Synthesis of nanocrystalline nitrogen-rich carbon nitride powders at high pressure

Nitrogen-rich carbon nitride powders with composition close to C4N2.8-3.3 were synthesized by using a chemical reaction between sodium azide and hexachlorobenzene under high pressure (7.7 GPa) and a temperature of 500 degreesC for 30 min. The final black powders were relatively hard materials with high resistance to hot acids and common organic solvents. Analytical electron microscopy and X-ray diffraction studies showed that the powders are predominantly amorphous, containing nanometer-sized crystallites. Carbon and nitrogen K-edge structures obtained by electron energy-loss spectroscopy suggest the existence of chemical bonding between C and N, and that the amorphous carbon nitride matrix is primarily sp(2)-bonded. Raman and infrared features of the carbon nitride powders closely resemble those in carbon and diamond-like films and also characterize the powders as strongly disordered, sp(2)-bonded carbon nitride exhibiting graphite-like microdomains with dimensions of approximately 1 nm. (C) 2002 Elsevier Science B.V. All rights reserved.