Graphene looks like the promise of future materials, with research looking into using the wonder material in processors, solar cells, headphones, batteries and lately, cooling technology.
A research team from Rice University, comprised of Rouzbeh Shahsavari and Navid Sakhavand has recently concluded the study of 3D hexagonal boron nitride (h-BN), also known as white graphene and its application in cooling technology, particularly with reference to small devices.
According to the researchers, white graphene is the best material choice to tune and control the heat flow in small devices.
An analysis of h-BN in the two-dimensional form will place it very close to graphene atomwise. With the notable difference that two-dimensional h-BN insulates naturally, while graphene allow electricity to flow without any barrier.
So, while the surface of graphene allows easy heat flow, the same doesn’t hold true for the stacked layers of graphene. Rice University researchers looked at solutions to improve heat flow and discovered that if 3D white graphene structures are coupled with h-BN nanotubes, then heat will transfer in all directions across layers and surfaces without any barrier.
Rouzbeh Shahsavari explained:
“Typically in all electronics, it is highly desired to get heat out of the system as quickly and efficiently as possible. One of the drawbacks in electronics, especially when you have layered materials on a substrate, is that heat moves very quickly in one direction, along a conductive plane, but not so good from layer to layer. Multiple stacked graphene layers is a good example of this”.
Shahsavari and Sakhavand calculated the possible flows of phonons across four structures of 3D white graphene with nanotubes fit to different densities and lengths. The meeting points of the in-planes represented by the 3D white graphene structures and the cross-planes represented by the nanotubes significantly slowed the heat flow from one layer to another.
The longer the h-BN nanotubes, the faster the heat flow. The shorter the nanotubes, the slower the heat flow on the white graphene layers.
The study holds great potential for more efficient cooling solutions for small, yet powerful electronic devices.
The study was supported by the National Science Foundation, as well as the Rice Department of Civil and Environmental Engineering.
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