Self-diffusion was measured in SiO2-20K2O-20wt%SrO, above and below the glass transition temperature, by using the reaction, 18O(p,α)15N, to determine concentration profiles. At 600 to 1000K, the diffusion data could be described by:

>Tg:     D (cm2/s) = 7.6 x 1014 exp[-119(kcal/mol)/RT]

<Tg:     D (cm2/s) = 1.0 x 10-12 exp[-10(kcal/mol)/RT]

It was suggested that O diffused as molecules below Tg. A rapid increase in diffusion above Tg was attributed to an excess structural activation energy which was required for the migration of O ions.

B.S.Rawal, A.R.Cooper: Journal of Materials Science, 1979, 14[6], 1425-32