Sr1-xBaxSnO3 system applied in the photocatalytic discoloration of an azo-dye

International audienceSemiconductor materials have received substantial attention as photocatalysts for controlling water pollution. Among these materials, perovskite-structured SrSnO3 is a promising candidate for this application, whereas BaSnO3 exhibits very low activity. In the present work, Sr1−xBaxSnO3 (x = 0, 0.25, 0.50, 0.75 and 1) was synthesized by solid-state reaction and was applied in the photocatalytic discoloration of the organic dye Remazol Golden Yellow. The perovskite structure was obtained for all compositions of the solid solutions with both Sr2+ and Ba2+ present in the lattice. A remarkable change in the short-range symmetry was observed as the amount of Ba2+ increased, and this change led to a decrease in the band gap of the material. Although the BaSnO3 was not active toward water photolysis, the discoloration induced by this perovskite was twice that induced by SrSnO3. The two materials appear to feature different mechanisms of photodegradation: the direct mechanism prevails in the case of BaSnO3, whereas the indirect mechanism appears to play a key role in the case of SrSnO3

KTaO3 powders and thin films prepared by polymeric precursor method

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Evolution of the structural and microstructural characteristics of SrSn_{1 - x}Ti_xO₃ thin films under the influence of the composition, the substrate and the deposition method

International audienceSrSn1 - xTixO3 thin films were grown on R-sapphire and (100) LaAlO3 single crystal substrates by two different routes: chem. soln. deposition (CSD) and pulsed laser deposition (PLD). Structural and microstructural characteristics of the films were detd. by X-ray diffraction (θ-2θ, ω- and φ-scans) and field emission SEM. Pure perovskite phase was obtained for all of the compns., whatever the method of deposition and the substrate nature. On R-sapphire, a randomly oriented growth (polycryst.) was obsd. for all of the compns. deposited by CSD while (h00) preferential orientation was attained when deposition was done by PLD, in particular for SrTiO3 compn. The phi-scan performed on this sample revealed that the (100) oriented grains present an in-plane ordering (epitaxial growth) with respect to the substrate with an alignment of the [011] direction of the film along the [121[n.773]] direction of the substrate, explained on the basis of misfit considerations and interface arrangements. All of the films grown on (100) LaAlO3 exhibited an epitaxial growth with an in-plane relationship 〈010〉film // 〈010〉substrate. As for the thin film microstructure, porosity, homogeneity, shape and size of the grains were strongly influenced by Ti content in the SrSn1 - xTixO3 solid soln., and also by the nature of the substrate and by the deposition method. Moreover, the influence of the compn. and thin film growth on the photoluminescence of SST films were also evaluated