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 Å, b = 11.5 Å, c = 2.801 Å and β = 96°. 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 α- and β-C3N4 as well as a recently identified new tetragonal CN phase (with lattice constants of a = 5.65 Å and c = 2.75 Å). Transmission electron microscopy and scanning electron microscopy images show that most of the monoclinic CN grains 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.