Structural, thermal, and electrical properties of A-site double-lanthanide La1-xGdxBaCo2O5+δ ceramics

The perovskite ceramics La 1- x Gd x BaCo 2 O 5+ δ with double lanthanide at A site was synthesized by a traditional solid phase reaction method. The structure and properties of La 1- x Gd x BaCo 2 O 5+ 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 Gd 3+ content. Refined by Rietveld method, it is found that with the increase of Gd, the crystal structure of La 1- x Gd x BaCo 2 O 5+ 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 La 1- x Gd x BaCo 2 O 5+ δ ceramics shows good toxicity resistance in CO 2 and good thermal compatibility with Ce 0.9 Gd 0.1 O 2- 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 LaBaCo 2 O 5+ δ (LBCO) and GdBaCo 2 O 5+ δ (GBCO). Combined with the thermal expansion test and the electrochemical AC impedance analysis, it is found that the thermal expansion coefficient (TEC) of La 0.5 Gd 0.5 BaCo 2 O 5+ 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).