The valence band electronic structures of mixed uranium oxides (UO ₂ , U ₄ O ₉ , U ₃ O ₇ , U ₃ O ₈ , and β-UO ₃ ) have been studied using the resonant inelastic X-ray scattering (RIXS) technique at the U M ₅ edge and computational methods.

Understanding the melting mechanisms of nanocrystals embedded in solids is of great current interest since both the synthesis and modification of such systems frequently involve the use of high temperatures. Using molecular-dynamics computer simulations we study the melting mechanisms of Cu, Ag, and Au nanoclusters embedded in metal matrices and Si nanocrystals in amorphous silica. The results show that nanocrystals embedded in a solid bulk material with a higher melting temperature exhibit complex melting behavior and can even, in the same system, exhibit four distinct stages prior to full melting of the system.

Proton (H⁺) irradiation effects in polycrystalline UO₂ have been studied. The irradiation was carried out using three ion energies and two different ion fluxes at 600 °C. Scanning electron microscopy (SEM) investigations showed that significant surface flaking took place. Focused ion beam (FIB) milling in SEM was successfully applied for extracting lamellas from uneven blistered surfaces for transmission electron microscopy (TEM) investigations allowing detailed investigations for the degradation mechanisms. High-resolution TEM for the flaked UO₂ surfaces revealed that the implanted H⁺ formed sharp two-dimensional cavities at the peak ion-stopping region instead of diffusing to the matrix. The resulting lateral stress likely caused UO₂ surface deterioration in good agreement with previous blistering and flaking studies on crystalline materials. Graphical abstract