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Open AccessFeature PaperArticle

Substitution Versus Full-Heusler Segregation in TiCoSb

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Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK
2
Institute of Petroleum Engineering, School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh EH14 4AS, UK
*
Author to whom correspondence should be addressed.
Metals 2018, 8(11), 935; https://doi.org/10.3390/met8110935
Received: 18 October 2018 / Revised: 6 November 2018 / Accepted: 8 November 2018 / Published: 12 November 2018
(This article belongs to the Special Issue Heusler Compounds)
Half-Heuslers (HHs) are promising thermoelectric materials with great compositional flexibility. Here, we extend work on the p-type doping of TiCoSb using abundant elements. Ti0.7V0.3Co0.85Fe0.15Sb0.7Sn0.3 samples with nominal 17.85 p-type electron count were investigated. Samples prepared using powder metallurgy have negative Seebeck values, S ≤ −120 µV K−1, while arc-melted compositions are compensated semiconductors with S = −45 to +30 µV K−1. The difference in thermoelectric response is caused by variations in the degree of segregation of V(Co0.6Fe0.4)2Sn full-Heusler and Sn phases, which selectively absorb V, Fe, and Sn. The segregated microstructure leads to reduced lattice thermal conductivities, κlat = 4.5−7 W m−1 K−1 near room temperature. The largest power factor, S2/ρ = 0.4 mW m−1 K−2 and ZT = 0.06, is observed for the n-type samples at 800 K. This works extends knowledge regarding suitable p-type dopants for TiCoSb. View Full-Text
Keywords: Half-Heusler; TiCoSb; phase segregation; thermoelectric properties Half-Heusler; TiCoSb; phase segregation; thermoelectric properties
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Asaad, M.; Buckman, J.; Bos, J.-W.G. Substitution Versus Full-Heusler Segregation in TiCoSb. Metals 2018, 8, 935.

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