Combustion synthesis and characterization of Pr_0.8Sr _0.2Co_1-xF_xO₃ nanocrystalline powders

Different sets of perovskite-type oxides of general formula Pr _0.8Sr_0.2Co_1-xFe_xO₃ (x = 0.0, 0.2, 0.5, 0.8 and 1.0) were successfully prepared by the amorphous citrate method and auto-combustion synthesis at low temperature. Simultaneous thermogravimetric and differential thermal analysis (TG-DTA) was carried out on dried precursor gels to determine the perovskite-phase formation process, and thus discriminate the ignition temperature, actual combustion temperature, and temperature synthesis of the oxide. The calcination behaviour was studied at temperatures up to 1273 K. Single-phase nanocrystalline powders were obtained with controllable grain size from 30 to 100 nm as a function of the heating. Induced couple plasma (ICP) spectroscopy results indicated that for the prepared samples the actual metal contents were nearly equal to the nominal values. X-Ray diffraction (XRD) results showed that Pr_0.8Sr _0.2Co_1-xFe_xO₃ as-combusted compounds possessed a rhombohedral to orthorhombic structure, depending on the iron content. Composition dependence of lattice constants was observed to follow the Vegard's law. 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). copyright The Electrochemical Society.