Electrode behaviour at (La,Sr)MnO3/Y2O3–ZrO2 interface by electrochemical impedance spectroscopy

The electrode behaviour of strontium (Sr)-doped LaMnO3 (LSM) electrodes is investigated by an electrochemical impedance spectroscopy technique over the temperature range 850–1000 °C and the oxygen partial pressure range 0.01–0.21 atm. The electrodes are screen-printed on 50 mm×50 mm 3 mol% Y2O3–ZrO2 electrolyte cells with an electrode surface area of 10 cm2. The impedance responses show two separable arcs and are analysed in terms of two different equivalent circuits with comparable information on the electrode processes at high and low frequencies. The electrode process associated with the high-frequency arc is essentially independent of O2 partial pressure with an activation energy of not, vert, similar74 kJ mol−1, while that at the low-frequency arc has an activation energy of not, vert, similar202 kJ mol−1 and a reaction order with respect to O2 partial pressure of not, vert, similar0.5 at low temperatures and not, vert, similar0.85 at high temperatures. The electrode processes associated with the low- and high-frequency arcs are discussed.