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Effects of Ta Substitution on the Microstructure and Transport Properties of Hf-Doped NbFeSb Half-Heusler Thermoelectric Materials

Farahi, Nader and Stiewe, Christian and Truong, Dao Y Nhi and Shi, Yixuan and Salamon, Soma and Landers, Joachim and Eggert, Benedikt and Wende, Heiko and de Boor, Johannes and Kleinke, Holger and Müller, Eckhard (2019) Effects of Ta Substitution on the Microstructure and Transport Properties of Hf-Doped NbFeSb Half-Heusler Thermoelectric Materials. ACS Applied Energy Materials. American Chemical Society (ACS). DOI: 10.1021/acsaem.9b01711 ISSN 2574-0962

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Abstract

This investigation demonstrates the effect of partial substitutions of Nb by refractory Ta on the microstructure and thermoelectric properties of Hf-doped NbFeSb materials. All the synthesized samples show a heavily doped semiconducting character with the electrical conductivity higher than 3500 Ω–1 cm–1 at 326 K. Furthermore, the samples containing Ta display consistently lower (∼10–13%) thermal conductivity of ∼7 W m–1 K–1 at 350 K compared to a value of ∼8 W m–1 K–1 at the same temperature for the nonsubstituted sample. The vivid impact of Ta substitutions on reducing the lattice thermal conductivity of NbFeSb based materials is chiefly due to the lattice disorder originating from the mass difference between Ta and Nb atoms, resulting in ∼28% reduction in lattice thermal conductivity of the Nb0.73Hf0.12Ta0.15FeSb sample at 350 K compared to the nonsubstituted sample. The results of our Mößbauer spectroscopy measurements exclude the possibility of mixed Fe occupancies. Although magnetic properties were not strongly modified by the Ta substitution, Nb0.83Hf0.12Ta0.05FeSb shows a magnetic phase transition at ∼150 K, which is not observed in Nb0.88Hf0.12FeSb. This could be caused by extrinsic defects and microstructure induced by Ta addition. All samples exhibit a similar maximum dimensionless figure of merit value, zTmax, of ∼0.75 at 800 K, which is comparable to the high efficiency materials previously reported in this system and makes them potential candidates to be utilized as p-type legs in half-Heusler based thermoelectric generators (TEG).

Item URL in elib:https://elib.dlr.de/130632/
Document Type:Article
Title:Effects of Ta Substitution on the Microstructure and Transport Properties of Hf-Doped NbFeSb Half-Heusler Thermoelectric Materials
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Farahi, Nadergerman aerospace center, institute of materials research, köln, germanyUNSPECIFIED
Stiewe, ChristianGerman aerospace center, Institute of materials research, Köln, Germanyhttps://orcid.org/0000-0002-1895-9258
Truong, Dao Y NhiGerman Aerospace Center, Institute of Materials Research, Köln, GermanyUNSPECIFIED
Shi, YixuanDepartment of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1, CanadaUNSPECIFIED
Salamon, SomaFaculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, GermanyUNSPECIFIED
Landers, JoachimFaculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, GermanyUNSPECIFIED
Eggert, BenediktFaculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057 Duisburg, GermanyUNSPECIFIED
Wende, HeikoUNSPECIFIEDUNSPECIFIED
de Boor, Johannesgerman aerospace center, institute of materials research, köln, germanyhttps://orcid.org/0000-0002-1868-3167
Kleinke, HolgerDepartment of Chemistry and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, CanadaUNSPECIFIED
Müller, EckhardGerman aerospace center, Institute of materials research, Köln, Germany and Institute for inorganic and analytical chemistry, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 58, 35392 Gießen, GermanyUNSPECIFIED
Date:4 November 2019
Journal or Publication Title:ACS Applied Energy Materials
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1021/acsaem.9b01711
Publisher:American Chemical Society (ACS)
ISSN:2574-0962
Status:Published
Keywords:Thermoelectric; half-Heusler; antimonide; alloying; doping
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: Yasseri, Mohammad
Deposited On:15 Nov 2019 15:21
Last Modified:14 Dec 2019 04:24

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