Synergistic optimization of thermoelectric performance of Sb doped GeTe with a strained domain and domain boundaries

In addition to the Ge-vacancy control of GeTe, the antimony (Sb) substitution of GeTe for the improvement of thermoelectric performance is explored for Ge 1−x Sb x Te with x = 0.08–0.12. The concomitant carrier concentration ( n ) and the aliovalent Sb ion substitution led to an optimal doping level...

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Bibliographic Details
Published in:Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-03, Vol.8 (10), p.5332-5341
Main Authors: Bayikadi, Khasim Saheb, Wu, Chien Ting, Chen, Li-Chyong, Chen, Kuei-Hsien, Chou, Fang-Cheng, Sankar, Raman
Format: Article
Language:English
Subjects:
Antimony
Boundaries
Carrier density
Domains
Frequency ranges
Heat conductivity
Heat transfer
Lattice vacancies
Optimization
Phonons
Power factor
Room temperature
Strain analysis
Substitutes
Thermal conductivity
Thermoelectricity
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Summary:In addition to the Ge-vacancy control of GeTe, the antimony (Sb) substitution of GeTe for the improvement of thermoelectric performance is explored for Ge 1−x Sb x Te with x = 0.08–0.12. The concomitant carrier concentration ( n ) and the aliovalent Sb ion substitution led to an optimal doping level of x = 0.10 to show ZT ∼ 2.35 near ∼800 K, which is significantly higher than those single- and multi-element substitution studies of the GeTe system reported in the literature. In addition, Ge 0.9 Sb 0.1 Te demonstrates an impressively high power factor of ∼36 μW cm −1 K −2 and a low thermal conductivity of ∼1.1 W m −1 K −1 at 800 K. The enhanced ZT level for Ge 0.9 Sb 0.1 Te is explained through a systematic investigation of micro-structural change and strain analysis from room temperature to 800 K. A significant reduction of lattice thermal conductivity ( κ lat ) is identified and explained by the Sb substitution-introduced strained and widened domain boundaries for the herringbone domain structure of Ge 0.9 Sb 0.1 Te. The Sb substitution created multiple forms of strain near the defect centre, the herringbone domain structure, and widened tensile/compressive domain boundaries to support phonon scattering that covers a wide frequency range of the phonon spectrum to reduce lattice thermal conductivity effectively.
ISSN:2050-7488
2050-7496
DOI:10.1039/D0TA00628A