Phase stability and elasticity of Sc2O3 at high pressure

An investigation into the high-pressure behavior of Sc2O3 was conducted using first-principle calculations based on density functional theory within the generalized gradient approximation. Nine candidate phases were considered and simulated, C-, B-, A-RES, Rh2O3(II), Gd2S3, U2S3, Al2Er3, corundum and PPv respectively. Our results demonstrate phase transitions of Sc2O3 from C- to B-RES phase at 15 GPa, then to Gd2S3 phase at 18 GPa. Elastic constants of Sc2O3 present softening from about 270 GPa to 337 GPa, associated with a semiconductor-to-metal crossover. The Gd2S3-type Sc2O3 is both mechanically and dynamical stable at least up to 302 GPa supported by the mechanically stable criteria and the phonon spectrum.