Synthesis, characterization and sinterablity of 10mol% Sm2O3-doped CeO2 nanopowders via carbonate precipitation

A carbonate coprecipitation method has been used for the facile synthesis of highly reactive 10mol% Sm2O3-doped CeO2 (20SDC) nanopowders, employing nitrates as the starting salts and ammonium hydrogen carbonate (AHC) as the precipitant. The AHC/RE3+ (RE=Ce+Sm) molar ratio (R) and the reaction temperature (T) affect significantly the final yield and precursor properties, including chemical composition and particle morphology. Suitable processing conditions are T=60°C and R=5.0–10, under which precipitation is complete and the resultant precursors show ultrafine particle size, spherical particle shape, and good dispersion. Thus, the processed precursors are rare-earth carbonates with an approximate formula of Ce0.8Sm0.2(CO3)1.5·1.8H2O, which directly yield oxide solid-solutions upon thermal decomposition at a low temperature of ∼440°C. The 20SDC solid solution powders calcined at 700°C show excellent reactivity and have been densified to ∼99% of the theoretical via pressureless sintering at a very low temperature of 1200°C for 4h.