Density and ionic structure of NdF3-LiF melts

NdF3-LiF melts are commonly used in the electrolysis process of metallic neodymium production. Research on the density and ionic structure of the electrolyte is important for its close connection with the electrolysis mechanism and process. In this paper, the density of LiF-NdF3 melts was studied by the Archimedes method. The results showed that the density decreased with increasing temperature and LiF contents. The changing law was discussed and explained in terms of the micro ionic structure of the melts. The ionic structure of 25 mol.% NdF3–75 mol.%LiF was then quantitatively analyzed on the condition that [Nd]3+ existed in the forms of both NdF63− and NdF4−. The results indicated that NdF63−, NdF4−, and F− took the amount of 22 mol.%-25 mol.%, 25 mol.%, and 50 mol.%-52 mol.% respectively in the anions of the melts in the temperature range of 950-1050 °C. In addition, NdF63− was easier to decompose at a higher temperature.