Electrochemical behavior of neodymium compounds in molten chlorides

Abstract This work presents the electrochemical study of NdCl 3 solutions in fused low-melting LiCl–KCl–CsCl eutectic and individual CsCl at the temperature range 573–943 K using inert molybdenum electrodes. The mechanism of the electrochemical reduction was investigated by transient electrochemical technique. It has been shown that Nd 3 + ions are reduced to metallic neodymium through two consecutive steps: Nd 3+  + ē → Nd 2 + and Nd 2+  + 2ē → Nd 0 . The chemical stability of Nd 2+ ions in fused chloride melts was studied at different temperatures. It was determined that the compound NdCl 2 is not stable in molten solutions at high temperatures (above 810–840 K). The results of a study of the Nd 3+ /Nd 2+ couple redox potentials vs . Cl − /Cl 2 reference electrode at a wide temperature range in molten LiCl–KCl–CsCl eutectic was carried out by direct potentiometric method. Apparent standard redox potentials of the couple E Nd 3 + /Nd 2 + * were determined. Basic thermodynamic properties of the reaction NdCl 2(l)  + ½Cl 2(g)  ⇔ NdCl 3(l) were calculated.