Toward phonon-boundary engineering in nanoporous materials

TL;DR

This paper investigates how pore shape and arrangement in nanoporous materials influence thermal conductivity, demonstrating a configuration that reduces it by over 60%, aiding thermoelectric material development.

Contribution

It introduces a phonon mean free path dependent model to optimize pore arrangements for minimal thermal conductivity in nanoporous materials.

Findings

Periodic misaligned triangular pores reduce thermal conductivity by over 60%.

Pore-pore distance critically affects thermal transport suppression.

Optimal pore arrangement significantly enhances thermoelectric efficiency.

Abstract

Tuning thermal transport in nanostructured materials is a powerful approach to develop high-efficiency thermoelectric materials. Using a recently developed approach based on the phonon mean free path dependent Boltzmann transport equation, we compute the effective thermal conductivity of nanoporous materials with pores of various shapes and arrangements. We assess the importance of pore-pore distance in suppressing thermal transport, and identify the pore arrangement that minimizes the thermal conductivity, composed of a periodic arrangement of two misaligned rows of triangular pores. Such a configuration yields a reduction in the thermal conductivity of more than $60 \%$ with respect the simple circular aligned case with the same porosity.