In situ studies of the decomposition of ammonium uranyl carbonate in an electron microscope

Abstract

An electron microscope has been used to study the reduction of ammonium uranyl carbonate (AUC) to UO 2. The reactions could be followed both in the diffraction and the lattice image mode. The first intermediate obtained was amorphous UO 3. Depending on the experimental conditions, either crystalline UO 2 was formed directly from this phase, or several other intermediates were indicated. Properties like crystallinity and crystallite size of final UO 2 were found to be a function of experimental conditions. Comparisons with properties of UO 2 from the industrial process have been made.