Activation energy and saddle point configuration of high-mobility dislocation loops: A line tension model

Kazuhito Ohsawa, E. Kuramoto

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We report an analytical study of thermally activated motion of perfect dislocation loops with high mobility in terms of an elastic model, where the dislocation loops are assumed to be smooth flexible strings under the influence of a potential barrier. The activation energy and saddle point configuration of the dislocation loops are analytically expressed within the present model. The activation energy monotonously increases with the loop length and converges to a finite value. However, the features of the thermally activated motion remarkably change depending on the loop length. If the dislocation loops are longer than a critical length Lc, the saddle point configuration is the well-known double-kink type. On the other hand, if the dislocation loops are shorter than Lc, the saddle point configuration is the so-called rigid type, that is, the dislocation loops overcome the potential barrier without changing their shapes except for thermal fluctuations. The former is regarded as dislocation-like transport, while the latter is point-defect-like migration. Therefore, as the dislocation loops grow, a transition from point defect to dislocation substantially occurs for the dislocation loops.

Original languageEnglish
Article number054105
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume72
Issue number5
DOIs
Publication statusPublished - Dec 1 2005

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saddle points
Dislocations (crystals)
Activation energy
activation energy
Point defects
configurations
point defects
strings

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

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abstract = "We report an analytical study of thermally activated motion of perfect dislocation loops with high mobility in terms of an elastic model, where the dislocation loops are assumed to be smooth flexible strings under the influence of a potential barrier. The activation energy and saddle point configuration of the dislocation loops are analytically expressed within the present model. The activation energy monotonously increases with the loop length and converges to a finite value. However, the features of the thermally activated motion remarkably change depending on the loop length. If the dislocation loops are longer than a critical length Lc, the saddle point configuration is the well-known double-kink type. On the other hand, if the dislocation loops are shorter than Lc, the saddle point configuration is the so-called rigid type, that is, the dislocation loops overcome the potential barrier without changing their shapes except for thermal fluctuations. The former is regarded as dislocation-like transport, while the latter is point-defect-like migration. Therefore, as the dislocation loops grow, a transition from point defect to dislocation substantially occurs for the dislocation loops.",
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AU - Kuramoto, E.

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N2 - We report an analytical study of thermally activated motion of perfect dislocation loops with high mobility in terms of an elastic model, where the dislocation loops are assumed to be smooth flexible strings under the influence of a potential barrier. The activation energy and saddle point configuration of the dislocation loops are analytically expressed within the present model. The activation energy monotonously increases with the loop length and converges to a finite value. However, the features of the thermally activated motion remarkably change depending on the loop length. If the dislocation loops are longer than a critical length Lc, the saddle point configuration is the well-known double-kink type. On the other hand, if the dislocation loops are shorter than Lc, the saddle point configuration is the so-called rigid type, that is, the dislocation loops overcome the potential barrier without changing their shapes except for thermal fluctuations. The former is regarded as dislocation-like transport, while the latter is point-defect-like migration. Therefore, as the dislocation loops grow, a transition from point defect to dislocation substantially occurs for the dislocation loops.

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