New super-dense forms of carbon could outshine diamond

New Scientist : Three new stable carbon allotropes have been revealed by simulation, writes MacGregor Campbell for New Scientist. To find out whether forms of carbon denser than diamond might be possible, Artem Oganov of Stony Brook University in New York and colleagues simulated different configurations of carbon atoms at different temperatures and pressures. They found three that seemed to be stable enough to be made. While the three new allotropes are not as hard as diamond, their greater density would give them a higher refractive index and thus greater sparkle than diamond. Each of the three has unique band gaps, with one of them, tP12, having the largest band gap of any form of carbon; this variability makes them potential candidates for superconductors. It’s unclear as yet how the new materials could be made, although Oganov thinks that some of the unidentified, distinct carbon configurations produced by “shock compression” of graphite and amorphous carbon may be the newly described allotropes.