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

The ac small-signal response of La0.6Sr0.6Co0.2Fe0.8O3 (LSCF) is exami ned via lumped parameter/complex plane analysis (LP/CFA) technique. Th e ac data, acquired in the frequency range 10(-1) less than or equal t o 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 bl ocking electrode method. Spun-on yttria (8 mole percent (m/o) Y2O3) st abilized zirconia (8YSZ) or Ce0.85Sm0.15O2 (CSO) thin film coatings (0 .3 - 1.0 mu m) is used as electron blocking electrodes. The temperatur e dependence of the contributing elements between the terminals, obtai ned via LP/CPA technique and de measurements, is evaluated. The activa tion energy, associated with possible oxygen transport via an anion va cancy mechanism, is found to be similar to 1.1 eV in the temperature r ange 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.