By using the serial sectioning technique, a study was made of the effect of a Cl2 pressure upon the diffusion of 198Au in single crystals. When diffusion annealing was carried out in a mixture of 1torr Cl2 and 400torr He, the (presumably) intrinsic Au diffusivity could be described, at temperatures ranging from 260 to 440C, by:

D (cm2/s) = 5.0 x 10-3 exp[-0.47(eV)/kT]

This indicated an interstitial diffusion mechanism. When diffusion annealing was carried out in an 0.7atmCl2 atmosphere, the Au diffusivity was depressed and the Arrhenius plot consisted of 2 approximately linear segments; with a break at about 300C. At temperatures ranging from 260 to 300C, the Au diffusivity could be described by:

D (cm2/s) = 14 exp[-0.87(eV)/kT]

Increasing the Cl2 pressure, to 2atm., depressed the Au diffusivity somewhat more and the break in the 2 linear segments of the Arrhenius plot shifted to 340C. The observed behavior was explained in terms of the effect of Cl upon the cation vacancy concentration.

Low Temperature Suppression by Chlorine of Diffusion of Gold in Silver Chloride. A.P.Batra, A.L.Laskar, L.Slifkin: Journal of Physics and Chemistry of Solids, 1969, 30[8], 2053-9

Table 28

Self-Diffusion of 110mAg in AgCl

at Room Temperature