PUTTING the squeeze on carbon dioxide can create a quartz-like crystal that
is nearly as hard as diamond, say scientists in California.
At normal temperatures and pressures, only weak van der Waal’s forces operate
between CO2 molecules. But a team from the Lawrence Livermore National
Laboratory has made crystals by compressing CO2to pressures of 40
gigapascals in a diamond anvil, and then heating it to 1800 kelvin with a laser.
Each atom of carbon formed bonds with four oxygen atoms—the structure
found in quartz, which is made of silicon and oxygen (Science, vol 283,
p 510).
Crystalline CO2 can exist at room temperature only at high
pressures. Though not as stable as diamond, says researcher Choong-Shik Yoo, the
new crystal has similar hardness.
