Electrochemical behavior and underpotential deposition of Sm on reactive electrodes (Al, Ni, Cu and Zn) in a LiCl-KCl melt

Sm extraction from a LiCl-KCl melt was carried out by forming alloys on various electrodes, including Al, Ni, Cu, and liquid Zn, and the electrochemical behaviors of the resultant metal products were investigated using different electrochemical techniques. While Sm metal deposition via the conventional two-step reaction process was not noted on the inert electrode, underpotential deposition was observed on the reactive electrodes because of the latter’s depolarization effect. The depolarization effects of the reactive electrodes on Sm showed the order Zn > Al > Ni > Cu. Sm-M (M = Al, Ni, Cu, Zn) alloys were deposited by galvanostatic and potentiostatic electrolysis. The products were fully characterized by X-ray diffractometry (XRD) and scanning electron microscopy (SEM)-energy dispersive spectrometry (EDS), and the stability of the obtained M-rich compounds was determined. Finally, the relationship between the electrode potential and type of Sm-M intermetallic compounds formed was assessed on the basis of the observed electrochemical properties and electrodeposits.