Stability of Ba(Zr,Pr,Y)O3−δ materials for potential application in electrochemical devices

Ba(Pr1−xZrx)1−yYyO3−δ materials were obtained by a two-step process of mechanical activation followed by annealing at 1250 °C. Guidelines for correlations between structure and composition, and their role on stability were characterised as a function of atmosphere, with special emphasis on degradation by carbonation in CO2-rich atmospheres, or upon redox changes. The role of humidity on these degradation processes was also analysed by taking into account differences between wet and dry atmospheres with regards to the onset of secondary phases and structural changes. Thermodynamic calculations were used to predict 2-phase and 3-phase equilibria in contact with CO2-rich atmospheres and to obtain corresponding stability diagrams. The thermodynamic calculations were also used as guidelines for the progress of carbonation in isothermal conditions, and also with variable temperature, namely on cooling carbonate free materials from high temperatures, or on re-heating under CO2.