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

In this work, we present theoretical calculations of the structural, electronic, optical and thermoelectric properties of the perovskite oxides LaMO3 (M = Ga or In) using density functional theory (DFT) with GGA-PBE approximation, as implemented in the ABINIT code. The cubic crystal structure of LaMO3 (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 LaGaO3 and LaInO3 perovskites. The calculated indirect bandgaps Eg (R-Gamma) are found to be 3.34eV for LaGaO3 and 2.08eV for LaInO3. In addition, optical characteristics are determined in terms of real epsilon(1)(omega) and imaginary epsilon(2)(omega) parts of dielectric constant epsilon(omega), refractive index n(omega), absorption coefficient alpha(omega), reflectivity R(omega), energy loss function L(omega), optical conductivity sigma(omega) and transmittance T(omega) 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 LaMO3 (M = Ga or In) materials has been explored using the Boltzmann transport theory implemented in the BoltzTraP software package.