Reactivity of solid BaCe0.9Y0.1O3-δ towards melted WO3

Abstract

High-temperature impregnation of solid single-phase Y-doped BaCeO3 with melted WO3 was performed towards the evaluation of the possibility of formation of chemically stable material with relatively high electrical conductivity in this system. Impregnation was performed at 1470 °C as a function of time. Due to the relatively high reactivity in solid BaCe0.9Y0.1O3-δ - liquid WO3 system the reactive and the inner layers were distinguished and analysed. The obtained results clearly indicate the decomposition of Y-doped BaCeO3 in contact with melted WO3. X-ray diffraction method together with SEM observation, EDS analysis and EIS measurements results were applied to discuss the mechanism of this multi-stage process and the influence of the reaction time on materials structure and microstructure. As it was observed, partial incorporation of tungsten into the barium cerate structure can process not only on the surface of the materials but also in the inner layer of the synthesised materials. This donor-type doping of the perovskite structure finds reflection in both, materials electrical properties and chemical stability towards CO2/H2O. The decrease of proton defects concentration was observed together with the significant increase of the materials chemical stability in comparison to un-modified single-phase BaCe0.9Y0.1O3-δ. The calculated values of activation energy of conductivity confirm the change in the conduction mechanism. Also, the presence of an additional phase in the intergranular voids of doped BaCeO3 was postulated.