DOPANTS IN FLAME SYNTHESIS OF TITANIA

The effect of dopants on the characteristics of titania particles made by oxidation of TiCl4 in a laminar diffusion flame reactor is presented. Introduction of dopant SiCl4 inhibits the transformation of anatase to rutile, due to the formation of interstitial solid solution of SiO2 and TiO2. Silica decreases the sintering rate of titania and decreases the primary particle size, and, as a result, the specific surface area increases. Introduction of SnCl4 enhances the transformation of anatase to rutile, due to the similar crystalline structure of SnO2 and rutile titania. However, the presence of SnO2 does not affect the primary particle size or the specific surface area of titania particles, Introduction of AlCl3 enhances the transformation of anatase to rutile, due to the formation of excess oxygen vacancies as Al2O3 and TiO2 form a substitutional solid solution,