The serial sectioning technique was used to investigate Na self-diffusion in single crystals having various degrees of purity. Three materials were used: high-purity, somewhat less-pure and NaCl doped with 2.65 x 10-5Sr2+ ions per Na+ ion. The Na self-diffusion data for pure material in the intrinsic region were the same for high-purity and somewhat less-pure single crystals. The data for 600 to 726C could be described by:

D (cm2/s) = 2.9 x 101 exp[-1.97(eV)/kT]

The data for high-purity single crystals at 390 to 550C could be described by:

D (cm2/s) = 1.6 x 10-3 exp[-1.25(eV)/kT]

The data for less-pure single crystals at 387 to 550C could be described by:

D (cm2/s) = 6.0 x 10-5 exp[-0.98(eV)/kT]

Diffusion data were also presented for the diffusion of Na in Sr-doped single crystals. The data for Sr-doped single crystals at 448 to 588C could be described by:

D (cm2/s) = 6.5 x 10-5 exp[-0.89(eV)/kT]

F.Bénière, F.Chemla: Comptes Rendus de l’Academie des Sciences, 1968, 266[10], 660-3