Thermal Conductivity of BAs under Pressure

TL;DR

This study measures the thermal conductivity of boron arsenide (BAs) under pressures up to 30 GPa, revealing an unusual pressure-independent behavior that challenges typical expectations for nonmetallic crystals and highlights the role of phonon dispersion.

Contribution

It provides experimental data on BAs thermal conductivity under pressure, testing first principles theories of phonon scattering and dispersion effects.

Findings

Thermal conductivity of BAs remains constant up to 30 GPa.

Contrasts with typical increase in nonmetallic crystals under pressure.

Highlights the link between phonon dispersion and scattering rates.

Abstract

The thermal conductivity of boron arsenide (BAs) is believed to be influenced by phonon scattering selection rules due to its special phonon dispersion. Compression of BAs leads to significant changes in phonon dispersion, which allows for a test of first principles theories for how phonon dispersion affects three- and four-phonon scattering rates. This study reports the thermal conductivity of BAs from 0 to 30 GPa. Thermal conductivity vs. pressure of BAs is measured by time-domain thermoreflectance with a diamond anvil cell. In stark contrast to what is typical for nonmetallic crystals, BAs is observed to have a pressure independent thermal conductivity below 30 GPa. The thermal conductivity of nonmetallic crystals typically increases upon compression. The unusual pressure independence of thermal conductivity of BAs shows the important relationship between phonon dispersion properties and three- and four-phonon scattering rates.