Researchers create two types of diamonds at room temperature

Date:20 November 2020 Author: Kyro Mitchell

Researchers from the Australian National University and RMIT University have managed to create two types of diamonds at room temperature. One of the diamonds is the regular kind that you’d find in a wedding ring, while the other is called Lonsdaleite, a type of diamond found at meteorite impact sites.

When a diamond is formed in nature, it is usually done deep inside the Earth at a depth of around 150 kilometers. At this depth, pressures are extremely high and temperatures can reach above 1000 degrees Celsius. In creating the diamonds, researchers replicated the pressure felt deep below the Earth’s surface, but not the extreme temperatures.

According to the researchers, “This new unexpected discovery shows both Lonsdaleite and regular diamond can also form at normal room temperatures by just applying high pressures – equivalent to 640 African elephants on the tip of a ballet shoe.”

Researchers discovered that at high pressures, the carbon used to make the diamonds experiences something called “shear,” which is similar to a twisting or sliding force, which they believe allows the carbon atoms to move into place and form Lonsdaleite and regular diamond.

Thanks to the use of advanced electron microscope techniques, researchers were able to capture solid and intact slices from the experimental samples to create snapshots of how the two types of diamonds formed.

“Our pictures showed that the regular diamonds only form in the middle of these Lonsdaleite veins under this new method developed by our cross-institutional team,” said co-lead researcher Professor Dougal McCulloch.

“Seeing these little ‘rivers’ of Lonsdaleite and regular diamond for the first time was just amazing and really helps us understand how they might form,” he added.

Due to its unique crystal structure, lonsdaleite diamonds are believed to be 58 percent harder than regular diamonds. This means, for example, they could be used at mining sites to quickly cut through extremely solid materials.

Picture: Jamie Kidston, ANU


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