Study on the Determination of Conductivity of Molten Salt System of Sm<sub>2</sub>Fe<sub>17</sub> Alloy Electrolysis by AC Impedance

The preparation process of single-phase Sm₂Fe₁₇ alloy is directly influenced by the conductivity change of the CaCl₂-CaF₂-SmCl₃ molten salt system. In this study, AC impedance was employed to systematically investigate the influencing factors and variation patterns of the conductivity in CaCl₂, CaCl₂-CaF₂, and CaCl₂-CaF₂-SmCl₃ molten salt systems. It was observed that as the temperature and SmCl₃ content increased in the molten salt, the impedance value decreased while electrical conductivity increased. The conductivity range of the molten salt was determined to be 0.441 S/cm~0.672 S/cm. Additionally, with an increase in SmCl₃ content within the molten salt, its activation energy for conductivity decreased accordingly. By fitting the data on molten salt’s conductivity, a functional relationship between temperature and SmCl₃ content (ranging from 0 to 5%, mole fraction) in a CaCl₂-CaF₂ mole ratio of 1∶1 at temperatures ranging from 1173 K to 1373 K was established; these findings provide a theoretical foundation for electrochemical synthesis of single-phase Sm₂Fe₁₇ alloy.