Identification of a new C-N phase with monoclinic structure

The crystal structure of a new monoclinic phase of a C-N compound was identified by both transmission electron microscopy and X-ray diffraction. The lattice parameters of the new C-N phase are a = 5.065 Angstrom, b = 11.5 Angstrom, c = 2.801 Angstrom and beta = 96 degrees. The monoclinic C-N grains were found in carbon-nitrogen films synthesized on Ni(100) substrates via bias-assisted hot filament chemical vapor deposition using a gas mixture of nitrogen and methane, together with alpha- and beta-C3N4 as well as a recently identified new tetragonal C-N phase (with lattice constants of a = 5.65 Angstrom and c = 2.75 Angstrom). Transmission electron microscopy and scanning electron microscopy images show that most of the monoclinic C-N grains bi exhibit irregular shapes. Energy dispersive X-ray analysis gives a relative N:C ratio of 0.5-1.0 in the monoclinic grain rich area. The stoichiometry and atomic arrangement of the monoclinic C-N phase should be determined further.