Structure of hybrid carbon phases formed from the hexagonal graphene

M. I. Tingayev ; E. A. Belenkov

Čelâbinskij fiziko-matematičeskij žurnal, Tome 3 (2018) no. 4, pp. 486-497

Résumé

As a result of the theoretical analysis of the formation of sp${}^2$ + sp${}^3$ hybrid carbon phases structures on the basis of the hexagonal graphene layers, it is established that eight basic structural types of such compounds can be formed. In these polymorphic varieties all three- and four-coordinated atoms are in equivalent structural positions. The structure of the new carbon phases has been geometrically optimized by molecular mechanics MM+. As a result of the performed calculations, the structural parameters of hybrid phases were found. The crystal lattice of the phases belong to the hexagonal, orthorhombic, monoclinic or triclinic symmetry. Their elementary cells contain 6, 12 or 18 atoms. Phase density varies from 2.97 to 3.65 g/cm${}^3$. In six phases, the number of sp${}^3$ hybridized atoms is twice as large as the number of atoms in the state of sp${}^2$ hybridization, and in the other two phases, on the contrary, sp${}^2$ atoms are twice as large as sp${}^3$. The values of the lengths of interatomic bonds and the angles between them differ from the values typical for both graphite and diamond. The values of deformation parameters characterize the degree of difference between the structural states of atoms in hybrid phases and the states in graphite and diamond are minimal for the phases L${}_6$a7 and L${}_6$a8.

Détail

Keywords: graphene, hybridization, computer simulation, polymorphism, crystal structure.