Synthesis and crystal chemical characterization of the pyrochlore type MgZrSi2O7
Synthesis and crystal chemical characterization of the pyrochlore type MgZrSi2O7
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DOI：
10.1016/j.matchemphys.2011.03.017
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发表时间：
2011-08
影响因子：
4.6
通讯作者：
Junshan Xu;E. Ito;D. Yamazaki;Xinzhuan Guo;Xiaoping Wu
中科院分区：
文献类型：
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作者：
Junshan Xu;E. Ito;D. Yamazaki;Xinzhuan Guo;Xiaoping Wu
利用Kawai型多顶锤装置，在25 Gpa、1500℃的条件下合成了烧绿石型的镁锆硅氧化物。粉末X射线衍射和Rietveld分析表明，该相呈烧绿石结构(空间群Fd3‘m，立方)，晶胞参数a=9.2883(1)ä，结构参数x=0.4295(4)。电子探针化学分析(EPMA)证实了该化合物的化学计量比。结果表明，镁离子和锆离子以1：1的比例随机占据了8配位的16c位。较高的离子半径比RA/RB(其中A和B分别表示Mg+Zr和Si)为2.22，需要相对较高的压力来稳定烧绿石结构。
The pyrochlore type of MgZrSi 2 O 7 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 F d 3¯ m, 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 MgZrSi 2 O 7. It was demonstrated that the eight-fold coordinated 16c site is randomly occupied by both Mg 2+ and Zr 4+ 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.