Browsing by Author "Rey A."

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    In-situ sol-gel synthesis and thin film deposition of Cu(In, Ga)(S, Se)2 solar cells
    (2013-12-17) Oliveira L.; Lyubenova T.; Martí R.; Fraga D.; Rey A.; Kozhukharov V.; Carda J.
    Chalcogenide-based solar cells Cu(In, Ga)(S, Se)2 were developed using an in-situ sol-gel method and spin coating thin film deposition. The influence of chemical composition and thermal treatment were studied in detail. It was revealed that these variables are related to band gap changes and final device performance. Increasing in band gap experimental values (1.18-1.67 eV) was observed, due to the formation of solid solution of Ga (III) and S (-II) incorporation in the crystal lattice. Optimal device performance of 3,1 % efficiency of solar energy conversion was achieved for the Cu(In1-xGax)(S, Se)2 solid solution.
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    Rheological effect of different deflocculation mechanisms on a porcelain ceramic composition
    (2015-01-01) Barrachina E.; Llop J.; Notari M.; Fraga D.; Martí R.; Calvet I.; Rey A.; Lyubenova T.; Kozhukharov S.; Kozhukharov V.; Carda J.
    The current environmental policy imposes general optimisation of the industrial process. There are two critical steps related to suspensions fluidity in the ceramic spray-drying industry: the emptying of the ball mill and the spray-drying operation. The chemicals producers provide a large number of commercial deflocculants aiming to improve both processes. The present research is focused on the comparison of the rheological effect of four commercial liquid deflocculants on a porcelain ceramic composition in view of different mechanisms of deflocculation. The suspensions prepared have 70 %-solid content and a range of deflocculant concentrations between 0.1 mass % and 0.6 mass %. Each suspension is characterized by measuring its solid content, particle size distribution, pH values, conductivity and rheology, including viscosity at two shear rates and thixotropy calculated from the hysteresis area of the flowability curves. On the basis of the experiments carried out adequate conclusions are presented.