The self-diffusion of 19F- was investigated, at temperatures up to the melting point, by using nuclear magnetic resonance techniques. Relaxation-time measurements were performed at 300 to 1095K. An anomalous behavior above 500K was attributed to paramagnetic impurities which were produced as a result of the high reactivity of the fluoride at these temperatures. Direct F- diffusion measurements were made by using nuclear magnetic resonance spin echoes from 570 to 1005K. The formation enthalpy of anion Frenkel pairs was estimated to be 0.88eV; assuming a vacancy mechanism for self-diffusion. Above the phase transition, at 705K, the diffusion coefficient changed more slowly with temperature and was characterized by an activation energy of 0.20eV.

R.E.Gordon, J.H.Strange: Journal of Physics - C, 1978, 11[15], 3213-24