Monodispersibility and size control in the preparation of spherical titania particles by thermal hydrolysis of TiCl₄ in various solvents

Spherical anatase TiO₂ particles were successfully synthesized by the thermal hydrolysis of TiCl₄ in various solvents. In the case of n-propanol, isopropanol, and acetone with an RH ratio of 3, spherical titania particles were produced. In contrast, spherical TiO₂ particles did not form in methanol and ethanol because of their high dielectric constants. In this study, different oscillators (an oven, and isothermal and ultrasonic oscillators) were used to prepare titania prior to studying the morphology and particle size. The spherical TiO₂ particles prepared using the ultrasonic oscillator were much smaller than those obtained using the other heating methods, because of the lower temperature gradient in the solution; however, a narrower size distribution of particles was observed in the TiO₂ prepared in an oven. The presence of acetylacetone as a dispersing agent in the starting solutions significantly reduced the particle size. The optimum concentration of acetylacetone of 0.8 mg/cm³ resulted in more uniform TiO₂ spheres with an average particle size of 1.4 µm.