Effect of synthesis conditions and calcination on structural properties of TiO2 nanoparticles prepared by sol-gel method

In this paper nanoparticles of titanium dioxide have been synthesized by sol-gel method. Effect of sol aging time as well as calcination temperature on physical and structural properties of the nanoparticles have been studied by thermal analysis TG/DTA, x-ray diffraction XRD, transmission electron microscope TEM, and statistical analysis of particle size distribution. DTA thermal analysis of the sample shows three weight-loss regions. XRD analysis shows that samples have anatase phase up to 700 ºC, but at 800 ºC relative phase change to rutile can be seen and nanoparticles have mixed anatase and rutile phases. The samples calcined at 900 ºC have pure rutile phase. The results show that by increasing the calcination temperature the size of nanoparticles has increased and the largest crystallite size for anatase phase is obtained 38.7 nm and 147.5 nm for rutile phase. Furthermore, aging time has no effect on the crystalline phase of samples. FTIR spectra of the samples indicate the formation of Ti-O and O-Ti-O bonds. Absorption peaks which are related to symmetric and asymmetric CO bonds have been reduced after calcination and have been lost at higher temperatures. TEM image confirms the nanoparticles are spherical with 13.2 nm average diameter.