Characterization of tantalum doped lanthanum strontium ferrite as cathode materials for solid oxide fuel cells

The phase relations and crystal structures of La1-xSrxFe1-yTayO3 in the compositional range x = 0-0.60, y = 0-0.20 were investigated by powder X-ray diffraction (XRD). The formal concentration of Fe4+ in the La1-xSrxFe1-yTayO3±w (LSFT) system was calculated and related to the electrical/electrochemical properties. To investigate the electrochemical behaviour as cathode material for SOFCs, impedance measurements were performed on LSFT/electrolyte/LSFT symmetrical cells by using La0.8S0.2Ga0.8Mg0.2O3, (LSGM) as electrolyte material. The lowest area specific resistance (ASR), derived from the polarization resistance (Rp), 1 Ω cm2 at 750 °C, was measured for the LSFT compound doped with x = 0.40 and y = 0.05.