The author, Martin Maldovan, a researcher at the institute, engineered materials that consist of nanostructured semiconductor alloy crystals. Considering that heat is basically a vibration of matter, it can be treated as a stream of photons, similar to the photons that carry light.
The study was published in the latest issue of the journal Physical Review Letters. The article describes how tiny spacing within the materials can be tuned to match wavelength of the heat photons.
The approach is completely new, as Maldovan states. The main difference between heat and sound is in the frequency of vibrations, which is very high for the former, and very low for the latter. To make the technique work, Maldovan had to first bring down the frequency of heat photons and make it similar to this of sound.
He explains that this was possible by making alloys of silicon, which contain nanoparticles of geranium. In addition he made a series of thin films of the material, which assist the scattering of the photons. As a result, more than 40% of the heat photons are concentrated within a relatively narrow range of frequencies- between 100 and 300 gigaherts.
Maldovan is proud to present the new heat-controlling crystals- “thermocrystals”, which have various applications including improved thermoelectric devices, which can transmit electricity freely while controlling the heat. Among the many other applications, he suggests that these can be used to create thermal diodes that control the direction of the heat.