The history of the diamond industry is rife with conflict, unregulated labor, and monopolies. Not only that but these sparkling gemstones require billions of years in the deep recesses of Earth under immense pressure and heat to be compressed before they are ready to be processed into jewelry or industrial machines – making gemstone-quality diamonds both rare and expensive.
As a result, scientists have been scrambling to find a viable method of creating diamonds in a lab that is cheaper, faster, and more ethical than traditional diamond-hunting.
"Natural diamonds are usually formed over billions of years, about 150 kilometers deep in the Earth where there are high pressures and temperatures above 1,000 degrees Celsius," said Professor Jodie Bradby from the ANU Research School of Physics in a statement.
Using a new method they describe in their study published in Small, the researchers synthesized two types of diamond: the regular type used for jewelry and a type of diamond called Lonsdaleite that theoretically is harder than cubic diamond but is only found in graphite meteorites.
To create the diamond, glassy carbon is compressed to extreme pressures. Glassy carbon is a form of carbon without crystals that, when compressed in diamond anvil cells, can form veins of diamond.
Diamond has been synthesized in labs since H. Tracy Hall achieved the first commercially successful synthesis in 1954, but the process is incredibly expensive and requires both intense pressure and extremely high temperatures. However, by changing how the pressure is applied, the researchers discovered that high temperatures may not be needed after all.
"The twist in the story is how we apply the pressure. 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," Professor Bradby said.
The process has not been demonstrated to produce significant quantities of diamond just yet. The results suggest both diamond and Lonsdaleite can be synthesized at room temperature, but more work must now be done to improve the process. Both materials are extremely useful in a variety of industries, from slicing through ultra-hard materials to biomedical applications that include sensing and drug delivery. If these could be produced in large enough quantities, it could have massive implications.
"Lonsdaleite has the potential to be used for cutting through ultra-solid materials on mining sites," Professor Bradby said.
"Creating more of this rare but super useful diamond is the long-term aim of this work."