Rutile growth at the surface of TiO2 films deposited by vapour-phase decomposition of isopropyl titanate

Isopropyl titanate has been decomposed in the vapour phase to give an anatase film on glass substrate under conditions of slow deposition. It was found that rutile grew on the film surface as the films become thicker than ca. 10 µm and when film growth was rapid at substrate temperatures between 450 and 500 °C. In an extreme case the film surface became pure rutile on top of anatase crystals. The occurrence of this phenomenon is explained by the rapid epitaxial growth of dendritic rutile crystals on the rutile crystallites, which protrude over the columnar anatase crystals and suppress their growth. A similar mechanism can be assigned to TiO2 deposition from the other alkyl titanates, especially ethyl titanate, which generates more rutile nuclei than isopropyl titanate in vapour-phase decomposition and so can provide rutile films as thin as 0.5 µm.