Ionic and electronic conductivities of LaCoO3- and LaMnO3-based perovskite-type oxides measured by the a.c. impedance method with electron-blocking electrodes

Abstract

The ionic conductivities, σ_i, of La_0.6Sr_0.4Co_1–yNi_yO₃(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. σ_i; values for the perovskite-type oxides La_0.6Sr_0.4Co_0.98Ni_0.02O₃ were higher than that of (ZrO₂)_0.92(Y₂O₃)_0.08(YSZ), and the ionic transference numbers were in the range 1 × 10^–4– 5 × 10^–6 for 900–600 °C. La_0.6Sr_0.4MnO₃ is considered to exhibit lower ionic conductivities than La_0.6Sr_0.4Co_1–yNi_yO₃(y= 0, 0.02) and σ_i of this oxide could not be measured by the a.c. fourprobe method with electron-blocking electrodes.