Retarding Ostwald ripening through Gibbs adsorption and interfacial complexions leads to high-performance SnTe thermoelectrics

Decheng An; Jiangjing Wang; Jie Zhang; Xin Zhai; Zepeng Kang; Wenhao Fan; Jian Yan; Yequn Liu; Lu Lu; Chun-Lin Jia; Matthias Wuttig; Oana Cojocaru-Mirédin; Shaoping Chen; Wenxian Wang; G. Jeffrey Snyder; Yuan Yu

doi:10.1039/D1EE01977E

Retarding Ostwald ripening through Gibbs adsorption and interfacial complexions leads to high-performance SnTe thermoelectrics†

Decheng An,

‡^a Jiangjing Wang,‡^bc Jie Zhang,^a Xin Zhai,^a Zepeng Kang,^d Wenhao Fan,^d Jian Yan,

^e Yequn Liu,^f Lu Lu,^g Chun-Lin Jia,^g Matthias Wuttig,

^b Oana Cojocaru-Mirédin,^b Shaoping Chen,*^a Wenxian Wang,*^a G. Jeffrey Snyder

^h and Yuan Yu

*^b

Author affiliations

* Corresponding authors

^a College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China
E-mail: sxchenshaoping@163.com, wangwenxian@tyut.edu.cn

^b Institute of Physics IA, RWTH Aachen University, 52056 Aachen, Germany
E-mail: yu@physik.rwth-aachen.de

^c Center for Alloy Innovation and Design, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China

^d College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024, China

^e School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China

^f Analytical Instrumentation Center, State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China

^g School of Microelectronics, State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China

^h Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA

Abstract

Nanoprecipitation is a routine method to decrease the thermal conductivity for advancing thermoelectric performance. However, the coarsening/Ostwald ripening of precipitates under temperature gradients in long-duration service deteriorates the efficacy of this strategy. Enlightened by the Gibbs adsorption-induced suppression of Ostwald ripening, we designed a highly stable thermoelectric system SnAg_0.05Te-x%CdSe with embedded novel core/shell nanoprecipitates. Scanning transmission electron microscopy and atom probe tomography reveal that the precipitate core is CdTe and the shell is formed by Ag segregation with structures and compositions different from its abutting phases, termed interfacial complexions. This complexions layer suppresses the coarsening of precipitates by decreasing the interfacial Gibbs free energy, resulting in a high number of nanoscale precipitates. The enlarged phonon scattering cross-section of nanoprecipitates enabled by Gibbs adsorption along with interfacial complexions restrains the lattice thermal conductivity to its minimum while maintaining high carrier mobility. This eventually leads to an outstanding figure-of-merit (zT) of 1.5 at 873 K in thermally aged SnAg_0.05Te-6%CdSe, assisted with valence band flattening and convergence. This work explores the mechanisms underpinning precipitate stabilization and provides a new paradigm to design nanostructured thermoelectrics.

Energy & Environmental Science

Retarding Ostwald ripening through Gibbs adsorption and interfacial complexions leads to high-performance SnTe thermoelectrics†

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Retarding Ostwald ripening through Gibbs adsorption and interfacial complexions leads to high-performance SnTe thermoelectrics

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