Abstract
The segregation of constituent elements and impurities affects the surface composition of solid oxide electrode materials, and hence, the rate of the surface exchange reaction. In this work, we compare segregation occurring at 400 °C in Pr0.5Sr0.5CoO3-δ (PSCO) and PrBaCo2O5-δ (PBCO). The surface composition changes rapidly on annealing at low temperature, with segregation of the divalent cation evident after just 15 minutes. The PBCO contained a Na impurity which undergoes similar segregation behavior to the Ba, becoming the dominant surface cation after 2 hours of annealing. Although cation mobility in these materials is slow compared to oxygen, it is sufficient to cause significant changes in surface composition on timescales of the order of hours.
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