2019年11月
Pressure-Induced Collapse of the Guest Eu Off-Centering in Type-I Clathrate Eu8Ga16Ge30
Journal of the Physical Society of Japan
- 巻
- 88
- 号
- 11
- 開始ページ
- 114601
- 終了ページ
- 114601
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.7566/JPSJ.88.114601
- 出版者・発行元
- Physical Society of Japan
We have revealed the pressure-induced collapse of the guest Eu off-centering in type-I clathrate Eu8Ga16Ge30 by the measurements of extended X-ray absorption fine structure (EXAFS) at the Ge K-edge in a temperature range of 10-300 K. Our analysis of the EXAFS spectra at ambient pressure confirmed that the guest Eu is located in the off-centered positions Delta(offset) = 0.39(1) angstrom away from the center of the Ga/Ge tetradodecahedron cage (14-cage). However, with applying pressure to 13.1 GPa, Delta(offset) decreases to zero, and the atomic density of Eu is concentrated near the center of the 14-cage with a broad distribution. The present result demonstrates a close relationship between Delta(offset) and the size of the cage Delta(offset) decreases when the 14-cage shrinks by applying pressure. With further compression, we have observed a drastic change in the EXAFS spectra due to amorphization. In the amorphous phase, the first nearest neighbor Ge-Ga/Ge bond is longer than in the crystal phase, whereas the guest Eu atom is located randomly with respect to the Ge atoms.
- リンク情報
- ID情報
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- DOI : 10.7566/JPSJ.88.114601
- ISSN : 0031-9015
- eISSN : 1347-4073