Electrical and electrochemical behaviour of LaCoO3-delta+La-2(ZrY)(2)O-7-based electrode materials

LaCoO3-delta/La-2(Zr;Y)(2)O-7-based composites were designed with thermal e xpansion coefficients below 15 X 10(-6)degrees C-1 and dc conductivities hi gher 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 f ractions of LaCoO3-delta as low as about 30% in volume. Thin films were scr een-printed on gadolinia-doped ceria (GCO) substrates for electrochemical c haracterisation. Electrode thickness and porosity were varied by changing t he concentration of solids and the sintering temperature. Results suggest s ome dependence on cathodic polarisation on the electrode surface area in co ntact with the gas atmosphere. The best composite electrode has shown bette r electrode performance than LaMnO3-based materials and also has a good res istance to thermal cycling. (C) 1999 Elsevier Science B.V. All rights reser ved.