Affiliation:
1. Leibniz Institute for Solid State and Materials Research Dresden e.V. (IFW‐Dresden) 01069 Dresden Germany
2. Institute of Materials Science TUD Dresden University of Technology 01062 Dresden Germany
3. Department of Physics and Astronomy University of Missouri Columbia MO 65211 USA
4. Max‐Planck‐Institut für Eisenforschung GmbH 40237 Düsseldorf Germany
5. Institute of Applied Physics TUD Dresden University of Technology 01062 Dresden Germany
Abstract
AbstractThe thermoelectric figure‐of‐merit (zT) of p‐type MNiSn (M = Ti, Zr, or Hf) half‐Heusler compounds is lower than their n‐type counterparts due to the presence of a donor in‐gap state caused by Ni occupying tetrahedral interstitials. While ZrNiSn and TiNiSn, have been extensively studied, HfNiSn remains unexplored. Herein, this study reports an improved thermoelectric property in p‐type HfNi1−xCoxSn. By doping 5 at% Co at the Ni sites, the Seebeck coefficient becomes reaching a peak value exceeding 200 µV K−1 that breaks the record of previous reports. A maximum power factor of ≈2.2 mW m−1 K−2 at 973 K is achieved by optimizing the carrier concentration. The enhanced p‐type transport is ascribed to the reduced content of Ni defects, supported by first principle calculations and diffraction pattern refinement. Concomitantly, Co doping also softens the lattice and scatters phonons, resulting in a minimum lattice thermal conductivity of ≈1.8 W m−1 K−1. This leads to a peak zT of 0.55 at 973 K is realized, surpassing the best performing p‐type MNiSn by 100%. This approach offers a new method to manipulate the intrinsic atomic disorder in half‐Heusler materials, facilitating further optimization of their electronic and thermal properties.
Funder
Deutsche Forschungsgemeinschaft
Subject
Electrochemistry,Condensed Matter Physics,Biomaterials,Electronic, Optical and Magnetic Materials
Cited by
6 articles.
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