By using the serial sectioning technique, a study was made of the self-diffusion of 22Na and 24Na in CaCl2- or CdCl2-doped material. When combined with ionic conductivity measurements, the results indicated that the heats of association of the divalent additions to complexes with cation vacancies were very similar (0.28eV). The Stasiw-Teltow association model was applicable, at Ca concentrations which did not exceed 0.1mol%, for temperatures ranging from 150 to 720C. This model yielded a value of 0.284eV for the enthalpy of association of Ca2+ complexes, a value of 0.74eV for the migration enthalpy of free vacancies, and a negligibly low entropy of association of the complexes.

Ionic Conductivity and Cation Self-Diffusion in Sodium Chloride Crystals Doped with Calcium or Cadmium. V.Trnovcová: Czechoslovak Journal of Physics, 1969, B19[5], 663-76

 

Table 130

Diffusivity of Na in NaCl

 

Temperature (C)

D (cm2/s)

796.6

1.97 x 10-8

767.1

9.85 x 10-9

751.2

5.83 x 10-9

719.7

3.33 x 10-9

718.8

3.49 x 10-9

683.8

1.25 x 10-9

648.1

4.36 x 10-10

633.7

3.32 x 10-10

627.4

2.90 x 10-10

621.6

1.93 x 10-10

603.8

1.37 x 10-10

602.7

1.39 x 10-10

589.3

8.75 x 10-11

587.4

8.50 x 10-11