Characterization of Ce-Bi intermetallic compound formations by electrolytic reduction in molten LiCl-KCl eutectic

Abstract

The intermetallic compound formations of Ce-Bi on an inert W electrode in the molten LiCl-KCl eutectic with CeCl3 and BiCl3 for an electrolytic reduction process was investigated with various electrochemical techniques of cyclic voltammetry, square wave voltammetry, and open circuit chronopotentiometry. The electrochemical reduction of Ce3+ on the inert electrode at 773 K was observed at more positive potential with Bi3+ than that without Bi3+ due to lowering activity of Ce by intermetallic compound formations. Cyclic voltammogram and square wave voltammogram exhibited four reduction peaks with overlapping signals. Application of peak separation technique allow five intermetallic compounds of BiCe1/2, BiCe, BiCe4/3, BiCe5/3, BiCe2 to be determined. Intermetallic compound formations of Ce-Bi were confirmed with open circuit chronopotentiogram which exhibited five plateau corresponding to a state in which two phases of intermetallic compounds coexist on the electrode surface. Analysis of cyclic voltammograms according to molar ratio of Bi to Ce showed that the amount of CeBi2 and CeBi at the reduction potential above −1.5 V were increased at the higher molar ratio of Bi to Ce. The experimental results indicated that intermetallic compounds of Ce-Bi could be formed on the inert electrode in LiCl-KCl-CeCl3-BiCl3 melt by electrolytic reduction and the type and amount of the resulting intermetallic compound on the inert electrode by electrolytic reduction could be varied depending on the applied potential and molar ratio of Bi to Ce, respectively.