Synthesis of spherical titanium dioxide particles by homogeneous precipitation in acetone solution

Titania powders were synthesized by thermal hydrolysis of titanium tetrachloride in a mixed solvent was studied. The dielectric constant was tuned by regulating the acetone/water volume ratio (R/H ratio) and temperature of the solvent. Hydroxypropyl cellulose (HPC) was used as a steric dispersant. The synthesis were carried out at R/H ratios of 0-4, temperatures of 70-90°C, TiCl₄ concentrations of 0.05-0.2 M, HPC concentrations of 0-5 × 10^-3 g/cm³, and synthesis times of 15-60 min. The TiO₂ particles obtained at an R/H ratio of 0, i.e., pure water system, were fine and agglomerated. In contrast, the TiO₂ particles prepared at an R/H ratio of 3 were uniform and spherical. The TiO₂ particle size increased with increasing TiCl₄ concentration. The synthesis temperature did not influence the particle size, but greatly influenced the morphology of the TiO₂. Adding HPC to the solution yielded more uniform and spherical particles. In addition, the synthesis time should be longer than 30 min to obtain the most uniform and spherical particles. The dielectric constant of the acetone-water mixed solvent at 28 gave the most uniform and spherical TiO₂ particles. The powders prepared at the condition of 0.1 M TiCl₄, R/H ratio of 3, HPC concentration of 0.001 g/cm³, temperature of 70°C, and synthesis time of l h exhibited the most uniform and spherical morphology. The as-synthesized powder was anatase and retained the phase below 400°C. It transformed to the rutile phase after calcination at 700°C.