This is a scanning electron microscopy image of microdiamonds made using the new technique.
Q-carbon is distinct from known phases of graphite and diamond. They have also developed a technique for using Q-carbon to make diamond-related structures at room temperature and at ambient atmospheric pressure in air. “We’ve now created a third solid phase of carbon,” says Prof. Jay Narayan. “The only place it may be found in the natural world would be possibly in the core of some planets.”
Q-carbon has some unusual characteristics
~It is ferromagnetic -other solid forms of carbon are not.
“We didn’t even think that was possible,” Narayan says.
~It is harder than diamond, and glows when exposed to even low levels of energy.
~”Q-carbon’s strength and low work-function – its willingness to release electrons – make it very promising for developing new electronic display technologies,” Narayan says.
But Q-carbon can also be used to create a variety of single-crystal diamond objects. To understand that, you have to understand the process for creating Q-carbon. Researchers start with a substrate, eg sapphire, glass or a plastic polymer. The substrate is then coated with amorphous carbon – elemental carbon that, unlike graphite or diamond, does not have a regular, well-defined crystalline structure. The carbon is then hit with a single laser pulse lasting ~200 nanoseconds. During this pulse, the temperature of the carbon is raised to 4,000 Kelvin (3,727 C ) and then rapidly cooled. This operation takes place at one atmosphere – the same pressure as the surrounding air.
The end result is a film of Q-carbon, and the process can be controlled to make films 20-500 nm thick. By using different substrates and changing the duration of the laser pulse, they can also control how quickly the carbon cools. By changing the rate of cooling, they are able to create diamond structures within the Q-carbon.
“We can create diamond nanoneedles or microneedles, nanodots, or large-area diamond film, with applications for drug delivery, industrial processes and for creating high-temperature switches and power electronics,” Narayan says. “These diamond objects have a single-crystalline structure, making them stronger than polycrystalline materials. And it is all done at room temperature and at ambient atmosphere – we’re basically using a laser like the ones used for laser eye surgery. So, not only does this allow us to develop new applications, but the process itself is relatively inexpensive.” And, if researchers want to convert more of the Q-carbon to diamond, they can simply repeat the laser-pulse/cooling process.
If Q-carbon is harder than diamond, why would someone want to make diamond nanodots instead of Q-carbon ones? Because we still have a lot to learn about this new material.
“We can make Q-carbon films, and we’re learning its properties, but we are still in the early stages of understanding how to manipulate it,” Narayan says. NC State has filed two provisional patents on the Q-carbon and diamond creation techniques.
https://news.ncsu.edu/2015/11/narayan-q-carbon-2015/
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