Electrochemistry of Neodymium in an Equimolar NaCl-KCl Melt without and with Addition of Fluoride Ions

Abstract

The paper presents results of neodymium electrochemical behavior in chloride and chloride-fluoride melts. It was shown that the process of neodymium electroreduction in the NaCl-KCl-NdCl3 melt proceeds in two stages. It was established by diagnostic criteria of voltammetry that the discharge process of Nd(III) to Nd(II) at a sweep rate in the range of 0.6 ≤ n ≤ 1.0 V s-1 is not complicated by reaction disproportionation. In this study diffusion coefficients, activation energy of diffusion for Nd(III) complexes and standard rate constants of charge transfer for the Nd(III)/Nd(II) redox couple in the NaCl-KCl melt were determined. It was shown that the addition of fluorine anions into the NaCl-KCl-NdCl3 melt leads to stabilization of the higher oxidation state of neodymium in chloride-fluoride melts and neodymium in the intermediate oxidation state +2 in these melts does not exist.