Isovalent substitution effects on thermoelectric transport properties of CoSbX (X = S, Se, Te) system

Hafiza Sajida Kousar, Divya Srivastava, Maarit Karppinen, Girish C. Tewari*

*Tämän työn vastaava kirjoittaja

Tutkimustuotos: LehtiartikkeliArticleScientificvertaisarvioitu

Abstrakti

We demonstrate a transition of the thermoelectric transport characteristics in the CoSbX (X = S, Se or Te) systems from a p-type semiconductor to metallic conductor with increasing size of the X constituent. From DFT calculations CoSbS is found as an indirect semiconductor with band-gap of 0.38 eV, while both CoSbSe and CoSbTe appear as metals. For the two metals, the calculations reveal two degenerate electron pockets (located near the U point for CoSbSe and near the T point for CoSbTe) and a hole pocket along the x-Gamma-y points. In line with the theoretical predictions, electrical transport measurements reveal semiconducting-type temperature dependence of resistivity and positive room-temperature Seebeck coefficient (+570 mu V K-1) for CoSbS, and metallic-type temperature dependence for CoSbSe and CoSbTe with negative Seebeck coefficient (-14 and -7.5 mu V K-1). The Hall coefficient is positive for CoSbS(Se) and negative for CoSbTe. Room-temperature charge carrier densities were estimated at 3 x 10 (18)/similar to 10(21)/similar to 10(22) cm(-3) for CoSbS/CoSbSe/CoSbTe. Thermal conductivity is dominated by lattice rather than electronic contribution, the RT value being of the roughly same magnitude for all the three compounds. The temperature dependence of thermal conductivity bear resemblance to a typical semiconductor in the case of CoSbS and to a metallic alloy for CoSbSe and CoSbTe.

AlkuperäiskieliEnglanti
Artikkeli405704
Sivumäärä9
JulkaisuJournal of physics: Condensed matter
Vuosikerta31
Numero40
DOI - pysyväislinkit
TilaJulkaistu - 9 lokakuuta 2019
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

Projektit

  • 2 Päättynyt

TEOX: Maankuoren yleisten alkuaineiden oksideihin perustuvat termosähköiset materiaalit

Aleksandrova, I., Tiittanen, T., Karppinen, M. & Revitzer, H.

01/09/201523/09/2019

Projekti: Academy of Finland: Other research funding

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