THE EFFECT OF CALCINATION ON THE SURFACE-COMPOSITION AND STRUCTURE OF TITANIUM-DIOXIDE COATED MICA PARTICLES

Thin layers of polycrystalline TiO2 were deposited on flaky muscovite and phlogopite particles. Deposition was performed in a water slurry using aqueous TiCl4 as the titanium source. The effects of heat treatments on the surface composition of thin TiO2 films were studied by XPS technique. The surface composition was strongly dependent on the calcination temperature. The substrate components diffused through the film and as a consequence the outermost surface was a mixture of oxides of titanium, silicon, aluminum, and sodium. Surface composition was not affected by calcination after a certain induction period. The diffusing cations are believed to have an effect on the anatase-to-rutile transformation which was observed in the TiO2-phlogopite system but not in the TiO2-muscovite system. © 1993 Academic Press, Inc.