Elastic heterogeneity, vibrational states, and thermal conductivity across an amorphisation transition

TL;DR

This study uses molecular dynamics to explore how elastic heterogeneity in disordered solids influences vibrational states and thermal conductivity during amorphisation, revealing strong correlations among these properties.

Contribution

It introduces a controlled simulation approach to link elastic heterogeneity with vibrational and thermal anomalies during amorphisation.

Findings

Elastic heterogeneity increases with disorder

Vibrational states are altered by elastic heterogeneity

Thermal conductivity decreases as disorder progresses

Abstract

Disordered solids exhibit unusual properties of their vibrational states and thermal conductivities. Recent progresses have well established the concept of "elastic heterogeneity", i.e., disordered materials show spatially inhomogeneous elastic moduli. In this study, by using molecular-dynamics simulations, we gradually introduce "disorder" into a numerical system to control its modulus heterogeneity. The system starts from a perfect crystalline state, progressively transforms into an increasingly disordered crystalline state, and finally undergoes structural amorphisation. We monitor independently the elastic heterogeneity, the vibrational states, and the thermal conductivity across this transition, and show that the heterogeneity in elastic moduli is well correlated to vibrational and thermal anomalies of the disordered system.