I’m writing this from a laptop that’s stalling and refusing to switch between tabs because it’s gotten too warm in the early Indian summer. It’s not like I’m running a hectic workload of video and audio editing tools and multiple browsers at once: this old machine just can’t move heat away from the processor and other internals quickly enough.
That results in throttling, or reducing the clock speed at high temperatures, in order to prevent overheating and damage to the internal components. But a new finding from the University of Virginia School of Engineering and Applied Science could make that a thing of the past – with crystals.
When electronic components like the processor in your laptop are working at full tilt, they can get pretty hot. The same can be said for chips in a range of other devices, and even batteries in electric cars. Now, if these components are squashed into tight spaces, you’re going to see heat build up there and take a long time to dissipate.
Staying on the laptop example – you could speed up heat dispersion with a fan, a liquid cooling system, or a heat sink with metal fins. All of these take up precious space inside a device, and draw power.
Researchers have hit upon a much quicker alternative. Rather than having the heat move away slowly like ripples in a pond, their approach transforms heat into channeled waves that travel more quickly.
To pull this off, the team used a kind of crystal called hexagonal boron nitride (hBN), which has certain special properties that can be leveraged to move heat quickly through it.
In most materials, heat is carried by vibrations of atoms called phonons. These phonons collide with each other and transfer their energy in a random, step-by-step process. Unfortunately, the group velocities, or the speed of energy passing through these materials, is usually pretty slow. That’s what causes heat to build up and keep your devices toasty.
Now in hBN, we see a different mechanism known as hyperbolic phonon polariton (HPhP) modes. That refers to a special type of vibration within the crystal, coupled with a light-like component in the form of electromagnetic waves.
The HPhP modes provide a much faster “lane” for heat to travel than traditional heat dissipation, driven by radiative energy transfer and their inherently high propagation speeds.
Think of it like a fast, directed current (HPhPs) versus a slow, random movement of a crowd (phonons). The current can move a large amount of “energy” (people) much more quickly from one point to another.
To demonstrate this, the researchers put a gold pad on an hBN substrate, and heated the gold. This excited the hBN’s HPhP modes, enabling the rapid transfer of heat away from the interface between the gold pad and the hBN. In fact, the heat transfer was said to be 10 to 100 times more efficient at the interface when HPhPs were involved.
“This method is incredibly fast,” explained Will Hutchins, who authored the study that appeared in Nature Materials last month. “We’re seeing heat move in ways that weren’t thought possible in solid materials. It’s a completely new way to control temperature at the nanoscale.”
The discovery could apply to other combinations of materials as well, and could unlock ways to create cooling systems for a wide range of electronic components. That means faster AI-powered computers and data centers, longer-lasting medical devices, and yes, less throttling in future laptops.
Source: University of Virginia School of Engineering and Applied Science