Realizing zT of 2.3 in Ge1−x−ySbxInyTe via reducing the phase-transition temperature and introducing resonant energy doping

Hong, Min and Chen, Zhi-Gang and Yang, Lei and Zou, Yi-Chao and Dargusch, Matthew and Wang, Hao and Zou, Jin (2018) Realizing zT of 2.3 in Ge1−x−ySbxInyTe via reducing the phase-transition temperature and introducing resonant energy doping. Advanced Materials, 30 (11 - Article 1705942). ISSN 0935-9648

Abstract

GeTe with rhombohedral-to-cubic phase transition is a promising lead-free thermoelectric candidate. Herein, theoretical studies reveal that cubic GeTe has superior thermoelectric behavior, which is linked to (1) the two valence bands to enhance the electronic transport coefficients and (2) stronger enharmonic phonon–phonon interactions to ensure a lower intrinsic thermal conductivity. Experimentally, based on Ge1−xSbxTe with optimized carrier concentration, a record-high figure-of-merit of 2.3 is achieved via further doping with In, which induces the distortion of the density of states near the Fermi level. Moreover, Sb and In codoping reduces the phase-transition temperature to extend the better thermoelectric behavior of cubic GeTe to low temperature. Additionally, electronic microscopy characterization demonstrates grain boundaries, a high-density of stacking faults, and nanoscale precipitates, which together with the inevitable point defects result in a dramatically decreased thermal conductivity. The fundamental investigation and experimental demonstration provide an important direction for the development of high-performance Pb-free thermoelectric materials.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version, in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - No Department
Date Deposited: 08 Feb 2019 04:31
Last Modified: 11 Feb 2019 04:34
Uncontrolled Keywords: density-functional-theory calculations, GeTe alloys, phase transition, phonon dynamics, thermoelectrics
Fields of Research : 03 Chemical Sciences > 0302 Inorganic Chemistry > 030206 Solid State Chemistry
10 Technology > 1007 Nanotechnology > 100708 Nanomaterials
09 Engineering > 0912 Materials Engineering > 091205 Functional Materials
02 Physical Sciences > 0204 Condensed Matter Physics > 020403 Condensed Matter Modelling and Density Functional Theory
Identification Number or DOI: 10.1002/adma.201705942
URI: http://eprints.usq.edu.au/id/eprint/35470

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