Nano-sized Pr_0.8Sr_0.2Co_1-xFe _xO₃powders prepared by single-step combustion synthesis for solid oxide fuel cell cathodes

Different sets of perovskite-type oxides of general formula Pr _0.8Sr _0.2Co _1-xFe _xO _3-δ (x=0.0, 0.2, 0.5, 0.8 and 1.0) were successfully prepared by low-cost single-step combustion synthesis at low temperatures based on the auto-ignition reaction of a nitrate solution in the presence of citric acid. Thermogravimetric and differential thermal analysis was carried out on nitrate-citrate precursors to determine the perovskite-phase formation process. The results revealed that the nitrate-citrate precursor exhibited self-propagating combustion behavior. Pr _0.8Sr _0.2Co _1-x Fe _xO _3-δ powders showed an orthorhombic single-phase, with their unit cell volume increasing as a function of the Fe content (x). Scanning electron microscopy observations showed that the prepared powders were nanocrystalline. The Pr _0.8Sr _0.2Co _1-xFe _xO _3-δ powders were characterized as fuel cell electrodes on Ce _0.8Sm _0.2O _2-δ pellets in symmetri-cal cells, and the electrochemical properties of the elec-trode/electrolyte interfaces were investigated using electrochemical impedance spectroscopy (EIS) as a func-tion of the temperature, Fe content (x) and oxygen partial pressure.