Variable temperature in situ X-ray diffraction study of mechanically activated synthesis of calcium titanate, CaTiO 3

Abstract

The effect of mechanical activation on formation of calcium titanate (CaTiO 3) from calcined mixtures of CaCO 3 and TiO 2 was studied by monitoring the course of this solid-state reaction by variable temperature in situ X-ray diffraction (XRD) experiments, scanning electron microscopy (SEM) and dilatometry. Two equimolar mixtures of powdered CaCO 3 and TiO 2 were prepared: one was mechanically activated by grinding in a high energy vibro-mill. A total of 32 X-ray diffraction data sets for each sample, collected between 30 and 1100 °C, were analyzed by multiphase Rietveld refinement. Quantitative phase analysis and microstructure analysis obtained from X-ray diffraction are correlated to results of scanning electron microscopy and dilatometry. In the non-activated sample, small quantities of the reactants remain in the product until 1100 °C. In the activated sample, the reaction results in pure CaTiO 3 at 920 °C.