Reaction mechanism in solid BaCe0.9Y0.1O3 – liquid BaWO4 system

Abstract

BaCeO3–based protonic conductors may be considered as perspective materials for construction of various electrochemical devices as fuel cells, gas sensors, electrochemical pumps, separators or membrane chemical reactors. The desired properties, as high electrical conductivity or chemical stability of these materials may be further improved by formation of composite, by introduction of modifying phase as BaWO4 into the host Y-doped BaCeO3 material. The high temperature process of composite formation requires the recognition of chemical reactivity between the used component. In this work the mutual reactivity and reaction mechanism in the solid BaCe0.9Y0.1O3 – liquid BaWO4 system were investigated. The synthesis of BaCe0.9Y0.1O3 and BaWO4 compounds was done by solid-state reaction method. The formation of BaCe0.9Y0.1O3 – BaWO4 materials was obtained by high temperature impregnation of melted BaWO4 into solid BaCe0.9Y0.1O3 with different impregnation time applied (2, 4 and 8 h). The evolution of crystal structure, phase composition, microstructure, chemical composition and electrical properties with impregnation time, for surface and interior of the samples allowed to analyse the mutual reactivity of composite components and to propose the multi-step reaction mechanism in the solid BaCe0.9Y0.1O3 – liquid BaWO4 system.