Structures of Diamondlike Phases

Diamondlike carbon phases consist of carbon atoms in which every atom forms four σ bonds with the neighboring atoms, as in the diamond structure. These phases can be divided into the following two groups: in the phases of the first group, all atoms have the same degree of hybridization (close to sp 3 ) and are located in crystallographically equivalent positions; in the phases of the second group, the hybridization states of atoms are also close to sp 3 but are crystallographically non� equivalent. The firstgroup phases are basic, and the number of these phases is limited. The secondgroup phases can be formed as a combination of the struc� tures of the firstgroup phas es, and the number of such combinations is very large and can hardly be classified. Therefore, we will restrict ourselves to considering the diamondlike phases of the first group.