Silicate perovskite from phase transformations of pyrope‐garnet at high pressure and temperature
Silicate perovskite from phase transformations of pyrope‐garnet at high pressure and temperature
复制标题
DOI：
10.1029/gl001i006p00277
复制
发表时间：
1974-10
影响因子：
5.2
通讯作者：
Lin‐gun Liu
中科院分区：
文献类型：
--
作者：
Lin‐gun Liu
天然和合成镁铝榴石都在金刚石压砧机中被压缩到300千巴以上的压力，并通过连续YAG激光器加热到800°C以上的温度。X射线衍射结果表明，天然镁铝榴石经淬火和减压后转变为钙钛矿结构的单相，而合成镁铝榴石则转变为MgSiO 3（钙钛矿）和Al 2 O3（Al 2 O3）的混合物。天然镁铝榴石的正交钙钛矿晶格参数为ao = 4.816 ± 0.004 A，bo = 4.973 ± 0.004 A和co = 6.997 ± 0.006 A，Z = 4。MgSiO 3（钙钛矿）的正交晶胞尺寸为ao = 4.818 ± 0.005 A，bo = 4.869 ± 0.005 A，和co = 6.906 ± 0.007 A，Z=4。MgSiO 3钙钛矿的计算密度因此为4.12 g/cm³，或比等化学混合氧化物密度高3.7%。这些实验是硅酸盐石榴石中静态高压相变的第一个证明，也是钙钛矿结构中存在纯硅酸盐的第一个例子。
Both natural and synthetic pyrope have been compressed to pressures above 300 kbar in a diamond-anvil press and heated to temperatures above 800°C by a continuous YAG laser. After quenching and release of pressure, X-ray diffraction shows that the natural pyrope transforms to a single phase with perovskite-like structure whereas the synthetic pyrope disproportinates into a mixture of MgSiO3 (perovskite) plus Al2O3 (corundum). The orthorhombic perovskite lattice parameters for the natural pyrope are ao = 4.816 ± 0.004 A, bo = 4.973 ± 0.004 A, and co = 6.997 ± 0.006 A with Z = 4. The orthorhombic cell dimensions for MgSiO3 (perovskite) are ao = 4.818 ± 0.005 A, bo = 4.869 ± 0.005 A, and co = 6.906 ± 0.007 A with Z=4. The calculated density of MgSiO3 perovskite is thus 4.12 g/cm³, or 3.7% denser than the isochemical mixed oxides. These experiments are the first demonstration of static high pressure phase transformations in silicate garnets and the first examples of a pure silicate existing in the perovskite structure.