Researchers at the Australian National University have developed a way to create a nano-crystalline hexagonal diamond that is harder than a jeweler's diamond.

Lonsdaleite is a hexagonal diamond named after famous crystallographer Dame Kathleen Lonsdale. In nature, this diamond is only found at meteorite impact sites such as Canyon Diablo in the United States. The discovery that lonsdaleite can be synthetically produced in a controlled laboratory setting presents a scientific breakthrough in terms of creating hexagonal diamonds.

Making the stronger diamond was a team led by associate professor Jodie Bradby and her colleagues from the ANU, University of Sydney, RMIT University, and the United States. The team also included ANU doctoral student Thomas Shiell.

In making lonsdaleite in the lab, the scientists used amorphous carbon as the basic material.

The research has been published in Scientific Reports.

Bradby, who teaches at the Research School of Physics and Engineering in ANU, said the lonsdaleite was made at 400 degrees Celsius, which is half the temperature normally required in making diamonds at laboratory settings.

Harder Than Regular Diamonds

Regular diamonds are cubic in structure, but the diamond that Bradby's team created in the lab was hexagonal.

"The hexagonal structure of this diamond's atoms makes it much harder than regular diamonds which have a cubic structure. We've been able to make it at the nanoscale and this is exciting because often with these materials 'smaller is stronger," Bradby said.

The hexagonal structure drew the interest of the team thanks to a little bump on one side of the data graph. The deviation was surmised to be the result of the different structure of the material.

Noting the synthetically made diamond took only half the temperature of previous efforts, Bradby said the structure was examined in the United States to see what goes on in the carbon material during compression.

The team examined the material with a machine that has a ring of X-rays spinning around at a speed "close to the speed of light," Bradby said. The team then fired a beam of X-ray through the glassy carbon material, which was under extreme pressure from two normal diamonds. The X-ray diffraction measurements allowed the researchers to study the structure of the material.

Usable At Mining Sites

However, Bradby remarked not to expect hexagonal diamonds too soon on engagement rings. The extra-hard material will find greater use in the mining sector, where it can be used for splicing materials.

"You'll more likely find it on a mining site - but I still think that diamonds are a scientist's best friend," she quipped.

Meanwhile, coresearcher Dougal McCulloch from RMIT hailed the collaboration of global experts in making the project a success and recalled how the researchers were able to utilize advanced instrumentation like electron microscopes for their experiments.

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