First-principles density functional calculations were performed on the coherent (0 0 1) interface between spinel (MgAl2O4) and aluminium, focusing on the ion-exchange reaction at the interface. The exchange reaction occurs by diffusion of magnesium and aluminium ions in opposite directions across the interface, at a rate controlled by the surface-to-volume ratio of the MgAl2O4 particles. We investigate the hypothesis that the reaction may involve a net charge transfer, leading to the formation of an interface electric dipole, with a possible influence on the mechanical properties of the Al/MgAl2O4 composite. Our analysis of the electronic charge density accompanying the ion exchange reveals an electric dipole at the interface. Its formation is shown to be a consequence of the interface electronic structure, taking the form of screening effects occurring locally at the substitutional Al site and more diffusely over the whole interface region.

Dipole formation due to ion exchange processes at the metal-ceramic Al/MgAl2O4 (001) interface

SBAIZERO, ORFEO;DE VITA, ALESSANDRO
2007-01-01

Abstract

First-principles density functional calculations were performed on the coherent (0 0 1) interface between spinel (MgAl2O4) and aluminium, focusing on the ion-exchange reaction at the interface. The exchange reaction occurs by diffusion of magnesium and aluminium ions in opposite directions across the interface, at a rate controlled by the surface-to-volume ratio of the MgAl2O4 particles. We investigate the hypothesis that the reaction may involve a net charge transfer, leading to the formation of an interface electric dipole, with a possible influence on the mechanical properties of the Al/MgAl2O4 composite. Our analysis of the electronic charge density accompanying the ion exchange reveals an electric dipole at the interface. Its formation is shown to be a consequence of the interface electronic structure, taking the form of screening effects occurring locally at the substitutional Al site and more diffusely over the whole interface region.
2007
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/1709765
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