Oxidation State Shift of Uranium during U(III) Synthesis with Cd(II) and Bi(III) in LiCl–KCl Melt

Synthesis of U3+with Cd2+or Bi3+was investigated in a LiCl–KCl eutectic melt at 500°Cby using cyclic voltammetry (CV) and ultraviolet-visible (UV-vis) spectroscopy. CV results showed that the equilibrium potentials of the species are larger in sequence of U0/3+<Cd0/2+<U3+/4+<Bi0+/3+. UV-vis spectroscopy results exhibited that U3+was directly produced in the eutectic melt containing Cd2+. In BiCl3, U metal was oxidized to U4+by Bi3+, and then U4+was reduced to U3+by additional U. From these results, the reaction mechanisms taking place during the synthesis are proposed.