Single-crystal hydrostatic compression of synthetic pyrope, almandine, spessartine, grossular and andradite garnets at high pressures
Single-crystal hydrostatic compression of synthetic pyrope, almandine, spessartine, grossular and andradite garnets at high pressures
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DOI：
10.1007/s002690050240
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发表时间：
1999-11
影响因子：
1.4
通讯作者：
Li Zhang;H. Ahsbahs;Ali Kutoglu;C. Geiger
中科院分区：
文献类型：
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作者：
Li Zhang;H. Ahsbahs;Ali Kutoglu;C. Geiger
通过将晶体一起装入金刚石砧室中，研究了合成镁铝榴石 Mg3Al2(SiO4)3、铁铝榴石 Fe3Al2(SiO4)3、锰铝榴石 Mn3Al2(SiO4)3钙铝榴石 Ca3Al2(SiO4)3 和红铁榴石 Ca3Fe2(SiO4)3 的压缩。使用氖作为压力传输介质，通过高达 15 GPa 的 X 射线衍射确定晶胞参数作为压力的函数。使用氦气作为压力介质，测得镁铝榴石和铁铝榴石的晶胞参数分别高达 33 和 21 GPa。通过将体积数据拟合到三阶 Birch-Murnaghan 状态方程，同时确定所有五种石榴石的体积模量 KT0 及其一阶压力导数 KT0'。通过比较石榴石对之间的体积压缩，可以进一步限制这两个参数，对于镁铝榴石，KT0和KT0'171(2) GPa和4.4(2)，铁铝榴石为185(3) GPa和4.2(3)，锰铝榴石为189(1) GPa和4.2，钙铝榴石为175(1) GPa和4.4， 157(1) GPa 和 5.1 对于钙铁矿，其中对于锰铝榴石、钙铝榴石和钙铁矿来说，KT0′是固定的。直接比较在高压下确定的石榴石对之间的晶胞体积，揭示了镁铝榴石中 8 重协调的三角形十二面体中 Mg2+ 的异常压缩行为。这与之前关于高压下 6 重配位多面体中 Mg2+ 压缩行为的研究一致。结果表明，石榴石不遵循简单的体积模量-体积系统学。
The compression of synthetic pyrope Mg3Al2(SiO4)3, almandine Fe3Al2(SiO4)3, spessartine Mn3Al2(SiO4)3grossular Ca3Al2(SiO4)3and andradite Ca3Fe2(SiO4)3was studied by loading the crystals together in a diamond anvil cell. The unit-cell parameters were determined as a function of pressure by X-ray diffraction up to 15 GPa using neon as a pressure transmitting medium. The unit-cell parameters of pyrope and almandine were measured up to 33 and 21 GPa, respectively, using helium as a pressure medium. The bulk moduli,KT0, and their first pressure derivatives,KT0′, were simultaneously determined for all five garnets by fitting the volume data to a third order Birch-Murnaghan equation of state. Both parameters can be further constrained through a comparison of volume compressions between pairs of garnets, giving forKT0andKT0′171(2) GPa and 4.4(2) for pyrope, 185(3) GPa and 4.2(3) for almandine, 189(1) GPa and 4.2 for spessartine, 175(1) GPa and 4.4 for grossular and 157(1) GPa and 5.1 for andradite, where theKT0′are fixed in the case of spessartine, grossular and andradite. Direct comparisons of the unit-cell volumes determined at high pressures between pairs of garnets reveal anomalous compression behavior for Mg2+in the 8-fold coordinated triangular dodecahedron in pyrope. This agrees with previous studies concerning the compression behaviors of Mg2+in 6-fold coordinated polyhedra at high pressures. The results show that simple bulk modulus–volume systematics are not obeyed by garnets.