Synthesis and properties of La_0.6Sr_0.4CoO_3-δ nanopowder

Uniform nanopowders of La_0.6Sr_0.4CoO_3-δ (LSC) were synthesized by the combined citrate-EDTA method. The precursor solution was prepared from nitrates of the constituent metal ion, citric acid and EDTA with a pH value controlled by ammonia. The obtained product was characterized by TG/DTA, XRD, SEM, and BET measurements. The single perovskite phase could form completely after sintering at the temperature of 900 °C. There was no significant effect of the precursor solution pH value on the perovskite phase formation temperature; however, LSC powders prepared from the precursors with different pH values showed specific shapes. The morphology of La_0.6Sr_0.4CoO_3-δ powder was also optimized with proper surfactant addition. The sintered La_0.6Sr_0.4CoO_3-δ bulk samples exhibited an electrical conductivity of 1867 S cm^-1 in air at 800 °C. The impedance spectra of a symmetric LSC cathode on a GDC electrolyte substrate were measured and polarization resistance (R_p) values of 0.17 Ω cm² at 700 °C and 0.07 Ω cm² at 750 °C in air were obtained.