Influence of Trivalent-Dopants on the Structural and Electrochemical Properties of Uranium Dioxide (UO2)

The influence of trivalent dopants (rare-earths, RE) on the structure, composition and electrochemical reactivity of UO 2 has been investigated using scanning electron microscopy (SEM/XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and cyclic voltammetry (CV). This was achieved by comparing the behavior of undoped UO 2.002 , a slightly doped 1.5 at% SIMFUEL, and two rare-earth doped UO 2 (6 wt% Gd-UO 2 and 12.9 wt% Dy-UO 2 ) specimens. The reactivity decreased in the order UO 2.002 > SIMFUEL > Dy-UO 2 > Gd-UO 2 , showing that this decrease is a consequence of RE III doping. Raman spectroscopy showed this could be attributed to the formation of RE III – oxygen vacancy clusters whose formation decreases the availability of the vacancies required to accommodate the injection of oxygen interstitials during anodic oxidation. The behavior of SIMFUEL is complicated by the simultaneous formation of RE III - oxygen vacancy clusters and Zr-O 8 clusters.