Crystal structure transformation of TiO2 in presence of Fe2O3 and NiO in air atmosphere

TiO2 is produced and marketed in two main grades viz. anatase and rutile. Both anatase and rutile have their own pigmentry properties and hence cannot be substituted by each other. Pure anatase on heating at higher temperatures undergoes crystallographic rearrangement to form rutile. This transformation in presence of NiO and Fe2O3 under air atmosphere was studied using XRD and SEM. The transformation temperature was found to be reduced much in presence of NiO and Fe2O3 and the extent of lowering was higher for NiO than Fe2O3. The activation energy for this transformation was also calculated. The method of preparation had major influence on the transformation.