Use of ion-assisted sputtering technique for producing photocatalytic titanium dioxide thin films: Influence of thermal treatments on structural and activity properties based on the decomposition of stearic acid

Publication date: Available online 21 September 2018Source: Polymer Degradation and StabilityAuthor(s): V. Vishnyakov, P.J. Kelly, J. Humblot, R.J. Kriek, N.S. Allen, N. MahdjoubAbstractTitanium dioxide thin films were deposited by the reactive ion-assisted sputtering method from titanium targets at various partial pressures and deposition parameters. The films were deposited onto substrates at temperatures ranging from room-temperature conditions to 722 K. A selection of thin films was post-deposited annealed at temperatures up to 972 K for 10 min and characterized by micro-Raman spectroscopy and scanning electron microscopy (SEM) and subsequently analysed to assess their photocatalytic activity. Micro-Raman characterization revealed that the as-deposited films had either predominant amorphous, rutile-like structures, anatase-like structures or anatase-rutile mixed structures. The thin films deposited with a high substrate temperature and with energy assistance from the ion source tended to be amorphous, while films deposited on a hot substrate without ion energy assistance tended to have a mixed crystalline phase. On subsequent annealing the amorphous films changed to a rutile structure at temperatures above 672 K, while mixed anatase-rutile films changed to predominant rutile structures only after thermal treatments above 872 K. Thus, this study has revealed an astonishing persistence of the anatase-rutile mixed phase at very high temperatures and showed the poss...

Source: Polymer Degradation and Stability - September 22, 2018 Category: Chemistry Source Type: research