[en] In this work the dynamics of fluorine in solid-state electrolytes having BaF₂-structure was investigated using three different NMR-methods: field cycling relaxometry, lineshape analysis, and static field gradient NMR. For this purpose a pure BaF₂ crystal, as well as crystals doped with trivalent impurities (LaF₃), were studied as a function of temperature. Using MAS NMR it was possible to identify two lines in Ba_0.9La_0.1F_2.1 having different chemical shift, and to refer them to the modified crystal structure. On this basis a model for the fluorine lineshape has been developed, taking into account three motional processes characterized by their correlation times. It includes jump diffusion of the fluorine ions among equivalent sites within two crystallographically distinct sublattices, and inter-lattice exchange processes. By measuring frequency and temperature-dependent spin lattice relaxation times, it was possible to gain information about fluorine dynamics on microscopic length scales. An attempt was also made to analyze the data for pure BaF₂ and low admixture concentration samples with a non-exponential correlation function. (orig.)