A capillary reservoir technique was used to investigate diffusion of 18F in melts (table 173). 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 suggested that F was present not only as AlF63- and AlF4- ions, but also had to be present as small neutral or positive groups in molten cryolite.
Study of the Diffusion of Na and F Ions in Na3AlF6 Melts. F.Lantelme, M.Chemla: Comptes Rendus de l’Academie des Sciences – C, 1968, 262, 281-4
Table 174
Self-Diffusion of 22Na in Molten Na3AlF6-Al2O3 Mixtures
Al2O3 (%) | Temperature (C) | D (cm2/s) |
0 | 1034.0 | 8.99 x 10-5 |
0 | 1045.5 | 9.45 x 10-5 |
0 | 1052.0 | 9.28 x 10-5 |
0 | 1052.4 | 9.78 x 10-5 |
0 | 1065.0 | 9.87 x 10-5 |
14.0 | 1045.0 | 7.50 x 10-5 |
12.9 | 1052.5 | 7.73 x 10-5 |
12.0 | 1054.0 | 8.09 x 10-5 |