Plutonium chemical properties in NaCl–KCl and CaCl2 at 1073 K

The electrochemical properties of plutonium have been studied in molten equimolar NaCl/KCl and CaCl2 at 1073 K by cyclic voltammetry. The respective standard potentials of Pu(III)/Pu redox couple, −2.54 V and −2.51 V (versus Cl−/Cl2 reference electrode), led to the calculation of the activity coefficients of Pu(III) in each electrolyte. In CaCl2 the complexation of Pu(III) ions is lower and the voltage gap between Pu(III)/Pu redox system and the solvent limit is higher. Use of these results to construct potential–pO2− diagrams for plutonium at 1073 K gives a rational overview of plutonium properties in these media.