Tokuda Makoto, Yoshiasa Akira, Mashimo Tsutomu, Iishi Kazuake, Nakatsuka Akihiko
Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555, Japan.
Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Ube 755-8611, Japan.
Acta Crystallogr C Struct Chem. 2018 Apr 1;74(Pt 4):460-464. doi: 10.1107/S2053229618003741. Epub 2018 Mar 14.
Single crystals of the vanadate garnet CaNaCdVO (dicalcium sodium dicadmium trivanadate) were synthesized using the floating-zone method and the crystal structure was investigated using single-crystal X-ray diffraction. We considered the effectiveness of substitution of the Y-site cation with reference to previous structural studies of vanadate garnets. The structures of vanadate garnets are subject to geometric constraints similar to those of silicate garnets. These constraints force the tetrahedral-dodecahedral shared edge length in vanadate garnets to become shorter than the unshared dodecahedral edge length, as in ugrandite (uvarovite, grossular and andradite) garnets. However, the vanadate garnet CaNaCdVO exhibits the normal structural feature, similar to pyralspite (pyrope, almandine and spessartine) garnets, namely that the dodecahedral-dodecahedral shared edge length is shorter than the unshared dodecahedral edge length. With increasing ionic radius of the Y-site cation, the atomic coordinates x, y and z of oxygen adopt values which satisfy Pauling's third rule.
采用浮区法合成了钒酸钆石榴石CaNaCdVO（二钙钠二镉三钒酸盐）单晶，并利用单晶X射线衍射对其晶体结构进行了研究。参照先前对钒酸钆石榴石的结构研究，我们考虑了Y位阳离子替代的有效性。钒酸钆石榴石的结构受到与硅酸盐石榴石类似的几何限制。这些限制使得钒酸钆石榴石中四面体 - 十二面体的共享边长比未共享的十二面体边长更短，就像钙铝榴石族（钙铬榴石、钙铝榴石和钙铁榴石）石榴石一样。然而，钒酸钆石榴石CaNaCdVO呈现出与铝榴石族（镁铝榴石、铁铝榴石和锰铝榴石）石榴石相似的正常结构特征，即十二面体 - 十二面体的共享边长比未共享的十二面体边长更短。随着Y位阳离子离子半径的增加，氧原子的坐标x、y和z采用满足鲍林第三规则的值。
