The stability of the hydroxylated (0001) surface of α-Al2O3

Self-consistent density functional calculations of the hydroxylated (0001) corundum surfaces are presented. It is demonstrated that the hydroxylated surfaces are the most stable under most, but not all, conditions. Hydroxylation significantly lowers the surface free energy of α-alumina. The stability of the hydrated surface resolves the discrepancies between the morphology of the α-alumina (0001) surface observed under ultra-high vacuum, and at ambient conditions. A method for the calculation of the equilibrium surface stoichiometry is proposed. The proposed approach provides a valuable connection between theoretical calculations and experiments with metal oxides.