Self-Diffusion of Sodium in Sodium Chloride and Sodium Bromide

Abstract

The self-diffusion coefficient of sodium in sodium chloride and sodium bromide has been measured as a function of temperature. A comparison of the self-diffusion coefficient with the electrolytic conductivity reveals that the Einstein relation is satisfied at high but not at low temperatures. The temperature dependence of the diffusion coefficient may be explained by the Schottky-Wagner vacancy theory if the presence of impurity ions is taken into account. A possible explanation for the failure of the Einstein relation in terms of association between multivalent foreign ions and vacancies is suggested.

Ionic Conductivity of NaCl: SrCl2 Crystals

“…Fuller and Reilly,lO utilizing published ionic conductivity and diffusion data, have calculated recently the anion transport number in NaCl at high temperature. They are much higher than the first values reported by Tubandt et al,u and the recent ones by Allnatt and Chadwick 12 after the sodium ion diffusion data of Mapother et al,13 and the chlorine ion diffusion data of Barr et al, 14 We tried, in solving Eq. (9), the same approximation as Brown (I/C:'O in comparison of the values of 0 and a second approach using Fuller's values for the anion transport numbers.…”

Self-Diffusion of the Chloride Ion in Sodium Chloride

“…Corrections to the data were made for the effect of the finite slice thickness, finite initial layer size, and for any misalignment. 16 The diffusion coefficient was calculated by making a least squares fit of the data to a Gaussian penetration curve. The temperature of the crystals during the diffusion anneal was measured by a platinum-platinum 10% rhodium thermocouple placed in thermal contact with the crystal.…”

Measurements of Self-Diffusion in Aqueous Solutions of Sodium Dihydrogen Phosphate

“…In a study of the diffusion of sodium ion in a sodium chloride crystal, sodium chloride, labeled with NaZ2, was coated onto one face of a sodium chloride crystal. After allowing the NaZZC1 to penetrate for a suitable time, the crystal was pared down, slice a t a time, and the activity of successive slices measured (11). The self-diffusion coefficients of various ions in solution have also been determined, and, in several instances, comparisons made with the values predicted from the theories of Nernst and Onsager.…”