Underscoring the transport properties of yttrium-doped barium cerate in nominally dry oxidising conditions

The current work assesses the transport properties of BaCe0·9Y0·1O3-d (BCY10) in oxidising atmospheres as a function of water vapour partial pressure (pH2O = ∼10−7 – 0.1 atm) in the intermediate temperature range 350–600 °C. From these data and those measured under similar conditions in H2, from literature data, the transport numbers of this material in both reducing and oxidising conditions are compared. Contrary to that observed in reducing atmospheres, where feeding with nominally dry hydrogen-based atmospheres was sufficient to provide high levels of protonic conductivity, in oxidising conditions the material can only exhibit significant protonic conductivity by externally imposing more elevated pH2O values (10−5 – 10−4 atm). From this knowledge, the current article provides the first detailed clarification of the limiting conditions of operation of BCY10 under low humidity values and, subsequently, highlights the relevance of this finding to cell efficiency and membrane stability in the intermediate temperature range.