Unequal bonding in Ag-CuIn3Se5-based solid solutions responsible for reduction in lattice thermal conductivity and improvement in thermoelectric performance

Jiaolin Cui; Yufu Lu; Shaoping Chen; Xianglian Liu; Zhengliang Du

doi:10.1039/c8ra00316e

Unequal bonding in Ag-CuIn₃Se₅-based solid solutions responsible for reduction in lattice thermal conductivity and improvement in thermoelectric performance

RSC Adv. 2018 Mar 5;8(17):9574-9579. doi: 10.1039/c8ra00316e. eCollection 2018 Feb 28.

Authors

Jiaolin Cui¹, Yufu Lu^{1

2}, Shaoping Chen², Xianglian Liu¹, Zhengliang Du¹

Affiliations

¹ School of Materials & Engineering, Ningbo University of Technology Ningbo 315016 China cuijiaolin@163.com.
² Materials Science and Engineering College, Taiyuan University of Technology Taiyuan 030024 China.

Abstract

Owing to their unique crystal and band structures, in thermoelectrics increasing attention has recently been paid to compounds of the ternary I-III-VI chalcopyrite family. In this work, unequal bonding between cation and anion pairs in Cu_1-y Ag _y In₃Se_4.9Te_0.1 solid solutions, which can be effectively used to disturb phonon transport, has been proposed. The unequal bonding, which is represented by the difference of bond lengths Δd, Δd = d _(Cu-Se) - d _(In-Se) and anion position displacement from its equilibrium position Δu = u - 0.25, is created by the isoelectronic substitution of Ag for Cu. At y = 0.2 both the Δd and Δu values reach their maxima, resulting in a remarkable reduction in lattice thermal conductivity (κ _L) and an improvement in TE performance. However, as the y value increase to 0.3 both Δd and Δu values decrease, causing the κ _L value to increase and the ZT value to decrease from 0.5 to 0.24 at 930 K. Accordingly, unequal bonding might be an alternative way to improve the TE performance of ternary chalcopyrites.