Skelton, R and Walker, AM orcid.org/0000-0003-3121-3255 (2018) Lubrication of dislocation glide in MgO by hydrous defects. Physics and Chemistry of Minerals, 45 (8). pp. 713-726. ISSN 0342-1791
Abstract
Water-related defects, principally in the form of protonated cation vacancies, are potentially able to weaken minerals under high-stress or low-temperature conditions by reducing the Peierls stress required to initiate dislocation glide. In this study, we use the Peierls-Nabarro (PN) model to determine the effect of protonated Mg vacancies on the 1/2<110>{110} and 1/2<110>{100} slip systems in MgO. This PN model is parameterized using generalized stacking fault energies calculated using plane-wave density functional theory, with and without protonated Mg vacancies present at the glide plane. It found that these defects increase dislocation core widths and reduce the Peierls stress over the entire pressure range 0-125 GPa. Furthermore, 1/2<110>{110} slip is found to be more sensitive to the presence of protonated vacancies which increases in the pressure at which {100} becomes the easy glide plane for 1/2<110> screw dislocations. These results demonstrate, for a simple mineral system, that water-related defects can alter the deformation behavior of minerals in the glide-creep regime by reducing the stress required to move dislocations by glide. (Mg, Fe)O is the most anisotropic mineral in the Earth's lower mantle, so the differential sensitivity of the major slip systems in MgO to hydrous defects has potential implications for the interpretation of the seismic anisotropy in this region.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © Springer-Verlag GmbH Germany, part of Springer Nature 2018. This is a post-peer-review, pre-copyedit version of an article published in Physics and Chemistry of Minerals. The final authenticated version is available online at: https:// doi.org/10.1007/s00269-018-0957-y |
Keywords: | MgO; dislocations; hydrous defects;; Peierls stress; Peierls-Nabarro modeling |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Funding Information: | Funder Grant number NERC NE/K008803/1 NERC NE/M000044/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 21 Feb 2018 16:00 |
Last Modified: | 22 Feb 2019 01:39 |
Status: | Published |
Publisher: | Springer Nature |
Identification Number: | 10.1007/s00269-018-0957-y |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:127674 |