"White Graphene" Structures Can Take the Heat in Electronics
July 17, 2015 | Rice UniversityEstimated reading time: 2 minutes
![](https://iconnect007.com/application/files/5116/3116/8219/white_graphene.jpg)
Three-dimensional structures of boron nitride might be the right stuff to keep small electronics cool, according to scientists at Rice University.
Rice researchers Rouzbeh Shahsavari and Navid Sakhavand have completed the first theoretical analysis of how 3-D boron nitride might be used as a tunable material to control heat flow in such devices.
In its two-dimensional form, hexagonal boron nitride (h-BN), aka white graphene, looks just like the atom-thick form of carbon known as graphene. One well-studied difference is that h-BN is a natural insulator, where perfect graphene presents no barrier to electricity.
Rice researchers Rouzbeh Shahsavari (left) and Navid Sakhavand calculated the flow of heat across simulated structures of hexagonal boron nitride and boron nitride nanotubes. Photo by Jeff Fitlow
But like graphene, h-BN is a good conductor of heat, which can be quantified in the form of phonons. (Technically, a phonon is one part — a “quasiparticle” – in a collective excitation of atoms.) Using boron nitride to control heat flow seemed worthy of a closer look, Shahsavari said.
“Typically in all electronics, it is highly desired to get heat out of the system as quickly and efficiently as possible,” he said. “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.”
Heat moves ballistically across flat planes of boron nitride, too, but the Rice simulations showed that 3-D structures of h-BN planes connected by boron nitride nanotubes would be able to move phonons in all directions, whether in-plane or across planes, Shahsavari said.
The researchers calculated how phonons would flow across four such structures with nanotubes of various lengths and densities. They found the junctions of pillars and planes acted like yellow traffic lights, not stopping but significantly slowing the flow of phonons from layer to layer, Shahsavari said. Both the length and density of the pillars had an effect on the heat flow: more and/or shorter pillars slowed conduction, while longer pillars presented fewer barriers and thus sped things along.
While researchers have already made graphene/carbon nanotube junctions, Shahsavari believed such junctions for boron nitride materials could be just as promising. “Given the insulating properties of boron nitride, they can enable and complement the creation of 3-D, graphene-based nanoelectronics.
“This type of 3-D thermal-management system can open up opportunities for thermal switches, or thermal rectifiers, where the heat flowing in one direction can be different than the reverse direction,” Shahsavari said. “This can be done by changing the shape of the material, or changing its mass – say one side is heavier than the other – to create a switch. The heat would always prefer to go one way, but in the reverse direction it would be slower.”
Shahsavari is an assistant professor of civil and environmental engineering and of materials science and nanoengineering. Sakhavand is a former graduate student at Rice.
The National Science Foundation and the Rice Department of Civil and Environmental Engineering supported the research. The researchers used the National Science Foundation-supported DAVinCI supercomputer administered by Rice’s Ken Kennedy Institute for Information Technology. They also used computing resources supported by the National Institutes of Health, IBM, CISCO, Qlogic and Adaptive Computing.
Suggested Items
Rehm Thermal Systems is Exhibiting for the First Time at hy-fcell
08/06/2024 | Rehm Thermal Systemshy-fcell will once again take place in Stuttgart on 8 and 9 October 2024. The leading international trade fair and conference for hydrogen and fuel cell technology is the meeting place for the industry and offers both experts and newcomers the ideal platform to discuss technological advances, transfer knowledge and open up international markets – for the first time, Rehm Thermal Systems will be exhibiting a system for drying fuel cells.
CTEK Shares Tips to Avoid a Dead Battery in Summer Heat
07/26/2024 | PRNewswireThe United States has seen record heat and it doesn't look like it will end anytime soon. As the heat intensifies, it's not just our bodies that need extra care and attention; CTEK says our vehicle batteries also require special consideration to ensure optimal performance and reliability.
Thermal Greases for Computers, Electronics and High Tech Devices
07/19/2024 | epoxySetepoxySet produces a wide range of over 40 different thermally conductive greases. These greases are both silicone-based and silicone-free hydrocarbons.
Rocket Lab Sets Date for Second NASA PREFIRE Launch
05/30/2024 | BUSINESS WIRERocket Lab USA, Inc., a global leader in launch services and space systems, confirmed the scheduled launch date for the second of two back-to-back Electron launches for NASA’s PREFIRE (Polar Radiant Energy in the Far-InfraRed Experiment) climate change-focused mission.
The Thrill of Victory: IPC Design Competition
05/23/2024 | Michelle Te, I-Connect007The final heat of the 2024 IPC Design Competition took place on Tuesday, April 9, during IPC APEX EXPO. IPC’s Kris Moyer and Patrick Crawford served as judges and onsite supervisors for the event, which featured five competitors—four online and one live at IPC APEX EXPO. The grand prize winner was Dinesh G., followed by Paul Brionez in second place (he placed third last year), Ajeesh Francis in third, and runners-up Joseph Chiu and Harish G (last year’s champion).