BC8 superdiamonds are harder than any known material, but are likely only found in the cores of giant exoplanets. Now, the Frontier supercomputer has unlocked the secret of their formation, a finding that could lead to their production on Earth.
Diamonds don’t just make stunning jewelry, they’re also used in a variety of applications around the world. As the hardest substance on earth and thanks to their unique structure, they play a role in everything from drilling advanced geothermal wells to serving as semiconductors in nuclear batteries.
Well, imagine what possibilities would arise if we could create a material that is even harder than the hardest material known to humanity.
In fact, scientists have been predicting this for years. They predicted that a material containing eight carbon atoms for every four found in diamond could exist under the extreme heat and pressure found in the cores of planets at least twice as massive as Earth.
Known as BC8 (octatom body-centered cubic), this “superdiamond” might be possible to create in the lab, but the conditions required to replicate it are challenging, to say the least. A replicator would need to reach 10 million times the pressure of the Earth's atmosphere and temperatures approaching the surface temperature of the sun, so running multiple physical experiments to attempt to produce BC8 is somewhat impractical.
The world’s fastest supercomputer, Frontier, is based at the Department of Energy’s Oak Ridge Laboratory. It has the power to run millions of atomic modeling states on millions of sets of conditions to determine exactly what it would take to create BC8. A team of researchers led by Ivan Oleynik, lead author of the study and a professor of physics at the University of South Florida, got access to Frontier to see if it could help them crack the BC8 code, and it worked.
Philosopher's Stone
“This is the ultimate challenge of high-pressure physics,” Oleynik said. “This is our version of the philosopher's stone, which medieval alchemists believed would turn lead into gold if they could find it. The alchemists had no Frontier.”
The professor and his team sent Frontier an incredible amount of data to train a software module known as LAMMPS, which stands for Large-scale Atomic/Molecular Massively Parallel Simulator, and performs the necessary calculations. Other computers were too slow to run the program, Oleynik said.
“We basically got a fingerprint of every atomic environment around every atom in a billion-atom system that could arise during the evolution of the system at extreme pressures and temperatures,” Oleynik said. “Without Frontier, this would have been impossible.”
“For this study, we needed to simulate more than a billion atoms while performing up to a million time steps in molecular dynamics simulations,” he added. “We had access to other supercomputers, but none had enough computing power to even handle that many atoms.”
'Shocking discovery
After running LAMMPS for about 24 hours using 8,000 of Frontier’s 9,400-plus nodes, the team got an answer that showed a unique and somewhat surprising step that would be required to convert carbon into BC8. They found that conventional diamonds must melt before the carbon liquid can rearrange into BC8’s super-strong structure.
“This is a new discovery in this sense because in most cases materials transform from one crystal phase to another by coordinated rearrangement of the atomic structure,” Oleynik said. “But the carbon bonds that make up a diamond are so strong that we have to melt the diamond to transform it into a new BC8 crystal phase. This adds another layer of even more extreme pressures and temperatures to the process – 12 million times the pressure of the Earth's atmosphere and 5,000 K, close to the surface temperature of the sun.”
The research revealed that such conditions could be created by a series of shock waves, providing the team with exactly the right level of waves to reach the temperatures and pressures required for BC8 to form.
Now the team is putting that knowledge to the test by trying to synthesize BC8 at Lawrence Livermore National Laboratory’s National Ignition Facility, a stadium-sized nuclear fusion facility that uses 192 powerful lasers to create temperatures above 180 million degrees Fahrenheit and pressures greater than 100 billion Earth atmospheres.
“Thanks to Frontier, we have a good chance of success,” Oleynik concluded. “It is an extreme challenge with no guarantees, but we have great confidence in these results.”
The video below provides more information about the findings.
Can Frontier help build a better diamond?
The results of the study were reported as follows: Journal of Physical Chemistry Letters.
Source: Oak Ridge National Laboratory