Researchers Uncover Mechanism Behind Low Thermal Conductivity

Researchers from the Queensland University of Technology (QUT) have made significant strides in understanding why certain materials exhibit exceptionally low thermal conductivity. This discovery, published in Nature Communications, could have far-reaching implications for energy conversion, insulation, and gas storage technologies.

The QUT team identified a structural mechanism that explains why materials with uneven compositions can effectively block heat. The first author, Siqi Liu, highlighted that these findings challenge traditional models that often overlook the importance of microstructural features in thermal conductivity.

Challenging Conventional Models

Liu explained, “People used to think low thermal conductivity in uneven materials was just due to how the different parts were mixed.” The research revealed that the true reason lies in tiny defects known as edge dislocations, which scatter heat more effectively when arranged randomly.

The researchers focused on the thermoelectric alloy Bi0.4Sb1.6Te3 as a model system. Utilizing advanced electron microscopy and scanning thermal probe techniques, they mapped the composition and thermal properties of this bismuth-antimony-telluride compound at the atomic level. Their analysis showed that materials with a more random mixture of bismuth- and antimony-rich zones were better at blocking heat than those with a more ordered structure.

Liu noted that the random scattering of edge dislocations disrupts heat flow, leading to the observed low thermal conductivity.

Implications for Future Material Design

The team leader, Professor Zhi-Gang Chen, emphasized the potential of this discovery to open new pathways for designing materials with tailored thermal properties. “By understanding how these dislocations form and align, we can better engineer materials for energy applications,” Chen stated. He added that this structural insight offers a new design principle for developing low thermal conductivity materials that go beyond traditional defect engineering.

Liu further explained that the findings could have broad implications across various industries. “Whether it’s improving the efficiency of thermoelectric generators or developing better thermal insulators, this work gives us a new tool to control heat flow at the atomic level,” he said.

The full QUT research team, all affiliated with the QUT Center for Material Science, includes Dr. Wei-Di Liu, Dr. Wanyu Lyu, Yicheng Yue, Dr. Han Gao, Dr. Meng Li, Dr. Xiao-Lei Shi, and Professor Zhi-Gang Chen, alongside James D. Riches from QUT’s Central Analytical Research Facility (CARF) and Dmitri Golberg, a distinguished professor at the QUT School of Chemistry and Physics.

This research marks a significant advancement in material science, providing essential insights that could lead to more efficient thermoelectric devices and innovative thermal management solutions.