The role of rapidly diffusing dimers in oxygen loss and the association of thermal donors with small oxygen clusters

The loss of interstitial oxygen from solution is shown to exhibit second order kinetics provided dimer dissociation is not significant at the anneal temperature. Measured changes in the kinetics of the process for anneals at T ⩾ 450 °C can be explained by the increasing effect of this dissociation provided dimers diffuse much more rapidly than isolated atoms and are trapped efficiently. The magnitude of the changes indicates that weakly bound clusters are responsible for this trapping. The formation of two separate series of oxygen clusters containing odd and even numbers of oxygen atoms would be a consequence of clustering by dimer addition. The assignment of thermal donors to the odd-numbered series is suggested.