Crystal structure of SrGeO3 in the high-pressure perovskite-type phase

Acta Crystallographica Section E: Crystallographic Communications

Keiko Fujiwara¹  Akihiko Nakatsuka¹  Akira Yoshiasa²  Osamu Ohtaka³  Hiroshi Arima⁴ 

[1] Graduate School of Science and Engineering, Yamaguchi University, Ube 755-8611, Japan;Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan;Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan;Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan;

关键词: crystal structure;    strontium germanate;    perovskite;    high-pressure phase;   

DOI  :  10.1107/S2056989015007264

来源: DOAJ

【 摘 要 】

Single crystals of the SrGeO3 (strontium germanium trioxide) high-pressure phase have been synthesized successfully at 6 GPa and 1223 K. The compound crystallizes with the ideal cubic perovskite-type structure (space group Pm-3m), which consists of a network of corner-linked regular GeO6 octahedra (point-group symmetry m-3m), with the larger Sr atoms located at the centers of cavities in the form of SrO12 cuboctahedra (point-group symmetry m-3m) in the network. The degrees of covalencies included in the Sr—O and the Ge—O bonds calculated from bond valences are 20.4 and 48.9%, respectively. Thus, the Ge—O bond of the GeO6 octahedron in the SrGeO3 perovskite has a strong covalency, comparable to those of the Si—O bonds of the SiO4 tetrahedra in silicates with about 50% covalency. The thermal vibrations of the O atoms in the title compound are remarkably suppressed in the directions of the Ge—O bonds. This anisotropy ranks among the largest observed in stoichiometric cubic perovskites.

【 授权许可】

Unknown