HIGH-PRESSURE CRYSTAL-CHEMISTRY OF SPINEL (MGAL2O4) AND MAGNETITE (FE3O4) - COMPARISONS WITH SILICATE SPINELS
HIGH-PRESSURE CRYSTAL-CHEMISTRY OF SPINEL (MGAL2O4) AND MAGNETITE (FE3O4) - COMPARISONS WITH SILICATE SPINELS
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DOI：
10.1007/bf00308271
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发表时间：
1986-01-01
影响因子：
1.4
通讯作者：
HOFMEISTER, AM
中科院分区：
文献类型：
--
作者：
FINGER, LW;HAZEN, RM;HOFMEISTER, AM
本文用X射线衍射法测定了镁铝尖晶石及其类质同象磁铁矿Fe_3O_4的高压晶体结构和压缩率。测得尖晶石和磁铁矿（假定K′=4）的体积模量K分别为1.94±0.06和1.86±0.05 Mbar，与以前的超声波测定结果雅阁。的氧的参数，唯一的可变的原子位置坐标的尖晶石结构（Fd 3 m，Z=8），随着压力的MgAl 2 O 4，从而表明镁四面体比铝八面体更可压缩。在磁铁矿中，u参数不变，四面体和八面体都表现出1.9Mbar的整体体积模量特征。这种行为与硅酸镍尖晶石（γ-Ni 2SiO 4）形成对比，后者的u参数随压力增加，因为硅四面体与镍八面体相比相对不可压缩。
High-pressure crystal structures and compressibilities have been determined by x-ray methods for MgAl2O4spinel and its isomorph magnetite, Fe3O4. The measured bulk moduli, K, of spinel and magnetite (assuming K′=4) are 1.94±0.06 and 1.86±0.05 Mbar, respectively, in accord with previous ultrasonic determinations. The oxygenuparameter, the only variable atomic position coordinate in the spinel structure (Fd3m,Z=8), decreases with pressure in MgAl2O4, thus indicating that the magnesium tetrahedron is more compressible than the aluminum octahedron. In magnetite theuparameter is unchanged, and both tetrahedron and octahedron display the 1.9 Mbar bulk modulus characteristic of the entire crystal. This behavior contrasts with that of nickel silicate spinel (γ-Ni2SiO4), in which theuparameter increases with pressure because the silicon tetrahedron is relatively incompressible compared to the nickel octahedron.