Thermodynamic analysis of nucleation of anatase and rutile from TiO2 melt

We analyzed the nucleation of rutile and anatase from titanium dioxide (TiO2) melt by a thermodynamic calculation using estimated values of the interfacial energy between the condensed phases and the liquid phase in the pure TiO2 system. The results show that the as-solidified phase depends on the solidification temperature or degree of supercooling of the TiO2 melt. Under a high cooling rate, anatase nucleates directly from the melt below 2057K, while stable rutile solidifies at a temperature close to the melting point of TiO2. This result agrees with the experimental observation that anatase is formed in a rapid cooling process, while rutile is formed under near-equilibrium solidification conditions. (C) 2002 Elsevier Science B.V. All rights reserved.