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

The phase relations and crystal structures of La1xSrxFe1yTayO3 in the compositional range x ¼ 0e0.60, y ¼ 0e0.20 were investigated by powder X-ray diffraction (XRD). The formal concentration of Fe4þ in the La1xSrxFe1yTayO3±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 La0.8Sr0.2Ga0.8Mg0.2O3, (LSGM) as electrolyte material. The lowest area specific resistance (ASR), derived from the polarization resistance (Rp), 1 U cm2 at 750 C, was measured for the LSFT compound doped with x ¼ 0.40 and y ¼ 0.05