Tetragonal structure of CaSiO3 perovskite above 20 GPa
Tetragonal structure of CaSiO3 perovskite above 20 GPa
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DOI：
10.1029/2002gl016148
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发表时间：
2002-12
影响因子：
5.2
通讯作者：
S. Shim;R. Jeanloz;T. Duffy
中科院分区：
文献类型：
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作者：
S. Shim;R. Jeanloz;T. Duffy
在20-46 GPa下对在激光加热金刚石单元中合成的CaSiO 3钙钛矿（Ca-pv）进行高分辨率同步加速器X射线衍射测量。加热后，我们观察到立方200和211衍射线的峰分裂，这归因于Ca-pv的四重畸变。当K 0 T '= 4时，四方相的体积模量为255 ± 5 GPa。观测到的分裂线的强度和d间距表明c轴比a轴短（c/a = 0.993 − 0.996）。这与SiO 6八面体围绕a轴的旋转或SiO 6八面体畸变（沿c轴的Si-O键沿着比a轴短）相容，只要观察到的相具有四面体晶胞。Ca-pv中的这些结构扭曲会影响其物理性质和大阳离子的容量。
High‐resolution synchrotron X‐ray diffraction measurements were performed at 20–46 GPa on CaSiO3 perovskite (Ca‐pv) synthesized in a laser heated diamond cell. After heating, we observed peak splittings for the cubic 200 and 211 diffraction lines, attributable to a tetragonal distortion of Ca‐pv. The bulk modulus of the tetragonal phase is 255 ± 5 GPa for K0T′ = 4. The observed intensities and d‐spacings of the split lines indicate that the c‐axis is shorter than the a‐axes (c/a = 0.993 − 0.996). This is compatible with either SiO6 octahedron rotation around the a‐axes or SiO6 octahedron distortion (shorter Si‐O bonds along the c‐axis than the a‐axes), provided that the observed phase has a tetragonal unit cell. These structural distortions in Ca‐pv can affect its physical properties and capacity for large cations.