Measuring how heat moves through materials is crucial for developing efficient electronics and energy devices. For example, better heat management can lead to faster and more reliable computers, as well as more efficient solar panels and batteries.

“Finding the right materials for electronics is crucial in developing the devices we need to support the green transition. For instance, when turning heat into electricity – or vice versa - we need materials that lose very little heat but at the same time are great electrical conductors,” says Nini Pryds, a professor at DTU Energy.

“To that end, we want to find out how heat is dispersed in the materials we use. By observing this, we can determine how heat moves in different directions within the material, which is important because it affects their performance.”

The trick is to find materials that perform reliably at the nanometer scale. At this scale small changes in the way heat is conducted can be central to the material's overall performance. For instance, heat can be transported in different directions depending on a certain arrangement of crystals, the grain size or shape, which affects the material’s ability to transform heat into electricity - its thermoelectric properties - and may lead to a less effective device.

There are ways to study heat transport, but the methods are often slow, require complex setups, or risk damaging the materials being studied. This has made it difficult for researchers to get accurate and reliable data to evaluate their performance.

It takes a microscope

In a recent paper in Science Advances, a team of scientists from DTU, Technion, and the University of Antwerp have introduced a new microscopy method that addresses these issues: a thermal diffusivity microscope. The new method is based on a fully automated measurement platform, the CAPRES microRSP. Unlike existing methods, it doesn’t require any special preparation of the sample.

The new microscope can perform high-resolution measurements on a very small scale. The scientists performed their test on two materials known for their excellent heat and electricity conduction properties: Bi2Te3 (bismuth telluride) and Sb2Te3 (antimony telluride), which are often used in thermoelectric devices that convert heat into electricity.

The microscope accurately measured the directional heat flow in these materials. In other words, it can detect how heat moves differently in various directions, providing valuable insights for designing more efficient devices. The findings were confirmed by comparing the new method with other established techniques, showing that the microscope is both reliable and effective.

“I believe our new microscopy method is a significant step forward in the field of materials science. We have developed a fast, simple, and non-damaging way to measure heat flow that gives us a better understanding of how these materials behave,” says Nini Pryds.