Structural properties and thermodynamic stability of Ba-doped silicon type-I clathrates synthesized under high pressure

Physical Review B - Condensed Matter and Materials Physics 64 巻 4 号 045206- 頁 2001-07-15 発行
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タイトル ( eng )
Structural properties and thermodynamic stability of Ba-doped silicon type-I clathrates synthesized under high pressure
作成者
Kitano Akiko
Moriguchi Koji
Yoneyama Mitsuharu
Munetoh Shinji
Shintani Akira
Nishibori Eiji
Takata Masaki
Sakata Makoto
収録物名
Physical Review B - Condensed Matter and Materials Physics
64
4
開始ページ 045206
抄録
We present a joint experimental and theoretical study of the stability and structural properties of Ba-doped silicon type-I clathrates Ba8Si46 synthesized under high pressures. The thermodynamic stability of Ba8Si46 under high pressure has been discussed from the total energy calculations of some barium silicides within the local density approximation (LDA). We have theoretically found that pressure favors the formation of the clathrate phase as experimentally observed. We have also performed a synchrotron x-ray-diffraction experiment of Ba8Si46 prepared under high pressures. Some of the missing endohedral Ba elements in the small cage of Si(20) have been observed by x-ray crystallography, while big cages of Si(24) are found to be completely occupied by Ba elements. The stabilization energies of Ba atoms in the endohedral sites estimated within the present LDA calculation suggest that this is presumably attributed to the energetical site preference of Ba atoms between d(6) and a(2) sites. In addition, the isothermal parameter of Ba in the big cage of Si(24) has been found to be larger than that in the small Si(20) unit, which is consistent with some theoretical predictions in earlier works.
NDC分類
物理学 [ 420 ]
言語
英語
資源タイプ 学術雑誌論文
出版者
American Physical Society
発行日 2001-07-15
権利情報
Copyright (c) 2001 American Physical Society
出版タイプ Version of Record(出版社版。早期公開を含む)
アクセス権 オープンアクセス
収録物識別子
[NCID] AA11187113
[ISSN] 1098-0121
[DOI] 10.1103/PhysRevB.64.045206
[DOI] http://dx.doi.org/10.1103/PhysRevB.64.045206