The self-diffusivity was monitored by means of nuclear magnetic resonance pulsed field gradient techniques at 80 to 200C. The F diffusion coefficient varied from 1.5 x 10-8cm2/s at 80C to 8.5 x 10-7cm2/s at 200C. A phase transition was detected at about 100C.

W.D.Basler, I.V.Murin, S.V.Chernov: Zeitschrift für Naturforschung, 1981, 36a[4], 519-20