Influence of the synthesis conditions on the crystal structure and properties of GdBaCo2−xFexO5+δ oxides as air-electrodes for intermediate temperature solid oxide fuel cells

Abstract

The influence of the synthesis conditions on the crystal structure and properties of the oxides of the system GdBaCo_2−xFe_xO_5+δ is reported in this article. The materials are prepared by a ceramic method either in air or in an argon atmosphere. Crystal structure characterization is carried out by a combination of powder X-ray diffraction (PXRD) with advanced methods of high resolution transmission electron microscopy (HRTEM), scanning-transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS). Thermal expansion coefficients of the oxides decrease with increasing substitution of Co by Fe. Impedance spectroscopy analysis of symmetrical cells using these materials as electrodes reveals area-specific polarization resistance (ASR) values low enough for the use of the oxides as air electrodes in intermediate temperature solid oxide fuel cells (IT-SOFCs).