Exploring the thermoelectric behavior of spark plasma sintered Fe7-xCoxS8 compounds

Sulfide-based materials are emerging as viable alternatives for the current state-of-the-art thermoelectric materials, which usually are composed of toxic, expensive and scarce elements. Here, a systematic study of one such inexpensive and environmentally friendly sulfide-based system, i.e. Fe7-xCox...

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Bibliographic Details
Published in:Journal of alloys and compounds 2020-04, Vol.819, p.152999, Article 152999
Main Authors: Simon, Juliette, Guélou, Gabin, Srinivasan, Bhuvanesh, Berthebaud, David, Mori, Takao, Maignan, Antoine
Format: Article
Language:English
Subjects:
Chemical Sciences
Chemical synthesis
Co-doped pyrrhotites
Current carriers
Electrical resistivity
Figure of merit
Improved power factor
Magnetic properties
Plasma sintering
Pyrrhotite
Spark plasma sintering
SPS
Structural transition
Substitution reactions
Sulfides
Superstructures
Thermal conductivity
Thermoelectric materials
Thermoelectrics
Transport properties
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Summary:Sulfide-based materials are emerging as viable alternatives for the current state-of-the-art thermoelectric materials, which usually are composed of toxic, expensive and scarce elements. Here, a systematic study of one such inexpensive and environmentally friendly sulfide-based system, i.e. Fe7-xCoxS8 pyrrhotite-type compounds that were synthesized by solid-state reaction and densified by Spark Plasma Sintering are investigated for their structural and thermoelectric properties. We report that substitution of Co for Fe in pyrrhotites: (i) induces structural transition from monoclinic 4C superstructure to trigonal 3C superstructure; (ii) modifies the magnetic behavior by decreasing the magnetic ordering temperature and magnetization; (iii) alters the type of dominant charge carriers (from p-to n-type) and enhances their electrical transport properties; (iv) mitigates the phonon contribution to the thermal conductivity; and (v) amplifies the thermoelectric figure of merit when compared with that of pristine pyrrhotites. •Thermoelectric behavior of Fe7-xCoxS8 compounds are explored for the first time.•Highly densified samples are obtained after SPS (∼97% of the theoretical density).•Co-doping improves the power factor and suppresses the thermal transport (phonons).•Structural, magnetic transitions are corroborated with experimental evidences.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2019.152999