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. (C) 2004 Elsevier B.V. All rights reserved.