IMMITTANCE RESPONSE OF LA0.6SR0.4CO0.2FE0.8O3 BASED ELECTROCHEMICAL-CELLS

The ac small-signal response of La0.6Sr0.6Co0.2Fe0.8O3 (LSCF) is examined via lumped parameter/complex plane analysis (LP/CFA) technique. The ac data, acquired in the frequency range 10(-1) less than or equal to f less than or equal to 10(6) Hz, are used to establish the role of ionic contribution in the LSCF material system using a two-terminal blocking electrode method. Spun-on yttria (8 mole percent (m/o) Y2O3) stabilized zirconia (8YSZ) or Ce0.85Sm0.15O2 (CSO) thin film coatings (0.3 - 1.0 mu m) is used as electron blocking electrodes. The temperature dependence of the contributing elements between the terminals, obtained via LP/CPA technique and de measurements, is evaluated. The activation energy, associated with possible oxygen transport via an anion vacancy mechanism, is found to be similar to 1.1 eV in the temperature range of 400-800 degrees C. The effect of thickness and composition of the blocking electrodes are discussed. Finally, the advantages of the thin-film blocking electrodes compared to mechanical contact blocking electrodes are also presented.