Copper-Rich Thermoelectric Sulfides Size-Mismatch Effect and Chemical Disorder in the [TS ]Cu Complexes of Cu T Ge S (T=Cr, Mo, W) Colusites

Abstract : Herein, we investigate the Mo and W substitution for Cr in synthetic colusite, Cu Cr Ge S . Primarily, we elucidate the origin of extremely low electrical resistivity which does not compromise the Seebeck coefficient and leads to outstanding power factors of 1.94 mW m  K at 700 K in Cu Cr Ge S . We demonstrate that the abnormally long iono-covalent T-S bonds competing with short metallic Cu-T interactions govern the electronic transport properties of the conductive "Cu S " framework. We address the key role of the cationic size-mismatch at the core of the mixed tetrahedral-octahedral complex over the transport properties. Two essential effects are identified 1) only the tetrahedra that are directly bonded to the [TS ]Cu complex are significantly distorted upon substitution and 2) the major contribution to the disorder is localized at the central position of the mixed tetrahedral-octahedral complex, and is maximized for x=1, i.e. for the highest cationic size-variance, σ .
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https://hal-univ-rennes1.archives-ouvertes.fr/hal-02307079
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Submitted on : Monday, October 7, 2019 - 11:52:00 AM
Last modification on : Tuesday, November 12, 2019 - 5:01:45 PM

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Ventrapati Pavan Kumar, Gabin Guélou, Pierric Lemoine, Bernard Raveau, Andrew R Supka, et al.. Copper-Rich Thermoelectric Sulfides Size-Mismatch Effect and Chemical Disorder in the [TS ]Cu Complexes of Cu T Ge S (T=Cr, Mo, W) Colusites. Angewandte Chemie International Edition, Wiley-VCH Verlag, 2019, 58 (43), pp.15455-15463. ⟨10.1002/anie.201908579⟩. ⟨hal-02307079⟩

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