Formation of filamentous carbon from paraformaldehyde under high temperatures and pressures

Synthesis of filamentous carbon from paraformaldehyde by high-temperature, high-pressure treatment under "hydrothermal" conditions is reported. Deposition of carbon started at about 600 degrees C. Carbon filaments were grown at 650-750 degrees C. Raman and X-rap diffraction studies demonstrated the amorphous structure and sp(2) bonding of carbon in the filaments. Their length and thickness depended upon the experimental conditions. Well-ordered graphite was found at 800 degrees C. Thermodynamic calculations of the decomposition of formaldehyde under high temperatures and high pressures were also carried our. The results of the thermodynamic and experimental study are compared. (C) 1998 Elsevier Science Ltd. All rights reserved.