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November 23, 2020
Imagine 640 African elephants balancing on the tip of a ballet shoe. That was the amount of pressure scientists needed to transform carbon into diamonds — at room temperature. The scientists defied nature by taking heat out of the equation of how diamonds are formed.
“Natural diamonds are usually formed over billions of years, about 150 kilometers deep (93 miles) in the Earth where there are high pressures and temperatures above 1,000 degrees Celsius (1832 degrees Fahrenheit),” said Professor Bradby from The Australian National University (ANU) Research School of Physics.
The team, led by ANU and RMIT University, successfully generated two types of diamonds: the kind found in fine jewelry and another called Lonsdaleite, which is found in nature at the site of meteorite impacts, such as Canyon Diablo in the US.
One of the lead researchers, ANU Professor Jodie Bradby, said their breakthrough shows that Superman may have had a similar trick up his sleeve when he crushed coal into diamond, without using his heat ray.
While Superman crushed carbon using the palm of his hand, the scientists used a specially designed anvil at room temperature.
Until now, lab-grown diamonds have been created by mimicking both the intense heat and extreme pressure present deep within the Earth.
“The twist in the story is how we apply the pressure,” Bradby said. “As well as very high pressures, we allow the carbon to also experience something called ‘shear’ – which is like a twisting or sliding force. We think this allows the carbon atoms to move into place and form Lonsdaleite and regular diamond.”
While mined diamonds are cubic in shape, the diamonds generated by the scientists are hexagonal, which led them to theorize that their varieties will be even harder than conventional diamonds.
Co-lead researcher Professor Dougal McCulloch and his team at RMIT used advanced electron microscopy techniques to capture snapshots of how the Lonsdaleite and regular diamonds formed.
“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 said.
The scientists believe that their new lab-grown, super-hard diamonds would likely be used for industrial purposes, such as drill bits and other cutting devices. Their findings were recently published in the scientific journal, Small.
Credits: ANU PhD scholar Xingshuo Huang holds the diamond anvil that the team used to make the diamonds in the lab. Photo by Jamie Kidston, ANU; River of diamonds image by RMIT; PhD scholar Brenton Cook (left) and Prof Dougal McCulloch with one of the electron microscopes used in the research. Image by RMIT.