The capillary reservoir technique was used to study the diffusion of 18F in molten mixtures (table 208). It was suggested that AlF63-, AlF4-, NaF and Na2F+ complexes were present in the melt. The activation energy for 18F diffusion in samples with 13.5mol%AlF3, at temperatures ranging from 938 to 1070C, was 12.5kcal/mol. The activation energy for diffusion in samples with 37.5mol%AlF3, at temperatures ranging from 928 to 999.7C, was 7.0kcal/mol.
D.Harari, F.Lantelme, M.Chemla: Journal de Chimie Physique et de Physicochimie Biologique, 1969, 66[7-8], 1286-91
Table 208
Self-Diffusion of 18F in NaF-AlF3 Melts
AlF3 (mol%) | Temperature (C) | D (cm2/s) |
0 | 1049 | 9.67 x 10-5 |
0 | 1052 | 9.15 x 10-5 |
13.5 | 938 | 4.5 x 10-5 |
13.5 | 1012 | 5.72 x 10-5 |
13.5 | 1051 | 7.59 x 10-5 |
25.0 | 1048 | 5.65 x 10-5 |
25.0 | 1049.5 | 5.77 x 10-5 |
37.5 | 928 | 5.50 x 10-5 |
37.5 | 941 | 5.43 x 10-5 |
37.5 | 968.5 | 5.74 x 10-5 |
37.5 | 999.7 | 6.31 x 10-5 |