Local crystal structure and phase stability of rare earth-metal borides with boron dimensional network structure

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K05643
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 36010:Inorganic compounds and inorganic materials chemistry-related
• Research Institution: Kyushu University (2020-2021); Tohoku University (2019)
• Principal Investigator: Yubuta Kunio 九州大学, 工学研究院, 学術研究員 (00302208)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 結晶構造解析 / 相安定性 / 局所構造 / 単結晶育成 / 電子回折トモグラフィー / 4D-STEM 観察

Outline of Final Research Achievements

Various structural modulations appearing in rare earth-metal (mainly transition metal)-borides with boron dimensional network structures, which are strongly correlated with characteristic properties of interest to many researchers, are revealed. In particular, the local crystal structure provides important insights into the phase stability of rare earth-metal-borides with a characteristic boron dimensionality network structure.
Atomic resolution STEM observations led to 'atomic displacement analysis', providing insight into 'fluctuations of atomic arrangement' in borides. By combination with atomic-resolution elemental mapping using spectroscopy, the investigation of non-stoichiometry at the atomic arrangement level was advanced. Electron diffraction tomography has also revealed structural features of diffuse scattering.

Free Research Field

無機構造化学

Academic Significance and Societal Importance of the Research Achievements

ホウ素次元性ネットワーク構造をもつ希土類－金属－ホウ化物における構造ブロック・インテグレーションでは，複数の構造ブロックを組み合わせて新しい結晶構造を作り上げる．それぞれの構造ブロック固有（intra-）の特徴に加えて数種類の構造ブロック間（inter-）の相関にも秩序が見いだされ，新たな構造次元性を伴う相乗効果が生まれる．このような観点から，従来の材料開発のベースとなっている3次元結晶構造という基本概念に，構造ブロック・インテグレーションが与える余剰な構造次元性を与えることで，ホウ化物材料のもつ特性（磁性材料，熱電変換材料，触媒材料など）を新たなステージに引き上げることが可能になる．