First-principles calculations to investigate structural, electronics, optical, and mechanical properties of Bi-based novel fluoroperovskites TBiF₃ (T = Hg, Xe) for optoelectronic applications

The present study investigates the structural, electronics, optical, and mechanical properties of bismuth-based novel fluoroperovskites TBiF₃ (T = Hg, Xe) with the help of first-principles calculations. The enthalpy of formation and the phonon spectra are used to determine the thermodynamic stability of cubic fluoroperovskites. The lattice parameters of HgBiF₃ and XeBiF₃ are found 4.78 and 4.82 Å, respectively. Both compounds have a direct band gap showing a semiconducting behavior interpreted with the help of the density of states. HgBiF₃ has a band gap of 2.65 while XeBiF₃ possesses a band gap of 3.12 eV. For an in-depth analysis of the compounds, the optical properties of both materials are investigated. Both materials are found mechanically stable, incompressible, and hard ones according to the mechanical properties. According to Pugh's ratio and Cauchy pressure, HgBiF₃ is found as brittle whereas XeBiF₃ is found as ductile in nature. The combined study of these properties reveals that HgBiF₃ is a preferable dielectric material for optoelectronic applications.