High pressure Raman and neutron scattering study on structure of carbon black particles

High pressure Raman and neutron scattering study of carbon blacks and highl y oriented pyrolytic graphite is reported. It is found that carbon black pa rticles are composed of graphitic nanocrystallites and amorphous carbon. Pr essure-induced order in inter-atomic distances within nanocrystallites is c ompletely reversible. Relative concentration of amorphous carbon decreases slightly with increased pressure. This process differs from temperature ind uced transformation of amorphous carbon into ordered carbon. Post-productio n treatment at high temperatures results in lateral and vertical growth of graphitic crystallites, and at sufficiently high temperatures almost all am orphous carbon is transformed into graphitic structures. Within the pressur e range under study, 5 GPa, only a small fraction of amorphous carbon is tr ansformed into ordered structures Pressure induced frequency shift of the E -2g bands of various carbon blacks is explained in terms of a modified inte rmolecular potential. (C) 2000 Elsevier Science Ltd. All rights reserved.