kyosuke Fujita, Ichihito Narira, Masahiro Inoue, Hirotsugu Takizawa

    2016 IEEE 16TH INTERNATIONAL CONFERENCE ON NANOTECHNOLOGY (IEEE-NANO) 257-260 2016年

    出版者・発行元:IEEE

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    A process of silver nanowire transparent conductive films has been developed to synthesize by organic needle-shaped precursor painting reduction. Needle-shaped nanowire precursors are simply synthesized by ultrasound irradiation of silver oxide and carboxylic acid as starting materials. The aspect ratio of the needle-shaped precursors is chenged by condition of ultrasound irradiation. Silver nanowires can be easily obtained by reducing these needle-shaped precursors with hydrazine gas. The morphology of the resulting nanowires is different from that of typical nanowires that have been reported. The small nanoparticles are connected to form polycrystal nanowire. The polycrystal silver nanowire is considered to increase the transparency of the film because of its rough morphology. This method can synthesize silver nanowires and fabricate the transparent conductive film simultaneously, in low cost and high throughput.

  50. Control of magnetic properties of NiMn<inf>2</inf>O<inf>4</inf> by a microwave magnetic field under air 査読有り

    Goto, H., Fukushima, J., Takizawa, H.

    Materials 9 (3) 169-1-169-9 2016年

    出版者・発行元:MDPI AG

    DOI: 10.3390/ma9030169  

    ISSN:1996-1944

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    NiMn prepared by conventional heating was irradiated with a microwave H-field using a single-mode cavity under air and magnetic properties of the microwave-irradiated material were investigated. X-ray diffraction and transmission electron microscopy demonstrated that the phase and microstructure are not affected by H-field irradiation. Measurements of the magnetization as a function of temperature revealed that the antiferromagnetic sublattice disappeared and electron spin resonance showed the existence of Mn 2+, suggesting that Mn3+ is partially reduced. Moreover, the magnetization of NiMn was controlled from 35.3 to 18.2 emu/g and the coercivity from 140 to 750 Oe by changing the sample temperature during microwave irradiation. The reduction reaction of NiMn is controlled by microwave H-field irradiation, resulting in control over the magnetic properties.

  51. Enhanced reduction of copper oxides via internal heating, selective heating, and cleavage of Cu-O bond by microwave magnetic-field irradiation 査読有り

    Fukushima, J., Takizawa, H.

    Materials Chemistry and Physics 172 47-53 2016年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/j.matchemphys.2015.12.057  

    ISSN:0254-0584

    eISSN:1879-3312

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    The reduction behavior of copper (II) oxide (CuO) covered with boron nitride (BN) powder under microwave H-field irradiation was investigated to understand the mechanism of enhanced reduction of CuO in microwave processing. Internal heating using microwave irradiation resulted in a unidirectional diffusion of oxygen from inside the CuO pellet to its outside, and selective heating prevented the oxidization of the BN powder near the CuO pellet. A quantum chemical interpretation of this phenomenon revealed that the microwave H-field couples to the Fermi level electrons of CuO, and the copper-oxygen bond may be cleaved by both microwave energy and thermal energy. As a result, microwave H-field irradiation resulted in a more effective reduction of CuO to copper metal compared to conventional heating. (C) 2015 Elsevier B.V. All rights reserved.

  52. Synthesis and photoluminescence properties of SrLaAlO<inf>4</inf>: Ti green-emitting phosphor 査読有り

    Watanabe, N., Hayashi, Y., Fukushima, J., Takizawa, H.

    Materials Science Forum 868 1-5 2016年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.868.1  

    ISSN:1662-9752 0255-5476

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    Ti-doped SrLaAlO4 green-emitting phosphor was synthesized via solid-state reactions in air and N2 atmosphere. Sample heated in air showed no emission, however, sample heated in N2 showed broad green emission around 492 nm and broad near-infrared emission around 950 nm by 321 nm near-ultraviolet excitation. XPS measurement and UV-Vis diffuse reflectance spectra suggest that Ti in the sample was reduced to Ti3+ state when the sample was heated in N2. Possible emission mechanism of the sample can be explained as O2-–Ti3+ charge-transfer transition.

  53. Photoluminescence properties of the magnetoplumbite-type BaMg<inf>6</inf>Ti<inf>6</inf>O<inf>19</inf>:Mn<sup>4+</sup> and spinel-type Mg<inf>2</inf>TiO<inf>4</inf>:Mn<sup>4+</sup> 査読有り

    Sasaki, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Materials Science Forum 868 73-78 2016年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.868.73  

    ISSN:1662-9752 0255-5476

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    Mn4+-doped magnetoplumbite-type BaMg6Ti6O19 and spinel-type Mg2TiO4 red phosphors were synthesized by a solid-state reaction. BaMg6Ti6O19:Mn4+ and Mg2TiO4:Mn4+ were formed as main and single phase above 1200 ºC, respectively. Although the emission peak of BaMg6Ti6O19:Mn4+ and Mg2TiO4:Mn4+ were almost the same, the excitation peak of BaMg6Ti6O19:Mn4+ and Mg2TiO4:Mn4+ were different. The4A2→4T1 spin-allowed transition peak of Mg2TiO4:Mn4+ shifted to a shorter wavelength side than that of BaMg6Ti6O19:Mn4+ and 4A2→4T2 transition shifted to a longer wavelength side. The crystal field splitting energy of Mg2TiO4:Mn4+ was lower than that of BaMg6Ti6O19:Mn4+. By the additional of R block, the racah parameter B increased and C decreased. Although the increase of B causes a blue-shift of the emission wavelength and the decrease of C causes a red-shift of the emission wavelength, PL emission wavelength was little different due to the influence of both racah parameter. Thus, it was suggested that the existence of R block results in a difference of photoluminescence properties.

  54. Low-Temperature Synthesis of Aluminum Nitride from Transition Alumina by Microwave Processing 査読有り

    Chikami, H., Fukushima, J., Hayashi, Y., Takizawa, H.

    Journal of the American Ceramic Society 99 (11) 3540-3545 2016年

    出版者・発行元:WILEY-BLACKWELL

    DOI: 10.1111/jace.14367  

    ISSN:1551-2916 0002-7820

    eISSN:1551-2916

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    Aluminum nitride (AlN) was synthesized by carbothermal reduction and nitridation method from a mixture of various transition alumina powders and carbon black using 2.45 GHz microwave irradiation in N-2 atmosphere. We achieved the synthesis of AlN at 1300-1400 degrees C using 2.45 GHz microwave irradiation for 60 min. Our results suggest that -Al2O3 is more easily nitrided than -, -, and -Al2O3. On the other hand, nitridation ratio of samples synthesized in a conventional furnace under nitrogen atmosphere were zero or very low. These results show that 2.45 GHz microwave irradiation enhanced the reduction and nitridation reaction of alumina.

  55. Oriented texture formation of crystallized Nd<inf>2</inf>Fe<inf>14</inf>B through a microwave heating process 査読有り

    Iwabuchi, Y., Fukushima, J., Sakuma, N., Ito, M., Shimo, Y., Kishimoto, H., Takizawa, H.

    Journal of Alloys and Compounds 685 566-570 2016年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/j.jallcom.2016.05.187  

    ISSN:0925-8388

    eISSN:1873-4669

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    The microstructure and magnetic properties of Nd2Fe14B crystallized by microwave heating were investigated to reveal the effect of microwave on the microstructure. The c-axis oriented and nano-sized columnar grains of Nd2Fe14B were obtained through microwave processing. The oriented texture was limited to the surface region. This microstructure could not be observed through conventional heating. It was considered that the temperature gradient caused by microwave heating was responsible for the formation of columnar grains. In addition to the change in the microstructure resulting from the heating methods, the coercivity and remanence of the microwave irradiated sample was larger than those obtained via conventional heating. (C) 2016 Elsevier B.V. All rights reserved.

  56. Electrochemical Properties and In-situ XAFS Observation of Li<inf>2</inf>O-V<inf>2</inf>O<inf>5</inf>-P<inf>2</inf>O<inf>5</inf>-Fe<inf>2</inf>O<inf>3</inf> Quaternary-glass and Crystallized-glass Cathodes 査読有り

    Aoyagi, T., Fujieda, T., Toyama, T., Kono, K., Takamatsu, D., Hirano, T., Naito, T., Hayashi, Y., Takizawa, H.

    Journal of Non-Crystalline Solids 453 28-35 2016年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/j.jnoncrysol.2016.09.016  

    ISSN:0022-3093

    eISSN:1873-4812

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    Electrochemical properties of Li2O-V2O5-P2O5-Fe2O3 quaternary-glass and crystallized-glass cathodes were compared in terms of the local structural changes of vanadium and iron ions with increasing discharge capacity by in situ X-ray absorption fine structure (XAFS) measurements. 10..Li2O-69.2V(2)O(5)-10.2P(2)O(5)-10.3Fe(2)O(3) glass was prepared by the melt-quenching method. The crystallized glass was produced by heat treatment of the glass at 375 degrees C in air. The crystal phase of the crystallized glass was found to be a single phase of beta-vanadium bronze. The glass exhibited a discharge capacity of around 300 mAh g(-1) and a capacity retention of 66% after 100 cycles. On the other hand, the crystallized glass exhibited a capacity of around 340 mAh g(-1) and a capacity retention of 68% after 100 cycles. In the cases of glass and crystallized glass, in-situ X-ray absorption near-edge spectroscopy (XANES) spectra revealed that a redox reaction of vanadium and iron ions occurs as a compensation reaction for lithium-ion insertion. In addition, the absorption-energy shift of the vanadium and iron K-edges in the case of glass was larger than that in the case of crystallized glass despite the same discharge capacity. The analysis of pre-edge peak intensities and extended X-ray absorption fine structure (EXAFS) analysis revealed that the vanadium and iron coordination symmetry of the glass can transform more easily than that of the crystallized glass under lithium-ion insertion. These results imply that the origin of good cycleability differs in the cases of glass and crystal-phase cathodes. (C) 2016 Published by Elsevier B.V.

  57. P03 超音波による銀ナノ粒子の酸化処理銅ナノ粒子表面への担持(ポスターセッション)

    佐々木 遼, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 24 25-26 2015年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.24.0_25  

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    Copper nanoparticles(CuNPs) are expected to be novel wiring materials because of low sintering temperature and low-priced ingredients. CuNPs are usable as a ink for wiring. This ink printed on a circuit board conducts electricity after proper heat treatment. However, CuNPs oxidize easily in the air. To prevent oxidation of CuNPs, additional costly process are needed such as atmosphere exchanging into an inert atmosphere. On the other hand, organic compounds have been used as protectors for CuNPs, but these non-metallic coverings often reduce conductivity of CuNPs. Hence, Cu-Ag nanocomposites(Cu-Ag NC) have been considered as an alternative method to prevent oxidation. In this study, Cu-Ag NC were easily synthesized under high concentration condition by using ultrasonic irradiation. Ultrasonic irradiation was easily process to combine metal nanoparticles with other materials. However, CuNPs and silver nanoparticles repel each other in a solvent because of positively charged particles. To change charge of CuNPs, oxidization of CuNPs is available. CuNPs were purposely oxidized, then synthesis of Cu-Ag NC became easily. Cu-Ag NC were reduced on a glass substlate, and electric resistivity of the sample were decreased from 2.267 Ωcm to 1.690 × 10^<-4> Ωcm.

  58. P12 Cr(CO)_6の超音波分解によるCrナノ粒子の合成(ポスターセッション)

    小出 真路, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 24 43-44 2015年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.24.0_43  

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    Hard chromium plating has been used to improve hardness, resistance to corrosion, friction and heat in various fields. However, alternative technology of hard chromium plating is desired because of toxicity of raw materials. Thus, we developed a novel method to fabricate a hard film by using Cr nanoparticles. Although this method is easy and environmentally friendly, Cr nanoparticles are expensive at present because Cr nanoparticles are synthesized by vapor deposition. In this study, we tried to synthesize Cr nanoparticles in solvent by ultrasonic decomposition of Cr(CO)_6. Cr(CO)_6 was fully decomposed by ultrasonic irradiation in decanol at 50 ℃ for 30 min. The product had a low crystallinity and particles sizes were about 5 nm. In TG-DTA, products exhibited weight loss (33 %) around 1000 ℃ in Ar by decomposition of organics. In XRD, Cr and Cr_2O_3 were observed after heating at 1000 ℃ in Ar. It is considered that surfaces of Cr nanoparticles were formed oxide shells of Cr_2O_3 as passive layers. When the atmosphere was changed from Ar to air in 1000 ℃, products exhibited weight gain due to oxidation of Cr.

  59. 未来社会への道筋を描くには

    滝澤 博胤

    工学教育 63 (3) 3_2-3_2 2015年

    出版者・発行元:Japanese Society for Engineering Education

    DOI: 10.4307/jsee.63.3_2  

    ISSN:1341-2167

  60. Protective agent free eco-synthesis of silver nanowire via needle-shaped silver acetate precursor 査読有り

    Sugawara, K., Hayashi, Y., Fukushima, J., Takizawa, H.

    Materials Science Forum 804 115-118 2015年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.804.115  

    ISSN:1662-9752 0255-5476

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    We developed new synthetic method of silver nanowire by reducing silver acetate precursor. Silver acetate could be easily synthesized by ultrasound irradiation to the mixture of non-toxic starting materials, only ethanol and silver(I) oxide. All of reaction was performed in relatively low temperature and it does not need any protective agents. The precursors had high aspect ratio needle-shaped morphology. They decomposed easily by heating up to 300 °C and then produce only silver without any residues. This process is expected to be new synthetic method of silver nanowire that doesn’t require any protective agents and emit much waste.

  61. Synthesis and characterization of Ag/Graphene nanocomposites by solid-liquid sonochemical reactions 査読有り

    Mochizuki, T., Hayashi, Y., Fukushima, J., Takizawa, H.

    Materials Science Forum 804 119-122 2015年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.804.119  

    ISSN:1662-9752 0255-5476

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    In this study, Graphite Oxide (GO) and Ag/Graphene nanocomposites were synthesized by solid-liquid sonochemical reactions easily and briefly. GO was synthesized by means of Hummers method using sonication or stirring. From XRD patterns and FT-IR spectra, chemical and physical effects of ultrasound promoted the oxidation of Graphite. Ag/graphene nanocomposites were synthesized from GO and silver oxide by sonication. UV-vis spectra showed the peaks of Graphene oxide and Ag nanoparticle plasmon resonance absorption. EDX images and electron diffraction patterns confirmed Ag nanoparticles were decorated on Graphene sheets by ultrasound. Using sonication, GO and Ag/Graphene nanocomposites could be synthesized easily in short time.

  62. Synthesis of copper spinels by microwave irradiation 査読有り

    Fukushima, J., Takizawa, H., Hayashi, Y.

    Ceramic Transactions 252 33-41 2015年

    出版者・発行元:Ceramic Transactions

    DOI: 10.1002/9781119183860.ch4  

    ISSN:1042-1122

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    CuFe2O4 was synthesized by microwave irradiation and conventional processing. In addition, microwave H-field annealing was conducted in order to investigate the effect of a magnetic field on tetragonal CuFe2O4. The sample synthesized with microwave E-field irradiation was cubic CuFe2O4, had a small saturation magnetization, and the same coercivity as that produced by conventional heating. In contrast, the sample synthesized with H-field irradiation had a larger saturation magnetization and a smaller coercivity than the sample synthesized by conventional heating. After H-field annealing, the sample had a large amount of cubic CuFe2O4 phase that consists of small crystallites. Moreover, the saturation magnetization increased and the coercivity decreased. These results suggest that microwaves lead to a reduction in the Jahn-Teller distortion and the magnetic property changes accordingly. It is concluded that microwaves affect the Jahn-Teller distortion of CuFe2O4 and the effect leads to changes in the phase and magnetic properties.

  63. Facile synthesis of silver-nanobeadwire transparent conductive film by organic-precursor paint reduction 査読有り

    Sugawara, K., Hayashi, Y., Fukushima, J., Takizawa, H.

    Crystal Research and Technology 50 (4) 319-330 2015年

    出版者・発行元:WILEY-V C H VERLAG GMBH

    DOI: 10.1002/crat.201400473  

    ISSN:1521-4079 0232-1300

    eISSN:1521-4079

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    A new facile process has been developed to synthesize silver nanowire transparent conductive films by reducing high-aspect-ratio, needle-shaped silver carboxylates, prepared as the precursor, while retaining their morphology. Nanowire precursors are simply obtained by ultrasound irradiation when silver (I) oxide and carboxylic acids are used as starting materials. The aspect ratio of the precursors is increased when the ultrasound irradiation is followed by microwave irradiation. Silver nanowires can be easily obtained by reducing these precursors with hydrazine gas or irradiating them with Ar plasma for a short time. The morphology of the resulting nanowires is different from that of typical nanowires that have been reported. The nanowires have porous morphology, where small nanoparticles are connected to form nanobeadwire. The nanobeadwire is considered to increase the transparency of the film because of its rough morphology. This new method can synthesize silver nanobeadwires and fabricate the transparent conductive film simultaneously, in one-step, so that it can significantly simplify manufacturing processes.

  64. Synthesis of homologous compounds Fe<inf>2</inf>O<inf>3</inf>(ZnO)<inf>m</inf> (m=6, 8, 34) by various selective microwave heating conditions 査読有り

    Nagao, D., Fukushima, J., Hayashi, Y., Takizawa, H.

    Ceramics International 41 (10) 14021-14028 2015年

    出版者・発行元:ELSEVIER SCI LTD

    DOI: 10.1016/j.ceramint.2015.07.015  

    ISSN:0272-8842

    eISSN:1873-3956

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    Homologous compounds, Fe2O3(ZnO)(m) with a modulated natural superlattice structure, were synthesized within 10 min at 1200 degrees C in a simple solid-state reaction under 2.45 and 28 GHz microwave irradiation. Transmission electron microscopy and energy dispersive X-ray spectroscopy results revealed that m decreased with increasing the synthesis temperature and microwave frequency. In the Zn-Fe-O system, gamma-Fe2O3 was heated in H and E-field and ZnO was heated in E-field under 2.45 GHz microwave irradiation. However, alpha, gamma-Fe2O3 and calcined ZnO were heated under 28 GHz microwave irradiation. This selective microwave heating resulted in the different diffusion conditions than conventional heating; therefore, homologous compounds with low m values were rapidly synthesized at low temperature. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

  65. P13 超音波反応場を用いた低沸点溶媒中でのグラファイトの直接剥離(ポスターセッション)

    望月 智文, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 23 55-56 2014年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.23.0_55  

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    Recently, graphene has attracted tremendous research interests due to its unique mechanical, electrical and thermal properties caused by a two-dimensional, single-atom-thick structure of sp2-bonded carbon atoms. In the past few years, several methods, such as chemical vapor deposition and exfoliation of graphite powder in high boiling point solvents, have been used to prepare graphene sheets. It is known that chemical reactions, stirring, dispersion and exfoliation are promoted by ultrasound-cavitation. In this study, the production of unfunctionalized and nonoxidized graphene by exfoliation of graphite flakes in solvents is synthesized and characterized. We used 2-propanol (IPA) and acetic acid as low boiling point solvents. A stable homogeneous dispersion of graphene was obtained by solid-liquid sonochemical reactions using IPA and acetic acid mixed solvents. STEM images and electron diffraction pattern shows the presence of mono- and few-layer graphenes. As a result, graphene could be synthesized in low boiling point solvent. The solvent, IPA, was simply and quickly removed by air-drying, and dose not leave any residue of the solvent in the graphene sheets.

  66. P14 超音波による銀ナノワイヤー前駆体の作製と透明導電膜への応用(ポスターセッション)

    菅原 賢太, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 23 57-58 2014年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.23.0_57  

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    Silver nanowire transparent conducting films (TCFs) are expected to be alternative materials for indium tin oxide TCFs. Silver nanowires are typically synthesized by polyol method. It requires protective agents to achieve an anisotropic crystal growth, however, protective agents cover the top surface of nanowires, and hence decrease conductivity of films. In this study, we have conveniently synthesized needle-shaped silver carboxylates by ultrasound irradiation, and then obtained silver nanowires transparent conductive films by spraying them on substrate and exposing them to gas-phase hydrazine. Silver carboxylates were synthesized by ultrasound irradiation to mixture that contains silver(I) oxide, acetic acid, propionic acid, and ethanol. These carboxylates were put onto glass or polycarbonate (PC) substrate, and then exposed to hydrazine gas (vaporized hydrazine monohydrate) to reduce. The obtained samples were characterized by FE-SEM, XRD, TG-DTA, four-point probe and UV-Vis. Silver oxide was completely reacted and silver carboxylates were produced after 1 h of ultrasound irradiation at 10-40 ℃, that is relatively low temperature compared to conventional method. Decreasing reaction temperature, it was confirmed that diameters of the precursor were reduced by 25%. Diameter and aspect ratio of the precursor were decreased for longer reaction time because of sonofragmentation. To reduce diameter with keeping aspect ratio, lower temperature can be effective. Transparent conductive films, which were produced by spraying and reducing precursor, show high transmittance and low resistance at 80 ℃ of reduction temperature. However resistivity have been drastically increased for higher temperature because their specific one-dimensional shapes have been completely lost.

  67. P27 超音波を利用した耐酸化性Cu-Agナノコンポジットの合成(ポスターセッション)

    佐々木 遼, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 23 83-84 2014年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.23.0_83  

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    Printed electronics is one of the inexpensive fabrication for electronic circuits and it is expected to be an alternative to conventional method such as photolithography. Commercial conductive ink for printed electronics often uses Ag nanoparticles(AgNPs), but AgNPs are expensive. Accordingly, Cu nanoparticles(CuNPs) are expected to replace for AgNPs, because Copper is much cheaper than silver and has high conductivity. However, Copper oxidises easily in the atmosphere. To prevent oxidation of Cu, organic compounds have been used as coverings for CuNPs, but these non-metallic coverings often reduce conductivity of CuNPs. Hence, Cu-Ag nanocomposites(Cu-Ag NC) have been considered as an alternative method to prevent Cu oxidation. In this study, Cu-Ag NC were easily synthesized under high concentration condition with microwaves and ultrasonication. Microwave heating is effective method for synthesis of nanoparticles because of its effect to heat polar solvents quickly and uniformly. Ultrasonication is easily process to synthesize composites of nanoparticles and other materials. The sample synthesized showed the form that AgNPs attached to the surface of CuNPs in its SEM images. Thermogravimetry measurement suggested that the sample has high oxidation resistance against CuNPs.

  68. Synthesis and photoluminescence properties of Mn<sup>4+</sup>-doped BaMg<inf>6</inf>Ti<inf>6</inf>O<inf>19</inf> phosphor 査読有り

    Sasaki, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Chemistry Letters 43 (7) 1061-1063 2014年

    出版者・発行元:CHEMICAL SOC JAPAN

    DOI: 10.1246/cl.140282  

    ISSN:1348-0715 0366-7022

    eISSN:1348-0715

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    A Mn4+-doped BaMg6Ti6O19 red phosphor was synthesized by a solid-state reaction. This phosphor showed red emission with a peak at 660 nm because of the E-2 -&gt; (4)A(2) transition of Mn4+ upon excitation in the region from near ultraviolet to blue. The specimen doped with 0.1% Mn and synthesized at 1250 degrees C exhibited the maximum emission intensity. BaMg6Ti6O19:Mn4+ is a novel red phosphor of titanate, which is the host material.

  69. Structure and Magnetic Property of FeAl<inf>2</inf>O<inf>4</inf> Synthesized by Microwave Heating 査読有り

    Fukushima, J., Hayashi, Y., Takizawa, H.

    Processing and Properties of Advanced Ceramics and Composites VI: Ceramic Transactions 249 293-301 2014年

    出版者・発行元:Wiley Blackwell

    DOI: 10.1002/9781118995433.ch28  

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    Most of microwave energy transforms into thermal energy, and chemical reactions are driven by thermal energy. In the past decade, however, many studies have been reported about "microwave effect", which is difficult to explain by thermodynamics, e.g., decrystallization of the ferromagnetic materials, creating the supersaturated solid solutions, etc. In particular, it is noteworthy of the antiferromagnetic-ferromagnetic transition of a spinel ferrite. Although it is known that the microwave magnetic field (H-field) plays an important role in this process, the details are still not clear. In previous work, FeAl&lt inf&gt 2&lt /inf&gt O&lt inf&gt 4&lt /inf&gt , which is a typical antiferromagnetic spinel, was synthesized using single-mode 2.45 GHz microwave H-field irradiation and the effect of the magnetic fields on magnetic characteristics of antiferromagnetic oxide was studied. However, the authors do not reach to reveal a basic mechanism of decreasing the crystal diameter (increasing the grain boundaries) by microwave irradiation. In the study, to examine the effect of the ratio of y-Fe&lt inf&gt 2&lt /inf&gt O&lt inf&gt 3&lt /inf&gt in starting materials for the change of magnetic properties by microwave H-field irradiation, FeAl&lt inf&gt 2&lt /inf&gt O&lt inf&gt 4&lt /inf&gt is synthesized from 90 wt% Fe&lt inf&gt 2&lt /inf&gt O&lt inf&gt 3&lt /inf&gt -10 wt% Al&lt inf&gt 2&lt /inf&gt O&lt inf&gt 3&lt /inf&gt mixed powder.

  70. Synthesis of Divalent Sn Compounds Under Microwave Non-Equilibrium Reaction Field 査読有り

    Takizawa, H., Sato, N., Fukushima, J., Hayashi, Y.

    Processing and Properties of Advanced Ceramics and Composites VI: Ceramic Transactions 249 321-328 2014年

    出版者・発行元:Wiley Blackwell

    DOI: 10.1002/9781118995433.ch31  

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    Chemical reaction between two or more components under microwave electromagnetic field is essentially "non-equilibrium reaction" because microwave absorbing behavior strongly depends on a nature of a material. Selective heating of a specific component plays a key role on the formation of non-equilibrium structure. The existence of stereoactive lone pair (5s&lt sup&gt 2&lt /sup&gt ) is an issue of concern of Sn&lt sup&gt 2+&lt /sup&gt compounds in a view point of ferroelectricity, however, it is difficult to synthesize Sn&lt sup&gt 2+&lt /sup&gt compounds because SnO tends to decompose to metallic Sn and Sn&lt sup&gt 4+&lt /sup&gt O&lt inf&gt 2&lt /inf&gt at elevated temperature. Binary SnO-TiO&lt inf&gt 2&lt /inf&gt system is a typical selective heating system under microwave irradiation because SnO strongly absorbs microwaves, but TiO&lt inf&gt 2&lt /inf&gt is nearly transparent to microwaves. During microwave irradiation to the powder mixture of SnO and TiO&lt inf&gt 2&lt /inf&gt , a drastic enhancement of reaction kinetics could be achieved under thermally non-equilibrium condition. This makes it possible to synthesize a non-equilibrium Sn&lt sup&gt 2+&lt /sup&gt compound, Sn&lt inf&gt 2&lt /inf&gt TiO&lt inf&gt 4&lt /inf&gt , avoiding the disproportionation reaction of SnO. Optimal synthetic condition to obtain a single-phase Sn&lt sup&gt 2&lt /sup&gt TiO&lt inf&gt 4&lt /inf&gt and the comparison with the other external rapid heating system was studied.

  71. New Scope to Microwave Special Effects on Chemical Reactions - Fundamental and Application - 招待有り 査読有り

    Yuji Wada, Hirotsugu Takizawa

    Proceedings of the 2nd Global Congress on Microwave Energy Applications 26-40 2013年7月

  72. マイクロ波と超音波を用いた金属ナノ粒子の固液系エコプロセッシング 招待有り 査読有り

    林 大和, 井上雅博, 森 貴洋, 福島潤, 滝澤博胤

    Proc. Mate2013 75-78 2013年1月29日

  73. 遠藤 忠先生のご逝去を悼む

    滝澤 博胤

    高圧力の科学と技術 23 (4) 347-347 2013年

    出版者・発行元:The Japan Society of High Pressure Science and Technology

    DOI: 10.4131/jshpreview.23.347  

    ISSN:0917-639X

  74. P27 超音波照射による銀ナノワイヤー前駆体の合成(ポスターセッション)

    菅原 賢太, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 22 75-76 2013年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.22.0_75  

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    Silver nanowire transparent conducting films (TCFs) are expected to be alternative materials for indium tin oxide TCFs. Silver nanowires are typically synthesized by polyol method. It requires protective agents in order to achieve an anisotropic crystal growth, however, protective agents cover the surface of nanowires, and hence decrease conductivity of electrodes. In this study, we have synthesized needle-shaped silver carboxylates by ultrasound irradiation without any protective agent, and then obtained silver nanowires by exposing them to hydrazine gas. Silver carboxylates were synthesized by ultrasound irradiation to mixture that contains silver(I) oxide, carboxylic acids(2-6C), and ethanol. These carboxylates were put onto glass substrate, and then exposed to hydrazine gas (vaporized hydrazine monohydrate) to reduce. The obtained samples were characterized by FE-SEM, XRD, TG-DTA, and UV-Vis. Long needle-shaped silver carboxylates were observed after ultrasound irradiation. In contrast to stirrer, we obtained well-dispersed silver carboxylates by ultrasound irradiation. In addition, it was confirmed that the reaction rate is greater than that of stirrer. These results are due to effects of ultrasound, such as strong dispersive power, erosion, and high temperature-pressure reaction field. Silver nanowire TCF were prepared by reducing silver carboxylates. This film indicated low resistivity and high transparency.

  75. A13 固液系超音波・マイクロ波反応場を利用した白金ナノ粒子の合成と応用(口頭発表)

    林 大和, 福島 潤, 滝澤 博胤, 國井 勝之

    ソノケミストリー討論会講演論文集 22 109-110 2013年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.22.0_109  

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    Ecology and Economy synthesis is important in the future. There are some elements to achieve this synthesis. One is a production device. A cheap device is hoped for in not an expensive, special device but the general purpose. The second is a raw material. When synthesizing, neither waste nor the air pollutant are not generated, and it is safe and nontoxic raw material is preferable. The third is a synthetic temperature. Low temperature synthesis as much as possible is suitable from the viewpoint of energy conservation. Sustainable processing for Platinum nanoparticles were developed by novel ultrasonic and microwave liquid-solid reaction. We used Platinum oxide as metallic source and water based solvent in this system. This system can be synthesized 2-3nm Platinum nanoparticle in short time and non-waste, so low-pricing of Platinum nanoparticle is realizable. By using water-ethanol mixed solvent, it can obtain dispersant-free Platinum nanoparticles suitable for catalyst, etc. In this study, fabricated conditions were examined in detail, reaction mechanisms and morphology of products were investigated.

  76. P28 固-液系超音波反応場を用いたAg/グラフェンナノコンポジットの合成と評価(ポスターセッション)

    望月 智文, 林 大和, 福島 潤, 滝澤 博胤

    ソノケミストリー討論会講演論文集 22 77-78 2013年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.22.0_77  

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    Recently, graphene has attracted tremendous research interest due to its unique mechanical, electrical and thermal properties caused by a two-dimensional, single-atom-thick structure of sp^2-bonded carbon atoms. In the past few years, several methods, such as chemical vapor deposition and chemical reduction of graphene oxide, have been used to prepare graphene sheets. It is known that chemical reactions, stirring, dispersion and exfoliation are promoted by ultrasound-cavitation. In this work, Graphite Oxide (GO) and Ag/graphene nanocomposites were synthesized by solid-liquid sonochemical reactions easily and briefly. GO was synthesized by means of Hummers method using sonication or stirring. From XRD patterns and FT-IR spectra, the oxidation of graphite was promoted by chemical and physical effects of ultrasound. Ag/graphene nanocomposites were synthesized from GO and silver oxide by sonication. UV-vis spectra showed the peaks of graphene oxide and Ag nanoparticle plasmon resonance absorption. EDX images and electron diffraction patterns confirmed Ag nanoparticles were decorated on graphenesheets by ultrasound. Using sonication, GO and Ag/graphene nanocomposites could be synthesized easily in short time.

  77. Eco-fabrication of metal nanoparticle related materials by non-equilibrium reaction field 査読有り

    Hayashi, Y., Sekiguchi, Y., Yamada, T., Takizawa, K., Koubu, H., Fukushima, J., Takizawa, H.

    Materials Science Forum 761 87-+ 2013年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.761.87  

    ISSN:1662-9752 0255-5476

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    Eco (Ecology & Economy)-fabrication is important in the future manufacturing. There are some elements to achieve this synthesis. When synthesizing, neither waste nor the air pollutant are not generated, and it is safe material is preferable with cheap fabrication device. We developed a new metal nanoparticle related materials synthesis method that achieved in these viewpoints. This new synthesis method is with microwave as non-equilibrium reactor and the metal oxide and alcohol-based solvent are used for the raw material. Moreover, the oxide and alcohol generally are cheap without toxicity. We synthesized metal nanoparticle related materials by microwave in liquid-solid (alcohol - metal oxide) slurry and controlled morphology of products. Microwave irradiation in liquid-solid process can be expected as chemical non-equilibrium and nonlinear reactors for metal nanoparticle related materials synthesis. The alcohol based solvent and the metal oxide powder are put in the beaker and only irradiated by ultrasound or microwave. The metal oxide simply was reduced into metal and morphology of metal nanoparticles was changed by various conditions. Various metal nanoparticle related materials were fabricated by microwave irradiation as non-equilibrium reaction field.

  78. Fabrication and thermoelectric properties of Al-doped (ZnO)<inf>5</inf>In<inf>2</inf>O<inf>3</inf> by microwave heating 査読有り

    Endo, T., Hayashi, Y., Fukushima, J., Takizawa, H.

    Materials Science Forum 761 27-31 2013年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.761.27  

    ISSN:1662-9752 0255-5476

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    Various (ZnO)5In2O3 ceramics were fabricated by microwave heating. Density, XRD pattern and microstructure were examined, and those of the Al-doped (ZnO)5In2O3 were almost the same as Al-free one. The highly textured (ZnO)5In2O3 ceramic was also fabricated by reactive templated grain growth (RTGG) method. The electrical conductivity was not improved by Al-doping however it was improved slightly by microwave heating compared with conventional heating and especially improved by texturing using RTGG method. On the other hand, the absolute Seebeck coefficient in microwave heating was improved about 25% by Al-doping. The maximum electric power factor of a textured specimen fabricated by RTGG method along the ab-plane showed 5.76×10-4 WK-2m-1 (at 873K), which was attributed to high electrical conductivity. © (2013) Trans Tech Publications, Switzerland.

  79. Synthesis of aluminium nitride under 2.45 GHz microwave irradiation 査読有り

    Tamba, Y., Hayashi, Y., Takizawa, H.

    International Journal of Nanotechnology 10 (1-2) 63-70 2013年

    出版者・発行元:INDERSCIENCE ENTERPRISES LTD

    DOI: 10.1504/IJNT.2013.050882  

    ISSN:1475-7435

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    Aluminium nitride (AlN) is a functional ceramic which has several properties, and it is applied to substrate materials and fillers for packaging materials of electronic devices. Microwave heating has characteristics such as internal heating, rapid heating and selective heating, so it is useful for synthesis of ceramics. In this work, spherical AlN particles were synthesised by carbothermal reduction and nitridation of Al2O3 under 2.45 GHz microwave irradiation. The mixture of spherical Al2O3 particles and carbon was used as the starting materials. Carbon absorbed microwaves selectively, and the starting materials were heated rapidly in flowing nitrogen gas. Al2O3 was converted to AlN in a short time; and finally, polycrystalline spherical AlN particles were successfully formed. They retained particle diameters of spherical Al2O3 particles used as the starting material.

  80. In-situ kinetic study on non-thermal reduction reaction of CuO during microwave heating 査読有り

    Fukushima, J., Kashimura, K., Takayama, S., Sato, M., Sano, S., Hayashi, Y., Takizawa, H.

    Materials Letters 91 252-254 2013年

    DOI: 10.1016/j.matlet.2012.09.114  

    ISSN:0167-577X

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    Reduction kinetics of CuO during microwave heating and conventional heating (electric furnace) were investigated to verify a process of direct transforming microwave energy into energy of reduction reaction. In the experiment, reduction speed during microwave heating or conventional heating was analyzed from an amount of emitted oxygen from a sample. An activation energy in each heating was obtained from an Arrhenius plot of the results. The activation energy in microwave heating at the maximum point of E-field (E-field heating) was decreased to 2/3 that in conventional one and the activation energy in microwave heating at the maximum point of H-field (H-field heating) was also decreased to 1/3 compared to that in conventional one. As the sample was reduced to Cu2O, microwave energy is transformed directly into reduction energy because the enthalpy of the reduction reaction is larger than activation energies in E-field and H-field heating. © 2012 Elsevier B.V. All rights reserved.

  81. Structure and magnetic properties of FeAl <inf>2</inf> O <inf>4</inf> synthesized by microwave magnetic field irradiation 査読有り

    Fukushima, J., Hayashi, Y., Takizawa, H.

    Journal of Asian Ceramic Societies 1 (1) 41-45 2013年

    出版者・発行元:Elsevier B.V.

    DOI: 10.1016/j.jascer.2013.02.001  

    ISSN:2187-0764

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    The structure and magnetic properties of FeAl2O4 synthesized by microwave magnetic field (H-field) irradiation were investigated to reveal the effect of the H-field on the crystal structure and the magnetic characteristics of an antiferromagnetic material. The role of the H-field was investigated using a single-mode cavity, which can spatially separate the maximum points of the alternating electric field (E-field) and H-field in the cavity. In H-field irradiation, the crystallite diameter decreased compared to that in conventional heating. In conventional heating, the crystallite diameter did not change with increasing quenching speed. Thus, it is suggested that a decrease in crystallite diameter occurs during H-field irradiation. Furthermore, magnetization after H-field irradiation was greater than that after conventional heating. It is considered that magnetic clusters appear when Fe3+ partially replaces Al3+ in the octahedral sites in the grain boundaries, which were formed as a result of decreasing crystallite diameter. © 2013 The Ceramic Society of Japan and the Korean Ceramic Society.

  82. Fabrication of (Zn<inf>1-x</inf>Al<inf>x</inf>O)<inf>5</inf>In <inf>2</inf>O<inf>3</inf> by microwave irradiation and thermoelectric characterization 査読有り

    Endo, T., Fukushima, J., Hayashi, Y., Takizawa, H.

    Journal of the Ceramic Society of Japan 121 (1413) 416-421 2013年

    出版者・発行元:Ceramic Society of Japan

    DOI: 10.2109/jcersj2.121.416  

    ISSN:1348-6535 1882-0743

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    The layer-structured thermoelectric material, Al-doped (ZnO) 5In2O3, was fabricated by microwave irradiation within a short time of 15min and its thermoelectric properties were examined. When comparing specimens sintered by microwave irradiation (15 min) with those by conventional heating (4h), their microstructure and composition were similar. However, electrical conductivity was improved by microwave irradiation. Moreover, in (Zn1-xAlxO)5In2O 3 (x = 0.016, 0.032), Al-doping contributed to an increase in both the electrical conductivity and the absolute value of Seebeck coefficient, which contributed fairly to the high dimensionless figure of merit, ZT. Larger ZT was achieved by improvement in electrical conductivity by microwave irradiation and increases in both the electrical conductivity and the absolute value of Seebeck coefficient by Al doping. (Zn0.984Al0.016O) 5In2O3 sintered by microwave irradiation had the highest ZT, which was 1.5 times higher than that of (ZnO)5In 2O3 sintered by conventional heating at 773 K. © 2013 The Ceramic Society of Japan. All rights reserved.

  83. Synthesis of noble metal-doped Cu nanoparticles by ultrasonication 査読有り

    Koubu, H., Hayashi, Y., Fukushima, J., Takizawa, H., Narita, I., Yoshioka, S.

    Materials Transactions 54 (8) 1496-1501 2013年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.M2013077  

    ISSN:1345-9678

    eISSN:1347-5320

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    Cu nanoparticles doped with small amounts of noble metals were synthesized by ultrasonication. The noble metals selected were Pd, Pt, Ru, Rh and Ir. Mean particle size was most reduced for Cu nanoparticles doped with Pd, with Cu-Pd nanoparticles of approximately 50 urn in diameter being obtained. X-ray absorption, near-edge spectroscopy and extended X-ray absorption were used to conduct fine structure analysis, and these techniques confirmed that Cu-Pd nanoparticles possessed Cu-Pd bonds. High-angle annular dark-field scanning transmission electron microscopy and energy dispersive X-ray spectrometer mapping were used to show that Cu-Pd nanoparticles were dispersed as Pd clusters inside Cu nanoparticles. It was supposed that the surfaces of Cu-Pd nanoparticles were Cu-rich, and Pd clusters were dispersed inside these particles. It is proposed that heterogeneous nucleation of Cu onto Pd nuclei resulted when nucleation of Pd occurred.

  84. 固液系超音波反応場を用いた金属ナノ粒子材料の合成 招待有り 査読有り

    林 大和, 講武裕朗, 瀧澤 洸, 関口和大, 山田雄大, 樋澤健太, 滝澤博胤, 井上雅博

    Proc. Mate2012 159-162 2012年1月31日

  85. Effect of Amplitude Modulation of Microwave on Non-thermal Reduction of Copper Oxides 査読有り

    J. Fukushima, M. Sato, K. Kashimura, T. Mitani, Y. Hayashi, H. Takizawa

    Proc. of the 2nd Global Congress on Microwave Energy Applications 242-252 2012年

    詳細を見る 詳細を閉じる

    ISBN:978-0-9786222-1-3

  86. Effect of H-field or E-field on sintering and decrystallization of titanium oxides during 2.45 GHz microwave heating 査読有り

    Fukushima, J., Takayama, S., Sano, S., Sato, M., Hayashi, Y., Takizawa, H.

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 59 (9) 553-556 2012年

    DOI: 10.2497/jjspm.59.553  

    ISSN:0532-8799

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    The effect of an H-field or E-field on the sintering and decrystallization of titanium oxides during 2.45 GHz microwave heating was investigated. Titanium oxides (TiO2-x) were heated in a TE103 single-mode cavity, which was used to separate the maximum point of the H-field or E-field of the 2.45 GHz microwave radiation. Scanning electron microscopy (SEM) images taken after H-field heating showed that the sample was sintered well above 1400 °C. In the X-ray diffraction (XRD) patterns, the intensity of the diffraction peaks of TiO2 decreased with increasing heating temperature between 1200°C and 1400 °C. After heating at 1500°C, however, the TiO2 peak intensities increased and undefined peaks emerged. Decrystallization is the dominant reaction, driven by the nonthermal microwave effect, below 1400°C. As the effect of the thermal energy becomes larger than the nonthermal microwave effect above 1500°C, grain growth becomes the dominant reaction. During E-field heating, the surface structure changes to fiber-like and dot-like structures, while some areas are oxidized by plasma excited by the microwaves.

  87. Eco-fabrication of noble metal nanoparticle related materials by liquid-solid ultrasonic reaction 査読有り

    Y. Hayashi, M. Inoue, H. Takizawa, K. Suganuma

    ICEP 2011 Proceedings 320-323 2011年4月

  88. Fabrication and Application of Ag Nanoparticles by Ultrasonic Process 査読有り

    D. Ishikawa, T. Abe, K.Toisawa, Y. Hayashi, H. Takizawa

    ICEP 2011 Proceedings 330-335 2011年4月

  89. 固液系超音波反応場を用いた金属ナノ粒子およびその複合体の製造プロセス 招待有り 査読有り

    井上雅博, 林 大和, 山田雄大, 関口和大, 滝澤博胤

    Proc. Mate2011 85-88 2011年2月4日

  90. Thermal Transport Properties of Ag-Based Nanocomposites Containing MWCNTs 査読有り

    Masahiro Inoue, Yamato Hayashi, Hirotsugu Takizawa

    MRS Online Proceedings Library 1404 9-14 2011年

    DOI: 10.1557/opl.2012.253  

    ISSN:0272-9172

  91. Synthesis of Palladium nanoparticles and palladium/spherical carbon composite particles in the solid-liquid system of palladium oxide-alcohol by microwave irradiation 査読有り

    Sekiguchi, Y., Hayashi, Y., Takizawa, H.

    Materials Transactions 52 (5) 1048-1052 2011年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.M2010429  

    ISSN:1345-9678

    eISSN:1347-5320

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    Palladium nanoparticles were synthesized in the solid liquid system of palladium oxide alcohol by microwave irradiation. They were compared with those produced by a conventional heating method. We also used various alcohol solvents and compared the products obtained. The products contained particles that had diameters of several nanometers. In these measurements, microwave heating produced smaller particles than conventional heating because it provided homogeneous and direct heating. Additionally, Pd/spherical carbon (SC) composite particles could be prepared by the same method. For microwave heating, SC particles can support palladium particles without calcination, which is due to selective heating by microwaves. [doi:10.2320/matertrans.M2010429]

  92. Solid-state synthesis of Sn<inf>2</inf>TiO<inf>4</inf>: A new synthetic strategy for direct synthesis of sn<sup>2+</sup> compounds using microwave irradiation 査読有り

    Ohara, S., Takizawa, H., Hayashi, Y.

    Chemistry Letters 39 (4) 364-365 2010年

    出版者・発行元:CHEMICAL SOC JAPAN

    DOI: 10.1246/cl.2010.364  

    ISSN:0366-7022 1348-0715

    eISSN:1348-0715

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    Divalent tin compound, Sn2TiO4, was synthesized by a simple solid-state reaction of component oxides under 2.45 GHz microwave irradiation. The reaction rapidly proceeds with the diffusion of hot Sn2+ species toward TiO2 to form Sn2TiO4 within 1 min. A drastic enhancement of reaction kinetics could be achieved under thermally nonequilibrium conditions induced by strong coupling of SnO with microwave energy. This makes it possible to avoid the disproportionation reaction of SnO to Sn and SnO2, giving us a new synthetic strategy for direct synthesis of Sn2+ compounds.

  93. Superconducting properties of SmFeAsO<inf>1-x</inf> prepared under high-pressure condition 査読有り

    Ju, J., Huynh, K., Tang, J., Li, Z., Watahiki, M., Sato, K., Terasaki, H., Ohtani, E., Takizawa, H., Tanigaki, K.

    Journal of Physics and Chemistry of Solids 71 (4) 491-494 2010年

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.jpcs.2009.12.019  

    ISSN:0022-3697

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    Synthetic conditions such as stoichiometries, temperature and pressure are optimized to achieve a high quality oxygen deficient SmFeAsO0.6 superconductor. Both electric and magnetic measurements show a sharp superconducting transition at about 55 K. Several important physical parameters are deduced. The apparent superconducting gap observed in heat capacity with 2 Delta(o)/k(B)T(c) of 4.57 larger than that of previous fluorine replaced samples indicate that this superconductivity will not strongly conflict with the phonon-mediated BCS mechanism. The mean free length l = 18.8 nm and the coherent length xi = 2.3-3.3 nm show that the superconductivity is in the clean limit. (C) 2009 Elsevier Ltd. All rights reserved.

  94. High-pressure synthesis of a new ferromagnetic compound, CrGa<inf>2</inf>Sb<inf>2</inf> 査読有り

    Sakakibara, W., Hayashi, Y., Takizawa, H.

    Journal of Alloys and Compounds 496 (1-2) L14-L17 2010年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/j.jallcom.2010.01.158  

    ISSN:0925-8388

    詳細を見る 詳細を閉じる

    A new intermetallic compound, CrGa2Sb2, has been synthesized by a direct reaction from Cr and GaSb at 6.3 GPa and 600 degrees C using a belt-type high-pressure apparatus. The compound crystallizes into an orthorhombic MnGe4-type structure with the space group Iba(2) (no. 45). The structure was refined by the Rietveld analysis of the powder X-ray diffraction data and the lattice constant was determined to be a = 1.1781(5) nm, b = 0.5968(2) nm, c = 0.5902(2) nm. The structure consists of -Cr-Cr-Cr- linear chains parallel to the c-axis. The compound exhibits an itinerant-electron ferromagnetic behavior with the Curie temperature of 345 K. (C) 2010 Elsevier B.V. All rights reserved.

  95. Synthesis of natural superlattice structure in the binary ZnO-Fe <inf>2</inf>O<inf>3</inf> system by microwave irradiation 査読有り

    Katayose, S., Miyazaki, T., Hayashi, Y., Takizawa, H.

    Journal of the Ceramic Society of Japan 118 (1377) 387-389 2010年

    出版者・発行元:CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

    DOI: 10.2109/jcersj2.118.387  

    ISSN:1348-6535 1882-0743

    eISSN:1348-6535

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    Homologous compounds, Fe2O3(ZnO)(m), with the modulated natural superlattice structure were obtained within a short period by solid state reaction of component oxides under 2.45 GHz microwave irradiation. TEM observation revealed that two types of superlattice structures were observed in different Fe concentration; one is longitudinal superlattice structure in a rod shaped precipitation at high Fe concentration, and the other is modulated structure showing zigzag shape at low Fe concentration. It is conclude that the non-equilibrium nature of microwave selective heating, as well as rapid heating and quenching effects, plays a key role to form the superstructure. The obtained products exhibit ferromagnetic behavior with the Curie temperature above 300 K. (C) 2010 The Ceramic Society of Japan. All rights reserved.

  96. Formation mechanism of nanostructured Ag films from Ag<inf>2</inf>O particles using a sonoprocess 査読有り

    Inoue, M., Hayashi, Y., Takizawa, H., Suganuma, K.

    Colloid and Polymer Science 288 (10-11) 1061-1069 2010年

    出版者・発行元:Springer Verlag

    DOI: 10.1007/s00396-010-2240-8  

    ISSN:0303-402X

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    Nanostructured Ag films composed of nanoparticles and nanorods can be formed by the ultrasonication of ethanol solutions containing Ag2O particles. The present work examined the formation process of these films from ethanol solutions by two different agitation methods, including ultrasonication and mechanical stirring. The mass-transfer process from Ag2O particles to ethanol solvent is accelerated by the mechanical effects of ultrasound. Ag+ ions and intermediately reduced Ag clusters were released into the ethanol. These Ag+ ions and Ag clusters provide absorption bands at 210, 275 and 300 nm in UV-vis spectra. These bands were assigned to the absorption of Ag+, Ag42+ and Agn (n≈3). The Agn clusters that readily grow to become Ag nanoparticles were formed due to the surface reaction of Ag2O particles with ethanol under ultrasonication. The reactions of Ag+ ions in ethanol to form Ag nanomaterials (through the formation of Ag 42+ clusters) were also accelerated by ultrasonication. © Springer-Verlag 2010.

  97. Synthesis of highly concentrated Ag nanoparticles in a heterogeneous solid-liquid system under ultrasonic irradiation 査読有り

    Toisawa, K., Hayashi, Y., Takizawa, H.

    Materials Transactions 51 (10) 1764-1768 2010年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.MJ201005  

    ISSN:1345-9678

    eISSN:1347-5320

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    Ag nanoparticles were synthesized at a high concentration (about 10-100 times higher than traditional process) without condensation by ultrasonic irradiation of a heterogeneous solid liquid system This process offers reduced costs of condensation of the prepared solution and waste liquid treatment compared to the traditional process Besides Ag conductive films were prepared with a relatively good electrical resistivity of 3 30 mu Omega cm after brief low temperature sintering [dot 10 2320/matertrans MJ201005].

  98. Synthesis of carbon nanotube/silver nanocomposites by ultrasonication 査読有り

    Yamada, T., Hayashi, Y., Takizawa, H.

    Materials Transactions 51 (10) 1769-1772 2010年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.MJ201012  

    ISSN:1345-9678

    eISSN:1347-5320

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    Carbon nanotube (CNT)/Ag nanocomposites were synthesized by an ultrasonic process Dispersion of aggregated CNTs and synthesis of both Ag nanoparticles and Ag/CNT composite particles were executed by ultrasonic treatment Dispersibility of Ag nanoparticles improved with the combined use of a dispersant which led to improved densification upon sintering In addition synthesis of nanosize Ag particles allowed sintering of the CNT/Ag nanocomposites at 300 degrees C with a resulting electrical resistivity of 2 46 mu Omega cm [doi 10 2320/matertrans MJ201012].

  99. Equal channel angular extrusion technique for controlling the texture of n-Type Bi<inf>2</inf>Te<inf>3</inf> based thermoelectric materials 査読有り

    Hayashi, T., Horio, Y., Takizawa, H.

    Materials Transactions 51 (10) 1914-1918 2010年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.M2010065  

    ISSN:1345-9678

    eISSN:1347-5320

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    The repetitive equal channel angular extrusion (ECAE) technique was applied to prepare n type Bi-1 Sb-9(0) Te-1(2) Se-7(0) (3) thermoelectric materials prepared from rapidly solidified and stacked foils Each ECAE process was performed at temperatures ranging from 693 to 773 K in an argon atmosphere The number of passes in the ECAE process was varied up to 6 passes via route C-y The texture of the specimens after ECAE was observed using an Orientation Imaging Microscopy (OIM) Observing the texture revealed that basal planes are satisfactory aligned and that the direction of the basal planes tends to rotate in the extrusion direction with an increasing number of passes A highly orientated texture was gradually formed by repetitive ECAE processing Both the number of passes and extrusion temperature were found to affect the texture characteristics Formation of twin boundaries in the initial stage of the repetitive ECAE plays a key role in releasing the shear strain imposed during ECAE operation A strongly orientated texture was observed in the specimen after 6 passes of ECAE via route Cy extruded at 773 K The grain size of the specimen after ECAE however was found to be unrelated to the number of passes The average grain size was within the range 9 0 to 19 2 pm in specimens extruded at 693 to 773 K Measurements of thermoelectric properties revealed that carrier mobility was strongly dependent on the degree of orientation Results also showed that a higher power factor of 4 01 x 10(-3) Wm(-1) was measured mainly due to increased earner mobility The Z value of the specimen after 6 passes of ECAE via route C-y at 773 K reached 3 04 x 10(-3) K-1 This result indicates that the ECAE technique largely improves thermoelectric properties of bismuth telluride based compounds [doi 10 2320/matertrans M2010065]

  100. マイクロ波照射によるTiN, TiCNコーティング膜の作製 査読有り

    宮下耕平, 林 大和, 滝澤博胤

    粉体および粉末冶金 57 (12) 753-757 2010年

    DOI: 10.2497/jjspm.57.753  

    ISSN:0532-8799

  101. Eco-fabrication of noble metal nanoparticles by metal oxide and home electronics appliances 査読有り

    Y. Hayashi, M. Inoue, I. Narita, K. Toisawa, T. Yamada, Y. Sekiguchi, H. Takizawa, K. Suganuma

    Proc. ICEP2009 887-890 2009年4月

  102. MnGa<inf>2</inf>Sb<inf>2</inf>, a new ferromagnetic compound synthesized under high pressure 査読有り

    Sakakibara, W., Hayashi, Y., Takizawa, H.

    Journal of the Ceramic Society of Japan 117 (1361) 72-75 2009年

    出版者・発行元:CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

    DOI: 10.2109/jcersj2.117.72  

    ISSN:1348-6535 1882-0743

    eISSN:1348-6535

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    A new intermetallic compound, MnGa2Sb2, has been synthesized by direct reaction from Mn and GaSb at 6 GPa and 500 degrees C for 30 min using a belt-type high pressure apparatus. The compound crystallizes into an orthorhombic structure with the space group Iba2 (No. 45). The structure was refined by the Rietveld analysis of the powder X-ray diffraction data and the lattice constant was determined to be a = 1.180(7) nm, b = 0.5968(2) nm, c = 0.5858(2) nm. The structure consists of -Mn-Mn-Mn- linear chains parallel to the c-axis. The compound exhibits metallic conductivity and itinerant-electron ferromagnetic behavior with the Curie temperature of 310 K. (C)2009 The Ceramic Society of Japan. All rights reserved.

  103. Preparation of barium titanate powders by microwave-assisted liquid phase process at ambient pressure 査読有り

    Matoba, R., Hayashi, Y., Takizawa, H.

    Journal of the Ceramic Society of Japan 117 (1363) 388-391 2009年

    出版者・発行元:CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

    DOI: 10.2109/jcersj2.117.388  

    ISSN:1348-6535 1882-0743

    eISSN:1348-6535

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    Fine barium titanate (BaTiO3) powders were prepared by a microwave-assisted liquid phase process at ambient pressure. The process is simple, ecologically friendly, and economical. Titanium dioxide (TiO2) and Barium hydroxide octahydrate (BaOH2 center dot 8H(2)O) were the only starting materials used, in order to avoid contamination. BaTiO3 powders were obtained as a single cubic phase from both microwave-assisted and conventional liquid phase processes. BaTiO3 powders synthesized by conventional liquid phase process were nonuniform in size. In contrast, BaTiO3 powders made by the microwave-assisted process consisted of fine uniform particles with a narrow size distribution. TGA analysis revealed that the lattice OH group content in BaTiO3 powders synthesized by the microwave-assisted process decreased with increasing reaction time. (C) 2009 The Ceramic Society of Japan. All rights reserved.

  104. Synthesis and microstructural control of Ln<inf>2</inf>O <inf>3</inf>(ZnO)<inf>3</inf> layered compound by microwave-heating 査読有り

    Yanagiya, S., Hayashi, Y., Takizawa, H.

    Materials Science Forum 620 622 85-88 2009年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.620-622.85  

    ISSN:1662-9752 0255-5476

    詳細を見る 詳細を閉じる

    In(2)O(3)(ZnO)(3) layered compound was synthesized by 2.45 GHz microwave heating in a solid state reaction. Microwave-processed samples were obtained at low temperature by the enhancement of solid state diffusion and sublimation of the powder bed. Plate-like grain microstructures formed on the bottom part of the pellet, and vicinity of the surface was dense. The plate-like grain was oriented in the ab-plane direction. Compared with a conventional heated sample, the electrical conductivity increased and the band gap energy decreased. In the case of deposition on a silica substrate by microwave heating, the plate-like grain film was synthesized.

  105. Eco-fabrication of metal nanoparticle related materials by home electric appliances 査読有り

    Hayashi, Y., Inoue, M., Narita, I., Suganuma, K., Takizawa, H.

    Materials Science Forum 620 622 185-+ 2009年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/www.scientific.net/MSF.620-622.185  

    ISSN:1662-9752 0255-5476

    詳細を見る 詳細を閉じる

    Applications of various noble metal nanoparticles were investigated for newly, ecology and economy home electric appliances (microwave, ultrasonic) used system. Noble metal oxides have merit in metal particles fabrication, as one of these example example, there are decomposed by only heating in air. That is, noble metal oxide don't use strong reduction atmosphere. This reduction is ecologically clean, because many noble metal oxides are not toxic and during decomposition O-2 is evolved. We have reduced noble metal oxides by microwave and ultrasound, and tried to fabricate noble metal nanoparticles, and investigated various processing. These energy are widely used by home electric appliances. By choosing suitable process and conditions, it is reasonable to expect that home electric appliances ecology and economy fabrications can be extended to obtain simply various noble metal nanoparticles related materials.

  106. The effects of microwave heating on the formation of SnO<SUB>2</SUB> thin films coated by sol-gel method 査読有り

    T. Yonezawa, Y. Hayashi, H. Takizawa

    2008 Global Congress on Microwave Energy Applications Proceedings 685-688 2008年8月

  107. Orientation Control of Layered BaFe<SUB>12</SUB>O<SUB>19</SUB> Polycrystalline by Microwave Irradiation 査読有り

    T. Takayanagi, Y. Hayashi, H. Takizawa

    2008 Global Congress on Microwave Energy Applications Proceedings 699-702 2008年8月

  108. Microwave Synthesis and Magnetic Properties of Spinel-Type ZnFe<SUB>2</SUB>O<SUB>4</SUB> 査読有り

    Satomi Katayose, Yamato Hayashi, Hirotsugu Takizawa

    2008 Global Congress on Microwave Energy Applications Proceedings 719-722 2008年8月

  109. Microstructural control of the TiO<inf>2</inf>-SnO<inf>2</inf> binary system and synthesis of SnO<inf>2</inf> nanowhiskers by microwave irradiation 査読有り

    Aoyagi, T., Hayashi, Y., Takizawa, H.

    Materials Transactions 49 (4) 879-884 2008年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.MER2007327  

    ISSN:1345-9678

    eISSN:1347-5320

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    SnO2 single crystals (columnar crystals and silver grass-like nanowhiskers) were synthesized by selective microwave heating of a TiO2-SnO2 mixture. The shape of the as-grown SnO2 crystals is strongly dependent on the atmosphere during microwave irradiation. This is due to the difference in growth mechanisms, as revealed by in-situ surface observation under microwave irradiation, in addition to scanning and transmission electron microscopy observations of irradiated specimens. In a N-2 atmosphere, silver grass-like SnO2 nanowhiskers were obtained. On the other hand, columnar SnO2 crystals were obtained in air or an O-2 atmosphere. Photoluminescence and absorption spectra of the as-grown SnO2 crystals were examined. Based on the analysis of a TiO2-SnO2 pellet, it was found that the bottom was selectively heated, and SnO2 sublimated by microwave irradiation. A density gradient texture of the sample pellet was formed.

  110. Preparation of mesoscopic TiO<inf>2</inf>-SnO<inf>2</inf> composite grains by spinodal decomposition under 28 GHz microwave irradiation 査読有り

    Takizawa, H., Hagiya, A., Aoyagi, T., Hayashi, Y.

    Chemistry Letters 37 (7) 714-715 2008年

    出版者・発行元:CHEMICAL SOC JAPAN

    DOI: 10.1246/cl.2008.714  

    ISSN:0366-7022

    eISSN:1348-0715

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    TiO2-SnO2 composite with the modulated lamellar structure was obtained within a short period by microwave irradiation using 28-GHz frequency. Single-phase solid solution with the rutile-type structure was formed at the early stage of irradiation, and the prolonged irradiation caused the formation of mesoscopic lamellar structure induced by spinodal decomposition. Such a nonequilibrium nature is believed to be due to selective heating behavior under microwave irradiation.

  111. Preparation of platinum nanoparticles in heterogeneous solid-liquid system by ultrasound and microwave irradiation 査読有り

    Ishikawa, D., Hayashi, Y., Takizawa, H.

    Journal of Nanoscience and Nanotechnology 8 (9) 4482-4487 2008年

    出版者・発行元:AMER SCIENTIFIC PUBLISHERS

    DOI: 10.1166/jnn.2008.298  

    ISSN:1533-4880

    詳細を見る 詳細を閉じる

    Pt nanoparticles and Pt/spherical carbon (SC) were prepared in a heterogeneous (PtO2/SC, water/ethanol) solid-liquid system without dispersant using ultrasound and microwave irradiation. The Pt nanoparticles and Pt/SC were characterized using X-ray diffraction (XRD), transmission electron microscopy-energy-dispersive X-ray spectroscopy (TEM-EDX), and dynamic light scattering method for particle size determination. The average size of the Pt nanoparticles prepared by only ultrasound irradiation was smaller than that prepared by microwave irradiation. Pt nanoparticles were successfully prepared by microwave irradiation with a reaction time of several minutes at a specific concentration of diluted ethanol. Pt/SC prepared by combined ultrasound and microwave irradiation resulted in fine particles with good homogeneous distribution.

  112. S1-3 Decomposition behaviour and morphology change of noble metal oxide by ultrasonic irradiation(Symposium (1) Sonochemical Innovation in Materials Processing)

    Hayashi Yamato, Inoue Masahiro, Suganuma Katsuaki, Narita Ichihito, Takizawa Hirotsugu

    ソノケミストリー討論会講演論文集 2007 33-33 2007年

    出版者・発行元:日本ソノケミストリー学会

    DOI: 10.20577/pamjss.2007.suppl.0_33  

  113. Effects of 28 GHz/2.45 GHz microwave irradiation on the crystallization of blast furnace slag 査読有り

    Kuroki, T., Uchida, Y., Takizawa, H., Morita, K.

    ISIJ International 47 (4) 592-595 2007年

    出版者・発行元:IRON STEEL INST JAPAN KEIDANREN KAIKAN

    DOI: 10.2355/isijinternational.47.592  

    ISSN:0915-1559

    詳細を見る 詳細を閉じる

    The effects of microwave irradiation on the crystallization of 40%CaO-40%SiO2-2O%A1(2)O(3) synthesized slag and actual blast furnace slag were investigated using a 28GHz multimode microwave irradiation system, a commercial microwave oven (2.45GHz), and an electric resistance furnace. While it was observed that the 2.45 GHz centimeter-wave had little effect on the samples, the 28 GHz millimeter-wave was found to accelerate crystallization significantly, especially at lower temperatures at which the crystalline phases are never generated by external heating. Further, the effects of the precipitated phases and impurities on the crystallization with the 28GHz microwave irradiation were investigated. The temperature of the glassy slag increased more rapidly when compared with the crystalline phases that exist in the actual blast furnace slag. In addition, a small amount of impurity was found to improve the heating property of the slags.

  114. High-pressure synthesis of a new copper thioborate, CuBS<inf>2</inf> 査読有り

    Kajiki, T., Hayashi, Y., Takizawa, H.

    Materials Letters 61 (11-12) 2382-2384 2007年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/j.matlet.2006.09.018  

    ISSN:0167-577X

    詳細を見る 詳細を閉じる

    A new copper thioborate, CuBS2, was synthesized at high-pressure/temperature condition of 3 GPa and 700-900 degrees C. The crystal structure was refined by the Rietveld analysis of the powder X-ray diffraction data. The compound crystallizes into a tetragonal unit cell (a=0.5044(1) nm, c=0.8947(2) nm, space group: I-42d), isostructural with CuMS2 chalcopyrite compounds (M: Al, Ga, and In). The compound is the first representative of the chalcopyrite-type family consisting of BS4-tetrahedra. From the UV-Vis diffuse reflectance spectrum, the optical band gap of CuBS2, was estimated to be E-g=3.61 eV. (c) 2006 Elsevier B.V. All rights reserved.

  115. キレート剤を用いた高活性Co/SiO<SUB>2</SUB> Fischer-Tropsch合成触媒の調製:調製の各過程におけるCo種の構造に及ぼすキレート剤の影響 査読有り

    望月剛久, 小泉直人, 濱邊雄輔, 原 毅, 滝澤博胤, 山田宗慶

    石油学会誌 50 (5) 262-271 2007年

    出版者・発行元:None

    DOI: 10.1627/jpi.50.262  

    ISSN:1346-8804 1349-273X

  116. Application of 28 GHz microwave irradiation to oxidation of ilmenite ore for new rutile extraction process 査読有り

    Itoh, S., Suga, T., Takizawa, H., Nagasaka, T.

    ISIJ International 47 (10) 1416-1421 2007年

    出版者・発行元:IRON STEEL INST JAPAN KEIDANREN KAIKAN

    DOI: 10.2355/isijinternational.47.1416  

    ISSN:0915-1559

    詳細を見る 詳細を閉じる

    Microwave heating has been applied to the oxidation in the new rutile extraction process developed by the authors in which rutile is extracted from a natural ilmenite ore by oxidation and magnetic separation followed by leaching with diluted acid. Since ilmenite FeTiO3 and pseuclobrookite Fe2TiO5 strongly absorb 28 GHz microwave, Australian ilmenite ore mainly composed of FeTO3 was rapidly heated up to about 1 273 K and oxidized in air with keeping almost constant temperature. As a result, two equilibrium phases of rutile TiO2 and pseuclobrookite were quickly formed at microwave power of 1.5 kW. The growth rate of the pseudobrookite phase in the microwave irradiation was found to be much faster than that of the rutile phase in the conventional resistance furnace, indicating a drastic enhancement of the growth rate by the microwave irradiation.

  117. Thermoelectric and mechanical properties of angular extruded Bi <inf>0.4</inf>Sb<inf>1.6</inf>Te<inf>3</inf> compounds 査読有り

    Hayashi, T., Sekine, M., Suzuki, J., Horio, Y., Takizawa, H.

    Materials Transactions 48 (10) 2724-2728 2007年

    出版者・発行元:JAPAN INST METALS

    DOI: 10.2320/matertrans.MRA2007114  

    ISSN:1345-9678

    eISSN:1347-5320

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    P-type Bi0.4Sb1.6Te3 thermoelectric materials were prepared by an angular extrusion technique with rapidly solidified and stacked foils in a temperature range from 643 K to 838 K. Textures of the angular-extruded specimens were observed by Orientation Imaging Microscopy (OIM). The average grain size was monotonously enlarged from 4.7 to 16.1 mu m while increasing the extrusion temperature. The texture of the angular-extruded specimens shows that the basal planes are preferably aligned along the extrusion direction. Strong textures were observed in specimens extruded at a temperature range from 683 K to 803 K. The carrier mobility of the extruded specimens depends strongly on both the texture strength and grain size. As the extrusion temperature rises, the bending strength decreases. This change in bending strength is in good agreement with the Hall-Petch relationship. A maximum Z value of 3.33 x 10(-3) K-1 and bending strength of 80.3 MPa were achieved in a specimen angular-extruded at 773 K. The Z value and the bending strength were sufficiently high compared with conventional hot-extruded or hot-pressed specimens. These results indicate that the angular extrusion technique is effective in improving the thermoelectric and mechanical properties of bismuth-telluride based thermoelectric materials.

  118. Morphology control of silver related materials by ultrasonic irradiation 査読有り

    Sawada, K., Hayashi, Y., Takizawa, H.

    Journal of the Ceramic Society of Japan 115 (1348) 934-937 2007年

    出版者・発行元:CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

    DOI: 10.2109/jcersj2.115.934  

    ISSN:1348-6535 1882-0743

    eISSN:1348-6535

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    We synthesized needle-shaped Ag2CO3 and triangular plates of Ag by applying ultrasonic irradiation to the solid-liquid system, Ag2O/H2O. The samples obtained were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and inductively coupled plasma emission spectrometry (ICPES). The ICPES data confirmed that ultrasonic irradiation increased the solubility of Ag2O in distilled water. Applying low-frequency ultrasonic irradiation accelerated the dissolution of Ag2O and enabled needle-shaped Ag2CO3 and the triangular plate of Ag to be obtained by freeze-drying, while applying high-frequency ultrasonic irradiation almost reduced Ag2O to Ag. A variety of silver related materials could be synthesized using this water-based ultrasonic process that was environmentally friendly without adding a surfactant.

  119. Fabrication and applications of nano-metal particle composites by ultrasonic eco-process 査読有り

    Hayashi, Y., Takizawa, H., Saijo, Y., Sekino, T., Suganuma, K., Niihara, K.

    Key Engineering Materials 317-318 231-234 2006年

    出版者・発行元:Key Engineering Materials

    DOI: 10.4028/www.scientific.net/kem.317-318.231  

    ISSN:1662-9795 1013-9826

    詳細を見る 詳細を閉じる

    Nano-sized metal particles have recently attracted considerable interest owing to their application potential. Such particles can be synthesized using physical and chemical methods. In this study, nano-sized noble metals were synthesized through the reaction of metal oxides by ultrasonic. This means that the chemical reactions which take place under conventional conditions can be accelerated by ultrasonic cavitations. In general, the chemical effects of ultrasonic irradiation fall into three areas: homogeneous sonochemical effects of liquids, heterogeneous sonochemical effects of liquid-liquid or liquid-solid systems, and sonocatalytic effects. It has been proposed that liquid-liquid systems are used for the fabrication of nano-metal particles in the past. In this study, the fabrication of nano-metal particles and supported composites was investigated for the liquid-solid system from a viewpoint of economy and ecology. By choosing suitable conditions, it is reasonable to expect that these simple ultrasonic processes can be extended to obtain nano-sized metal particles. Thus applications by using these reactions were investigated to prepare the nano-sized metal particle supported materials, and mechanisms were investigated.

  120. Various applications of silver nano-particles by ultrasonic eco-fabrication 査読有り

    Hayashi, Y., Takizawa, H., Saijo, Y., Sekino, T., Suganuma, K., Niihara, K.

    Materials Science Forum 486-487 530-533 2005年

    出版者・発行元:Materials Science Forum

    DOI: 10.4028/0-87849-966-0.530  

    ISSN:1662-9752 0255-5476

    詳細を見る 詳細を閉じる

    Applications of silver nano-sized metal particles were investigated for a new, ecologically friendly and economical liquid-solid (silver oxide-alcohol) system. Silver metal oxides as starting materials have merits in metal particles fabrication because these materials are decomposed only by heating in air. That is, noble metal oxide does not use the strong reduction atmosphere. This reduction is ecologically clean because many noble metal oxides are not toxic, and because O-2 is evolved during decomposition. We reduced silver metal oxides by ultrasound and fabricated silver nano metal nanoparticles at room temperature, and various applications were investigated. By choosing a suitable process and conditions, it is reasonable to expect that ultrasonic eco-fabrications can be extended to obtain various silver nano-particles containing materials.

  121. Low-temperature growth of high-quality lead zirconate titanate thin films by 28 GHz microwave irradiation 査読有り

    Wang, Z.J., Kokawa, H., Takizawa, H., Ichiki, M., Maeda, R.

    Applied Physics Letters 86 (21) 212903-1-212903-3 2005年

    出版者・発行元:AMER INST PHYSICS

    DOI: 10.1063/1.1935748  

    ISSN:0003-6951

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    Pb(ZrxTi1-x)O-3 (PZT) thin films were coated on Pt/Ti/SiO2/Si substrates by a sol-gel method and then crystallized by 28 GHz microwave irradiation. The elevated temperature generated by microwave irradiation to obtain the perovskite phase is only 480 &DEG; C, which is significantly lower than that of conventional thermal processing. X-ray diffraction analysis indicated that the PZT films crystallized well in the perovskite phase. A scanning electron microscopy image showed that the film has a spherulite grain structure and most of the grains are approximately 2 &mu; m in size. The average values of the remanent polarization, coercive field, dielectric constant, and loss of the PZT films are 40 &mu; C/cm(2), 50 kV/cm, 1100, and 004, respectively. It is clear that microwave irradiation is effective for obtaining well-crystallized PZT films with good properties at low temperatures. &COPY; 2005 American Institute of Physics.

  122. Electrical properties and microstructures of sol-gel-deposited lead zirconate titanate thin films crystallized by 28 GHz microwave irradiation 査読有り

    Wang, Z.J., Kokawa, H., Takizawa, H., Ichiki, M., Maeda, R.

    Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers 44 (9 B) 6914-6917 2005年

    出版者・発行元:JAPAN SOC APPLIED PHYSICS

    DOI: 10.1143/JJAP.44.6914  

    ISSN:0021-4922 1347-4065

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    Pb(Zr(x)Ti(1-x))O(3) (PZT) thin films were coated on Pt/Ti/SiO(2)/Si substrates by a sol-gel method and then crystallized by 28 GHz microwave irradiation. The crystalline phases and microstructures as well as the electrical properties of the microwave-irradiated PZT films were investigated as a function of the elevated temperature generated by microwave irradiation. X-ray diffraction analysis indicated that the PZT films crystallized well into the perovskite phase at an elevated temperature of 480 degrees C by microwave irradiation. Scanning electron microscopy images showed that the films had a granular grain structure and most of the grains were approximately 1.5 mu m in size. With increasing elevated temperature from 480 degrees C to 600 degrees C by microwave irradiation, the breadth of grain boundaries of the films became narrow and the remanent polarization of the films increased slightly. It is clear that microwave irradiation is effective for obtaining well-crystallized PZT films with good properties at low temperatures in a short time.

  123. Ecodesigns and applications for noble metal nanoparticles by ultrasound process 招待有り 査読有り

    Hayashi, Y., Takizawa, H., Inoue, M., Niihara, K., Suganuma, K.

    IEEE Transactions on Electronics Packaging Manufacturing 28 (4) 338-343 2005年

    出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

    DOI: 10.1109/TEPM.2005.858452  

    ISSN:1521-334X

    詳細を見る 詳細を閉じる

    Ecodesigns for nano-sized noble metal particles were investigated by a new liquid-solid (metal oxide-alcohol) system. We have reduced noble metal oxides as low-emission starting materials by ultrasound and tried to fabricate various noble metal nanoparticles (Ag, An, Pt, Pd) at room temperature, Noble metal oxides were investigated during decomposition. These reductions are ecologically clean, because many noble metal oxides are not toxic, and during decomposition, O(2) is evolved. By choosing suitable conditions, it is reasonable to expect that this simple sonochemical process can be extended to obtain nano-sized metal particles.

  124. 金属ナノ粒子における低コスト・低環境負荷ファブリケーション

    林 大和, 滝澤博胤, 菅沼克昭, 新原晧一

    エコデザイン2004ジャパンシンポジウム論文集 304-307 2004年12月6日

  125. マイクロ波焼結による酸化チタン多孔質膜の接合 査読有り

    冨羽美帆, 内田 聡, 滝沢博胤

    セラミックス 39 (6) 435-438 2004年6月

    出版者・発行元:日本セラミックス協会

    ISSN:0009-031X

  126. Preparation of TiO<inf>2</inf> nanocrystalline electrode for dye-sensitized solar cells by 28 GHz microwave irradiation 査読有り

    Uchida, S., Tomiha, M., Masaki, N., Miyazawa, A., Takizawa, H.

    Solar Energy Materials and Solar Cells 81 (1) 135-139 2004年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/j.solmat.2003.08.020  

    ISSN:0927-0248

    詳細を見る 詳細を閉じる

    Microwave preparation of TiO2 nanocrystalline electrode for use in dye-sensitized solar cells is examined. A multi-mode microwave heating system operating at a frequency of 28 GHz is used to produce rapid processing. Well-sintered TiO2 nanocrystalline thin film is successfully fabricated on transparent conductive FTO glass electrode. Photoelectron energy conversion efficiency of 5.51% is achieved in an electrode prepared by 28 GHz microwave irradiation at 0.7 kW for 5 min. (C) 2003 Elsevier B.V. All rights reserved.

  127. Flexible dye-sensitized solar cells by 28 GHz microwave irradiation 査読有り

    Uchida, S., Tomiha, M., Takizawa, H., Kawaraya, M.

    Journal of Photochemistry and Photobiology A: Chemistry 164 (1-3) 93-96 2004年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/j.jphotochem.2004.01.026  

    ISSN:1010-6030

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    Microwave preparation of TiO2 nanocrystalline electrode for use in dye-sensitized solar cells is examined. A multi-mode microwave heating system operating at a frequency of 28 GHz is used to produce rapid synthesis. Well-sintered TiO2 nanocrystalline thin film is successfully fabricated on transparent conductive PET-ITO electrode. Photoelectron energy conversion efficiency of 2.16% is achieved in an electrode prepared by 28 GHz microwave irradiation at 1.0 kW for 5 min. (C) 2004 Elsevier B.V. All rights reserved.

  128. Transport properties of germanium-filled CoSb <inf>3</inf> 査読有り

    Nolas, G.S., Yang, J., Takizawa, H.

    Applied Physics Letters 84 (25) 5210-5212 2004年

    出版者・発行元:AMER INST PHYSICS

    DOI: 10.1063/1.1765205  

    ISSN:0003-6951

    eISSN:1077-3118

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    We report the transport properties of dense polycrystalline Ge filled skutterudites Ge0.25Co4Sb12 and Ge0.05Co4Sb12 perepared by a high-pressure synthesis approach. Low temperature electrical resistivity, Seebeck coefficient, Hall coefficient, and thermal conductivity measurements were performed and compared with those of Co4Sb11Ge and CoSb3. The Ge atoms residing inside the interstitial voids of the skutterudite crystal structure act as electron donors. The lattice thermal conductivity of these compounds is lower than that of CoSb3 but higher than that of other filled skutterudites. The potential for thermoelectric applications is also discussed. (C) 2004 American Institute of Physics.

  129. 28 GHzマイクロ波を利用したフィルム状色素増感太陽電池の作製

    冨羽美帆, 内田 聡, 滝沢博胤, 瓦家正英

    MATERIAL STAGE 3 (5) 47-51 2003年8月

  130. 28 GHzマイクロ波による酸化チタン膜の焼成と色素増感太陽電池への応用

    冨羽美帆, 内田 聡, 滝沢博胤

    機能材料 23 (6) 58-63 2003年6月

    出版者・発行元:シーエムシー出版

    ISSN:0286-4835

  131. High Pressure Synthesis of Advanced Inorganic Materials 査読有り

    H. Takizawa

    Proceedings of The 10th International Symposium on Advanced Materials 37-38 2003年3月

  132. Mn<inf>3</inf>Sb: A new L1<inf>2</inf>-type intermetallic compound synthesized under high-pressure 査読有り

    Yamashita, T., Takizawa, H., Sasaki, T., Uheda, K., Endo, T.

    Journal of Alloys and Compounds 348 (1-2) 220-223 2003年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(02)00834-4  

    ISSN:0925-8388

    eISSN:1873-4669

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    A new intermetallic compound, Mn3Sb, has been synthesized by direct reaction of elemental components at 6.2 GPa and 1000 degreesC for 30 min using a belt-type high-pressure apparatus. The compound crystallizes into a cubic structure with the space group Pm-3m, namely the Ll(2)-type (Cu3Au-type) structure. The structure was refined by the Rietveld analysis of the powder X-ray diffraction data and the lattice constant was determined to be a = 0.40017(2) nm. The compound exhibits metallic conductivity and weak ferromagnetism. (C) 2002 Elsevier Science B.V. All rights reserved.

  133. High-pressure synthesis of a new calcium thioborate, CaB<inf>2</inf>S<inf>4</inf> 査読有り

    Sasaki, T., Takizawa, H., Takeda, T., Endo, T.

    Materials Research Bulletin 38 (1) 33-39 2003年

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/S0025-5408(02)01005-X  

    ISSN:0025-5408

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    A new calcium thioborate, CaB2S4, was synthesized at high-pressure/temperature condition of 6.2 GPa and 800-1100 degreesC. The crystal structure was refined by the Rietveld method using powder X-ray diffraction data. The compound crystallizes into a cubic unit cell (a = 11.210 Angstrom, space group: M), isostructural with a high-pressure polymorph of calcium borate, CaB2O4-IV. The unit cell consists of three-dimensional linkage of BS4-tetrahedra, and calcium atoms have coordination number of 12. (C) 2002 Elsevier Science Ltd. All rights reserved.

  134. Synthesis, crystal structure refinement, electrical and magnetic properties of BaV<inf>13</inf>O<inf>18</inf> and SrV<inf>13</inf>O<inf>18</inf> 査読有り

    Iwasaki, K., Takizawa, H., Yamane, H., Kubota, S., Takahashi, J., Uheda, K., Endo, T.

    Materials Research Bulletin 38 (1) 141-148 2003年

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/S0025-5408(02)00978-9  

    ISSN:0025-5408

    eISSN:1873-4227

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    Polycrystalline samples of BaV13O18 and SrV13O18 were prepared by solid-state reaction of BaCO3, SrCO3, V2O5 and V at 1773-2073 K in flowing Ar. The crystal structures of BaV13O18 (R-3, a(h) = 12.6293(10) Angstrom, c(h) = 7.0121(4) Angstrom) and SrV13O18 (a(h) = 12.5491(7) Angstrom, c(h) = 6.9878(3) Angstrom) were refined by the Rietveld method using X-ray diffraction data. BaV13O18 exhibited semiconducting behavior with electrical resistivity from 5.8 x 10(-3) to 2.7 x 10(-3) Omega cm at 100-300 K. Electrical resistivity of SrV13O18 ranged from 1.5 x 10(-3) to 1.8 X 10(-3) Omega cm, and it increased slightly up to around 250 K and decreased above 250 K with increasing temperature. Negative Seebeck coefficients of both compounds at 100-300 K indicated that electron was the dominant carrier. BaV13O18 and SrV13O18 showed paramagnetism with the effective magnetic moment of 0.11mu(B) and 0.15mu(B), respectively, at 10-100 K. (C) 2002 Elsevier Science Ltd. All rights reserved.

  135. Polarized Raman-scattering study of Ge and Sn-filled CoSb <inf>3</inf> 査読有り

    Nolas, G.S., Kendziora, C.A., Takizawa, H.

    Journal of Applied Physics 94 (12) 7440-7444 2003年

    出版者・発行元:AMER INST PHYSICS

    DOI: 10.1063/1.1628377  

    ISSN:0021-8979

    eISSN:1089-7550

    詳細を見る 詳細を閉じる

    Raman-scattering spectra of Ge-filled and Sn-filled CoSb3 were studied as a function of polarization. Polarized Raman-scattering spectra of CoSb3 were used to help distinguish the symmetry of each vibrational mode observed in the filled skutterudite specimens. Seven out of the eight Raman-active Sb vibrational modes of CoSb3 and the Ge-filled skutterudites were identified for each specimen. We also compare our experimental assignments with theoretical calculations for CoSb3. The Sn atoms "rattle" inside the voids of the crystal structure and interact strongly with the lattice vibrations to shift and broaden the Sb-vibrational modes as compared to the spectra of CoSb3. The smaller and lighter Ge atoms however do not have such an effect on the lattice vibrations, indicating that the interaction of Ge with the lattice is relatively weak in comparison. (C) 2003 American Institute of Physics.

  136. Millimeter-Wave Processing of LaCrO<inf>3</inf> and LaNiO<inf>3</inf> Perovskites Using 28 GHz Frequency 査読有り

    Takizawa, H., Iwasaki, M.

    IEICE Transactions on Electronics E86-C (12) 2469-2473 2003年

    出版者・発行元:IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG

    ISSN:0916-8524

    eISSN:1745-1353

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    wBoth Cr2O3 and NiO absorb 28 GHz millimeter-wave energy well and this strong coupling with millimeter-waves can be used to promote a chemical reaction with La2O3 to form perovskite-type LaCrO3 or LaNiO3 ceramics. In La2O3-Cr2O3 system, the reaction proceeded rapidly and single phase LaCrO3 could be synthesized within 15 min even at lower temperature (similar to400degreesC) as compared to conventional synthesis (T &gt; 800degreesC). In the case of LaNiO3, the reaction proceeded rapidly in the early stage of heating (t &lt; 15 min), but not completed even after prolonged millimeter-wave irradiation. The results suggest an importance of millimeter-wave penetration depth, especially for processing of conductive materials.

  137. Microwave Processing of Inorganic Materials Using 28 GHz Frequency 査読有り

    Hirotsugu Takizawa

    Proceedings of International Symposium on Innovative Materials Processing by Controlling Chemical Reaction Field (IMP2002) 69-72 2002年11月

  138. Synthesis of Inorganic Materials by 28 GHz Microwave Irradiation 査読有り

    Hirotsugu Takizawa, Masato Iwasaki, Teiichi Kimura, Atsushi Fujiwara, Naoto Haze, Tadashi Endo

    Transactions of the Materials Research Society of Japan 27 (1) 51-54 2002年4月

  139. L1<SUB>2</SUB>型構造を有する新規強磁性金属間化合物Mn<SUB>3</SUB>Geの合成 査読有り

    滝沢博胤, 山下貴弘, 佐々木 剛, 上田恭太, 遠藤 忠

    粉体および粉末冶金 49 (1) 47-51 2002年

    出版者・発行元:None

    DOI: 10.2497/jjspm.49.47  

    ISSN:0532-8799

  140. Microwave synthesis of Fe-doped β-rhombohedral boron 査読有り

    Hirotsugu Takizawa, Naoto Haze, Keisuke Okamoto, Kyota Uheda, Tadashi Endo

    Materials Research Bulletin 37 (1) 113-121 2002年

    出版者・発行元:None

    DOI: 10.1016/S0025-5408(01)00803-0  

    ISSN:0025-5408

    eISSN:1873-4227

  141. Synthesis and crystal structure of Na<inf>4</inf>Sn<inf>3</inf>O<inf>8</inf> 査読有り

    Iwasaki, M., Takizawa, H., Uheda, K., Endo, T.

    Journal of Materials Chemistry 12 (4) 1068-1070 2002年

    出版者・発行元:ROYAL SOC CHEMISTRY

    DOI: 10.1039/b107364h  

    ISSN:0959-9428

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    A new ternary Na-Sn-O compound, Na4Sn3O8, has been synthesized from a mixture of Na2CO3 and SnO2 by heating at 1270-1400 degreesC for 6-24 h in air using a powder bed. The crystal structure of Na4Sn3O8 has been refined by the Rietveld analysis of the powder X-ray diffraction data. Na4Sn3O8 crystallizes in the cubic system (a = 9.1815(2) Angstrom, Z = 4) with the space group of either P4(3)32 or P4(1)32. The unit cell contains twelve SnO6 and four NaO6 octahedra connecting by edge-sharing and additionally twelve sodium atoms distributed in octahedral holes.

  142. Synthesis, crystal structure and electrical properties of Ba<inf>2</inf>Nb<inf>5-x</inf>V<inf>x</inf>O<inf>9</inf> (x&lt;1.9) 査読有り

    Iwasaki, K., Yamane, H., Kubota, S., Takahashi, J., Shimada, M., Takizawa, H., Uheda, K., Endo, T.

    Journal of Alloys and Compounds 339 (1-2) 268-274 2002年

    DOI: 10.1016/S0925-8388(01)02008-4  

    ISSN:0925-8388

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    The Ba2Nb5-xVxO9 solid solution was synthesized by replacement of Nb by V in Ba2Nb5O9. The polycrystalline samples were prepared by solid state reaction at 1773 K under flowing Ar. Ba2Nb5O9 has three Nb sites the Nb(1) and Nb(2) sites form the Nb6 octahedron, and the Nb(3) site is in the center of the NbO6 octahedron. The Rietveld analysis indicated that V atoms occupied both Nb(1) and Nb(2) sites. The a and c axis lengths decreased with increasing V content (a=4.171-4.106 Å, c=12.224-12.136 Å), the substitution range was estimated to be 0≤x&lt 1.9. The electrical resistivity of Ba2Nb5-xVxO9 showed metallic behavior at 100-350 K, which increased with increasing V content. Substitution of V atoms changed the main conductive carrier the Seebeck coefficient of Ba2Nb5-xVxO9 increased with increasing V content and it exhibited positive value at x=1.5 in 100-300 K while the Seebeck coefficient of Ba2Nb5O9 (x=0) showed a negative value. © 2002 Elsevier Science B.V. All rights reserved.

  143. High-pressure synthesis and crystal structure of B<inf>2</inf>S<inf>3</inf> 査読有り

    Sasaki, T., Takizawa, H., Uheda, K., Yamashita, T., Endo, T.

    Journal of Solid State Chemistry 166 (1) 164-170 2002年

    出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE

    DOI: 10.1006/jssc.2002.9575  

    ISSN:0022-4596

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    Two new high-pressure phases of binary boron-sulfur compounds, B2S3-II and B2S3-III, were synthesized at 3-6.2 GPa. A single crystal of B2S3-III was grown and the structure was determined (tetragonal, space group I4(1)/a, a = 16.086(2),Angstrom, c = 30.488(4)Angstrom; V = 7888(l) Angstrom(3), Z = 100, R = 3.0% and R-w = 2.8% for 3047 observed data [I &gt; 3.00sigma (I)]. The structure of B2S3-III consists of two kinds of macrotetrahedra built up from 20 and 34 BS4-tetrahedra. These macrotetrahedra connect each other to form an interpenetrating zincblende-type structure by sharing BS4-tetrahedra at the corners of those. B2S3-III is anticipated having a rather disordered structure. From the UV-Vis diffuse reflectance spectrum, the optical band gap of B2S3-III was estimated to be 3.7 eV. (C) 2002 Elsevier Science (USA).

  144. Crystal structure and luminescence properties of Sr<inf>2</inf>Al<inf>6</inf>O<inf>11</inf>:Eu<sup>2+</sup> 査読有り

    Takeda, T., Takahashi, K., Uheda, K., Takizawa, H., Endo, T.

    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 49 (12) 1128-1133 2002年

    出版者・発行元:Funtai Funamtsu Yakin Kyokai/Japan Soc. of Powder Metallurgy

    DOI: 10.2497/jjspm.49.1128  

    ISSN:0532-8799

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    Eu2+ activated Sr2Al6O11 and Sr4Al14O25 were prepared with B2O3 additives at the temperatures of 1100°C to 1300°C in flowing 5% H2/Ar gas. These products were characterized by XRD analysis, UV and VUV spectroscopy and so forth. The precise crystal structure of Sr2Al6O11 was first determined by Rietveld method. Between the sheets of the edge shared AlO6 octahedron, the corner shared AlO4 tetrahedral linkages of Sr2Al6O11 demonstrated a quite different fashion than that of Sr4Al14O25. According to the UV-Vis. and VUV spectra, an intense broad emission was observed near 460 nm in Sr2Al6O11:Eu2+, and two emission peaks were recognized at 409 nm and 496 nm in Sr4Al14O25:Eu2+. It was found that such emission profile and the thermal degradation of luminescence were fairly sensitive to every structural characteristic.

  145. Microwave processing of advanced ceramics using 28 GHz frequency 査読有り

    H Takizawa, T Kimura, M Iwasaki, K Uheda, T Endo

    IMPROVED CERAMICS THROUGH NEW MEASUREMENTS, PROCESSING, AND STANDARDS 133 211-216 2002年

    出版者・発行元:AMER CERAMIC SOC

    ISSN:1042-1122

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    Microwave heating behavior of various ceramic components was studied using a multi-mode microwave heating equipment operating at a frequency of 28 GHz. Many transition metal oxides and some semiconducting p-block oxides strongly absorb 28 GHz microwaves. These materials can be heated rapidly under microwave irradiation and the resultant heat can be used to drive a chemical reaction with other components. Examples of the synthesis of various complex oxides by 28 GHz microwave irradiation are given. The process sometimes brings unexpected products as a result of microwave-material interaction.

  146. High-pressure synthesis of ferromagnetic Mn<inf>3</inf>Ge with the Cu<inf>3</inf>Au-type structure 査読有り

    Takizawa, H., Yamashita, T., Uheda, K., Endo, T.

    Journal of Physics Condensed Matter 14 (44 SPEC ISS.) 11147-11150 2002年

    出版者・発行元:IOP PUBLISHING LTD

    DOI: 10.1088/0953-8984/14/44/442  

    ISSN:0953-8984

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    A new intermetallic compound. Mn3Ge, has been synthesized by direct reaction of elemental components at 6.2 GPa and 1000degreesC for 30 min using a belt-type high-pressure apparatus. The compound crystallizes into a cubic structure with the space group Pm3m, namely the L1(2)-type (Cu3Au-type) structure. The structure was refined by Rietveld analysis of the powder x-ray diffraction data and the lattice constant was determined as a = 0.380 19(3) nm. The compound shows metallic conductivity and ferromagnetism with a Curie temperature of 400 K.

  147. 層状化合物A<SUB>n</SUB>Nb<SUB>n+3m</SUB>O<SUB>3n+3m</SUB>[(ANbO<SUB>3</SUB>)<SUB>n</SUB>(NbO)<SUB>3m</SUB>](A=Ba, Sr)の形成に及ぼすANbO<SUB>3</SUB>(ペロブスカイト型)ブロックの格子サイズ・対称性の影響 査読有り

    岩崎航太, 滝沢博胤, 上田恭太, 山根久典, 島田昌彦, 遠藤 忠

    日本セラミックス協会学術論文誌 109 (12) 1023-1027 2001年12月

    出版者・発行元:None

    DOI: 10.2109/jcersj.109.1276_1023  

    ISSN:1882-0743

    eISSN:1348-6535

  148. Microwave Processing of Indium Double Oxides 査読有り

    M. Iwasaki, H. Takizawa, K. Uheda, T. Endo

    Proceedings of 2000 Powder Metallurgy World Congress (1) 749-751 2001年6月

  149. Synthesis and Physical Properties of Ba-Sr-V-O Compounds Containing Low Valence State Vanadium Ions 査読有り

    K. Iwasaki, H. Takizawa, K. Uheda, T. Endo

    Proceedings of 2000 Powder Metallurgy World Congress (2) 1436-1438 2001年6月

  150. High pressure synthesis of binary B-S compounds 査読有り

    Sasaki, T., Takizawa, H., Uheda, K., Endo, T.

    Physica Status Solidi (B) Basic Research 223 (1) 29-33 2001年

    出版者・発行元:WILEY-V C H VERLAG GMBH

    DOI: 10.1002/1521-3951(200101)223:1<29::AID-PSSB29>3.0.CO;2-O  

    ISSN:0370-1972

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    r-BS was synthesized under high pressure/temperature conditions. Rietveld analysis of the powder X-ray diffraction data was performed by applying the structure model of GaS 3R (space group: R3m) with the lattice parameters of a(hex) = 3.05223(7) Angstrom and c(hex) = 20.3119(5) Angstrom The crystal structure of r-BS was revealed to be the three-layer structure comprised of the units built up from B-B pairs which art: inside the anti-prism of S atoms. The measurement of UV-Vis diffused reflectance spectrum showed that the estimated band gap of r-BS was about 3.4 eV, and the coloring of r-BS was observed as broad absorption at 510 nm.

  151. High pressure crystal chemistry of transition metal diantimonides 査読有り

    Takizawa, H., Yamashita, T., Uheda, K., Endo, T.

    Physica Status Solidi (B) Basic Research 223 (1) 35-39 2001年

    出版者・発行元:WILEY-V C H VERLAG GMBH

    DOI: 10.1002/1521-3951(200101)223:1<35::AID-PSSB35>3.0.CO;2-9  

    ISSN:0370-1972

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    High-pressure crystal chemistry of transition metal diantimonides is discussed. Two types of pressure-induced phase transitions, marcasite-type to CuAl2-type and marcasite-type to pararammels-bergite-type, occur in this family The former is found in CrSb2 and the transition is accompanied by a change in bonding character from the mixed ionic and covalent to metallic. The latter is found in NiSb2 and can be explained by effective packing of NiSb6 octahedra. The local environment of nickel atom remains unchanged during the transition. The phase transition sequences in transition metal diantimonides, together with other dipnictides and dichalcogenides, are schematically summarized.

  152. GdBO<inf>3</inf>:Eu phosphor particles with uniform size, plate morphology, and non-aggregation 査読有り

    Wang, Y., Uheda, K., Takizawa, H., Endo, T.

    Chemistry Letters (3) 206-207 2001年

    出版者・発行元:CHEMICAL SOC JAPAN

    DOI: 10.1246/cl.2001.206  

    ISSN:0366-7022

    eISSN:1348-0715

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    GdBO3:Eu vaterite type particles with fine size, plate morphology, and non-aggregation were first prepared by the mild hydrothermal method. Their characteristics were investigated and compared with those of particles prepared by solid state reactions. The result showed that the hydrothermal method appears to be applicable to prepare high quality phosphors for practical uses. This conclusion was reinforced by the existence of an important improvement in the photoluminescent performances.

  153. Weak ferromagnetism of bixbyite-type (In<inf>0.67</inf>Fe<inf>0.33</inf>)<inf>2</inf>O<inf>3</inf> synthesized by 28 GHz microwave irradiation 査読有り

    Takizawa, H., Uheda, K., Endo, T.

    Journal of Materials Science Letters 20 (4) 359-361 2001年

    出版者・発行元:KLUWER ACADEMIC PUBL

    DOI: 10.1023/A:1006710408736  

    ISSN:0261-8028

  154. ホーランダイト型構造をもつ新規化合物,K<SUB>x</SUB>Ca<SUB>x/2</SUB>Sn<SUB>8-x/2</SUB>O<SUB>16</SUB> (x≦2)の合成と電気的性質 査読有り

    本多 充, 佐久間 純, 上田恭太, 滝沢博胤, 遠藤 忠, 島田昌彦

    粉体および粉末冶金 48 (3) 251-253 2001年

    出版者・発行元:None

    DOI: 10.2497/jjspm.48.251  

    ISSN:0532-8799

  155. Microwave synthesis of yttrium aluminium iron garnet powder 査読有り

    Kimura, T., Takizawa, H., Uheda, K., Endo, T., Shimada, M.

    Journal of Materials Synthesis and Processing 9 (2) 57-61 2001年

    出版者・発行元:CONSULTANTS BUREAU

    DOI: 10.1023/A:1011304323858  

    ISSN:1064-7562

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    The solid solution of yttrium aluminum gamet-yttrium iron garnet [YAIG, Y-3(Al,Fe)(5)O-12] was synthesized from the component oxides by 28 GHz-microwave irradiation. The compositions of the resulting garnets were not the same as the nominal compositions. This difference could be explained by selective coupling of chemical species with microwaves, predictable from the temperature-time profiles of each raw material under microwave irradiation. The diffusion process under microwave irradiation was discussed.

  156. Crystal structure of BaV<inf>13</inf>O<inf>18</inf> 査読有り

    Iwasaki, K., Takizawa, H., Uheda, K., Endo, T., Shimada, M.

    Journal of Solid State Chemistry 158 (1) 61-67 2001年

    出版者・発行元:ACADEMIC PRESS INC

    DOI: 10.1006/jssc.2000.9058  

    ISSN:0022-4596

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    Single crystals of BaV13O18 (V+2.62) containing a small amount of Cr (about 7% of vanadium sites) were prepared by heating a mixture of BaCO3, V2O5, V, and Cr powders at 1973 K for 40 h in flowing Ar. Crystal structure analysis using single-crystal data (Rigaku AFC7R, 4037 reflections) showed that the BaV13O18 has a rhombohedral unit cell with a(h) = 12.621(5) Angstrom, C-h = 7.020(5) Angstrom, v = 968.4(9) Angstrom (3), Z = 3, D-cal = 5.595 g.cm(-3) and space group R-3 (R-1 = 1.96%, wR(2) = 3.60%, S = 1.095), In the structure, Be and O formed a cubic close-packed arrangement and every V was coordinated by six O, BaV13O18 has three kinds of vanadium environments: one almost regular octahedral site and two distorted octahedral sites. VO6 octahedra share their corners and edges, (C) 2001 Academic Press.

  157. Synthesis of Gd<SUB>1-x</SUB>Eu<SUB>x</SUB>Al<SUB>3</SUB>(BO<SUB>3</SUB>)<SUB>4</SUB> (0<x≦1) and Its Photoluminescence Properties under UV and Vacuum Ultraviolet Regions 査読有り

    Yuhua Wang, Kyota Uheda, Hirotsugu Takizawa, Ushirozawa Mizumoto, Tadashi Endo

    Journal of the Electrochemical Society 148 (8) G430-G433 2001年

    出版者・発行元:None

    DOI: 10.1149/1.1383778  

    ISSN:0013-4651

  158. Photo- and thermo-luminescence of zinc silicon nitride doped with divalent manganese 査読有り

    Uheda, K., Takizawa, H., Endo, T., Miura, C., Shimomura, Y., Kijima, N., Shimada, M.

    Journal of Materials Science Letters 20 (19) 1753-1755 2001年

    出版者・発行元:KLUWER ACADEMIC PUBL

    DOI: 10.1023/A:1012563812625  

    ISSN:0261-8028

  159. High pressure synthesis of new filled skutterudites 招待有り 査読有り

    H Takizawa, K Okazaki, K Uheda, T Endo, GS Nolas

    THERMOELECTRIC MATERIALS 2001-RESEARCH AND APPLICATIONS 691 37-47 2001年

    出版者・発行元:MATERIALS RESEARCH SOC

    ISSN:0272-9172

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    Filled skutterudites exhibit properties that comply with the concept of a "phonon-glass electron-crystal", as proposed by Slack. The optimal filled skutterudite would have filler atoms that exhibit large thermal vibration amplitudes in the voids of the crystal structure. It is desirable that these loosely bound atoms give rise to strong phonon scattering without greatly affecting the essential part of the band structure of the skutterudites. This criterion is difficult to meet. Most attempts have employed charge compensation for filling fractions above 50 %. In this report we present the use of a high-pressure technique for the synthesis of new filled skutterudites. By using our high-pressure synthesis technique CoSb3-based skutterudites filled with group-14 elements (Ge, Sn, and Pb) have been synthesized with up to 100 % filling without charge compensation of the host lattice. The structural analysis reveals that the Sn atoms exhibit very large thermal vibration amplitude, indicative of a large "rattling" motion. The Sn-filled specimens exhibit a low thermal conductivity, lower than that of any previously reported filled skutterudite, while the favorable semiconducting nature of the host lattice is not substantially changed by Sn filling. Tin atoms may therefore be better "rattlers" in the CoSb3 host lattice than lanthanide or actinide atoms.

  160. Microwave synthesis of X-rays amorphous ferrites and the magnetic properties 査読有り

    T. Kimura, H. Takizawa, K. Uheda, T. Endo

    Proceedings of the Second International Conference on Microwave Chemistry 335-338 2000年10月

  161. スズを充填したスクッテルダイト型Sn_xCo_4Sb_<12>の合成と熱電特性

    滝沢 博胤, 伊藤 雅之, 上田 恭太, 遠藤 忠

    日本セラミックス協会学術論文誌 : Nippon Seramikkusu Kyokai gakujutsu ronbunshi 108 (1258) 530-534 2000年6月1日

    出版者・発行元:公益社団法人日本セラミックス協会

    DOI: 10.2109/jcersj.108.1258_530  

    ISSN:1882-1022

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    Tin atoms were inserted into the skutterudite-type CoSb_3 host lattice under high pressure and temperature conditions. It was found that Sn atoms could be inserted into the body-centered vacant site, resulting in the formation of new filled (or partially filled) skutterudites, Sn_xCo_4Sb_<12>. The degree of insertion (x) increases with increasing applied pressure, and the vacant sites of the CoSb_3 host lattice is fully occupied by Sn atoms when the reaction is carried out at 8 GPa and at 550℃. X-ray Rietveld refinement revealed that the inserted Sn atom showed an anomalously large isotropic atomic displacement parameter, indicating a large thermal vibration amplitude at the body-centered position. The Sn-filled skutterudites exhibit n-type semiconducting behaviour indicating that Sn filling causes the formation of a donor level.

  162. 28GHzマイクロ波照射による希土類含有複酸化物の合成

    滝沢博胤, 木村禎一, 岩崎将任, 上田恭太, 遠藤忠

    希土類 (36) 104-105 2000年5月16日

    ISSN:0910-2205

  163. Synthesis and luminescent property of Eu<sup>3+</sup>-doped LaSi<inf>3</inf>N<inf>5</inf> phosphor 査読有り

    Uheda, K., Takizawa, H., Endo, T., Yamane, H., Shimada, M., Wang, C.-M., Mitomo, M.

    Journal of Luminescence 87 967-969 2000年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/S0022-2313(99)00494-9  

    ISSN:0022-2313

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    By a solid state reaction of LaN, Eu2O3 and Si3N4, LaSi3N5, La0.9Eu0.1Si3 N5-XOX and LaEuSi2N3O2 were prepared at 1900 degrees C for 2h under 1.01 x 10(6) N m(-2) nitrogen pressure. These compounds were identified by X-ray diffraction analysis, and then characterized by means of absorption and luminescence spectroscopies. La0.9Eu0.1Si3N5-XOX was isostructural with LaSi3N5. For only La0.9Eu0.1Si3 N5-XOX, we observed a broad emission band with a maximum at 549 nm due to the 4f(6)5d --&gt; 4f(7) transition of Eu2+. On the other hand, the Eu2+ ion in LaEuSi2N3O2 showed a deep-red emission band at 650 nm. (C) 2000 Elsevier Science B.V. All rights reserved.

  164. Synthesis and thermoelectric properties of tin-filled skutterudite, Sn<inf>x</inf>Co<inf>4</inf>Sb<inf>12</inf> 査読有り

    Takizawa, H., Ito, M., Uheda, K., Endo, T.

    Journal of the Ceramic Society of Japan 108 (6) 530-534 2000年

    出版者・発行元:CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

    DOI: 10.2109/jcersj.108.1258_530  

    ISSN:0914-5400

    eISSN:1348-6535

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    Tin atoms were inserted into the skutterudite-type CoSb3 host lattice under high pressure and temperature conditions. It was found that Sn atoms could be inserted into the body-centered vacant site, resulting in the formation of new filled (or partially filled) skutterudites, SnxCo4Sb12. The degree of insertion (x) increases with increasing applied pressure, and the vacant sites of the CoSb3 host lattice is fully occupied by Sn atoms when the reaction is carried out at 8 GPa and at 550 degrees C, X-ray Rietveld refinement revealed that the inserted Sn atom showed an anomalously large isotropic atomic displacement parameter, indicating a large thermal vibration amplitude at the body-centered position, The Sn-filled skutterudites exhibit n-type semiconducting behaviour indicating that Sn filling causes the formation of a donor level.

  165. NiGe<inf>2</inf>: A new intermetallic compound synthesized under high-pressure 査読有り

    Takizawa, H., Uheda, K., Endo, T.

    Journal of Alloys and Compounds 305 (1-2) 306-310 2000年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(00)00733-7  

    ISSN:0925-8388

    eISSN:1873-4669

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    A new nickel germanide, NiGe2, was synthesized under high pressure and temperature condition and the crystal structure was solved by the Rietveld analysis of the powder X-ray diffraction data. Single phase NiGe2 was obtained from the stoichiometric mixture of elemental components by the reaction at 5.5 GPa and 700 degrees C. The compound crystallizes into orthorhombic structure with the space group Cmca, isostructural with CoGe2. Lattice parameters were determined to be a=10.830(5) Angstrom, b=5.763(3) Angstrom, c=5.762(3) Angstrom. The structure contains isolated Ni-Ni bonds dong the a-axis. The compound is a metallic conductor with a temperature independent susceptibility. (C) 2000 Elsevier Science S.A. All rights reserved.

  166. Thermoelectric properties of Sn-filled skutterudites 査読有り

    Nolas, G.S., Takizawa, H., Endo, T., Sellinschegg, H., Johnson, D.C.

    Applied Physics Letters 77 (1) 52-54 2000年

    出版者・発行元:AMER INST PHYSICS

    DOI: 10.1063/1.126874  

    ISSN:0003-6951

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    Thermal conductivity, resistivity, Seebeck coefficient, and structure measurements of CoSb3 with tin interstitially placed in the voids are reported. These tin-filled skutterudites were synthesized under high pressure and temperature conditions; they cannot be synthesized under "normal" synthesis approaches. The tin atoms exhibit very large atomic displacement parameters indicating a large "rattling" motion inside their atomic "cages." The disorder induced by the Sn atoms is a very good phonon scattering mechanism. The thermal conductivity of these compounds is very low with a temperature dependence that is atypical of simple solids. The tin-filled compounds exhibit n-type semiconducting behavior with relatively high Seebeck coefficients for compounds whose electronic properties have not been optimized. The potential for thermoelectric applications is discussed. (C) 2000 American Institute of Physics. [S0003-6951(00)02527-4].

  167. Crystallization of the oxalate-linked copper (II) coordination polymer by Langmuir-Blodgett technique 査読有り

    K. Uheda, H. Ito, H. Takizawa, T. Endo, M. Shimada

    Transactions of the Materials Research Society of Japan 25 449-452 2000年

  168. Synthesis and electrical properties of Ba<inf>2</inf>Nb<inf>5-x</inf>Zr<inf>x</inf>O<inf>9</inf> 査読有り

    Iwasaki, K., Takizawa, H., Uheda, K., Endo, T., Shimada, M.

    Journal of Alloys and Compounds 308 (1-2) 109-114 2000年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(00)00904-X  

    ISSN:0925-8388

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    The Ba2Nb5-xZrxO9 solid solution was first synthesized by the solid state reaction, and Zr proved to be substituted selectively for Nb in the preferred site of Ba2Nb5O9. The structure of Ba2Nb5-xZrxO9 consists of a NbO layer sandwiched by two Ba(Nb, Zr)O-3 perovskite blocks. The limit of Zr-substitution was estimated to be x=1.0, according to the change of c axis parameter against x. SEM observation showed that platy agglomerates preferred the orientation of the 00l plane, and the particle size was reduced by up to 1/10 on the addition of Zr. The solid solution showed a metallic conductivity with a temperature independent magnetic susceptibility. Substitution of Zr for Nb appeared to cause a change in electron density as a result of contraction of the Nb(2)O(3) distance, leading to the increase of electrical resistivity. (C) 2000 Elsevier Science S.A. All lights reserved.

  169. 28 GHzマイクロ波を照射した酸化スズの光学的性質 査読有り

    岩崎将任, 滝沢博胤, 上田恭太, 遠藤 忠

    粉体および粉末冶金 47 (9) 999-1003 2000年

    出版者・発行元:None

    DOI: 10.2497/jjspm.47.999  

    ISSN:0532-8799

  170. Rapid formation and growth of bixbyite-type (In<inf>0.67</inf>Fe<inf>0.33</inf>)<inf>2</inf>O<inf>3</inf> by 28 GHz microwave irradiation 査読有り

    Takizawa, H., Uheda, K., Endo, T.

    Journal of the American Ceramic Society 83 (9) 2321-2323 2000年

    出版者・発行元:AMER CERAMIC SOC

    DOI: 10.1111/j.1151-2916.2000.tb01555.x  

    ISSN:0002-7820

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    (In0.67Fe0.33)(2)O-3 with the bixbyite structure was synthesized via 28 GHz microwave irradiation, using multimode microwave heating equipment. Indium sesquioxide strongly absorbs 28 GHz microwaves, and this strong coupling with microwave energy can be used to drive a reaction with iron sesquioxide. A mixture of In2O3 and alpha-Fe2O3 powders (In:Fe ratio of 2:1) was irradiated with microwaves at a frequency of 28 GHz, The mixture was heated to 1400 degrees C during the microwave irradiation. The formation of a solid solution was completed within a minute, which indicated a drastic enhancement of the reaction rate. Scanning electron microscopy revealed remarkable grain growth under microwave irradiation.

  171. Sn<SUB>x</SUB>Co<SUB>4</SUB>Sb<SUB>12</SUB>スクッテルダイトの熱電特性に及ぼすスズ原子挿入の効果 査読有り

    滝沢博胤, 伊藤雅之, 上田恭太, 遠藤 忠

    粉体および粉末冶金 47 (11) 1170-1174 2000年

    出版者・発行元:None

    DOI: 10.2497/jjspm.47.1170  

    ISSN:0532-8799

  172. Synthesis of Ba-V-O new compound containing low valence state vanadium ions 査読有り

    K. Iwasaki, H. Takizawa, K. Uheda, T. Endo, M. Shimada

    Transactions of the Materials Research Society of Japan 25 1163-1166 2000年

  173. Microwave synthesis and the electrical properties of Na<inf>x</inf>Co<inf>1-y</inf>Mn<inf>y</inf>O<inf>2</inf> 査読有り

    Iwasaki, M., Takizawa, H., Uheda, K., Endo, T.

    Journal of Materials Science Letters 19 (22) 2033-2035 2000年

    出版者・発行元:KLUWER ACADEMIC PUBL

    DOI: 10.1023/A:1026727406053  

    ISSN:0261-8028

  174. New high-pressure polymorph of NiSb<inf>2</inf> 査読有り

    Takizawa, H., Uheda, K., Endo, T.

    Intermetallics 8 (12) 1399-1403 2000年

    出版者・発行元:ELSEVIER SCI LTD

    DOI: 10.1016/S0966-9795(00)00091-1  

    ISSN:0966-9795

    eISSN:1879-0216

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    A new polymorph of NiSb2 was obtained under high-pressure/temperature condition of 6 GPa and 550-650 degreesC. The crystal structure is orthorhombic with the space group Phca (No. 61). isostructural with the low-temperature form of NiAs2 (pararammelsbergite). The crystallographic parameters were refined by the Rietveld analysis of the powder X-ray diffraction data (a = 0.62866(2) nm, b-0.63643(2) nm, c = 1.23670(3) nm, Z = 8). The structure can be regarded as an intermediate structure between the marcasite-type and the pyrite-type. The pararammelsbergite-type NiSb2 is a high-pressure form of NiSb2 and the density is slightly higher than that of ambient pressure form with the marcasite-type structure. (C) 2000 Elsevier Science Ltd. All rights reserved.

  175. ペロブスカイト型酸化物Sr_2(Sr_<1-x>M_x)TaO_z(M=Ca, Nd)の合成と格子歪み

    加藤 純雄, 阿部 剛士, 菅井 幹夫, 滝沢 博胤, 遠藤 忠

    日本セラミックス協会学術論文誌 : Nippon Seramikkusu Kyokai gakujutsu ronbunshi 107 (1247) 633-638 1999年7月1日

    出版者・発行元:公益社団法人日本セラミックス協会

    DOI: 10.2109/jcersj.107.633  

    ISSN:1882-1022

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    The perovskite-type solid solutions Sr_2(Sr_<1-x>M_x)TaO_z(M=Ca, Nd) were synthesized. Lattice distortion and cation ordering in the octahedral site of the perovskite type structure were investigated using Rietveld analysis of powder X-ray diffraction data. Cubic perovskite-type phases with cation ordering in octahedral site were obtained for Sr_2(Sr_<1-x>Ca_x)TaO_<5.5> (x=0-1), and Sr_2(Sr_<0.9>Nd_<0.1>)TaO_<5.55>. Two types of monoclinic perovskite-type phases were obtained for Sr_2(Sr_<1-x>Nd_x)TaO_z. The unit cell of the solid solutions for x=0.3-0.7 was close to a tetragonal cell. The distortion of the solid solutions was due to tilting octahedra and a difference in the direction of tilt was observed between the compounds for x=0.3-0.7 and x=0.9-1.0. Degree of monoclinic distortion increased with increasing Nd^<3+> content. Cation ordering in the octahedral sites was observed in all the compositions investigated for Sr_2(Sr_<1-x>Nd_x)TaO_z. Increase of Nd^<3+> content possibly causes increase of oxygen content z. The present results suggest that increase of oxygen content is one of the reasons to cause the lattice distortion for Sr_2(Sr_<1-x>M_x)TaO_z(M=Ca, Nd).

  176. バデライト型構造をもつMO<SUB>2</SUB>(M=Zr,Hf)の合成及び発光特性 査読有り

    清水孝之, 上田恭太, 滝沢博胤, 遠藤 忠, 島田昌彦

    粉体および粉末冶金 46 (2) 175-179 1999年

    出版者・発行元:None

    DOI: 10.2497/jjspm.46.175  

    ISSN:0532-8799

  177. マイクロ波照射による金属窒化物の合成 査読有り

    木村禎一, 滝沢博胤, 上田恭太, 遠藤 忠

    紛体および粉末冶金協会 46 (4) 378-382 1999年

    DOI: 10.2497/jjspm.46.378  

    ISSN:0532-8799

  178. Cation ordering in the oxygen deficient perovskite Sr<inf>2-x</inf>La<inf>x</inf>Mg<inf>1-y</inf>Ta<inf>1+y</inf>O<inf>z</inf> 査読有り

    Kato, S., Ohmori, E., Suzuki, Y., Ohshima, Y., Sugai, M., Takizawa, H., Endo, T.

    Journal of the Ceramic Society of Japan 107 (3) 209-214 1999年

    出版者・発行元:CERAMIC SOC JAPAN-NIPPON SERAMIKKUSU KYOKAI

    DOI: 10.2109/jcersj.107.209  

    ISSN:0914-5400

    eISSN:1348-6535

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    Perovskite-type solid solutions, Sr2-xLaxMg1-yTa1+yOz, were synthesized and cation ordering between Mg2+ and Ta5+ in the solid solutions was investigated. In the Sr2-xLaxMgTaOz system, the (NH4)(3)FeF6-type (1:1 order) phase was formed in the compositional range, x greater than or equal to 0.4. However, few degree of the cation ordering between Mg2+ and Ta5+ was also observed in the solid solutions, 0 less than or equal to x less than or equal to 0.3. These results suggest that the cation ordering between Mg2+ and Ta5+ in Sr2-xLaxMgTaOz system is affected by the average charge of A-site cation or, in other words, by the oxygen content. The 1 : a-type ordering was observed in the Sr2-xLax Mg1-yTa1+yOz solid solutions, x = 0 for y greater or equal to 0.3, and x less than or equal to 0.1 for y = 0.1, 0.2. In particular, the disappearance of the 1:2 ordering due to small amount of La3+ substitution was observed in the stoichiometric Sr2Mg0.67 Ta1.33O6-LaSrMgTaO6 solid solution. However, in the case of the composition containing oxygen vacancy, the 1 : 2 ordered phase was formed at the composition Mg/Ta = 0.8/1.2 and 0.9/1.1, although they have 20% and 35% higher Mg2+ content than in the case of Mg/Ta = 1/2, respectively. These results suggest that the 1:2 ordered structure is stabilized by the presence of oxygen vacancy.

  179. Synthesis of a new birnessite-type compound in K-Mg-Sn-O system 査読有り

    Uheda, K., Sakuma, J., Takeuchi, Y., Takizawa, H., Endo, T., Horiuchi, A., Shimada, M.

    Journal of Materials Science Letters 18 (5) 377-379 1999年

    出版者・発行元:KLUWER ACADEMIC PUBL

    DOI: 10.1023/A:1006676516299  

    ISSN:0261-8028

  180. Cation ordering in the perovskite-type Sr<inf>2-x</inf>La<inf>x</inf>Co<inf>1-y</inf>Ta<inf>1+y</inf>O<inf>6</inf> 査読有り

    Kato, S., Kawase, T., Ohshima, Y., Sugai, M., Takizawa, H., Endo, T.

    Journal of Alloys and Compounds 285 (1-2 Complete) 64-68 1999年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(99)00004-3  

    ISSN:0925-8388

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    Perovskite-related solid solutions, Sr2-xLaxCu1-yTa1+vOz, were synthesized by solid-state reaction at 1200 degrees C in air. The crystalline phases were identified by powder X-ray diffraction. The perovskite-type solid solutions with different ordering types were observed including simple cubic perovskite-type (random), the Ba(Sr1/3Ta2/3)O-3-type (1:2 ordering) and the (NH4)(3)FeF6-type (1:1 ordering). The 1:2 ordering phase formed near the Sr-2(Co0.67Ta1.33)O-6 composition. In the composition range, 0 less than or equal to y less than or equal to 0.2, the random and the 1:1 ordered phases formed. In the higher La3+ content region, the 1:1 ordering phase was observed. The valency state of Co decreased with increasing La3+ content and the perovskite cell expanded resulting from the increase of the average ionic radii on (Co,Ta) site. The 1:1 ordering of the ions on the octahedral site was found to be affected by the size difference of the ions more than the charge difference in this system. (C) 1999 Elsevier Science S.A. All rights reserved.

  181. Distortion and cation ordering in LaSr(Ni<inf>1-x</inf>Cu<inf>x</inf>)TaO<inf>6</inf> 査読有り

    Kato, S., Kawase, T., Ohshima, Y., Sugai, M., Takizawa, H., Endo, T.

    Journal of Alloys and Compounds 285 (1-2 Complete) 69-72 1999年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(99)00005-5  

    ISSN:0925-8388

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    The perovskite-type solid solution LaSr(Ni1-xCux)TaO6 was synthesized and characterized by powder X-ray diffraction and iodometric titration. The stoichiometric solid solutions were synthesized at 1050-1100 degrees C in air. The compounds for 0 less than or equal to x less than or equal to 0.6 have the (NH4)(3)FeF6-type structure with ordering between (Ni2+, Cu2+) and Ta5+. Tetragonal distorted (NH4)(3)FeF6-type phases due to the Jahn-Teller effect formed in the compositional range, x greater than or equal to 0.7 and the monoclinic distortion was observed for x=0.9 and 1.0. This result suggests that the tetragonal distortion occurs when the amount of Cu2+ becomes more than 35% of the octahedral site in this system. (C) 1999 Elsevier Science S.A. All rights reserved.

  182. New ferromagnetic polymorph of CrSb<inf>2</inf> synthesized under high pressure 査読有り

    Takizawa, H., Uheda, K., Endo, T.

    Journal of Alloys and Compounds 287 (1-2) 145-149 1999年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(99)00056-0  

    ISSN:0925-8388

    eISSN:1873-4669

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    A new ferromagnetic polymorph of CrSb2 was synthesized under high-pressure-temperature conditions. The crystal structure is body-centered tetragonal with the space group 14/mcm, namely the CuAl2-type structure. The experiments under various pressure conditions revealed that the high-pressure polymorph was formed above 5.5 GPa, and the compound crystallized into the low-pressure marcasite-type structure below 5 Gpa. The characteristic of the high-pressure phase is the metallic bond nature including the formation of Cr-Cr-Cr linear chain along the c-axis. The compound shows metallic conductivity and itinerant-electron ferromagnetic behavior with the Curie temperature of 160 K. (C) 1999 Elsevier Science S.A. All rights reserved.

  183. ペロブスカイト型酸化物Sr<SUB>2</SUB>(Sr<SUB>1-x</SUB>M<SUB>x</SUB>)TaO<SUB>z</SUB> (M=Ca, Nd)の合成と格子歪み 査読有り

    加藤純雄, 阿部剛士, 菅井幹夫, 滝沢博胤, 遠藤 忠

    日本セラミックス協会学術論文誌 107 (7) 633-638 1999年

    出版者・発行元:None

    DOI: 10.2109/jcersj.107.633  

    ISSN:0914-5400

    eISSN:1348-6535

  184. Synthesis and crystal structure of novel hollandite compounds A<inf>x</inf>Mg<inf>x/2</inf>Sn<inf>8-x/2</inf>O<inf>16</inf> (A = K, Rb, and Cs) 査読有り

    Uheda, K., Horiuchi, A., Takizawa, H., Endo, T.

    Journal of Porous Materials 6 (2) 161-166 1999年

    出版者・発行元:KLUWER ACADEMIC PUBL

    DOI: 10.1023/A:1009639607457  

    ISSN:1380-2224

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    We have prepared novel hollandite compounds A(x)Mg(x)/2Sn8-x/2O16 (A = K, Rb, and Cs) by solid state reaction, using A(2)CO(3) (A = K, Rb, and Cs), Mg(NO3)(2). 6H(2)O and SnO2 in the molar ratio 1 : 1 : 3, at 1500 degrees C for 5 hours in air. All compounds crystallize in the monoclinic space group C2/m. Their crystal structures and compositions were determined by the Rietveld analysis using X-ray powder diffraction data. K2MgSn7O16: a = 14.837(3) Angstrom, b = 3.1667(1) Angstrom, c = 10.490(2) Angstrom, beta = 134.919(8) Angstrom, and Z = 1, R-I = 7.32%. Rb2MgSn7O16: a = 14.890(4) Angstrom, b = 3.1706(1) Angstrom, c = 10.514(3) Angstrom, beta = 134.989(13) Angstrom, and Z = 1, R-B = 8.97%. Cs1.26Mg0.63Sn7.37O16: a = 15.015(3) Angstrom, b = 3.1656(1) Angstrom, c = 10.621(3) Angstrom, beta = 135.061(11) Angstrom, and Z = 1, R-I = 9.24%. Sn and Mg octahedra form the hollandite framework, and alkali ions are located in the hollandite tunnels. The Cs ion only partially occupies the tunnel, because the length of b-axis is shorter than Cs ion size. As a result, Cs hollandite only has the non-stoichiometric composition.

  185. CoSb<SUB>3</SUB>系フィルドスクッテルダイトの高圧合成と結晶構造精密化 査読有り

    滝沢博胤, 伊藤雅之, 上田恭太, 遠藤 忠

    粉体および粉末冶金 46 (10) 1113-1117 1999年

    出版者・発行元:None

    DOI: 10.2497/jjspm.46.1113  

    ISSN:0532-8799

  186. Production of phosphor (YAG : Tb) fine particles by hydrothermal synthesis in supercritical water 査読有り

    Hakuta, Y., Scino, K., Ura, H., Adschiri, T., Takizawa, H., Aral, K.

    Journal of Materials Chemistry 9 (10) 2671-2674 1999年

    出版者・発行元:ROYAL SOC CHEMISTRY

    DOI: 10.1039/a903074c  

    ISSN:0959-9428

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    Rapid and continuous production of phosphor (YAG: Tb) fine particles by hydrothermal synthesis in supercritical water was studied. At temperatures higher than the critical temperature of water, continuous and rapid (&lt;60 s) production of YAG: Tb fine particles was achieved. Emission spectra obtained by UV excitation of the particles were in agreement with the typical spectral pattern of YAG: Tb. Single phase YAG: Tb was produced by using stoichiometric mixtures of metal salts [Al(NO3)(3), Y(NO3)(3), and TbCl3] as aqueous solutions with an alkali molar ratio {[OH-]/([NO3-]+[Cl-])} of 1 and a rapid heating method. No additional thermal treatment was necessary to obtain crystalline products.

  187. Fabrication and photochromism of Langmuir-Blodgett films composed of polyoxometalate anions and n-alkylamines 査読有り

    K. Uheda, K. Ohno, H. Takizawa, T. Endo, M. Shimada

    Transactions of the Materials Research Society of Japan 24 457-460 1999年

  188. Synthesis of aluminium nitride using urea-precursors 査読有り

    Uheda, K., Takahashi, M., Takizawa, H., Endo, T., Shimada, M.

    Key Engineering Materials 159-160 53-58 1999年

    出版者・発行元:Key Engineering Materials

    ISSN:1662-9795 1013-9826

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    We synthesized ALN using aluminium chloride hexahydrate and urea as the starting materials. By directly introducing aluminium chloride into melted urea at 135 degrees C, a urea-precursor was formed under non-aqueous conditions with no gamma-Al2O3 observed in any calcination steps. As a result, well-crystalline ALN powder was obtained by the pyrolysis of urea-precursor above 900 degrees C under a stream of N-2 gas for 1 hour. In this process the urea-precursor decomposed below 400 degrees C, and an AW skeleton with a layer structure formed above 800 degrees C. The total yield of AN powder based on the Al atom was only 80% due to production of volatile Al(NH3)(6)AlH4Cl2 as a by-product. The AlN powder was characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy (SEM). Morphological observation of the ALN powder by mean of SEM revealed large particles of about 30-mu m diameter, which consisted of ultrafine particles of less than 1-mu m diameter.

  189. Atom insertion into the CoSb<inf>3</inf> skutterudite host lattice under high pressure 査読有り

    Takizawa, H., Miura, K., Ito, M., Suzuki, T., Endo, T.

    Journal of Alloys and Compounds 282 (1-2) 79-83 1999年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(98)00802-0  

    ISSN:0925-8388

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    CoSb3 with the skutterudite-type structure was synthesized by solid-state reaction and the atom insertion into the body-centered vacant site was attempted under high pressure and temperature conditions. Various 14-group elements were selected for atom insertion under pressure of 30 MPa to 5 GPa. It was found that various elements could be inserted in the body-centered vacant site, resulting in the formation of new filled-shutterudite phase MxCo4Sb12 (M=Si, Ge, Sn, Pb). The degree of insertion (x) increased with increasing the applied pressure. In the case of the Sn-CoSb3 system, nearly 40% of the body-centered vacant site was filled by Sn atom at 5 GPa. The crystal structure of resulting Sn0.4Co4Sb12 was refined by the Rietveld analysis of the X-ray diffraction data. (C) 1999 Elsevier Science SA. All rights reserved.

  190. 尿素-前駆体を用いた窒化アルミニウムの合成 査読有り

    上田恭太, 高橋祐之, 滝沢博胤, 遠藤 忠, 島田昌彦

    粉体および粉末冶金 45 (1) 31-35 1998年

    出版者・発行元:None

    DOI: 10.2497/jjspm.45.31  

    ISSN:0532-8799

  191. High Pressure Phase Transition of CrSb<inf>2</inf> 査読有り

    Takizawa, H., Uheda, K., Endo, T., Shimada, M.

    Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu 7 1043-1045 1998年

    DOI: 10.4131/jshpreview.7.1043  

    ISSN:1348-1940 0917-639X

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    Anew high-pressure phase of CrSb2has been synthesized from the marcasite-type ambient pressure phase by high-pressure/temperature treatment above 5.5 GPa. The crystal structure of the high-pressure phase is body-centered tetragonal, which is assigned as CuAl2-fype structure. The bond nature in the high-pressure phase is metallic, in contrast to the mixed ionic and covalent character in the marcasite-type phase. The phase transition, marcasite-type to CuAl2-type, accompanies 11% volume decrease and a change of d-electron character from localized to itinerant. © 1998, The Japan Society of High Pressure Science and Technology. All rights reserved.

  192. Synthesis and crystal structure of the oxygen defect perovskites containing copper and tantalum 査読有り

    Kato, S., Sugai, M., Ohshima, Y., Takizawa, H., Endo, T.

    Solid State Ionics 108 (1-4) 337-341 1998年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/s0167-2738(98)00060-5  

    ISSN:0167-2738

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    Perovskite-related solid solutions, Sr2-xLaxCu1-yTa1+yOz, were synthesized by solid state reaction at 1050-1080 degrees C in air. The crystalline phases were identified by powder X-ray diffraction. Three types of crystal structure were observed including simple cubic perovskite-type, tetragonal perovskite-type and tetragonally distorted (NH4)(3)FeF6-type structure in which Cu2+ and Ta5+ were ordered alternatively. The average valency state of copper in these solid solutions was nearly equal to + 2. The tetragonal phases were observed in a compositional range, z greater than or equal to 5.85, regardless of cation composition. The tetragonality (c/a) for both the perovskite-type and (NH4)(3)FeF6-type phases increased with increasing oxygen content. Ordering between Cu2+ and Ta5+ was not observed in the Sr-rich composition. These facts suggest that oxygen content affects the appearance of the Jahn-Teller effect of Cu2+ leading to the tetragonal distortion and that the cation on the A-site affects the ordering of the cation on the B-site. (C) 1998 Elsevier Science B.V. All rights reserved.

  193. Luminescence properties of rare earth ions in polytantalate 査読有り

    Kubota, S.-I., Yamane, H., Shimada, M., Takizawa, H., Endo, T.

    Journal of Alloys and Compounds 275-277 746-749 1998年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(98)00426-5  

    ISSN:0925-8388

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    The luminescence properties of R3+ (R3+=Eu3+, Tb3+, Tm3+) in La1-xRxTa7O19 solid solution were systematically examined. In this host lattice, the distance between nearest neighbors of the La3+ site which were substituted by the R3+ ions, were very long (about 0.62 nm) and the sites locate two-dimensionally. The critical concentration at which the concentration quenching occurred under UV excitation were x=1.0 in La1-xEuxTa7O19, x=0.9 in La1-xTbxTa7O19 and x=0.14 in La1-xTmxTa7O19. Furthermore the energy migration process of these samples were investigated. (C) 1998 Elsevier Science S.A.

  194. Microwave synthesis of yttrium iron garnet powder 査読有り

    Kimura, T., Takizawa, H., Uheda, K., Endo, T., Shimada, M.

    Journal of the American Ceramic Society 81 (11) 2961-2964 1998年

    出版者・発行元:AMER CERAMIC SOC

    DOI: 10.1111/j.1151-2916.1998.tb02720.x  

    ISSN:0002-7820

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    A 28 GHz microwave heating method was used to react an Fe2O3 + Y2O3 powder mixture to form yttrium iron garnet (YIG, Y3Fe5O12) powder. The minimum temperature to form YIG was lower than the conventional (external) heating method. YIG began to form after only 70 s of irradiation, which means that the solid-state reaction proceeded very rapidly. The amounts of byproducts were controlled by the starting composition and by the Y2O3 particle size. The resultant YIG particle size also was controlled by the Y2O3 particle size.

  195. Microwave synthesis of LaCrO<inf>3</inf> 査読有り

    Iwasaki, M., Takizawa, H., Uheda, K., Endo, T., Shimada, M.

    Journal of Materials Chemistry 8 (12) 2765-2768 1998年

    出版者・発行元:ROYAL SOC CHEMISTRY

    DOI: 10.1039/a804139c  

    ISSN:0959-9428

    eISSN:1364-5501

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    The synthesis of LaCrO3 from a. stoichiometric mixture of Cr2O3 and La2O3 powder by microwave irradiation was examined using a multi-mode 28 GHz microwave heating system. In the La2O3-Cr2O3 system, Cr2O3 strongly absorbs microwaves while La2O3 is transparent to microwaves. The reaction proceeded rapidly and LaCrO3 could. be synthesised within 15 min of irradiation. Surprisingly, the temperature required for the microwave synthesis (440 degrees C) is much lower than that for conventional, synthesis (&gt; 1200 degrees C) using an electric furnace.,The effect of the partial pressure of oxygen in the microwave chamber on the formation of LnCrO(3) was investigated. The formation of LnCrO(3) is enhanced with increase in the partial pressure of oxygen for Ln = La and Nd, while opposite behavior is seen for Ln = Gd, Tb, Dy and Ho.

  196. High-pressure synthesis and the magnetic properties of chromium diantimonide 査読有り

    H Takizawa, K Uheda, T Endo, M Shimada

    HIGH-PRESSURE MATERIALS RESEARCH 499 139-143 1998年

    出版者・発行元:MATERIALS RESEARCH SOCIETY

    ISSN:0272-9172

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    A new high-pressure polymorph of CrSb2, was synthesized under high-pressure/ temperature conditions of 7-7.7 GPa and 600-650 degrees C. The crystal structure is body-centered tetragonal with the space group I4/mcm, which is assigned to CuAl2-type structure. The experiments under various pressure conditions revealed that the high-pressure polymorph was formed above 5.5 GPa, and the compound crystallized into the low-pressure marcasite-type structure below 5 GPa. The characteristic of the high-pressure phase is the metallic bond nature including the formation of Cr-Cr-Cr linear chain along the c-axis. The compound shows metallic conductivity and itinerant-electron ferromagnetic behavior with the Curie temperature of ca. 160 K.

  197. ムライトを使用した炭化ケイ素多孔体の作製と機械的性質 査読有り

    宮川直通, 篠原伸広, 滝沢博胤, 遠藤忠

    無機マテリアル 4 (269) 350-355 1997年7月

    出版者・発行元:無機マテリアル学会

    DOI: 10.11451/mukimate1994.4.350  

    ISSN:1340-7899

  198. 窒化ケイ素を利用した炭化ケイ素多孔体の作製と機械的性質 査読有り

    宮川直通, 篠原伸広, 滝沢博胤, 遠藤 忠

    無機マテリアル 4 (269) 367-371 1997年7月

    出版者・発行元:無機マテリアル学会

    DOI: 10.11451/mukimate1994.4.367  

    ISSN:1340-7899

  199. 超高圧焼結により作製したβ-FeSi<SUB>2</SUB>系熱電材料の微細構造と熱電特性の異方性 査読有り

    滝澤博胤, 山本賢太, 遠藤忠, 島田昌彦

    粉体および粉末冶金 44 (1) 39-43 1997年

    出版者・発行元:None

    DOI: 10.2497/jjspm.44.39  

    ISSN:0532-8799

  200. Hydrothermal synthesis of Ni(IV) oxides 査読有り

    S. Uchida, H. Takizawa, M. Shimada

    Proceedings of the Fifth International Symposium on Hydrothermal Reactions 134-135 1997年

  201. Synthesis and long-period phosphorescence of ZnGa<inf>2</inf>O<inf>4</inf>:Mn<sup>2+</sup> spinel 査読有り

    Uheda, K., Maruyama, T., Takizawa, H., Endo, T.

    Journal of Alloys and Compounds 262-263 60-64 1997年

    出版者・発行元:ELSEVIER SCIENCE SA

    DOI: 10.1016/S0925-8388(97)00329-0  

    ISSN:0925-8388

    詳細を見る 詳細を閉じる

    Novel long-period phosphor ZnGa2O4:Mn2+ was prepared by a conventional solid reaction of ZnO, Ga2O3 and Mn(NO3)(2) under conditions of &gt; 1000 degrees C for 24 h in flowing Ar gas. The phosphor had green intense emission peaking at 503.6 nm. The improvement of emission intensity was brought out by the higher temperature processing. This implied that long lifetime phosphorescence was closely related to the formation of vacancies at the Zn2+ sites of the host lattice. The carrier trap level was positioned at 0.71 eV higher than the valence band of host lattice. The possible mechanism for prolonging the emission for a long time was discussed. (C) 1997 Elsevier Science S.A.

  202. Full-colored zinc gallate phosphor with graded composition 査読有り

    T Endo, K Uheda, H Takizawa

    FUNCTIONALLY GRADED MATERIALS 1996 701-706 1997年

    出版者・発行元:ELSEVIER SCIENCE PUBL B V

    詳細を見る 詳細を閉じる

    (Zn1-xMx)Ga2O4 (M = Cd2+, Mn2+) and Zn(Ga1-xMx)(2)O-4(M = Al3+,Cr3+) were prepared under the conditions of 1000 degrees C to 1400 degrees C for 3 to 24 h in air and flowing nitrogen or argon gas. The solid solutions were identified as a single phase with spinel structure. On doping Al3+ and Cd2+ ions, absorption edges were continuously changed with the concentration of dopant. In particular, the self-activated emission peak sifted to the positions in the range of 450nm to 570nm with increasing the x of (Zn1-xCdx)Ga2O4. The doped Mn2+ and Cr3+ ions functioned only as color centers, corresponding to the 3d-3d transitions. As a result, it was found that the intense emissions of ZnGa2O4 substitutes were essentially induced by the donor-acceptor recombination due to the graded and non-stoichiometric compositions.

  203. Phase transformation of Gd<inf>4</inf>Al<inf>2</inf>O<inf>9</inf> at high temperature 査読有り

    Shimada, M., Yamane, H., Takizawa, H., Endo, T.

    Key Engineering Materials 132-136 647-650 1997年

    出版者・発行元:Key Engineering Materials

    ISSN:1662-9795 1013-9826

  204. Synthesis and thermoelectric properties of Fe<inf>1-x</inf>Ru<inf>x</inf>Si<inf>2</inf> 査読有り

    Shimada, M., Mo, P., Odashima, Y., Uchida, S., Takizawa, H.

    Materials Science Forum 207-209 (PART 2) 681-683 1996年

    出版者・発行元:Materials Science Forum

    ISSN:1662-9752 0255-5476

    詳細を見る 詳細を閉じる

    beta-Fe(1-x-y)Fe(x)M(y)Si(2)(M=Cr,Co) solid solution is synthesized by solid state reaction at 1100 degrees C for 48 h and subsequent annealing at 850 degrees C for 168 h in an evacuated silica tube. Single phase is obtained in 0 less than or equal to x+y less than or equal to 0.1 and beta-phase is stable up to 1050 degrees C at x=0.1 (y=0). From the results of thermoelectric properties of high pressure sintered materials, the anisotropy of thermoelectric power is found. The value of thermoelectric power through the perpendicular direction for applied pressure is about 3 times as large as that of through the normal direction. The power factors of high pressure sintered materials are higher than those of pressureless sintered samples.

  205. Preparation and the crystal structure of ten-layer Ba<inf>5</inf>Fe<inf>4</inf>NiO<inf>13.5</inf> 査読有り

    Takizawa, H., Steinfink, H.

    Journal of Solid State Chemistry 121 (1) 133-137 1996年

    出版者・発行元:ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS

    DOI: 10.1006/jssc.1996.0019  

    ISSN:0022-4596

    詳細を見る 詳細を閉じる

    Ba5Fe4NiO13.5 (BaFe0.8Ni0.2O2.70) was synthesized by heating the mixed nitrates at 700 degrees C for 72 h in air, The crystal structure has been analyzed by Rietveld analysis of the powder X-ray diffraction data, Ba5Fe4NiO13.5 has a hexagonal unit cell, space group P6(3)/mmc with lattice parameters a = 5.7713(3) Angstrom and c = 24.5812(16) Angstrom. The structure is formed by the stacking of 10 close-packed BaO3 layers consisting of six hexagonal and four cubic sequences, This stacking creates trinuclear and binuclear face sharing octahedral units that are linked by corner sharing into a column approximately 24-Angstrom high, The Ni ion preferentially occupies the central octahedral interstice of the trinuclear unit and the Fe ions occupy all the other sites, The interatomic distances and the result of a magnetic measurement are consistent with the presence of 50% high-spin Fe4+, 50% high-spin Fe3+, and low-spin Ni3+ states. (C) 1996 Academic Press, Inc.

  206. High temperature orthorhombic phase of (R<inf>1-X</inf>La<inf>X</inf>)<inf>4</inf>Al<inf>2</inf>O<inf>9</inf> (R = Gd, Ho) 査読有り

    Takizawa, H., Kanou, S., Uchida, S., Shimada, M., Endo, T.

    Journal of Materials Science Letters 15 (1) 40-42 1996年

    出版者・発行元:CHAPMAN HALL LTD

    DOI: 10.1007/BF01855606  

    ISSN:0261-8028

  207. Energy migration in EuTa<inf>7</inf>O<inf>19</inf>, TbTa<inf>7</inf>O<inf>19</inf> and La<inf>0.86</inf>Tm<inf>0.14</inf>Ta<inf>7</inf>O<inf>19</inf> 査読有り

    Kubota, S.-I., Shimada, M., Takizawa, H., Endo, T.

    Journal of Alloys and Compounds 241 (1-2) 16-21 1996年

    出版者・発行元:ELSEVIER SCIENCE SA LAUSANNE

    DOI: 10.1016/0925-8388(96)02299-2  

    ISSN:0925-8388

    詳細を見る 詳細を閉じる

    The energy migration processes in EuTa7O19, TbTa7O19 and La0.86Tm0.14Ta7O19 are reported. The decay characteristics of the Eu3+ and Tb3+ emission can be explained by using a quasi-two-dimensional migration model, not by a two-dimensional migration model. In contrast, the characteristics of the Tm3+ emission can be explained by using the cross-relaxation energy transfer model.

  208. Periodic compounds from high pressure 査読有り

    T. Endo, H. Takizawa, M. Shimada

    Advanced Materials '96 125-130 1996年

  209. ガラスビ-ズを用いた炭化ケイ素多孔体の作製 査読有り

    宮川直通, 篠原伸広, 滝沢博胤, 遠藤 忠

    粉体および粉末冶金 43 (12) 1461-1465 1996年

    DOI: 10.2497/jjspm.43.1461  

    ISSN:0532-8799

  210. Synthesis and crystal structure of Sr<inf>2-x</inf>La<inf>x</inf>CuTaO<inf>y</inf> 査読有り

    Kato, S., Makita, T., Sugai, M., Ohshima, Y., Takizawa, H., Endo, T.

    Journal of Alloys and Compounds 243 (1-2) 36-38 1996年

    出版者・発行元:Elsevier BV

    DOI: 10.1016/S0925-8388(96)02371-7  

    ISSN:0925-8388

    詳細を見る 詳細を閉じる

    Perovskite related solid solutions Sr2-xLaxCuTaOy (0 ≤ x ≤ 1.0) were synthesized by solid state reaction at 1050°C in air. Two types of crystal structure were observed in the Sr2-xLaxCuTaOy system: simple cubic perovskite-type (0 ≤ x ≤ 0.7) and tetragonally distorted (NH4)3FeF6-type (0.8 ≤ x ≤ 1.0). The average valency state of copper in these solid solutions was nearly equal to + 2, which was determined by iodometric titration. A significant change of the cubic lattice parameter a was not observed, and the tetragonality (c/a) increased with increasing La3+ content. An ordering of Cu2+ and Ta5+ on the B site and the tetragonal distortion are found to be related to the appearance of the Jahn-Teller effect of Cu2+.

  211. Synthesis and Luminescence Properties of La<SUB>1-x</SUB>Tb<SUB>x</SUB>Ta<SUB>7</SUB>O<SUB>19</SUB>(0≦x≦1) 査読有り

    S.Kubota, T.Endo, H.Takizawa, M.Shimada

    Journal of Electrochemical society 142 (12) 4269-4272 1995年12月

    出版者・発行元:None

    DOI: 10.1149/1.2048495  

    ISSN:0013-4651

  212. Orthorhombic to monoclinic phase transformation of (Ho1-xLax)(4)Al2O9 by applying stress 査読有り

    M SHIMADA, H TAKIZAWA

    5TH INTERNATIONAL SYMPOSIUM ON CERAMIC MATERIALS AND COMPONENTS FOR ENGINES 418-421 1995年

    出版者・発行元:WORLD SCIENTIFIC PUBL CO PTE LTD

  213. High ionic conductivity and high fracture strength of cubic zirconia, (Y<inf>0.16 - x</inf>Sc<inf>x</inf>)Zr<inf>0.84</inf>O<inf>1.92</inf>,/alumina composites 査読有り

    Terauchi, S., Takizawa, H., Endo, T., Uchida, S., Terui, T., Shimada, M.

    Materials Letters 23 (4-6) 273-275 1995年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/0167-577X(95)00054-2  

    ISSN:0167-577X

    詳細を見る 詳細を閉じる

    Yttria- and scandia-doped cubic zirconia, (Ya(0.16-x)Sc(x))Zr0.84O1.92 (0 less than or equal to x less than or equal to 0.16),/alumina composites containing 0-20 vol% Al2O3 particles were sintered at 1600 degrees C for 5 h in air, followed by hot isostatic pressing at 150 MPa and 1500 degrees C for 1 h in Ar gas atmosphere. All sintered samples were densified above 99.5% of theoretical density. Both fracture strength and ionic conductivity greatly increased with increasing scandia content. For alumina particles dispersed cubic zirconia composites, fracture strength significantly increased, but ionic conductivity slightly decreased with increasing alumina content.

  214. Preparation and thermoelectric properties of β-Fe<SUB>1-x</SUB>Ru<SUB>x</SUB>Si<SUB>2</SUB> 査読有り

    H.Takizawa, P.F.Mo, T.Endo, M.Shimada

    Journal of Materials Science 30 (16) 4199-4203 1995年

    出版者・発行元:None

    DOI: 10.1007/BF00360731  

    ISSN:0022-2461 1573-4803

  215. Hydrothermal synthesis of iron and nickel oxides with high valence state 査読有り

    S. Uchida, H. Takizawa, M. Shimada

    Fourth-Euro Ceramics 1 31-36 1995年

  216. Luminescence of Eu<SUP>3+</SUP> in La<SUB>1-x</SUB>Eu<SUB>x</SUB>Ta<SUB>7</SUB>O<SUB>19</SUB> (0≦x≦1)Solid Solution 査読有り

    S.Kubota, T.Endo, H.Takizawa, M.Shimada

    Journal of Alloys and Compounds 217 (1) 44-47 1995年

    出版者・発行元:None

    DOI: 10.1016/0925-8388(94)01289-T  

    ISSN:0925-8388

  217. 希土類含有テルル酸ガラスのアップコンバ-ジョン発光特性 査読有り

    遠藤 忠, 田中 邦治, 滝沢 博胤, 島田 昌彦

    粉体および粉末冶金 42 (1) 61-66 1995年

    DOI: 10.2497/jjspm.42.61  

    ISSN:0532-8799

  218. LUMINESCENCE PROPERTIES OF LA1-XTMXTA7O19 査読有り

    S KUBOTA, T ENDO, H TAKIZAWA, M SHIMADA

    JOURNAL OF ALLOYS AND COMPOUNDS 210 (1-2) 103-108 1994年8月

    出版者・発行元:ELSEVIER SCIENCE SA LAUSANNE

    ISSN:0925-8388

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    The luminescence properties of Tm3+ in La1-xTmxTa7O19 solid solutions were examined systematically. The substitution of Tm3+ for La3+ was carried out by a decomposition reaction of nitrates involving the corresponding constituents of 1200-degrees-C in air. X-ray diffraction patterns of the solid solutions indicated that the crystal structure consisted of a network of (La1-x3+Tmx3+, Ta5+)-O2- polyhedra interstratified with a double layer of Ta5+-O2-polyhedra. According to the excitation and emission spectra, the most intense emission was found near 460 nm and quenched above x = 0.14 in La1-xTmxTa7O19. Also, lifetime results verified that the emission could be assigned not to the transition 1G4 --&gt; H-3(6), but to transition 1D2 --&gt; H-3(4). Upon cathode ray excitation some emissions of Tm3+ were superimposed by a broad emission due to the clusters of Ta5+-O2- polyhedra. As a result, a low dimensional arrangement of Tm3+ was much more preferable for getting intense emission because it reduced the energy migration between Tm3+ ions.

  219. Synthesis and thermoelectric properties of β-Fe<SUB>1-x</SUB>Ru<SUB>x</SUB>Si<SUB>2</SUB> 査読有り

    H. Takizawa, P. F. Mo, T. Endo, M. Shimada

    Proceedings of the 12th International Conference on Thermoelectrics 299-302 1994年5月

  220. Luminescence properties of La<inf>1-χ</inf>Tm<inf>χ</inf>Ta<inf>7</inf>O<inf>19</inf>

    Kubota, S.-i., Endo, T., Takizawa, H., Shimada, M.

    Journal of Alloys and Compounds 210 (1-2) 1994年

    DOI: 10.1016/0925-8388(94)90122-8  

    ISSN:0925-8388

  221. Sintering and Mechanical Properties of β-Wollastonite 査読有り

    T.Endo, S.Sugiura, M.Sakamaki, H.Takizawa, M.Shimada

    Journal of Materials Science 29 (6) 1501-1506 1994年

    出版者・発行元:None

    DOI: 10.1007/BF00368916  

    ISSN:0022-2461 1573-4803

  222. Multiphase composites of tetragonal zirconia agglomerate dispersed into alumina and alumina-zirconia matrices 査読有り

    Endo, T., Miyagawa, N., Takizawa, H., Shimada, M.

    Journal of Materials Science 29 (9) 2395-2400 1994年

    出版者・発行元:CHAPMAN HALL LTD

    DOI: 10.1007/BF00363432  

    ISSN:0022-2461 1573-4803

    詳細を見る 詳細を閉じる

    Multiphase composites of yttria- and ceria-doped tetragonal zirconia agglomerates (10-50 mum) dispersed into an alumina or alumina-zirconia matrix were sintered at 1500-1600-degrees-C in air, followed by post-Hot Isostatic Pressing (HIP) at 1450-degrees-C and 150 MPa in an Ar gas atmosphere. The relative density of the recovered composites was above 98% of the theoretical density. By chemically etching on the surface of zirconia agglomerates, the sinterability of composites was apparently improved; and no microcracks nor pores were observed at the interface of agglomerate and matrix. According to scanning electron microscopy (SEM) observation, tetragonal and tetragonal monoclinic zirconia agglomerates were highly dispersed into the alumina or alumina zirconia matrix. The multiphase composites containing 10 vol% spherical agglomerates demonstrate the relatively low value of bending strength, &lt; 400 MPa, and a high value of fracture toughness, &gt; 11 MPa m1/2. The crack propagation introduced by Vickers indentation was efficiently suppressed and deflected by the agglomerates.

  223. Stress‐Induced Phase Transformation in the Systems (Ho<inf>1−x</inf>La<inf>x</inf>)<inf>4</inf>Al<inf>2</inf>O<inf>9</inf> and (Y<inf>1−x</inf>La<inf>x</inf>)<inf>4</inf>Al<inf>2</inf>O<inf>9</inf> 査読有り

    Takizawa, H., Shimad, M., Shimoyashiki, K., Endo, T.

    Journal of the American Ceramic Society 77 (9) 2489-2490 1994年

    出版者・発行元:AMER CERAMIC SOC

    DOI: 10.1111/j.1151-2916.1994.tb04630.x  

    ISSN:1551-2916 0002-7820

    詳細を見る 詳細を閉じる

    New orthorhombic phases in (Ho1-xLax)(4)Al2O9 and (Y1-xLax)(4)Al2O9 systems have been synthesized by reaction sintering at 1600 degrees C for 30 h in air and have been metastably retained to room temperature. Stress-induced phase transformation from the orthorhombic phase to the monoclinic phase occurred in both systems. This phase transformation was accompanied by a 0.5% volume increase.

  224. HIGH-PRESSURE SYNTHESIS AND MAGNETIC-PROPERTIES OF T(1-X)T'(X)GE4 (T,T'-3D TRANSITION-METAL) 査読有り

    H TAKIZAWA, K YAMAZAKI, T ENDO, M SHIMADA

    HIGH-PRESSURE SCIENCE AND TECHNOLOGY - 1993, PTS 1 AND 2 1311-1314 1994年

    出版者・発行元:AIP PRESS

  225. Effects of divalent cation substitution on sinterability and electrical properties of lacro<inf>3</inf> ceramics 査読有り

    Jin, F., Endo, T., Takizawa, H., Shimada, M.

    Journal of Solid State Chemistry 113 (1) 138-144 1994年

    出版者・発行元:ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS

    DOI: 10.1006/jssc.1994.1352  

    ISSN:1095-726X 0022-4596

    詳細を見る 詳細を閉じる

    A series of LaCr1-xMxO3 (M = Mg, Cu, Zn, Ni) ceramics was fabricated by a conventional sintering process in air and Ar gas. Relative density, electrical conductivity, and magnetic susceptibility were measured to investigate the electrical conduction mechanism of the doped LaCrO3 ceramic. The apparent density was improved up to 95% of theoretical density, especially in the cases of M = Cu2+ and Zn2+. The electrical conductivity (sigma) increased with increasing quantities of doped divalent cation (x), and log(sigmaT) showed a linear relationship to (1/T). Magnetic data and chemical analysis indicated that the presence of Cr4+, rather than oxygen deficiencies, is preferential for the charge compensation. As a result, the electrical conduction was substantially governed by the hopping of small polarons between Cr3+ and Cr4+ ions. The substitution of Ni ions resulted in lower than expected unit cell volumes, somewhat different conductivities, and a different antiferromagnetic response, all of which pointed to the role of Ni3+ as of the source of an additional band conduction mechanism. (C) 1994 Academic Press, Inc.

  226. Ionic Conductivity and Mechanical Properties of Post-HIPed Cubic Zirconia/Alumina Composites 査読有り

    Terauchi, S., Takizawa, H., Endo, T., Shimada, M.

    Materials and Manufacturing Processes 9 (5) 965-974 1994年

    DOI: 10.1080/10426919408934963  

    ISSN:1532-2475 1042-6914

  227. Synthesis and electrical properties of (La<inf>1-x</inf>M<inf>x</inf>)<inf>3</inf>Ni<inf>2</inf>TaO<inf>9</inf> (M = Ca, Sr) 査読有り

    Kato, S., Sakamoto, T., Watanabe, N., Sugai, M., Ohshima, Y., Takizawa, H., Shimada, M.

    Materials Letters 21 (1) 101-104 1994年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/0167-577X(94)90131-7  

    ISSN:0167-577X

    詳細を見る 詳細を閉じる

    Perovskite related compounds (La(1-x)M(x))(3)Ni2TaO9(M=Ca, Sr), were synthesized by the metal nitrate decomposition method. Single-phase solid solutions were obtained in the composition range 0 less than or equal to X less than or equal to 0.20 in both (M=Ca, Sr) systems. The crystal structure of the solid solutions is slightly distorted (NH4)(3)FeF6-type structure. All the solid solutions exhibit p-type behavior with activation energies in the range from 0.13 to 0.22 eV. The value of the Seebeck coefficient of the solid solutions indicates the existence of hole carriers. The behavior of the compositional dependence of the unit cell volume indicates the presence of Ni3+ ions.

  228. Post-HIPing of yttria doped tetragonal zirconia/alumina composites 査読有り

    M. Shimada, N. Miyagawa, T. Endo, H. Takizawa

    Hot Isostatic Pressing '93 391-396 1994年

  229. A STRESS-INDUCED PHASE TRANSFORMATION OF (HO1-XLAX)4AL2O9 査読有り

    M SHIMADA, H TAKIZAWA

    PROCEEDINGS OF AN INTERNATIONAL CONFERENCE ON SOLID - SOLID PHASE TRANSFORMATIONS 829-833 1994年

    出版者・発行元:MINERALS, METALS & MATERIALS SOC

  230. LaCr<SUB>1-x</SUB>M<SUB>x</SUB>O<SUB>3</SUB>(M=Cu,Mg,Zn)の合成と電気的性質 査読有り

    金 富学, 滝沢博胤, 遠藤忠, 島田昌彦

    日本化学会誌 1993 (5) 670-672 1993年

    出版者・発行元:None

    DOI: 10.1246/nikkashi.1993.670  

    ISSN:0369-4577

  231. Tm<SUP>3+</SUP>付活YT<SUB>7</SUB>O<SUB>19</SUB> の蛍光特性 査読有り

    窪田俊一, 滝沢博胤, 遠藤 忠, 島田昌彦

    日本化学会誌 1993 (5) 630-634 1993年

    出版者・発行元:None

    DOI: 10.1246/nikkashi.1993.630  

    ISSN:0369-4577

  232. メチルニトロアニリン-リン酸複合体のソフトケミカルプロセッシング 査読有り

    内田 淑文, 遠藤 忠, 滝沢博胤, 島田昌彦

    粉体および粉末冶金 40 (10) 1002-1006 1993年

    DOI: 10.2497/jjspm.40.1002  

    ISSN:0532-8799

  233. High-pressure synthesis, crystal structure, and magnetic properties of Mn<inf>1-x</inf>T<inf>x</inf>Ge<inf>4</inf> (T: Co, Fe) 査読有り

    Takizawa, H., Yamazaki, K., Endo, T., Shimada, M.

    Journal of Solid State Chemistry 105 (2) 428-433 1993年

    出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE

    DOI: 10.1006/jssc.1993.1235  

    ISSN:1095-726X 0022-4596

    eISSN:1095-726X

  234. Synthesis and fluorescence properties of (Y<inf>1-x</inf>R<inf>x</inf>)<inf>2</inf>Te<inf>4</inf>O<inf>11</inf> (R = rare earths) 査読有り

    Endo, T., Shibuya, A., Takizawa, H., Shimada, M.

    Journal of Alloys and Compounds 192 (1-2) 50-52 1993年

    出版者・発行元:ELSEVIER SCIENCE SA LAUSANNE

    DOI: 10.1016/0925-8388(93)90183-N  

    ISSN:0925-8388

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    The preparation and luminescence properties of (Y1-xRx)2Te4O11 (R = rare earth) were examined and discussed to provide an understanding of the energy migration in the two-dimensional R3+ tellurates.

  235. High Pressure Synthesis of "Periodic Compound" and its Optical and Electrical Properties 査読有り

    T.Endo, H.Takizawa, M.Shimad

    New Functionality Mater. C 107-112 1993年

  236. High-pressure synthesis of MnSb<inf>2</inf> with the marcasite-type structure 査読有り

    Takizawa, H., Shimada, M., Sato, Y., Endo, T.

    Materials Letters 18 (1-2) 11-13 1993年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/0167-577X(93)90047-2  

    ISSN:0167-577X

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    The new dipnictide, MnSb2, has been synthesized by solid state reaction at 6 GPa and 650 degrees C. MnSb2 has the orthorhombic marcasite-type structure with lattice parameters a=0.60169(4) nm, b=0.68812(5) nm and c=0.33241(4) nm. This phase is the first marcasite-type transition metal dipnictide with formal 3d(3) electron configuration.

  237. Ba<SUB>0.5</SUB>Sr<SUB>0.5</SUB>CuO<SUB>z</SUB> A new perovskite related structure which forms at high pressure of 6 GPa 査読有り

    T. Sakurai, N. Sugii, H. Takizawa, M. Ichikawa, Y. Yaegashi, S. Adachi, M. Shimada, H. Yamauchi

    Advances in Superconductivity V 223-226 1993年

  238. High-pressure synthesis of new compounds, ZnSiN<inf>2</inf> and ZnGeN<inf>2</inf> with distorted wurtzite structure 査読有り

    Endo, T., Sato, Y., Takizawa, H., Shimada, M.

    Journal of Materials Science Letters 11 (7) 424-426 1992年

    出版者・発行元:CHAPMAN HALL LTD

    DOI: 10.1007/BF00728730  

    ISSN:0261-8028 1573-4811

  239. Ba<inf>0.5</inf>Sr<inf>0.5</inf>CuO<inf>z</inf>: a new perovskite related structure which forms at high pressure 査読有り

    Sakurai, T., Sugii, N., Takizawa, H., Ichikawa, M., Yaegashi, Y., Adachi, S., Shimada, M., Yamauchi, H.

    Physica C: Superconductivity and its applications 193 (3-4) 471-475 1992年

    出版者・発行元:ELSEVIER SCIENCE BV

    DOI: 10.1016/0921-4534(92)90973-G  

    ISSN:0921-4534

    詳細を見る 詳細を閉じる

    A new perovskite related structure was found in the sample of nominal composition of Ba0.5Sr0.5CuOz which was synthesized at a high pressure of 6 GPa. The space group for the new structure was determined to be Pmmm by means of a transmission electron microscopic observation. The lattice parameters were: a = 3.92 angstrom, b = 3.94 angstrom and c = 7.93 angstrom. In this structure, a cation ordering was revealed by means of a structural simulation. The ordering sequence of atomic layers was as follows: [Sr-CuO2-Ba-CuO2-Sr]. Although no evidences for superconductivity were obtained in the present work, it should be emphasized that compounds of this structure would exhibit superconductivity because CuO2 planes were contained in them.

  240. High-pressure synthesis of ZnSiP<inf>2</inf> and ZnGeP<inf>2</inf> 査読有り

    Endo, T., Sato, Y., Takizawa, H., Shimada, M.

    Journal of Materials Science Letters 11 (9) 567-569 1992年

    出版者・発行元:CHAPMAN HALL LTD

    DOI: 10.1007/BF00728610  

    ISSN:0261-8028 1573-4811

  241. Luminescence of Tm<sup>3+</sup>-doped YTa<inf>7</inf>O<inf>19</inf> 査読有り

    Kubota, S., Endo, T., Takizawa, H., Shimada, M.

    Journal of Materials Science Letters 11 (18) 1243-1245 1992年

    出版者・発行元:CHAPMAN HALL LTD

    DOI: 10.1007/BF00729780  

    ISSN:0261-8028 1573-4811

  242. Eu<sup>2+</sup> luminescence in Sr<inf>n+1</inf>Sn<inf>n</inf>O<inf>3 n+1</inf> with layered perovskite structure 査読有り

    Endo, T., Masuda, T., Takizawa, H., Shimada, M.

    Journal of Materials Science Letters 11 (19) 1330-1332 1992年

    出版者・発行元:CHAPMAN HALL LTD

    DOI: 10.1007/BF00742193  

    ISSN:0261-8028 1573-4811

  243. New II-IV-V<SUB>2</SUB> family of periodic compounds synthesized under high pressure 査読有り

    T. Endo, H. Takizawa, M. Shimada

    Ceramic Engineering and Science Proceedings 13 (9-10) 844-851 1992年

  244. Metal-Insulator Transition and Thermoelectric Properties in the System (R<SUB>1-x</SUB>Ca<SUB>x</SUB>)MnO<SUB>3-δ</SUB>(RTb,Ho,Y) 査読有り

    T.Kobayashi, H.Takizawa, T.Endo, T.Sato, M.Shimada, H.Taguchi, M.Nagao

    J.Solid State Chem. 92 (1) 116-129 1991年

    出版者・発行元:None

    DOI: 10.1016/0022-4596(91)90248-G  

    ISSN:1095-726X 0022-4596

  245. High pressure synthesis and electrical and magnetic properties of MnGe<inf>4</inf> and CoGe<inf>4</inf> 査読有り

    Takizawa, H., Sato, T., Endo, T., Shimada, M.

    Journal of Solid State Chemistry 88 (2) 384-390 1990年

    出版者・発行元:ACADEMIC PRESS INC ELSEVIER SCIENCE

    DOI: 10.1016/0022-4596(90)90232-M  

    ISSN:1095-726X 0022-4596

    eISSN:1095-726X

  246. High-pressure synthesis and electrical and magnetic properties of MnGe and CoGe with the cubic B20 structure 査読有り

    Takizawa, H., Sato, T., Endo, T., Shimada, M.

    Journal of Solid State Chemistry 73 (1) 40-46 1988年

    出版者・発行元:ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS

    DOI: 10.1016/0022-4596(88)90051-5  

    ISSN:1095-726X 0022-4596

  247. High-pressure synthesis and crystal structure of VGe<inf>2</inf> and Cr<inf>4</inf>Ge<inf>7</inf> 査読有り

    Takizawa, H., Sato, T., Endo, T., Shimada, M.

    Journal of Solid State Chemistry 73 (2) 427-432 1988年

    出版者・発行元:ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS

    DOI: 10.1016/0022-4596(88)90128-4  

    ISSN:1095-726X 0022-4596

  248. The synthesis of transition metal germanides under high pressure 査読有り

    M. Shimada, H. Takizawa, T. Endo, T. Sato

    High Pressure Geoscience and Material Synthesis (Proceedings of the XXV Annual Meeting of the European High Pressure Research Group 189-192 1988年

  249. 超伝導酸化物Ba<SUB>2</SUB>YCu<SUB>3</SUB>O<SUB>7-z</SUB>の酸素雰囲気合成と熱分析

    島田昌彦, 滝沢博胤, 佐藤次雄

    化学工業 1014-1021 1987年

  250. High-pressure synthesis and electrical properties of Mn<inf>3</inf>Ge<inf>5</inf> with Mn<inf>11</inf>Si<inf>19</inf>-type structure 査読有り

    Takizawa, H., Sato, T., Endo, T., Shimada, M.

    Journal of Solid State Chemistry 68 (2) 234-238 1987年

    出版者・発行元:ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS

    DOI: 10.1016/0022-4596(87)90308-2  

    ISSN:1095-726X 0022-4596

  251. PREPARATION AND ELECTRICAL PROPERTIES OF (M//1// minus //xM//x)Si//2 (M, M**1 equals Cr, Mn, Fe) (0 less than equivalent to x less than equivalent to 0. 3).

    Sato, T., Takizawa, H., Shimada, M.

    Physica Status Solidi (A) Applied Research 90 (1) 1985年

    ISSN:0031-8965

  252. Preparation and Electrical Properties of (M<SUB>1-x</SUB>M'<SUB>x</SUB>)Si<SUB>2</SUB> (M,M'=Cr, Mn, Fe) (0≦x≦0.3) 査読有り

    T.Sato, H.Takizawa, M.Shimada

    physica status solidi (a) 90 (1) K81-K86 1985年

    出版者・発行元:None

    DOI: 10.1002/pssa.2210900161  

    ISSN:1521-396X 0031-8965

︎全件表示 ︎最初の5件までを表示

MISC 71

  1. マイクロ波加熱を用いたペロブスカイト型酸化物を介したメタン改質反応の促進

    伊藤耕太郎, 松久将之, 椿俊太郎, 藤井知, 鈴木榮一, 福島潤, 滝澤博胤, 和田雄二

    日本化学会春季年会講演予稿集(CD-ROM) 99th 2019年

  2. Microwave synthesis of Ti<inf>4</inf>O<inf>7</inf> or AlN nanoparticles by rapid carbothermal reduction process

    Fukushima, J., Takizawa, H.

    Journal of the Japan Petroleum Institute 61 (2) 88-97 2018年

    出版者・発行元:Japan Petroleum Institute

    DOI: 10.1627/jpi.61.88  

    ISSN:1349-273X 1346-8804

    詳細を見る 詳細を閉じる

    Microwave processing was used to fabricate nanoparticles having a desired particle size and morphology by a simple method, carbothermal reduction method. By microwave processing, Ti4O7 nanoparticles (∼ 60 nm) maintaining the morphology of a pristine material were fabricated at 950 °C for 30 min. Since grain growth was observed in conventional processing, rapid heating (250 °C/min∼) and rapid cooling, which are features of the microwave processing, are also effective in maintaining the particle diameter even though this carbothermal reduction reaction proceeds in the high temperature region. In addition, we successfully synthesized spherical AlN nanoparticles with high nitridation rate, maintaining the morphology of pristine material by microwave processing. It is considered that the crystal structure of transition alumina (which is advantageous for formation of intermediate AlON but phase transition over 1200 °C) was maintained over 1300 °C by microwave rapid heating. In addition, by optimizing the nitrogen flow rate, spherical AlN nanoparticles having a nitridation ratio of 0.88 could be fabricated at 1200 °C for 180 min and a nitrogen flow rate of 0.2 L/min.

  3. 超音波による銀ナノ粒子の酸化処理銅ナノ粒子表面への担持と応用

    林 大和, 佐々木遼, 滝澤博胤

    ケミカルエンジニヤリング 62 (1) 53-61 2017年1月1日

    出版者・発行元:化学工業社

  4. 超音波・マイクロ波を利用した固液系金属ナノ材料合成技術に関する研究

    林 大和, 滝澤博胤

    粉体および粉末冶金 63 (11) 929-936 2016年

    出版者・発行元:Journal of the Japan Society of Powder and Powder Metallurgy

    DOI: 10.2497/jjspm.63.929  

    ISSN:0532-8799

  5. 超音波反応場を用いた低沸点溶媒中での粒子状グラファイトの直接剥離

    林 大和, 望月智文, 滝澤博胤

    超音波TECHNO 27 (3) 31-37 2015年6月1日

    出版者・発行元:日本工業出版

  6. 固−液系超音波反応を積極的に利用したAg/グラフェンナノコンポジットの合成

    林 大和, 望月智文, 滝澤博胤

    超音波TECHNO 26 (4) 23-31 2014年8月1日

    出版者・発行元:日本工業出版

  7. 超音波・マイクロ波反応場を利用した 固液系金属ナノ粒子プロセッシング

    林 大和, 滝澤博胤

    触媒 56 (1) 41-47 2014年2月1日

    出版者・発行元:日本触媒学会

  8. マイクロ波・ミリ波照射による新しい材料プロセッシング

    滝澤博胤

    セラミックス 49 (2) 101-105 2014年2月1日

    出版者・発行元:日本セラミックス協会

    ISSN:0009-031X

  9. マイクロ波照射によるラムスデライト型Li-Sn-O系新規化合物の合成

    中谷友哉, 福島潤, 林大和, 滝澤博胤, 川治純, 藤枝正, 浅利裕介

    セラミックス基礎科学討論会講演要旨集 52nd 2014年

  10. 固体電解質Na<sub>4</sub>Sn<sub>3</sub>O<sub>8</sub>におけるイオン拡散の第一原理解析

    浅利裕介, 川治純, 藤枝正, 林大和, 滝澤博胤

    応用物理学会秋季学術講演会講演予稿集(CD-ROM) 75th 2014年

  11. 第一原理計算による固体電解質Na<sub>4</sub>Sn<sub>3</sub>O<sub>8</sub>におけるナトリウムイオン拡散解析

    浅利裕介, 川治純, 藤枝正, 林大和, 滝澤博胤

    電気化学秋季大会講演要旨集 2014 2014年

  12. 電磁波エネルギーを利用した新しい無機材料プロセッシング

    滝澤博胤

    ペトロテック 36 (9) 710-714 2013年9月1日

    出版者・発行元:石油学会

    ISSN:0386-2763

  13. マイクロ波を用いた窒化チタンコーティング法

    滝澤博胤, 福島潤

    金属 83 (8) 30-35 2013年8月1日

    出版者・発行元:アグネ技術センター

  14. マイクロ波を利用した革新的材料プロセッシング〜特集にあたって

    滝澤博胤

    金属 83 (8) 667-668 2013年8月1日

    出版者・発行元:アグネ技術センター

  15. マイクロ波を用いた窒化チタンコーティング法

    滝澤博胤, 福島 潤

    金属 83 (8) 694-699 2013年8月1日

    出版者・発行元:アグネ技術センター

  16. 無機化学・材料化学におけるマイクロ波非平衡化学

    滝澤博胤

    電気学会誌 132 (1) 17-19 2012年

    出版者・発行元:The Institute of Electrical Engineers of Japan

    DOI: 10.1541/ieejjournal.132.17  

    ISSN:1881-4190 1340-5551

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    本記事に「抄録」はありません。

  17. 遷移金属-メタロイド系金属間化合物の高圧合成と物性評価

    菅野 雄大, 林 大和, 滝沢 博胤

    高圧討論会講演集 51 143-143 2010年10月11日

    ISSN:0917-6373

  18. 24pQA-5 マイクロ波によるナノ構造体・過飽和固溶体の形成(24pQA 領域2,領域3合同シンポジウム:マイクロ波テラヘルツ波による加熱の物理機構,領域2(プラズマ基礎・プラズマ科学・核融合プラズマ・プラズマ宇宙物理))

    滝澤 博胤

    日本物理学会講演概要集 65 (2) 184-184 2010年8月18日

    出版者・発行元:一般社団法人日本物理学会

    ISSN:1342-8349

  19. 24pQA-5 マイクロ波によるナノ構造体・過飽和固溶体の形成(24pQA 領域2,領域3合同シンポジウム:マイクロ波テラヘルツ波による加熱の物理機構,領域3(磁性,磁気共鳴))

    滝澤 博胤

    日本物理学会講演概要集 65 (2) 380-380 2010年8月18日

    出版者・発行元:一般社団法人日本物理学会

    ISSN:1342-8349

  20. ミリ波(28 GHz)およびマイクロ波(2.45 GHz)加熱における無機合成の特徴

    滝沢博胤

    材料技術 27 (4) 137-142 2009年7月25日

    出版者・発行元:材料技術研究協会

    ISSN:0289-7709

  21. -マイクロ波を用いた化学- 無機材料プロセッシング

    滝沢博胤

    色材協会誌 82 (2) 56-60 2009年2月20日

    出版者・発行元:Japan Society of Colour Material

    DOI: 10.4011/shikizai.82.56  

    ISSN:0010-180X

  22. マイクロ波選択加熱を利用した無機材料合成

    滝沢博胤, 青柳拓也, 林 大和

    材料の科学と工学 45 (3) 83-87 2008年6月20日

    出版者・発行元:日本材料科学会

    ISSN:1347-4774

  23. 低コスト・環境負荷低減型金属ナノ粒子プロセッシングとその応用

    林 大和, 滝澤博胤

    化学工業 59 (5) 15-21 2008年5月1日

    出版者・発行元:化学工業社

  24. 低コスト・環境負荷低減型金属ナノ粒子プロセッシングとその応用

    林 大和, 滝澤博胤

    化学工業 59 (5) 343-349 2008年5月1日

    出版者・発行元:化学工業社

  25. 機能性セラミックスのマイクロ波プロセッシング

    滝沢博胤

    Ceramic Data Book 2007 35 128-132 2007年10月19日

    出版者・発行元:株式会社テクノプラザ(工業製品技術協会)

  26. 連載開始にあたって

    大高 理, 滝沢 博胤

    高圧力の科学と技術 = The Review of high pressure science and technology 17 (1) 64-64 2007年5月20日

    ISSN:0917-639X

  27. トータル・エコデザインによる貴金属ナノ粒子材料のプロセス開発とその応用

    林 大和, 石川 大, 滝澤博胤, 井上雅博, 菅沼克昭, 新原皓一

    粉体および粉末冶金 54 (3) 186-193 2007年

    DOI: 10.2497/jjspm.54.186  

    ISSN:0532-8799

  28. ミリ波による金属の加熱と反応

    滝沢博胤, 林田千絵, 林 大和

    まてりあ 45 (8) 577-580 2006年8月20日

    出版者・発行元:日本金属学会

    DOI: 10.2320/materia.45.577  

    ISSN:1340-2625

  29. セラミックス系ナノコンポジット

    林 大和, 滝澤博胤, 新原皓一

    工業材料 54 (1) 70-71 2006年1月1日

  30. CoSb<SUB>3</SUB>を母体とした充填スクッテルダイト化合物の高圧合成と熱電特性

    滝沢博胤

    高圧力の科学と技術 16 (4) 322-328 2006年

    出版者・発行元:日本高圧力学会

    DOI: 10.4131/jshpreview.16.322  

    ISSN:1348-1940 0917-639X

  31. 超音波エコ・デザインによるナノ複合材料創製技術

    林 大和, 滝澤博胤

    マテリアルインテグレーション 18 (4) 33-38 2005年4月1日

    出版者・発行元:ティー・アイ・シー

  32. 無機化学・セラミックス分野におけるマイクロ波の利用

    滝沢博胤

    化学工学 69 (4) 214-217 2005年4月1日

    出版者・発行元:化学工学会

  33. 高メタロイド含有金属間化合物の高圧合成と結晶化学

    滝沢博胤

    高圧力の科学と技術 15 (4) 303-309 2005年

    出版者・発行元:Japan Society of High Pressure Science and Technology

    DOI: 10.4131/jshpreview.15.303  

    ISSN:1348-1940 0917-639X

  34. マイクロ波と物質の相互作用と材料プロセッシングへの応用

    滝沢 博胤

    材料とプロセス : 日本鉄鋼協会講演論文集 = Current advances in materials and processes : report of the ISIJ meeting 17 (1) 74-74 2004年3月1日

    ISSN:0914-6628

  35. 無機材料のマイクロ波プロセッシング

    滝沢博胤

    MATERIAL STAGE 3 (5) 42-46 2003年8月

    出版者・発行元:技術情報協会

  36. マイクロ波を利用した新しい材料創製

    滝沢博胤

    材料の科学と工学 40 (1) 7-12 2003年2月

  37. ミリ波照射による無機材料合成

    滝沢博胤, 木村禎一

    高温学会誌 29 (1) 26-32 2003年1月

  38. マイクロ波の無機材料合成への利用

    滝沢博胤

    化学工業 53 (10) 735-739 2002年10月

    出版者・発行元:化学工業社

  39. Eu<sup>2+</sup>イオンを賦活したCa-Al-Si-O-N系ガラスの合成と発光特性

    小松正和, 上田恭太, 滝沢博胤, 遠藤忠, 島田昌彦

    セラミックス基礎科学討論会講演要旨集 40th 2002年

  40. Erratum: Synthesis of Gd<inf>1-x</inf>Eu<inf>x</inf>Al<inf>3</inf> (Bo<inf>3</inf>)<inf>4</inf> (0 ≤ x ≤ 1) and its photoluminescence properties under UV and vacuum ultraviolet regions (Journal of the Electrochemical Society (2001) 148 (G430))

    Wang, Y., Uheda, K., Takizawa, H., Mizumoto, U., Endo, T.

    Journal of the Electrochemical Society 149 (6) L3-L3 2002年

    出版者・発行元:ELECTROCHEMICAL SOC INC

    DOI: 10.1149/1.1477920  

    ISSN:0013-4651

  41. 28GHzマイクロ波照射による無機材料合成

    滝沢博胤, 岩崎将任, 木村禎一, 上田恭太, 遠藤忠

    日本セラミックス協会秋季シンポジウム講演予稿集 14th 161 2001年9月26日

  42. マイクロ波照射による鉄複酸化物の合成

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠

    日本セラミックス協会年会講演予稿集 2001 140 2001年3月21日

  43. アルミニウムシリコンオキシナイトライドガラスの合成とその発光特性

    小松正和, 上田恭太, 滝沢博胤, 遠藤忠, 島田昌彦

    固体の反応性討論会講演予稿集 12th 2001年

  44. 希土類イオンを付活した窒化物および酸窒化物の合成と発光特性

    上田恭太, 小松正和, 滝沢博胤, 遠藤忠, 山根久典, 島田昌彦, XIE R J, 三友護

    希土類 (38) 2001年

    ISSN:0910-2205

  45. 層状化合物A_nNb_<n+3m>O_<3n+3m>[(ANbO_3)_n(NbO)_<3m>](A=Ba, Sr)の形成に及ぼすANbO_3(ペロブスカイト型)ブロックの格子サイズ・対称性の影響

    岩崎 航太, 滝沢 博胤, 上田 恭太, 山根 久典, 島田 昌彦, 遠藤 忠

    日本セラミックス協会学術論文誌 : Nippon Seramikkusu Kyokai gakujutsu ronbunshi 109 (1276) 1023-1027 2001年

    出版者・発行元:公益社団法人日本セラミックス協会

    DOI: 10.2109/jcersj.109.1276_1023  

    ISSN:0914-5400

    詳細を見る 詳細を閉じる

    The factors which influence the formation of layer structured A_nNb_<n+3m>O_<3n+3m>[(ANbO_3)_n(NbO)_<3m>](A=Ba, Sr), consisting of m-NbO blocks and n-ANbO_3 (perovskite type) blocks, were discussed. In the Ba_nNb_<n+3m>O_<3n+3m> system, compounds with a larger value of n/m ratio were synthesized at lower temperature than that with a smaller value of n/m ratio. Lattice constant of a-axis of these compounds decreased with increasing n/m ratio (Ba_2Nb_5O_9 (n/m= 2/1) [a= 0.4172 nm], BaNb_4O_6 (n/m= 1/1) [a= 0.4182 nm], BaNb_7O_9 (n/m= 1/2) [a= 0.4195 nm]). This tendency was also the same for the Sr_nNb_<n+3m>O_<3n+3m> system (Sr_2Nb_5O_9 (n/m=2/1) [a=0.4141 nm], Sr_2Nb_8O_<12> (n/m=2/2) [a=0.4166 nm]). On the other hand, when the amount of Ca substitution for Ba or Sr increased, (Ba, Ca)Nb_4O_6 (n/m= 1/1) and (Sr, Ca)_2Nb_8O_<12 >(n/m= 2/2) were formed instead of (A, Ca)_2Nb_5O_9 (n/m=2/1) at 1573 and 1673 K, respectively. These different tendencies can be explained in terms of matching of NbO block and ANbO_3 block. : Not only the difference of lattice sizes between NbO block and ANbO_3 block, but also the symmetric property in ANbO_3 block have large effects on the formation of A_nNb_<n+3m>O_<3n+3m>.

  46. 磁性材料 マイクロ波照射による鉄系複酸化物の合成と磁気特性 3

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠

    粉体粉末冶金協会講演概要集 2000 119 2000年5月16日

  47. マイクロ波照射によって作製したX線非晶質フェライトの磁気特性

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠

    日本セラミックス協会年会講演予稿集 2000 54 2000年3月21日

  48. Ca-Al-Si-O-N系オキシナイトライド蛍光ガラスの合成と発光特性

    上田恭太, 小松正和, 滝沢博胤, 遠藤忠

    日本セラミックス協会年会講演予稿集 2000 2000年

  49. アルミニウムシリコンナイトライドガラスの合成とその発光特性

    小松正和, 上田恭太, 滝沢博胤, 遠藤忠, 山根久典, 島田昌彦, WANG C-M, MITOMO M

    希土類 (36) 2000年

    ISSN:0910-2205

  50. 磁性材料 マイクロ波照射による鉄系複酸化物の合成と磁気特性 2

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠, 島田昌彦

    粉体粉末冶金協会講演概要集 1999 118 1999年11月9日

  51. マイクロ波照射による鉄複酸化物の合成と磁気的性質

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠

    日本セラミックス協会秋季シンポジウム講演予稿集 12th 289 1999年10月6日

  52. マイクロ波照射による鉄系複酸化物の合成と磁気特性

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠

    粉体粉末冶金協会講演概要集 1999 219 1999年6月1日

  53. LaSi_3N_5を母体材料とするセラミックス蛍光体の合成とその発光特性

    上田 恭太, 滝沢 博胤, 遠藤 忠, 山根 久典, 島田 昌彦

    希土類 = Rare earths (34) 220-221 1999年5月27日

    ISSN:0910-2205

  54. マイクロ波照射による鉄系複酸化物の合成

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠

    日本セラミックス協会年会講演予稿集 1999 509 1999年3月25日

  55. Cation Ordering in the Oxygen Deficient Perovskite Sr<sub>2-x</sub>La<sub>x</sub>Mg<sub>1-y</sub>Ta<sub>1+y</sub>O<sub>z・</sub>

    Sumio KATO, Eri OHMORI, Yoshinori SUZUKI, Yozo OHSHIMA, Mikio SUGAI, Hirotsugu TAKIZAWA, Tadashi ENDO

    Journal of Alloys and Compounds 107 (1243) 209-214 1999年

    DOI: 10.2109/jcersj.107.209  

    ISSN:0914-5400 1882-1022

  56. 熱電変換機能素材とは

    滝沢博胤

    金属 68 (12) 1059-1062 1998年12月

    出版者・発行元:アグネ

  57. 超高圧プロセスによる新材料開発

    滝沢博胤

    金属 68 (12) 1071-1077 1998年12月

    出版者・発行元:アグネ

  58. 硬質材料 マイクロ波照射による金属窒化物の合成

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠

    粉体粉末冶金協会講演概要集 1998 253 1998年11月

  59. 金属‐セラミックス複合体のマイクロ波合成

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠, 島田昌彦

    日本セラミックス協会秋季シンポジウム講演予稿集 11th 83 1998年10月

  60. イットリウム‐鉄系ガーネットのマイクロ波プロセッシング (2)

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠, 島田昌彦

    日本セラミックス協会年会講演予稿集 1998 216 1998年3月

  61. マイクロ波加熱によるY<sub>3</sub>(Fe,Al)<sub>5</sub>O<sub>12</sub>固溶体の合成

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠, 島田昌彦

    日本セラミックス協会秋季シンポジウム講演予稿集 10th 424 1997年10月

  62. 二次元空間における希土類ビスフェナントロリン錯体の分子構造とその発光特性

    上田 恭太, 朝木 則泰, 滝沢 博胤, 遠藤 忠

    希土類 = Rare earths (30) 176-177 1997年5月22日

    ISSN:0910-2205

  63. マイクロ波加熱によるY‐Fe‐O系複酸化物の合成

    木村禎一, 滝沢博胤, 上田恭太, 遠藤忠, 島田昌彦

    粉体粉末冶金協会講演概要集 1997 78 1997年5月

  64. 遷移金属-メタロイド系化合物の高圧合成

    滝沢博胤

    高圧力の科学と技術 6 (2) 102-108 1997年

    DOI: 10.4131/jshpreview.6.102  

    ISSN:1348-1940 0917-639X

  65. 希土類アルミネート(RE#D4#RAl#D2#RO#D9#R)の合成、結晶構造と相転移

    山根久典, 滝沢博胤, 大森 守, 平井敏雄, 島田昌彦

    東北大学素材工学研究所彙報 52 (1,2) 89-100 1996年12月

  66. 二次元空間での希土類ビスフェナントロリン錯体の作製と発光特性

    上田 恭太, 朝木 則泰, 滝沢 博胤, 遠藤 忠, 島田 昌彦

    希土類 = Rare earths (28) 278-279 1996年5月16日

    ISSN:0910-2205

  67. 粘土層間における希土類錯体の創製と蛍光特性

    朝木 則泰, 遠藤 忠, 滝沢 博胤, 島田 昌彦

    希土類 = Rare earths (26) 132-133 1995年5月11日

    ISSN:0910-2205

  68. アルカリ土類-銅系酸化物超伝導体

    滝沢博胤, 島田昌彦

    化学 48 (11) 804-805 1993年11月

    出版者・発行元:化学同人

  69. 遷移金属ゲルマニウム化物の構造と物性

    滝沢博胤, 島田昌彦

    素材物性学雑誌 4 (1) 64-74 1991年2月

    出版者・発行元:日本素材物性学会

    DOI: 10.5188/jsmerj.4.64  

    ISSN:0919-9853

  70. 遷移金属ケイ化物およびゲルマニウム化物半導体

    滝沢博胤, 島田昌彦

    化学 45 (12) 882-883 1990年12月

    出版者・発行元:化学同人

  71. アモルファス酸化物磁性体

    滝沢博胤

    化学と工業 42 (7) 1248-1249 1989年7月

︎全件表示 ︎最初の5件までを表示

書籍等出版物 15

  1. 固体材料の科学

    滝澤博胤, 田中勝久, 大友 明, 貝沼亮介

    東京化学同人 2015年6月25日

    ISBN: 9784807908585

  2. マイクロ波化学

    堀越 智, 篠原真毅, 滝澤博胤, 福島 潤

    三共出版 2013年12月10日

    ISBN: 9784782706961

  3. マイクロ波化学プロセス技術Ⅱ

    滝澤博胤, 福島潤, 章), 他

    シーエムシー出版 2013年1月7日

    ISBN: 9784781307060

  4. 材料科学・材料工学−基礎から応用まで−

    滝澤博胤, 関野 徹, 林 大和

    東京化学同人 2012年10月20日

  5. マイクロ波の化学プロセスへの応用

    滝沢博胤, ほか 監修, 和田雄二, 竹内和彦

    シーエムシー出版 2011年7月

    ISBN: 9784781303369

  6. セラミックスの事典

    山村博, 米屋勝利監修

    朝倉書店 2009年5月30日

    ISBN: 9784254252514

  7. 熱電変換技術ハンドブック

    滝沢博胤

    エヌ・ティー・エス 2008年12月20日

  8. マイクロ波化学プロセス技術

    和田雄二, 竹内和彦, 滝沢博胤

    シーエムシー出版 2006年3月22日

  9. 日本化学会編 第5版 実験化学講座6「温度・熱,圧力」

    滝沢博胤

    丸善 2005年7月30日

  10. 演習無機化学-基本から大学院入試まで-

    平尾一之, 田中勝久, 中平 敦, 幸塚広光, 滝澤博胤

    東京化学同人 2005年5月20日

  11. 日本化学会編 第5版 実験化学講座23「無機化合物」

    滝澤博胤

    丸善 2005年3月10日

  12. 初歩から学ぶマイクロ波応用技術

    マイクロ波応用技術研究会編著

    2004年6月

  13. マイクロ波の新しい工業利用技術

    柳田祥三, 二川佳男, 勝木宏昭, 加藤俊作, 滝沢博胤, 徳田昌生, 佐藤元泰, 和田雄二, 佐藤誠吾, 川島徳道, 笠井均, 篠塚秀利

    2003年11月

  14. 結晶化学入門

    遠藤 忠, 岩崎 博, 鶴見敬章, 中平 敦, 滝沢博胤

    2000年4月

  15. 日本化学会編、第4版実験化学講座4「熱・圧力」

    滝沢博胤, 島田昌彦

    1992年

︎全件表示 ︎最初の5件までを表示

講演・口頭発表等 34

  1. Role of Microwave Selective Heating on the Solid-State Synthesis of Divalent Sn Compounds 国際会議

    Nozomi Sato, Jun Fukushima, Yamato Hayashi

    The 15th International Symposium on Eco-materials Processing and Design 2014年1月12日

  2. マイクロ波を利用した材料プロセス革新〜電磁波エネルギーの産業応用加速化に向けて〜

    第7回日本電磁波エネルギー応用学会シンポジウム 2013年9月2日

  3. マイクロ波非平衡反応場を用いたナノ構造体の合成

    日本金属学会2012年秋期大会 2012年9月17日

  4. マイクロ波非平衡反応場を利用した先端無機材料プロセッシング

    平成24年度化学系学協会東北大会 2012年9月15日

  5. Toward the Next Stage of Innovative Materials Processing using Microwave Energy 国際会議

    2nd Global Congress on Microwave Energy Applications 2012年7月23日

  6. 超高圧力場・マイクロ波電磁場を反応場とした新材料創製の研究

    日本セラミックス協会2012年年会 2012年3月19日

  7. Microwave Synthesis of Nano-structured Materials in Zn-Fe-O System 国際会議

    The 13th International Symposium on Eco-materials Processing and Design 2012年1月7日

  8. 超高圧力場を反応場とした新物質探索

    日本学術振興会先進セラミックス第124委員会 2011年6月2日

  9. Formation of Nano-Scaled Modulated Structure in Zn-Fe-O System by Microwave Processing 国際会議

    Materials Science & Technology 2010 Conference & Exhibition 2010年10月17日

  10. マイクロ波によるナノ構造体・過飽和固溶体の形成

    日本物理学会平成22年度秋季大会 2010年9月23日

  11. Synthesis of High Performance ceramics Materials via Microwave Processing 国際会議

    12th International Ceramics Congress, CIMTEC 2010 2010年6月6日

  12. マイクロ波非平衡反応場を用いた材料プロセッシング

    平成22年度日本金属学会九州支部・日本鉄鋼協会九州支部・軽金属学会九州支部合同学術講演大会 2010年6月5日

  13. マイクロ波励起の非平衡反応場における革新的無機材料プロセッシング

    Microwave Workshops and Exhibition MWE2009 2009年11月25日

  14. 次のステージに向けて マイクロ波応用技術の目指すもの

    第3回日本電磁波エネルギー応用学会シンポジウム 2009年11月18日

  15. Materials Processing under Non-Equilibrium Reaction Field Induced by Microwave Irradiation 国際会議

    Materials Science & Technology 2009 Conference & Exhibition 2009年10月25日

  16. Microwave Processing of Advanced Inorganic Materials 国際会議

    The 1st International Symposium on Advanced Synthesis and Processing Technology for Materials 2008年11月14日

  17. Synthesis of Advanced Inorganic Materials under Non-equilibrium Reaction Field Induced by Microwave Irradiation 国際会議

    Global Congress on Microwave Energy Applications GCMEA 2008/ MAJIC 1st 2008年8月4日

  18. Rapid Synthesis of TiN by Microwave Irradiation and Its Application to Coating Technology 国際会議

    The 9th International Symposium on Eco-Materials Processing & Design 2008年1月7日

  19. マイクロ波を利用した先端無機材料プロセッシング

    日本化学会第87春季年会 2007年3月25日

  20. 28 GHzマイクロ波照射による窒化チタンの合成

    粉体粉末冶金協会平成18年度秋季大会 2006年12月5日

  21. Microwave Processing of Oxide Ceramics with Mesoscopic Structure 国際会議

    2005 International Nano Ceramics/ Crystal Forum and International Symposium on Intermaterials NCF9 & IMA9 2005年11月10日

  22. ミリ波による金属の加熱と反応

    日本金属学会2005年秋季大会 2005年9月28日

  23. Microwave Processing of Inorganic Materials using 28 GHz Frequency 国際会議

    The 6th International Symposium on Eco-Materials Processing & Design 2005年1月16日

  24. マイクロ波と物質の相互作用と材料プロセッシングへの応用

    日本鉄鋼協会第147回春季講演大会 2004年3月30日

  25. High Pressure Synthesis of Advanced Inorganic Materials 国際会議

    The 10th International Symposium on Advanced Materials 2003年3月10日

  26. Microwave Processing of Inorganic Materials Using 28 GHz Frequency 国際会議

    International Symposium on Innovative Materials Processing by Controlling Chemical Reaction Field 2002年11月27日

  27. 28 GHzマイクロ波プロセッシング-無機材料合成への展開-

    日本化学会第81春季年会 2002年3月26日

  28. ミリ波を用いた無機材料合成

    大阪大学接合科学研究所研究会"セラミックスの新プロセス技術" 2002年3月1日

  29. 28 GHzマイクロ波照射による無機材料プロセッシング

    第13回日本MRS学術シンポジウム 2001年12月20日

  30. High Pressure Synthesis of New Filled-Skutterudites 国際会議

    2001 Materials Research Society Fall Meeting 2001年11月26日

  31. スクッテルダイト系における材料設計

    科学技術交流財団 第5回新コンセプト熱電材料開発研究会 2001年7月5日

  32. スクッテルダイト構造への原子挿入と熱電特性

    東京大学物性研究所短期研究会"遷移金属酸化物の化学" 2001年6月18日

  33. ホウ素化合物の高圧合成と結晶化学

    日本応用磁気学会第1回化合物新磁性材料専門研究会"機能性セラミックスとしてのホウ化物" 2001年5月28日

  34. 金属-メタロイド系化合物の高圧合成

    日本高圧力学会 未来を拓く高圧力技術セミナーシリーズ15 "材料開発に応用できる高圧力技術" 1997年4月25日

︎全件表示 ︎最初の5件までを表示

産業財産権 1

  1. 窒化物コーティング法

    林田千絵, 滝澤博胤, 林 大和

    第4765069号

    産業財産権の種類: 特許権

共同研究・競争的資金等の研究課題 40

  1. 新規熱電変換材料の開発 競争的資金

    制度名:The Other Research Programs

    1996年4月 ~ 継続中

  2. 無機材料のマイクロ波合成 競争的資金

    制度名:Grant-in-Aid for Scientific Research

    1996年4月 ~ 継続中

  3. 遷移金属化合物の高圧合成 競争的資金

    制度名:Grant-in-Aid for Scientific Research

    1990年4月 ~ 継続中

  4. 高次探索空間におけるバルク準安定相のハイスループット合成とその創出プロセス確立

    福島 潤, 滝沢 博胤

    2022年4月1日 ~ 2027年3月31日

  5. マイクロ波ドライプロセスによるTiN表面改質のインプラントアバットメントへの応用

    伊東 明代, 小川 徹, 福島 潤, 洪 光, 滝沢 博胤, 佐々木 啓一

    2021年4月1日 ~ 2024年3月31日

    詳細を見る 詳細を閉じる

    TiNコーティングは, 硬度, 耐摩耗性, 耐食性等に優れ, 審美的な金色を呈すること, さらに抗菌性や生体親和性も期待されるため, 歯科インプラントアバットメント表面の機能向上にも適していると考えられる. しかし, 従来の成膜法(PVD法, CVD法等)では, アバットメントのような複雑な立体構造体への応用は難しく, 成膜プロセス上の煩雑さ, 安全面やコスト面においても様々な問題が残されている. マイクロ波ドライプロセスTiNコーティング法は,圧力や雰囲気置換を行わない大気中においてTiN形成が可能という独自性を持ち, 安価で簡便なプロセスであり, アバットメントへの応用に適している. 本研究は, 硬度, 耐摩耗性, 耐食性, 審美性, 細胞動態および軟組織封鎖性という観点から, マイクロ波ドライプロセスTiNコーティング法のアバットメント表面における最適成膜条件の探索を行い, トランスレーショナルリサーチの展開へ向けての基盤を形成する. 今年度は, 市販のアバットメントへの応用を想定した試料の作製・材料学的評価を進めた. Ti6Al4円盤(直径5mm, 厚さ1mm)にマイクロ波ドライプロセスによるTiNコーティングを施した試料を作製した. 反応時間は10分とし, 800℃, 850℃, 900℃, 950℃, 1000℃の反応温度でコーティングを施した. SEM像では全ての反応温度において波模様の微細構造を認めた. XRD分析の結果からは, 反応温度が高いほど窒化が進行しており, 950℃, 1000℃でTiNを認めた. この結果, 市販のアバットメントへの成膜条件として, 上記の反応温度が妥当であることが確認された.

  6. マイクロ波誘起非平衡状態の学理とその固体・界面化学反応制御法への応用展開

    和田 雄二, 滝沢 博胤, 堀部 雅弘, 荒川 智紀, 藤井 知, 田 旺帝, 吉川 昇, 西岡 将輝, 中村 考志, 福島 潤, 椿 俊太郎

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (S)

    研究機関:Tokyo Institute of Technology

    2017年5月31日 ~ 2022年3月31日

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    本課題はマイクロ波により固体表面、あるいは、固体バルクに生じる、局所的な非平衡状態の直接観測を武器として、マイクロ波によって固体・界面化学反応の学理を確立し、反応制御する方法論を確立することを目的とした。マイクロ波照射中の局所温度や物質構造を直接観測するin situ装置群の開発に成功し、従来、観測が不可能であった局所高温反応場の形成を実証し、これを理解する学理を得た。さらに、本手法が固体触媒反応や新材料合成反応を制御する方法として、その実用性を明確に示した。

  7. マイクロ波ドライプロセスによる歯科インプラントアバットメントのTiN表面改質

    伊藤 彩, 佐々木 啓一, 小川 徹, 佐藤 奈央子, 滝沢 博胤, 福島 潤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (C)

    研究機関:Tohoku University

    2017年4月1日 ~ 2020年3月31日

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    マイクロ波ドライプロセスによる新規のTiNコーティング法の歯科インプラントアバットメントの表面改質への応用を最終目標とし、本研究では、アバットメント用チタン合金における成膜条件の機械的・生物学的な最適化について検討を行った。その結果、特定条件でマイクロ波ドライプロセスTiNコーティングを施した表面では、優れた機械的特性に加え、インプラント周囲軟組織において、歯肉線維芽細胞の初期付着を促進する可能性があることが示唆された。

  8. メタロイド元素骨格への磁性原子団挿入による協奏機能発現-磁性半導体の新設計-

    滝沢 博胤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Challenging Exploratory Research

    研究機関:Tohoku University

    2015年4月1日 ~ 2017年3月31日

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    様々な電気的・磁気的特性の発現が期待できる遷移金属-メタロイド系金属間化合物の合成に超高圧力反応場を適用し、メタロイド共有結合骨格中に磁性金属鎖を挿入した新規金属間化合物の探索を行った。新規強磁性欠陥ダイシリサイド型金属間化合物Crn(Ge, Si)mの合成に成功し、そのキュリー点がm/nと強い相関性を持つことがわかった。また、新規フェリ磁性金属間化合物Mn(Al, Ge)5 の合成に成功し、低温におけるスピングラス的な挙動を確認した。

  9. マクロテトラヘドラルクラスター骨格を利用した新奇なリチウムイオン伝導体

    滝沢 博胤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Challenging Exploratory Research

    研究機関:Tohoku University

    2013年4月1日 ~ 2015年3月31日

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    本研究では、超高圧力反応場用いてLi-B-S系、マイクロ波反応場を用いてLi-Sn-O系新規Liイオン伝導性化合物を探索した。高圧合成法により新規相Li2B2S5の詳細な合成条件および結晶学的データの取得、およびマイクロ波合成法により新規相Li4xSn4-xO8の合成に成功した。Li2B2S5は単斜晶系の骨格構造がBS4面体の連結によって構成されており、一次元チャンネル内にLiイオンが配置していることが明らかとなった。また、Li4xSn4-xO8はラムスデライト構造を有し、一次元チャンネル内にLiイオンが配置していた。

  10. マイクロ波非平衡反応場を利用したSn含有マルチフェロイック新材料創製

    滝沢 博胤, 林 大和

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    2012年4月1日 ~ 2015年3月31日

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    本研究では、特異な原子価状態であるSn2+含有新規複酸化物の合成をマイクロ波プロセッシングにより行い、スズ2価含有酸化物の合成メカニズムを明らかにすることを目的とした。SnO-GeO2系において、マイクロ波照射により2相の新規相の合成に成功した。また、通常加熱による比較実験を通じた一連の研究から、急速加熱および非平衡反応場・一方向拡散が、Sn2+含有新規物質創製に重要な因子であることを明らかにできた。

  11. 軽元素共有結合性マクロテトラヘドラル化合物によるハイブリッド機能発現

    滝沢 博胤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Challenging Exploratory Research

    研究機関:Tohoku University

    2011年 ~ 2012年

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    造内間隙への低濃度イオン・原子挿入るイオン伝導性の発現や光学的機能設計を目指した。三系チオボレーのCaB_2S_4Li_2B_2S_5の成成功し前者ではEuの導入る緑色発光を観測した。本研究超力場を反応場としたネッワーの構築おび晶構造内隙への原子挿入能でると示された。

  12. 超高圧力場におけるホウ素含有クラスター化合物のナノ空間を利用した機能発現

    滝沢 博胤

    2010年 ~ 2011年

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    電気陰性度差の小さな軽元素同士の組合せからなる化合物は、強固な共有結合ネットワークからなる「隙間」の大きい結晶構造を有しており、1次元(トンネル)、2次元(層間)、3次元(クラスター空隙、空洞)チャンネルの利用が可能となる。本研究では、超高圧合成法をツールとして、ホウ素とイオウ原子を主成分としたrigidな格子空隙に種々のゲスト種を導入した新物質の探索を行った。Ca-B-S系については2種類の高圧相CaB_2S_4-II、CaB_2S_4-IIを合成し、CaサイトにEu^<2+>を置換した蛍光体の発行特性を調べた。励起・発光スペクトルを観測した結果、CaB_2S_4-II、CaB_2S_4-IIはいずれも緑色発光を示した。特に、BS_4四面体の多段連結からなるマクロテトラヘドラル構造を有するCaB_2S_4-Iは505nmにピーク波長をもつ強い緑色発光を示した。300~480nmに幅広い励起バンドをもつことから、青色LEDで励起可能な新材料であることが見出された。 一方、Caサイトがより高配位構造となるCaB_2S_4-IIの発光特性は、CaB_2S_4-Iとは異なり、2つの発光ピークが観測された。この2相ではEu^<2+>が置換するCaサイトの配位環境が大きく異なり、マクロテトラヘドラル構造によって形成される構造内のナノ空間が、発光特性のような機能発現において、特異な場を与えていることが示された。Eu^<2+>以外の他の希土類イオンもドープ可能であり、構造内ナノ空間に様々な発光中心を導入できることが明らかとなった。

  13. 新規マイクロ波加熱法の高度利用による環境・省エネルギー・材料プロセスの開発

    吉川 昇, 滝沢 博胤, 森田 一樹, 太田 和親, 松田 元秀, 亀岡 聡

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research on Priority Areas

    研究機関:Tohoku University

    2006年 ~ 2010年

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    最近になって解明されてきた、マイクロ波特有の加熱現象と新規なマイクロ波加熱プロセスを高度に利用して、その学理を検討した上で、材料プロセッシングや廃棄物処理等の環境技術への応用を開発した。電場/磁場を分離した加熱法の開発と金属粒子や薄膜のマイクロ波磁場による効率的加熱、強磁性共鳴加熱法の原理と磁性材料プロセッシング応用など基礎と応用を結びつける研究を行った。一方マイクロ波加熱の特徴を生かした環境処理、例えば急速加熱に依る鉄鋼スラブ処理、スラッジからの有用金属還元回収法の開発等により、プロセスの高効率化や省エネルギーに関する検討を行った。

  14. 超高圧力場を反応場とした軽元素共有結合ネットワークの構築と機能設計

    滝沢 博胤, 林 大和

    2007年 ~ 2008年

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    軽元素の共有結合ネットワークからなる結晶構造内のオングストロームサイズの空洞を「機能設計の場」と捉え、ゲスト種の導入によって電子・スピン・フォノンを独立に操り、ハイブリッド機能を発現し、モノリシック材料の多機能化を実現することを目的として、ホウ素と酸素、イオウからなる配位多面体を骨格とした新規物質を高圧合成法により探索した。ホウ素化合物の多くは、常圧下ではホウ素の平面3配位構造となるが、高圧力下ではsp^3配置によるBO_4やBS_4四面体の形成が促進され、これら四面体のネットワークから成る高圧相の形成が認められた。Ag-B-O系では、7GPa程度の圧力下で、新規化合物がアモルファス試料中に混在して生成し、そのIRスペクトルからBO_4四面体の形成が示唆された。温度、圧力をパラメーターとして結晶生成条件を詳細に調べることにより、褐色透明の単結晶を単離することに成功した。単結晶X線構造解析の結果、この新規物質はAg_<13>B_<11>O_<23>の化学組成で表される化合物で、BO_4四面体の頂点共有から成る結晶構造内の大きなケージに、Agイオンが統計的に分布した構造を有することがわかった。ケージ内ではAgイオンが大きな熱振動パラメーターを示すことから、ケージをチャンネルとしたイオン伝導性発現が期待できる。 メタロイド共有結合性化合物の物質探索では、新たにMnGe_4型新規物質群を見出し、その結晶構造を明らかにし、Mn-Mn距離に応じて強磁性が発現することを確認した。

  15. メゾスコピック機能材料のマイクロ波プロセッシング

    滝沢 博胤, 林 大和

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    2005年 ~ 2007年

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    新しい無機材料プロセッシングの構築を目的として、マイクロ波照射による非平衡反応下でナノ・メソスケール構造体を形成し、選択加熱系における熱的非平衡反応メカニズムの解明、非平衡反応下におけるナノ・メソスケール構造体の形成機構、格子・欠陥導入による電気的,磁気的,光学的物性制御手法の検討を行った。マイクロ波照射下での化学反応は、特定成分の選択加熱による微視領域での熱的非平衡反応としての特徴を有し、TiO_2-SnO_2系、Fe_3O_4-FeAl_2O_4固溶体のスピノーダル分解によるメゾスコピック組織形成が認められた。いずれも短時間のマイクロ波照射によって10〜30nmスケールに2相が積層したナノ組織の形成に成功した。電気炉加熱等の通常の化学反応では、スピノーダル分解による相分離組織形成には長時間の熱処理を要するが、マイクロ波照射下では微視領域での熱揺らぎにより固相拡散が促進され、極めて短い時間スケールでメゾスコピック組織の形成が可能となることを明らかにした。周波数の異なるマイクロ波を利用した材料プロセッシングを検討したところ、波長の長い2.45GHzのマイクロ波利用が有効であり、相分離の形成には物質内部へのマイクロ波侵入深さ(δ)が大きく影響することが明らかとなった。マイクロ波照射下での選択加熱は、基板上に形成された薄膜デバイスの結晶化にも有効であり、シリコン半導体基板上に形成されたPZT系誘電体薄膜の低温・短時間での結晶化も実現された。以上より、マイクロ波照射下の選択加熱の利用により、平衡組織から逸脱したマクロ・ミクロ組織形成が可能となることを実証した。

  16. マイクロ波プロセスによる階層構造構築と希土類機能発現

    滝沢 博胤, 林 大和

    2005年 ~ 2006年

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    TiO_2-SnO_2系は、固溶体が分相の際にスピノーダル分解を起こし、変調組織が数nmのメゾスコピック層状組織を形成することが知られている。スピノーダル分解は自己組織化反応であるため、熱処理のみの単純なプロセスでメゾスコピック組織を形成する。本研究では、28GHzと2.45GHzの2つの周波数のマイクロ波を用いて、TiO_2-SnO_2系に希土類元素をドープした場合のメゾスコピック組織形成と蛍光性発現を試みた。どちらの周波数のマイクロ波を用いた場合でも、固相拡散促進効果により、通常の固溶温度よりも低温・短時間での固溶が完了した。しかしマイクロ波加熱ではドーパントを添加しない場合、及びEu_2O_3のみを添加した場合もスピノーダル分解は進行せず、メゾスコピック組織の形成には至らなかった。本系に3価のカチオンを添加した場合、格子間カチオンが生成されるためにカチオンの移動度が増し、相分離速度が増加する。Eu_2O_3を添加した場合にはこの効果が顕著に現れなかった。これはEu^<3+>のイオン半径がTi^<4+>やSn^<4+>に比べて大きすぎるために、格子中へ固溶せず、相分離速度を増加させる程度の格子間カチオンが生成されなかったためと推察される。一方、Eu_2O_3と共に相分離速度の増加に有効であるAl^<3+>を添加した試料にマイクロ波を照射したところ、どちらの周波数から得られた試料もスピノーダル分解が進行していることが確認され、短時間かつ単純なプロセスでのメゾスコピック組織の作製に成功した。SnO_2単体へEu添加した場合にはEu^<3+>の磁気双極子遷移である^5Do→^7F_1遷移に起因するピークが観測されたが、固溶体及び相分離後の試料は蛍光性が低下した。スピノーダル相分離においては、微視的領域での濃度変動が組織形成に深く関与することから、マイクロ波照射下での選択加熱現象による微視領域での熱的非平衡状態の実現が鍵となっていると思われる。

  17. クラスレート化合物の機能設計のためのマクロクラスター結晶化学の構築

    滝沢 博胤

    2003年 ~ 2004年

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    無機化合物の結晶構造において、「クラスターユニットの相互連結によるマクロクラスター結晶化学」を構築する目的で、BS_4四面体の連結からなる巨大四面体クラスター形成とその結合様式について検討した。一価カチオンとしてAg、Li、Na、K、Cuを選択し、これとホウ素、硫黄の組合せからなる三元系化合物を高圧合成し、得られた生成物の結晶構造を解析した。Li-B-S系では二種の新規化合物(LiBS_2、Li_2B_8S_<13>)が生成し、このうちLi_2B_8S_<13>はB_2S_3高圧相の結晶構造を基本骨格とし、その空隙内にLiイオンが分布したマクロクラスター構造を有することが明らかとなった。Na-B-S、KB-S、Ag-B-S系では、それぞれ高圧合成により新規化合物が得られたが、単一相の合成が困難で詳細な結晶構造解析には至らなかった。しかし、赤外吸収スペクトルからはBS_4四面体からなるクラスターユニットの存在が示唆され、一価カチオンを含む三元系ホウ硫化物にはマクロクラスター構造が多数出現することが見出された。一方、Cu-B-S系ではカルコパイライト型構造の新規化合物CuBS_2が得られ、バンドギャップが3.6eVのワイドギャップ半導体であることが判明した。マクロクラスター構造の構築と一価カチオンのイオン半径との間には明瞭な相関が存在し、イオン半径が小さいほど、BS_4四面体の連結からなるマクロクラスター構造が形成されやすいことが明らかとなった。高圧力場は構成イオン間のイオン半径比に大きく影響を及ぼすため、これらの化合物群の合成には有利な反応場である。以上、本研究により、三元系ホウ硫化物に特異に発現するマクロクラスター構造が明らかになったとともに、その構造形成がクラスターユニットに含まれない一価カチオンのサイズに大きく依存することを見出した。

  18. ホウ素クラスター化合物の電磁波誘起磁気秩序化

    滝沢 博胤, 上田 恭太, 遠藤 忠

    2001年 ~ 2002年

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    β-菱面体晶ホウ素はB_<12>正二十面体とB_<28>ユニットを含むクラスター構造を有し,ホウ素の3中心結合による内因性アクセプターによる局在化準位の形成等,物性発現の観点から興味深い。本研究では,マイクロ波吸収の強いβ-菱面体晶ホウ素に微量の遷移金属原子をドープし,マイクロ波照射による「ホウ素を介在したドープ金属間の相互作用発現」による磁気秩序化について検討した。Mn, Fe, Co, Cuをドープした試料を作製し,X線回折データのリートベルト解析を行った結果,β-ホウ素中の3種のドーピングサイトの占有傾向が遷移金属原子の種類により異なることが示された。磁気測定の結果,2種の遷移金属を同時ドープした試料では,極低温域で反強磁性的相互作用の存在が示唆され,構造解析結果と合わせると,ホウ素を介在した2種の遷移金属間の相互作用によるものであると推測された。Co, Cuを同時にドープした試料では,室温の磁化曲線がヒステリシスを描き,弱い強磁性の存在が示唆されたが,その詳細の解明には至らなかった。一方,電気伝導度はドープした金属の種類,ドーピング量に依らず,いずれもバリアブルレンジホッピング型の温度変化を示した。ドーピングサイトの占有傾向により伝導度の増大,減少が認められ,ドーピング元素が形成する局在化準位の深さに大きく支配されることが明らかとなった。高出力のマイクロ波照射下で合成したFeB_x、では,室温においても強磁性的挙動を示すことが認められた。構造解析結果からは照射前後でFeサイトの占有率,座標には大きな違いは認められず,部分的にFeB相のような強磁性的クラスターが生成した可能性がある。

  19. アモルファスフェライト磁性体のマイクロ波合成と機能化に関する研究

    滝沢 博胤, 上田 恭太, 遠藤 忠

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    2000年 ~ 2002年

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    マイクロ波照射による材料プロセッシングにおいては,物質のマイクロ波吸収に伴う自己発熱を利用した内部加熱や選択加熱等の熱的効果に加え,交番電磁界中での反応に起因する非熱的効果が重要である。非熱的効果に基づく現象として,高強度のマイクロ波照射下でフェライトがアモルファス化する現象があり,これはマイクロ波電磁界中での構造揺らぎに起因する。本研究では28GHzのマイクロ波を用い,種々のフェライトのマイクロ波吸収特性を評価し,スピネル組成やマグネトプランバイト組成の鉄複酸化物系において,新規のアモルファス相が生成することを見出した。また,低酸素分圧下ではマイクロ波吸収が強くなり,かつ結晶性の低下が顕著になることを見いだした。結晶性の低下はマイクロ波の照射出力を増大させても引き起こされることから,マイクロ波吸収エネルギーの増大に伴う構造の揺らぎがアモルファス化の要因であることが明らかとなった。正スピネル構造で反強磁性を示すZnFe_2O_4は,高出力のマイクロ波照射あるいは低酸素分圧下でのマイクロ波照射によって強い磁化を示すようになった。これは,マイクロ波交番電磁界中でのイオンの揺動により,(111)面がすべり面となり,この転位の導入によって結晶構造に乱れを生じるとともに,Fe^<3+>イオンが八面体サイトから四面体サイトへ移動したものと推測される。得られたアモルファス相は,同組成の結晶相に比べ,飽和磁化やキュリー点はほぼ等しいものの,抗磁力は小さくソフトな磁性体であった。このアモルファス相は熱的には安定であるが,せん断応力により結晶化するなど,特異な特徴を示した。 以上,本研究により,マイクロ波照射下でのフェライトのアモルファス化メカニズムに関する知見が得られ,かつマイクロ波吸収エネルギーを変化させることによって,フェライト相の磁化,抗磁力等の諸物性を制御できることを明らかにした。

  20. スピネル関連酸化物発光体の機能化とその応用

    遠藤 忠, 左合 澄人, 上田 恭太, 滝沢 博胤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    1999年 ~ 2001年

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    本研究では、スピネル関連構造のマグネットプランバイトを中心に結晶構造の次元性に着目して、結晶化学を背景に新しい蛍光表示パネル用(VFD)高輝度発光体として利用できる可能性について検討することを目的とする。 一方で、電子線励起による発光体では、結晶構造においてNaClブロックに発光イオン種を配置し、スピネルブロックからなる骨格に電気伝導性を持たせる必要性がある。こうした材料設計的な視点から、13年度は新たにパイロクロア型構造を有する錫酸化物を対象として、VFD用蛍光体としての可能性について探った。具体的には、パイロクロア(A_2B_2O_7)構造を有する化合物について、その結晶構造内で、Aイオンに発光イオン種を、Bイオンと酸素原子(O)がつくる骨格に電子伝導機能の役割をもたせた新規VFD用発光体の探索研究を行う。 Aイオンには、発光中心イオンとして種々の3価の希土類イオンを用いた。一方、BイオンにはTi^<4+>、あるいはSn^<4+>を選択した。始めに出発原料としてLn_2O_3(Ln:希土類元素)、MO_2(M=Ti・Sn)を用い、パイロクロア型構造を有した母体材料の合成を検討した。得られた母体材料はX線・電子回折法を用いて相同定あるいは結晶構造解析を行った後、それぞれ得られた母体材料の最適合成条件を決定した。 特にAイオンの位置にEu^<3+>、Pr^<3+>イオン等の希土類イオンを固溶置換によって付活した新しいVFD用発光体の合成に成功した。合成された発光体は紫外・可視分光光度計をはじめとする分光測定装置を用いて発光特性を測定し、母体材料へ付活するイオン濃度の最適化を図った。このようにして合成したVFD用発光体は、カソードルミネセンス測定により実用化に向けた特性評価を行った。 次いで、プラズマディスプレイパネル(PDP)用高輝度発光体の母体材料には、スピネルブロックをもつホウアルミン酸塩基を対象に材料設計を行った。147nmの励起エネルギーを吸収するアニオン部(BO_3)と可視光を放射するカチオン部とが組み合わさったCaAl_2B_2O_7;Eu^<2+>発光体の合成に初めて成功した。

  21. 超高圧力場を利用したインターカレーション反応による新規無機材料の合成

    滝沢 博胤, 上田 恭太, 遠藤 忠

    1999年 ~ 2000年

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    本研究では,1次元から3次元の空洞構造を有する無機化合物(ホスト)への原子・分子挿入反応を超高圧力下で行い,静電的あるいは分子間相互作用を駆動力として行われてきた従来のインターカレーション反応とは異なる,超高圧条件がもたらす系の体積減少効果に着目した新しい反応設計を行うことを主眼とした. 1次元(トンネル)〜3次元(空孔)空間を有する無機化合物ホストと,ゆるやかに結合したゲスト種とのホスト-ゲスト相互作用による母材料の機能制御・新機能発現を目指し、新たな材料設計指針を構築することを目的とした.1次元空洞構造としてVS_6八面体2×2サイズのトンネルを有するA_xV_5S_8を高圧合成し,常圧合成に比べてトンネル内の原子占有比の高い化合物を得た.得られた物質は高い電子伝導性を示した.一方,3次元空洞構造であるスクッテルド鉱型構造を有する無機ホストへは,超高圧力下において種々の金属原子の挿入が実現できることを明らかにした.この反応は圧力の上昇とともに容易に進行し,8GPa領域においては母格子の空洞をゲスト原子で完全に占有することが可能であった.母体とゆるやかに結合したゲスト原子の挿入は,母体の半導体性を失うことなく,母格子内で大きな熱振動を示し,"rattling効果"による熱伝導率の大幅な低減をもたらすことがわかった.空隙サイズと挿入原子のサイズにより,母格子中での挿入原子の原子座標や熱振動に違いが現れることも判明した.本手法により得られたSn_xCo_4Sb_<12>化合物は,スクッテルダイト系としては最も低い熱伝導率を示し,かつ大きな熱電能と高い電気伝導度を示すことから,熱電変換材料として有望である.

  22. トンネル型構造をもつ錫系複酸化物の合成と電気的性質

    遠藤 忠, 上田 恭太, 滝沢 博胤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B).

    研究機関:Tohoku University

    1998年 ~ 2000年

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    本研究は結晶構造内に空洞や細孔を有し,典型元素酸化物であるSnO_2を主成分とする新しい複酸化物の探索である.これまでに,SnO_6八面体(1×2)個分のトンネル内にLiイオンを有したラムスデライト型構造を持つLi_2MgSn_3O_8が報告されてきた.そこで,このトンネル内に存在するLiイオンより大きなアルカリイオン種,K,Rbイオンなどを用いてホーランダイト(2×2),ロマネカイト(2×3),トドロカイト(3×3)型構造からなる化合物の創製を検討した.その結果,ホーランダイト型構造を有する単斜晶系のA_xMg_<x/2>Sn_<8-x/2>O_<16>(x≦2)(K,RbとCs)とK_xCa_<x/2>Sn_<8-x/2>O_<16>(x≦2)を新たに合成した. さらに,これら新しい化合物がイオン伝導および電子伝導性を併せもち,広い温度域で高い伝導度を示すことを期待した.そこで,K_xCa_<x/2>Sn_<8-x/2>O_<16>を例にとり,この化合物の電気的性質を評価するため,フラックス法を用いた単結晶育成を検討した.過剰なK_2CO_3をフラックスとすることによって,K_xCa_<x/2>Sn_<8-x/2>O_<16>(x≦2)の繊維状結晶が一方向に束なった1.5mm×0.2mm×0.2mmの大きさをもつ多結晶体が得られた.こうして得られた多結晶体について導電率を測定することにより,室温における導電率:σ_<300>=2.2×10^<-9>Ω^<-1>・m^<-1>,活性化エネルギー:0.63eVを求めることができた.これら値は空間的に制限されたトンネル内におけるKイオンによるイオン伝導であると結論できた. 本研究により,新しいホーランダイト型化合物A_xMg_<x/2>Sn_<8-x/2>O_<16>(x≦2)(K,RbとCs)とK_xCa_<x/2>Sn_<8-x/2>O_<16>(x≦2)のイオン伝導体材料への応用が期待できた.

  23. 高機能ディスプレイ用新規高輝度発光材料の開発研究

    島田 昌彦, 上田 恭太, 窪田 俊一, 滝沢 博胤, 清水 悦雄, 長谷 堯, 長谷 尭堯

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:TOHOKU UNIVERSITY

    1997年 ~ 1999年

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    本研究では蛍光体母結晶として、これまでにその可能性が明らかでなかったLiSr_2YO_4,SrLaGa_3O_7,CaLaAl_3O_7とLaTa_7O_<19>を対象にEu^<3+>イオン、Tb^<3+>イオン、Tm^<3+>イオンを付活した赤色、緑色、青色蛍光体を各々合成し、発光特性評価を行いその結晶構造との相関性を検討した。所定の温度・雰囲気で焼成することにより、LiSr_2Y_<1-x>RE_xO_4とSrLa_<1-x>RE_xGa_3O_7(RE=Eu,Tb,Tm)の全固溶域において単一相を合成し、固溶体の発光特性の発光元素濃度依存性を評価した。LiSr_2Y_<1-x>Eu_xO_4では赤色発光を示し、x=0.15をピークとして付活剤濃度の増加と共に発光強度は減少した。一方、SrLa_<1-x>Eu_xCa_3O_7の赤色発光強度の濃度依存性は、x=0.2とx=0.8付近に2つのピークが観測され、メリライト型構造におけるEu^<3+>イオンのペア配置によると考えられた。本研究における蛍光体の発光強度と母結晶中の希土類イオン間の距離との関係において、最近接希土類イオン間距離に注目すると、層間の距離のほぼ等しいBaEu_2Ti_3O_<10>とEuTa_7O_<19>は層内の距離が増加するにつれて、励起エネルギーの消失が抑制され発光強度が強くなることが判明した。鎖内と層内の距離がほぼ等しい蛍光体では、母結晶の結晶構造の低次元化が発光強度と密接に関係していることも明らかとなった。ー方、メリライト型構造を母結晶とした場合は、発光希土類元素のペアを組ませてペア同士の距離を離すことにより、エネルギー移動を抑制して単位体積当たりの発光希土類元素濃度を上げる事が可能であることも明らかとなった。 蛍光体の発光強度と母結晶中の希土類イオン間の距離と配置の次元性とは密接な関係があり、本研究によってこれまで報告されていない新規母結晶蛍光体の作製に成功し、結晶構造と発光特性との相関性について詳細な検討を行い、高輝度発光材料を開発する一つの指針を得ることができた。

  24. 超高圧合成による新規遷移金属化合物の探索と結晶化学

    滝沢 博胤, 山根 久典, 島田 昌彦, 上田 恭太

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:TOHOKU UNIVERSITY

    1997年 ~ 1999年

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    3d遷移金属-メタロイド原子系金属間化合物は,結合の性質が金属結合性にイオン性,共有性が加味され,結晶化学,磁性や電気伝導の振る舞いにおいて興味深い物質群であり機能材料の宝庫ともいわれる.本研究では,遷移金属-メタロイド原子系化合物の超高圧・高温反応,超高圧力下における空格子サイトヘの原子挿入による新規充填構造物質の合成,の2つの視点に立ち,超高圧力下を反応場とした新規遷移金属化合物の探索研究を行い,新しい機能性無機材料の設計に資することを目的とした. 1.遷移金属二アンチモン化物(TSb_2)は常圧下においてマーカサイト型構造を有しており,その結合は多分にイオン性を含み形式電荷はT^<4+>[Sb_2]^<4->で表される.超高圧力下での合成を行った結果,CrSb_2においては6GPa以上の圧力領域においてCuA1_2型構造の新規高圧相を得た.マーカサイト型常圧相における局在的な3d電子の性質は,圧力誘起相転移により遍歴性を帯び,遍歴電子による強磁性をしめすようになることを明らかにした.さらに,NiSb_2においてはNiSb_6八面体が稜共有と頂点共有で連結した新しい高圧相を合成し,これらの結果から高圧下における遷移金属プニクタイド,カルコゲナイドの高圧力下の高圧相転移を系統化した. 2.体心位置に大きな空洞を有するCoSb_3の結晶格子に,超高圧力下における原子挿入を行い,一連のM_XCo_4Sb_<12>化合物を新たに合成した.特にM=Ge,Sn,Pbを挿入した実験結果から,挿入原子と骨格構造との"結合の強さ"には,挿入原子のサイズ効果が影響することを明らかにした.挿入原子は空洞内で大きな熱振動を示し,その結果として格子熱伝導率の大幅な低減が起こることが判明した.この結果は,新規熱電変換材料の開発研究に重要な指針を与えるものである.

  25. 超臨界水中での水熱合成による蛍光体微粒子連続合成プロセスの開発

    新井 邦夫, 伯田 幸也, 滝澤 博胤, 亜尻 雅文, R. L Smith, 猪股 宏

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (A)

    研究機関:Tohoku University

    1996年 ~ 1997年

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    本研究の目的は、超臨界水晶折法により蛍光体微粒子YAG;Tbの高速かつ連続合成プロセスの開発である。反応条件(反応温度、圧力、反応時間、溶液組織、アルカリモル比)と生成した粒子の性状(結晶構造、粒子サイズ、サイズ分布)の関係について実験的に検討した。その結果、反応時間が1秒で単一相YAG微粒子が連続合成(収集1g/h)できた。また、アルカリモル比が単一相のYAG粒子を合成するために極めて重要な因子であることがわかった。また、反応温度および反応圧力は、結晶子サイズおよび結晶の格子定数に大きく影響することがわかった。高温かつ低圧力条件とすることで、結晶性が向上することがわかった。また、生成粒子の発光特性を測定し、従来法である固相法で合成との比較を行った。励起、発光スペクトルともに両者ともYAG母体結晶の吸収およびTbイオンの発光に帰依するものであったが、その発光強度は、本手法で合成した粒子のものは、固相法のものの約10%であった。これは、粒子内に残存したOH基のため、吸収されたエネルギーがTbイオンへの伝播されず、結晶内で消費されてしまったものと推察している。これは、反応温度または反応時間の増加させることで結晶性および発光特性を改善できると考えている。超臨界水中での反応晶折法が、蛍光体微粒子の連続合成法として有効であり、プロセス化への高い可能性が示された。

  26. 新規3d遷移金属-ゲルマニウム系電子化合物の超高圧合成

    滝沢 博胤, 上田 恭太

    1996年 ~ 1996年

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    超高圧力下で合成された新規遷移金属ゲルマニウム化物、T_<1-x>T'_xGe_4 (T, T' : 3d遷移金属)は、3d遷移金属原子の平均価電子数と寸法因子により、その結晶構造が変化し、新規電子化合物群である可能性が示唆される。本研究では結晶構造決定因子を解明し、遷移金属四ゲルマニウム化物を新規化合物群として体系化することを目的とした。 2元系化合物としては、MnGe_4、FeGe_4、CoGe_4の3相が生成するのみであるが、種々の遷移金属の組合わせからなる擬2元系化合物T_<1-x>T'_xGe_4 (T, T' : 3d遷移金属)を多数合成できることを明らかにした。これらは遷移金属原子の平均価電子数により結晶構造が擬正方晶から擬正方晶と立方晶の二相共存領域、そして立方晶へと変化する傾向にあることが判明した。さらに、擬正方晶構造領域においては、僅かに対称性の異なる3つの結晶構造が存在することを明らかにした。各結晶構造は3d電子の平均価電子数とサイズにより形成範囲が分布しており、遷移金属原子の平均価電子数と寸法因子が本系の結晶構造決定の主要因子であることを知見した。これらの結晶構造間には、遷移金属原子とゲルマニウム原子からなる配位多面体の連結様式の違いがあることが予測され、単結晶を育成し、結晶構造解析により構造移行の様式を解明することが今後の課題である。 磁気的性質の評価からこれらの化合物群では、狭い3dバンド内での電子間相互作用(電子相関)が結晶構造や物性に関わる重要な因子であることが明らかとなった。平均電子数に依存して、遍歴系の強磁性挙動を示すものから、磁気モーメントをもたないものまで、幅広く分布する物質群と位置づけられる。

  27. 組成傾斜化による広温度域高誘電導性材料の開発

    島田 昌彦, 滝沢 博胤, 窪田 俊一, 内田 聡, 山根 久典

    1996年 ~ 1996年

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    高誘電率セラミックスコンデンサーは、BaTiO_3に種々の添加物を均一に加えて、BaTiO_3が持つ相転移温度(120℃)付近の高誘電率ピークを室温付近に移動させ、その急激な誘電率の温度変化を小さくすることにより製造されている。本研究では、酸化物強誘電体の誘電率が相転移の際に増大することと、その相転移温度が固溶体の形成とその組成で移動することを利用し、固溶体組成の傾斜化により誘電率の温度変化そ調整することで、広範囲の温度領域で所望の温度係数を有する高誘電材料の開発を目標とした。 BaTiO_3-SrTiO_3固溶体では、粉末試料を積層し固相拡散によりBa-Srの組成傾斜化を試みた。BaTiO_3と(Ba_<0.5>Sr_<0.5>) TiO_3の積層試料間では、1450℃、15hの条件でわずかにBa-Srの相互拡散が認められた。SrTiO_3との組み合わせでは拡散が遅く、種々の組成傾斜分布を実現するためには、より高温での合成が必要と考えられる。K (Ta_<1-x>Nb_x) O_3傾斜固溶体の作製では、融液の非平衡冷却による方法を試みたところ、1mm程度の比較的大きな単結晶が得られた。これらの単結晶では、冷却過程に依存して内部から周辺部にっけてTaからNbへの組成傾斜がみられ、誘電率の温度依存性も組成分布に対応して変化した。この系では、冷却温度プログラムや融液などの作製条件と生成物の組成分布、誘電特性との関係を明らかにすることにより、様々な誘電特性を有する傾斜機能材料が作製できることが示された。

  28. 二次元空間における希土類錯体の創製と発光特性

    滝沢 博胤, 島田 昌彦

    1996年 ~ 1996年

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    「高輝度発光材料」を創製する目的から、これまで「希土類イオン」を付活した酸化物の結晶構造の次元性と高濃度付活における発光特性などとの関係について検討してきた。その結果、希土類イオンの高濃度付活による濃度消光を抑制するには、エネルギー伝達の遮蔽効果が必要であることを知見した。 "嵩高い"希土類錯体は、エネルギー的に有効な遮蔽効果をもつことを期待し、粘土鉱物の一つ"スメクタイト"に高い分極能をもつo-フェナイトロリンを配位子とした希土類錯体の吸着条件を検討し、錯体濃度に依存した配列状態や発光特性などについて調べ、配列状態の変化より、二次元層空間に閉じ込められた同種、あるいは異種希土類錯体間のエネルギー移動を新たに知見した。 モンモリロナイト層間へのインターカレーション反応により作製したMT-Eu, Tb (phen)^<3+>_2複合体の基本面間隔は、約18Åとなり、層間においてEu (phen)^<3+>_2とTb (phen)^<3+>_2の異種錯体が二分子層を形成し、互いに近接した立体配置をとることが判明した。Eu (phen)^<3+>_2吸着量に対するMT-Eu (phen)^<3+>_2およびMT-Eu, Tb (phen)^<3+>_2複合体におけるEu^<3+>の発光強度変化を比較した結果、同じEu (phen)^<3+>_2の吸着量においてMT-Eu, Tb (phen)^<3+>_2の発光強度が著しく増大し、吸着量に対する発光強度増加率も増大した。 これらの結果より、二次元空間においてTb (phen)^<3+>_2とEu (phen)^<3+>_2は、均一な溶媒や結晶構造中よりも近接した立体配置をとり、これがEu (phen)^<3+>_2に対するTb (phen)^<3+>_2の光増感作用を誘起することが明らかとなった。

  29. 希土類アルミン酸塩セラミックスの応力誘起相転移に関する研究

    島田 昌彦, 遠藤 忠, 滝沢 博胤, 内田 聡, 山根 久典

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:TOHOKU UNIVERSITY

    1995年 ~ 1996年

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    応力誘起相転移によるセラミックスの強靱化作用が期待できる新規酸化物セラミックス素材として、希土類アルミン酸塩、R_4Al_2O_9(R:Gd,Ho)に注目し、高温相を準安定化するための諸因子を実験的に探索し、R_4Al_2O_9とGd_4Al_2O_9/MgO複合セラミックスの緻密質焼結体を作製して熱的・機械的性質を評価し、応力誘起相転移による新しい強靱化セラミックス創製のための基礎的研究を行った。 1.1700℃で40時間焼結反応を行った焼結体の結晶相は、(Ho_<1-x>La_x)_4Al_2O_4ではX=0.2までは斜方晶単一相であり、X=0.2以上ではLaAlO_3が第2相として生成した。一方、(Gd_<1-x>La_x)_4Al_2O_4においては、X=0.4まで斜方晶単一相であり、X=0.4以上ではLaAlO_3が生成した。1400〜1600℃の焼結反応及び1700℃で5時間までの焼結反応で得られた試料は単斜晶相であった。 2.種々の粒径を有する単斜晶相試料を1700℃で5〜40時間熱処理し、得られた試料の結晶相と粒径の関係を評価した。その結果、一定粒径(臨界粒径)以上に粒成長すると、斜方晶相が準安定化し、希土類サイトをLaで置換することにより臨界粒径が小さくなることが判明した。(Ho_<1-x>La_x)_4Al_2O_4では、X=0での臨界粒径dc=6.2μm,X=0.2ではdc=3.3μmであった。 3.Gd_4Al_2O_9の相転移は温度ヒステレシスを持つ可逆的温度誘起相転移で、高温相から低温相へは0.4%の体積膨張を伴うマルテンサイト型相変態であることが判明した。 4.複合セラミックスの破壊強度は、高温からの降温時600℃で室温強度やGd_4Al_2O_9およびMgOより大きな破壊強度を有し、クラックヒーリング作用と同時に高温相から低温相への応力誘起相転移による変態強化機構が作用したものと考えられた。 本研究で、応力誘起相転移をする新しい希土類アルミン酸塩セラミックスを創製することが可能となったが、マルテンサイト型相転移の詳細な研究には高温中性子回析実験が課題である。

  30. 加圧焼結法による鉄シリサイド系高効率高温熱電変換材料の開発研究

    島田 昌彦, 今西 雄一郎, 遠藤 忠, 滝沢 博胤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (A)

    研究機関:TOHOKU UNIVERSITY

    1994年 ~ 1996年

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    鉄シリサイド系熱電変換素材に関するこれまでの研究成果を踏まえ、加圧焼結法により粒子形態・配向に異方的な微細構造を有するベータ型鉄ダイシリサイド系焼結体を作製し、熱電特性、エネルギー変換効率の異方性を評価するとともに、高効率化と実用化への指針を得るための基礎的研究を行った。 1.出発原料のFe,Ru,Si,Cr(P型),Co(n型)粉末を所定比秤量・混合後、シリカチューブを用いた真空封入法により1100℃、48時間焼成してα相とε相の混合相を合成した。続いて真空封入法で850℃、168時間の長時間アニールによりβ相を単一相として合成することが出来た。このようにして得られたβ相の粉末をBNカプセルに封入し、ベルト型超高圧発生装置で3.0GPa,800℃で30分高圧焼結反応を行って焼結体を作製した。加圧焼結法として、30MPa,800℃,5時間のホットプレス焼結反応によっても焼結体を作製し、超高圧焼結法で作製した試料との比較検討を行った。 2.加圧下での溶融・凝固法で得た焼結体は、高温相(α相)とFeSi(ε相)の混合相であった。しかし、得られた焼結体は緻密で、かつ、α相粒子は加圧軸に平行な粒子配向をした微細構造を有しており、長時間アニールによって、特異な粒子形態・配向を有するベータ相焼結体を作製する新しい焼成プロセスを見出したものと考えられる。 3.超高圧焼結法で作製したβ-Fe_<0.92>Ru_<0.05>Cr_<0.03>Si_2(P型)焼結体のゼ-ベック係数を1100Kまで測定した結果、加圧軸に対して垂直方法のゼ-ベック係数(α_x)は加圧軸に対して平行方向の値(α_z)より1.5培程大きく、約750Kで330μv/Kの値を有することが判明した。一方、電気伝導度は加圧軸に対して平行方向の値(σ_z)の方がやや高い値を示した。真空焼結体は上述したような異方性を示さず、熱電特性の異方性は高圧焼結法によって作製した焼結体だけに発現することが判明した。 4.加圧焼結法で粒子配向した焼結体を作製することで、性能指数を改善することが判明し、ホットプレス法によって工業材料化の可能性を明らかにすることができた。

  31. ガリウム酸亜鉛焼結体の作成と光・電気物性の研究

    遠藤 忠, 滝澤 博胤, 島田 昌彦

    1995年 ~ 1995年

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    近年情報・通信技術の発達に伴い、精緻な画像を提供する「ハイビジョン」、「大型かつ平面」画像表示装置の具現化などに、益々高輝度発光材料の開発が必要不可欠となっている。本研究では、電子線励起による「高輝度発光体」の開発のための材料設計、ならびに材料探索の指針を得ることを目的に、スピネル型構造からなる「ガリウム酸亜鉛(化学組成;ZnGa_2O_4)」を対象にした系統的研究を図った。更に、その焼結体を作成し、二次電子放出に最適な電気的特性に関する材料の最適化を図った。 ガリウム酸亜鉛は自己付活型発光体であるが、(1)スピネル構造のZnGa_2O_4において、4配位サイト、6配位サイトの各々をMg^<2+>、Cd^<2+>、Li^+及びAl^<+3>、In^<3+>、Cr^<3+>、Mn^<2+>などの元素で固溶置換できる可能性を温度や雰囲気の制御により検討した。また、格子欠陥に伴う熱平衡的検討も行った。(2)得られた試料については、粉末X線回析法による相同定、紫外-可視拡散スペクトルの測定を行うと共に、紫外線もしくは電子線励起による蛍光及びカソードルミネッセンススペクトル等の光学的評価に供した。さらに、(3)焼結体に関する緻密化条件を探るため、走査型電子顕微鏡観察、EPMA測定による局所的組成分析などを行った。加えて、交流及び直流法による電気抵抗の測定、ゼ-ベック効果、ホール効果の測定によって、伝導機構の解明を図った。 以上、発光の機構解明、電子線励起による発光材料の設計指針の構築、及び新しい残光性発光体としてのZnGa_2O_4スピネルの可能性を初めて明らかにした。

  32. 二次元空間における希土類錯体の創製と発光特性

    遠藤 忠, 滝澤 博胤, 島田 昌彦

    1995年 ~ 1995年

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    「嵩高い」大きさの配位子をもつ希土類錯体は、幾何学的に制限された無機層空間において特異な立体構造をとる。無機層状化合物、特に粘土鉱物における層間での吸着量と錯体の立体構造、その配列状態や凝集形態などの相関性を明らかにし、新しい形状・形態からなる錯体の創製の可能性を探ること。二次元層骨格表面にある元素やイオン(例えば酸化物イオン)と配位子のπ電子との静電的な相互作用、エネルギー移動や回遊などを介した発光特性に関して検討し、希土類錯体の配列状態、凝集形態の違いを利用した新しい有機・無機複合発光材料の創製に資することを目的とした。 本年度は、具体的には、(1)「o-フェナントロリンやビピリジル」を配位子としてた、Eu^<3+>以外の錯体の作製条件について検討した。その結果、ビス錯体においてEu^<3+>錯体とTb^<3+>錯体のように異種希土類イオンの錯体が層間において共存し、吸着できることを明らかにした。(2)得られた層間化合物について、粉末X線回折及び赤外線吸収スペクトル、ラマンススペクトルなどの分光学的手法を用いて、層間での希土類錯体の立体配置、配列状態を決定した。(3)可視・紫外線吸収スペクトル、ラマンスペクトルを組み合わせて、層間に吸着した希土類錯体の対称性の評価、励起・発光スペクトルを測定し、粘土層表面酸素との配位子とのπ-π相互作用、また、希土類イオン間のエネルギー移動や回遊などについて系統的に解析した。

  33. 二次元空間における希土類錯体の創製と発光特性

    遠藤 忠, 滝澤 博胤, 島田 昌彦

    1994年 ~ 1994年

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    無機材料の中には層状構造をとるものが少なくない。本研究では、結晶層と結晶層の、いわば二次元的な空間におかれた"嵩高い"大きさの希土類錯体について、吸着量と立体構造、配列状態や凝集形態などの相関性を明らかにし、新しい形状・形態からなる錯体の創製の可能性を探った。また、層骨格表面にある元素やイオンと配位子のπ電子との静電的な相互作用、エネルギー移動や回遊などを介した発光特性を調べ、新しい発光材料の設計に資することを目的とした。 (1)ハイドロタルサイト(HT)の層間を利用してEDTAやDTPAのEu^<3+>錯体の吸着できる可能性を検討した。次いで、(2)2,2'-ビピリジン[bpy]やトリス(1,10-フェナントロリン)[phcn]を配位子として希土類(Eu^<3+>)錯体を新たに作製し、これをスメクタイトなどの粘土層間に吸着して、"有機と無機"の複合化に伴う発光特性を評価し、表面酸素を介した希土類錯体間でのエネルギー移動や回遊について明らかにした。 得られた層間化合物については、粉末X線回折及び赤外線吸収スペクトル、ラマンスペクトルなどの現有する分光学的手法を用いて、層間での希土類錯体の立体配置、配列状態を決定した。可視・紫外線吸収スペクトル、ラマンスペクトルを組み合わせて、層間に吸着した希土類錯体の対称性の評価、励起・発光スペクトルを測定し、希土類錯体の濃度依存性などの結果から、粘土層表面酸素と配位子とのπ-π相互作用、また、希土類イオン間のエネルギー移動や回遊などについて系統的に解析した。

  34. 高次配向構造構築のための粘土層間反応に関する研究

    遠藤 忠, 滝澤 博胤, 島田 昌彦

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for General Scientific Research (B)

    研究機関:TOHOKU UNIVERSITY

    1993年 ~ 1994年

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    「ラングミュアー・ブロジェット膜」作製法を利用することによって,高次配向構造をもつ有機・無機ナノ複合体の合成できる可能性を,種々の有機分子などとの組み合わせから検討した。また,極限構造の構築によって光機能などの物性の設計できる可能性を探ることに関する,「ラングミュアー・ブロジェト膜」作製法は,インターカレーション法とは異なり,調製条件の設計・制御により,高次な極性構造をもつ有機・無機複合超組織薄膜を実現できるものである。無機物として粘土鉱物を対象に無機と有機との複合化に初めてラングミュアー・ブロジェット膜作製法の有効性を明らかにした。粘土の凝集状態の特異性や層構造の示す「水和膨潤性」を利用して,超音波による物理的撹拌などの操作により,(1)粘土の積層する二次元層骨格を完全にばらばらの状態に剥離し,純水中に分散させた下層溶液を作成,(2)この溶液表面にステアリルアミンなどの棒状単分子を広げ,次いでこれをバリアで圧縮し,疎水基を上部に向けた単分子膜を形成する。つまり,下層溶液の界面にはステアリルアミンの親水基が接し,ここに同溶液内に分散している粘土単位層が静電力によって吸着する形を実現する。(3)この状態で,有機物と無機物とがナノオーダーで積層し,かつこれを繰り返すと粘土とステアリルアミンとが数十層まで累積できることを世界で初めて明らかにした。

  35. 希土類賦活による高輝度発光材料の研究

    島田 昌彦, 遠藤 忠, 滝沢 博胤

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for General Scientific Research (B)

    研究機関:TOHOKU UNIVERSITY

    1993年 ~ 1994年

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    母結晶の次元性、特に層状構造に着目して二重Ta‐O層で隔てられた(La,Ta)‐O層からなるLaTa_7O_<19>を母結晶に選び、高輝度の青色、緑色および赤色蛍光体の材料開発の基礎的研究を行った。 1.出発原料としてLa_2O_3,Tm_2O_3,Tb_4O_7,Eu_2O_3とTa_2O_5(純度99.9%以上)を用い、(La_<1-x>R_x)Ta_7O_<19>(R=Tm,Tb,Eu)の組成式に秤量後12MHNO_3で溶解・蒸発乾固する硝酸塩共分解法により原料を調整し、空気中1200℃で24時間焼成して六方晶系の単一相固溶体を合成することに成功した。格子定数の組成依存性より、Tm^<3+>,Tb^<3+>とEu^<3+>はLa^<3+>サイトを仕込み組成通り完全固溶したことが判明した。 2.(La_<1-x>R_x)Ta_7O_<19>(R=Tm^<3+>,Tb^<3+>,Eu^<3+>)固溶体において、Tm^<3+>では460nm付近の青色発光、Tb^<3+>では547nm付近の緑色発光、Eu^<3+>では610nm付近の赤色発光がシャープな発光スペクトルとして観測できた。発光強度の組成依存性の結果より、最大発光強度となるXの値は、Tm^<3+>ではX=0.2,Tb^<3+>ではX=0.8,Eu^<3+>では濃度消光は起こらず、X=1.0のEuTa_7O_<19>試料が最も強い発光強度を有していることが判明した。三次元的結晶構造であるYAIO_3にTm^<3+>,Tb^<3+>,Eu^<3+>を付活した試料の最大発光強度となる組成はX=0.02〜0.04である結果と比較すると、本研究で得られた希土類固溶発光体は高濃度型高輝度発光体であることが判明した。 3.本研究で得られた希土類固溶体の発光減衰特性を評価した結果、発光減衰曲線は擬二次元的エネルギー回遊の式で解析できることが判明し、LaTa_7O_<19>母結晶の二次元層状構造を反映した優れた高濃度型高輝度発光体材料であることがわかった。本研究で得られた成果を基にして、電子線などの励起エネルギーを効率よく吸収し、発光中心となる希土類イオンなどにできるだけ速やかにエネルギー伝達できる機構をもつ新しい形の高輝度発光体の開発に関する基礎的研究成果が得られた。

  36. 高強度高イオン導電性立方晶ジルコニアセラミックス材料の開発研究

    島田 昌彦, 斎藤 哲夫, 滝沢 博胤, 遠藤 忠, 斉藤 哲夫

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Developmental Scientific Research (B)

    研究機関:TOHOKU UNIVERSITY

    1991年 ~ 1993年

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    イットリウム固溶立方晶ジルコニアセラミックスを平板型固体電解質型燃料電池の電解質として用いる場合、発電効率向上のための電解質の薄肉化、大型化のための大面積化、耐熱応力性の向上のため、高強度化と高靭性化が実用化のための大きな課題である。本研究では高イオン導電性を有する立方晶ジルコニアの導電率を保持しつつ、機械的特性を付与できる可能性を検討し、高強度高イオン導電性立方晶ジルコニアセラミックス材料開発の基礎的研究を行った。 1.Y_2O_3を2〜8モル%固溶したイットリウム固溶ジルコニアセラミックスについて検討を行い、正方晶と立方晶の存在割合と機械的性質およびイオン導電率の関係を明らかにした。強度が要求される電解質では、正方晶ジルコニア粒子分散立方晶ジルコニアの利用が有効であり、特に5モル%Y_2O_3-ZrO_2の破壊強度は525MPa,破壊靭性値は7.9MPam^<1/2>で、900℃のイオン導電率は0.05Scm^<-1>であった。 2.8モル%Y_2O_3固溶立方晶ジルコニアに5〜30体積%Al_2O_3粒子を分散した複合セラミックスにおいては、20体積%Al_2O_3粒子分散立方晶ジルコニアの破壊強度は355MPa,破壊靭性値は3.3MPam^<1/2>,900℃のイオン導電率は0.06Scm^<-1>であった。正方晶ジルコニアあるいはAl_2O_3粒子分散立方晶ジルコニアでは、イオン導電率はやや低下するが、機械的特性は約3倍となることが判明した。 3.イットリウムとスカンジウムを同時固溶した立方晶ジルコニアでは、8モル%Y_2O_3固溶立方晶ジルコニアに比べて、破壊強度とイオン導電率ともに大きく向上した。2モル%Y_2O_3-6モル%Sc_2O_3同時固溶立方晶ジルコニアの破壊強度は214MPa,900℃のイオン導電率は0.141Scm^<-1>で、平板型固体電解質として優れた素材であることが判明した。本研究を通して、異なる2つの機能を同時に満たすセラミックス材料開発の基礎的研究成果が得られた。

  37. ジルコニア粒子分散柱状・ワラストナイト焼結体の作製と機械的熱的性質の研究

    島田 昌彦, 滝沢 博胤, 遠藤 忠

    1992年 ~ 1992年

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    機械加工可能で高温でのセラミックス型材として材料開発が望まれているワラストナイト焼結体の高強度化と熱的安定性の向上を目的として、ジルコニア粒子分散ワラストナイト焼結体の作製を行なった。ゾノトライトに5-15体積%ジルコニア粉末を添加した混合粉末を空気中700℃-1150℃で5時間焼成し、ジルコニア分散βーワラストナイト複合体を、1200-1400℃焼成でジルコニア分散αーワラストナイト複合体を作製した。ジルコニア分散ワラストナイト複合体では、700-1100℃焼成で、針状、柱状、板状ワラストナイトがマトリックス相を形成し、1150℃の温度では、板状粒子は急激な粒子再配列によって緻密化した。1200-1400℃焼成では、焼結温度の上昇とともに等軸粒子の粒成長が顕著となった。分散ジルコニア粒子はワラストナイトマトリックス中の粒界に均質に分布し、ジルコニア粒子添加量の増加とともに、ワラストナイトの粒成長は抑制された。ワラストナイト単味の破壊強度は30MPaと低強度であるが、ジルコニア分散によって高強度化し、5体積%ジルコニア分散βーワラストナイト複合体で、150MPaと5倍向上し、15体積%ジルコニア分散αーワラストナイト複合体では80MPaとなった。このような強度向上は、ジルコニア粒子分散によるマトリックス粒子の微細化と相転移強化機構によるものと考えられる。ビッカス硬度はジルコニア添加によってもほぼ一定値を示した。ジルコニア分散ワラストナイトの熱衝撃抵抗は、ハッセルマンの熱応力破壊モデルにおける初期亀裂の大きいモデルに適合し、大きなサイズの空孔が熱応力破壊源となることが判明した。ジルコニア添加量が増加すると、マトリックス粒子は微細化し、その結果として耐熱衝撃性が向上し、600℃の温度差でも約30MPaの強度を有し、ジルコニア無添加のワラストナイト単味焼結体と同程度の破壊強度となり、ワラストナイトへのジルコニア添加は有効であった。

  38. 周期律化合物の超高圧合成と光・電気的性質

    遠藤 忠, 滝沢 博胤, 島田 昌彦

    1992年 ~ 1992年

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    IV族元素と等電子構造を有し、IV族に対して非対称に位置する元素からなる三元系化合物(周期律化合物)の中で、閃亜鉛鉱類似型構造のZnSiP_2やZnGeP_2、歪ウルツ鉱型構造の新しい物質、ZnSiN_2及びZnGeN_2の合成できることを明らかにし、本年度はその固溶体、ZnSi_1- ^XGe_XN_2について合成を行い、併せてその光学的性質を調べた。 ベルト型高圧装置を用いて、5〜8GPa、800〜1600℃の条件下で、1〜3時間合成を行った試料について、粉末X線回折法による相同定を行った結果、ZnSi_1- ^XGe_XN_2はMnSiN_2と同形で斜方晶系に帰属されることがわかった。更に、ZnSi_1- ^XGe_XN_2固溶体の光学的バンドギャップは、Ge濃度の増加とともに単調に減少することがわかった。これより、全組成域にわたって直接型光学遷移がバンド端間で生じているものと考えられた。 また、直接遷移型のワイドバンドギャップ半導体であることから、発光体としての可能性を探る目的で、ZnSiN_2のZn^<2+>を一部Mn^<2+>を一部Mn^<2+>で置換することを試みた。6.0GPa,1300-1500℃の条件下で処理することにより、単一相として新しく固溶体(化学組成;Mn_XZn_1- ^XSiN_<(2-2/3X)>0_X)が得られた。これは、ZnSiN_2と同形の歪ウルツ鉱型構造として指数付けでき、ZnとMnとが全域固溶することを見いだした。この固溶体の励起及び発光スペクトルから、600nm付近のピークの相対強度は、Xに依存しており、濃度消光を示すことを見いだした。また、その波長からはMnの価数は2+とみなされた。一方、640nm付近のピークは全ての濃度域において存在し、Xの濃度にも依存することからZnSiN_2に帰属されるものと考えられた。

  39. 希土類賦活によるペロブスカイト型化合物の合成と蛍光特性

    遠藤 忠, 滝沢 博胤, 島田 昌彦

    1991年 ~ 1991年

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    岩塩型のSrO層とペロブスカイト型のSrSnO_3層とが組み合わさった層状ペロブスカイト型構造のSrx_<+1>SnxO_3x_<+1>について、Eu^<2+>イオンを賦活した蛍光体を合成し、構造の特徴である次元性、あるいはEu^<2+>イオンの分布などが蛍光特性に及ぼす影響について系統的に検討することを目的とした。 合成実験は、SrCO_3とEu_2O_3とを所定比に秤量してアルゴンガス中1500℃、3時間で焼成後、SnO_2を加えて、アルゴンガス中1300ー1500℃、3時間の条件で行なわれ、(Sr_<1ー>yEuy)x_<+1>SnxO_3x_<+1>を合成した。得られた試料は、X=1,2,3の相として同定されたが、Eu^<2+>イオンが賦活された系として再現良く得られたのはX=1,2であった。拡散反射スペクトルの測定結果から、SrSnO_3,Sr_2SnO_4およびSr_3Sn_2O_7は、各々約4.27eV,4.95eVおよび5.06eVに吸収端をもつことがわかった。蛍光スペクトルの測定結果から、K_2NiF_4型構造の(Sr_<1ー>xEux)_2SnO_4は、400ー500nmにわたる幅広いスペクトルを示したが、Sr_<1->xEuxSnO_3や(Sr_<1->xEux)_3Sn_2O_7では、確認できる蛍光は観測されなかった。 歪みペロブスカイト型構造のYA10_3にCe^<3+>,Tm^<3+>,Pr^<3+>の各イオンを賦活し、結晶場の対称性が蛍光スペクトルに与える影響について調べるために、Tm^<3+>やPr^<3+>系では、大気中1500ー1700℃で、Ce^<3+>系では、アルゴン雰囲気下、1500℃で焼成し試料を得た。得られた試料はいずれも所定の単一相であった。(Y_<0.99>Ce_<0.01>)A10_3における励起、及び発光スペクトルを測定した結果、いづれもブロ-ドでCe^<3+>の4f→5d遷移に帰属されるものであることがわかった。一方、Tm^<3+>,Pr^<3+>を賦活したものは、各イオン濃度X=0.01付近で蛍光強度の最大となる濃度消光が顕著に現われた。こうした結果を踏まえて、YA10_3では、三次元的なエネルギ-回遊の起こっているものと考えられ、高濃度賦活を行なうには、K_2NiF_4型構造のように母結晶の次元性が重要であると考えるに至った。

  40. 周期律化合物の超高圧合成と光・電気的性質

    遠藤 忠, 滝沢 博胤, 島田 昌彦

    1991年 ~ 1991年

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    本年度は窒素を含むIIーIVーV_2族「周期律化合物」の中で、ウルツ鉱型構造を有する新しい化合物の合成できる可能性を調べた。その結果、新たにZnSiN_2に加えZnGeN_2やその個溶体ZnSi_1ーxGexN_2の合成できることを明らかにしたので、その光学的あるいは電気的性質とを併せ報告した。Zn_3N_2とSi_3N_4(またはGe_3N_4)粉末とを所定比に秤量、hBN(窒化ほう素)カプセルへ充填し、1.5ー7.7GPa,600ー1800℃,0.5ー3.0hrの条件下で処理した後,急冷操作によって試料を得た。Zn_3N_2とSi_3N_4とを6.0GPa,1500℃,3hrの条下で処理し、得られた白色粉末試料は,新しい化合物ZnSiN_2であり歪みウルツ鉱型構造をもつことがわかった。6.0GPa,1000℃,3hrの条件下でZn_3N_2とGe_3N_4とを反応させた結果、黄色粉末試料が得られ、ZnGeN_2はZnSiN_2と同形の斜方晶系に属する化合物であることが粉末x線回折図形からわかった。次いで、固溶体ZnSi_1ーxGexN_2を1.5ー5.7GPa,800ー1500℃の条件下で合成した。いずれも単一相で得られることを、粉末x線回折図形より確認した。Geの固溶量の増加に伴って、単調に格子定数や単位格子体積の増加することがわかった。空間群Pna2_1のSiサイトをGeが置換するとしてリ-トフェルト解析を行なった結果、いずれもR因子は8%以下になることがわかった。拡散反射スペクトルから求めたバンドギャップの大きさは、Geの固溶量の増加に伴って単調に減少することがわかった。従ってSiーGe混晶系のものとは異なり、直接型光学遷移がバンド端間で起きているものと考えることができた。ESCAスペクトルから、Si(or Ge)_3N_4やZn_3N_2に比べてZnSi(or Ge)N_2では、Si(2p)、Ge(3d)やN(1s)のスペクトルが、いずれも低エネルギ-側にシフトし、Zn(2p_<3/2>)のスペクトルが高エネルギ-側にシフトすることが明らかになった。

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社会貢献活動 1

  1. 日本高圧力学会評議員

    2002年9月 ~ 2004年9月