Effect of compressive stress inducing a band gap narrowing on the photoinduced activities of sol-gel TiO films

M.N. Ghazzal, N. Chaoui, M. Genet, E.M. Gaigneaux, D. Robert

    Research output: Contribution to journalArticlepeer-review

    Abstract

    TiO thin films grown on different kinds of substrates were obtained by sol-gel process. X-ray diffraction revealed that the TiO lattice parameter c decreased continuously, indicating a continuous variation in the compressive stress, a negligible compressive stress of the film grown onto Soda-Lime Glass (SLG), medium compressive stress of the film grown onto BoroSilicate Glass (BSG) and large compressive stress of the film deposited onto the Quartz Substrate (QS). UV-Vis absorbance spectra exhibited a red-shift of the absorbance edge of the TiO films suggesting a lowering of the band gap, which is a direct consequence of the increase of the compressive stress. X-ray photoelectron spectroscopy revealed that the surface composition of titania films was similar except for sodium-ion concentration. The rate observed during the photo-oxydation of the stearic acid on TiO /QS was twice as high as that of TiO /BSG and about 1000 times superior to that of TiO /SLG. The photoinduced wettability shows an identical dependence of the compressive stress. According to these results, the compressive stress could be used to tune the band gap of the titanium oxide in order to enhance the photoinduced properties.
    Original languageEnglish
    Pages (from-to)1147-1154
    Number of pages8
    JournalThin Solid Films
    Volume520
    Issue number3
    DOIs
    Publication statusPublished - 30 Nov 2011

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