Serial sectioning techniques were used to obtain 65Zn tracer diffusion data for high-purity single crystals (table 45). It was shown that the diffusion of Zn2+ tracer proceeded substitutionally at 209 to 441C. Any contribution from an interstitial mechanism was masked by an extraordinarily large substitutional component. This very large substitutional diffusivity was attributed to an unusually high solute ion-vacancy binding energy; perhaps of the order of 0.6eV. As a consequence, the diffusion activation energy was only 0.77eV. That is, for temperatures of 209 to 350C:
D (cm2/s) = 0.053 exp[-0.77(eV)/kT]
The data for temperatures of 352 to 441C were described by:
D (cm2/s) = 4.5 exp[-1.01(eV)/kT]
Diffusion of Zinc Tracer in Silver Chloride. A.P.Batra, L.M.Slifkin: Physica Status Solidi A, 1973, 19[1], 171-7
Table 46
Diffusivity of Cd2+ in AgCl-CdCl2 Crystals
CdCl2 (mol%) | Temperature (C) | D (cm2/s) |
0.9 | 150 | 7.8 x 10-11 |
2.8 | 150 | 2.0 x 10-10 |
0.9 | 200 | 3.7 x 10-10 |
2.8 | 200 | 1.3 x 10-9 |
0.9 | 250 | 1.4 x 10-9 |
2.8 | 250 | 5.9 x 10-9 |
0.9 | 300 | 2.4 x 10-9 |
2.8 | 300 | 9.5 x 10-9 |
0.9 | 350 | 3.6 x 10-9 |
2.8 | 350 | 1.8 x 10-8 |
2.8 | 400 | 2.6 x 10-8 |