Electrochemical Formation of Ce-Ni Alloys and Separation of Ce in Molten LiCl-KCl Systems

Abstract

The electrochemical formation of Ce-Ni alloys was investigated in a molten LiCl-KCl-CeCl₃ at 723 K under an Ar gas atmosphere. Open-circuit potentiometry was performed with a Ni electrode after electrodepositing Ce metal at 0.40 V (vs. Li⁺/Li) for 20 s. Four potential plateaus were observed at 0.54 V, 0.72 V, 1.19 V and 1.64 V, which were considered to correspond to the potentials of two-phase coexisting states of different Ce–Ni alloys. Potentiostatic electrolysis was conducted at 0.50 V for 1 h using Ni plate electrodes, and XRD analysis indicated the formation of CeNi₂. After the formation of CeNi₂ on the Ni plate electrodes, potentiostatic electrolysis was also conducted at 0.65 V, 0.80 V, 1.40 V and 2.00 V for 1 h. The formed CeNi₂ was transformed to CeNi₃ at 0.65 V, Ce₂Ni₇ at 0.80 V, CeNi₅ at 1.40 V and Ni at 2.00 V. On the other hand, an alloy sample was prepared at 0.50-0.60 V for 1 h using a Ni electrode in molten LiCl-KCl-CeCl₃(0.50 mol%)-LaCl₃(0.50 mol%). The highest mass ratio of Ce/La in the alloy samples was 84 at 0.51-0.53 V.