Preparation and film-growing mechanism of hydrous zirconia coated on TiO2

To overcome the photochemical activity of rutile used as a pigment and improve its durability in application, hydrous zirconia-coated TiO₂ was prepared by the precipitation method. High-resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and surface structure of hydrous zirconia-coated TiO₂. The ζ-potential and ultraviolet (UV) absorption of both coated and uncoated rutile were examined. The results show that hydrous zirconia can not only improve the durability but also raise the lightness. A suitable ZrO₂ content of hydrous zirconia-coated TiO₂ is about 1.0wt%, and a dense film on the surface of rutile can be formed with better pigmentary properties. Based on the thermodynamic analysis, the zirconia-coating process and the film growth mechanism were discussed.