Cyclic Voltammetry Behavior of Americium at a Liquid Cadmium Electrode in LiCl-KCl Eutectic Melts

The electrode reactions of americium at a liquid cadmium electrode were investigated by cyclic voltammetry of AmCl₃-(LiCl-KCl)_eut. at both 723 and 773 K in comparison with those at a molybdenum electrode. The redox peaks assigned to Am(III)/Am(0) (in Cd) were observed with the liquid Cd electrode, while the redox reactions of Am(III)/Am(II) and Am(II)/Am(0) were observed with the Mo electrode. The formal standard potential of Am(III)/Am(0) obtained with the liquid Cd electrode is more positive than those calculated for the Mo electrode at both 723 and 773 K. The potential shifts were attributed to the lowering of the activity of Am by the formation of the intermetallic compound at the interface between Cd and the molten salt. The Gibbs free energies of formation of the Am-Cd intermetallic compound, which could be AmCd₆, are estimated to be -119 and -113 kJ/mol at 723 and 773 K, respectively.