Graphene crystal structure

Figure 3. Left schematic drawing of the crystal structure of hexagonal graphite showing the AB graphene basal plane surface...

Figure 9.2 shows the crystal structure of graphene and its reciprocal lattice. Each unit cell, indicated in shade, contains two carbon atoms, A and B. The two unit vectors, ai and ai, are also shown. For multilayer graphene or graphite, the Bernal... 

Amorphous carbon is characterized by a highly imperfect structure and high reactivity. This shows by a considerable amount of mobile carbon atoms at a surprisingly low temperature. Besides, a vast number of defects and small sizes of graphene sheets make the carbon matrix very labile. As a result, it may be deformed under the action of adsorbates. For example, granules of amorphous carbon swell [88,89] in water with concomitant changes in the carbon substructure and porosity [90,91]. These properties of the support weaken rapidly as its crystal structure becomes more perfect. The labile structure of amorphous carbon is responsible for at least two mechanisms of blocking of the surface of supported metal particles. 

The crystal structure of graphene illustrates two important characteristics of crystals. First, we see that no atoms lie on the lattice points. While most of the structures we discuss in this chapter do have atoms on the lattice points, there are many examples, like graphene, where this is not the case. Thus, to build up a structure you must know the location and orientation of the atoms in the motif with respect to the lattice points. Second, we see that bonds can be formed between atoms in neighboring unit cells. This happens in many crystals, particularly metallic, ionic, and network-covalent solids. 

Fig. 1 Schematic representations of the crystal structures of (a) graphene and (b) graphane/ (Reproduced with permission).

Fig. 2 Fluorographene (a) Crystal structure - the light and dark spheres represent the fluorine and carbon atoms respectively, (b) Vials of fluorographene (left) and graphene (right) suspended in ethanol (Reprinted with permission. Copyright 2011...

Since hBN and graphene have similar crystal structures, their mono-layers are thought to have similar mechanical properties. The in-plane elastic rigidity is of a hBN sheet has been calculated to be in the range... 

There are two kinds of crystal structures in graphite the hexagonal structure and the rhombohedral structure. The hexagonal structure consists of graphene sheets... 

Fig. 8 (Colour online) Raman spectra of pristine graphene (spectrum 1) and graphane (spectrum 2) deposited on a substrate (a) and suspended (b). The D peak is activated by the binding event. Its intensity increases for increasing hydrogen content. The reaction with hydrogen is reversible, so that the D peak almost disappears after annealing of the sample (spectrum 3). c) Schematic representation of the crystal structure of graphene and d) theoretically predicted graphane. Adapted from Ref. 74.

FIGURE 1.11 (a) Schematic illustration of ideal crystal structure as well as the unit cell of graphene, (b)... 

These n interactions can be equally critical in materials chemistry applications, including self-assembled supramolecular architectures.For example, molecular wires can be formed from stacks of aromatic macrocycles.The binding of small molecules to carbon nanotubes and attraction between graphene sheets are both determined by noncovalent n interactions. The crystal structure and charge-transport properties of 7t-conjugated organic materials are also largely determined by n-n interactions. ... 

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