Integration of multi-scale defects for optimizing thermoelectric properties of n-type Cu1-xCdxFeS2 (x = 0-0.1)

Bangzhi Ge; Jiabin Hu; Zhongqi Shi; Hailong Wang; Hongyan Xia; Guanjun Qiao

doi:10.1039/c9nr04693c

Integration of multi-scale defects for optimizing thermoelectric properties of n-type Cu_1-xCd_xFeS₂ (x = 0-0.1)

Nanoscale. 2019 Oct 7;11(37):17340-17349. doi: 10.1039/c9nr04693c. Epub 2019 Sep 13.

Authors

Bangzhi Ge¹, Jiabin Hu¹, Zhongqi Shi¹, Hailong Wang², Hongyan Xia¹, Guanjun Qiao³

Affiliations

¹ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China. zhongqishi@mail.xjtu.edu.cn.
² Advanced Energy Storage Materials and Devices Lab, School of Physics and Electronic-Electrical Engineering, Ningxia University, Yinchuan, 750021, China.
³ State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China. zhongqishi@mail.xjtu.edu.cn and School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, China.

PMID: 31517377
DOI: 10.1039/c9nr04693c

Abstract

The performance of thermoelectric (TE) materials is strongly influenced by multi-scale defects. Some defects can improve the TE performance but some are unfavorable. Therefore, the multi-scale defects need to be integrated rationally to enhance the TE properties. Here, the defects including atomic-scale point defects, high-density grain boundaries and nano-precipitates were integrated into CuFeS₂, an n-type and Earth-abundant TE material. Primitively, a Cd dopant with high scattering factor was introduced to form point defects in Cu_1-xCd_xFeS₂ (x = 0-0.1) according to the calculated scattering parameters. Furthermore, the processes of quenching, annealing, high-energy ball milling (QAH) and sintering were carried out to integrate the multi-scale defects into Cu_1-xCd_xFeS₂. The results suggested that point defects and antisite defects were achieved and the unfavorable Cd'_Fe defects were suppressed effectively, leading to a higher electrical conductivity. Moreover, the CdS nano-precipitates played a vital role in carrier filtering to increase the Seebeck coefficient. Meanwhile, the high-density grain boundaries suppressed the lattice thermal conductivity. As a result, a peak ZT value of 0.39 at 723 K was obtained in Cu_0.92Cd_0.08FeS₂, which is the highest value reported so far in the CuFeS₂ family.