Abstract
Raman spectra of three NpO2 samples and two samples produced from a modified direct denitration (MDD) process were collected. The spectral features of the NpO2 samples were consistent and indicated only NpO2. The spectra of the MDD samples indicated the presence of NpO2 and an additional phase attributed to the neptunium binary oxide Np2O5. These Raman spectra are the first reported of Np2O5, and the proportions of these neptunium oxide phases varied within the samples, suggesting significant sample inhomogeneity. Peaks in the Raman spectra of Np2O5 at 569 and 782 cm−1 were tentatively assigned to concerted, symmetric stretches of the neptunyl cations. Laser-induced heating of regions in the MDD samples that were rich in Np2O5 showed spectral features that indicated conversion to NpO2.
