Synthesis, characterization and sinterablity of 10 mol% Sm 2O 3-doped CeO 2 nanopowders via carbonate precipitation

Abstract

A carbonate coprecipitation method has been used for the facile synthesis of highly reactive 10 mol% Sm 2O 3-doped CeO 2 (20SDC) nanopowders, employing nitrates as the starting salts and ammonium hydrogen carbonate (AHC) as the precipitant. The AHC/RE 3+ (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 Ce 0.8Sm 0.2(CO 3) 1.5·1.8H 2O, 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 4 h.