Internally consistent thermodynamic data and equilibrium phase relations for compounds in the system MgO‐SiO₂ at high pressure and high temperature

Abstract

Thermochemical and thermophysical data for phases in the system MgO‐SiO 2 are critically evaluated, refined, and supplemented by calculating phase equilibrium relations from the available calorimetric data. Lattice vibrational models are used to constrain further the entropies and heat capacities. Phases in the data base are MgO, SiO 2 (coesite, stishovite), Mg 2 SiO 4 (olivine, ß‐phase, spinel), and MgSiO 3 (pyroxene, garnet, ilmenite, and perovskite). The internally consistent data set reproduces the experimentally determined phase relations in the system at pressures to 30 GPa and to melting temperatures.