Thermal expansion matching of Gd1−xSrxCoO3−δ composite cathodes to Ce0.8Gd0.2O1.95 IT-SOFC electrolytes

The thermal expansion match of the Gd1−xSrxCoO3−δ system to the Ce0.8Gd0.2O1.95 IT-SOFC electrolyte material was examined for x=0 to 0.5. Thermal expansion was measured using dilatometry and a large mismatch in thermal expansion was found. Electrical conductivity was found to exceed 300 S cm−1 in all compositions prepared. The Sr content in the Gd1−xSrxCoO3−δ perovskite was maintained at x=0.2 for subsequent thermal matching studies. Ce0.8Gd0.2O1.95 additions to the cobaltite material resulted in stable composite cathode materials that showed little interaction among their constituent phases according to X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. High electrical conductivity was maintained for compositions with excellent thermal expansion matching to the IT-SOFC electrolyte material Ce0.8Gd0.2O1.95.