We have already prattled about how graphene can have various potential applications in upcoming technologies, ranging from bullet proof vests to fuel cells. But now it seems another incredible material is rising up to the task of handling physical demands in the realm of practicality. We are talking about the hexagonal boron nitride (h-BN) in its two-dimensional form (also called the ‘white graphene’) that is structurally similar to the atom-thick form of graphene. However, beyond this ‘two-dimensional’ sameness, the white graphene might just have the edge when comes to dissipation of heat in smaller electronics. This is due to h-BN’s effectiveness in conducting heat – a virtue which can be quantified in form of phonons (collective excitation in a periodic, elastic arrangement of atoms or molecules in condensed matter).
To that end, Rice University researchers Rouzbeh Shahsavari and Navid Sakhavand, have had a look at this potential advantage. As a result, they surmised that boron nitride can control the magnitude of heat flow in electronics. Now in conventional terms, most electronics are composed of layered materials. And so, while heat can easily traverse in one direction along a conductive plane, it falters when it comes to layer-by-layer propagation – thus leading to the heating up of the electronic device.
In this case, the scientists found out that flat planes of boron nitride do conduct heat in a similar manner to other materials. But the real advantage of the scope relates to how the 3D structures of these h-BN planes connected by boron nitride nanotubes could possibly displace phonons in all directions (including from one layer to other). This propagation of heat is only slowed down a bit when jumping from the plane (horizontal level) to the pillar (vertical level) of the material structure, as opposed to completely stopping. In fact, longer pillars rather sped up the process of heat propagation due to presence of fewer barriers.
So, what can be the potential applications of a conductive ‘white graphene’? Well, according to Shahsavari, one of the technological outcomes pertains to the creation of 3-D, graphene-based nanoelectronics. He also added –
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.
The study was published in the Applied Materials and Interfaces journal.