Scientists create ultra-hard diamonds at room temperature

Diamonds may not be as rare or everlasting as diamond miners would like everyone to believe, but they are still rare enough that creating synthetic diamonds is a worthwhile scientific endeavor. Natural diamonds only form deep in the Earth under intense heat and pressure, but researchers at Australian National University (ANU) and RMIT University say they have developed a way to create diamonds at room temperature, and some of them are harder than your -of-the-mill gemstone race.

While the team didn’t need extreme heat to make diamonds, they did need a lot of pressure. Using a device known as a diamond anvil cell, the team squeezed carbon atoms with force equivalent to 640 African elephants. That’s the awesome large number, but it was also a matter of finesse – the way researchers applied that pressure was the key to creating not one but two types of diamonds.

The anvil cell was configured in such a way that the samples could undergo a shear force. The researchers hypothesize that this twisting and sliding motion allows carbon atoms to reorient themselves to form a solid diamond lattice. However, you can’t just throw some charcoal in and come out with a sparkling gemstone. The resulting samples are a mishmash of ordinary diamond and an alternate form of diamond called Lonsdaleite. They almost missed it too. The sample did not have the properties expected after being exposed to so much pressure, but microscopic examination of the carbon atoms showed large blocks of Lonsdaleite surrounding bands of pure diamond.

The diamond found in these tiny veins is the same material that makes up diamond gemstones but in very small amounts. This research is mainly focused on the creation of diamonds for industrial and scientific purposes, which means Lonsdaleite is the most interesting find. Lonsdaleite is a hexagonal diamond and is theoretically much stronger than the “regular” diamond, which has a cubic lattice.

Tests suggest that Lonsdaleite could be 58% harder than these cubic diamonds, and there is nowhere on Earth where we can mine Lonsdaleite in significant amounts. Lonsdaleite exists in microscopic amounts in geological formations around some meteorite impact sites. So the possibility that we can produce Lonsdaleite in the lab is exciting. If you need to cut something very hard, diamond is a common material to use in your tools. An even harder diamond is naturally even better, and that could be the end result of this research. The team hopes to find a way to produce significant amounts of Lonsdaleite in the future.

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