Synthesis and characterization of strontium and iron-doped lanthanum cobaltite nanocrystalline powders for single chamber solid oxide fuel cells

Different sets of perovskite-type oxides of general formula La _0.8Sr_0.2Co_1-xFe_xO₃ (0.0 < × < 1.0) were successfully prepared by the amorphous citrate method. Simultaneous thermogravimetric and differential thermal analysis (TG-DTA) was carried out on the precursor gels to determine the minimum temperature of the oxide formation, which was found to be 600°C. After thermal treatments, samples were characterized by using Induced Couple Plasma (ICP) spectroscopy, X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). Single-phase nanocrystalline powders were obtained with controllable grain size from 10 to 20 run as a function of the iron ratio. ICP results indicate that for the prepared samples the actual metal contents were nearly equal to the nominal values. XRD results showed that La_0.8Sr _0.2Co_1-xFe_xO₃ compounds possess a rhombohedral to orthorhombic structure, depending on the iron content. Moreover, the perovskite-type nano-powder oxides were characterized as electrodes on Ce_0.8Sm_0.2O_2-x pellets in symmetrical cells, and the electrochemical properties of the electrode/electrolyte interfaces were investigated using electrochemical impedance spectroscopy (EIS).