Elastic and structural properties of β-Ga2O3 and α-Ga2O3 are investigated from first principles. The full elastic tensors and elastic moduli of both phases at 0 K are computed in the framework of semi-local density-functional theory. We determine mechanical instabilities of β-Ga2O3 by evaluating the full stiffness tensor under load for a range of hydrostatic pressure values. While a phase transition from the β to α phase is found to be energetically favored at 2.6 GPa, we show that the β phase is only mechanically unstable for much higher pressures (>30 GPa), which agrees well with experimental results. Our employed approach is based on the Born stability criterion, is independent of crystal symmetry, and thus can be readily applied to different materials.
@article{arxiv.2112.01843,
title = {Elastic stability of Ga$_2$O$_3$: Addressing the $\beta$ to $\alpha$ phase transition from first principles},
author = {Konstantin Lion and Pasquale Pavone and Claudia Draxl},
journal= {arXiv preprint arXiv:2112.01843},
year = {2022}
}