Phase stability and elastic properties of CuGaSe2 under high pressure

Abstract

We report stability of high pressure phases and elastic properties in CuGaSe2, especially in cubic and orthorhombic phases. The distorted structures from Fm3¯m and Cmcm consist of Pmmn, P21/m, Amm2 and P4/mmm were observed. Cu and Ga sites in Fm3¯m and Cmcm can distinguish in the lower symmetry space groups which are P4/mmm and Amm2, respectively. The enthalpy differences of an interested structure are compared in the pressure range 0–100 GPa. The phonon dispersion relation of CuGaSe2 was studied, and found that the P4/mmm and Amm2 space groups give stability of phonon vibration modes. Moreover, we observe chemical bonds and elastic properties of CuGaSe2 at high-pressure conditions. Elastic constants indicate mechanical stability of CuGaSe2 in P4/mmm and Amm2 phases. Although CuGaSe2 has become nonsemiconductor material in the P4/mmm and Amm2 phases, the strong of covalent bonds and sharing electrons are still increased by high pressure effect.