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Interstitial Defect Modulation Promotes Thermoelectric Properties of p ‐Type HfNiSn

Ai, Xin; Xue, Wenhua; Giebeler, Lars; Pérez, Nicolás; Lei, Binghua; Zhang, Yue; Zhang, Qihao 1; Nielsch, Kornelius; Wang, Yumei ; He, Ran
1 Lichttechnisches Institut (LTI), Karlsruher Institut für Technologie (KIT)

Abstract:

The n-type MNiSn (M = Ti, Zr, or Hf ) half-Heusler compounds are reported as promising medium- and high-temperature thermoelectric materials; however, their p-type counterparts have suffered from poor performance due to the in-gap state caused by Ni occupying the tetrahedral interstitials. Inspired by recent findings that thermoelectric performance can be enhanced without substantially increasing compositional or structural complexity, the study attempts to manipulate the Ni interstitial defects by altering the stoichiometric composition. The results show that when HfNiSn is prepared
by a non-equilibrium method, the intrinsic Ni defects are effectively
suppressed by simply reducing the nominal Ni content. The suppression of Ni defects not only leads to a larger bandgap, but also attenuates carrier scattering to achieve higher mobility. After further optimization of the carrier concentration, the p-type HfNi$_{0.85}$Co$_{0.05}$ Sn achieves a maximum power factor
of 3100 μW m$^{-1}$ K$^{-2}$ at 773 K and a peak zT of ≈0.7 at 973 K, both of which are superior to that of the state-of-the-art p-type MNiSn. The results demonstrate that the off-stoichiometric ratio is effective in decoupling electron-phonon transports of thermoelectric materials with massive intrinsic defects, and also contribute to understanding the role of defect modulation in optimizing thermoelectric properties.


Verlagsausgabe §
DOI: 10.5445/IR/1000172929
Veröffentlicht am 29.07.2024
Originalveröffentlichung
DOI: 10.1002/aenm.202401345
Scopus
Zitationen: 1
Web of Science
Zitationen: 1
Dimensions
Zitationen: 1
Cover der Publikation
Zugehörige Institution(en) am KIT Lichttechnisches Institut (LTI)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 10.2024
Sprache Englisch
Identifikator ISSN: 1614-6832, 1614-6840
KITopen-ID: 1000172929
Erschienen in Advanced Energy Materials
Verlag Wiley-VCH Verlag
Band 14
Heft 38
Seiten Art.-Nr.: 2401345
Vorab online veröffentlicht am 14.07.2024
Nachgewiesen in Dimensions
Scopus
Web of Science
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