Quantitative Description of the Equilibrium Potentials and Atomic Radius of the Co-Ln Alloy by a Mathematical Equation

The intermetallic compound formations of Co-Ln (Ce, Pr, Gd, Dy and Er) in the molten LiCl-KCl eutectic at 873 K for an electrolytic reduction process was investigated with various electrochemical techniques of cyclic voltammetry, square wave voltammetry and open-circuit chronopotentiometry. The deposited Co-Ln alloy samples were prepared by potentiostatic electrolysis and further characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). A mathematical model about the equilibrium potentials of Co-Ln intermetallic compounds and atomic radius was proposed in this work. The fitted equation is Y = 0.1402X − 0.6457 (R2 = 0.992). Because of the close similarity of chemical properties, the equilibrium potentials of Co-An intermetallic compounds can be simulated and predicted through the mathematical equation. In addition, the relationship between the equilibrium potentials and atomic radius of Ni-Ln and Cu-Ln alloy compounds were also in accordance with the mathematical model, while show a good linear relationship. The work described here can broaden the applications of mathematical model and highlight its potentials in future molten salt electrolysis based spent fuel pyroprocessing.