Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion

Dislocations are known to influence the formation and migration of point defects in crystalline materials. We use a recently developed method for the simulation of the cores of dislocations in ionic materials to study the energy associated with the formation of point defects close to the core of a ½...

Full description

Bibliographic Details
Main Authors:	Zhang, Feiwu, Walker, A., Wright, K., Gale, Julian
Format:	Journal Article
Published:	The Royal Society of Chemistry 2010
Online Access:	http://hdl.handle.net/20.500.11937/29735

id	curtin-20.500.11937-29735
recordtype	eprints
spelling	curtin-20.500.11937-297352017-09-13T15:53:16Z Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion Zhang, Feiwu Walker, A. Wright, K. Gale, Julian Dislocations are known to influence the formation and migration of point defects in crystalline materials. We use a recently developed method for the simulation of the cores of dislocations in ionic materials to study the energy associated with the formation of point defects close to the core of a ½<110>{10} edge dislocation in MgO. These are then compared with the energies for the same point defects in otherwise perfect MgO. It is found that all of the defect species are bound to the dislocation core, with binding energies of between 1.5 and 2.0 eV. Vacancies are found to be most stable when they remove under-coordinated ions at the tip of the extra half plane, while the impurities are most stable within the dilatational stress field below the glide plane. By mapping the distribution of energies for point defects around the dislocation line we reveal the coupling between the effective point defect size and the stress field associated with the dislocation. We also examine the energy barrier to diffusion of vacancies along the dislocation line and find that vacancy migration along the dislocation line will be substantially enhanced compared to migration through the dislocation-free crystal structure. Activation energies are 0.85-0.92 of the barrier in the perfect crystal, demonstrating the importance of pipe diffusion along extended defects for low temperature mobility in ionic materials. 2010 Journal Article http://hdl.handle.net/20.500.11937/29735 10.1039/C0JM01550D The Royal Society of Chemistry fulltext
repository_type	Digital Repository
institution_category	Local University
institution	Curtin University Malaysia
building	Curtin Institutional Repository
collection	Online Access
description	Dislocations are known to influence the formation and migration of point defects in crystalline materials. We use a recently developed method for the simulation of the cores of dislocations in ionic materials to study the energy associated with the formation of point defects close to the core of a ½<110>{10} edge dislocation in MgO. These are then compared with the energies for the same point defects in otherwise perfect MgO. It is found that all of the defect species are bound to the dislocation core, with binding energies of between 1.5 and 2.0 eV. Vacancies are found to be most stable when they remove under-coordinated ions at the tip of the extra half plane, while the impurities are most stable within the dilatational stress field below the glide plane. By mapping the distribution of energies for point defects around the dislocation line we reveal the coupling between the effective point defect size and the stress field associated with the dislocation. We also examine the energy barrier to diffusion of vacancies along the dislocation line and find that vacancy migration along the dislocation line will be substantially enhanced compared to migration through the dislocation-free crystal structure. Activation energies are 0.85-0.92 of the barrier in the perfect crystal, demonstrating the importance of pipe diffusion along extended defects for low temperature mobility in ionic materials.
format	Journal Article
author	Zhang, Feiwu Walker, A. Wright, K. Gale, Julian
spellingShingle	Zhang, Feiwu Walker, A. Wright, K. Gale, Julian Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion
author_facet	Zhang, Feiwu Walker, A. Wright, K. Gale, Julian
author_sort	Zhang, Feiwu
title	Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion
title_short	Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion
title_full	Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion
title_fullStr	Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion
title_full_unstemmed	Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion
title_sort	defects and dislocations in mgo: atomic scale models of impurity segregation and fast pipe diffusion
publisher	The Royal Society of Chemistry
publishDate	2010
url	http://hdl.handle.net/20.500.11937/29735
first_indexed	2018-09-06T21:30:32Z
last_indexed	2018-09-06T21:30:32Z
_version_	1610895256913444864

Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion

Similar Items