An investigation was made of the self-diffusion of 36Cl in single crystals of various purity. They were of high purity, or were doped with 27, 65 or 363 ions of Sr2+ per 106 ions of Na+ (figure 25). Transport in the high-purity material was characterized by intrinsic behavior, while that in strongly-doped material was characterized by extrinsic behavior. At temperatures ranging from 520 to 740C, the diffusion data in intrinsic samples of pure material could be described by:

D (cm2/s) = 61 exp[-2.14(eV)/kT]

Within the same temperature range, the diffusion data in extrinsic samples of doped (363 ions of Sr2+ per 106 ions of Na+) material could be described by:

D (cm2/s) = 1.4 x 104 exp[-2.69(eV)/kT]

The samples which were doped to intermediate levels behaved extrinsically at lower temperatures and intrinsically at higher temperatures.

Self-Diffusion of Cl Ions in Sr2+-Doped NaCl Crystals. F.Bénière, M.Bénière, M.Chemla: Comptes Rendus de l’Academie des Sciences – C, 1968, 267[10], 633-6

Table 121

Diffusivity of 36Cl in NaCl Melts