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Sodalite, a candidate ceramic for the immobilisation of pyroprocessing nuclear waste, showed no observable lattice dilatation in grazing incidence X-ray diffraction when irradiated with up to 1017 5 MeV He ions/cm². However micro-Raman scattering showed considerable spectral broadening characteristic of radiation damage near the end of the ~22 μm He range. Partial amorphism plus nepheline formation was observed in grazing incidence X-ray diffraction when sodalite was irradiated by 1016 12 MeV Au ions/cm². Nepheline appeared less susceptible to 12 MeV Au ion damage than sodalite, with ~25% less amorphous fraction at 1016 ions/cm². [ABSTRACT FROM AUTHOR]

Abstract: Raman spectra of synthetic non-substituted and U/Np/Pu- substituted thorutite (ThTi2O6) samples were collected. Factor group analysis was used to analyse the possible vibration modes. Theoretical simulations based on density functional theory (DFT) were performed on both CeTi2O6 and ThTi2O6. All possible vibrational modes for thorutite have been identified and assigned to the measured spectra. The presence and the effect of higher valence of U in thorutite has been discussed and the U–O bond lengths have been calculated by using the measured wavenumbers of ν 1 (UO2)2+ symmetric stretching vibrations. The presence of U6+ in uranyl form can be inferred from the wavenumbers of U–O vibrations. Corresponding Np–O and Pu–O vibrations were not observed in the Raman spectra. Thus the presence of Np6+ and Pu6+ in the studied samples was not established. [Copyright &y& Elsevier]