Formation of Ni-Nd alloys by Nd(III) electrochemical reduction in molten fluoride

Abstract

The electrochemical reduction of Nd(III) in molten LiF-CaF2 media was investigated on different electrode materials. First, some experiments have been carried out on inert electrode (Ta) and then on a reactive one (Ni). The reduction of Nd(III) on a nickel electrode was observed to lead to intermetallic compounds formation. Metalliding process was carried out on nickel cathode leading formation of the most stable compound in the binary diagram (NdNi5). Using open-circuit chronopotentiometry and SEM observations, the mechanism of alloys formation and the Gibbs energy of these compounds have been determined for the Nd-Ni system in the 800-950°C range. Finally, reduction of Nd(III) on Cu-Ni electrode has also been studied and the formation of ternary Cu-Ni-Nd alloys , with a high Nd content, was observed.