spectrum study of Fe-doped TiO2 nano-particles prepared by sol-gel method

Fe doped TiO2 nano-particles were prepared by sol-gel method. XRD, TEM and UV-Vis diffuse reflectance spectrometry were used to characterize the structure, morphology and optical property, respectively. The average grain size of the synthesized Fe-doped TiO2 powders is in the range of 10-20nm while the crystal size increases with the increasing Fe content. UV-Vis DRS was found to be more sensitive than EXAFS and Mössbauer Spectrometry for detecting weak impurity phase (α-Fe2O3) in TiO2. Few α-Fe2O3 was identified in 1.44wt% Fe-doped TiO2, which indicates the maximum concentration of Fe substituting Ti in TiO2 is below 1.44wt%. Obvious red shift of the absorption edge was observed when Fe doping into TiO2. Both band gap narrowing and color center (oxygen vacancy) are thought to be responsible for the red shift. In addition, the shift of absorption edge of the Fe-doped TiO2 powders with various Fe content is ascribed to size effect.