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Aluminium self-diffusion in high-purity a-Al2O3: Comparison of Ti-doped and undoped single crystals

Fielitz, Peter and Ganschow, Steffen and Kelm, Klemens and Borchardt, Günter (2020) Aluminium self-diffusion in high-purity a-Al2O3: Comparison of Ti-doped and undoped single crystals. Acta Materialia, 195, pp. 416-424. Elsevier. doi: 10.1016/j.actamat.2020.05.030. ISSN 1359-6454.

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Official URL: https://www.sciencedirect.com/science/article/abs/pii/S1359645420303773

Abstract

Reliable data on self-diffusion of aluminium in a-Al2O3 are scarce and do not yet enable deriving quantitative conclusions about the impact of deliberate aliovalent doping. Therefore, the present study (1280 � T/ °C � 1500, pO2 = 200 mbar) was based on carefully grown high-purity single crystals doped with Ti. The experimentally determined 26Al tracer diffusivity increased with the Ti concentration and confirmed the incorporation of Ti on Al sites, Ti�Al, with aluminium vacancies, V000Al , formed for charge compensation. The observed relation between these two point defect concentrations as a function of the Ti concentration and the temperature can be quantitatively modelled by taking into account probable Ti� Al : V000Al clusters. Using binding energy starting values from published computer simulations for the fit procedure cluster binding energies are obtained. The surprisingly high Aldiffusivity in undoped samples can be tentatively rationalised by injection of Al interstitials at the liquid/solid interface because of the low oxygen potential during the crystal growth process.

Item URL in elib:https://elib.dlr.de/136971/
Document Type:Article
Title:Aluminium self-diffusion in high-purity a-Al2O3: Comparison of Ti-doped and undoped single crystals
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Fielitz, PeterTechnische Universität Clausthal, Institut für Metallurgie, Robert-Koch-Str. 42, D-38678 Clausthal-ZellerfeldUNSPECIFIED
Ganschow, SteffenLeibniz-Institut fur Kristallzüchtung, Max-Born-Str. 2, D-12489 BerlinUNSPECIFIED
Kelm, KlemensKlemens.Kelm (at) dlr.deUNSPECIFIED
Borchardt, GünterTechnische Universität Clausthal, Institut für Metallurgie, Robert-Koch-Str. 42, D-38678 Clausthal-ZellerfeldUNSPECIFIED
Date:22 May 2020
Journal or Publication Title:Acta Materialia
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:195
DOI :10.1016/j.actamat.2020.05.030
Page Range:pp. 416-424
Publisher:Elsevier
ISSN:1359-6454
Status:Published
Keywords:Alumina Ti-doped Tracer diffusion 26Al SIMS Defect clusters
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transportation
DLR - Research area:Raumfahrt
DLR - Program:R RP - Space Transportation
DLR - Research theme (Project):R - Wiederverwendbare Raumfahrtsysteme (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Microanalysis
Deposited By: Kelm, Dr. Klemens
Deposited On:03 Nov 2020 10:17
Last Modified:03 Nov 2020 10:17

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