Sintering, transport properties and thermal expansion of Cr-deficient Nd0.75Sr0.25Cr1−δO3 solid solutions

Chromium-deficient Nd0.75Sr0.25Cr1−δO3 (0.02 ≤ δ ≤ 0.06) solid solutions were prepared using a conventional solid-state reaction. The effects of chromium-deficiency content on sintering, transport properties and thermal expansion of the solid solutions were investigated. The results showed that all the solid solutions present single phase orthorhombic perovskite structure at room temperature. The cell volume and the electrical conductivity of Nd0.75Sr0.25Cr1−δO3 solid solutions decrease with the increase of Cr vacancy content. The Nd0.75Sr0.25Cr0.98O3 sample exhibits the best properties. The relative density is 95.5%, and the electrical conductivity and thermal expansion coefficient (TEC) reach 18.8 S cm−1 at 850 °C and 9.62 × 10−6 K−1 in the temperature range of 30-1000 °C in air, respectively. Compared with Nd0.75Sr0.25CrO3, TEC of the Nd0.75Sr0.25Cr0.98O3 sample is more compatible with that of yttria stabilized zirconia (10.3 × 10−6 K−1). Sintering, electrical and thermal expansion properties all indicate that Nd0.75Sr0.25Cr0.98O3 can be a promising candidate for interconnect material application in solid oxide fuel cells.