Preparation of crystalline carbon nitride bulk samples

Summary form only given, as follows. A new method was developed for the preparation of bulk samples of carbon nitride on exposure of an amorphous nitrogen- and carbon-containing material to high temperature and ultrahigh pressure in the presence of crystallization seeds. Amorphous carbon nitride whose composition was close to C/sub 3/N/sub 4/ was used as a starting material. Thin films of crystalline carbon nitrides prepared by the laser-electric discharge method were used as crystallization seeds. The samples were evaluated by X-ray photoelectron spectroscopy (XPS), infrared spectroscopy, Auger electron spectroscopy scanning electron microscopy and X-ray diffraction. Notably, XPS studies of the samples demonstrate that the nitrogen composition in /spl alpha/-C/sub 3/N/sub 4/ material initially containing more than 58% nitrogen decreases during the thermobaric process and reaches a common, stable composition of 45%. The thermobaric experiments were performed at 10-77 kbar and 350-1200/spl deg/C.