Extraction of europium and electrodeposition of Al-Li-Eu alloy from Eu_2O_3 assisted by AlCl_3 in LiCl-KCl melt

摘要

The work presents an electrochemical study on preparation of Al-Li-Eu alloys on a tungsten electrode in molten LiCl-KCl-AlCl_3-Eu_2O_3 system at 753 K and 953 K. Gibbs energy shows that AlCl_3 can chloridize Eu_2O_3, with a discharge in the form of Eu(III) ions on the cathode. The electrochemical behavior of Al(III), Li(I) and Eu(III) and alloy formation processes were investigated by cyclic voltammetry, square wave voltammetry, and chronopotentiometry. Cyclic voltammetry indicated that the underpotential deposition of europium on pre-deposited Al forms two Al-Eu intermetallic compounds at electrode potentials around -2.00 V and -2.34 V, respectively. And the underpotential deposition of lithium on Al surface at about -2.24 V leads to a formation of Al-Li alloy. X-ray diffraction (XRD) indicated that Al-Li-Eu alloys with different phases were obtained via galvanostatic electrolysis. The microstructure and micro-zone chemical analysis of Al-Li-Eu alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively. The analysis of EDS showed that element Eu mainly distributes on needle-like precipitate, and not homogeneously in the Al-Li-Eu alloy. Composition of the alloys was analyzed by inductive coupled plasma analysis, and current efficiency was also determined with respect to the alloy composition.