Effects of aging on nanocrystalline anatase-to-rutile phase transformation kinetics

The effects of aging on the kinetics for nanocrystalline anatase-to-rutile phase transformation were investigated. The agglomeration and crystallite sizes for TiO2 gels decreased with increasing aging treatment. For unaged samples, the agglomeration number was high, so that there are a larger number of anatase crystallites and crystallite-crystallite anatase contacts in each cluster. This promotes interfacial nucleation. Therefore, the activation energy of nucleation calculated for unaged samples was smaller than that for those found for the aged ones. (C) 2007 Elsevier Ltd and Techna Group S.r.l. All rights reserved.