Influence of calcination temperature on the physical properties of nano-titania prepared by sol-gel/hydrothermal method

Nano-sized TiO 2 powders were synthesized by a modified hydrolysis reaction using titanium butoxide as a precursor, water as a solvent, acetylacetone to slowdown the hydrolysis and the condensation reactions and ammonia as a base catalyst. Phase transformation and particle size of the calcined powders were investigated as a function of the calcination temperature by room-temperature X-ray diffraction; scanning electron microscopy and Fourier transform infrared spectroscopy techniques. Thermal gravimetric analysis (TGA) was used to examine the thermal properties of the produced TiO 2 nanoparticles. The XRD showed that the uncalcined sample was mostly the anatase phase with some rutile content. It was indicated that the thermal annealing resulted in increasing the average crystallite size from 8.2 to 53.5 nm. As the calcination temperature increased, the particle size, the rutile phase, the crystallization of the anatase phase, and the agglomeration were increased. The increase in the rutile content and grain growth are caused by the calcination at higher temperatures even calcination at 800°C for 2 h.