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Prediction of lattice constant, volume and density of perovskite MgSiO3 with cubic structure at high pressure up to 135 GPa and high temperature up to 4000 K from statistical moment method
Nguyen Quang Hoc, Nguyen Khac Phong, Pham Ngoc Hoa, Tran Minh Phuong, Pham Khanh Chi and Le Thi Huong Giang
The analytical expression of the Helmholtz free energy, the mean nearest neighbor distance between two atoms, the lattice constant, the volume and the density for perovskite crystals with cubic structure are derived by using statistical moment method (SMM). The article provides numerical results for the temperature and pressure dependence of the lattice constant, the volume and the density of MgSiO3 perovskite in the temperature range from 0 to 4000 K and in the pressure range from 0 to 135 GPa. Our SMM numerical results for MgSiO3 perovskite are compared with that for CaSiO3 perovskite, experimental data and results calculated by other methods. Our other SMM numerical results are new and predictive of experimental results. This is the first application of SMM to study the structural characteristics of cubic MgSiO3 perovskite under extreme conditions of temperature and pressure. On that basis, this research result can be developed to study the thermodynamic, elastic deformation, elastic wave and melting characteristics of cubic MgSiO3 perovskite.
Keywords: Helmholtz free energy, mean nearest neighbor between two atoms, cubic perovskite, lattice constant, volume, density, MgSiO3, CaSiO3, temperature range from 0 to 4000 K, pressure range from 0 to 135 GPa, SMM
DOI: 10.32908/hthp.v53.1807