It takes nature aeons to make diamonds, as carbon in the earth crystallizes under intense pressure and heat. But chemists do it in nanoseconds. Using explosives to change the molecular structure of a carbon-metal powder, they produce industrial-grade diamonds used in drill bits and abrasives.
But the explosions are too fast for scientists to know exactly how diamonds are formed. Now, Lawrence Livermore National Laboratory physicists are studying the problem using a 60-foot-long compressed-gas gun--originally designed to simulate the effects of nuclear shock waves. A copper projectile is fired at up to 18,000 mph into a graphite target, compressing it into diamond that disintegrates a moment later. A detector measures the resulting shock wave, providing clues to the changes taking place.
Researchers are a long way from turning coal into diamonds. But understanding how such shock synthesis works could lead to better ways of making industrial diamonds.