Experiments on this system were reviewed. Most of the diffusion annealing was carried out in sealed silica capsules under saturated Hg vapour pressures, and the concentration profiles were measured by using a sectioning technique. Two-component profiles were usually found. This revealed rate-limiting volume diffusion involving a slow stream (trapped species) and a fast stream (mobile species). On the basis of pressure dependence data, it was proposed that the slow component occurred via an interstitial mechanism at low Hg partial pressures, and via a vacancy mechanism at high partial pressures. The diffusivity of the slow component increased with etch-pit density, while the diffusivity of the fast component was independent of the etch-pit density. The Arrhenius plots exhibited a sharp change in slope at 275C.

E.D.Jones, M.U.Ahmed: Proceedings of the International Society for Optical Engineering, 1997, 3182, 342-58