First-principles calculations for the structural, elastic and thermodynamic properties of cubic perovskite BaHfO₃under pressure

Abstract

The structural, single-crystal and polycrystalline elastic and thermodynamic properties of cubic perovskite BaHfO3 under pressure were investigated using the first-principles total energy calculations in the frame of the generalized gradient approximation (GGA) combined with the quasi-harmonic Debye model in which the phonon effects are considered. The calculated ground-state quantities, such as the lattice constant, Young's modulus, shear modulus, shear and longitudinal sound velocities and Debye temperature, were in reasonable agreement with previous theoretical and experimental data. Based on the elastic constants, bulk modulus, shear modulus and Young's modulus, the structural stability, hardness, stiffness and the brittle and ductile behaviors, along with the binding characteristic of BaHfO3 under pressure effects, have been discussed. More importantly, the temperature and pressure dependencies of the lattice constant, bulk modulus, the Debye temperature, heat capacities, volume expansion coefficient and lattice thermal conductivity are predicted successfully in the wide temperature and pressure ranges. It was found that the effects of pressure and temperature are inversely proportional. The obtained specific heat capacities at constant pressure, at the thermal expansion coefficient and at the thermal conductivity match well with the experimental data available in the range of 300–1300 K.