First principles study of the structure, mechanical and optical properties of cubic perovskite NaCaCl3 under pressure

Based on the first-principles methods, the electronic, mechanical and optical properties of NaCaCl3 crystal were investigated under various pressures for the first time. At 0 GPa, the lattice constant and bulk modulus were calculated to be 5.278 Å and 27.011 GPa, respectively. Analysis of Poisson's ratio and Pugh's ratio indicated that NaCaCl3 exhibits ductile characteristics, which increases with the increasing pressure. Based on the crystal mechanical stability condition, the phase transition pressure of NaCaCl3 was calculated to be 5.12 GPa. The electronic property demonstrated that NaCaCl3 exhibits an indirect and wide band gap insulator (3.84 eV) at 0 GPa, and the band gap increases with the increasing pressure. The results of optical properties show that all spectrums of NaCaCl3 exhibit a blue shift when the pressure increases. The excellent ultraviolet absorption suggests that NaCaCl3 has a potential application in vacuum ultraviolet devices. And it is also suitable as transparent coating and window materials in the infrared and visible regions due to small reflectivity and absorption.