Prepapration and Phase Thansformation Kinetics of Ultrafine Titania

Nanocrystalline titania powder was obtained from titanium tetrachloride by chemical method.After hydrolysis of titanium tetrachloride, one sample was neutralized by NH3.H2O at once, and the other was neutralized one day later. The former was detected to be sphericed anatase titania,whereas the latter a mixture of anatase and rutile titania. Both samples have the average diameters of 15nm, ranging from 10 to 20nm. Phase transformation from anatase to rutile occurs at 923K,and its activation enthalpy is 113.5±8.97kJ/mol.