High Temperature Transport Properties of Colusite Cu24T2V2Ge6S32 (T = Ni, Co)
Résumé
Sulfur-based minerals have emerged as interesting candidates for thermoelectric applications at high temperatures, tetrahedrites and colusites being two prominent examples. Herein, we extend the investigations on the latter family by reporting on the synthesis and the hightemperature thermoelectric properties of two polycrystalline colusites Cu24Ni2V2Ge6S32 and Cu24Co2V2Ge6S32. Both samples were prepared by powder metallurgy and consolidated by spark plasma sintering (SPS). Successful substitution of Ni and Co for Cu was confirmed by powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) that further revealed a homogeneous distribution of the elements within the colusite matrix. The electrical resistivity and thermopower values measured in the Ni sample indicate a more pronounced metallic character with respect to the Co sample. These two samples exhibit very low lattice thermal conductivities of the order of 0.5 W m-1 K-1 at 690 K. Despite this remarkable property, the Ni and Co concentrations studied herein did not give rise to enhanced ZT values relative to the previously reported parent compound Cu26V2Ge6S32 with a peak ZT value of 0.5 at 690 K achieved in the Ni sample.
Domaines
MatériauxOrigine | Fichiers produits par l'(les) auteur(s) |
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