Carbon That Cracks Diamond

From News at Nature - Most Recent:

A new ultra-hard form of carbon may exist between graphite and diamond. Carbon can exist in a form halfway between graphite and diamond, say researchers in China and the United States. And they believe this stuff is as hard as diamond itself. Yanming Ma of Jilin University in Changchun, China, and his colleagues think that the new carbon material they have predicted in theoretical calculations1 may have been made already, in 2003. At that time, Ho-kwang Mao of the Carnegie Institution of Washington in Washington DC, a co-author on the current work, and his collaborators found that when they squeezed graphite in a diamond-toothed press, it formed a new material hard enough to crack the teeth2. But the researchers couldn't say for sure what form of carbon they had made. Ma and his co-workers now say that their hypothetical material has all the properties needed to explain the earlier results. Diamond is one of the two common crystal forms of pure carbon, the other being graphite. They could hardly be more different: one brilliantly transparent and ultra-hard, the other silvery black and soft.

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