Prediction of structural, electronic, mechanical, thermal, and thermoelectric properties in PbMO₃ (M = Sb, Bi) perovskite compounds: a DFT study

Abstract

In the present work, we have presented the structural, mechanical, electronic, thermodynamic and thermoelectric properties of PbMO₃ (M = Sb, Bi) compounds using different exchange–correlation potentials, i.e. with generalized gradient and local density approximations in the framework of density functional theory. The tolerance factors and lattice constants have been computed using the available ionic data. The formation energy, cohesive energy, and tolerance factors have been determined to ensure the stability of PbMO₃ (M = Sb, Bi) compounds in cubic phase. It is found from our calculated results that the computed lattice constants are consistent with the available data. The elastic constants are also calculated and satisfy the cubic phase stability criteria. The electronic band profiles illustrate their metallic nature. According to the computed values of the Cauchy's pressure, Pugh's ratio, and Poisson's ratio, the considered perovskites are mechanically brittle. Further, the thermodynamic behaviour of these materials shows that the variation of temperature affects thermal parameters such as Debye temperature, specific heat capacity, and thermal expansion. Furthermore, transport characteristics, for instance, Seebeck coefficient, electrical conductivity, thermal conductivity and figure of merit, have also been computed under temperature.