The Australian National University (ANU) has led an international team to create a nano-sized diamond that's harder than the natural gem and which will be useful for cutting through super-hard mining materials.
ANU Associate Professor Jodie Bradby said her team, including ANU PhD student Thomas Shiell and experts from RMIT, the University of Sydney and the United States, fabricated nano-sized Lonsdaleite, which is a hexagonal diamond only found in nature at meteorite impact sites, such as in Arizona’s Canyon Diablo.
"This new diamond is not going to be on any engagement rings. You'll more likely find it on a mining site, but I still think that diamonds are a scientist's best friend,” said Assoc Prof Bradby from the ANU Research School of Physics and Engineering.
“Any time you need a super-hard material to cut something, this new diamond has the potential to do it more easily and more quickly.
"The hexagonal structure of this diamond's atoms makes it much harder than regular diamonds, which have a cubic structure.
“In the hexagonal shape, there is a two-step process to the deformation, which essentially results in the material being able to withstand much higher loads before deforming.
“The type of hexagonal diamond we have created consists of very small individual grains – only 10-20nm across – and nano-crystalline cubic diamonds are widely considered to be harder than larger cubic diamonds, following the ‘smaller is stronger’ rule for many materials.”
Using a diamond anvil, which squeezes two diamonds together at extreme pressure, the researchers created the diamond at just over 400 degrees Celsius, more than halving previous international attempts.
Assoc Prof Brady said that she and her team are keen to discuss the application of the technology with mining sector organisations.
“We are still in the lab stage, but we would hope that the hexagonal diamond could be made in sufficient quantities to replace cubic diamonds in terms of diamond-tipped bore drilling or any tools where cubic diamond is currently used by industry,” she said.
“If any companies are interested in investing in this technology, we would love to chat with them.”
Lonsdaleite is named after English crystallographer Dame Kathleen Lonsdale, who was the first woman elected as a Fellow to the Royal Society and the first woman president of the British Science Association.
Co-researcher Professor Dougal McCulloch from RMIT said that the success of the international project was due to the teamwork of world-leading scientists and cutting-edge technology.
"The discovery of the nano-crystalline hexagonal diamond was only made possible by close collaborative ties between leading physicists from Australia and overseas, and the team utilised state-of-the-art instrumentation, such as electron microscopes," he said.
Corresponding author Professor David McKenzie from the University of Sydney said he was doing the night shift in a United States laboratory when he noticed a little shoulder on the side of a peak in an X-ray diffraction pattern, which indicated that there was a hexagonal diamond in the sample.
"It didn't mean all that much until we examined it later on in Melbourne and in Canberra – and we realised that it was something very, very different,” he said.
The research is published in Scientific Reports.
Main image: Associate Professor Jodie Bradby, courtesy of the Australian National University (image by Jamie Kidston).
Thumbnail image: The diamond anvil used to make the nano-sized Lonsdaleite, courtesy of the Australian National University (image by Jamie Kidston).