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Kyutacarは九州工業大学で生産された研究成果を オープンアクセスで提供する機関リポジトリシステムです。 Kyutacar is open-access repository of research by members of the Kyushu Institute of Technology.
Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan
Graduate School of Engineering, Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu 804-8550, Japan
抄録
Nd2Fe14B is a high-density Fe cluster containing 56 Fe atoms in one unit cell. We investigated the crystallographic structure of an isotropic Nd2Fe14B magnet comprising nanocrystals of a size of ~30 nm at pressures up to 2 GPa. The results of X-ray diffraction measurements using Rietveld refinement revealed the displacements of each Fe atomic site in the Fe cluster, Nd, and B atomic sites. The lattice constants, a and c, of tetragonal symmetry decreased proportionally with external pressure, whereas the shrinkage ratio for both a and c changed at approximately 0.5 GPa. However, each atomic position exhibited non-monotonic pressure dependence. The trend of displacement of atomic positions changed at a characteristic pressure of 0.4 ± 0.1 GPa. When exceeded, most atoms shifted to the direction opposite their displacement at lower pressures. Thus, they exhibited restoration tendencies toward the positions at ambient pressure. The bond angles and bond lengths among Nd, Fe, and B atoms also exhibited characteristic pressure dependences. As pressure increased, the basal triangle of the trigonal prism in the Fe cluster layers distorted up to ~0.5 GPa, whereas the strain of the trigonal prism gradually reduced just above 0.5 GPa. The atomic position of the heaviest Nd atoms was a key structural parameter to characterize the change.
雑誌名
Journal of Magnetism and Magnetic Materials
巻
498
ページ
166163-1 - 166163-9
発行年
2019-11-21
出版者
Elsevier
ISSN
0304-8853
DOI
https://doi.org/10.1016/j.jmmm.2019.166163
権利
Copyright (c) 2019 Elsevier B.V. All rights reserved.
日本十進分類法
459
その他のタイトル
Crystal structure of high–density Fe56 cluster Nd2Fe14B under high pressure
Crystal structure of high-density Fe56 cluster Nd2Fe14B under high pressure
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