Title :

Why do compact grain boundary complexions prevail in rock-salt materials?

Author(s) :

Hirel, Pierre [Auteur]
Unité Matériaux et Transformations (UMET) - UMR 8207
Carrez, Philippe [Auteur]
Unité Matériaux et Transformations (UMET) - UMR 8207
Cordier, Patrick [Auteur]
Unité Matériaux et Transformations (UMET) - UMR 8207

Journal title :

Acta Materialia

Abbreviated title :

Acta Materialia

Pages :

118297

Publisher :

Elsevier BV

Publication date :

2022-08

ISSN :

1359-6454

English keyword(s) :

Numerical simulation
MgO
Grain boundary

HAL domain(s) :

Physique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]
Planète et Univers [physics]/Sciences de la Terre

English abstract : [en]

Over 40 years of studies of grain boundaries in ionic rock-salt materials have left the community divided. On one hand, numerical simulations systematically predict open, hollow structural units to be the ground state. On ...
Show more >Over 40 years of studies of grain boundaries in ionic rock-salt materials have left the community divided. On one hand, numerical simulations systematically predict open, hollow structural units to be the ground state. On the other, most recent experiments report compact structures to be the norm. To reconcile modelling with experimental evidence, we investigate the stability of three high-angle symmetric tilt grain boundaries in magnesium oxide MgO with respect to the presence of charge-neutral vacancy pairs. We demonstrate that although open structural units are energetically the most favourable, they are easily destabilized by vacancies. It follows that open complexions can never be at equilibrium with the surrounding grains at finite temperature. On the contrary, compact structural units can accommodate a wide range of defects concentrations, and are much more resilient with respect to the absorption of vacancies. These results highlight the limitations of studies that consider only the ground state, and stress the importance of accounting for the presence of other defects when modelling grain boundaries in ionic materials.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

European Project :

Rheology of Earth materials: closing the gap between TIMEscales in the laboratory and in the MANtle

Administrative institution(s) :

Université de Lille
CNRS
INRAE
ENSCL

Collections :

• Unité Matériaux et Transformations (UMET) - UMR 8207

Research team(s) :

Plasticité

Submission date :

2022-08-29T13:00:45Z
2022-09-02T08:16:39Z