Diamond Cousin Proposed - Science News: Inspired by a television show about Egypt’s pyramids, Su calculated how to revamp the crystal structure of cubic diamond by exchanging each carbon atom with a pyramid of four carbon atoms. This arrangement should be 43 percent as dense and 65 percent as hard as diamond.
“It would be a very light, hard material, so you could imagine a large number of applications..."
“Even if it was synthesized, I don’t know if it would hold together,” says Wentzcovitch. Lower-energy structures tend to be more stable. “The energy of this stuff is much, much higher than other forms of carbon,” she says, “and little perturbations might cause the structure to collapse.”