General Considerations and Terminology

Graphite is remarkable for the large variety of materials that can be produced from its basic form such as extremely strong fibers, easily sheared lubricants, gas-tight barriers, and gas adsorbers. All these diverse materials have one characteristic in common they are all built upon the trigonal sp bonding of carbon atoms. 

As a reminder and as mentioned in Ch. 1, the term carbon by itseif shouid describe the eiement and nothing eise. To describe a material, it is coupled with a qualifier, such as carbon black, activated carbon, vitreous carbon, amorphous carbon, and others. 

Graphite is composed of series of stacked parallel layer planes shown schematically in Fig. 3.1, with the trigonal sp bonding described in Ch. 2, Sec. 4.0. In Fig. 3.1 (and subsequent figures of the carbon structure), the circles showing the position of the carbon atoms do not represent the actual size of the atom. Each atom, in fact, contacts its neighbors. 

Rgure3.1. Crystal structure ofgraphiteshoviringABAB stacking sequence and unit 

The spacing between the layer pleines is relatively large (0.335 nm) or more than twice the spacing between atoms within the basal plane and approximately twice the van der Waeils radius of ceirbon. The stacking of these layer planes occurs in two slightly different ways hexagoneil and rhombohedral. 

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