このエントリーをはてなブックマークに追加
ID 30706
本文ファイル
著者
Tanaka, Tomoo
Mano, Satomi
NDC
物理学
抄録(英)
We report structural, transport, and thermal properties of type-I clathrate K8Ga8Sn38 single crystals grown by the self-flux method. Single-crystal x-ray diffraction analysis confirmed that the guest K+ ion locates on the center in the tetrakaidecahedron composed of Ga and Sn atoms. The thermopower is largely negative,-200μ V/K at room temperature, irrespective of the flux used during growth Ga or Sn . The thermal conductivity κ(T) exhibits a large peak at 14 K. These observations in K8Ga8Sn38 are ontrasting with the splitting of the guest site and the glasslike behavior in κ(T) reported for type-I Ba8Ga16Sn30 although the free space for the guest is almost the same in both compounds. The electrostatic potential for the tetrakaidecahedron was calculated using the occupation probabilities of Ga ions in the three sites on the cage. It is found that the off-centered state is stabilized for the Ba2+ ions in Ba8Ga16Sn30 by the partial occupation of Ga anion in the 16i site while the on-center state for K8Ga8Sn38 is stabilized by the strongly preferred occupation of Ga anions in the 6c site. We conclude that the charge distribution on the cage is crucial for the splitting of the guest site into off-center positions in the tetrakaidecahedron of the type-I clathrate.
掲載誌名
Physical Review B
81巻
16号
開始ページ
165110-1
終了ページ
165110-6
出版年月日
2010
出版者
The American Physical Society
ISSN
1098-0121
NCID
出版者DOI
言語
英語
NII資源タイプ
学術雑誌論文
広大資料タイプ
学術雑誌論文
DCMIタイプ
text
フォーマット
application/pdf
著者版フラグ
publisher
権利情報
Copyright (c) 2010 The American Physical Society
関連情報URL
部局名
先端物質科学研究科