The diffusion of F was monitored by measuring the T1 and T2 relaxation times of the 19F nuclear magnetic resonance at 200 to 500K, and the pulsed magnetic field gradient behavior at 390 to 480K. At about 423K, a sharp transition to the superionic state occurred (figure 33), and the F diffusivity increased by a factor of 4 upon increasing the temperature by 3K.

W.D.Basler, I.V.Murin, S.V.Chernov: Zeitschrift für Naturforschung A, 1983, 38[5], 593-4

Figure 33

Diffusion of F in Sn2KF5