Issue 48, 2020

Manipulating the phase transformation temperature to achieve cubic Cu5FeS4−xSex and enhanced thermoelectric performance

Abstract

Cu5FeS4, one of the promising Earth-abundant and low-toxicity Cu-based thermoelectric materials, transforms from an orthorhombic structure to a cubic phase when heated, which may impede its applications at elevated temperatures. Herein, we demonstrate that the phase transformation temperature of Cu5FeS4 can be suppressed to lower temperatures by replacing S by Se, as demonstrated in a series of Cu5FeS4−xSex (x = 0, 0.4, 0.8, 1.5, 2.0) compounds. Upon increasing the Se content x from 0 to 2.0, the phase transformation of Cu5FeS4−xSex takes place at progressively lower temperatures, with Cu5FeS2Se2 having a high cubic structure at room temperature. The Se-substituted Cu5FeS4 compounds achieve tremendously improved electrical performance, which is consistent with the calculated higher transport coefficient and weighted mobility. Combined with the still low lattice thermal conductivity, the Se-substituted Cu5FeS4 compounds achieve improved zT, for example, an improved peak zT of ∼0.6 at 735 K in Cu5FeS3.6Se0.4, and an average zT of ∼0.42 from 300 to 735 K in Cu5FeS2.5Se1.5 that is about 130% higher than that of Cu5FeS4. This study sheds light on enhancement of the thermoelectric performance of Cu5FeS4 based materials via manipulation of their phase transformation temperature.

Graphical abstract: Manipulating the phase transformation temperature to achieve cubic Cu5FeS4−xSex and enhanced thermoelectric performance

Supplementary files

Article information

Article type
Paper
Submitted
02 Sept. 2020
Accepted
02 Nov. 2020
First published
04 Nov. 2020

J. Mater. Chem. C, 2020,8, 17222-17228

Manipulating the phase transformation temperature to achieve cubic Cu5FeS4−xSex and enhanced thermoelectric performance

L. Guo, B. Zhang, H. Zhu, H. Wu, Y. Yan, X. Gong, X. Lu, G. Han, G. Wang and X. Zhou, J. Mater. Chem. C, 2020, 8, 17222 DOI: 10.1039/D0TC04179C

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