alpha beta Experimental evidence for alpha - and beta -phases of pure crystalline C3N4 in films deposited on nickel substrates

Abstract

Crystalline C N films have been synthesized on nickel (100) substrates via 3 4 hot-filament chemical vapour deposition using a gas mixture of nitrogen and methane activated by a bias. Scanning electron microscopy shows numerous perfect crystals and polycrystalline clusters. Energy-dispersive X-ray analysis and Auger electron microscopy give a relative nitrogen-to-carbon composition ratio of 1.30-1.40. X-ray diffraction and transmission electron microscopy indicate no amorphous material in the films, which are composed of alpha-C N, 3 4 beta-C N and an unknown C-N phase. The experimental lattice constants of 3 4 ( ( alpha-C N a = 6.38 A; c = 4.648 A) and beta-C N a = 6.24 A; c = 2.36 A) agree 3 4 3 4 with ab-initio calculations to within 1.3%and 2.5%respectively.