| Abstract: The geometric structures, formation energies, electronic structures and magnetic properties of Ni-doped anatase, with different concentrations and doping methods, were studied by the first principle method under the framework of the spin density functional theory, combined with the crystal field theory. The results of formation energy calculation show that the oxygen environment, in the process of crystal growth, has an important influence on the structures of Ni-doping. Analysis of the state density and energy level track map showed that the valence states of Ni ion was different in different doping conditions. Impurity energy levels in the bandgap of all kinds of doping system are formed by the hybridization of Ni3d－O2p. When a doping Ni ion substitute lattice Ti, that will make the unit cell volume and the crystal stability decrease, absorption spectrum red shift, the system is paramagnetic. Interstitial Ni doping makes the unit cell volume increase, the absorption spectrum blue shift, and enables the band to move in the direction of low energy. At this time, the carrier occur n type-degeneration, the ability, of some Ti ions, of losing electrons declined, resulting in the making of Ti3 ions, the system has magnetism. |
