A laser built for nuclear weapons research has turned diamond into a metal.
Normally, a diamond is nothing like a metal, as its electrons cannot flow freely. However, scientists suspected that if you compress a diamond enough, it becomes metallic. But until recently, the technology to do this was not available. "Nobody had ever metallised diamond before," says Gilbert Collins of the Lawrence Livermore National Laboratory in California.
Now Collins and his colleagues have achieved the feat using the world's most powerful laser. The team focused several blue light beams from the Nova laser onto an aluminium target attached to a small diamond. The light's energy set up a shock wave that rippled through the metal and the diamond, which it compressed with a pressure of millions of atmospheres.
The diamond's surface began reflecting light, just like a metal would. "The shock waves compress the material into what we think is a metallic state," says Collins. The transition probably occurred when the diamond melted, loosening electrons so they could roam freely.
The highly pressurised carbon might be similar to the matter at the centres of dense stars such as white dwarfs, which form when Sun-like stars run out of fuel. By analysing the properties of melted diamond, these experiments might tell astronomers more about the conditions inside these dying stars.
Author: Charles Seife
New Scientist issue 3rd April 1999
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