Physico-chemical and microbiological Effect of sputtered photocatalytic Titanium Oxide Layers

Crystalline TiO2 layers show interesting properties for different applications. Rutile layers can be used as optical layers with high refractive index and as transparent protective layers with good mechanical properties. Both, anatase and rutile are photo-semiconductors and exhibit in a different degree photocatalytic, photo-induced hydrophilic and antifogging properties. For a better control of the TiO2 deposition and thin film properties a special deposition system has been developed: a reactive pulse magnetron sputtering (PMS) system. Layers with different content of crystalline phases were deposited at dynamic deposition rates of about 45 nm . m/min (corresponding to about 160 nm/min in a stationary coating system). Moreover, the anionic doping of the layers succeeded by nitrogen as well as the cationic doping by different metals. The layer structure was determined by XRD. Furthermore, the following properties connected with photo-induced hydrophilicity or photocatalysis were studied: the photo-induced decrease of the water contact angle, the decomposition of methylene blue and lumogen orange as well as the inhibition of algae and bacteria. By doping the layers some of these properties can be improved significantly in comparison to undoped titanium oxide. Some doped layers showed a high activity also under visible irradiation only without UV.