An analytical study of the thermally activated motion of perfect dislocation loops with high mobility, in terms of an elastic model, was reported. The dislocation loops were assumed to be smooth flexible strings under the influence of a potential barrier. The activation energy and saddle-point configuration of the dislocation loops were analytically expressed within the present model. The activation energy increased monotonically with loop length, and converged to a finite value. However, the features of thermally activated motion changed markedly; depending upon the loop length. If the dislocation loops were longer than a critical length, Lc, the saddle-point configuration was the well-known double-kink type. If the dislocation loops were shorter than Lc, the saddle-point configuration was the so-called rigid type. That is, the dislocation loops

overcame the potential barrier without changing their shapes; except for thermal fluctuations. The former was regarded as being dislocation-like transport, while the latter was point-defect like migration. Thus, as the dislocation loops grew, a transition from point defect to dislocation occurred for the dislocation loops.

Activation Energy and Saddle-Point Configuration of High-Mobility Dislocation Loops - a Line Tension Model. K.Ohsawa, E.Kuramoto: Physical Review B, 2005, 72[5], 054105 (7pp)