Four-phonon breakthrough overcomes thermal-conductivity conundrum

Researchers believe they can predict four-phonon scattering, an advance in quantum mechanical science that could have an impact in applications that include electronics cooling.

Phonons are quantum-mechanical phenomena that describe how vibrations travel through a material's crystal structure. The phonons interact, sometimes combining and splitting into new phonons, changing direction and behaviour.

This “scattering” is fundamental to how a material conducts heat. Until now, researchers have been able to realistically model only the interactions of three phonons. In new findings, researchers from Purdue University and Oak Ridge National Laboratory have shown how to accurately model the interactions of four phonons and their effect on heat flow.

The discovery could help efforts to improve a range of technologies including thermoelectric devices; thermal-barrier coatings; heat sinks for electronics cooling; nuclear fuels; and research into solid-state heat transfer in general.

“Being able to predict four-phonon scattering has been a decades-long challenge,” said Xiulin Ruan, a Purdue professor of mechanical engineering.