Last Update: Thursday, February 26, 2004. 1:29pm (AEDT)
'Fake' diamonds prove harder than the real thing
Artificial diamonds made from gas have turned out to be surprisingly hard, harder even than natural diamonds, according to United States researchers.
The team at the Carnegie Institution's Geophysical Laboratory in Washington says the super-hard diamonds should be useful for industrial processes.
"We believe these results are major breakthroughs in our field," Chih-shiue Yan, who led the experiment, said in a statement.
"Not only were the diamonds so hard that they broke the measuring equipment, we were able to grow gem-sized crystals in about a day."
Writing in the online issue of Physica Status Solidi, Mr Yan and colleagues said they grew the crystals using a process called high-growth rate chemical vapour deposition.
In the process, hydrogen gas and methane are bombarded with charged particles, or plasma, in a chamber.
They subjected the crystals to high-pressure, high-temperature treatment to harden them further.
The diamonds were heated to 2,000 degrees Celsius and put under pressures between 50,000 and 70,000 times sea-level atmospheric pressure for 10 minutes.
The resulting diamonds were at least 50 per cent harder than natural diamonds, they found.
"This has opened up an entirely new way of producing diamond crystals for a variety of applications, such as the next generation diamond-based electronics devices and cutting tools," Carnegie's Russell Hemley said.
Real diamonds are made from carbon under pressure.