Electronic structure and bandgap of γ-Al2O3 compound using mBJ exchange potential
Department of Physics, Faculty of Science, University of Isfahan (UI), Hezar Gerib Avenue, Isfahan, 81744, Iran
Nanoscale Research Letters 2012, 7:488 doi:10.1186/1556-276X-7-488Published: 31 August 2012
γ-Al2O3 is a porous metal oxide and described as a defective spinel with some cationic vacancies. In this work, we calculate the electronic density of states and band structure for the bulk of this material. The calculations are performed within the density functional theory using the full potential augmented plan waves plus local orbital method, as embodied in the WIEN2k code. We show that the modified Becke-Johnson exchange potential, as a semi-local method, can predict the bandgap in better agreement with the experiment even compared to the accurate but much more expensive green function method. Moreover, our electronic structure analysis indicates that the character of the valence band maximum mainly originates from the p orbital of those oxygen atoms that are close to the vacancy. The charge density results show that the polarization of the oxygen electron cloud is directed toward aluminum cations, which cause Al and O atoms to be tightly connected by a strong dipole bond.