Electrochemical behavior of praseodymium and Pr-Al intermetallics in LiCl-KCl-AlCl3-PrCl3 melts

The electrochemical behavior of Pr(III) and formation process of Pr-Al intermetallics were investigated by different electrochemical methods. The reduction of Pr(III) ion to metallic Pr is an one-step three-electrons reaction. The reversibility of Pr(III)/Pr(0) system was evaluated by cyclic voltammograms with different scan rates. The co-reduction of Pr(III) and Al(III) ions formed three different Pr-Al intermetallics at electrode potentials around −1.40, −1.80, and −1.95 V vs. Ag/AgCl at 723 K, respectively. Open-circuit chronopotentiometry and electromotive force (emf) measurements were carried out to estimate the relative molar Gibbs energies of Pr for the formation of different Pr-Al intermetallics in the temperature range of 723–843 K. The activities of Pr in the Pr-Al intermetallic compounds were calculated.