Electrochemistry of rare earth fluoride molten salts

Abstract

This study deals with fundamental research on the production of rare earth metals by electrolysis. We use fluoride fused salts and rare earth oxides as raw materials. In the design of our electrolytic cell we have to know the types of electrochemical reaction, the critical current densities and the melting points of the fused salts. We have measured the polarization curves and melting points of the electrolytes and we discuss the electrochemical reactions of rare earth oxides and fluoride fused salts. We have confirmed the reactions of oxygen evolution, fluorine evolution and electrodeposition of rare earth metals or alloys. The anodic critical current density of the cerium molten salt is 9 A cm −2 at 890°C and that of the neodymium molten salt is 1.6 A cm −1 at 920°C.