Crystallization kinetics and phase relations of wollastonite by real time synchrotron powder diffraction

The crystallization kinetics of 1T-wollastonite in the CaO-SiO2 system starting from a stoichiometric glass has been investigated in situ by X-ray synchrotron powder diffraction in the temperature range 800-900 °C. At higher temperature, 1T-wollastonite converts into the 2M polytype. The collected data were analyzed by the Avrami models and kinetic parameters seem to indicate a nucleation deceleratory controlled mechanism with one-dimensional growth. The preliminary results of this study are part of a general project aimed to investigate polymorphism and polytypism of wollastonite and the related phases, especially the role of the kinetic parameters in the formation of the polytypes in the pyroxenoid series.