Abstract:

Samaria-doped ceria(Sm_0.2Ce_0.8O_1.9, SDC) is a promising candidate material for electrolyte of intermediate temperature(600—800 ℃) solid oxide fuel cells(IT-SOFCs). SDC powders were synthesized by a combustion method with urea as a fuel. The phase purity and morphology of the resulting powders were characterized by XRD, TG-DSC, FESEM and BET specific surface area measurement. Moreover, the sinterability and electrical conductivity of the SDC were examined. The results demonstrate that the urea-combustion process is a simple and efficient route to produce high reactive SDC powder. It was found that the SDC powder with a pure cubic fluorite phase could be produced via a short-time combustion process. The SDC powder is composed of uniform and dispersed sphere-like particles in the range of 50—150 nm. This desired morphology effectively enhanced the sinterability of the powder. A gas-tight relative density of 95.1% was obtained in the SDC ceramic sintered at a relative low temperature of 1250 ℃. Furthermore, the ceramic sintered at the temperature presented superior electrical conductivity, reaching 5.4×10^-2 and 1.0×10^-1 Ω^-1·cm^-1 at the measuring temperatures of 600 and 800 ℃, respectively.

Key words: Ce_0.8Sm_0.2O_1.9; Oxygen ionic conductor; Combustion synthesis; Urea