The diffusion of 41Ar and 39Ar in single crystals was investigated, after neutron irradiation, by collecting the released Ar in a liquid-N trap (tables 73 and 74). There appeared to be a relationship between the activation energy and the energy barrier for interstitial diffusion. Low diffusivities were found not only after increased neutron doses but also after doping with SrCl2. It was assumed that the trapping of rare gas occurred, and that vacancy clusters acted as trapping centers. The damaged lattice partially recovered during annealing, but numerous clusters remained after prolonged heat treatment at 650C.

P.Schmeling: Journal of the Physics and Chemistry of Solids, 1967, 28, 1185-96

 

Table 73

Diffusion of Ar in Single Crystals of KCl

(doped with 0.02mol%K2S and irradiated to a dose of 9 x 1013/cm2)

 

Temperature (C)

D (cm2/s)

285

1.00 x 10-11

358

1.18 x 10-7

385

1.48 x 10-7

451

2.14 x 10-6

558

3.31 x 10-6

644

7.94 x 10-6

697

5.89 x 10-6

 

 

Table 74

Diffusion of 39Ar in Single Crystals of KCl after Neutron Irradiation

 

Dose (/cm2)

Temperature (C)

D (cm2/s)

1.0 x 1018

500

4.6 x 10-7

1.0 x 1018

600

2.2 x 10-6

1.2 x 1018

428

3.6 x 10-9