Details of the Researcher

PHOTO

Kazuaki Kawahara
Section
Institute for Materials Research
Job title
Associate Professor
e-Rad No.
90869570

Research History 5

  • 2026/01 - Present
    Tohoku University　Institute for Materials Research

  • 2020/08 - 2025/12
    The University of Tokyo　The Graduate School of Engineering Institute of Engineering Innovation　Assistant professor

  • 2017/06 - 2020/07
    The University of Tokyo　The Graduate School of Engineering Institute of Engineering Innovation　Postdoctoral researcher

  • 2017/04 - 2017/05
    The University of Tokyo　Graduate School of Frontier Sciences　Postdoctoral researcher

  • 2015/04 - 2017/03
    The University of Tokyo　Graduate School of Frontier Sciences　JSPS research fellow

Education 2

  • The University of Tokyo　Graduate School of Frontier Sciences　Department of Advanced Materials Science

    2012/04 - 2017/03

  • The University of Tokyo　The Faculty of Engineering　Department of Applied Chemistry

    2008/04 - 2012/03

Professional Memberships 4

  • 日本顕微鏡学会

    2023/02 - Present

  • The Ceramic Society of Japan

    2018/09 - Present

  • The Japan Society of Vacuum and Surface Science

    2015/10 - Present

  • The Physical Society of Japan

    2013/08 - Present

Research Interests 2

  • Lithium ion battery

  • Fluoride ion battery

Research Areas 1

  • Nanotechnology/Materials / Structural and functional materials /

Awards 5

  1. 優秀発表賞

    2017/09　第17回結晶界面工学研究会　Application of Markov chain Monte Carlo method to curve fitting

  2. JSPS HOPE Fellow

    2016/03　日本学術振興会　Structure of silicene grown on Ag(111)

  3. Student Prize

    2014/12　表面界面スペクトロスコピー　Ag(111) 上に成長させたシリセンの構造

  4. 修士論文優秀賞

    2014/03　東京大学新領域創成科学研究科物質系専攻　Ag(111)上に成長させたシリセンの構造

  5. 新領域創成科学研究科長賞

    2014/03　東京大学　Ag(111)上に成長させたシリセンの構造

Papers 39

  1. Structural transition and the effect of Ca impurities in MgO Σ5(210) grain boundary Peer-reviewed

    Qian Chen, Mitsuhiro Saito, Kazuaki Kawahara, Atsutomo Nakamura, Kazutoshi Inoue, Yuichi Ikuhara

    Journal of the European Ceramic Society　46　(6)　118068-118068　2026/06

    Publisher: Elsevier BV

    DOI： 10.1016/j.jeurceramsoc.2025.118068 　

    ISSN： 0955-2219

  2. 3D dynamic structure of a Pt nanoparticle on SrTiO3 (001) during in-situ heating atomic-resolution ADF STEM imaging Peer-reviewed

    Ryo Ishikawa, Rikuto Kubota, Kazuaki Kawahara, Toshihiro Futazuka, Yuichi Ikuhara, Naoya Shibata

    Nature Communications　17　(1)　2026/02/27

    Publisher: Springer Science and Business Media LLC

    DOI： 10.1038/s41467-026-69767-5 　

    eISSN： 2041-1723

  3. LaCu5 intermetallic alloy cathode for fluoride-ion batteries Peer-reviewed

    Shun Sasano, Ryo Ishikawa, Kazuaki Kawahara, Naoya Shibata, Yuichi Ikuhara

    Journal of Power Sources　658　238294-238294　2025/12

    Publisher: Elsevier BV

    DOI： 10.1016/j.jpowsour.2025.238294 　

    ISSN： 0378-7753

  4. Dopant diffusion and segregation of iron in a near 45° (100) twist grain boundary in SrTiO 3 Peer-reviewed

    William Hahn, Kazuaki Kawahara, Shun Sasano, Bin Feng, Naoya Shibata, Yuichi Ikuhara, Klaus van Benthem

    Journal of the American Ceramic Society　109　(1)　2025/10/24

    Publisher: Wiley

    DOI： 10.1111/jace.70312 　

    ISSN： 0002-7820

    eISSN： 1551-2916

    More details Close

    Abstract Dopant segregation is a key contributor to interfacial stability and the macroscopic physical properties of polycrystalline materials. Near 45° (100) twist grain boundaries were diffusion bonded either from Fe‐doped SrTiO 3 single crystals, or nominally undoped single crystals after a thin film of iron was deposited onto the single crystal surface prior to diffusion bonding. After diffusion bonding, scanning transmission electron microscopy characterization detected increased Fe signals from the grain boundary cores of both types of bicrystals. Fe enrichment occurred either by segregation from the doped single crystals or by dopant out‐diffusion into the bulk away from the deposited layer. Quantitative energy dispersive X‐ray spectroscopy experiments identified that the grain boundary prepared after Fe deposition was characterized by much higher dopant enrichment compared to the case after diffusion bonding of two doped single crystals. Additional thermal annealing of the bicrystal formed after iron layer deposition caused a decrease in iron enrichment approaching the excess observed for the diffusion‐bonded doped single crystals. The experimental results demonstrate that, dependent on the method of doping, extended thermal annealing of bicrystals may be necessary after diffusion bonding to achieve equilibrium grain boundary excess quantities.

  5. Three-dimensional Deconvolution for Large-angle Illumination ADF-STEM Depth Sectioning Peer-reviewed

    Taichi Kusumi, Hajime Ueda, Toshiro Futazuka, Masatoshi Hanai, Shun Katakami, Kazuaki Kawahara, Ryo Ishikawa, Naoya Shibata, Masato Okada

    Microscopy and Microanalysis　31　(Supplement_1)　2025/07/25

    Publisher: Oxford University Press (OUP)

    DOI： 10.1093/mam/ozaf048.712 　

    ISSN： 1431-9276

    eISSN： 1435-8115

  6. Capacity enhancement of LaAl2Ag ternary alloy anode for fluoride-ion batteries Peer-reviewed

    Shun Sasano, Ryo Ishikawa, Kazuaki Kawahara, Naoya Shibata, Yuichi Ikuhara

    Journal of Materials Chemistry A　13　(24)　18610-18617　2025/05

    Publisher: Royal Society of Chemistry (RSC)

    DOI： 10.1039/d5ta00837a 　

    ISSN： 2050-7488

    eISSN： 2050-7496

    More details Close

    We demonstrate the LaAl2Ag ternary alloy as a new anode for fluoride-ion batteries. Compared to pure Al metal and LaAl3 binary alloy anodes, the LaAl2Ag anode shows a high reversible capacity of more than 400 mA h g−1 with good cycle stability.

  7. La1−xSrxF3−x: A Solid-State Electrolyte for Fluoride Ion Battery with High Ionic Conductivity and Wide Electrochemical Potential Window Peer-reviewed

    Kazuaki Kawahara, Ryo Ishikawa, Shun Sasano, Naoya Shibata, Yuichi Ikuhara

    Journal of The Electrochemical Society　171　(11)　110508-110508　2024/11/01

    Publisher: The Electrochemical Society

    DOI： 10.1149/1945-7111/ad8d10 　

    ISSN： 0013-4651

    eISSN： 1945-7111

    More details Close

    Fluoride ion conductors are developed for use as solid-state electrolytes in fluoride ion batteries which are one of promising candidates for next-generation storage batteries. Ba-doped LaF3 (La0.9Ba0.1F2.9: LBF) is mainly used as a solid-state electrolyte in fluoride ion batteries. However, room temperature conductivity of LBF is considerably low, on the order of 10−6 S cm−1 and it is still unclear the optimal elements to be doped to LaF3. In this study, we have explored La0.9Sr x Ba0.1−x F2.9 system (x = 0, 0.01, 0.025, 0.05, 0.1), in which Ba in LBF is substituted for Sr and investigated the composition dependence of ionic conductivity. We elucidate that the higher concentration of Sr without Ba can significantly improve the ionic conductivity, and the maximum ionic conductivity of La0.9Sr0.1F2.9 is 1.5 × 10−5 S cm−1 at room temperature, which is one order of magnitude larger than that of LBF. The higher ionic conductivity of LSF is due to the larger grain size and higher sintering density of LSF compared to LBF, which results in lower grain boundary resistance. The LSF total ionic conductivity of 10−4 S cm−1 can be achieved at 350 K, which significantly lowers operating temperature of fluoride ion batteries down to 350 K.

  8. Highly Reversible Conversion‐Type CoSn2 Cathode for Fluoride‐Ion Batteries Peer-reviewed

    Shun Sasano, Ryo Ishikawa, Kazuaki Kawahara, Naoya Shibata, Yuichi Ikuhara

    Small　21　(1)　2024/10/22

    Publisher: Wiley

    DOI： 10.1002/smll.202408023 　

    ISSN： 1613-6810

    eISSN： 1613-6829

  9. New Poisson denoising method for pulse-count STEM imaging Peer-reviewed

    Taichi Kusumi, Shun Katakami, Ryo Ishikawa, Kazuaki Kawahara, Tiarnan Mullarkey, Julie Marie Bekkevold, Jonathan J.P. Peters, Lewys Jones, Naoya Shibata, Masato Okada

    Ultramicroscopy　264　113996-113996　2024/10

    Publisher: Elsevier BV

    DOI： 10.1016/j.ultramic.2024.113996 　

    ISSN： 0304-3991

  10. Real-time Denoising Algorithm for STEM Imaging Using Markov Random Field Model Peer-reviewed

    Taichi Kusumi, Shun Katakami, Ryo Ishikawa, Kazuaki Kawahara, Naoya Shibata, Masato Okada

    Microscopy and Microanalysis　30　(Supplement_1)　2024/07/24

    Publisher: Oxford University Press (OUP)

    DOI： 10.1093/mam/ozae044.214 　

    ISSN： 1431-9276

    eISSN： 1435-8115

  11. Total third-degree variation for noise reduction in atomic-resolution STEM images Peer-reviewed

    Kazuaki Kawahara, Ryo Ishikawa, Shun Sasano, Naoya Shibata, Yuichi Ikuhara

    Microscopy　74　(1)　1-9　2024/07/02

    Publisher: Oxford University Press (OUP)

    DOI： 10.1093/jmicro/dfae031 　

    ISSN： 2050-5698

    eISSN： 2050-5701

    More details Close

    Abstract Scanning Transmission Electron Microscopy (STEM) enables direct determination of atomic arrangements in materials and devices. However, materials such as battery components are weak for electron beam irradiation, and low electron doses are required to prevent beam-induced damages. Noise removal is thus essential for precise structural analysis of electron-beam-sensitive materials at atomic resolution. Total square variation (TSV) regularization is an algorithm that exhibits high noise removal performance. However, the use of the TSV regularization term leads to significant image blurring and intensity reduction. To address these problems, we here propose a new approach adopting L2 norm regularization based on higher-order total variation. An atomic-resolution STEM image can be approximated as a set of smooth curves represented by quadratic functions. Since the third-degree derivative of any quadratic function is 0, total third-degree variation (TTDV) is suitable for a regularization term. The application of TTDV for denoising the atomic-resolution STEM image of CaF2 observed along the [001] zone axis is shown, where we can clearly see the Ca and F atomic columns without compromising image quality.

  12. Real-time tracking of three-dimensional atomic dynamics of Pt trimer on TiO 2 (110) Peer-reviewed

    Ryo Ishikawa, Toshihiro Futazuka, Yu Jimbo, Kazuaki Kawahara, Naoya Shibata, Yuichi Ikuhara

    Science Advances　2024/03

    DOI： 10.1126/sciadv.adk6501 　

  13. La-Al Intermetallic Alloy Anode for Realizing High-Energy Fluoride-Ion Battery Peer-reviewed

    Shun Sasano, Ryo Ishikawa, Kazuaki Kawahara, Naoya Shibata, Yuichi Ikuhara

    Journal of The Electrochemical Society　170　120523-120523　2023/12/01

    DOI： 10.1149/1945-7111/ad136e 　

  14. Fast reconstruction of scanning transmission electron microscopy images using Markov random field model Peer-reviewed

    Taichi Kusumi, Shun Katakami, Ryo Ishikawa, Kazuaki Kawahara, Naoya Shibata, Masato Okada

    Ultramicroscopy　253　113811-113811　2023/11

    Publisher: Elsevier BV

    DOI： 10.1016/j.ultramic.2023.113811 　

    ISSN： 0304-3991

  15. Fluoride Ion Conductivity of Rb Doped KSbF4 Peer-reviewed

    Kazuaki Kawahara, Ryo Ishikawa, Naoya Shibata, Yuichi Ikuhara

    Journal of The Electrochemical Society　170　020528　2023/02/16

    Publisher: The Electrochemical Society

    DOI： 10.1149/1945-7111/acbca5 　

    ISSN： 0013-4651

    eISSN： 1945-7111

    More details Close

    Abstract All solid-state fluoride ion batteries are considered to be high energy density and safe energy storage devices. However, the F– ion conductivities of solid electrolytes at room temperature are low (< 10-6 S cm-1), which requires the higher operating temperature of fluoride ion battery such as 420 K or higher. Therefore, the faster F– ion conductors is strongly desired to operate fluoride ion battery at lower or even room temperature. KSbF4 is one of the promising candidates to have a faster F– ion conductivity. To expand F– ion conduction pathways, we doped Rb in KSbF4 and further investigated the compositional dependence of ionic conductivity in K1-xRbxSbF4 system. We found that ionic conductivity strongly depends on the chemical composition and conductivity was maximized at x = 0.15. At room temperature, the F– ion conductivity in the bulk and at the grain boundary of K0.85Rb0.15SbF4 were σbulk = 1.01 × 10-4 S cm-1 and σGB = 4.80 × 10-5 S cm-1, respectively.

  16. Formation of La-rich tysonite nano-precipitates in fluorite Ba0.6La0.4F2.4 Peer-reviewed

    Shun Sasano, Ryo Ishikawa, Kazuaki Kawahara, Atsushi Mineshige, Naoya Shibata, Yuichi Ikuhara

    Journal of Power Sources　557　232581-232581　2023/02

    Publisher: Elsevier BV

    DOI： 10.1016/j.jpowsour.2022.232581 　

    ISSN： 0378-7753

  17. Atomic-resolution STEM image denoising by total variation regularization Peer-reviewed

    Kazuaki Kawahara, Ryo Ishikawa, Shun Sasano, Naoya Shibata, Yuichi Ikuhara

    Microscopy　71　(5)　302-310　2022/06/17

    Publisher: Oxford University Press (OUP)

    DOI： 10.1093/jmicro/dfac032 　

    ISSN： 2050-5698

    eISSN： 2050-5701

    More details Close

    Abstract Atomic-resolution electron microscopy imaging of solid-state material is a powerful method for structural analysis. Scanning transmission electron microscopy (STEM) is one of the actively used techniques to directly observe atoms in materials. However, some materials are easily damaged by the electron beam irradiation, and only noisy images are available when we decrease the electron dose to avoid beam damages. Therefore, a denoising process is necessary for precise structural analysis in low-dose STEM. In this study, we propose total variation (TV) denoising algorithm to remove quantum noise in an STEM image. We defined an entropy of STEM image that corresponds to the image contrast to determine a hyperparameter and we found that there is a hyperparameter that maximizes the entropy. We acquired atomic-resolution STEM image of CaF2 viewed along the [001] direction and executed TV denoising. The atomic columns of Ca and F are clearly visualized by the TV denoising, and atomic positions of Ca and F are determined with the error of ±1 pm and ±4 pm, respectively.

  18. Lithium Lanthanum Titanate Single Crystals: Dependence of Lithium-Ion Conductivity on Crystal Domain Orientation Peer-reviewed

    Shunsuke Kobayashi, Daisaku Yokoe, Yasuyuki Fujiwara, Kazuaki Kawahara, Yuichi Ikuhara, Akihide Kuwabara

    Nano Letters　2022/06/13

    Publisher: American Chemical Society (ACS)

    DOI： 10.1021/acs.nanolett.2c01655 　

    ISSN： 1530-6984

    eISSN： 1530-6992

  19. Atomic-Level Changes during Electrochemical Cycling of Oriented LiMn2O4 Cathodic Thin Films Peer-reviewed

    Yumi H. Ikuhara, Xiang Gao, Kazuaki Kawahara, Craig A. J. Fisher, Akihide Kuwabara, Ryo Ishikawa, Hiroki Moriwake, Yuichi Ikuhara

    ACS Applied Materials & Interfaces　14　(5)　6507-6517　2022/02/09

    DOI： 10.1021/acsami.1c18630 　

    ISSN： 1944-8244

    eISSN： 1944-8252

  20. Anomalous dewetting growth of Si on Ag(111) Peer-reviewed

    Naoya Kawakami, Ryuichi Arafune, Emi Minamitani, Kazuaki Kawahara, Noriaki Takagi, Chun-Liang Lin

    Nanoscale　2022

    Publisher: Royal Society of Chemistry (RSC)

    DOI： 10.1039/d2nr03409c 　

    ISSN： 2040-3364

    eISSN： 2040-3372

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    We demonstrate the novel growth of silicene grown on Ag(111) using STM and reveal the mechanism with KMC simulation.

  21. Arrangement of polyhedral units for [0001]-symmetrical tilt grain boundaries in zinc oxide Peer-reviewed

    Kazutoshi Inoue, Ji-Young Roh, Kazuaki Kawahara, Mitsuhiro Saito, Motoko Kotani, Yuichi Ikuhara

    Acta Materialia　212　116864-116864　2021/06

    Publisher: Elsevier BV

    DOI： 10.1016/j.actamat.2021.116864 　

    ISSN： 1359-6454

  22. Atomic-Resolution Topographic Imaging of Crystal Surfaces Peer-reviewed

    Ryo Ishikawa, Riku Tanaka, Kazuaki Kawahara, Naoya Shibata, Yuichi Ikuhara

    ACS Nano　15　(5)　9186-9193　2021/05/25

    Publisher: American Chemical Society (ACS)

    DOI： 10.1021/acsnano.1c02907 　

    ISSN： 1936-0851

    eISSN： 1936-086X

  23. Room temperature fluoride ion conductivity in defective β-KSb1-δF4-3δ polycrystals Peer-reviewed

    Kazuaki Kawahara, Ryo Ishikawa, Kei Nakayama, Naoya Shibata, Yuichi Ikuhara

    Journal of Power Sources　483　229173-229173　2021/01

    Publisher: Elsevier BV

    DOI： 10.1016/j.jpowsour.2020.229173 　

    ISSN： 0378-7753

  24. 3D arrangement of atomic polyhedra in tilt grain boundaries Peer-reviewed

    Kazutoshi Inoue, Kazuaki Kawahara, Mitsuhiro Saito, Motoko Kotani, Yuichi Ikuhara

    Acta Materialia　202　266-276　2020/10

    Publisher: Elsevier BV

    DOI： 10.1016/j.actamat.2020.10.017 　

    ISSN： 1359-6454

  25. Grain boundary Li-ion conductivity in (Li0.33La0.56)TiO3 polycrystal Peer-reviewed

    Shun Sasano, Ryo Ishikawa, Kazuaki Kawahara, Teiichi Kimura, Yumi H. Ikuhara, Naoya Shibata, Yuichi Ikuhara

    Applied Physics Letters　116　(4)　043901-043901　2020/01/27

    DOI： 10.1063/1.5141396 　

    ISSN： 0003-6951

    eISSN： 1077-3118

  26. Mechanically Tunable Spontaneous Vertical Charge Redistribution in Few-Layer WTe2 Peer-reviewed

    Zeyuan Ni, Emi Minamitani, Kazuaki Kawahara, Ryuichi Arafune, Chun-Liang Lin, Noriaki Takagi, Satoshi Watanabe

    The Journal of Physical Chemistry C　124　(3)　2008-2012　2020/01/23

    Publisher: American Chemical Society (ACS)

    DOI： 10.1021/acs.jpcc.9b10423 　

    ISSN： 1932-7447

    eISSN： 1932-7455

  27. Fast Li-ion conduction at grain boundaries in (La,Li)NbO3 polycrystals Peer-reviewed

    Kazuaki Kawahara, Ryo Ishikawa, Kei Nakayama, Takuma Higashi, Teiichi Kimura, Yumi H. Ikuhara, Naoya Shibata, Yuichi Ikuhara

    Journal of Power Sources　441　227187-227187　2019/11

    Publisher: Elsevier BV

    DOI： 10.1016/j.jpowsour.2019.227187 　

    ISSN： 0378-7753

  28. Unique fitting of electrochemical impedance spectra by random walk Metropolis Hastings algorithm Peer-reviewed

    Kazuaki Kawahara, Ryo Ishikawa, Takuma Higashi, Teiichi Kimura, Yumi H. Ikuhara, Naoya Shibata, Yuichi Ikuhara

    Journal of Power Sources　403　184-191　2018/11

    Publisher: Elsevier BV

    DOI： 10.1016/j.jpowsour.2018.09.091 　

    ISSN： 0378-7753

  29. Visualizing Type-II Weyl Points in Tungsten Ditelluride by Quasiparticle Interference Peer-reviewed

    Chun-Liang Lin, Ryuichi Arafune, Ro-Ya Liu, Masato Yoshimura, Baojie Feng, Kazuaki Kawahara, Zeyuan Ni, Emi Minamitani, Satoshi Watanabe, Youguo Shi, Maki Kawai, Tai-Chang Chiang, Iwao Matsuda, Noriaki Takagi

    ACS Nano　11　(11)　11459-11465　2017/11/28

    DOI： 10.1021/acsnano.7b06179 　

    ISSN： 1936-0851

    eISSN： 1936-086X

  30. Structural evolution of Bi thin films on Au(111) revealed by scanning tunneling microscopy Peer-reviewed

    Naoya Kawakami, Chun-Liang Lin, Kazuaki Kawahara, Maki Kawai, Ryuichi Arafune, Noriaki Takagi

    Physical Review B　96　(20)　2017/11/01

    DOI： 10.1103/physrevb.96.205402 　

    ISSN： 2469-9950

    eISSN： 2469-9969

  31. Surface structure of novel semimetal WTe2 Peer-reviewed

    Kazuaki Kawahara, Zeyuan Ni, Ryuichi Arafune, Tetsuroh Shirasawa, Chun-Liang Lin, Emi Minamitani, Satoshi Watanabe, Maki Kawai, Noriaki Takagi

    Applied Physics Express　10　(4)　045702-045702　2017/04/01

    DOI： 10.7567/apex.10.045702 　

    ISSN： 1882-0778

    eISSN： 1882-0786

  32. Atomic structure of “multilayer silicene” grown on Ag(111): Dynamical low energy electron diffraction analysis Peer-reviewed

    Kazuaki Kawahara, Tetsuroh Shirasawa, Chun-Liang Lin, Ryo Nagao, Noriyuki Tsukahara, Toshio Takahashi, Ryuichi Arafune, Maki Kawai, Noriaki Takagi

    Surface Science　651　70-75　2016/09

    DOI： 10.1016/j.susc.2016.03.029 　

    ISSN： 0039-6028

    eISSN： 1879-2758

  33. Spectroscopic Identification of Ag-Terminated “Multilayer Silicene” Grown on Ag(111) Peer-reviewed

    Chun-Liang Lin, Takeshi Hagino, Yujiro Ito, Kazuaki Kawahara, Ryo Nagao, Masaru Aoki, Shigeru Masuda, Ryuichi Arafune, Maki Kawai, Noriaki Takagi

    The Journal of Physical Chemistry C　120　(12)　6689-6693　2016/03/31

    DOI： 10.1021/acs.jpcc.6b00717 　

    ISSN： 1932-7447

    eISSN： 1932-7455

  34. Silicene on Ag(111): Geometric and electronic structures of a new honeycomb material of Si Peer-reviewed

    Noriaki Takagi, Chun-Liang Lin, Kazuaki Kawahara, Emi Minamitani, Noriyuki Tsukahara, Maki Kawai, Ryuichi Arafune

    Progress in Surface Science　90　(1)　1-20　2015/02

    DOI： 10.1016/j.progsurf.2014.10.001 　

    ISSN： 0079-6816

  35. Pragmatic Application of Abstract Algebra to Two-Dimensional Lattice Matching Peer-reviewed

    Kazuaki Kawahara, Ryuichi Arafune, Maki Kawai, Noriaki Takagi

    e-Journal of Surface Science and Nanotechnology　13　(0)　361-365　2015

    DOI： 10.1380/ejssnt.2015.361 　

    ISSN： 1348-0391

    eISSN： 1348-0391

  36. Determination of atomic positions in silicene on Ag(111) by low-energy electron diffraction Peer-reviewed

    K. Kawahara, T. Shirasawa, R. Arafune, C.-L. Lin, T. Takahashi, M. Kawai, N. Takagi

    Surface Science　623　25-28　2014/05

    DOI： 10.1016/j.susc.2013.12.013 　

    ISSN： 0039-6028

    eISSN： 1879-2758

  37. Substrate-Induced Symmetry Breaking in Silicene Peer-reviewed

    Chun-Liang Lin, Ryuichi Arafune, Kazuaki Kawahara, Mao Kanno, Noriyuki Tsukahara, Emi Minamitani, Yousoo Kim, Maki Kawai, Noriaki Takagi

    Physical Review Letters　110　(7)　2013/02/11

    DOI： 10.1103/physrevlett.110.076801 　

    ISSN： 0031-9007

    eISSN： 1079-7114

  38. Structural transition of silicene on Ag(111) Peer-reviewed

    Ryuichi Arafune, Chun-Liang Lin, Kazuaki Kawahara, Noriyuki Tsukahara, Emi Minamitani, Yousoo Kim, Noriaki Takagi, Maki Kawai

    Surface Science　608　297-300　2013/02

    DOI： 10.1016/j.susc.2012.10.022 　

    ISSN： 0039-6028

  39. Structure of Silicene Grown on Ag(111) Peer-reviewed

    Chun-Liang Lin, Ryuichi Arafune, Kazuaki Kawahara, Noriyuki Tsukahara, Emi Minamitani, Yousoo Kim, Noriaki Takagi, Maki Kawai

    Applied Physics Express　5　(4)　045802-045802　2012/03/28

    DOI： 10.1143/apex.5.045802 　

    ISSN： 1882-0778

    eISSN： 1882-0786

Show all ︎Show first 5

Misc. 5

  1. 高速電子顕微鏡法による原子ダイナミクスの直接観察 Peer-reviewed

    石川亮, 神保雄, 二塚俊洋, 川原一晃, 柴田直哉, 幾原雄一

    セラミックス　60　(5)　342-345　2025/05

  2. フッ化物電池用LaAl3負極の開発・微細構造解析 Peer-reviewed

    佐々野駿, 石川亮, 川原一晃, 柴田直哉, 幾原雄一

    セラミックス　59　(10)　698-701　2024/10

  3. チタン酸リチウムランタン単結晶による高リチウムイオン伝導の実証

    小林俊介, 横江大作, 桑原彰秀, 幾原雄一, 幾原雄一, 川原一晃, 藤原靖幸

    JFCC研究成果集　2023　2023

  4. リチウムイオン電池用正極膜内部の充放電による構造変化

    幾原裕美, 高翔, 高翔, FISHER Craig, 桑原彰秀, 森分博紀, 川原一晃, 石川亮, 幾原雄一, 幾原雄一

    JFCC研究成果集　2022　2022

  5. Structure Determination of Silicene on Ag(111) by Low-Energy Electron Diffraction

    Kazuaki Kawahara, Tetsuroh Shirasawa, Noriaki Takagi

    ISSP activity report 2013　42-43　2014/03

Presentations 55

  1. Br添加KSbF4のフッ化物イオン伝導

    川原一晃, 石川亮, 柴田直哉, 幾原雄一

    第66回電池討論会　2025/11/19

  2. 全三階変動正則化による超解像を用いた低解像度STEM像のノイズ除去

    川原一晃, 石川亮, 佐々野駿, 柴田直哉, 幾原雄一

    日本顕微鏡学会第81回学術講演会　2025/06/09

  3. Development of fluoride ion conductors based on LaF3

    Kazuaki Kawahara, Ryo Ishikawa, Shun Sasano, Naoya Shibata, Yuichi Ikuhara

    16th Pacific Rim Conference on Ceramic and Glass Technology including Glass & Optical Materials Division Meeting　2025/05/09

  4. Fluoride ion conductivity of bromine-doped KSbF4

    Kazuaki Kawahara, Ryo Ishikawa, Naoya Shibata, Yuichi Ikuhara

    2025/03/06

  5. Fluoride ion conductivity of halogen doped KSbF 4 (KSbF 3.9 X 0.1 : X=Cl, Br,

    Kazuaki Kawahara, Ryo Ishikawa, Naoya Shibata, Yuichi Ikuhara

    2024/11/22

  6. Fluoride ion conductivity of Rb-doped KSbF4

    Kazuaki Kawahara, Ryo Ishikawa, Naoya Shibata, Yuichi Ikuhara

    ECS PRiME 2024　2024/10/09

  7. Super-resolution of atomic-resolution STEM image by total third degree variation

    Kazuaki Kawahara, Ryo Ishikawa, Shun Sasano, Naoya Shibata, Yuichi Ikuhara

    2024/06/04

  8. Fluoride ion conductivity of halogen-doped KSbF4

    Kazuaki Kawahara, Ryo Ishikawa, Naoya Shibata, Yuichi Ikuhara

    2024/03/15

  9. Development of fluoride ion conductors based on LaF3

    Kazuaki Kawahara, Ryo Ishikawa, Shun Sasano, Naoya Shibata, Yuichi Ikuhara

    2023/11/29

  10. Atomic-resolution STEM image denoising by total variation regularization

    K. Kawahara, R. Ishikawa, S. Sasano, N. Shibata, Y. Ikuhara

    IMC20　2023/09/12

  11. Atomic-Resolution STEM Image Denoising by Total Variation Regularization

    K. Kawahara, R. Ishikawa, S. Sasano, N. Shibata, Y. Ikuhara

    IAMNano2023　2023/06/28

  12. 全三階変動を用いた原子分解能STEM像のノイズ除去

    川原一晃, 石川亮, 佐々野駿, 柴田直哉, 幾原雄一

    日本顕微鏡学会第79回学術講演会　2023/06/26

  13. LaF3を基にしたフッ化物イオン伝導体の開発

    川原一晃, 石川亮, 佐々野駿, 柴田直哉, 幾原雄一

    日本セラミックス協会2023年年会　2023/03

  14. Cs添加KSbF4のフッ化物イオン伝導

    川原一晃, 石川亮, 柴田直哉, 幾原雄一

    第63回電池討論会　2022/11

  15. Fluoride ion conductivity of Cs-doped KSbF4

    Kazuaki Kawahara, Ryo Ishikawa, Naoya Shibata, Yuichi Ikuhara

    23rd International Conference on Solid State Ionics　2022/07

  16. Total variation正則化を用いた原子分解能STEM像のノイズ除去

    川原一晃, 石川亮, 佐々野駿, 柴田直哉, 幾原雄一

    日本顕微鏡学会第78回学術講演会　2022/05

  17. Cs添加KSbF4(K1-xCsxSbF4)のフッ化物イオン伝導

    川原一晃, 石川亮, 柴田直哉, 幾原雄一

    日本セラミックス協会2022年年会　2022/03

  18. Rb添加KSbF4(K1-xRbxSbF4)のフッ化物イオン伝導

    川原一晃, 石川亮, 柴田直哉, 幾原雄一

    第62回電池討論会　2021/12

  19. Fluoride ion conductivity of potassium tetrafluoroantimonate

    Kazuaki Kawahara, Ryo Ishikawa, Kei Nakayama, Naoya Shibata, Yuichi Ikuhara

    The 14th Pacific Rim Conference of Ceramic Societies　2021/12

  20. Rb添加KSbF4のフッ化物イオン伝導

    川原一晃, 石川亮, 柴田直哉, 幾原雄一

    日本セラミックス協会 第34回秋季シンポジウム　2021/09

  21. KSbF4のフッ化物イオン伝導

    川原一晃, 石川亮, 仲山啓, 柴田直哉, 幾原雄一

    日本セラミックス協会2021年会　2021/03

  22. フルオロアンチモン酸カリウム(KSbxF1+3x)のフッ化物イオン伝導

    川原一晃, 石川亮, 仲山啓, 柴田直哉, 幾原雄一

    第61回電池討論会　2020/11

  23. 界面接合の実験と数理 Invited

    川原一晃, 井上和俊, 斎藤光浩, 荒船竜一, 林俊良, 高木紀明, 川合眞紀, 幾原雄一

    IMI workshop II: 材料科学における幾何と代数I　2020/09

  24. フルオロアンチモン(III)酸カリウムのフッ化物イオン伝導

    川原一晃, 石川亮, 柴田直哉, 幾原雄一

    日本セラミックス協会2020年会　2020/03

  25. Atomic structure and Li-ion conductivity of (La,Li)NbO3 electrolyte

    Kazuaki Kawahara, Ryo Ishikawa, Kei Nakayama, Takuma Higashi, Yumi Ikuhara, Teiichi Kimura, Naoya Shibata, Yuichi Ikuhara

    The 13th Pacific Rim Conference of Ceramic Societies　2019/10

  26. 情報理論を用いた画像解析

    川原一晃

    第19回結晶界面工学研究会　2019/09

  27. Li-ion conductivity of lithium lanthanum niobate polycrystals

    Kazuaki Kawahara, Ryo Ishikawa, Kei Nakayama, Takuma Higashi, Yumi Ikuhara, Teiichi Kimura, Naoya Shibata, Yuichi Ikuhara

    22nd International Conference on Solid State Ionics　2019/06

  28. (La,Li)NbO3固体電解質のイオン伝導と局所構造

    川原一晃, 石川亮, 仲山啓, 東拓磨, 木村禎一, 幾原裕美, 柴田直哉, 幾原雄一

    第59回電池討論会　2018/11

  29. 格子整合と数論

    川原一晃

    第18回結晶界面工学研究会　2018/09

  30. (Li,La)NbO3多結晶体の局所構造とイオン伝導

    川原一晃, 石川亮, 仲山啓, 東拓磨, 木村禎一, 幾原裕美, 柴田直哉, 幾原雄一

    日本セラミックス協会 第31回秋季シンポジウム　2018/09

  31. Ionic conductivity of lithium lanthanum niobate polycrystals: Electrochemical impedance spectroscopy analysis

    Kazuaki Kawahara, Takuma Higashi, Kei Nakayama, Ryo Ishikawa, Teiichi Kimura, Yumi Ikuhara, Naoya Shibata, Yuichi Ikuhara

    International meeting on lithium batteries 2018　2018/06

  32. 低速電子回折を用いたWTe2表面の構造解析 Invited

    川原一晃, Zeyuan Ni, 荒船竜一, 白澤徹郎, 林俊良, 南谷英美, 渡邉聡, 川合眞紀, 高木紀明

    日本表面科学会北海道東北関東支部合同セミナー　2017/11

  33. Application of Markov chain Monte Carlp method to curve fitting

    川原一晃

    第17回結晶界面工学研究会　2017/09

  34. 二テルル化タングステン表面の構造解析

    川原一晃, 荒船竜一, 白澤徹郎, 林俊良, Zeyuan Ni, 南谷英美, 渡邉聡, 川合眞紀, 高木紀明

    第36回表面科学学術講演会　2016/12

  35. Structure determination of multilayer silicene on Ag(111) by dynamical low- energy electron diffraction and scanning tunneling microscopy

    川原一晃, 白澤徹郎, 林俊良, 長尾遼, 荒船竜一, 高橋敏男, 川合眞紀, 高木紀明

    第7回真空・表面若手研究会　2016/12

  36. Structure Determination of Tungsten Telluride Surface

    川原一晃, 荒船竜一, 白澤徹郎, 林俊良, Zeyuan Ni, 南谷英美, 渡邉聡, 川合眞紀, 高木紀明

    表面界面スペクトロスコピー2016　2016/11

  37. 代数的整数論を応用した2次元格子整合理論

    川原一晃, 荒船竜一, 川合眞紀, 高木紀明

    日本物理学会2016年秋季大会　2016/09

  38. Ag(111)単結晶上に作製した多層シリセンの構造

    川原一晃, 白澤徹郎, 林俊良, 長尾遼, 塚原規志, 高橋敏男, 荒船竜一, 川合眞紀, 高木紀明

    日本物理学会2016年年次大会　2016/03

  39. Structure of silicene grown on Ag(111)

    Kazuaki Kawahara

    8th HOPE MEETING with Nobel Laureates　2016/03

  40. Ag(111)上に成長させた多層シリセンの構造

    川原一晃, 白澤徹郎, 林俊良, 荒船竜一, 長尾遼, 塚原規志, 高橋敏男, 川合眞紀, 高木紀明

    第35回表面科学学術講演会　2015/12

  41. 代数的整数論に基づいた2次元格子整合理論

    川原一晃, 荒船竜一, 川合眞紀, 高木紀明

    第6回真空・表面科学若手研究会　2015/12

  42. Ag(111)上に作製した多層シリセンの構造

    川原一晃, 白澤徹郎, 林俊良, 長尾遼, 塚原規志, 高橋敏男, 荒船竜一, 川合眞紀, 高木紀明

    表面界面スペクトロスコピー2015　2015/11

  43. Application of algebraic number theory to 2-dimensional lattice matching

    Kazuaki Kawahara, Ryuichi Arafune, Maki Kawai, Noriaki Takagi

    10th International Symposium on Atomic Level Characterizations for New Materials and Devices ’15　2015/10

  44. Ag(111)上シリセンの成長様式

    川原一晃, 望月出海, 白澤徹郎, 林俊良, 長尾遼, 荒船竜一, 川上直也, 和田健, 塚原規志, 高橋敏男, 兵頭俊夫, 川合眞紀, 高木紀明

    日本物理学会2015年秋季大会　2015/09

  45. Ag(111)上に成長させたシリセンの構造

    川原一晃, 荒船竜一, 林俊良, 白澤徹郎, 塚原規志, 高橋敏男, 川合眞紀, 高木紀明

    表面界面スペクトロスコピー2014　2014/12

  46. Determination of Silicene on Ag(111) by Low-Energy Electron Diffraction

    Kazuaki Kawahara, Tetsuroh Shirasawa, Ryuichi Arafune, Chung-Liang Lin, Toshio Takahashi, Maki Kawai, Noriaki Takagi

    The 7th International Symposium on Surface Science　2014/11

  47. 2次元格子整合の数学的考察

    川原一晃, 荒船竜一, 川合眞紀, 高木紀明

    日本物理学会2014年秋季大会　2014/09

  48. Structure determination of silicene on Ag(111) by low-energy electron diffraction

    Kazuaki Kawahara, Tetsuroh Shirasawa, Ryuichi Arafune, Chung-Liang Lin, Toshio Takahashi, Maki Kawai, Noriaki Takagi

    11th International Conference on the Structure of Surfaces　2014/07

  49. Structure Determination of Silicene on Ag(111) by Low Energy Electron Diffraction

    Kazuaki Kawahara, Tetsuroh Shirasawa, Ryuichi Arafune, Chung-Liang Lin, Toshio Takahashi, Maki Kawai, Noriaki Takagi

    Symposium on Surface and Nano Science 2014　2014/01

  50. 低速電子回折を用いたAg(111)上シリセンの構造解析

    川原一晃, 白澤徹郎, 荒船竜一, 林俊良, 高橋敏男, 川合眞紀, 高木紀明

    表面界面スペクトロスコピー2013　2013/12

  51. Structure Determination of Silicene on Ag(111) by Dynamical Low Energy Electron Diffraction

    Kazuaki Kawahara, Tetsuroh Shirasawa, Ryuichi Arafune, Chung-Liang Lin, Toshio Takahashi, Maki Kawai, Noriaki Takagi

    12th International Conference on Atomically Controlled Surfaces, Interfaces and Nanostructures　2013/11

  52. LEEDによるAg(111)上シリセンの構造解析

    川原一晃, 白澤徹郎, 荒船竜一, 林俊良, 高橋敏男, 川合眞紀, 高木紀明

    日本物理学会2013年秋季大会　2013/09

  53. Ag(111)基板上に作製したシリセン多層膜の構造

    川原一晃, 林俊良, 荒船竜一, 中村耕太郎, 長尾遼, 塚原規志, 高木紀明, 川合眞紀

    日本物理学会2013年年次大会　2013/03

  54. Ag(111)基板上に作製したシリセンの構造

    川原一晃, 林俊良, 荒船竜一, 塚原規志, 高木紀明, 川合眞紀

    日本物理学会2012年秋季大会　2012/09

  55. Structure property of silicene on Ag(111)

    Kazuaki Kawahara, Chung-Liang Lin, Ryuichi Arafune, Noriyuki Tsukahara, Noriaki Takagi, Maki Kawai

    14th International Conferenece on Vibrations At Surfaces　2012/09

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Industrial Property Rights 4

  1. プログラム、画像修復装置及び画像修復方法

    岡田真人, 片上舜, 久住太一, 柴田直哉, 石川亮, 川原一晃

    Property Type: Patent

  2. フッ化物イオン電池用負極活物質

    幾原雄一, 石川亮, 川原一晃, 佐々野駿

    Property Type: Patent

  3. Fluoride ion conductor and its manufacturing method

    Property Type: Patent

  4. フッ化物イオン電池用の正極活物質、フッ化物イオン電池、及びそれらの製造方法

    石川亮, 幾原雄一, 川原一晃, 佐々野駿

    Property Type: Patent

Research Projects 6

  1. High spatiotemporal-resolution STEM imaging for materials interface

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Research (Pioneering)

    Institution: The University of Tokyo

    2025/06 - 2028/03

  2. Development of super large-angle illumination STEM imaging

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (A)

    Institution: The University of Tokyo

    2024/04 - 2027/03

  3. Development of high-capacity cathode materials for fluoride ion batteries using double salts

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Early-Career Scientists

    Institution: The University of Tokyo

    2024/04 - 2027/03

  4. 粒界数理学の構築に基づく機能材料創出

    井上 和俊, 馮 斌, 川原 一晃

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業

    Category: 基盤研究(B)

    Institution: 東北大学

    2021/04 - 2025/03

    More details Close

    材料中には無数の格子欠陥が存在し、特に界面の原子構造は機能特性に多大な影響を及ぼすことが知られている。特に粒界は格子整合理論である対応格子理論によって大まかな分類がなされ、同一結晶同士の整合指標はΣ値として広く用いられてきた。しかしながら、異なる結晶同士の整合については整合指標が存在しない。本研究では、異種界面および非整合界面の格子定数を適切に近似することにより、対応格子理論の一般化を試みた。特に、同一結晶同士の整合の場合はΣ値に帰着するような格子整合指標を定義し、種々の格子の組み合わせに対して、整合する場合の相対回転角と対応する整合指標を系統的に求めた。可能な格子の組み合わせをマッピングすることにより、任意の格子定数比の異種界面・非整合界面に対して系統的に整合・非整合を議論することが出来るようになり、効率的なモデリングと材料探索、材料設計指針の立案に貢献できると期待される。 また、上記格子整合理論に基づき、複数の非整合界面について適切なモデリングと構造最適化、および電子状態解析を行った。格子定数の組み合わせによっては周期性に応じて複数のモデルを構築することは可能であり、実材料を再現するには超長周期のモデルが必要な場合がある。しかしながら、短周期構造であれ長周期構造であれ、酸化物の界面では電気特性に関しては顕著な違いが生じないことが示唆された。この知見は計算コストの削減に有用であると考えられる。次年度に、対応するモデル試料を作成し、走査透過型電子顕微鏡観察を併用して結果を総括する。

  5. Creation of new high-performance fluoride ion conductors using double salts

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Early-Career Scientists

    Category: Grant-in-Aid for Early-Career Scientists

    Institution: The University of Tokyo

    2021/04/01 - 2024/03/31

  6. １４族元素からなる２次元ハニカムシートの物性開拓

    川原 一晃

    Offer Organization: 日本学術振興会

    System: 科学研究費助成事業 特別研究員奨励費

    Category: 特別研究員奨励費

    Institution: 東京大学

    2015/04/24 - 2017/03/31

    More details Close

    申請者の研究テーマは新奇ディラック電子系の探索と物性評価を行い、新しい機能性材料としての可能性を探ることである。今年度は以下の2つの項目について研究を行った。 (1)新奇二次元ハニカムシートの創成 グラフェンなどの14族元素からなる二次元ハニカム物質はディラック電子系である。申請者は新奇ハニカム物質創成を目指して、二硫化モリブデン上に様々な条件でスズ、鉛を蒸着した。電子回折像を観察することで二次元シートが成長するか否かを調査した。スズを蒸着したときは、蒸着条件に関わらず二次元シートは成長しなかった一方、基板を100-200℃に保って鉛を蒸着した後では1x1の回折パターンが観測された。これは鉛の二次元シートの合成に成功した可能性を示唆する結果である。しかし現状その構造は不明であり、今後構造解析を行う。 (2)テルル化タングステン表面の構造解析 金属カルコゲン層状物質であるテルル化タングステン(WTe2)は、3次元的なディラック電子系(ワイル半金属)の候補として注目されている。ワイル半金属表面には、トポロジカルに保護されたフェルミ弧表面状態が存在すると言われており、角度分解光電子分光などの表面敏感な実験手法により電子状態の研究が行われている。電子状態に関する知見は蓄積されている一方、WTe2の表面構造とバルクの層状構造とを比較した例はない。本研究ではWTe2表面構造を低速電子回折によって決定し、第一原理計算による最適構造と比較した。最表面のTe原子がバルクと比べて表面垂直方向に変位するなどの表面緩和があること、その緩和は第一原理計算でも再現されることがわかった[APEX 10, 045702 (2017).]。本成果はWTe2の表面構造を初めて実験的に詳細に決定した結果である。表面構造の詳細な決定は、WTe2の電子物性のさらなる理解につながる成果である。

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Teaching Experience 1

  1. Student Experient　The University of Tokyo

Academic Activities 1

  1. 第6回 真空・表面科学若手研究会

    2015/12/04 - 2015/12/04

    Activity type: Academic society, research group, etc.