Structural and electrochemical properties of the Sr0.8Ce0.1Fe0.7Co0.3O3-δ perovskite as cathode material for ITSOFCs

Powders of the perovskite of nominal composition Sr0.8Ce0.1Fe0.7Co0.3O3-delta (SCFC) were prepared by a modified citrate route in order to determine its structural and micro structural characteristics. In this study, the interpretation of the X-ray diffraction has been performed based on a diagonal perovskite. However, electron diffraction demonstrates that the microstructure is rather more complex than that deduced from the average cell root2a(p) x 2a(p) x root2a(p). Two reflections in the selected area electron diffraction may be interpreted as first-order satellites, of different basic reflections, arising from an incommensurate modulation along the b* direction (b approximate to 2.4a(p) Angstrom). Symmetrical electrodes of Sr0.8Ce0.1Fe0.7Co0.3O3-delta powders were deposited on Ce0.9Gd0.1O1.95 (CGO) ceramic pellets, and the electrochemical properties of the interfaces between the porous cathodes (SCFC) and the electrolyte (CGO) have been investigated at intermediate temperatures (500-766 degreesC) using AC impedance spectroscopy. SCFC electrodes exhibited an area-specific resistivity (ASR) at 700 degreesC of 0.86 Omega cm(2). The behaviour of the perovskite cathodes was interpreted in terms of available oxygen ion kinetic data. (C) 2002 Elsevier Science B.V All rights reserved.