Strong phonon–phonon interactions securing extraordinary thermoelectric Ge1–xSbxTe with Zn-alloying-induced band alignment
Article
Article Title | Strong phonon–phonon interactions securing extraordinary thermoelectric Ge1–xSbxTe with Zn-alloying-induced band alignment |
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ERA Journal ID | 1359 |
Article Category | Article |
Authors | Hong, Min (Author), Wang, Yuan (Author), Feng, Tianli (Author), Sun, Qiang (Author), Xu, Shengduo (Author), Matsumura, Syo (Author), Pantelides, Sokrates T. (Author), Zou, Jin (Author) and Chen, Zhi-Gang (Author) |
Journal Title | Journal of the American Chemical Society |
Journal Citation | 141 (4), pp. 1742-1748 |
Number of Pages | 7 |
Year | 2019 |
Place of Publication | United States |
ISSN | 0002-7863 |
1520-5126 | |
Digital Object Identifier (DOI) | https://doi.org/10.1021/jacs.8b12624 |
Web Address (URL) | https://pubs.acs.org/doi/abs/10.1021/jacs.8b12624 |
Abstract | The ability of substitution atoms to decrease thermal conductivity is usually ascribed to the enhanced phonon-impurity scattering by assuming the original phonon dispersion relations. In this study, we find that 10% SbGe alloying in GeTe modifies the phonon dispersions significantly, closes the acoustic–optical phonon band gap, increases the phonon–phonon scattering rates, and reduces the phonon group velocities. These changes, together with grain boundaries, nanoprecipitates, and planar vacancies, lead to a significant decrease in the lattice thermal conductivity. In addition, an extra 2–6% Zn alloying decreases the energy offset between valence band edges at L and Σ points in Ge1–xSbxTe that is found to be induced by the Ge 4s2 lone pairs. Since Zn is free of s2 lone pair electrons, substituting Ge with Zn atoms can consequently diminish the Ge 4s2 lone-pair characters and reduce the energy offset, resulting in two energetically merged valence band maxima. The refined band structures render a power factor up to 40 μW cm–1 K–2 in Ge0.86Sb0.1Zn0.04Te. Ultimately, a superhigh zT of 2.2 is achieved. This study clarifies the impacts of high-concentration substitutional atoms on phonon band structure, phonon–phonon scattering rates, and the convergence of electron valence band edges, which could provide guidelines for developing high-performance thermoelectric materials. |
Keywords | high-performance; progress; figure; merit; SNTE |
ANZSRC Field of Research 2020 | 401605. Functional materials |
Public Notes | Files associated with this item cannot be displayed due to copyright restrictions. |
Byline Affiliations | Centre for Future Materials |
Vanderbilt University, United States | |
University of Queensland | |
Kyushu University, Japan | |
Institution of Origin | University of Southern Queensland |
Funding source | Australian Research Council (ARC) |
https://research.usq.edu.au/item/q5070/strong-phonon-phonon-interactions-securing-extraordinary-thermoelectric-ge1-xsbxte-with-zn-alloying-induced-band-alignment
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