Identification Of A New Tetragonal C-N Phase

A new tetragonal phase of C-N compound was identified by scanning and transmission electron microscopy and X-ray diffraction. The lattice parameters for the new C-N structure are a = 5.65 Angstrom and c = 2.75 Angstrom. The tetragonal C-N grains were found in the carbon-nitrogen films synthesized on Ni(1 0 0) substrates via bias-assisted chemical vapor deposition using a gas mixture of nitrogen and methane, together with alpha- and beta-C3N4, as well as other unknown C-N phases. Transmission electron microscopy and scanning electron microscopy images show that most of the tetragonal C-N grains have perfect single-crystalline tetrahedrons with different sizes, but some of them exhibit irregular shapes. Energy dispersive X-ray analysis gives a relative N:C of 0.8-1.0 in the tetrahedral-grain enriched films. The stoichiometry and atomic arrangement of the tetragonal C-N phase should be determined further.