Achieving High-Performance Ge0.92Bi0.08Te Thermoelectrics via LaB6-Alloying-Induced Band Engineering and Multi-Scale Structure Manipulation

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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