A DFT study of structural and electronic properties of cubic thallium based fluoroperovskites TlBF3 (B[dbnd]Ge,Sn,Pb,Zn,Cd,Hg,Mg,Ca,Sr,Ba)

Abstract

This study aims to use Density Functional Theory (DFT) to investigate structural and electronic properties of cubic fluoroperovskites TlBF3 (B = Ge, Sn, Pb, Zn, Cd, Hg, Mg, Ca, Sr, and Ba). The calculation was performed using the Quantum Espresso package using GGA-PBE functional. The optimized lattice parameters for the perovskites ranged from 4.01 Å to 5.08 Å while direct and indirect band gaps were observed, with band gaps between 0.75 eV and 4.48 eV. Results were in good agreement with other theoretical studies using different functionals and packages. It was also found that for all compounds analyzed separately based on three different columns of the periodic table, the larger the atomic radii of the B cations, the larger their equilibrium lattice constants. In addition, an increase in the electronegativity of cations leads to a decrease in covalent character of B–F bonds while Tl–F bond is mainly ionic for all compounds.