Effect of HCl concentration and reaction time on the change in the crystalline state of TiO2 prepared from aqueous TiCl4 solution by precipitation

TiO2 powder with 50% by volume or more of brookite phase was obtained by heating aqueous TiCl4 solution, whose final concentration of HCl after reaction was kept between 4.9 and 6.4 M, at 80 degrees C for 15 h. Rutile-type TiO2 was obtained at 5 h of reaction time, a mixture of predominant brookite and rutile at 10-15 It while rutile phase was formed at 25 h. Brookite phase was transformed directly to rutile phase with increase of reaction time but to rutile via anatase phase through heat treatment. (c) 2004 Elsevier Ltd. All rights reserved.