Structure, electrical conducting and thermal expansion properties of La0.6Sr0.4Co0.8Fe0.2O3−δ–Ce0.8Sm0.2O2−δ composite cathodes

The structure, electrical conducting and thermal expansion properties of La0.6Sr0.4Co0.8Fe0.2O3−δ–Ce0.8Sm0.2O2−δ composite cathodes have been investigated with respect to the fraction of Ce0.8Sm0.2O2−δ electrolyte. No chemical reaction product between the two constituents was detected for the composite cathodes sintered at 1200 °C for 4 h. A dense microstructure composing of homogeneously distributed constituent phases was observed. It was found that the electrical conducting and thermal expansion properties of the composite cathodes are sensitive to the fraction of Ce0.8Sm0.2O2−δ electrolyte. In terms of both electrical conducting and thermal expansion properties, the composite cathode containing 50 wt.% Ce0.8Sm0.2O2−δ electrolyte was ascertained to be the optimum composition. This composition offers sufficiently high electrical conductivities of 100–116 Ω−1 cm−1 at intermediate temperatures (600–800 °C) and a moderate thermal expansion coefficient of 14.4 × 10−6 K−1 averaged between 100 and 730 °C.