Graphite axial orientation

In this chapter, the structures and textures of carbons at different scales are explained. The carbon materials are classified into four families, diamond, graphite, fullerene, and carbyne on the basis of hybridized sp3, flat sp2, curved sp2, and sp orbitals used, respectively. Each family has its own characteristic diversity in structure and also in the possibility of accepting foreign species. The formation of these carbon materials from organic precursors (carbonization) is shortly described by dividing the process into three phases (gas, solid, and liquid), based on the intermediate phases formed during carbonization. The importance of nanotexture, mainly due to the preferred orientation of the anisotropic BSU in the graphite family, i.e., planar, axial, point, and random orientation schemes, is particularly emphasized. 

Sliding between concentric multiwalled carbon nanotubes presents a simple geometry, which restricts interlayer motion to a single (axial) direction with a fixed interlayer orientation of stiff, smooth layers. Each layer in a concentric multiwalled carbon nanotube is indexed by two integers (n, m) that give the circumference in graphitic lattice coordinates. The difference in radii between successive layers frustrates the circumferential interlayer registry. The axial... 

Figure 46. Phase diagram of N2 on graphite based on adiabatic heat capacity data coverage is reported in units of the complete n/S monolayer. Orientationally ordered commensurate phase (CO), orientationally disordered commensurate phase (CD), orientationally ordered uniaxially compressed incommensurate phase (UIO), orientationally disordered uni-axially compressed incommensurate phase (UID), triangular compressed incommensurate phase (TI), fluid phase (F), speculative reentrant fluid phase (RF). The measurement path for the highest coverage in Fig. 45 is sketched by the dashed line. (Adapted from Fig. 10 of Ref. 156.)...

Crucial information on the helical senses and morphologies of the HPMCs was obtained from the AFM images of poly-(f )-2/Ba and poly-(f )-2/Ag on highly oriented pyrolytic graphite (HOPG). Results were in full agreement with those previously obtained from CD, confirming the presence of the two enantiomeric axial chiralities. 

Carbon materials can also be classified in other ways, such as stacking methods, crystallinity, and structural symmetry. From the viewpoint of crystallinity, carbons can be classified as crystalline or amorphous. From the point of view of stacking methods, carbon structures can be classified as graphite, glassy carbon, carbon fiber, and carbon black. From the point of view of symmetry of the microstructure, carbons can be classified as randomly orientated or having point symmetry, axial symmetry, or planar symmetry (Figure 7.3) [2]. 

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