Basal plane

Fig. XVII-18. Contours of constant adsorption energy for a krypton atom over the basal plane of graphite. The carbon atoms are at the centers of the dotted triangular regions. The rhombuses show the unit cells for the graphite lattice and for the commensurate adatom lattice. (From Ref. 8. Reprinted with permission from American Chemical Society, copyright 1993.)...

Kjems J K, Passell L, Taub H, Dash J G and Novaco A D 1976 Neutron scattering study of nitrogen adsorbed on basal plane-oriented graphite Rhys. Rev. B 13 1446-62... 

Fig. 6. Schematic illustration of stmctural relationships in quart2 where the circles represent siUcon centers only, projected on the basal plane (oxygen atoms are not shown) (Q) represent the highest level, ( ) represent the intermediate level, and (O) represent the lowest level. The lines are an aid to visuali2ation...

Property Value in basal plane Value across basal plane... 

The specific resistance of natural graphite crystals is ca Hem (room temperature) along the a axis parallel to the network basal plane. The resistance along the c axis (perpendicular to the basal plane) is ca 1 Q. The cja axis anisotropy ratio is, therefore, ca 10 . Screw dislocations within the crystal may short-circuit the current path parallel to the c axis and cause lower anisotropic ratios separation of planes may cause higher anisotropic ratios. 

The hardness on the basal plane of the cobalt depends on the orientation and extends between 70 and 250 HK. Cobalt is used in high temperature alloys of the superaHoy type because of its resistance to loss of properties when heated to faidy high temperatures. Cobalt also has good work-hardening characteristics, which contribute to the interest in its use in wear alloys. 

Especially at low temperatures, the thermal conductivity can often be markedly reduced by even small traces of impurities. This table, for the highest-purity specimens available, should thus be used with caution in apphcations with commercial materials. From Perry, Engineeiing Manual, 3d ed., McGraw-Hill, New York, 1976. A more detailed table appears as Section 5.5.6 in the Heat Exchanger Design Handbook, Hemisphere Pub. Corp., Washington, DC, 1983. f Parallel to basal plane. 

Figure 1.3 Surface morphology of AI2 O3 single erystal after evaporation in vaeuo at 2000° C. (a) the basal plane, and (b) a plane normal to the basal plane. Note the formation of ledges on the (0110) plane...

PAN fibers develop a structure with little point-to-point relationship between atoms in neighboring basal planes. This structure is labeled the turbostratic configuration and is characterized by interplanar spacing values greater than 0.344 nm. The crystallite size in the direction normal to the basal planes, or stack height (L, ), in turbostratic graphite is typically less than 5 nm. 

Fig. 2. Schematic representation of basal plane orientation in several types of carbon fibers. (A) Single crystal graphite. (B) ex-pitch carbon fiber. (C) ex-PAN carbon fiber, (D) VGCF.

The third term in Eq. 7, K, is the contribution to the basal plane thermal resistance due to defect scattering. Neutron irradiation causes various types of defects to be produced depending on the irradiation temperature. These defects are very effective in scattering phonons, even at flux levels which would be considered modest for most nuclear applications, and quickly dominate the other terms in Eq. 7. Several types of in-adiation-induced defects have been identified in graphite. For irradiation temperatures lower than 650°C, simple point defects in the form of vacancies or interstitials, along with small interstitial clusters, are the predominant defects. Moreover, at an irradiation temperatui-e near 150°C [17] the defect which dominates the thermal resistance is the lattice vacancy. 

A second study [33] on samples that contain a mixture of nanotubes, together with several percent buckyonion -type structures, was carried out at temperatures between 4.5 and 300 K, and fields between 0 and 5.5 T. The moment M is plotted as a function of field in Fig. 7, for the low-field range, and in Fig. 8 for the high-field range. The field dependence is clearly non-linear, unlike that of graphite, in which both the basal plane and the c-axis moments are linear in field, except for the pronounced de Flaas-van Alphen oscillations at low temperature. 

Fig. 4. Singularities in MWCNT imaged by means of basal plane lattice fringes, (a) Straight ideal MWCNT. (b) Capped MWCNT. The tube closes progressively by clusters of 2-5 graphene layers. (c)(d) Bamboo-like compartments in straight tubes.

---