Thermal removal of gallium from gallia-doped ceria

Abstract The potential for removing gallium from Ga-doped CeO2−x by thermal means was studied for the purpose of assessing gallium removal from PuO2−x. The latter is of interest to those considering the storage or use of weapon-grade Pu, for example as a mixed oxide fuel component. Experiments were done by varying temperature, gas composition, exposure time, sample size, particle size, and gas flow rate. The kinetics of gallium removal were assessed through measurements of weight change, scanning electron microscopy, and chemical analyses. Results suggest that the gallium level can be reduced significantly by thermal treatments in Ar–6% H2. Gallium species segregate to grain boundaries because of the low solubility of Ga2O3 in CeO2. The kinetics and microstructural observations suggest that both gaseous and solid-state diffusion of gallium species are important for the removal of gallium.