Electrochemical Formation of Nd–Ni Alloys in Molten CaCl₂–NdCl₃

Abstract

The electrochemical formation of Neodymium–Nickel (Nd–Ni) alloys was investigated in a molten CaCl2–NdCl3 (1.0 mol%) system at 1123 K. Cyclic voltammograms for Molybdenum (Mo) and Ni electrodes showed the electrodeposition/dissolution of metallic Nd and the formation/dissolution of Nd–Ni alloys, respectively. The equilibrium potential of Nd3+/Nd was determined at 0.27 V (vs. Ca2+/Ca) by open-circuit potentiometry for a Mo electrode. The potentials of 0.48, 0.68, and 0.95 V, corresponding to the two-phase coexisting states of (NdNi2 + NdNi3), (NdNi3 + NdNi5), and (NdNi5 + Ni), respectively, were confirmed using energy-dispersive X-ray spectroscopy and X-ray diffraction of the Ni electrode electrolyzed samples. The optimum electrolysis conditions for the Nd and Dysprosium (Dy) separation were discussed, and the standard Gibbs energies of formation were calculated for Nd–Ni alloys.

Highly Efficient and Precise Electrolysis Separation of Dysprosium from Neodymium for Magnet Scrap Recycling in Molten Salt

“…Figure 1 shows cyclic voltammograms for a Ni electrode before (blank) and after the addition of 1.0 mol % NdCl 3 (blue) or DyCl 3 (red) at 1123 K. In the cathodic direction scanning, compared with the blank measurement, the cathodic current density increased from around 0.9 V (vs Ca 2+ /Ca) in the NdCl 3 -containing system. According to our previous study, 23 the increase in cathodic current density in this potential region corresponds to the formation of the NdNi 5 alloy. In addition, the cathodic current further increased from around 0.5 V, indicating the formation of NdNi 2 alloy.…”

“…The decrease in the Dy/Nd separation ratio was attributed to the effect of the fluoride bath, while the increase in the alloy formation rate was attributed to the high temperature. Recently, we evaluated CaCl 2 as a low-vapor-pressure chloride salt because both a high Dy/Nd separation ratio and high alloy formation rate are expected in a high-temperature operable chloride system. , In our previous studies, the electrochemical formation potentials of Nd–Ni and Dy–Ni alloys were investigated in molten CaCl 2 –NdCl 3 and CaCl 2 –DyCl 3 systems, respectively; DyNi 2 , DyNi 3 , and DyNi 5 alloys have more positive formation potentials than the same types of Nd–Ni alloys, NdNi 2 , NdNi 3 , and NdNi 5 , respectively.…”

“…Electrochemical Formation Reactions and Corresponding Two-Phase Coexisting Potentials of RE−Ni (RE = Nd and Dy) Alloys in Molten CaCl 2 −RECl 3 (1.0 mol %) at 1123 K23,24 …”

A Combinatorial Electrode for High‐Throughput, High‐Entropy Alloy Screening

“…In addition, the electrolytic HEAs can be controlled by controlling the component of oxide precursors. However, the current molten salt electrolysis only produces one sample for each electrolysis, [26–28] which remains a low‐efficient way. According to the characteristics of the electro‐metallization of solid oxides in molten salt, a combinatorial electrode was designed to increase the efficiency of the electrolysis.…”

Electrochemical CaC2‐Mediated Conversion of Biochar to C2H2: High Carbon Efficiency and Low Contamination

“…This was also confirmed by GC-MS (mass spectrum) analysis (Figure S6), proving the generation of CaC 2 by the solid cathode electrolysis. A small chromatographic peak of H 2 was also found (the H 2 to C 2 H 2 ratio was measured to be about 0.005, see Supporting Information the chapter "Analysis of the hydrolysis C 2 H 2 product" and Figure S7); this is likely because that CaÀ Ni alloys formed on the Ni foam during the electrolysis (Figure S8), [11] which can react with water to release H 2 .…”