Science

Scientists develop material that's harder than diamonds

Scientists develop material th...
Simulated structure of buckyballs and new super-hard material (Image: Lin Wang, Carnegie Institution of Washington)
Simulated structure of buckyballs and new super-hard material (Image: Lin Wang, Carnegie Institution of Washington)
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Schematic of a diamond anvil cell with ruby acting as pressure standard (Image: Tobias1984)
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Schematic of a diamond anvil cell with ruby acting as pressure standard (Image: Tobias1984)
Simulated structure of buckyballs and new super-hard material (Image: Lin Wang, Carnegie Institution of Washington)
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Simulated structure of buckyballs and new super-hard material (Image: Lin Wang, Carnegie Institution of Washington)

Diamonds may be forever, but they aren’t what they were. True, they shine just as brightly and they’re as hard as ever, but scientists from the Carnegie Institution of Washington are giving them some competition. An international team led by Carnegie’s Lin Wang has discovered a new substance that is not quite crystalline and not quite non-crystalline, yet is hard enough to dent diamonds.

The new substance, which has yet to be named, is described by Wendy Mao, a Stanford University professor, as a “hybridization of crystalline and amorphous structures at an atomic level.” It was also something of a surprise to the Carnegie team.

The super-hard material started out as clusters of carbon-60 – the soccer-ball shaped molecules of carbon commonly known as "“buckyballs." These were mixed with m-xylene solvent, which is used in the manufacture of soft drink bottles. The mixture was then placed in a diamond cell anvil at the Argonne National Laboratory's Advanced Photon Source in Argonne, Illinois.

Schematic of a diamond anvil cell with ruby acting as pressure standard (Image: Tobias1984)
Schematic of a diamond anvil cell with ruby acting as pressure standard (Image: Tobias1984)

The diamond cell anvil was key to the experiment. This is a super high-pressure chamber made of two flat-faced diamonds. The buckyball/solvent mixture is placed in a cell between the diamonds and pressure is applied. As the diamonds squeeze together, the mixture is subjected to a pressure of, in this case, 600,000 atmospheres. Not surprisingly, the buckyballs were crushed. What was mildly surprising was that properties of the former buckyballs were altered until they became hard enough to dent the diamonds. That is not unprecedented, but what was very surprising was that the new substance retained its structure once the incredible pressure was removed. What was even more surprising was that it turned out to be a substance that no one had seen before.

All solid matter comes in one of two forms. Either it has an ordered, crystalline structure, like quartz or iron or diamonds, or it is non-crystalline or amorphous, like glass or gels. What this new substance has is both. If you apply massive pressure to buckyballs, you should get mashed buckyballs, but the m-xylene reacted with the carbon in some manner so that it retained a long-range, regular molecular structure. In other words, it retained the order of a crystal despite its crystalline structure being destroyed.

According to Wang, there is more here than a laboratory curiosity. “We created a new type of carbon material, one that is comparable to diamond in its inability to be compressed,” Wang said. “Once created under extreme pressures, this material can exist at normal conditions, meaning it could be used for a wide array of practical applications.”

Exactly what these applications are remain unknown, though it could be as a protective coating or find mechanical, electronic, and electrochemical uses.

Sources: Carnegie Institution for Science

Stanford University

15 comments
5318008
Or possibly Captain America's shield.
yrag
"yet is hard enough to dent diamonds." Diamonds are crystalline, they can be chipped or shattered, 'pretty sure' they cannot be bent.
Pikeman
How much does it cost? How slick is it? Is better used as an abrasive or wear surface? How well does it conduct heat and electricity? Is it pretty?
Geometeer
Crystals cannot be dented? Not if you insist that they remain perfect crystals -- that includes a fixed geometry -- but real crystals don't. You'll find nice clear diagrams of how a crystal deforms at http://www.sut.ac.th/engineering/metal/pdf/MechMet/04_Plastic%20deformation%20of%20single%20crystal.pdf. With diamonds it takes big forces: but 600,000 atmospheres is a lot of force. As for how much it costs, far too early to ask. The only samples are the ones created in a diamond anvil, probably very small. They may be so small that we don't yet know how a visible piece of the stuff would look in ordinary light. (Remember, gold in small small bits is purple!)
Rt1583
@yrag - Metal is crystalline and it can be bent and dented.
Fretting Freddy the Ferret pressing the Fret
@Geometeer You mean colloidal gold in dispersion is purple.
Anton McInerney
What a great foundation material for the Makers!
dwainez
Give it to DARPA. For a few hundred billion more dollars, we'll have a new super tank and better body armor for the troops.
Dawar Saify
This substance will also have tensile strength. It could be used in strong transparent items, like bullet proof glass, and riot shields and could replace metal in some cases and in the future used in structures.
Simon Burdett
Armour piercing rounds come to mind. All the penetration without the fall out. No more "crispy critters" :-P