Illustration of a simple crystal structure

Thermal conductivity at its lower limit

30 June 2024

A team of researchers from the Department of Mechanical Engineering at the University of Hong Kong has made significant progress in the field of thermal transport in crystals. The team, led by Dr Yue Chen, focused on a simple crystal structure material, AgTlI2, which surprisingly exhibited an ultralow thermal conductivity of 0.25 W/mK at room temperature.

Through advanced experimental techniques and simulations, the research team uncovered the unique thermal transport mechanisms of AgTlI2, revealing a blend of ultralow particle-like and wavelike phonon thermal transports. This discovery not only emphasises the potential of simple crystal structures in achieving low thermal conductivity but also points the way towards additional research to expand the range of materials with suppressed thermal transport.

The interdisciplinary study involved collaboration with colleagues at Bohai University, Normandie University, and the Institute Jean Lamour in France and combined expertise in sample preparation, X-ray scattering, thermal conductivity measurement, and simulations. The team's findings have been published in Nature Communications, with Dr Zezhu Zeng as the first author. This research opens new avenues for investigating materials with ultralow thermal conductivity, offering promising prospects for advancements in thermal insulation and thermoelectrics.

Yue Chen was the recipient of a grant from Croucher Foundation in 2019 as part of its support for conferences and workshops in Hong Kong.