The Crystal Structure of Diamond

Silicon has the crystal structure of diamond and its properties are influenced by the crystal orientation. ] CVD silicon can be... 

The element carbon occurs in nature in two so-called allotropic forms, different crystal structures with the same chemical formula. In Fig. 3.13 the crystal structure of diamond and graphite have been represented. In diamond the C atoms are closely packed and each C atom is linked with four other C atoms. Thus a tight network of atoms is formed which, together with the binding strength, is responsible for the extreme hardness of diamond. Graphite has a layered structure and the space between the layers is relatively large. 

The crystal structure of diamond. Each carbon atom is covalently bonded to four others. 

Can these large variations in stiffness be explained in terms of the stiffness of the chemical bonds within a material Qualit tatively, they can, although it is not just the stiffness of the individual bonds that is important, but how they are arranged. Take a diamond, for example. In the crystal structure of diamond each carbon atom is covalently bonded to four other carbon atoms, as illustrated for the central carbon atom in Figure 13-22 (some bonds on the other atoms are omitted for clarity of presentation). The... 

The crystal structure of diamond combined with the strong interatomic chemical bonding accounts for most of its unique properties. Although the properties of CVD diamond are slightly inferior to those of natural single crystal diamond (due to the presence of nondiamond... 

FIGURE 1.7. The crystal structure of diamond. Stereoview showing several unit cells. Each carbon atom is tetrahedrally surroimded by four others. The arrangement of carbon atoms found in cyclohexane and in tetramethylmethane (shown with black bonds) can also be picked out from this rigid structure,... 

The earliest demonstration of the regular tetrahedral arrangement of carbon bonds was provided by the analysis of the crystal structure of diamond. In this crystal... 

But, just as among the compounds of carbon, one can find among the minerals instances in which the skeleton is tightly cross-linked. Compare, for example, the crystal structure of diamond with that of cristobalite, one of the many structures adopted by silicon dioxide, whose more usual structure is quartz. As Fig. 9.10 shows, the silicon atoms occupy sites that form a diamondlike structure opened out by the bridging oxygen atoms. 

Figure 39.1 The crystal structure of diamond. The C-C distance is 1.54 A. The edge of the unit cell is 3.57 A.

---