Q-carbon is harder than diamond, incredibly simple to make – ExtremeTech
A new phase of carbon has been discovered, dubbed Q-carbon by its creators at North Carolina State University, and it has a number of incredible new properties. Not only does it appear to be harder than its close carbonaceous cousin, diamond, but it actually has properties the scientists themselves did not think possible. Q-carbon is ferromagnetic, something no other phase of carbon is known to be, and it even glows when exposed to energy. But, exciting as these things are, the most proximate application for Q-carbon is in back-conversion to more natural carbon crystals: With a simple melting process, Q-carbon can be turned to diamond under forgiving conditions.
One interesting thing about Q-carbon is that it’s so new, its own discoverers don’t make too many claims about exactly what it is on a chemical level. They make it by putting down layers of “amorphous carbon,” or unordered carbon molecules, onto a substrate like sapphire or glass. By laser-blasting these layers to above 4000K at atmospheric pressure, they can cause the whole thing to enter a molten state — and exactly how they allow this state to end and cool determines what they get at the end. Their studies went toward creating Q-carbon, which they say has mostly four-way carbon bonds, like those in diamond, but also a fair number of three-way bonds.
In principle, this ought to make the crystal lattice less sturdy. But the researchers say that their non-homogenous crystal lattice could be “expected to possess novel physical, chemical, mechanical, and catalytic properties.”
They found such unexpected properties quickly enough. Though it would not even thought to be possible, it seems that in its Q-form, carbon can be ferromagnetic. It’s not like a super-magnet or anything, but the bare fact that this substance can react that way to an applied magnetic field is fascinating to materials scientists. And, of course, there’s the fact that Q-carbons seems to glow when exposed to even a small amount of energy.
Their technique can lay down layers of Q-carbon between 20 and 500 nanometers thick. These layers exhibit hardness well in excess of diamond layers, by as much as 60% if the researchers are correct. They suggest that this could be due to the shorter average carbon-carbon bond lengths in Q-carbon.
Depending on just how the Q-carbon is made, it can end up with embedded nano-diamonds, or diamond nano-needles, which are basically just areas of the Q-carbon which did fuse into the perfect diamond lattice structure. But they can also intentionally back-convert the Q-carbon to diamond nanodots, though the exact properties of that diamond aren’t detailed. It’s likely they’re going to be able to be made into gemstone quality, but the industrial diamond market is still enormous.
This isn’t the first time that the materials industry has claimed to have beaten diamond in one way or another. What sets this apart is the ease of the production process, and the fact that while Q-carbon is new and largely unknown, it can be converted to diamond, which is extremely well understood. We don’t know what uses scientists might find for this new phase of carbon, but since it can be created without the need for extreme conditions, there is at least a wide variety of researchers who are in a position to be able to find out.