Oxygen exchange, thermochemical expansion and cathodic behavior of perovskite-like Sr0.7Ce0.3MnO3-δ

The oxygen tracer diffusion and surface exchange coefficients of Sr0.7Ce0.3MnO3-δ (SCM), measured by the 18O/16O isotopic exchange depth profile method with time-of-flight secondary-ion mass spectrometric analysis at 973-1123 K, are substantially higher than those of (La,Sr)MnO3-δ. Testing of model solid oxide fuel cells (SOFCs) with SCM cathodes, ceria-based protective interlayers and Ni-containing cermet anodes demonstrated a relatively good and stable performance. For 0.5 mm thick solid electrolyte membranes made of ZrO2- 10 mol% Sc2O3- 1 mol% Y2O3 and doped lanthanum gallate, the maximum power density at 1073 K was approximately 170 and 230 mW/cm2, respectively, without microstructural optimization and surface modification of the electrodes. Compared to another promising family of SOFC cathode materials, (La,Sr)(Co,Fe)O3-δ, SCM exhibits significantly lower thermal and chemical expansion assessed by the controlled-atmosphere dilatometry.