Chauhan, Nagendra S. and Bathula, Sivaiah and Gahtori, Bhasker and Kolen'ko, Yury, V. and Dhar, Ajay (2019) Enhanced Thermoelectric Performance in Hf-Free p-Type (Ti, Zr)CoSb Half-Heusler Alloys. Journal of Electronic Materials , 48 SI (10). pp. 6700-6709. ISSN 0361-5235

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High thermal conductivity and exorbitant cost of Hf has for a long time limited the prospects of half-Heusler (HH) alloys for applicability in thermoelectric (TE) energy conversion devices. This work demonstrates the implication of nanostructuring and efficacy of p-type acceptor dopant in (Ti,Zr)CoSb based HH alloys for enhancing the figure of merit (ZT) while eliminating the use of Hf. A series of (Ti,Zr)CoSb1-x(Si,Sn)(x) HH composition was synthesized using arc-melting and consolidated employing spark plasma sintering (SPS). The optimal doping of acceptor dopants, namely, Si and Sn significantly improves the power factor and strengthens the phonon scattering resulting in an enhanced TE performance with maximum ZT of 0.26 and 0.5 at 873 K, obtained for TiCoSb0.8Sn0.2 and ZrCoSb0.8Sn0.2, respectively. For further optimization, microstructural modifications by fine-tuning of the Ti to Zr ratio induces strain field effects and mass fluctuation in (Ti,Zr)CoSb0.8Sn0.2 compositions, which remarkably introduces additional phonon scattering resulting in maximum ZT similar to 0.8 at 873 K for the best performing Zr0.5Ti0.5CoSb0.8Sn0.2 compound. The current study provides a better understanding of p-type dopants in HH materials by which prospective high TE performance can be obtained in low-cost Hf-free p-type (Ti,Zr)CoSb half-Heusler alloys.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s Institute of Electrical and Electronics Engineers.
Subjects: Engineering > Electronics and Electrical Engineering
Materials Science
Applied Physics/Condensed Matter
Depositing User: Mr. Yogesh Joshi
Date Deposited: 06 Mar 2020 10:09
Last Modified: 06 Mar 2020 10:09

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