Ab-initio prediction of the mechanical, magnetic and thermoelectric behaviour of perovskite oxides XGaO3 (X = Sc, Ti, Ag) using LDA+U functional: For optoelectronic devices.

ABSTRACT

The mechanical, magnetic and thermoelectric properties of spin polarized XGaO3 (X = Sc, Ti, Ag) perovskite oxides in cubic phase have been investigated using LDA + U functional through ab-initio study based on density functional theory (DFT) in the framework of WIEN2K simulation code. The Full Potential Linearized Augmented Plane Wave (FP-LAPW) technique along with PBE-GGA functional have been used to optimize the systems and determining exchange-correlation potential. However, in order to address on-site self-interactions error and overcome limitations of PBE-GGA functional, LDA + U has been employed because Hubbard parameter 'U' is found an appropriate remedy to consider on-site self-interactions, and to calculate improved electronic energy band gap. All spin polarized band structures reveal indirect band gap with different energies Eg (eV) such as ↑↓ 0.98 eV for ScGaO3, ↑1.05 eV and ↓1.70 eV for TiGaO3, ↑1.13 eV and ↓2.19 eV for AgGaO3. Thus, all compounds are semiconductor in nature. The analysis of spin polarized total and partial density of states unveil that ScGaO3 is non-magnetic material, whereas, TiGaO3 and AgGaO3 are characterized by strong exchange splitting of 3d (Ti) and 4d (Ag) states with significant spin magnetic moments, i.e., 1.0002 µB and -2.0002 µB, respectively. The elastic constants, i.e., Bulk, Young and Shear moduli, Poisson's coefficient, Anisotropy factor, Pugh's ratio, Cauchy pressure and melting temperature are calculated through Viogt-Reuss-Hill approximation. The thermoelectric response of the considered perovskites has been determined through semi-classical Boltzmann transport theory in the framework of BoltzTraP simulation code. Basic understandings of the mechanical, magnetic and thermoelectric properties of these compounds are studied for the first time in this manuscript.