Synthesis and crystal chemical characterization of the pyrochlore type MgZrSi₂O₇

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• 作者：Junshan Xu^a ; ^b ; ^{xjsn@mail.ustc.edu.cn"" rel=""nofollow} ; Eiji Ito^b ; Daisuke Yamazaki^b ; Xinzhuan Guo^b ; Xiaoping Wu^a
• 关键词：Chemical synthesis ; Crystal structure ; Powder diffraction ; Rietveld analysis
• 刊名：Materials Chemistry and Physics
• 出版年：2011
• 出版时间：15 August 2011
• 年：2011
• 卷：128
• 期：3
• 页码：410-412
• 全文大小：300 K

文摘

The pyrochlore type of MgZrSi₂O₇ was synthesized at 25 GPa and 1500 °C using a Kawai-type, multi-anvil apparatus. Powder X-ray diffraction and Rietveld analysis revealed that the phase assumed the pyrochlore structure (space group , cubic) with the lattice parameter a = 9.2883(1) Å and the structural parameter x = 0.4295(4). Chemical analysis by the electron probe microanalysis (EPMA) confirmed the stoichiometry of MgZrSi₂O₇. It was demonstrated that the eight-fold coordinated 16c site is randomly occupied by both Mg²⁺ and Zr⁴⁺ ions in a 1:1 ratio. The high ionic radius ratio R_A/R_B (where A and B denote Mg + Zr and Si, respectively) of 2.22 necessitates a relatively high pressure to stabilize the pyrochlore structure.