Effect of Ni Doping on the Structural and Optical Properties of TiO2 Nanoparticles at Various Concentration and Temperature

TiO2 nanopowders doped by Ni were prepared by sol–gel method. The effects of Ni ion (transition metal ion) doping on the physical structural and optical properties of TiO2 have been investigated by X-ray diffraction (XRD), scanning electron microscopy and UV–Vis absorption spectroscopy. XRD results suggest that adding impurities has a significant effect on anatase phase stability, crystallinity, and particle size of TiO2. The phase transformation from anatase to rutile was inhibited by Ni ion doped TiO2 at temperatures 675 °C. The lowest band gap value (2.83 eV) was obtained for TiO2-4%Ni sample calcined at 675 °C.