Probing the ionic structure of FLiNaK-ZrF salt mixtures by solid-state NMR.

In this study, by applying F, Na and Li high-resolution NMR methods, the evolution of the [Zr F ] local ionic structures in FLiNaK-ZrF salt mixtures were elucidated. KZrF, NaZrF and NaZrF crystal phases were identified when the melt salts were being solidified. The distribution of these [Zr F ] species was dependent on the content of ZrF in FLiNaK eutectic salts. Moreover, KZrF phase transition from an orthorhombic lattice into a disordered cubic lattice was clarified, thereby causing dynamics of the coordinated F ions to be reduced and the well-ordered crystal lattices to be destroyed. These mentioned results provide a further insight into the Zr-F based ionic structure and the formation of the disordered Zr-F structure in ZrF-based eutectic salts.