High-pressure behavior of MnGeO3 and CdGeO3 perovskites and the post-perovskite phase transition |
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| Authors: | Shigehiko Tateno Kei Hirose Nagayoshi Sata Yasuo Ohishi |
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| Institution: | (1) Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, 152-8551 Meguro, Tokyo, Japan;(2) Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan;(3) Japan Synchrotron Radiation Research Institute, Mikazuki-cho, Sayo-gun, Hyogo, Japan |
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| Abstract: | The stability and high-pressure behavior of perovskite structure in MnGeO3 and CdGeO3 were examined on the basis of in situ synchrotron X-ray diffraction measurements at high pressure and temperature in a laser-heated diamond-anvil cell. Results demonstrate that the structural distortion of orthorhombic MnGeO3 perovskite is enhanced with increasing pressure and it undergoes phase transition to a CaIrO3-type post-perovskite structure above 60 GPa at 1,800 K. A molar volume of the post-perovskite phase is smaller by 1.6% than that of perovskite at equivalent pressure. In contrast, the structure of CdGeO3 perovskite becomes less distorted from the ideal cubic perovskite structure with increasing pressure, and it is stable even at 110 GPa and 2,000 K. These results suggest that the phase transition to post-perovskite is induced by a large distortion of perovskite structure with increasing pressure. |
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| Keywords: | Post-perovskite Perovskite Phase transition High-pressure experiment Diamond-anvil cell |
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