Characterization of oxygen-dependent stability of selected mixed-conducting perovskite oxides

By coulometric titration experiments performed on selected state-of-the-art MIEC powder samples in a tubular zirconia “oxygen pump” setup, facilitating precise control of the oxygen partial pressure in the entire range between pO2 = 10− 18…1 bar at temperatures between 700…1000 °C, the low-pO2 stability limits can be determined. By monitoring the electrical current necessary for pumping oxygen through the solid electrolyte into or out of the measurement chamber, the amount of oxygen transported and, thus, changes in oxygen stoichiometry can be determined. The low-pO2 stability limits for all investigated high-performance MIEC oxides were similar (below 10− 10 bar at 900 °C).