Syntheses of Sublimable Carbon Nitride Materials

Abstract

Several potential synthesis routes to C₃N₄ were reinvestigated. These include thermal decomposition of Hg(SCN)₂, thermal decomposition of CuSCN, and thermal deammonation of melamine. The C₃N₄ material (1) obtained from Hg(SCN)₂ contained Hg, S, and H as impurities, and the material (2) obtained from decomposition of CuSCN is contaminated with S and H. Both C₃N₄ products were sublimed under dynamic vacuum at 700°C with a yield of about 40 %, affording la and 2a respectively. The sublimates were purer than the starting materials, and a mass spectrum of the vapor showed the presence of molecular C₃N₄. Melamine could not be fully deammonated to C₃N₄ by thermolysis. Product 2a had a hardness of 6.2 GPa and a Youngs modulus of 29.8 GPa, and showed a rather high elastic recovery of 81% during microindentation.