This image shows how rotational disorder affects thermal conductivity in superatom crystals. Image: Ryan Hastie, Department of Chemistry, Columbia University.Researchers have found that the thermal conductivity of superatom crystals is directly related to the rotational disorder within those structures. They publish their findings in a paper in Nature Materials.
Superatom crystals are periodic – or regular – arrangements of soccer ball-shaped C60 fullerenes, also known as buckyballs, and similarly-sized inorganic molecular clusters, and they come in two different forms.
"There are two nearly identical formations, one that has rotating (i.e. orientationally disordered) C60s and one that has fixed C60s," said Jonathan Malen, associate professor of mechanical engineering at Carnegie Mellon University and a corresponding author of the paper. "We discovered that the formation that contained rotating C60s has low thermal conductivity while the formation with fixed C60s has high thermal conductivity."
Although rotational disorder is known in bulk C60, this is the first time the process has been leveraged to create very different thermal conductivities in structurally-identical materials.
Imagine a line of people passing sandbags from one end to the other, says Malen. Now imagine a second line where each person is spinning around – some clockwise, some counter clockwise, some fast and some slow. It would be very difficult to move a sandbag down that line.
"This is similar to what is happening with thermal conductivity in the superatoms," he explained. "It is easier to transfer heat energy along a fixed pattern than a disordered one."
Xavier Roy, assistant professor of chemistry at Columbia University and the other corresponding author of the paper, created the superatom crystals in his laboratory by synthesizing and assembling the building blocks into the hierarchical superstructures.
"Superatom crystals represent a new class of materials with potential for applications in sustainable energy generation, energy storage and nanoelectronics," said Roy. "Because we have a vast library of superatoms that can self-assemble, these materials offer a modular approach to create complex yet tunable atomically-precise structures."
The researchers believe these findings will lead to further investigations into the unique electronic and magnetic properties of super-structured materials. One future application might include a new material that could change from being a thermal conductor to a thermal insulator, opening up the possibility of new kinds of thermal switches and transistors.
"If we could actively control rotational disorder, we would create a new paradigm for thermal transport," said Malen.
This story is adapted from material from Carnegie Mellon University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.