Structural, thermal, and electrical properties of A-site double-lanthanide La1-Gd BaCo2O5+ ceramics

The perovskite ceramics La1-xGdxBaCo2O5+δ with double lanthanide at A site was synthesized by a traditional solid phase reaction method. The structure and properties of La1-xGdxBaCo2O5+δ were investigated by experiment and analysis. It can be seen from the X-ray diffraction (XRD) that the crystal structure changes from single perovskite to double perovskite with the increase of Gd3+ content. Refined by Rietveld method, it is found that with the increase of Gd, the crystal structure of La1-xGdxBaCo2O5+δ oxides changes from cubic phase for x = 0 to tetragonal phase for x = 0.5 and then to orthorhombic for x = 1.0. The La1-xGdxBaCo2O5+δ ceramics shows good toxicity resistance in CO2 and good thermal compatibility with Ce0.9Gd0.1O2-δ (GDC) at 1100 °C. Through the X-ray photoelectron spectroscopy (XPS) test, it is found that this series of ceramic materials have good oxygen catalytic reduction activity, and the electronic conductivity is better than LaBaCo2O5+δ (LBCO) and GdBaCo2O5+δ (GBCO). Combined with the thermal expansion test and the electrochemical AC impedance analysis, it is found that the thermal expansion coefficient (TEC) of La0.5Gd0.5BaCo2O5+δ (LG-55) is closer to that of GDC electrolyte than LBCO, and the specific area resistance is smaller than GBCO. All these findings indicate that it can be used as a potential cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC).