High-pressure single-crystal structural analysis of AlSiO3OH phase egg
High-pressure single-crystal structural analysis of AlSiO3OH phase egg
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DOI：
10.2138/am-2018-6562
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发表时间：
2018-11
影响因子：
3.1
通讯作者：
K. Schulze;M. Pamato;A. Kurnosov;T. B. Ballaran;K. Glazyrin;A. Pakhomova;H. Marquardt
中科院分区：
文献类型：
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作者：
K. Schulze;M. Pamato;A. Kurnosov;T. B. Ballaran;K. Glazyrin;A. Pakhomova;H. Marquardt
摘要我们提出了单晶相卵AlSiO_3 OH的第一状态方程和高压下的结构修正。相蛋是Al 2 O3-SiO2-H2O系统的一员，其中包含可能沿典型地幔地热沿着稳定的相（Fukuyama et al. 2017），并且是水输送到地球深部地幔的良好候选者。单晶同步辐射X射线衍射在高达23 GPa的压力下进行。我们观察到B轴是最可压缩的方向，B角减小到16 GPa，然后保持恒定在~97.8°的值，直到达到最大实验压力。在低压下进行的结构细化揭示了一个扭曲的八面体周围的硅原子由于六个Si-O键长之一显着大于其他五个。这种特定的Si-O 4键的长度随着压力的增加而迅速减小，导致在16 GPa以上的压力下形成更规则的八面体。我们确定了Si-O 4键的缩短和八面体单元之间的空位的收缩，其中氢原子被认为是AlSiO 3OH相蛋的压缩机制的主要组成部分。
Abstract We present the first equation of state and structure refinements at high pressure of single-crystal phase egg, AlSiO3OH. Phase egg is a member of the Al2O3-SiO2-H2O system, which contains phases that may be stable along a typical mantle geotherm (Fukuyama et al. 2017) and are good candidates for water transport into Earth’s deep mantle. Single-crystal synchrotron X‑ray diffraction was performed up to 23 GPa. We observe the b axis to be the most compressible direction and the b angle to decrease up to 16 GPa and then to remain constant at a value of ~97.8° up to the maximum experimental pressure reached. Structure refinements performed at low pressures reveal a distorted octahedron around the silicon atom due to one of the six Si-O bond lengths being significantly larger than the other five. The length of this specific Si-O4 bond rapidly decreases with increasing pressure leading to a more regular octahedron at pressures above 16 GPa. We identified the shortening of the Si-O4 bond and the contraction of the vacant space between octahedral units where the hydrogen atoms are assumed to lie as the major components of the compression mechanism of AlSiO3OH phase egg.