Abstract
The Fe‐doped cobaltates, 
, were prepared and their high‐temperature phase stability and cathodic activity were investigated. The perovskite/yttria‐stabilized zirconia (YSZ) electrodes were fabricated via a silk printing technique. It was found that the undoped cobaltate (x = 0) is so thermally unstable that the preparation of pure perovskite phase was unsuccessful. The partial Fe‐doping to Co (x = 0.1–0.7), however, gave us highly crystalline perovskite powders of an orthorhombic lattice. Among those samples of x = 0.1–0.7, the 
showed the best cathodic activity which is superior to 
. The thermal expansion coefficient of this material 
was very close to that of 8 mol % YSZ 
. As a result of interfacial reaction between 
and YSZ electrolyte, a spinel‐type oxide was produced. But the interfacial product formation proceeded mainly during the electrode adhesion period (1200°C) whereas its growth during the cell operation (900–1000°C) was negligible. © 1999 The Electrochemical Society. All rights reserved.