Crystal structure of graphite

Fig. 7. Crystal structures of graphite, ordinary cubic diamond, and hexagonal diamond A, B, and C are the lateral positions.

The crystal structure of graphite and amorphous carbon is illustrated by the schematic representations given in Fig. 1. 

Fluorine. This application uses carbon plates as the anode in a fluorine salt solution. Since the ordered crystal structure of graphite results in short life, carbon is the preferred anode material (see Fluorine). 

Figure 7 shows the crystal structures of graphite, ordinary (cubic) diamond, and hexagonal diamond. The layers of carbon atoms lie in flat sheets in graphite, but in diamond the sheets are more wrinkled and lie closer together. Taken separately, the sheets are similar, but they may be stacked in various lateral positions and still have bonding between them. 

In a similar way Kekule s theory of the benzene structure has been very completely established by the whole development of aromatic chemistry. The direct physical verification of the presumably planar arrangement was in this case more delayed. The crystal structure of graphite was examined almost as soon as that of diamond, but the early results were inconclusive. The structure is not determined by the symmetry alone, and the later detailed investigation by Bernal (1924) showed that the carbon atoms in the hexagonal net must be coplanar to within at least 0-38 A. Later work by Ott (1928) narrowed this limit still further. Although it is generally assumed that the atoms are coplanar, the exactness with which this can be established depends on... 

Fig. 11. Crystal structure of graphite. The unit cell is shaded in green, (a) Top view of the surface layer. The hexagonal surface lattice is defined by two unit vectors u and v in the xy-plane with a length of 246 pm and an angle of 120° forming a honeycomb web of hexagonal rings. The basis of the lattice consists of two carbon atoms a, (white) and /3 (red) with a distance of 142 pm. (b) Perspective view, showing the layered structure. The distance between layers is 2.36 times the next-neighbor distance of atoms within one layer, and the bond between layers is weak. The a-atoms (white) are directly above an a-atom in the layer directly underneath at a distance of 334.8 pm the /3-atoms (red) are over hollow sites (h). The unit vector w is parallel to the z-axis with a length of 669.6pm.

The graphitized PPN exhibited a maximum conductivity of 8000 S/cm for HTT = 2800 C, much lower than that of HOPG (25000 S/cm), which can be explained in terms of the unique crystal structure of graphitized PPN. 

FIGURE 1.8. The crystal structure of graphite. This consists of hexagonal sheets of carbon atoms with weak forces between the sheets. Note that the arrangement of the carbon atoms in benzene (black bonds) is a portion of this structure. 

FIGURE 39.1 Crystal structure of graphite. (From Shobert, E.I. 1964. Carbon and Graphite. New York, Academic Press. With permission.)... 

Fig. 3.3 Crystal structures of graphite, hexagonal (upper) and rombohedral (below)...

The chemical crystal structure of graphite consists of condensed six-membered rings of carbon atoms forming planar layers. As shown in Fig. 5.3, these layers are stacked in a way that every third layer has an identical position to the first layer, resulting in a stacking sequence A, B A, B A, B etc. " This structure type represents the thermodynamically stable hexagonal crystal stracture. Besides, a... 

Intercalation of carbon fibers The crystal structure of graphite is of a kind that permits the formation of many compounds, called lamellar or intercalation compounds, by insertion of molecules or ions between the graphitic layers. 

Figure 5.15 a. Crystal structure of graphite crystal, b. Structure of turbostratic carbon. Source Reprinted from Hoffman WP, Hurley WC, Liu PM, Owens TW, The surface topology of non-shear treated pitch and PAN carbon fibers as viewed by STM, J Mater Res, 6,1685, 1991. 

Fig. 5.4 Crystal structures of graphite a, hexagonal diamond, or lonsdalite b and cubic diamond c, drawn to the same scale and showing unit ceUs...

Figure 39.1 The crystal structure of graphite. The separation of the sheets is 3.35 A. The C-C bond length in the sheets is 1.42 A.

It has been reasonably well established that the intercalation capacity of lithium and operating voltage of the lithium-ion battery depend on the properties of the SEI. The formation of the SEI, in turn, is strongly affected by the crystal structure of graphite. Successful development of negative electrodes for lithium-... 

FIGURE 6.15 The crystal structure of graphite. The C atoms form hexagonal rings as seen on the left. A unit cell is outlined and is shown alone on the right. 

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