Study on the preparation of Ce_0.8Sm_0.2O_1.9 by nitrate-citric acid method and its performances

Ce_0.8Sm_0.2O_1.9(SDC) nano powders were synthesized by nitrate-citric acid method. XRD patterns show that SDC powders calcined at various temperatures have a cubic fluorite structure, and the average grain size is between 5.4-24.3 nm. TEM results reveal that SDC particles are spherical in shape and have even grain size distribution. Particle size distribution shows that there exists obvious aggregation in SDC powder system for its high activity. TGA-DSC results show that the decomposition process of dried gel can be finished below 400°C. For SDC powder calcined at 800°C for 2 h, the sintering shrinkage begins at 641.1°C and the total shrinkage is about 11.1% after sintered at 1300°C for 2 h. The conductivity of SDC solid electrolyte sintered at 1400°C for 10 h is 2.02 × 10^-2 S·cm^-1 and 0.197 S·cm^-1 at 600°C and 800°C respectively, and the ionic conducting activation energy is 104.2 kJ·mol^-1. The conductivity in hydrogen is about two times of that in air.