This discovery is based on the useful but confusing idea of quasiparticles that behave as if they exist but don’t really exist. Solids have only three types of particles: protons, neutrons, and electrons. These individual particles are very difficult to predict when packed into a solid. This is because in a highly chaotic many-body problem each motion is directly influenced by all other motions.
But despite this insane complexity, these systems have an observable emergent mechanism that behaves in a much simpler way, as if they were particles that had no interaction with everything around them. I have a pattern. Researchers have found many of these in various systems and call them quasiparticles. They are, in effect, mathematical tools that allow scientists to work with simple patterns of behavior arising from chaotic systems.
The quasiparticles of interest in this case are ferrons, which are theorized to exist in ferroelectric materials, a subset of piezoelectric materials. Piezoelectrics are materials that generate an AC voltage when subjected to vibration or stress, or vibrate when subjected to an external AC voltage. For example, some microphones use piezoelectric components to convert sound waves into electrical signals. Ferroelectrics are piezoelectrics and also exhibit an electric polarization that can be reversed by the application of an electric field.
Like other quasiparticles, ferrons do not exist. However, they describe waves traveling in a ferroelectric material that carry both heat and polarization, propagating in a predictable manner even though the reality of each particle in the matrix is much more complex. increase.
Researchers at Ohio State University sought to predict and confirm the behavior of ferron using a common lead zirconate titanate ceramic as a ferroelectric material. Their theory is that when an electric field is used to induce piezoelectric oscillations in a ferroelectric material, those oscillations modify the material’s thermal conductivity.
Ohio State University
“We find that changes in the position of these atoms, and changes in the nature of their vibrations, must carry heat. Therefore, external fields that change this vibration must affect thermal conductivity,” and Aerospace Engineering, Materials Science and Engineering, Physics – and senior author of new research published in journals scientific progress – In press releases.
“Feron is also sensitive to solid distortion,” he continued. “Ferron carries heat, so the amount of heat depends on the electric field. So we studied the external electric field, the strain it causes in the ferroelectric, and ultimately how this strain affects the thermal conductivity. I wrote a new theory to relate.”
Tests confirmed their predictions – a fairly mild effect. Applying an electric field to the ceramic produced a difference of 2% between maximum and minimum thermal conductivity. “Any application depends on finding materials that are much more effective,” Hellemanns said. “We’re looking for materials with the right parameters.” The theory predicts that other materials exist whose thermal conductivity he can vary by as much as 15%.
The potential result here is a new type of thermal switch that works without moving parts over various temperature ranges. Most current technologies rely on mechanical valves that fail over time or rely on very low or very specific temperatures to exert their useful effects.
This could dramatically improve the efficiency of thermoelectric systems that convert heat into electricity. “The thermodynamic efficiency of a power generation circuit is highly dependent on the temperature difference between the hot and cold storage tanks,” Heremans tells his IEEE Spectrum. “The use of thermal switches and heat storage systems allows the temperature of the heat storage medium to be much higher than the average temperature of the heat source and close to the maximum, thus doubling the thermal efficiency of the system.”
The article is open access in the journal scientific progress.
Source: Ohio by IEEE Spectrum
