A generalized Debye-Peierls/Allen-Feldman model for the lattice thermal conductivity of low dimensional and disordered materials

TL;DR

This paper introduces a comprehensive model that extends existing theories to predict the lattice thermal conductivity of low-dimensional and disordered materials, aligning well with experimental and simulation data.

Contribution

It provides a novel, generalized framework that incorporates low-D effects and phonon localization, improving understanding of thermal transport in complex materials.

Findings

Good agreement with experimental data

Captures unique thermal transport features in low-D systems

Highlights the reduced role of diffusons in disordered materials

Abstract

We present a generalized model to describe the lattice thermal conductivity of low-dimensional (low-D) and disordered systems. The model is a straightforward generalization of the Debye-Peierls and Allen-Feldman schemes to arbitrary dimensions, accounting for low-D effects such as differences in dispersion, density of states, and scattering. Similar in spirit to the Allen-Feldman approach, heat carriers are categorized according to their transporting capacity as propagons, diffusons, and locons. The results of the generalized model are compared to experimental results when available, and equilibrium molecular dynamics simulations otherwise. The results are in very good agreement with our analysis of phonon localization in disordered low-D systems, such as amorphous graphene and glassy diamond nanothreads. Several unique aspects of thermal transport in low-D and disordered systems, such as milder suppression of thermal conductivity and negligble diffuson contributions, are captured by the approach.