A study of Pr_0.7Sr_0.3Fe_1-xNi _xO_3-δ as a cathode material for SOFCs with intermediate operating temperature

Pr_0.7Sr_0.3Fe_1-xNi_xO _3-δ(PSFN; x=0.2-0.5) compounds were synthesized and characterized by powder X-ray diffraction (XRD), thermal expansion coefficient (TEC) measurements, electrical conductivity and electrochemical impedance spectroscopy on cone-shaped electrodes on a Ce_0.9Gd _0.1O_1.95 (CGO10) electrolyte. The main phase of the powders belongs to the orthorhombic crystal system. The conductivities are fairly high, e.g., around 450 Scm^-1 at 600 °C for the x=0.3 compound. The TEC of the compounds is close to the values of ceria-based electrolytes. PSFN showed hysteresis in the temperature dependence of the conductivity, TEC and area-specific polarization resistance R_pol. It is considered that the hysteresis was caused by relatively slow adjustment of the oxygen stoichiometry. The electrochemical performance R_pol ^-1 of the PSFN compounds is similar to that of La _0.6Sr_0.4Fe_0.8Co_0.2O _3-δ.