Study on Crystalline Phase Transformation of Nano-sized TiO_2 in the Low Temperature by using SnCl_4

In this paper, two control methods of crystalline phase transformation of nano sized TiO2 in the low temperature were presented. The first method is sol gel process using ethanol as solvent and tetrabutyl titanate as reactant. By controlling the quantity of addition of SnCl4, the crystalline structure of TiO2 can be controlled from pure anatase, to the composite phases(rutile and anatase), and to pure rutile at temperature of 450℃. The second method is directly hydrolysis of tetrabutyl titanate at low temperature without adding any solvent. By controlling the quantity of addition of SnCl4, the crystalline sols of TiO2 with the average particle diameter of 3～8nm are prepared. The crystalline structure of TiO2 sols can be transformed from pure anatase, to the composite phases(anatase, brookite and rutile), and to pure rutile by drying at 120℃, the nano sized TiO2 powders with required crystalline phase can be obtained. All the samples were characterized by TEM and XRD. The results showed that nano sized TiO2 and TiO2 SnO2 had small particle size, uniform distribution and high dispersion. But X ray characteristic peaks of tin dioxide crystal were not detected.