Beta carbon nitride

This picture describes stable crystal lattice of this compound. Beta-C3N4 is material considered to be harder than diamond. Recently synthesized by milling graphite powder in NH3 atmosphere.

1. Synthesis of beta carbon nitride nanosized crystal through mechanochemical reaction.

Long-Wei Yin , Mu-Sen Li , Yu-Xian Liu , Jin-Ling Sui and Jing-Min Wang

2. http://en.wikipedia.org/wiki/Beta_carbon_nitride

3. Researchers may have spotted an elusive 'superhard' material between the layers of an atomic-scale sandwich, Philip Ball reports.