Abstract
This research presents the structural, optical, elastic, and electronic properties of cubic Barium-based halide-Perovskites in combination with Al and Tl elements of the form XBaF3 (X = Al and Tl). The density functional theory with the generalized gradient approximation of Perdew-Burke-Ernzerhof and the Trans-Blaha modified Becke Johnson (TB-mBJ) approximation are employed for the consideration of exchange-correlation effects. Structurally these compounds are found to be cubic with a space group of Pm-3 m (#221). The computed band's structure with TB-mBJ confers precise electronic properties of these materials as it is a precise and accurate approximation for bands structure prediction. The computation of bands structure for both the materials reveals a semiconducting nature having a direct bandgap from X to X (X-point in the reciprocal lattice space to X-symmetry points), having values lying from 0 eV at Fermi level to 3.75 eV for TlBaF3 and 4.36 eV for AlBaF3. The total and partial densities of states, as well as their contribution to the different bands, are investigated and evaluated, i.e. total density of state and partial density of state are exploited. The IRelast package is used to calculate the elastic constants of these crystals, with cubic symmetries, which can then be used to explore elastic and mechanical characteristics. Elastic properties show that the compounds of interest are mechanically stable, anisotropic, and ductile. Besides this, due to the high value of shear modulus 'G,' these materials demonstrate resistance to plastic deformation. It is noticed that these compounds are transparent for incident photons based on their optical properties. Based on these interesting investigations of different physical properties for XBaF3 (X = Al and Tl), we have selected these materials and to our best understanding, this is the first comprehensive theoretical computation of these compounds which presents structural, optical, electronic, and elastic properties that have yet to be confirmed experimentally.