Structural and spectroscopic study of Fe-doped TiO2 nanoparticles prepared by sol–gel method

5% (molar ratio) Fe doped TiO2 nanoparticles were prepared by a sol gel method and the post annealing of the samples was carried out at 400 °C, 600 °C and 800 °C in air. Structural characterization of the samples was carried out using High Resolution Transmission Electron Microscopy (HRTEM). HRTEM images of the samples revealed that the mean size of the nanoparticles changed from ∼8 nm to ∼100 nm as the annealing temperature was increased. Experimental investigation of the electronic structure of TiO2:Fe nanoparticles is important in order to understand the correlation between electronic and optical properties in these samples. X-ray Photoemission Spectroscopy (XPS) of the TiO2:Fe nanoparticles was performed to study the electronic structure. The results of XPS study confirmed the presence of Fe in all samples, which could not be detected by HRTEM and XRD, in spite of low doping levels, and revealed that Fe ions are predominantly in Fe3+ states. Photoluminescence (PL) measurements have been measured with an excitation energy of 250 nm to study optical properties of the TiO2:Fe nanoparticles. The active PL band at ∼440 nm has been observed.