ELECTROCHEMICAL BEHAVIOR OF SCANDIUM IN THE LiF–CaF₂–ScF₃ MELT

The electrochemical behavior of scandium in halide melts is of interest both from the point of view of developing new electrochemical methods for producing scandium and its materials, and from the point of view of simulating electrochemical behavior of fission products during pyrochemical processing of spent nuclear fuel in molten salts. Using the methods of cyclic voltammetry, square-wave voltammetry and chronopotentiometry, the regularities of electrical reduction of scandium ions depending on the electrolysis parameters of the LiF–CaF₂–ScF₃ melt at a temperature of 800°C were studied. It is shown that the electrical reduction of scandium in the melt under study occurs at potentials more negative than –0.45 V relative to the potential of the aluminum electrode, while the electrodeposition of scandium on the electrode contributes to the electrical reduction of lithium cations with depolarization. When analyzing the obtained polarization dependences, it was noted that the process of electroreduction of scandium proceeds in one 3-electrode stage, while it is not electrochemically reversible. It has been suggested that the cause of irreversibility is the stage of formation of a new phase. As a result of electrochemical measurements, it was concluded that, due to the wide “electrochemical window”, the LiF–CaF₂ melt can be used both for the electrochemical synthesis of scandium and studying regularities of the selective electroreduction or co-electroreduction of minor actinides and lanthanides.