Direct observation of one-dimensional disordered diffusion channel in a chain-like thermoelectric with ultralow thermal conductivity

Jiawei Zhang,Bo B Iversen,Seiya Takahashi,Kasper Tolborg,Lirong Song,Martin Bondesgaard,Nikolaj Roth,Eiji Nishibori

doi:10.1038/s41467-021-27007-y

Jiawei Zhang, Bo B Iversen + Show 6 more

Open Access

https://doi.org/10.1038/s41467-021-27007-y

Copy DOI

Journal: Nature Communications	Publication Date: Nov 18, 2021
Citations: 27	License type: open-access

Affiliation: Aarhus University, University of Tsukuba

Abstract

Structural disorder, highly effective in reducing thermal conductivity, is important in technological applications such as thermal barrier coatings and thermoelectrics. In particular, interstitial, disordered, diffusive atoms are common in complex crystal structures with ultralow thermal conductivity, but are rarely found in simple crystalline solids. Combining single-crystal synchrotron X-ray diffraction, the maximum entropy method, diffuse scattering, and theoretical calculations, here we report the direct observation of one-dimensional disordered In1+ chains in a simple chain-like thermoelectric InTe, which contains a significant In1+ vacancy along with interstitial indium sites. Intriguingly, the disordered In1+ chains undergo a static-dynamic transition with increasing temperature to form a one-dimensional diffusion channel, which is attributed to a low In1+-ion migration energy barrier along the c direction, a general feature in many other TlSe-type compounds. Our work provides a basis towards understanding ultralow thermal conductivity with weak temperature dependence in TlSe-type chain-like materials.

Highlights

Structural disorder, highly effective in reducing thermal conductivity, is important in technological applications such as thermal barrier coatings and thermoelectrics
Ultralow thermal conductivity is common in large complex crystal structures, whereas it is rare in simple crystal structures
Interstitial, disordered atomic positions are commonly observed in large complex crystal structures such as Zn4Sb35 and oxide-ion conductors[30], whereas they are rarely found in small simple crystal structures

Summary

Introduction

Structural disorder, highly effective in reducing thermal conductivity, is important in technological applications such as thermal barrier coatings and thermoelectrics. Combining single-crystal synchrotron X-ray diffraction, the maximum entropy method, diffuse scattering, and theoretical calculations, here we report the direct observation of one-dimensional disordered In1+ chains in a simple chain-like thermoelectric InTe, which contains a significant In1+ vacancy along with interstitial indium sites. The MEM electron density at elevated temperatures and ab initio molecular dynamics simulations clearly show a static-dynamic transition of interstitial, disordered In1+ ions, suggesting a 1D In1+-ion diffusion/hopping pathway We attribute such a diffusion pathway to a very low In1+-ion migration energy barrier along the c direction, which is found to be a general feature in many other TlSe-type compounds. The direct visualization of a 1D disordered diffusion channel accounts for the reported superionic conductivity and provides a basis for understanding ultralow thermal conductivity and its peculiar, weak temperature dependence in InTe and other TlSe-type compounds

Methods

Results

Conclusion