Influence of Cr deficiency on sintering character and properties of SOFC interconnect material La0.7Ca0.3Cr1−xO3−δ

The SOFC interconnect materials La0.7Ca0.3Cr1−xO3−δ (x = 0–0.09) were prepared using an auto-ignition process and characterized. XRD analysis indicated that all the samples displayed a pure perovskite phase after sintered at 1400 °C for 4 h. The relative density increased from 67% (x = 0) to 95.8% (x = 0.02) and reached to about 97% (x > 0.02), as sintered at 1400 °C for 4 h. The electrical conductivity in air dramatically increased and then lowered slowly with x values. The sample with 0.03 Cr deficiency got a maximum conductivity of 61.7 S cm−1 at 850 °C in air, which is about three times as high as that of the sample with no Cr deficiency (20.6 S cm−1). The sample with 0.06 Cr deficiency exhibited the highest electrical conductivity of 3.9 S cm−1 at 850 °C in pure H2. The thermal expansion coefficient (TEC) were below 11.8 × 10−6 K−1 for samples of x = 0.02–0.09, that was of well compatibility with other components in SOFCs. Results indicate that the materials with 0.02–0.06 Cr deficiency have high properties and are much suitable for SOFC interconnect.