Effects of Fe and Ni Co-Doping on the Optical Properties of TiO2 Thin Films.

In this work, the effects of Fe/Ni co-doping on structural and optical properties of TiO2 thin films were investigated by the X-ray diffraction, scanning electron microscope and UV-visible spectroscopy. The optical properties of transmittance, extinction coefficient, refractive index, real and imaginary parts of dielectric constant of the thin films, prepared by spray pyrolysis, revealed that the absorption in visible region increases due to the influence of Fe/Ni co-doping. The widening of the gap energies is observed as a result of doping. The increased optical gap as a consequence of doping can be explained by decreasing the size of nanoparticles, as confirmed by SEM and increasing the formation of oxygen vacancies as a result of Ni 2 + substitution to Ti 4 + and appearance of the Burstein–Moss effect. [ABSTRACT FROM AUTHOR]