β-Carbon nitride (beta-carbon nitride), β-C<sub>3</sub>N<sub>4</sub>, is a superhard material predicted to be harder than diamond.
The material was first proposed in 1985 by Amy Liu and Marvin L. Cohen. Examining the nature of crystalline bonds they theorised that carbon and nitrogen atoms could form a particularly short and strong bond in a stable crystal lattice in a ratio of 1:1.3, and that this material could be harder than diamond.
Nanosized crystals and nanorods of β-carbon nitride can be prepared by mechanochemical processing.
Production
Processing
β-C<sub>3</sub>N<sub>4</sub> can be synthesized in a mechanochemical reaction. This method involves ball milling of high-purity graphite powders down to an amorphous nanoscale size under an argon atmosphere. Then argon is replaced by an NH<sub>3</sub> gas atmosphere, which helps to form nanosized flake-like β-C<sub>3</sub>N<sub>4</sub>.