Simulation of screw dislocations in wadsleyite

AM Walker

Research output: Contribution to journalArticle (Academic Journal)peer-review

10 Citations (Scopus)

Abstract

The structure and energies of the cores of [100] and [001] screw dislocations in wadsleyite (β-Mg2SiO4) are calculated using a cluster-based combined elastic-atomistic method and a new parameterized interatomic potential model. For a core radius of 10 Å, core energies are found to be 2.5 and 4.4 eV/Å for the [100] and [001] dislocations, respectively. Both dislocations are associated with significant non-elastic displacement fields extending beyond the core with a radial component toward the dislocation line. The core of the [100] dislocation contains tetrahedrally coordinated magnesium, has a simple 2D structure and is spread parallel to (011) in a manner that suggests high mobility. In contrast, the core of the [001] dislocation has an extended and complex 3D structure involving the formation a large Si6O19 unit twisted around the dislocation line. This implies that movement of the [001] dislocation will be inhibited by the need to cleave Si–O bonds. These observations, combined with the anomalously low core energy of the [100] dislocation, explain the regular occurrence of [100] dislocations and very rare observation of [001] dislocations in experimentally deformed wadsleyite samples.
Translated title of the contributionSimulation of screw dislocations in wadsleyite
Original languageEnglish
Pages (from-to)301 - 310
Number of pages9
JournalPhysics and Chemistry of Minerals
Volume37
DOIs
Publication statusPublished - 2010

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