Influence of zinc ferrite doping on the optical properties and phase transformation of titania powders prepared by sol–gel method

Zinc ferrite-doped TiO2 nanopowders with various amount of zinc ferrite were prepared by sol–gel method. The effect of zinc ferrite doping on the optical properties and on the anatase-to-rutile phase transformation of TiO2 were reported. X-ray diffraction (XRD) results show that zinc ferrite can prevent the transformation of titania from anatase-to-rutile when the content of zinc ferrite is above 0.5 at.%; while the phase transformation is promoted when the content of zinc ferrite is below 0.5 at.%. Diffuse reflectance spectroscopy (DRS) results show that the absorption edge of zinc ferrite-doped TiO2 has moved to the visible spectrum range, and a very large redshift occurs with increasing the amount of zinc ferrite in comparison with the undopd titania. The proposed mechanisms for the large redshift are discussed.