Thermoelectric properties of InCoSb: role of formed InSb precipitates, Sb overstoichiometry, and processing conditions

In-filled skutterudites In x Co 4 Sb 12 have attracted much attention due to their relatively high thermoelectric performance, which, in turn, is attributed to the In atoms acting as rattlers in the skutterudite voids and to the formation of InSb precipitates when the In solubility limit is exceeded...

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Published inJournal of materials chemistry. A, Materials for energy and sustainability Vol. 11; no. 5; pp. 2334 - 2342
Main Authors Ivanova, Alexandra, Novitskii, Andrei, Serhiienko, Illia, Guélou, Gabin, Sviridova, Tatyana, Novikov, Sergey, Gorshenkov, Mikhail, Bogach, Aleksei, Korotitskiy, Andrey, Voronin, Andrei, Burkov, Alexander, Mori, Takao, Khovaylo, Vladimir
Format Journal Article
Published 31.01.2023
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Summary:In-filled skutterudites In x Co 4 Sb 12 have attracted much attention due to their relatively high thermoelectric performance, which, in turn, is attributed to the In atoms acting as rattlers in the skutterudite voids and to the formation of InSb precipitates when the In solubility limit is exceeded (0.22 ≤ x max ≤ 0.27). In this work, to suppress the formation of the unwanted CoSb 2 phase and favor the formation of InSb precipitates, the following composition of In 1 Co 4 Sb 12+ δ with In concentration much higher than the solubility limit and Sb overstoichiometry was used. Three sets of bulk specimens with a nominal composition of In 1 Co 4 Sb 12+ δ were synthesized by conventional induction melting followed by (1) ball milling (BM) and spark plasma sintering (SPS), (2) BM and SPS followed by high-temperature annealing, and (3) melt spinning and SPS. The utilization of different sample preparation methods and processing conditions leads to samples with different microstructures and InSb precipitates of different shapes, sizes, and distributions. Thus, for all samples with the same nominal composition of In 1 Co 4 Sb 12+ δ , zT max varies from 0.7 to 1.3 at 673 K only because of microstructural modification. A maximum zT value of around 1.3 was obtained at 673 K for the sample prepared using induction melting followed by annealing, melt spinning, and SPS. The demonstration of strong coupling between the processing conditions, microstructure, distribution, shape, and size of InSb precipitates in In-filled Co 4 Sb 12 .
Bibliography:https://doi.org/10.1039/d2ta07625j
Electronic supplementary information (ESI) available: Scheme of the fabrication route for the samples under study; XRD data for all the samples before sintering; Rietveld refinement and its results; EBSD analysis data; SEM images of the fracture surfaces of the samples under study; SEM images of the polished surfaces with the corresponding EDX mapping; field and angular dependencies of the Hall resistance; comparison of the thermoelectric properties of the MSA sample with those from previous reports; comparison of the charge carrier concentration and mobility of all the samples with those from the literature. See DOI
ISSN:2050-7488
2050-7496
DOI:10.1039/d2ta07625j