Synthesis and crystallographic studies of garnet-type AgCa₂Mn₂V₃O₁₂ and NaPb₂Mn₂V₃O₁₂

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• 作者：Junji Awaka ; Norihito Kijima ; Junji Akimoto ; Shoichi Nagata
• 关键词：A. Inorganic compounds ; A. Oxides ; B. Chemical synthesis ; C. X-ray diffraction ; D. Crystal structure
• 刊名：Journal of Physics and Chemistry of Solids
• 出版年：2008
• 期刊代码：69_00223697
• 类别：ch
• 出版时间：July 2008
• 卷：69
• 期：7
• 页码：1740-1746
• 文件大小：418 K

摘要

High-purity powder specimens of AgCa₂Mn₂V₃O₁₂ and NaPb₂Mn₂V₃O₁₂ have been successfully synthesized by solid-state chemical reaction. The Rietveld refinements from X-ray powder diffraction data verified that these compounds have the garnet-type structure (space group , No. 230) with the lattice constant of a=12.596(2) Å for AgCa₂Mn₂V₃O₁₂ and a=12.876(2) Å for NaPb₂Mn₂V₃O₁₂. Calculation of the bond valence sum supported that Mn is divalent and V is pentavalent in these garnets. Estimation of the quadratic elongation and the bond angle variance showed that the distortions of the MnO₆ octahedra and the VO₄ tetrahedra are significantly suppressed. Our new results of AgCa₂Mn₂V₃O₁₂ and NaPb₂Mn₂V₃O₁₂ are compared to those of AgCa₂M₂V₃O₁₂ and NaPb₂M₂V₃O₁₂ (M=Mg, Co, Ni, Zn).