Post-perovskite phase in selected sesquioxides from density-functional calculations

We search for the existence of the post-perovskite structure in several nonmagnetic M2O3 sesquioxides using density-functional calculations. For each material we consider the corundum, Rh2O3-type II, perovskite, and post-perovskite structures. The perovskite structure is unstable with respect to at least one of the other structures at all pressures for all materials. The post-perovskite structure is stable above 120 GPa in Al2O3, above 344 GPa in Rh2O3, above 136 GPa in Ga2O3, and above 47 GPa in In2O3.