IONIC AND ELECTRONIC CONDUCTIVITIES OF LACOO3-BASED AND LAMNO3-BASED PEROVSKITE-TYPE OXIDES MEASURED BY THE AC-IMPEDANCE METHOD WITH ELECTRON-BLOCKING ELECTRODES

The ionic conductivities, sigma(i), of La0.6Sr0.4Co1-yNiyO3 (y=0, 0.02) have been measured by the a.c. four-probe method with electron-blocking electrodes, and compared with diffusivity of oxygen from the oxygen isotopic-exchange reaction. The ionic conductivities estimated from both methods are similar. Sigma(i) values for the perovskite-type oxides La0.6Sr0.4Co0.98Ni0.02O3 were higher than that of (ZrO2)0.92 (Y2O3)0.08 (YSZ), and the ionic transference numbers were in the range 1 x 10(-4)-5 x 10(-6) for 900-600-degrees-C. La0.6Sr0.4MnO3 is considered to exhibit lower ionic conductivities than La0.6Sr0.4Co1-yNiyO3 (y=0, 0.02) and sigma(i), of this oxide could not be measured by the a.c. four-probe method with electron-blocking electrodes.