Study of structural transformation in TiO2 nanoparticles and its optical properties

Pure and mixed phase TiO2 have been prepared by sol-gel method; calcinated at four different temperatures. The influence of calcination temperature on crystallite size, morphology, band gap and luminescence properties of resultant material have been investigated. Different trends were observed in the phase transformation, particle growth, shift in energy band gap and in luminescence with the change in tensile strain to compressive strain of the prepared TiO2 nanomaterial. X-ray diffraction (XRD) showed that prepared nanocrystals have pure anatase and anatase-rutile mixed structures. The prepared samples having crystallite size between 19 nm to 68 nm were observed at different calcination temperatures. Williamson-Hall plot results indicate the presence of tensile strain at 400, 500 and 600 degrees C while compressive strain at 700 degrees C. Scanning electron microscopy (SEM) shows that the particles are non-uniform. Ultraviolet-Visible spectroscopy (UV-Vis) is used to calculate the energy band gap of materials and it has been observed that the band gap decreases with increase in temperature. Fourier transform infrared spectroscopy (FTIR) describes local environment around TiO2 nanoparticles. Photoluminescence spectroscopy (PL) exhibits the change in PL intensity with phase change and different trends have been observed in emission edges. (C) 2012 Elsevier B.V. All rights reserved.