DFT based computational investigations of the physical properties of perovskites-structure SrXO3 (X = Si, Tb, Th) for optoelectronic and thermo-mechanical applications

Abstract

Density Functional Theory (DFT) method is employed for investigating the structural, elastic, electronic, optical, and thermal properties of Perovskite structure SrXO3 (X = Si, Tb, and Th). The studied lattice parameters show good agreement with the previous theoretical and experimental results. The elastic stiffness constants, (Cij) of SrSiO3, SrTbO3, and SrThO3 satisfied the born stability criteria which confirm the mechanical stability of these phases. It is observed that when Tb or Th is replaced with Si, the brittleness behaviours of SrTbO3 or SrThO3 change to ductility, which improves its machinability for industrial applications. The investigation of anisotropic factors of SrSiO3, SrTbO3, and SrThO3 ensured that SrSiO3 is more anisotropic than SrTbO3 and SrThO3. By evaluating the electronic properties, it can be advantageous for applying the topological insulators (TI), solar cells, or PV (Photovoltaic) cell fabrication. Furthermore, the optical properties are studied and detail discussed with SrXO3 (X = Si, Tb, and Th). The reason of low Debye temperature (ΘD) and low minimum thermal conductivity (Kmin) has been perfectly explicated through the consideration of the mean atomic weight (M/n) of the compounds. Temperature-dependent of heat capacities (Cv, Cp) and linear thermal expansion coefficient (α) are also estimated using the quasi-harmonic Debye model and discussed. The SrTbO3 and SrThO3 compounds can be employed as potential thermal barrier coating (TBC) materials for high-temperature applications, according to the low values of Kmin, ΘD and α.