Abstract

A compact TiO₂ film with a thickness of about 90 nm has been coated onto stainless steel substrates by using the sol–gel method with Ti(OBu)₄ as precursor. AES analysis showed that Fe diffused from the substrate into the TiO₂ film and reacted with O₂ from the air, resulting in the formation of an interlayer of iron oxide during the annealing process. XPS and XRD results indicate that the Fe in the TiO₂ layer and interlayer exists as a rhombohedral Fe₂O₃ species. With increasing annealing temperature and time, the diffusion can be significantly promoted. Although iron oxide did not react with TiO₂ film, the formation of anatase TiO₂ film was impeded due to the presence of Fe. It has been proven by UV spectroscopic analysis of TiO₂ film that Fe enters the TiO₂ lattice and changes the lattice parameters, resulting in a change in the optical properties of the TiO₂ film photocatalyst.