Investigation on bismuth-based oxide perovskites MBiO3 (M = Rb, Cs, Tl) for structural, electronic, mechanical and thermal properties

Abstract

Herein, we report our density functional theory calculations for structure, electronic, thermodynamic and mechanical properties of MBiO3 (M = Rb, Cs, Tl), compounds of perovskites oxide family. Exchange-correlation potential was treated with generalized gradient and local density approximations. From available ionic data, the tolerance factors and lattice constants were calculated. The values of tolerance factors provided the stability guarantee of MBiO3 compounds in cubic phase while the obtained lattice constants are in accordance to the available data. The cubic phase stability was further confirmed from elastic constants. The electronic structure results disclosed these materials as metallic. Mechanically, all the three perovskites were found as brittle from Cauchy’s pressure, Pugh ratio and Poisson’s ratio. The thermodynamic calculations have been performed using quasi-harmonic Debye model. Thermal properties like Debye temperature, specific heat capacity and thermal expansion have been presented with the variation of temperature and pressure.