Postperovskite Phase Transition of ZnGeO3: Comparative Crystal Chemistry of Postperovskite Phase Transition from Germanate Perovskites

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• 作者：Hitoshi Yusa ; Taku Tsuchiya ; Masaki Akaogi ; Hiroshi Kojitani ; Daisuke Yamazaki ; Naohisa Hirao ; Yasuo Ohishi ; Takumi Kikegawa
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：November 3, 2014
• 年：2014
• 卷：53
• 期：21
• 页码：11732-11739
• 全文大小：515K
• ISSN：1520-510X

文摘

The postperovskite phase of ZnGeO₃ was confirmed by laser heating experiments of the perovskite phase under 110鈥?30 GPa at high temperature. Ab initio calculations indicated that the phase transition occurs at 133 GPa at 0 K. This postperovskite transition pressure is significantly higher than those reported for other germanates, such as MnGeO₃ and MgGeO₃. The comparative crystal chemistry of the perovskite-to-postperovskite transition suggests that a relatively elongated b-axis in the low-pressure range resulted in the delay in the transition to the postperovskite phase. Similar to most GdFeO₃-type perovskites that transform to the CaIrO₃-type postperovskite phase, ZnGeO₃ perovskite eventually transformed to the CaIrO₃-type postperovskite phase at a critical rotational angle of the GeO₆ octahedron. The formation of the postperovskite structure at a very low critical rotational angle for MnGeO₃ suggests that relatively large divalent cations likely break down the corner-sharing GeO₆ frameworks without a large rotation of GeO₆ to form the postperovskite phase.