Raman Spectra of U ₃ Ox

ABSTRACT Uranium dioxide (UO 2 ) supports the incorporation of oxygen into the fluorite space group up to UO 2.25 . The precise stoichiometry of UO is determinable via Raman spectroscopy. Here, we present methods to use Raman spectroscopy to determine the stoichiometry of the intermediate calcination products between UO 2 and U 3 O 8 via analysis of a series of U 3 O samples. Unlike UO 2 , U 3 O 8 does not appear to support intermediate phases between . Instead, we show that the stoichiometry of intermediate compounds can be determined by monitoring the ratios of the UO 2 and 2LO Raman peaks to the primary peak at 430 cm −1 in U 3 O 8 or by analyzing the spectral variability across a sufficiently large sample of point spectra. Determining the stoichiometry of incompletely oxidized U 3 O 8 using microspectroscopy methods has applications in nuclear forensics, material aging, and fuel monitoring.