Crystal symmetry induced structure and bonding manipulation boosting thermoelectric performance of GeTe
Description
Rock-salt structured GeTe has been reckoned as a promising medium temperature thermoelectric material due to its decent thermal conductivity and multiple electronic valence bands that can be easily modified. However, the applications of GeTe-based thermoelectric materials are strongly impeded by their excessive hole concentration and detrimental phase transition, which deteriorates both thermoelectric performance and mechanical robustness. In this study, we simultaneously solve these two issues by co-doping Ti and Sb in GeTe, achieving an ultrahigh figure-of-merit (ZT) of ~2.2 at 725 K with an average ZT over 2.0 plateauing from 625 to 755 K. Our X-ray spectroscopy analysis and electron microscopy investigation, coupled with first-principle calculation, attribute the extraordinary thermoelectric performance of Ge1-x-yTixSbyTe to the synergetic effects of: a) resonant bonding properties induced by symmetrized crystal lattice; b) high Seebeck coefficient and quality factor due to enhanced band degeneracy and effective mass; c) optimized hole concentration by the aliovalent TiGe and SbGe substitution; and d) minimized thermal conductivity due to the evident frequency-selective phonon scattering by diverse types of defects. Our study indicates that manipulating structure and bonding properties by crystal symmetry modification can explore new-type and high-performance thermoelectric candidates in GeTe and its derivatives, as well as other phase-transition materials.
Impact and interest:
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ID Code: | 208804 | ||||
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Item Type: | Contribution to Journal (Journal Article) | ||||
Refereed: | Yes | ||||
ORCID iD: |
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Additional Information: | Funding Information: This study was financially supported by the Australian Research Council . The authors acknowledge the Microscopy Australia for providing characterization facilities and the Research Computing Centre at UQ for providing computation clusters, respectively. L. Kou and X. Tang acknowledge the grants of high-performance computer time from computing facility at the Queensland University of Technology, the Pawsey Supercomputing Centre and Australian National Facility. | ||||
Measurements or Duration: | 10 pages | ||||
Keywords: | Bonding properties, Crystal symmetry, Figure-of-merit, GeTe, Thermoelectric | ||||
DOI: | 10.1016/j.nanoen.2020.104740 | ||||
ISSN: | 2211-2855 | ||||
Pure ID: | 76048362 | ||||
Divisions: | Current > Research Centres > Centre for Materials Science Past > QUT Faculties & Divisions > Science & Engineering Faculty Current > QUT Faculties and Divisions > Faculty of Science Current > Schools > School of Mechanical, Medical & Process Engineering |
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Funding Information: | This study was financially supported by the Australian Research Council . The authors acknowledge the Microscopy Australia for providing characterization facilities and the Research Computing Centre at UQ for providing computation clusters, respectively. L. Kou and X. Tang acknowledge the grants of high-performance computer time from computing facility at the Queensland University of Technology, the Pawsey Supercomputing Centre and Australian National Facility. | ||||
Copyright Owner: | Crown Copyright © 2020 Published by Elsevier Ltd. | ||||
Copyright Statement: | This work is covered by copyright. Unless the document is being made available under a Creative Commons Licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. If the document is available under a Creative Commons License (or other specified license) then refer to the Licence for details of permitted re-use. It is a condition of access that users recognise and abide by the legal requirements associated with these rights. If you believe that this work infringes copyright please provide details by email to qut.copyright@qut.edu.au | ||||
Deposited On: | 11 Mar 2021 05:52 | ||||
Last Modified: | 01 Aug 2024 22:15 |
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