Multicomponent-Multiphase Equation of State for Carbon

Abstract

The unique properties of carbon have made it both a fascinating and an important subject of experimental and theoretical studies for many years [1]-[4]. The contrast between its best-known elemental forms, graphite and diamond, is particularly striking. Graphite is black, has a rather low density and high compressibility (close to that of magnesium), and is greasy enough to be useful as a lubricant and in pencil leads. Diamond is brilliantly translucent, 60% more dense than graphite, less compressible than either tungsten or corundum, and its hardness makes it useful for polishing and cutting. This variability in properties, as well as that observed among the many classes of carbon compounds, arises because of profound differences in electronic structure of the carbon bonds [5]. A number of other solid forms of carbon are known. Pyrolytic graphite [6] is a polycrystalline material in which the individual crystallites have a structure quite similar to that of natural graphite. Fullerite (solid C 60), discovered only ten years ago [7], consists of giant molecules in which the atoms are arranged into pentagons and hexagons on the surface of a spherical cage. Amorphous carbon [8][9], including carbon black and ordinary soot, is a disordered form of graphitemore » in which the hexagonally bonded layers are randomly oriented. Glassy carbons [9][10], on the other hand, have more random structures. Many other structures have been discussed [1][9].« less