Transport Properties in Cryolitic Melts: NMR Measurements and Molecular Dynamics Calculations of Self-Diffusion Coefficients

摘要

Thanks to the development of a new setup based on Pulsed Field Gradient NMR combined with laser heating, we have studied the dynamics of the different nuclei involved in NaF-AlF_3 and LiFA1F_3 cryolitic melts (~(27)A1, ~(23)Na, ~7Li and ~(19)F). The self-diffusion coefficients measured in both systems depending on the composition allow a more precise description of the structure and of the nature of the anionic complexes. For LiF-AlF3, these experiments were combined with molecular dynamics simulations. NMR experiments and MD simulations are in good agreement especially concerning the activation energy of diffusion. Such approach is of primary importance for a better understanding of the physico-chemical properties of the cryolitic melts used in aluminum electrolysis.