Electrical and electrochemical behaviour of LaCoO3-δ+La2(ZrY)2O7-based electrode materials

LaCoO3-delta/La-2(Zr;Y)(2)O-7-based composites were designed with thermal expansion coefficients below 15 X 10(-6)degrees C-1 and dc conductivities higher than 100 S cm(-1) at 800 degrees C. Resistance to thermal cycling was evaluated by the deterioration of electrical properties and was found to be satisfactory. Percolation of the highly conducting phase is retained for fractions of LaCoO3-delta as low as about 30% in volume. Thin films were screen-printed on gadolinia-doped ceria (GCO) substrates for electrochemical characterisation. Electrode thickness and porosity were varied by changing the concentration of solids and the sintering temperature. Results suggest some dependence on cathodic polarisation on the electrode surface area in contact with the gas atmosphere. The best composite electrode has shown better electrode performance than LaMnO3-based materials and also has a good resistance to thermal cycling. (C) 1999 Elsevier Science B.V. All rights reserved.