Dynamic disorder phonon scattering mediated by Cu atomic hopping and diffusion in Cu3SbSe3

Chen Wang,Yue Chen,Yanzhong Pei,Yixuan Wu

doi:10.1038/s41524-020-00421-4

Chen Wang, Yue Chen + Show 2 more

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https://doi.org/10.1038/s41524-020-00421-4

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Abstract

Cu3SbSe3 that exhibits distinct liquid-like sublattice due to the heterogeneous bonding environment has emerged as a promising low cost superionic semiconductor with intrinsic ultralow thermal conductivity. However, the relationship between atomic dynamics resulting in liquid-like diffusion and anomalous phonon transport properties remains poorly understood. Herein, combing ab initio molecular dynamics with temperature-dependent Raman measurements, we have performed a thorough investigation on the lattice dynamics of Cu3SbSe3. Superionic transition is unveiled for both structurally inequivalent Cu atoms at elevated temperatures, while the Se-formed tetrahedral framework can simultaneously maintain. An intermediate state of Cu3SbSe3 through the mixture of quasi-1D/2D Cu nearest-neighbor vacancy hopping is discovered below the superionic transition temperature. Our results also manifest that phonons predominately involved with Cu contributions along diffusion channels have been strongly scattered during the superionic transition, whereas the liquid-like diffusion of Cu is too slow to completely breakdown the propagation of all transverse phonon modes. The insight provided by this work into the atomic dynamics and phonon scattering relationship may pave the way for further phonon engineering of Cu3SbSe3 and related superionic materials.

Highlights

Thermal conduction inside condensed system can be considered as internal energy transfer through microscopic collisions of particles and the capability to support propagation of transverse modes often serves as a fundamental criterion to dynamically distinguish solid from liquid[1,2]
As the thermoelectric conversion efficiency is inversely proportional to thermal conductivity, a desired strategy to achieve advancements in thermoelectrics follows the recent paradigm of phonon-liquid electron-crystal (PLEC)[9], which evolves from phonon-glass electron-crystal[10], and formulates that the decoupled lattice thermal conductivity can be decreased even below glasses because the propagation of transverse phonons are suppressed by the liquid-like fluctuating sublattice
Warming acropssffiffi 400 K, Δ(r)Cu1 and Δ(r)Cu2 increase approximately linearly with t and exhibit distinct disorder effect and continuous liquid-like diffusion, which is consistent with previous temperature-dependent atomic dynamics studies[15,21] and high temperature X-ray diffraction experiment[27,28] for Cu3SbSe3

Summary

Introduction

Thermal conduction inside condensed system can be considered as internal energy transfer through microscopic collisions of particles and the capability to support propagation of transverse modes often serves as a fundamental criterion to dynamically distinguish solid from liquid[1,2]. Superionic conductors that exhibit long-range liquid-like ionic behavior while simultaneously maintaining solid crystalline sublattice for electronic conduction, have emerged as a class of promising candidate to realize intrinsic ultralow thermal conductivity and represent potential PLEC materials[11,12,13]. A comprehensive study of the relation between the atomic dynamics and the corresponding anharmonic phonon properties at elevated temperatures is fundamental to understand the phonon scattering evolution across the superionic transition

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