The relaxation of stress-induced dichroism of the 0.009mm band was measured in order to determine the O diffusion coefficient at between 250 and 400C. Enhanced diffusion, with an activation energy of 1.85eV, occurred as a transient behavior in certain samples and was attributed to O-vacancy interactions. It was shown that A-centers, [O-V], annealed in two stages. The first involved an activation energy of 1.8eV. There was no evidence for an enhanced rate of long-range mass transport.

A.K.Tipping, R.C.Newman, D.C.Newton, J.H.Tucker: Materials Science Forum, 1986, 10-12, 887-92