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Diamonds may be the strongest natural material known, but researchers have just created fierce competition.
By pulling a penny-sized disc of graphite across a wall at 24,100 km / h, scientists momentarily created a hexagonal diamond that is both stiffer and stronger than the natural cubic type.
Hexagonal diamonds, also known as Lonsdaleite diamonds, are a special type of diamond with carbon atoms arranged in a hexagonal pattern. Formed when graphite is exposed to extreme heat and stress, such as at meteor impact sites, the rare material has long been theorized to be stronger than ordinary cubic diamonds.
However, because the hexagonal diamonds found in impact craters contain too many impurities, scientists have never accurately measured their properties.
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Now, researchers have not only forged hexagonal diamonds, but also measured their stiffness – the ability to resist changes in shape when crushed or stretched – with a combination of sound waves and laser light.
“Diamond is a very unique material,” study co-author Yogendra Gupta, director of the Institute for Shock Physics at Washington State University, said in a press release. “It is not only the strongest – it has beautiful optical properties and very high thermal conductivity. We have now manufactured the hexagonal shape of the diamond, produced under impact compression experiments, which is significantly more rigid and more solid than ordinary gemstone diamonds. “
Cubic diamonds typically form more than 150 kilometers below the Earth’s surface, under extreme pressures many times greater than the crushing depths of the deep ocean and temperatures above 2,732 degrees Fahrenheit (1,500 degrees Celsius). But to form hexagonal diamonds, the researchers mimicked the high-energy impact of a meteor strike, using gunpowder and compressed air to launch the graphite disks at incredible speeds. As the discs collided with a wall, shock waves from the impact quickly transformed the discs into hexagonal diamonds.
To measure the strength and stiffness of diamonds in a fraction of a second before the minerals were shattered into a thousand pieces, the researchers emitted a sound wave and measured the speed at which it was traveling through the hexagonal diamonds with a laser. (Sound waves cause the density of the diamond to fluctuate as it moves, which affects the length of the laser beam path.) The stiffer a material, the faster sound passes through it.
It is difficult to tell if hexagonal diamonds are harder than the average diamond. Hardness is a measure of how difficult it is to scratch a material’s surface, and hexagonal diamonds weren’t around long enough for scientists to scratch them.
At present, scientists have not found a way to create more long-lived hexagonal diamonds in the lab, but if a method is discovered, researchers predict a range of uses for them – tips of more efficient drill bits to more sophisticated engagement rings. .
“If one day we can produce and polish them, I think they would be in more demand than cubic diamonds,” Gupta said. “If someone said to you, ‘Look, I’ll give you a choice of two diamonds: one is much rarer than the other.’ Which would you choose? “
The researchers published their results on March 31 in the Journal Physical examination B.
Originally posted on Live Science.
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