Optical and structural properties of Fe–TiO2 thin films prepared by sol–gel dip coating

In this study, the optical and structural properties of an Fe–TiO2 sol were investigated. TEOT[Ti(OC2H5)4] and ferric nitrate[Fe(NO3)3
• 9H2O] were used as precursors to make the Fe–TiO2 sol. The samples for measurement were prepared on a glass substrate using the sol–gel dip coating method. The annealing temperature (Ta) was varied in the range of 673.15–873.15 K in intervals of 50 K. The cut-off points of the samples were increasingly red-shifted with increasing Fe content. Simultaneously, the optical band gap decreased from 4.03 to 3.64 eV. A change of the crystalline phase as the Fe content increased was observed from the X-ray diffraction measurements. Combined with the X-ray diffraction analysis, the observed variations in both the cut-off points and optical band gap were directly correlated with the structural change of the composite films.