Creation of a New Family of Oxide Ion Conductors and Elucidation of the Conduction Mechanism

• Project/Area Number: 19K23647
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0502:Inorganic/coordination chemistry, analytical chemistry, inorganic materials chemistry, energy-related chemistry, and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Murakami Taito 東京工業大学, 理学院, 特任助教 (60846509)
• Project Period (FY): 2019-08-30 – 2021-03-31
• Project Status: Completed (Fiscal Year 2020)
• Budget Amount: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000); Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
• Keywords: 酸化物 / 酸化物イオン伝導体 / プロトン伝導体 / 結晶構造 / 中性子回折測定 / 六方ペロブスカイト関連構造 / 構造解析 / 結合原子価法 / イオン伝導体

Outline of Research at the Start

酸化物イオン伝導体の研究は数多いが、研究対象は特定の結晶構造に限られていた。本課題では、六方ペロブスカイト関連酸化物の酸化物イオン伝導体を探索し、① 高い伝導度を持つ新材料を発見し、② 中性子・放射光X線回折と最大エントロピー法を駆使して高伝導度の起源を明らかにする。対象となる候補物質は数百種類にのぼるが、理論的手法を駆使して候補物質を効率的に選定・発見を目指す。

Outline of Final Research Achievements

We found that the composition of the hexagonal perovskite-related oxide Ba7Nb4MoO20 with excess oxygen shows high oxide ion conductivity at medium and low temperatures. Furthermore, the structural analysis to the neutron diffraction data shows that the oxide ions diffuse around Ba in a two-dimensional manner. We also found that the hexagonal perovskite-related oxide Ba5Er2Al2ZrO13 shows high proton conductivity at medium and low temperatures without chemical substitution, which is attributed to the oxygen-deficient layer. These results were published in the American chemical journal J. Am. Chem. Soc. and a patent is pending.

Academic Significance and Societal Importance of the Research Achievements

酸化物イオン伝導体・プロトン伝導体の研究はともに特定の結晶構造に属する物質の研究が大多数であり、本研究で新しいイオン伝導体ファミリーとして六方ペロブスカイト関連酸化物を発見して論文と特許にまとめたことは学術的および社会的に意義深い．特に、本研究で発見した六方ペロブスカイト関連プロトン伝導体は、結晶構造中に元々存在する酸素欠損層を生かして化学置換なしで高い伝導度を示すという画期的なものであり、エネルギー問題と環境問題を解決する一助になると期待される．

Research Products

• [Int'l Joint Research] ANSTO(オーストリア)
• [Journal Article] Single-crystal growth, structure and luminescence properties of Cs2HfCl3Br3 (2020)
  • Author(s): S. Kodama, S. Kurosawa, K. Fujii, T. Murakami, M. Yashima, J. Pejchal, R. Kral, M. Nikl, A. Yamaji, M. Yoshino, S. Toyoda, H. Sato, Y. Ohashi, K. Kamada, Y. Yokota, A. Yoshikawa
  • Journal Title: Optical Materials Volume: 106 Pages: 109942-109942
  • DOI: 10.1016/j.optmat.2020.109942
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] High proton conductivity in Ba5Er2Al2ZrO13, a hexagonal perovskite-related oxide with intrinsically oxygen-deficient layers. (2020)
  • Author(s): Murakami, T., Hester, J. R., & Yashima, M.
  • Journal Title: Journal of the American Chemical Society Volume: 142 Pages: 11653-11657
  • DOI: 10.1021/jacs.0c02403
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Synthesis and Photoluminescence Properties of Rare-Earth-Activated Sr3-xAxAlO4H (A = Ca, Ba; x = 0, 1): New Members of Aluminate Oxyhydrides (2020)
  • Author(s): Tong Wu, Kotaro Fujii, Taito Murakami, Masatomo Yashima, Satoru Matsuishi
  • Journal Title: Inorganic Chemistry Volume: 59 Pages: 15384-15393
  • DOI: 10.1021/acs.inorgchem.0c02356
  • Peer Reviewed
• [Presentation] Ba2ScAlO5におけるプロトン伝導と伝導メカニズム (2021)
  • Author(s): 村上泰斗、八島 正知、Maxim Avdeev, James Haster
  • Organizer: 日本セラミックス協会2021年年会
• [Presentation] 新構造型プロトン伝導体Ba5Er2Al2ZrO13の発見 (2020)
  • Author(s): 村上泰斗、八島 正知、James Haster
  • Organizer: 日本セラミックス協会 2020年年会
• [Presentation] 本質的な酸素欠損層を持つ新型プロトン伝導体の発見 (2020)
  • Author(s): 村上泰斗、八島 正知、James Haster
  • Organizer: 日本セラミックス協会第33回秋季シンポジウム
  • Invited
• [Presentation] 機能性複合アニオン酸化物の構造と物性 (2020)
  • Author(s): 村上泰斗
  • Organizer: 新学術「複合アニオン」の第四回公開シンポジウム
  • Int'l Joint Research
• [Presentation] Relationship between the crystal structure and electrical properties of an oxide ion conductor with hexagonal perovskite-type structure (2019)
  • Author(s): Taito Murakami, Takafumi Tsujiguchi, Yuichi Sakuda, Yuta Yasui, Ping Miao, Masato Hagihara, Shuki Torii, Takashi Kamiyama, Kotaro Fujii, Masatomo Yashima
  • Organizer: The 13th Pacific Rim Conference of Ceramic Societies (PACRIM13)
• [Patent(Industrial Property Rights)] SOLID ELECTROLYTE, ELECTROLYTE LAYER AND BATTERY (2019)
  • Inventor(s): 八島正知、辻口峰史、藤井孝太郎、丹羽栄貴、作田祐一、村上泰斗、他
  • Industrial Property Rights Holder: 八島正知、辻口峰史、藤井孝太郎、丹羽栄貴、作田祐一、村上泰斗、他
  • Industrial Property Rights Type: 特許
  • Filing Date: 2019
  • Acquisition Date: 2020
  • Overseas