Characterization of uranium oxides using in situ micro-Raman spectroscopy

A range of uranium compounds have been characterized using micro-Raman spectroscopy. It is possible to easily distinguish the oxides UO2, alpha-U3O8, and gamma-UO3. Studies have also investigated the Raman spectra of uranium precursors used for the preparation of these oxides. In situ studies to probe the transformation of uranyl nitrate to uranium oxide show that the nitrate is decomposed below 300 degrees C. Initially an oxide similar to UO3 is produced, and this oxide gradually transforms to U3O8 as the temperature is increased to 550 degrees C. The use of in situ Raman studies provides a powerful technique to study the mechanism of transformation and the stability of uranium oxides under oxidizing conditions.