Rare-earth-doped ceria powders with a composition of Ce0.8R0.2O1.9 (R=Yb, Y, Gd, Sm, Nd and La) were prepared by heating the oxalate coprecipitate. The green compacts began to shrink at 600 o~700oC. The relative density after the sintering at 1200 o and 1400oC became higher for the higher green density. The samples were densified above 98% relative density by the sintering at 1600oC for 4 h and the grain sizes (4.7~7.6 µm) showed a tendency to become larger with increasing ionic radius of doped- rare-earth element. In the initial stage of sintering at 700 o~800oC, the dominant mass transport process changed from lattice diffusion to grain boundary diffusion with heating time. The porosity during the intermediate and final stage of the sintering at 1200o and 1400oC decreased by the mass transport through lattice diffusion with grain growth.

Keywords: Ceria, Rare-earth-doped, Sintering, Densification, Microstructure, Grain grwoth, Lattice diffusion, Grain boundary diffusion