Phase Transformation of TiO₂ in the Preparation of Pearlescent Pigment

The TiO2/mica pearlescent pigments were prepared by the hydrolysis of TiOCl2 on the natural mica (muscovite) followed by a calcinations process. The phase transformation of anatase to rutile during calcination and their proportion in the TiO2 thin layer have been analyzed by XRD measurements. The pH controlling during the initial stage of hydrolysis of TiOCl2 showed a pronounced effect on the phase transformation of TiO2 on the substrate. This result may be due to the fact that the pH controlling during the hydrolysis affects the crystal structure and size of TiO2. The decrease in crystallinity and crystallite size of TiO2 resulted in lowering the temperature of phase transformation from anatase to rutile.