Low temperature processing of dense samarium-doped CeO2 ceramics: sintering and grain growth behaviors Original Research Article

Samarium-doped CeO2 is a leading electrolyte for applications in solid oxide fuel cells (SOFCs), which requires a typical sintering temperature of 1400–1600 °C. By synthesizing reactive powders via carbonate precipitation, fully dense CeO2 ceramics doped with 0–20 at.% of samarium have been fabricated in this work via pressureless sintering at a significantly lowered temperature of 1000 °C. The resultant ceramics show ultrafine grain sizes of ∼0.15–0.75 μm, depending upon the dopant concentration. Sintering studies indicated that samarium doping retards both densification and grain growth but increases the rate ratios of the two in the intermediate stage of sintering. Subsequent investigations on the grain growth in the fully densified ceramics also showed the suppressing effects of dopant, which tend to saturate at 10 at.% of samarium. The activation energy for grain growth increased from ∼186 to ∼254 kJ/mol by raising the samarium concentration from 5 to 20 at.%.