Synthesis of carbon nitride crystals at high pressures and temperatures

Carbon nitride crystals have been synthesized from C3N4H4 in the presence o f a nickel-based alloy or cobalt as a catalyst at high pressure of 7 GPa an d temperature of about 1400 degrees C. Scanning electron microscopy showed rod-like, well-faceted crystals with size of several micrometers, and the N content in these carbon nitride crystals was 47-62%, X-ray diffraction ind icated the crystals were composed of alpha-C3N4 and beta-C3N4. The experime ntal lattice constants of alpha-C3N4 (a = 6.425 Angstrom, c = 4.715 Angstro m) and beta-C3N4 (a = 6.419 Angstrom, c = 2.425 Angstrom) agree with ab ini tio calculations very well.