The Hardest Substance on Earth Just Got Harder

Written by: James Wilkey
Written by: James Wilkey

As you gaze into the luster of a diamond, it’s easy to forget that, once upon a time, that shining stone wasn’t so different from a lump of coal (give or take a few million years, at least 700,000 pounds of pressure per square inch, and about 2,000 degrees Fahrenheit!). Although most people conjure up images of engagement rings and fashion accessories when they hear the word “diamond,” the tiny, yet shockingly-hard stone actually plays a much more vital role in our modern society. As the hardest substance known to man, diamonds are used in many industrial products, such as drill bits and laser beams, which help create infrastructure, automobiles, and medical supplies.

Despite their usefulness, diamonds can be difficult and expensive to make. For instance, artificial diamonds often require catalyzing gasses to facilitate formation. They also require equipment capable of mirroring the same kind of pressure and temperature required in natural diamond formation. These costly and complicated requirements don’t always make diamonds a viable option for manufacturers.

Fortunately, the researchers at North Carolina State University are working to change all that by making diamonds easier and faster to produce. If that wasn’t enough, they’re also working to make diamonds even harder than they currently are! And they’re doing it all with the use of a new and simple process involving lasers.

A micrograph of a q-carbon film showing microdiamonds made using the new technique. (Journal of Applied Physics)
A micrograph of a Q-Carbon film showing microdiamonds made using the new technique. (Journal of Applied Physics)

In this new process, a film of carbon is heated to 6,740 degrees Fahrenheit. Afterward, it is jolted by a burst of energy from a laser beam for precisely 200 nanoseconds. The laser melts the carbon, which then cools to form a new crystal lattice structure. Depending on both the cooling rate of the carbon and the intensity of the laser, the result could be a synthetic diamond or a completely new type of diamond. The entire process takes just 15 minutes! And it is created at room temperature without pressure.

If having a diamond in 15 minutes wasn’t enough, the laser process also produces a new type of diamond called Q-Carbon. Q-Carbon is made-up of an entirely new “phase” of carbon. In other words, the new laser process rearranges the carbon molecules into a never-before-seen pattern. In fact, up until now, graphite and diamond were the only know phases of the element. Although Q-Carbon could hypothetically exist in nature, such as in planet cores, the likelihood of encountering Q-Carbon naturally is extremely unlikely because of the intense pressure that such a natural formation would require.

There are many benefits to the new Q-Carbon. However, its greatest appeal is its unmatched hardness. Q-Carbon is 60% harder than diamonds, making it the hardest substance known to man. This characteristic is due to its unique phase. Additionally, Q-Carbon also has properties that make it potentially applicable in ferromagnetism, fluorescence, and electrical conductivity. Thus, the stone is likely to be as useful to scientists as it is to industrialists. Lastly, Q-Carbon’s cost-effectiveness, simplicity, and efficiency could prove a huge boon to manufacturers of drill bits, lasers, heat sinks, and other equipment for which synthetic diamonds are an essential component.

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