Electronic and elastic properties of BaLiF3with pressure effects: First-principles study

Abstract

BaLiF3 is an important optical crystal for use as a window material in the ultraviolet region. In this work, we studied the electronic and elastic properties of BaLiF3 with pressure effects by the generalized gradient approximation within the density-functional method. Studies indicate that BaLiF3 is mechanically stable and almost elastically isotropic up to 190 GPa, which is considerably higher than the previously reported value. The changing trends of its elastic constants, bulk modulus, B/G ratio, Poisson ratio, and Debye temperature with pressure were systematically investigated. Electronic property calculations reveal that BaLiF3 is an ionic insulator with a bandgap of 6.14 eV at 0 GPa and the bandgap is formed by Ba-5d states and F-2p states. Two interesting phenomena are found: one is that the bandgap of BaLiF3 first increases and then decreases with increasing pressure and the reason for this is explored. Another is that Li-2s states only appear above the Fermi level in this inverted fluoroperovskite.