Titania Aggregates Formed by Hydrolysis of Ti(OH)4-HCl-H2O Concentrated Solutions
Keiji DAIMON, Kouki HORIBA, Yang GUANG, Yasuo HIKICHI and Toshitaka OTA
Abstract:Concentrated Ti(OH)4-HCl-H2O solutions were prepared from TiCl4 and adjusted to the composition of Cl|^Ti‚S{=3 in molar ratio. The crystalline phases and particle morphologies were investigated concerning with the hydrolysis conditions. The titania (TiO2) powders with fine particles were formed from the solution with the concentration ranging from 0.5 mol/l to 4.0 mol/l. The anatase crystallizes, at first, and then anatase ¨ rutile phase transition takes place. The rate of the phase transition increases with increasing the concentration of the solution. These products were composed of very fine primary particles having large specific surface areas of about 250 m2/g for anatase and 87 m2/g for rutile, respectively. Aggregates with the size ranging from 0.1 to 0.8 ƒÊm were formed from the 3.0 mol/l solution at 96 Ž for 24 h. The aggregates become larger as decreasing the concentration of the solution. Spherical aggregates of about 3ƒÊm in size was formed from 3 mol/l solution. Key Words:Titania, Hydrolysis, Concentrated solution, Aggregated nano-particles