Formation and microstructural variation of cerium carbonate hydroxide prepared by the hydrothermal process

Crystallized cerium carbonate hydroxide (CeCO3OH) powders have been fabricated successfully via a newly developed hydrothermal process. Comparing with the traditional precipitation method, the reaction time for synthesizing CeCO3OH under the hydrothermal condition is remarkably shortened. The hydrothermally derived CeCO3OH powders exhibit a rhombic shape with an aspect ratio of around 4-5. The aspect ratio of CeCO3OH powders increases slightly with prolonging reaction time. Based on the thermal analysis, a phase transformation from orthorhombic CeCO3OH into cubic fluorite CeO2 is confirmed to take place at around 250 degreesC. Fine CeO2 powders are obtained after quenching the CeCO3OH powders during heat treatment. The formation of fine CeO2 powders is attributed to the rapid decomposition reaction and resultant thermal stress in quenching treatment. (C) 2002 Elsevier Science B.V. All rights reserved.