Graphitic Nanoparticles

Abstract

Pure carbon materials, graphite and diamond, possess a wide array of interesting physical properties, and so attract a large spectra of interests and applications. Carbon microparticles (carbon black) and carbon fibers are widely used in practical applications including common materials (paints, inks, polymers, etc.) and high-performance composite materials.Carbon displays a remarkably rich and complex chemical behavior (three different possible hybridizations: sp1, sp2, and sp3). In particular, the covalent carboncarbon bond is one of the strongest in nature, and induces a high melting temperature (> 4000°C). The phase changes associated with unusually high temperatures and pressures as revealed in the carbon phase diagram, and the fact that the solid sublimates at low pressures before melting, lead to many experimental difficulties in the study of high-temperature properties of carbon materials. Experiments must therefore rely on transient melting, for example, laser vaporization or arc-discharge heating. This explains why fullerenes and related graphitic structures have only recently been discovered.From a fundamental point of view, the discovery of fullerenes has introduced new ideas about how carbon atoms bond. The curvature and closure of graphitic surfaces has become a standard concept in carbon chemistry, and recently a wide range of structures formed by curved graphitic networks has been observed. A surprising aspect of fullerene research is that these novel graphitic structures were found in well-known experiments, and that they had been overlooked for so many years.This article will describe recent progress in the generation and physical characterization of graphitic nanoparticles, or multishell fullerenes. The lack of an efficient method for producing, as well as a method for purifying these particles makes it difficult to characterize them and to develop possible applications.