Structural and electrochemical properties of the perovskite oxide Pr _0.7Sr_0.3Cr_0.9Ni_0.1O _{3 -δ}

The perovskite oxide Pr_0.7Sr_0.3Cr _0.9Ni_0.1O_{3 -d} was synthesised by a combustion method. Pr_0.7Sr_0.3Cr_0.9Ni _0.1O_{3 -d} obtained at 1400 °C has been shown to have an orthorhombic structure with space group Pnma (62), a=5.4388(1)Å, b = 7.6969(1)Å, c = 5.4584(1)Å, V=228.50(1)ų according to X-ray diffraction. The material is redox stable and maintains its structure in a reducing atmosphere. After reducing in 5% H₂ at 900 °C for 190 h, Pr_0.7Sr_0.3Cr_0.9Ni _0.1O_3-d still exhibits an orthorhombic structure. A lattice volume expansion of 0.61% was observed during the reduction, which may be attributed to reduction of Pr, Cr and Ni ions accompanying loss of lattice oxygen. TGA analysis and EDS indicate Pr_0.7Sr_0.3Cr _0.9Ni_0.1O_{3 -d} shows enhanced resistance to nickel reduction. The conductivities of this material in air and 5% H ₂ were 27.4 and 1.37 S/ cm respectively at 900 °C. Pr _0.7Sr_0.3Cr_0.9Ni_0.1O _{3 -d} exhibits semiconductor behaviour in both air and 5% H ₂. The anode polarisation resistance of Pr_0.7Sr _0.3Cr_0.9Ni_0.1O_{3 -d} reached 0.98 Ocm² at 900 °C in wet H₂ but still not good enough as a good SOFC anode although it could be further improved by optimisation of microstructure. © 2008 Elevier B.V. All rights reserved.