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Ab-Initio Theory of Grain-Boundary Segregation in α-Alumina: Energetics, Atomistic and Electronic Structures

Published online by Cambridge University Press:  11 February 2011

Stefano Fabris  and
Christian Elsässer
Stefano Fabris
Affiliation:
Istituto Nazionale per la Fisica della Materia (INFM) and Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Beirut 2–4, Trieste I-34014, Italy. Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany.
Christian Elsässer
Affiliation:
Fraunhofer-Institut für Werkstoffmechanik, Wöhlerstr. 11–13, D-79108 Freiburg, Germany Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany.
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Abstract

The modifications in atomistic structure, chemical bonding, and energetics induced by sub-stitutional cation impurities isolated in bulk and segregated at grain boundaries of α-Al2O3 were investigated by first-principles electronic-structure calculations. The dependency of these modifications on the boundary type, species and concentration of defects, was studied by selecting the following variety of systems: two different twin boundaries (the prismatic Σ3 (1010) and the pyramidal Σ13 (1014) twins), five cation impurities X (X=Ti, Sc, Y, Ca, and La), and two concentration regimes for the segregant (≈ 3 and ≈ 6 atoms/nm2). A partial covalent character is found to be a distinctive feature of the X-O bond in both bulk and interfacial atomic environments, and to drive the structural distortions of the octahedral XO6 clusters. The energetics of segregation reveals a linear relationship between segregation energy and impurity size.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 751: Symposium Z – Structure-Property Relationships of Oxide Surfaces and Interfaces II , 2002 , Z1.2
Copyright
Copyright © Materials Research Society 2003

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References

REFERENCES

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