High pressure crystal phase of carbon nitride

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 azides and the elimination of hydrogen from the starting material. Graphitic type CNx materials have been synthesized by a microwave nitrogen plasma CVD process. The material possesses turbostratic structure A = 2.60 Angstrom, C = 7.28 Angstrom and presumably has vacancies in the basal planes.