Influence of the autocombustion synthesis conditions and the calcination temperature on the microstructure and electrochemical properties of BaCe0.8Zr0.1Y0.1O3-δ electrolyte material

This study focuses on the influence of the microstructure on the conductivity of the BaCe0.8Zr0.1Y0.1O3-delta compound, prepared by nitrate-glycine autocombustion, with a special attention to the influence of less studied parameters, i.e. the nature of the precursors and the ratio between the nitrate precursors and the glycine, and the temperature of the calcination step. It has been shown that the nature of the precursors and the ratio between the nitrate precursors and the glycine impact strongly both the microstructure of the powders after autocombustion and of the pellets calcined at 1000 degrees C and sintered at 1400 degrees C. The highest total conductivity in dry air (above 10(-2)S/cm from 700 degrees C) was obtained for a sample without secondary phase. The impact of the calcination temperature was subsequently studied between 700 degrees C and 1000 degrees C on this latter sample. EIS measurements make possible the differentiation of the grain and grain boundary contributions to the total conductivity, in accordance with the change of the microstructure visible on SEM images after sintering of pellets calcined at different temperatures. It has been shown that the grain boundaries play a key role on the evolution of the total conductivity of BaCe0.8Zr0.1Y0.1O3-delta, which is, at high temperatures, mainly anionic.