Atomistic Modeling of Effect of Mg on Oxygen Vacancy Diffusion in α-Alumina

Tewari, Abhishek; Aschauer, Ulrich Johannes; Bowen, Paul (2014). Atomistic Modeling of Effect of Mg on Oxygen Vacancy Diffusion in α-Alumina. Journal of the American Ceramic Society, 97(8), pp. 2596-2601. American Ceramic Society 10.1111/jace.13008

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Oxygen diffusion plays an important role in grain growth and densification during the sintering of alumina ceramics and governs high-temperature processes such as creep. The atomistic mechanism for oxygen diffusion in alumina is, however, still debated; atomistic calculations not being able to match experimentally determined activation energies for oxygen vacancy diffusion. These calculations are, however, usually performed for perfectly pure crystals, whereas virtually every experimental alumina sample contains a significant fraction of impurity/dopants ions. In this study, we use atomistic defect cluster and nudged elastic band (NEB) calculations to model the effect of Mg impurities/dopants on defect binding energies and migration barriers. We find that oxygen vacancies can form energetically favorable clusters with Mg, which reduces the number of mobile species and leads to an additional 1.5 eV energy barrier for the detachment of a single vacancy from Mg. The migration barriers of diffusive jumps change such that an enhanced concentration of oxygen vacancies is expected around Mg ions. Mg impurities were also found to cause destabilization of certain vacancy configurations as well as enhanced vacancy–vacancy interaction.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Aschauer, Ulrich Johannes

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry
600 Technology > 620 Engineering

ISSN:

0002-7820

Publisher:

American Ceramic Society

Language:

English

Submitter:

Ulrich Johannes Aschauer

Date Deposited:

12 Jan 2016 16:53

Last Modified:

26 Jan 2016 09:54

Publisher DOI:

10.1111/jace.13008

BORIS DOI:

10.7892/boris.72982

URI:

https://boris.unibe.ch/id/eprint/72982

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