Preparation and Electrochemical Characterization of Perovskite/YSZ Ceramic Films

Abstract

Perovskite-type powders were prepared using a complex polymeric precursor method. Thermal analysis was carried out on the perovskite precursor to investigate the oxide-phase formation. The structural phase of the powders was determined by X-ray diffraction. These results showed that the decomposition of the precursors occurs in a two-step reaction and temperatures higher that 1000°C are required for these decomposition reactions. For the electrochemical characterization, electrodes were deposited by a wet spray technique on dense yttria-stabilized zirconia (YSZ) layers. The morphology of the deposited perovskite thick films was investigated by field emission scanning electron microscopy and showed a porous microstructure. Electrochemical impedance spectroscopy (EIS) measurements were carried out under synthetic air flux at temperatures ranging from 200-600°C in the 10 mHz-10 MHz frequency range showing an interfacial electrical resistance related to the electrodes. EIS measurements were also performed in the same frequency range at different oxygen partial pressures at 600°C. At this temperature and frequencies below 0.1 MHz, the electrical response to the applied signal of the electrode material is best fitted by two semicircles, which can be related to charge-transfer processes. The activation energy for the limiting step (adsorption/desorption) was found to be 1.6 eV. © 2004 The Electrochemical Society. All rights reserved.