Hydrothermal Synthesis of Nanocrystalline Cerium(IV) Oxide Powders

Nanocrystalline cerium(IV) oxide (CeO 2 ) powders were prepared by heating solutions of cerium(IV) salts in the presence of urea under hydrothermal conditions at 120° to 180°C. The effects of the concentration of urea and hydrothermal treatment temperature on the morphology and crystallite size of the synthesized particles were investigated. The synthesized particles were angular, ultrafine CeO 2 , with a cubic fluorite structure. Their crystallite size decreased from 20 to 10 nm with increasing urea concentration from 2 times to 8 times that of the Ce 4+ ion. The size only slightly changed by calcining at temperatures below 600°C.