Issue 24, 2016

High thermoelectric performance of superionic argyrodite compound Ag8SnSe6

Abstract

A good thermoelectric material usually has a high power factor and low thermal conductivity for high figure of merit (ZT), and is also environmentally friendly and economical. Superionic compounds are heavily studied because of their ultra-low thermal conductivity even though the thermal stability remains an issue. In this work, we report a superionic argyrodite compound Ag8SnSe6 as a promising mid-temperature thermoelectric material because of its high ZT and good thermal stability up to 550 °C. It is revealed that Ag8SnSe6 exhibits a decent Seebeck coefficient (n-type) and electrical conductivity. At the same time, its thermal conductivity is lower than the glass limit with the thermal capacity CV below 3NkB at high temperature, where N is the Avogadro's number and kB the Boltzmann constant. Detailed microstructural and thermodynamic characterization of this compound is performed to understand the electronic and phononic origins of the thermoelectric properties. The highly random ionic occupations in the cubic phase, leading to the molten silver sublattice and phononic mode softening, are responsible for the very low thermal conductivity and ZT ∼ 1.1 at 450 °C.

Graphical abstract: High thermoelectric performance of superionic argyrodite compound Ag8SnSe6

Supplementary files

Article information

Article type
Paper
Submitted
25 Feb 2016
Accepted
16 May 2016
First published
17 May 2016

J. Mater. Chem. C, 2016,4, 5806-5813

High thermoelectric performance of superionic argyrodite compound Ag8SnSe6

L. Li, Y. Liu, J. Dai, A. Hong, M. Zeng, Z. Yan, J. Xu, D. Zhang, D. Shan, S. Liu, Z. Ren and J. Liu, J. Mater. Chem. C, 2016, 4, 5806 DOI: 10.1039/C6TC00810K

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