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Cu1.8S has been considered as a potential thermoelectric (TE) material for its stable electrical and thermal properties, environmental benignity, and low cost. Herein, the TE properties of nanostructured Cu1.8S1-xTex (0 ≤ x ≤ 0.2) bulks fabricated by a facile process combining mechanical alloying (MA) and room-temperature high-pressure sintering (RT-HPS) technique were optimized via eliminating the volatilization of S element and suppressing grain growth. Experimentally, a single phase of Cu1.8S was obtained at x = 0, and a second Cu1.96S phase formed in all Cu1.8S1-xTex samples when 0.05 ≤ x ≤ 0.125. With further increasing x to 0.15 ≤ x ≤ 0.2, the Cu2-zTe phase was detected and the samples consisted of Cu1.8S, Cu1.96S, and Cu2-zTe phases. Benefiting from a modified band structure and the coexisted phases of Cu1.96S and Cu2-zTe, the power factor is enhanced in all Cu1.8S1-xTex (0.05 ≤ x ≤ 0.2) alloys. Combining with a drastic decrease in the thermal conductivity due to the strengthened phonon scatterings from multiscale defects introduced by Te doping and nano-grain boundaries, a maximum figure of merit (ZT) of 0.352 is reached at 623 K for Cu1.8S0.875Te0.125, which is 171% higher than that of Cu1.8S (0.130). The study demonstrates that doping Te is an effective strategy to improve the TE performance of Cu1.8S based materials and the proposed facile method combing MA and RT-HPS is a potential way to fabricate nanostructured bulks.


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Optimal performance of Cu1.8S1-xTex thermoelectric materials fabricated via high-pressure process at room temperature

Show Author's information Rui ZHANGJun PEI( )Zhi-Jia HANYin WUZhao ZHAOBo-Ping ZHANG( )
Beijing Municipal Key Laboratory of New Energy Materials and Technologies, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China

Abstract

Cu1.8S has been considered as a potential thermoelectric (TE) material for its stable electrical and thermal properties, environmental benignity, and low cost. Herein, the TE properties of nanostructured Cu1.8S1-xTex (0 ≤ x ≤ 0.2) bulks fabricated by a facile process combining mechanical alloying (MA) and room-temperature high-pressure sintering (RT-HPS) technique were optimized via eliminating the volatilization of S element and suppressing grain growth. Experimentally, a single phase of Cu1.8S was obtained at x = 0, and a second Cu1.96S phase formed in all Cu1.8S1-xTex samples when 0.05 ≤ x ≤ 0.125. With further increasing x to 0.15 ≤ x ≤ 0.2, the Cu2-zTe phase was detected and the samples consisted of Cu1.8S, Cu1.96S, and Cu2-zTe phases. Benefiting from a modified band structure and the coexisted phases of Cu1.96S and Cu2-zTe, the power factor is enhanced in all Cu1.8S1-xTex (0.05 ≤ x ≤ 0.2) alloys. Combining with a drastic decrease in the thermal conductivity due to the strengthened phonon scatterings from multiscale defects introduced by Te doping and nano-grain boundaries, a maximum figure of merit (ZT) of 0.352 is reached at 623 K for Cu1.8S0.875Te0.125, which is 171% higher than that of Cu1.8S (0.130). The study demonstrates that doping Te is an effective strategy to improve the TE performance of Cu1.8S based materials and the proposed facile method combing MA and RT-HPS is a potential way to fabricate nanostructured bulks.

Keywords:

Cu1.8S, Te doping, nanostructure, high pressure, thermoelectric (TE)
Received: 07 February 2020 Revised: 28 April 2020 Accepted: 08 May 2020 Published: 09 July 2020 Issue date: October 2020
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Publication history
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Publication history

Received: 07 February 2020
Revised: 28 April 2020
Accepted: 08 May 2020
Published: 09 July 2020
Issue date: October 2020

Copyright

© The author(s) 2020

Acknowledgements

This study was supported by the National Key R&D Program of China (Grant No. 2018YFB0703600) and the National Natural Science Foundation of China (Grant No. 11474176).

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