Electronic structure, mechanical, optical and thermodynamic properties of cubic perovskite InBeF3 with pressure effects: First-principles calculations

The electronic structure, mechanical, optical and thermodynamic properties of cubic fluoroperovskite InBeF3 under high pressure were studied for the first time. The lattice parameter of the optimized InBeF3 crystal is 3.853 & ANGS;, which agrees well with the literature value (3.846 & ANGS;). The calculated phase transition point of InBeF3 is about 28.1 GPa. The band structure analysis show that the InBeF3 is an indirect band gap semiconductor (Eg = 2.226 eV) at zero pressure, and the band gap decreases as the pressure increases. Yet the form of its band gap does not change, and the value of band gap is always in the visible region under the pressure. In addition, the electronic structure of InBeF3 crystal is calculated by hybrid functional HSE06. It is found that the application of hybrid functional does not have much effect on the electronic structure of InBeF3. The valence bands of InBeF3 are mainly composed of the 4d orbital electrons of In and the 2 s orbital and 2p orbital electrons of F. The optical properties of InBeF3 crystal were further investigated. The absorption edge and static refractive index for InBeF3 at 0 GPa are 0.59 eV and 2.19, respectively. The peaks of all optical spectral increase as the pressure increase. Additionally, the relative volume, heat capacity, thermal expansion coefficient and Debye temperature of InBeF3 crystal were studied. The results of this paper show that the InBeF3 crystal has good absorption in the ultraviolet region and is potential candidate material in optical and ultraviolet devices.