A team of scientists has recently discovered the basic microscopic mechanisms that can contribute to modifying materials used in heat insulation. They are researchers from the Novel Materials and Devices (NOMAD) Laboratory at the Fritz Haber Institute in Berlin, Germany.
Looking Back at the Basic Principles
The NOMAD Lab researchers investigated the role of advanced computational possibilities in measuring thermal conductivities without the need for experimental input at unusual accuracy. They tried to prove this condition is inappropriate for phonon for strong heat insulators.
The researchers used Large-scale calculations with the help of supercomputers at the Max Planck Society, the North-German Supercomputing Alliance, and the Jülich Supercomputing Centre. More than 465 crystalline materials were scanned for thermal conductivity, which had not been measured yet.
Researchers found 28 strong thermal insulators, six showing an ultra-low heat conductivity that can be compared to wood. The result of this study provides an understanding of an overseen mechanism that allows the lowering of thermal conductivity in a systematical way.
"We observed the temporary formation of defect structures that massively influences the atomic motion for an extremely short period of time," said first author Dr. Florian Knoop.
The effects scientists observe are usually neglected in thermal conductivity models because of the short-lived defects. They are also assumed to be irrelevant because they are microscopically localized, unlike the typical heat-transport scales.
The researchers' development can help advance the efforts to improve energy efficiency and sustainability. The calculations performed by Knoop and his team proved that lowering thermal conductivity is possible.
This study can provide new opportunities in fine-tuning and designing thermal insulators with the help of nanotechnology. It can also potentially contribute to advancing energy-efficiency strategies through defect engineering.
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Role of Insulators in Heat Transport
Heat transport is important in scientific and industrial processes, such as turbine technology and catalysis. It also applies to thermoelectric heat converters, which transform waste heat into electricity.
Insulation allows limited transfer of heat energy between the inside and outside of a system. For systems to continue operating in a safe and efficient way, it is important to select a heat insulation material that can provide thermal performance under demanding environmental conditions.
Materials with high heat insulation abilities are crucial in energy conservation and developing sustainable technologies. Such materials allow the retention and utilization of heat that would otherwise get wasted. It is, therefore, important to enhance the design of highly insulating materials because they are key in energy efficiency research.
Although the fundamental physical laws have been understood for almost a century, designing strong thermal insulators remains challenging. Heat transport in semiconducting and insulating materials is explained at the microscopic level in terms of the oscillation of their atoms called phonons.
The oscillation of atoms around their equilibrium site in the crystal framework involves many atoms in solid materials. This means that the phonons cover time scales almost macroscopic in length.
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