The existence of the hard phase C3N4 carbon nitride is under dispute.
The conditions needed for high pressure/high temperature synthesis of
this hard phase include increasing the nitrogen content by using azide
s and the elimination of hydrogen from the starting material. Graphiti
c type CNx materials have been synthesized by a microwave nitrogen pla
sma CVD process. The material possesses turbostratic structure A = 2.6
0 Angstrom, C = 7.28 Angstrom and presumably has vacancies in the basa
l planes.