Modeling the redox equilibrium of the Ce4+/Ce3+ couple in silicate glass by voltammetry

Square-wave voltammetry was used to determine the characteristic potential of the Ce4+/Ce3+ couple in four glass formulations covering a wide range of silicate glass compositions suitable for nuclear waste containment. The temperature range investigated extended from 1178 K to 1523 K. As the Ce4+/Ce3+ peak potential is situated near the silicate oxidation wall, its position was determined more precisely by superimposing the theoretical peak on voltammetry diagram. The results were then used to develop a model relating the Ce4+/Ce3+ redox ratio to the oxygen fugacity, temperature and optical basicity. In its general expression, the relation accounts for the evolution predicted by the laws of thermodynamics, and is similar to the relations established for the Fe3+/Fe2+ redox couple by other authors.