What is CeO2

Nanocrystalline cerium(IV) oxide (CeO2) 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 urea concentration and hydrothermal treatment temperature on the morphology and crystallite size of the synthesized particles were investigated. The synthesized particles were angular, ultrafine CeO2 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 Ce4+ ion. The size only slightly changed by calcining at temperatures below 600°C. Undoped CeO2 and Y2O3-doped CeO2 powders, with  ≍10–15 nm particle sizes, were prepared under hydrothermal conditions of 10 MPa at 300 °C for four h. The compacted powders were sintered freely in air or O2 at constant heating rates of 1–10 °C/min up to 1350 °C. The undoped CeO2 started to sinter at ≍800–900 °C and reached a maximum density of 0.95 of the theoretical at 1200 °C, after which the density decreased slightly. Isothermal sintering at 1150 °C produced a sample with a relative density  ≍of 0.98 and an average grain size of ≍100 nm. The samples sintered above 1200 °C exhibited microcracking. The decrease in density and the microcracking above 1200 °C are attributed to a redox reaction leading to the formation of oxygen vacancies and the evolution of O2 gas. Doping with Y2O3 increased the temperature at which measurable sintering commenced and increased the sintering rate compared with the undoped CeO2. Sintered samples of the doped CeO2 showed no microcracks. The CeO2 doped with up to 3 mol% Y2O3 was sintered to almost full density and with a grain size of ≍200 nm at 1400 °C. If you are looking for high quality, high purity and cost-effective CeO2, or if you require the latest price of CeO2, please feel free to email contact mis-asia.