Effect of substituted IIIB transition metals on the energy gap of α-Al₂O₃ by first-principle calculations

Self-consistent band structure and density of states calculations were performed for the pure alumina (corundum phase) and the aluminates α-Al_2–x T_x O₃ where T is a transition metal and stands for Sc, Y, La and Ac with x = 0.5. In this study we have employed the full potential linear augmented plane wave (FPLAPW) with generalized gradient approximations (GGA) based on the density functional theory (DFT). The results show that the size of the band gap in these alloys decreases considerably and these reductions are related to the ionic radius of the substituted transition metal. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)