Structural, electronic, optical and thermoelectric properties of LaMO₃ (M = Ga or In) cubic perovskites: DFT study

Abstract

In this work, we present theoretical calculations of the structural, electronic, optical and thermoelectric properties of the perovskite oxides LaMO 3 (M = Ga or In) using density functional theory (DFT) with GGA–PBE approximation, as implemented in the ABINIT code. The cubic crystal structure of LaMO 3 (M = Ga or In) compounds changes and its volume increases when the Ga atom is replaced by an In atom. In addition, negative formation energies suggest the thermodynamic stability of the studied compounds. Electron charge densities reveal an ionic bond between La and O, while the bond between M and O appears covalent. Electronic properties showed the indirect semiconducting behavior of LaGaO 3 and LaInO 3 perovskites. The calculated indirect bandgaps [Formula: see text] (R–[Formula: see text]) are found to be 3.34[Formula: see text]eV for LaGaO 3 and 2.08[Formula: see text]eV for LaInO 3 . In addition, optical characteristics are determined in terms of real [Formula: see text]([Formula: see text]) and imaginary [Formula: see text]([Formula: see text]) parts of dielectric constant [Formula: see text], refractive index [Formula: see text], absorption coefficient [Formula: see text], reflectivity [Formula: see text], energy loss function [Formula: see text], optical conductivity [Formula: see text] and transmittance [Formula: see text] are also studied. Optical absorption of light energy has been observed in both the visible and ultraviolet ranges, increasing the importance of the studied materials for optoelectronic applications. Finally, the thermoelectric performance of LaMO 3 (M = Ga or In) materials has been explored using the Boltzmann transport theory implemented in the BoltzTraP software package.