The dislocation core structures and Peierls stresses of wadsleyite, a high-pressure mineral present in the Earth’s mantle were determined. A Peierls–Nabarro model combined with a finite-element method was used into which two-dimensional generalized stacking fault energies were introduced. Several potential slip planes of wadsleyite were considered. The results showed that dislocations in this mineral could exhibit complex dislocation cores with linear or non-collinear dissociation and even three-dimensional dislocation cores. The calculation of the Peierls stresses furnished information on the potential activity of slip systems governing the plasticity of wadsleyite. This study confirmed experimental observations that ½<111>{101} was the easiest slip system in this structure at high pressures and that [100](010) was the second-easiest. Both of these easy-slip systems had dislocations which dissociated into collinear partial dislocations. In contrast, [010] dislocations with very large Burgers vectors (11.2Å) were stabilized by a complex dissociations involving four partial dislocations.

Plastic Deformation of Wadsleyite: IV Dislocation Core Modelling Based on the Peierls–Nabarro–Galerkin Model. A.Metsue, P.Carrez, C.Denoual, D.Mainprice, P.Cordier: Acta Materialia, 2010, 58[5], 1467-78