Preparation and characterization of Sm2Fe17 alloy in LiF-CaF2-SmF3 molten salt

A suitable temperature range of Sm2Fe17 alloy formed only was chosen to investigate the electroreduction of Sm3+ on molybdenum and iron electrode in LiF-CaF2-SmF3 molten salt, which were studied by CV and SWV at different temperatures and concentrations of Sm3+. The reduction of Sm3+ to Sm0 on the iron electrode included two steps. Firstly, a soluble-soluble reaction appears at −0.33 V vs. Cr/Cr2O3 corresponds to the electroreduction of Sm3+ to Sm2+. The electroreduction of Sm3+ to Sm2+ is a reversible process, which is controlled by the diffusion of Sm3+ in the LiF-CaF2-SmF3 molten salt. Secondly, Sm2+ can be reduced at −0.78 V vs. Cr/Cr2O3 on the iron electrode in LiF-CaF2-SmF3 molten salt due to a lower activity of metallic samarium in the Sm2Fe17 alloy than that of samarium metal, and that makes samarium in Sm-Fe alloy more stable while that of Sm2+ could be not reduced by a molybdenum electrode. By experiment of potentiostatic electrolysis it was confirmed that the cathode product from LiF-CaF2-SmF3 melts at −1 V vs. Cr/Cr2O3 for 4 h is a thin layer metallic plate only composing Sm2Fe17 alloy.