Electrochemical behavior of dysprosium(III) in eutectic LiF-DyF3 at tungsten and copper electrodes

Electrochemical behavior of dysprosium (Dy) ions in LiF-DyF3 (24 mol%) was investigated by cyclic voltammetry, chronoamperometry and chronopotentiometry. Dy-Cu alloy samples were prepared by constant-potential electrolysis in LiF-DyF3 (24 mol%) at the Cu electrode. The Cu5Dy and Cu phases were characterized by an X-ray diffractometer and a scanning electron microscope equipped with an energy dispersive spectrometer. The results show that the reduction of Dy(III) ions in a LiF-DyF3 (24 mol%) molten salt system is found to be a quasi-reversible diffusion-controlled process which occurs via a onestep reaction involving the transfer of three electrons. The electro-crystallization processes of the Dy metal at the W electrode and the mode of nucleation confirm that progressive nucleation is dominant at high concentrations of Dy ions in the LiF-DyF3 salt. At lower concentrations, the instantaneous nucleation of Dy with three-dimensional growth of the nuclei is dominant. (C) 2020 Published by Elsevier B.V. on behalf of Chinese Society of Rare Earths.