A capillary reservoir technique was used to investigate the diffusion of 18F in molten mixtures (table 202). A relatively high diffusivity of 18F contrasted with a rather low mobility of F which was due to the presence of an external electric field. These results were thought to indicate that F was present not only as AlF63- and AlF4- ions, but also had to be present in the form of small neutral or positive groups in molten cryolite.
F.Lantelme, M.Chemla: Comptes Rendus de l’Academie des Sciences – C, 1968, 262, 281-4
Table 202
Self-Diffusion of 18F in Molten Na3AlF6-Al2O3 Mixtures
Al2O3 (%) | Temperature (C) | D (cm2/s) |
0 | 1034.0 | 5.70 x 10-5 |
0 | 1045.5 | 5.86 x 10-5 |
0 | 1052.0 | 5.81 x 10-5 |
0 | 1065.0 | 6.10 x 10-5 |
12.9 | 1052.5 | 3.81 x 10-5 |