Structural and electrochemical properties of the Sr 0.8Ce 0.1Fe 0.7Co 0.3O 3− δ perovskite as cathode material for ITSOFCs

Abstract

Powders of the perovskite of nominal composition Sr 0.8Ce 0.1Fe 0.7Co 0.3O 3− δ (SCFC) were prepared by a modified citrate route in order to determine its structural and microstructural 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 √2 a p×2 a p×√2 a 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≈2.4 a p Å). Symmetrical electrodes of Sr 0.8Ce 0.1Fe 0.7Co 0.3O 3− δ powders were deposited on Ce 0.9Gd 0.1O 1.95 (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 °C) using AC impedance spectroscopy. SCFC electrodes exhibited an area-specific resistivity (ASR) at 700 °C of 0.86 Ω cm 2. The behaviour of the perovskite cathodes was interpreted in terms of available oxygen ion kinetic data.