2 - Atomic and Crystal Structures of Diamond

Abstract

This chapter explains the atomic and crystal structures of diamond. An inclusive understanding of diamond nucleation and growth processes during chemical vapor deposition (CVD) necessitates knowledge of atomic and crystal structures of diamond, as well as of the competing crystallites or amorphous phases that may be produced by CVD. Three hybrid carbon orbitals available for bonding—sp, sp2, and sp3—complete the series of electronic building blocks of all carbon allotropes and compounds. Diamond has two basic crystal structures, one with a cubic symmetry (more common and stable) and the other with a hexagonal symmetry (rare but well established, found in nature as the mineral lonsdaleite). The cubic structure is the dominant crystal structure in both natural and synthetic diamond since the staggered conformation is more stable than the eclipsed due to the slightly lower energy. Diamond polytypes and carbyne phases form only during the homogeneous nucleation and growth of diamond powder.