Prediction of a high-pressure phase transition in Al2O3.

Predicts the occurrence of a phase transition at high pressure from the corundum structure to that of Rh2O3(II). Application of first-principles calculations with linearized, augmentized plane-wave method; Existence of free Al2O3 in deep lower mantle; Effect of transition on fluorescence of ruby and shock resistance tests of Al2O3 as window material.