|Researchers at MIT and elsewhere have succeeded in creating a synthetic crystal that can very effectively control the transmission of heat -- stopping it in its tracks and reflecting it back. This advance could lead to insulating materials that could block the escape of heat more effectively than any present insulator.|
This crystal structure was built using alternating layers of silicon dioxide (the basis of the dielectric layers in most microchips) and a polymer material. The resulting two-component material successfully reflected phonons â€" vibrational waves that are the carriers of ordinary heat or sound, depending on their frequency. In this case, the phonons were in the gigahertz range â€" in other words, low-level heat.
|The phonons that are reflected from this newly developed material are in the range of low-frequency heat (since anything above absolute zero, or minus 273 degrees Celsius, is considered heat, which is just due to the movement of vibrational waves). Hence, this reflector currently only works at sub-freezing temperatures. Further work on decreasing the thickness of the layers could bring them closer to the range of a theoretical â€œperfect insulatorâ€ that could block heat of a certain frequency range in an ordinary room-temperature environment. And this could open up a host of potential applications.|