Electrochemical Characterization of a La0.8Sr0.2Ni0.4Fe0.6O3-δ Electrode Interfaced with La9.83Si5Al0.75Fe0.25O26{plus minus}δ Apatite-type Electrolyte

Abstract

The electrochemical characteristics of a La0.8Sr0.2Ni0.4Fe0.6O3 cathode electrode interfaced to La9.83Si5Al0.75Fe0.25O26{plus minus}δ apatite-type electrolyte were studied using AC impedance spectroscopy under open circuit conditions, at temperatures 600 to 800 oC and oxygen partial pressures in the range 0.1 to 20 kPa. The cathode and electrolyte powders were prepared via the Pechini method and the mechanochemical activation method, respectively. The electrocatalytic activity of the tested interface was assessed on the basis of its open circuit area specific polarization conductance , determined from the impedance data. The polarization conductance was found to increase with increasing , following power law dependence. The impedance characteristics of the system were determined by at least two different processes, corresponding to two partially overlapping depressed arcs in the Nyquist plots. The relative contribution and degree of overlap of these arcs depended on temperature and oxygen partial pressure.