Stability and equation of state of MgGeO3 post-perovskite phase
Stability and equation of state of MgGeO3 post-perovskite phase
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DOI：
10.2138/am.2005.1702
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发表时间：
2005-01-01
影响因子：
3.1
通讯作者：
Sata, N
中科院分区：
文献类型：
--
作者：
Hirose, K;Kawamura, K;Sata, N
采用同步辐射X射线衍射技术研究了MgGeO 3钙钛矿在高温高压下的相变。结果表明，在1800 K时，当压力大于63 GPa时，样品转变为CaIrO 3型后钙钛矿相。在过渡压力下，密度增加了1.5%。这些观测结果证实了MgGeO 3是MgSiO（3）的低压类似物，最近在125 GPa和2500 K以上发现了MgSiO（3）的类似相变。在300 K时从79 GPa减压到6 GPa的MgGeO 3后钙钛矿相的晶胞参数表明，b轴比a轴和c轴显著更可压缩，这可能是由于GeO 6-八面体片沿沿着B堆叠结构。体积模量测定为K-0 192（+/-5）GPa，体积模量的固定压力导数K-1为4。
A phase transition of MgGeO3 perovskite was examined at high-pressure and -temperature using synchrotron X-ray diffraction measurements. The results demonstrate that it transforms to a CaIrO3-type post-perovskite phase above 63 GPa at 1800 K. The density increase is 1.5% at the transition pressure. These observations confirm that MgGeO3 is a low-pressure analogue toMgSiO(3), for which a similar phase transition was recently found above 125 GPa and 2500 K. The unit-cell parameters of MgGeO3 post-perovskite phase obtained at 300 K during decompression from 79 to 6 GPa show that the b-axis is significantly more compressible than are the a- and c-axes, which could be due to the GeO6-octahedral sheet stacking structure along b. The bulk modulus was determined to be K-0 192(+/-5) GPa with a fixed pressure derivative of the bulk modulus, K-1, of 4.