Synthesis and high-pressure behavior Of C6N9H3•HCI:: A graphitic material with a two-dimensional C-N network

A novel carbon nitride compound, with stoichiometry C6N9H4Cl and stucturally related to the proposed graphitic phase of C3N4, has been synthesized at moderate pressures in a bulk well-crystallized form. The new material was prepared through the polymerization of melamine based precursors in the presence of a liquid flux between 1.0-2.0 GPa and 500-550 degreesC in a piston cylinder device. Xray and electron diffraction measurements indicate a hexagonal space group (P6(3)/m) with cell parameters of a = 8.4379(10) Angstrom and c = 6.4296(2) Angstrom. The composition was determined by bulk chemical analysis and confirmed by electron energy loss spectroscopy. Our structure model is consistent with the infrared and C-13 NMR spectra. The cell parameters were obtained as a function of pressure to 34 GPa from, energy dispersive X-ray diffraction measurements. The compressional behavior of the carbon nitride material is highly anisotropic and similar to that of graphitic carbon.