Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn1 − xSe via anisotropy and vacancy synergy
Article
Article Title | Optimization of sodium hydroxide for securing high thermoelectric performance in polycrystalline Sn1 − xSe via anisotropy and vacancy synergy |
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ERA Journal ID | 212807 |
Article Category | Article |
Authors | Shi, Xiao-Lei (Author), Liu, Wei-Di (Author), Wu, Ang-Yin (Author), Nguyen, Van T. (Author), Gao, Han (Author), Sun, Qiang (Author), Moshwan, Raza (Author), Zou, Jin (Author) and Chen, Zhi-Gang (Author) |
Journal Title | InfoMat |
Journal Citation | 2 (6), pp. 1201-1215 |
Number of Pages | 15 |
Year | 2020 |
Publisher | Wiley-VCH Verlag GmbH & Co. KGaA |
Place of Publication | Germany |
ISSN | 2567-3165 |
Digital Object Identifier (DOI) | https://doi.org/10.1002/inf2.12057 |
Web Address (URL) | https://onlinelibrary.wiley.com/doi/10.1002/inf2.12057 |
Abstract | The morphology and composition are two key factors to determine the thermoelectric performance of aqueously synthesized tin selenide (SnSe) crystals; however, their controlling is still under exploring. In this study, we report a high figure‐of‐merit (ZT) of ∼1.5 at 823 K in p‐type polycrystalline Sn1 − xSe resulted from a synergy of morphology control and vacancy optimization, realized by carefully tuning the sodium hydroxide (NaOH) concentration during solvothermal synthesis. After a comprehensive investigation on various NaOH concentrations, it was found that an optimized NaOH amount of 10 mL with a concentration of 10 mol L−1 can simultaneously achieve a large average crystal size and a high Sn vacancy concentration of ∼2.5%. The large microplate‐like crystals lead to a considerable anisotropy in the sintered pellets, and the high Sn vacancy level contributes to an optimum hole concentration to the level of ∼2.3 × 1019 cm−3, and in turn a high power factor of ∼7.4 μW cm−1 K−2 at 823 K, measured along the direction perpendicular to the sintering pressure. In addition, a low thermal conductivity of ∼0.41 W m−1 K−1 is achieved by effective phonon scattering at localized crystal imperfections including lattice distortions, grain boundaries, and vacancy domains, as observed by detailed structural characterizations. Furthermore, a competitive compressive strength of ∼52.1 MPa can be achieved along the direction of high thermoelectric performance, indicating a mechanically robust feature. This study provides a new avenue in achieving high thermoelectric performance in SnSe‐based thermoelectric materials. |
Keywords | anisotropy, sodium hydroxide, thermoelectric, tin selenide, vacancy |
ANZSRC Field of Research 2020 | 401605. Functional materials |
Byline Affiliations | Centre for Future Materials |
University of Queensland | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q595x/optimization-of-sodium-hydroxide-for-securing-high-thermoelectric-performance-in-polycrystalline-sn1-xse-via-anisotropy-and-vacancy-synergy
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