Sun, Qiang and Shi, Xiao-Lei 
ORCID: https://orcid.org/0000-0003-0905-2547 and Hong, Min ORCID: https://orcid.org/0000-0002-6469-9194 and Yin, Yu and Xu, Sheng-Duo and Chen, Jie and Yang, Lei and Zou, Jin and Chen, Zhi-Gang ORCID: https://orcid.org/0000-0002-9309-7993
(2021)
Achieving High-Performance Ge0.92Bi0.08Te Thermoelectrics via LaB6-Alloying-Induced Band Engineering and Multi-Scale Structure Manipulation.
Small:2105923.
pp. 1-10.
ISSN 1613-6810
Abstract
In this work, a LaB6-alloying strategy is reported to effectively boost the figure-of-merit (ZT) of Ge0.92Bi0.08Te-based alloys up to ≈2.2 at 723 K, attributed to a synergy of La-dopant induced band structuring and structural manipulation. Density-function-theory calculations reveal that La dopant enlarges the bandgap and converges the energy offset between the sub-valence bands in cubic-structured GeTe, leading to a significantly increased effective mass, which gives rise to a high Seebeck coefficient of ≈263 µV K−1 and in turn a superior power factor of ≈43 µW cm−1 K−2 at 723 K. Besides, comprehensive electron microscopy characterizations reveal that the multi-scale phonon scattering centers, including a high density of planar defects, Boron nanoparticles in tandem with enhanced boundaries, dispersive Ge nanoprecipitates in the matrix, and massive point defects, contribute to a low lattice thermal conductivity of ≈0.67 W m−1 K−1 at 723 K. Furthermore, a high microhardness of ≈194 Hv is witnessed in the as-designed Ge0.92Bi0.08Te(LaB6)0.04 alloy, derived from the multi-defect-induced strengthening. This work provides a strategy for developing high-performance and mechanical robust middle-temperature thermoelectric materials for practical thermoelectric applications.
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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: | 19 Jan 2022 02:46 |
| Last Modified: | 19 Jan 2022 03:21 |
| Uncontrolled Keywords: | electron microscopy; GeTe; LaB6; thermoelectric materials |
| Fields of Research (2008): | 09 Engineering > 0912 Materials Engineering > 091205 Functional Materials |
| Fields of Research (2020): | 40 ENGINEERING > 4016 Materials engineering > 401605 Functional materials |
| Identification Number or DOI: | https://doi.org/10.1002/smll.202105923 |
| URI: | http://eprints.usq.edu.au/id/eprint/45548 |
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