Influence of annealing temperature on the structure and optical properties of TiO2 nanoparticles

The effect of annealing temperature on structure and optical properties of TiO2 nanoparticles prepared by thermal evaporation was investigated. Nanoparticles were annealed with O-2 for 2h at different temperatures from 300 degrees C-900 degrees C. The optical constants were deduced by using effective medium approximation (EMA). Polycrystalline nanoparticles with rutile crystal structure, as evidenced from X-ray diffraction pattern, were obtained with major refraction along (110). Refractive index decreases with decreasing annealed temperature. The direct energy band gap increases with decreasing annealed temperature and decreasing grains size.