First-principles study of γ-Al2O3 (100) surface

The atomic and electronic structures of the {gamma}-Al{sub 2}O{sub 3} (001) surface are studied using the density-functional theory approach. From calculated surface energies for different surface terminations, we identified a mixed dense Al-O (001) layer, containing both octahedral aluminum and oxygen atoms, as the most stable {gamma}-Al{sub 2}O{sub 3} (001) surface. We found that environmental O{sub 2} gas does not affect the surface stoichiometry. Comparison of the electronic structure of the surface and the bulk {gamma}-Al{sub 2}O{sub 3} shows that the band gap at the surface is slightly smaller than that of the bulk {gamma} alumina due to the contributions of the surface O 2p states.