The Effect of Cu Doping on the Transformation from Rutile to Anatase and Cu Occupation Tendency in TiO 2 Solid Solution

Abstract

TiO 2 doped with different amounts of Cu 2+ ions (from 0 to 3 mol%) was synthesized by sol-gel method. The samples were characterized by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The XRD analysis showed that the Cu-doped TiO 2 samples exhibit anatase and rutile phases. The lattice parameters remain unchanged, independent of Cu 2+ content. Diameter of TiO 2 increased significantly with increasing concentrations of Cu 2+ . The investigated results indicate that a greater portion of the Cu 2+ ions are well incorporated into the anatase and rutile TiO 2 lattices. The stretching vibration frequencies of the interatomic bonds were calculated by the electronegativity principle. The calculated data were compared with infrared spectra. The results show that in the rutile and anatase phases, O atoms in the TiO 2 lattice and some interstitial Cu atoms form Cu-O bond, and other substitutional Cu that replaces Ti atoms in TiO 2 lattice form Cu-O bond with O atoms in the TiO 2 lattice.