What do you need for the crystal to have a very low thermal conductivity?

Lattice thermal conductivity, a fundamental material feature, plays a role in various technological applications, including thermal energy conversion and management. A first-principles model of the minimum lattice thermal conductivity (minL) is proposed based on a unified theoretical study of thermal transport in crystals and glasses. The model indicates a universal behavior in crystals at high temperatures when applied to thousands of inorganic substances.

Crystals that can conduct electrons but not heat have a wide range of potential. Researchers have created a technique for finding and creating these materials.

While crystals are effective heat and electron conductors, some have low thermal conductivity. The new study aims to understand these materials’ characteristics and potential for development. 

Co-author Vidvuds Ozolins, the Tom Steyer and Kat Taylor Professor of Clean Energy Solutions, said, “You want the material to be thermally very insulating, while at the same time, you want to have the crystal so that the electrons can zip through and generate currents.” 

The aim is to develop a thermally insulating material that allows electrons to fly through and produce currents. This method works well for jet engine thermal barrier coatings and energy production.

He said, “This study is about understanding what you need for the crystal to have a very low thermal conductivity that approaches the limits of glass.” 

Researchers observed that these qualities are determined by how the atoms interact with one another as phonons. 

The researchers from Yale University created a theoretical model integrating glass-related ideas to explain how low thermal conductivity occurs in crystals. The study used this model in combination with neural network-aided data analysis. 

The model indicates which materials can be used and controlled to produce a crystal with low thermal connectivity. The next step is to make more detailed calculations to understand the properties better and collaborate with experimentalists to conduct additional research on some of the predicted materials.

Journal Reference:

1. Yi Xia, Chris Wolverton, et al.A unified understanding of minimum lattice thermal conductivity. Proceedings of the National Academy of Sciences. DOI:10.1073/pnas.2302541120