Preparation And Characterization Of Carbon And Nitrogen Compounds

In recent years, a great deal of theoreticians and experimenters has been directed toward developing carbon nitrides. Carbon nitrides may have many valuable merits, such as low coefficient of friction, light mass, high thermal conductivity, high thermal stability, oxidation resistance, chemical inertness. Among postulated carbon nitrides, β- C₃N₄, as a novel material, has high potential to fit demands for a variety of applications. Its hardness may rival or even exceed that of diamond.The work reported here had been directed toward the synthesis of carbon nitrides, specifically by using molecular precursors and by exploring solid-state and solvothermal methods to prepare extended carbon-nitrogen solids with the desired atomic ratio of C to N equal to 3:4, i.e. C₃N₄ under relatively mild conditions.In a solid-state synthesis, yellow brown C-N compounds in the temperature range of 500 -700℃ was obtained. The expected reaction was expressed as:2C₃N₆H₆ + C₃N₃Cl₃ (?) 3C₃N₄+3NH₄CIIn a solvothermal synthesis, carbon tetrachloride (CCl₄) was used as solvent. Melamine (C₃N₆H₆) and cyanuric chloride (C₃N₃Cl₃) acted as reactants. The desired reaction can be described as: 2 C₃N₆H₆ + C₃N₃Cl₃ (?) 3 C3N4 + 3 NH₄Cl,4NH₄Cl + 3CCl₄ (?) C₃N₄+16HCIThe reaction was performed at temperature 250℃ and lasted 12 hours, resulting in amorphous graphitic carbon nitride: a C-N compound, which contains a little H element. Hereto, its structure has not been resolved unambiguously.Thermal gravimetry / differential thermal analysis (TG/DTA) was employed to follow one of the solid state reactions. Products obtained from the above experiments were characterized by X-ray diffraction (XRD), Infrared spectroscopy (IR), elemental analysis and TEM.