Surface and interface characteristics of TiO2–muscovite nanocomposites

The morphology and chemical characteristics of the surface and the interface of TiO2–muscovite nanocomposites were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Our results clearly showed that TiO2 grains formed on the TiO2 thin film surface, whereas the presence of TiO2 grains on the interface between TiO2 thin films and the muscovite substrates was not obvious. While euhedral rutile grains were found in samples doped with Zn ions, none were found in samples doped with Sn ions. The XPS results showed that cations present in the muscovite substrates diffused into the TiO2 thin films. Etching measurements revealed that diffusion abilities of cation impurities varied: Si and Al diffused more easily than K. The observed differences in chemical composition and oxidation of the elements, especially on the surface and the subsurface, may influence the different crystallization behaviors of elements in TiO2 thin films and the different active degree of elements diffusing from muscovite substrates.