Effect of the synthesis conditions on the properties of La0.15Sm0.35Sr0.08Ba0.42FeO3-a cathode material for SOFCs

The perovskite La0.15Sm0.35Sr0.08Ba0.42FeO3-a has been prepared by the glycine nitrate (GNC) route, varying the fuel/oxidizer ratio (glycine/nitrate, G/N= 1 and 2) and cooling rate (slow cooling and air-quenched), in order to study the influence of sample preparation on the materials’ properties, in the context of their application as a cathode material for SOFCs. For this, the performance of the prepared mixed ion and electron conducting perovskite oxides is dictated by their structure, oxygen stoichiometry (3-δ), chemical composition and thermal expansion properties. High-resolution Synchrotron X-ray powder diffraction patterns were collected at room temperature and at 700 and 800ºC. It was found that the materials had a cubic crystal structure at these temperatures. As expected, 3-δ decreased as temperature increased, and was slightly smaller for the quenched sample. Higher electrical conductivity values were obtained for the sample with G/N = 1 (air-quenched) in the cooling rate. At 700 and 800°C the cathode synthesized with G/N = 1 and air-quenched showed the smallest polarization resistance values in impedance spectroscopy studies. Therefore, the physicochemical and electrochemical characterization clearly demonstrated the influence of the synthetic conditions on the cathode performance.Ministerio de Economía, Industria y Competitividad (MAT2016-76739-R (AEI/FEDER, UE) and MAT2015-86078-R), and Departamento de Educación of the Basque Government (IT-630-13