High figure of merit of Sb 2.18 Te 3 achieved via modulating stoichiometric ratio with chemical method
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High figure of merit of Sb2.18Te3 achieved via modulating stoichiometric ratio with chemical method Yiwei Zhao1,2 , Haiying Wang2, Hongyu Ma1, Xiang Yu1, Yong Liu1, Xingzhong Zhang1, Rui Xiong1,*, and Jing Shi1,* 1
Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China 2 School of Physics, Henan Normal University, Xinxiang 453002, China
Received: 19 August 2020
ABSTRACT
Accepted: 4 November 2020
Doping an element or more is widely used to regulate thermoelectric materials performance through adjusting electrical and thermal properties. In this work, a series of p-type Sb2(1?x)Te3 nanoflake composites are fabricated and tested. Excessive Sb in Sb2(1?x)Te3 causes high carrier density, which results in much larger electrical conductivity compared with that of pure Sb2Te3. The highest merit ZT of the Sb2.18Te3 composite reaches to 1.22 at 523 K, and the average ZT value in Sb2.18Te3 sample is above 1 obtained from 323 to 523 K, which is a decent ZT value at low–mid temperature zone for doped Sb2Te3-based composites. Self-doping element Sb into Sb2Te3 nanoflakes is an effective strategy that has a significant influence on improving power factor and keeping low thermal conductivity. Sb2(1?x)Te3 nanostructure composites are synthesized by reflux chemical method. Comparing with other methods involving solid solution melting, high-energy ball milling and solvothermal reaction, reflux chemical reaction method is not only a more facile, timesaving and green way to produce nanoscale materials but also can be applied to mass production.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Recently, thermoelectric (TE) materials have attracted extensive interest because they can directly convert heat and electricity without discharging pollutant and noisy [1]. TE devices are widely used in waste heat recovery to generate electricity as well as electronic cooling. The larger TE conversion efficiency
requires a higher ZT value. TE conversion efficiency can be estimated by the dimensionless figure of merit (ZT), defined as ZT ¼ ððS2 rÞTÞj; where S, r, T and j are defined as Seebeck coefficient, electrical conductivity, absolute temperature and total thermal conductivity, respectively [2]. Some Bi2Te3 and derivatives with high ZT value have already applied in commercial production [3]. According to ZT
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https://doi.org/10.1007/s10854-020-04834-1
J Mater Sci: Mater Electron
equation, a high ZT contains a low thermal conductivity with fine electrical transport properties. However, many difficulties hinder the improvement of ZT because the three coefficients (S, r and j) are interrelated due to carrier concentration. In the several tens of years, there have been many tactics applied to enhance the thermoelectric properties through optimizing electrical transport conductivity or reducing thermal conductivity. Many methods ha
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