An electrochemical study of samarium ions in the molten eutectic LiCl + KCl

The electrochemical properties of samarium in LiCl + KCl eutectic melt were investigated at different temperatures. The stable oxidation states of samarium have been found to be (III) and (II) in the melt. The study of the Sm(II)/Sm(0) reaction was not feasible under these conditions, since its redox potential is in the same range of the solvent couple, Li(I)/Li(0). Transient electrochemical techniques, such as cyclic voltammetry, were used in order to determine the standard potential of the redox couple Sm(III)/Sm(II), the activity coefficient and the enthalpy and entropy of formation of SmCl3 in the eutectic melt. Mass transport towards the electrode is a simple diffusion process, and the diffusion coefficients have been calculated. The validity of the Arrhenius law was also verified.