Electronic Structure of Titanium Dioxide Doped with Nickel and Chromium Atoms

Changes in the band gap and density of electronic states of titanium dioxide upon doping with transition metals Ni and Cr, as well as codoping with Ni/Cr–TiO 2 , are studied by the density functional method in the LDA + U approximation. It is shown that, upon doping with TiO 2 in the band gap, local levels of impurity states of chromium and nickel arise. Taking into account the parameters of the Coulomb and exchange interactions allow us to obtain the band gap values of 3.14 eV for anatase, 2.93 eV for the TiO 2 structure doped with nickel atoms, 2.96 eV for the TiO 2 structure doped with chromium atoms, and 2.88 eV for the TiO 2 structure codoped with nickel and chromium atoms, which are in good agreement with the experimental values of 3.20, 2.86, 2.98, and 2.45 eV, respectively.