Aerosol synthesis of Ti–O powders via in-droplet hydrolysis of titanium alkoxide

A method to produce Ti–O powders by an in-droplet hydrolysis of metal alkoxide precursor is presented. Titanium n-tetrabutoxide, hydrolysis water, and acetic acid were included in the ethanolic precursor solution that was nebulized. The resulting aerosol was transported to a tubular flow reactor where the ethanol evaporation initiated a polycondensation reaction and solid particles were formed starting from droplet surface. Titanium hydrous oxide particles were obtained at 200°C in atmospheric pressure of nitrogen and air. The collected powders were characterized by XRD, TG–SDTA, BET, SEM, TEM, and IR- spectroscopy, as well as with aerosol impactor. The as-produced powder particles were amorphous, smooth on the surface, and either spherical or deflated in shape. Aerodynamic mass mean diameter was 2.7 μm. Nanocrystalline TiO2 was obtained after thermal post-annealing for one hour. An expected tendency to convert to anatase crystalline phase up to 500°C and subsequently to rutile phase up to 900°C in the annealing was observed. The results show that the in-droplet hydrolysis is a viable method in preparing fine Ti–O powder particles with controlled properties.