Synthesis of plutonium trichloride and measurement of redox potentials for the Pu3+/Pu0 couple in NaCl–2CsCl melt

Plutonium trichloride (PuCl3) was synthesized by a solid-state reaction of plutonium nitride with cadmium chloride. Electrochemical studies of PuCl3–(NaCl–2CsCl) melt at 823–923 K revealed that Pu3+ ions are reduced to Pu metal by a single-step mechanism and that the apparent standard potentials of the Pu3+/Pu0 redox couple are given by E*(Pu3+/Pu0) = − 3.514 + 8.60 × 10−4 T vs. Cl2/Cl− (V). The activity coefficients of Pu3+ ions were determined using the previously reported Gibbs free energy of formation for PuCl3 in the supercooled liquid state.