Crystal symmetry induced structure and bonding manipulation boosting thermoelectric performance of GeTe

Li, Meng and Hong, Min and Tang, Xiao and Sun, Qiang and Lyu, Wan-Yu and Xu, Sheng-Duo and Kou, Liang-Zhi and Dargusch, Matthew and Zou, Jin and Chen, Zhi-Gang ORCID: https://orcid.org/0000-0002-9309-7993 (2020) Crystal symmetry induced structure and bonding manipulation boosting thermoelectric performance of GeTe. Nano Energy, 73:104740. pp. 1-10. ISSN 2211-2855


Abstract

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.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Date Deposited: 21 Jan 2021 04:32
Last Modified: 29 Jan 2021 04:37
Uncontrolled Keywords: GeTe; Thermoelectric; Crystal symmetry; Bonding properties; Figure-of-merit
Fields of Research (2008): 02 Physical Sciences > 0204 Condensed Matter Physics > 020404 Electronic and Magnetic Properties of Condensed Matter; Superconductivity
09 Engineering > 0912 Materials Engineering > 091205 Functional Materials
Fields of Research (2020): 40 ENGINEERING > 4016 Materials engineering > 401605 Functional materials
51 PHYSICAL SCIENCES > 5104 Condensed matter physics > 510404 Electronic and magnetic properties of condensed matter; superconductivity
Funding Details:
Identification Number or DOI: https://doi.org/10.1016/j.nanoen.2020.104740
URI: http://eprints.usq.edu.au/id/eprint/40556

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