Synthetics made in a few minutes in the laboratory at room temperature

Applying pressure equivalent to 640 African elephants balancing on the toe of a ballet shoe enabled an international team of researchers to create synthetic diamonds in a room-temperature laboratory in minutes.

The feat is a serious departure not only from the formation of natural diamonds, which typically takes billions of years and occurs deep in the earth at temperatures above 1000 ° C, but also from the more traditional processes required to produce diamonds in the laboratory (that is high pressure, high temperature [HPHT] or chemical vapor deposition [CVD]).

Led by researchers from the Australian National University (ANU) and RMIT University, the scientists created two types of diamonds: one traditionally used in jewelry and Lonsdaleite, which occurs naturally at the site of meteorite impacts, such as Canyon Diablo. of Arizona.

Although the team previously created Lonsdaleite, this was only achieved by working at high temperatures; the new “unexpected” discovery, ANU says, shows that these diamonds can form even at normal ambient temperatures by applying only high pressure.

“The turning point in history is how we apply the pressure,” says Jodie Bradby, PhD, professor at the ANU Research School of Physics. “In addition to very high pressures, we allow the carbon to experience something called ‘shear’, which is like a twisting or sliding force. We believe this allows the carbon atoms to move into position and form the Lonsdaleite and the normal diamond. “

“Normal” diamonds, the researchers say, form in the veins of Lonsdaleite. They were identified through advanced electron microscopy techniques used by co-lead researcher Dougal McCulloch, PhD, and his RMIT team.

“Our images showed the regular diamonds forming only in the middle of these Lonsdaleite veins with this new method developed by our interinstitutional team,” he says.

“Seeing these little ‘rivers’ of Lonsdaleite and regular diamonds for the first time was just amazing and really helps us understand how they could form.”

Lonsdaleite has a different crystal structure than regular diamond and is expected to be 58% harder, the researchers say.

“Lonsdaleite has the potential to be used to cut ultra-solid materials in mining sites,” says Bradby.

“Creating more of this rare but super useful diamond is the long-term goal of this work.”

The results were published in the journal Small.