Investigation into cathodic reduction process of Yb(III) ion in (LiF-YbF3)eut.-Yb2O3 molten salt system

Abstract

• The electrochemical behavior of Yb (III) and Yb (Ⅱ) was determined by using different electrodes (W or Ni) in (LiF-YbF 3 ) eut. and (LiF-YbF 3 ) eut. -Yb 2 O 3 system. • The Ni 2 Yb alloy can be prepared by using the molten salt electrolysis in (LiF-YbF 3 ) eut. -Yb 2 O 3 system on the Ni electrode. • The crystallization process on the surface of W and Ni electrode were determined by chronoamperometry analysis of (LiF-YbF 3 ) eut. -Yb 2 O 3 system. The electrochemical behavior of Yb 3+ ions is investigated through cyclic voltammetry and chronoamperometry/potentiometric methods on the surface of a W/Ni working electrode in a (LiF-YbF 3 ) eut -Yb 2 O 3 molten salt system. The results show that the reduction of Yb 3+ ions is completed by two-step quasi-reversible processes of Yb 3+ /Yb 2+ and Yb 2+ /Yb on the W and Ni cathodes in LiF-YbF 3 and (LiF-YbF 3 ) eut -Yb 2 O 3 molten salt systems at 1223K; and the diffusion coefficients of Yb 3+ are 5.45×10 -4 cm 2 ·s -1 and 3.75×10 -3 cm 2 ·s -1 , respectively. The addition of Yb 2 O 3 can improve the electrochemical activity of Yb 3+ in the LiF-YbF 3 system. The crystallization of Yb 3+ ions are through three-dimensional instantaneous and continuous nucleation on the W and Ni electrodes in the (LiF-YbF 3 ) eut -Yb 2 O 3 molten salt system, respectively. The reduction activity of Yb 2+ ions on the Ni cathode is stronger than on the W cathode, which is beneficial to alloying. The Ni 2 Yb alloy can be prepared by constant voltage electrolysis with Ni as a consumable cathode in the (LiF-YbF 3 ) eut -Yb 2 O 3 molten salt system.