Charge Distribution in U_1-CeO₂₊ Nanoparticles

In view of safe management of the nuclear wastes, a sound knowledge of the atomic-scale properties of U_1-MO₂₊ nanoparticles is essential. In particular, their cation valences and oxygen stoichiometries are of great interest as these properties drive their diffusion and migration behaviors into the environment. Here, we present an in-depth study of U_1-CeO₂₊, over the full compositional domain, by combining X-ray diffraction and high-energy resolution fluorescence detection X-ray absorption near-edge structure. We show, on one hand, the coexistence of U^IV, U^V, and U^VI and, on the other hand, that the fluorite structure is maintained despite this charge distribution.