handbook of carbon, graphite, diamond and fullerenes

44 Carbon, Graphite, Diamond, and Fullerenes
As a reminder and as mentioned in Ch. 1, the term "carbon" by itself
should describe the element and nothing else. To describe a material, it is
coupled with a qualifier, such as "carbon black," "activated carbon,"
"vitreous carbon," "amorphous carbon," and others.
1.2 Structure of the Graphite Crystal
Graphite is composed of series of stacked parallel layer planes shown
schematically in Fig. 3.1, with the trigonal sp 2 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.
(5 atoms (in open circles)
have no direct neighbors
in adjacent planes
A Plane
B Plane
A Plane
Outline of
unit cell
a atoms (in full circles) have
neighbors directly above
and below In adjacent planes
Layer Plane c
,+ QJ spacing (V~)
Figure 3.1. Crystal structure of graphite showing ABAB stacking seq uence and unit
cell.