Control of particle size and shape of precursors for ceria using ammonium carbonate as a precipitant

Spherical nanocrystalline precursors of ceria (CeO2) and CeO2 powder with different size distributions were prepared by a reflux method using cerium nitrate hexahydrate (CN) as the cerium source and ammonium carbonate (AC) as the precipitant. The crystalline phases of the synthesized CeO2 precursors were identified as orthorhombic Ce2O(CO3)2 center dot H2O and hexagonal CeCO3OH. The particle size and shape could be easily controlled by the CN concentration and the ratio of [AC]/[CN]. The CeO2 precursors were calcined at 400-700 degrees C to obtain CeO2. The particle size distribution and morphology of the synthesized CeO2 powders were unaffected by the calcination. The specific surface area of the CeO2 powders was increased by the release of CO2 and H2O during the calcination. The calcination temperature is an important factor for the preparation of CeO2 powder with a high surface area. (C) 2009 Elsevier B.V. All rights reserved.