Thermoelasticity of MgO at High Pressures
- Received Date: 2006-06-08
Abstract: The thermoelastic properties of MgO over a wide range of pressure and temperature are studied using the first-principles plane wave pseudopotential method within the generalized gradient approximation. It is shown that MgO remains in the B1 (NaCl) structure at all pressures existing within the Earth, and transforms into the CsCl-type structure at 397 GPa. The athermal elastic moduli of MgO are calculated, as a function of pressure up to 150 GPa. The calculated results are in excellent agreement with experimental data at zero pressure and compare favorably with other pseudopotential predictions over the pressure regime studied. MgO is found to be highly anisotropic in its elastic properties, with the magnitude of the anisotropy first decreasing between 0 and 20 GPa and then increasing from 20 GPa to 150 GPa. The Cauchy condition is found to be strongly violated in MgO, reflecting the importance of noncentral many-body forces. The thermodynamic properties of MgO are consistent with the experimental data at ambient condition.
|Citation:||Zi-jiang Liu, Xiao-wei Sun, Su-hong Ge, Hai-ying Wu, Xiu-lu Zhang, Xiang-dong Yang. Thermoelasticity of MgO at High Pressures[J]. Chinese Journal of Chemical Physics , 2007, 20(1): 65-70. doi: 10.1360/cjcp2007.20(1).65.6|