A potential interconnect material for solid oxide fuel cells: Nd0.75Ca0.25Cr0.98O3−δ

Chromium-deficient Nd0.75Ca0.25Cr1−xO3−δ (0.02 ≤ x ≤ 0.06) oxides are synthesized and assessed as a novel ceramic interconnect for solid oxide fuel cells (SOFCs). At room temperature, all the samples present single perovskite phase after sintering at 1600 °C for 10 h in air. Cr-deficiency significantly improves the electrical conductivity of Nd0.75Ca0.25Cr1−xO3−δ oxides. No structural transformation occurs in the Nd0.75Ca0.25Cr1−xO3−δ oxides in the temperature range studied. Among all the samples, the Nd0.75Ca0.25Cr0.98O3−δ sample with a relative density of 96.3% exhibits the best electrical conductivity of 39.0 and 1.6 S cm−1 at 850 °C in air and hydrogen, respectively. The thermal expansion coefficient of Nd0.75Ca0.25Cr0.98O3−δ sample is 9.29 × 10−6 K−1 in the temperature range from 30 to 1000 °C in air, which is close to that of 8 mol% yttria stabilized zirconia electrolyte (10.3 × 10−6 K−1) and other cell components. The results indicate that Nd0.75Ca0.25Cr0.98O3−δ is a potential interconnect material for SOFCs.