Kinetics of the anatase rutile transformation in TiO2 in the presence of Fe2O3

The anatase rutile phase transition in TiO2 in the presence of Fe2O3 was investigated in air and argon atmospheres by means of X-ray diffraction and scanning electron microscopy. Isothermal curves of rutile transformed from anatase as a function of time were obtained between 825 and 950 degrees C. The data were well fitted by various rate laws. In the presence of Fe3+, the anatase rutile transition temperature is lower and the transformation rate in air is higher than the corresponding one in pure TiO2. The transformation in the presence of Fe3+ in an argon atmosphere is more rapid than in air. The enhancement effect of Fe3+ on the anatase rutile transformation in both atmospheres is understood on the basis of the formaiton of oxygen vacanies. (C) 1998 Chapman & Hall.