Electrochemical Synthesis and Thermodynamic Properties of Pr-Ni Intermetallic Compounds in a LiCl-KCl-NiCl2-PrCl3 Melt

In this report, the electrochemical behaviors of Pr(III) and Ni(II) ions on a W electrode were investigated in LiCl-KCl eutectic by cyclic voltammetry (CV), square wave voltammetry (SWV), chronopotentiometry (CP) and open-circuit chronopotentiometry (OCP) techniques. From the results of electrochemical methods, different signals corresponding to seven kinds of intermetallic compounds in the phase diagram of Pr-Ni were observed. The thermodynamic properties of intermetallic compounds in the temperature range of 823-923 K were investigated by open-circuit chronopotentiometry. With the evaluated apparent standard potentials of Pr-Ni intermetallic compounds, the Gibbs energies, enthalpies and entropies of formation were also calculated. The co-reduction products by galvanostatic and potentiostatic electrolysis were characterized based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The shape of the alloy obviously changes from granular to bulk, and the alloy phase changes from Pr-rich to Ni-rich. The co-reduction products of PrNi5, PrNi2 and PrNi were identified.