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2006
Conference Paper
Titel
TiO2 as a photocatalytic material: Properties, film deposition, technical applications
Alternative
TiO2 als Photokatalysator - Eigenschaften, Herstellung, Industrialisierung
Abstract
There are numerous technical applications of TiO2: it is used in paints, in printing inks, in paper and fibres, in thermoplastics, and in thin film optics, to name a few. Nowadays, TiO2 is also used as a photocatalytic material. A photocatalyst is a substance that is able to produce, by absorption of light quanta, chemical transformations of the reaction participants, repeatedly coming with them into the intermediate chemical interactions and regenerating its chemical composition after each cycle of such interactions. As an example, the generation of oxygen radicals at a TiO2 surface may be used to oxidize organic materials and thus mineralize hydrocarbons or to kill bacteria and fungi. Thin TiO2 films can be deposited by spray pyrolysis, conventional DC/RF sputtering, or PECVD. In order to obtain crystalline TiO2 phases at relatively low temperatures, the growing film can be agitated by plasma born particle bombardment. In this article, TiO2 deposition using plasma activation indifferent high rate PVD techniques is described. It is concluded that plasma impact influenced films show higher hardness, higher refractive index and higher photocatalytic performance. Crystalline TiO2 films can be obtained at temperatures < 250 deg C, significantly lower than the annealing temperatures (> 350 deg C - 650 deg C) required to form anatase or rutile. These crystalline layers exhibit better photocatalytic properties than post-annealed amorphous layers.