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Title: Tailoring the phase transition temperature to achieve high-performance cubic GeTe-based thermoelectrics
Authors: Ady Suwardi
Cao, Jing
Hu, Lei
Wei, Fengxia
Wu, Jing
Zhao, Yunshan
Lim, Su Hui
Yang, Lan
Tan, Xian Yi
Chien, Sheau Wei
Yin, Yan
Zhou, Wu-Xing
Wong, Nancy Lai Mun
Wang, Xizu
Lim, Suo Hon
Ni, Xiping
Li, Dengfeng
Yan, Qingyu
Zheng, Yun
Zhang, Gang
Xu, Jianwei
Keywords: Engineering::Materials::Energy materials
Issue Date: 2020
Source: Ady Suwardi, Cao, J., Hu, L., Wei, F., Wu, J., Zhao, Y., Lim, S. H., Yang, L., Tan, X. Y., Chien, S. W., Yin, Y., Zhou, W., Wong, N. L. M., Wang, X., Lim, S. H., Ni, X., Li, D., Yan, Q., Zheng, Y., ...Xu, J. (2020). Tailoring the phase transition temperature to achieve high-performance cubic GeTe-based thermoelectrics. Journal of Materials Chemistry A, 8, 18880-18890.
Journal: Journal of Materials Chemistry A
Abstract: GeTe is highly sought-after due to its versatility as high-performance thermoelectrics, phase change materials, as well as ferroelectric Rashba semiconductor. Compared to most thermoelectric materials, it has an additional degree of freedom of rhombohedral-cubic phase transition at 673 K. At this temperature, the lattice thermal conductivity approaches theoretical minimum due to ferroelectric instability while the high-energy Σ and low-energy L bands converge to give outstanding electronic properties. Therefore, modulation of the phase transition temperature allows simultaneous and synergistic tuning of electronic and thermal transport properties to achieve high zT. In this work, Sn alloying together with Bi, Sb doping is used to suppress the phase transition to achieve a pure cubic structure with lattice thermal conductivity of around 0.4 W/mK and peak zT of 1.7 at 723 K with average zT of 1.23 between 400 and 800 K. Furthermore, Vickers hardness of 270, and Young’s modulus of 63.5 GPa in Ge0.4Sn0.4Bi0.02Sb0.12Te is by far the highest amongst binary chalcogenides. More importantly, the high quality factor achieved in this work enables ample room for further zT improvements. The fundamental insights drawn from this work provide a pathway towards engineering GeTe-based alloys to achieve high zT at any temperature of interest.
ISSN: 2050-7488
DOI: 10.1039/D0TA06013E
Rights: © 2020 Royal Society of Chemistry. All rights reserved. This paper was published in Journal of Materials Chemistry A and is made available with permission of Royal Society of Chemistry
Fulltext Permission: open
Fulltext Availability: With Fulltext
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