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Microstructural effects on thermoelectric efficiency: A case study on magnesium silicide

de Boor, Johannes and Dasgupta, Titas and Kolb, Hendrik and Compere, Camille and Kelm, Klemens and Müller, Eckhard (2014) Microstructural effects on thermoelectric efficiency: A case study on magnesium silicide. Acta Materialia, 77, pp. 68-75. Elsevier. DOI: 10.1016/j.actamat.2014.05.041 ISSN 1359-6454

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Abstract

Carrier transport and conversion efficiency of thermoelectric materials is not only governed by the intrinsic bulk material properties, but often heavily influenced by microstructural effects. Using Mg2Si—a very attractive, non-toxic and abundant material—as an example, the authors investigate the microstructural effects on thermoelectric transport in the material. Combining microstructural analysis (scanning electron microscopy, X-ray diffraction) with high-temperature transport measurements (Seebeck coefficient, electrical and thermal conductivity, charge carrier mobility), it is verified that small amounts of impurity phases can heavily impair electrical transport. Further electron microscopy studies confirm MgO functioning as a scattering center at the grain boundaries of the material. The effect of the impurity phases on the transport properties can be understood in a simple transport model based on a single parabolic band including grain boundary scattering. The model can be employed to assess material parameters such as the phonon deformation potential, the barrier height of the grain boundaries and the average size of the grains. Furthermore, the detrimental effect of MgO on thermoelectric efficiency is quantified. Compared with Sb-doped Mg2Si with optimized properties, a few per cent MgO decreases the average thermoelectric figure of merit by 30%.

Item URL in elib:https://elib.dlr.de/92545/
Document Type:Article
Title:Microstructural effects on thermoelectric efficiency: A case study on magnesium silicide
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
de Boor, JohannesGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Dasgupta, TitasGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Kolb, HendrikGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Compere, CamilleGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Kelm, KlemensGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Müller, EckhardGerman Aerospace Center, Institute of Materials Research, Köln, Germany and Justus Liebig University Giessen, Institute of Inorganic and Analytical Chemistry, 35392 Giessen, GermanyUNSPECIFIED
Date:27 June 2014
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:77
DOI :10.1016/j.actamat.2014.05.041
Page Range:pp. 68-75
Publisher:Elsevier
ISSN:1359-6454
Status:Published
Keywords:Silicides; Thermoelectric; Grain boundary scattering; High-temperature transport; Magnesium oxide
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Terrestrial Vehicles (old)
DLR - Research area:Transport
DLR - Program:V BF - Bodengebundene Fahrzeuge
DLR - Research theme (Project):V - Fahrzeugenergiesystem III (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Thermoelectric Materials and Systems
Deposited By: Zabrocki, Dr. Knud
Deposited On:01 Dec 2014 10:36
Last Modified:10 Jan 2019 15:45

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