Siqi Liu and the team found that unevenly composed materials exhibit lower thermal conductivity because tiny flaws known as edge dislocations scatter heat more effectively when randomly distributed. This challenges models that simply attribute low conductivity to how different components are blended.
The study focused on a widely used thermoelectric alloy (Bi0.4Sb1.6Te3), examining its atomic structure and thermal properties using electron microscopy and scanning thermal probe techniques. The investigation revealed that materials with irregularly mixed bismuth and antimony areas impede heat transfer better than structures with ordered zones. This is attributed to edge dislocations, which disrupt heat flow when their patterns lack order.
Zhi-Gang Chen stated the insight will help engineers tailor materials for improved energy applications. "By understanding how these dislocations form and align, we can better engineer materials for energy applications," Chen said. "This structural insight provides a new design principle for low thermal conductivity materials beyond traditional defect engineering."
Siqi Liu added, "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."
The full QUT team included Siqi Liu, Wei-Di Liu, Wanyu Lyu, Yicheng Yue, Han Gao, Meng Li, Xiao-Lei Shi, and Professor Zhi-Gang Chen. James D. Riches is based at QUT's Central Analytical Research Facility, and Distinguished Professor Dmitri Golberg is affiliated with the QUT School of Chemistry and Physics.
Research Report:Alignment of edge dislocations - the reason lying behind composition inhomogeneity induced low thermal conductivity
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