Evaluation of the thermochemical properties of Ho–Cd intermetallic compounds using electrochemical techniques

Abstract

The electrochemical formation of HoCd₆, HoCd_45/11, HoCd₃, HoCd₂ and HoCd, on a Cd coated tungsten electrode in the eutectic LiCl–KCl has been evaluated in a qualitative and quantitative manner using electrochemical techniques (i.e. cyclic voltammetry, anodic stripping voltammetry and open circuit chronopotentiometry) over the temperature range of 673–823 K. The formation energy of each intermetallic compound, as well as the global formation constants were calculated for the first time. The activities and relative partial molar Gibbs energies of Ho and Cd were also obtained for HoCd₆, HoCd_45/11, HoCd₃, HoCd₂ and HoCd. At the Cd distillation temperature, the molar Gibbs free energy of the intermetallic compounds achieves the minimum value for HoCd₂ and HoCd, suggesting that the dissolution of U or Pu from the U–Pu–Ho–Cd alloy into HoCd₂ and HoCd should be considered.