Electronic structure of alumina doped by light elements

The results of calculations of electronic structure and magnetic properties of α-Al2O3 doped by light elements (B, C and N) are presented. All calculations were performed within the density functional theory in the coherent potential approximation. Several possibilities of the 6 at. % impurities distribution were considered: nitrogen, carbon and boron impurities (marked as X in the general case) in oxygen sublattice - Al2[O0.98X0.02]3, in interstitials - Al2O3X0.06, both in oxygen sites and interstitials - Al2[O0.99X0.01]3X0.03. For each case, the calculations were performed for nonmagnetic as well as magnetic states of the impurity atoms. It is found that both for substitutional and interstitial impurities all sp-element impurities induce spin-polarized states around the Fermi level and reduce the band gap in Al2O3.