Electrochemical Behavior of Dy(III) and Formation of Dy-Zn Alloy by Co-Reduction with Zn(II) in Eutectic NaCl-KCl Melts

Zengli Zhu, Xiaobin Wu, Zhongsheng Hua, Liang Xu, Shiwei He, Ao Geng, Yongxiang Yang, Zhuo Zhao

Research output: Contribution to journalArticleScientificpeer-review

Abstract

The electrochemical behavior of Dy(III) and its co-reduction process with Zn(II) on a tungsten electrode were studied in eutectic NaCl-KCl melts at 700 °C by using a series of electrochemical techniques. The results indicate that the reduction of Dy(III) to Dy(0) is a diffusion controlled quasi-reversible process through a one-step reaction of exchanging three electrons. The diffusion coefficient of Dy(III) was calculated to be 1.7 × 10-5 cm2 s-1. Furthermore, the co-reduction of Dy(III) and Zn(II) on the tungsten electrode makes Dy(III) be reduced at more positive potentials due to the formation of various Dy-Zn intermetallic compounds. The electromotive force measurements were performed to determine the thermodynamic properties of the Dy-Zn intermetallic compounds, including the activities and relative partial molar Gibbs free energies of dysprosium in the two-phase coexisting state, as well as the standard formation Gibbs energies of Dy-Zn intermetallic compounds. Finally, potentiostatic electrolysis at -2.0 V was carried out in molten NaCl-KCl-DyCl3(1.0 mol%)-ZnCl2(1.0 mol%) at 700 °C for 11 h to prepare Dy-Zn alloy. X-ray diffraction and scan electron micrograph - energy dispersive spectrometry analyses showed that the obtained Dy-Zn alloy mainly comprised of DyZn2, as well as the minor phases of Dy2Zn17, DyZn3 and DyZn.

Original languageEnglish
Article number122509
Number of pages9
JournalJournal of the Electrochemical Society
Volume167
Issue number12
DOIs
Publication statusPublished - 2020

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