Electrochemically produced divalent neodymium in chloride melt

Production of Nd2+ by cathodic electrolysis of NdCl3 dissolved in molten LiCl–KCl was tested at 773 K. Cyclic voltammetry and differential pulse voltammetry were adopted for the determination of the formal redox potential between Nd3+ and its divalent or metallic states. UV–visible absorption spectrophotometry was carried out at the vicinity of the cathode during the simultaneous electrolysis at −1.9 V versus Ag/Ag+. During the electrolysis, growth of a new broad absorption band ranging from 450 to 580 nm was observed and this was attributed to the absorption by the chloride complex of Nd2+ formed by the electrochemical reduction of NdCl3. Black precipitate formed in the melt as a result of the constant potential electrolysis over long-period was analyzed by EPMA and ICP-AES and they were confirmed to be fine particles of Nd. The results were discussed in relation to the disproportionation of Nd2+ and reaction with quartz vessel.