Combining Research to Improve Understanding of Thermal Conductivity
Whether it is our cars or computers, we are all familiar with systems that waste energy as heat. Depending on the specific system, the amount of energy lost can be significant so researchers are working on thermoelectric materials to capture some of that energy. There has been a mystery about some of these materials, and other materials that researchers at MIT may have finally solved.
One would expect that similar materials would have similar properties, but in reality, this may not be the case. For some time researchers have been vexed about why one material may be a good thermal insulator, while a similar material is not. The answer the MIT researchers have found has not come from thermoelectric research though, but from research into phase-change materials. These materials can significantly change their properties in response to a change in temperature because of resonant bonding. Resonant bonds have electrons that flip between several adjacent atoms and while their impacts on electrical and optical properties have been studied, thermal properties have not been. The researchers have found that it is in fact long-range interactions of these flipping bonds that causes the varying thermal conductivity in similar materials.
Thermoelectric devices work by producing a voltage across a material, when there is a heat differential, so a low thermal conductivity is needed to maintain the differential. By better understanding what affects a material's thermal conductivity, we can better predict and design materials for specific applications.