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Analyzing thermoelectric transport in n-type Mg2Si0. 4Sn0. 6 and correlation with microstructural effects: An insight on the role of Mg

Sankhla, Aryan and Hasbuna, Kamila and Kelm, Klemens and Müller, Eckhard and de Boor, Johannes (2020) Analyzing thermoelectric transport in n-type Mg2Si0. 4Sn0. 6 and correlation with microstructural effects: An insight on the role of Mg. Acta Materialia (199), pp. 85-95. Elsevier. doi: 10.1016/j.actamat.2020.07.045. ISSN 1359-6454.

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Abstract

Fundamental material parameters governing the carrier transport in thermoelectric materials are affected by microstructural characteristics. We have investigated the effects of compaction duration on microstructure and the thermoelectric properties of Sb doped Mg2Si0.4Sn0.6. The transport properties show drastic changes with increasing compaction duration from 10 min to 40 min. A TEM-EDS analysis on samples sintered for 20 min and 40 min highlights Mg depleted grain boundaries and local compositional inhomogeneities but gives no indications for dopant loss. The transport properties were analyzed using a single parabolic band (SPB) model, and the observed changes can be attributed to carrier (n) loss, diminished carrier mobility (μ_0) and a reduction in lattice thermal conductivity (κ_lat). Comparatively stronger carrier scattering in longer sintered sample is a combined effect of increasing electron-phonon interaction (higher E_Def) and local compositional inhomogeneities in the material which are both linked to Mg depletion. The transport behavior of these samples can be fully captured by the SPB model only after the addition of grain boundary scattering in conjunction to acoustic phonon and alloy scattering. Furthermore, compensation between a lower κ_lat and μ_0 of the longer sintered sample led to a similar zT_max = 1.3±0.18 and an only marginally reduced performance parameter β. While it is evident that Mg deficiency modifies the transport properties, the thermoelectric performance is only mildly affected and a Mg2(Si,Sn) based TE device can therefore withstand some Mg loss without a deterioration of its performance.

Item URL in elib:https://elib.dlr.de/137148/
Document Type:Article
Title:Analyzing thermoelectric transport in n-type Mg2Si0. 4Sn0. 6 and correlation with microstructural effects: An insight on the role of Mg
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Sankhla, Aryangerman aerospace center, institute of materials research, köln, germanyhttps://orcid.org/0000-0002-1527-6902
Hasbuna, Kamilagerman aerospace center, institute of materials research, köln, germanyUNSPECIFIED
Kelm, KlemensGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Müller, EckhardInstitute of Materials Research, German Aerospace Center (DLR), Institute of Materials Research – Thermoelectric Materials and Systems, 51147 Köln Porz-Wahnheide, Linder Höhe, Germany and Justus Liebig University Giessen, Institute of Inorganic and AnalytUNSPECIFIED
de Boor, JohannesGerman aerospace center, institute of materials research, köln, germanyhttps://orcid.org/0000-0002-1868-3167
Date:15 October 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
DOI :10.1016/j.actamat.2020.07.045
Page Range:pp. 85-95
Publisher:Elsevier
ISSN:1359-6454
Status:Published
Keywords:Sintering, Transmission electron microscopy (TEM), Electronic band structure, Analytical modeling
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Road Transport
DLR - Research area:Transport
DLR - Program:V ST Straßenverkehr
DLR - Research theme (Project):V - NGC Antriebssystem und Energiemanagement
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Thermoelectric Materials and Systems
Deposited By: Frank, Adina
Deposited On:06 Nov 2020 09:33
Last Modified:06 Nov 2020 09:33

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