Single solution spray pyrolysis of La0.6Sr0.4Co0.2Fe0.8O3 − δ–Ce0.8Gd0.2O1.9 (LSCF–CGO) thin film cathodes

Abstract

Thin film (200–300nm) (X)La0.6Sr0.4Co0.2Fe0.8O3−δ–(1−X)Ce0.8Gd0.2O1.9 (LSCF–CGO, X=0 to 100 vol.%) composite cathodes were produced by spraying a single precursor solution of nitrate salts onto dense yttria stabilized zirconia electrolyte substrates at temperatures of 235 and 275°C. Segregation of the films into distinct LSCF and CGO phases was observed by X-ray diffraction after annealing above 650°C for 4h. Grain growth was suppressed in the LSCF–CGO composites relative to pure LSCF, the grain size in 59LSCF–41CGO ranging from 15 to 50nm for annealing temperatures between 700 and 900°C. The polarization resistance of films fired at 700°C were modeled using a Gerischer impedance with a characteristic polarization resistance Rc and time constant tc. Relative to pure LSCF films, the LSCF–CGO composites exhibited lower activation energies resulting in a smaller polarization resistance at operating temperatures below 600°C.