Crystal Structure of Graphite, Graphene and Silicon（晶体结构的石墨,石墨烯和硅）.pdfVIP

Crystal Structure of Graphite, Graphene and Silicon Dodd Gray, Adam McCaughan, Bhaskar Mookerji∗ 6.730—Physics for Solid State Applications (Dated: March 13, 2009) We analyze graphene and some of the carbon allotropes for which graphene sheets form the basis. The real-space and reciprocal crystalline structures are analyzed. Theoretical X-ray diffrac- tion (XRD) patterns are obtained from this analysis and compared with experimental results. We show that staggered two-dimensional hexagonal lattices of graphite have XRD patterns that differ significantly from silicon standards. ˚ The wide-variety of carbon allotropes and their associ- spacing between sheets c = 6.71A. The sheets align such ated physical properties are largely due to the flexibility that their two-dimensional hexagonal lattices are stag- of carbon’s valence electrons and resulting dimensionality gered, either in an ABAB pattern or an ABCABC pat- of its bonding structures. Amongst carbon-only systems, tern. The ABAB alignment is shown in Figure 1, which two-dimensional hexagonal sheets—graphene—forms of indicates four atoms per unit cell labeled A, B, A’, and the basis of other important carbon structures such as B’, respectively. The primed atoms A–B on one graphene graphite and carbon nanotubes. (:: Say something about layer are separated by half the orthogonal lattice spacing interesting band structure here) from the A’–B