Thermoelectric properties of the chalcopyrite Cu1−xMxFeS2−y series (M = Mn, Co, Ni). Issue 60 (8th June 2016)

• Record Type: Journal Article
• Authors: Lefèvre, Robin; Berthebaud, David; Mychinko, M. Yu.; Lebedev, Oleg I.; Mori, Takao; Gascoin, Franck; Maignan, Antoine
• Is Part Of: RSC advances. Volume 6:Issue 60(2016)
• Page Start: 55117
• Page End: 55124
• Publication Date: 2016-06-08
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra10046e
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : This study presents the thermoelectric properties of the substituted on the Cu site and/or sulfur deficiency CuFeS2 chalcopyrite based series Cu1− x M x FeS2− y (M = Mn, Co, Ni, x ≤ 0.05 and y ≤ 0.02). Abstract : The natural chalcopyrite mineral CuFeS2 is a semiconductor material with potential for thermoelectric applications. This study presents the thermoelectric properties – electrical resistivity ρ, Seebeck coefficient S and thermal conductivity κ – of the substituted on the Cu site and/or sulfur deficient CuFeS2 chalcopyrite based series Cu1− x M x FeS2− y (M = Mn, Co, Ni, x ≤ 0.05 and y ≤ 0.02). All samples have been densified by spark plasma sintering, allowing proper measurements of S, ρ and κ at high temperature. All compounds show n-type semiconducting properties with large absolute values of S, from −220 to −340 μV K −1 . Maximum ZT values up to 0.20 at 623 K were obtained for Cu0.97 Mn0.03 FeS2 and Cu0.98 Co0.02 FeS1.98 . The veracity of Mn for Cu substitution into the structure has been confirmed by EDS analyses, coupled to electron diffraction within a transmission electron microscope. The latter study demonstrates the existence of twinned domains. The thermal conductivity reaches values as low as κ ∼ 1.2 W m −1 K −1 at 623 K. The magnetic properties of a Mn substituted sample did not show any significant modification in the magnetic behavior compared to the pristine CuFeS2 compound. The small negative magnetoresistance observed in CuFeS2 of about −2% at 5 K in 9 T is degraded in the Mn substituted sample.