Chemistry of uranium in aluminophosphate glasses

The U(VI)-U(V)-U(IV) redox equilibria were monitored in two sodium aluminophosphate base compositions at a variety of melt temperatures, imposed oxygen fugacities, and uranium contents. The higher redox states of uranium were quite soluble in the phosphate glasses, whereas U(IV) would readily precipitate from the melts as UO2. Comparisons of the uranium redox equilibria established in phosphate melts vs those in silicate melts indicated that the coordination sites of the individual uranium species are generally the same in both solvent systems although they differ in detail