Electrochemical co-reduction of holmium and magnesium ions in eutectic LiCl–KCl salts

Abstract

The electrochemical co-reduction of Ho(III) and Mg(II) ions was investigated on Mo electrode in eutectic LiCl–KCl salts at temperature of 773 K using various electrochemical techniques. Cyclic voltammogram (CV) and square wave voltammogram exhibit three reduction peaks corresponding to the reduction of Ho(III) on pre-deposited Mg electrode, whose potentials are more positive than that of Ho on Mo electrode because of the formation of Mg-Ho intermetallic compounds by co-reduction of Ho(III) and Mg(II) ions. Meanwhile, chronopotentiometry and open-circuit chronopotentiometry were used to explore the electrochemical formation of Mg–Ho intermetallics. Mg–Ho alloys were produced by galvanostatic electrolysis at the current of 1.5 A for different electrolysis durations. Ho5Mg24, HoMg2 and HoMg intermetallic compounds were acquired and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS). The results indicate that Mg–Ho intermetallic compounds, Ho5Mg24, HoMg2 and HoMg, could be prepared by molten salts electrolysis.