An original precipitation route toward the preparation and the sintering of highly reactive uranium cerium dioxide powders

The behavior of U1−xCexO2⋅nH2O versus temperature was investigated in a second part. If the increase of the heat temperature allowed one to observe an improvement of the crystallization state linked with the growth of crystallites, it was also accompanied by a strong decrease of the powders reactivity. On this basis, sintering tests were conducted in reducing atmosphere on the compounds as prepared. Dilatometry experiments indicated a low densification temperature compared to other ways of preparation reported in the literature. Also, the pellets prepared after firing at different temperatures (1350-1550 °C) showed that a wide range of microstructures was achievable. Particularly, bulk materials with densities of 90-95% of the calculated value could be prepared with average grain size ranging from around 100 nm to more than 5 μm. This simple process of elaboration of dense materials from highly reactive hydrated oxide precursor thus appears as a very interesting way to prepare actinide oxides materials.