Study of the thermodynamic properties of SrTiO3 perovskite by the statistical moment method with improved interatomic potential

Abstract

We study the thermodynamic properties of cubic SrTiO3 perovskite going beyond the statistical moment method within approximation up to the fourth-order of the power moments of the atomic displacements. The analytic expressions of the thermodynamic quantities, such as the free energy, thermal expansion coefficients, and heat capacity at the constant volume and constant pressure of SrTiO3, are obtained. The potential with the partial charge model and functions of Demontis and Pedone is used to calculate the numerical thermodynamic quantities of SrTiO3 from room temperature up to high temperature. The numerical results of the thermodynamic quantities of SrTiO3 by the statistical moment method are in good agreement with the previous theoretical and experimental results for a wide temperature range. Our research also shows that the anharmonic effects of the lattice fluctuations affect the thermodynamic properties of SrTiO3 dominantly. It has a good potential to develop the statistical moment method for investigating the temperature effects on the thermodynamic quantities of the perovskite–structure materials.