diamondcubic

Diamond cubic, also called the diamond lattice, is a crystal structure found in elemental carbon as diamond and in several group IV elements such as silicon and germanium. It consists of two interpenetrating face-centered cubic lattices with a four-atom basis, creating a three-dimensional tetrahedral network of covalently bonded atoms.

In the diamond cubic arrangement, each atom has four nearest neighbors at equal bond lengths, with bond angles close to the tetrahedral angle of 109.5 degrees. The conventional unit cell contains eight atoms, while the primitive cell contains two. The lattice constant is material dependent, for example about 3.567 angstroms for diamond and about 5.431 angstroms for silicon.

Properties arising from this structure include strong, directional covalent bonds that confer high hardness and high melting temperatures for diamond. Intrinsic diamond exhibits very low electrical conductivity, while silicon and germanium, sharing the same diamond cubic framework, are semiconductors with moderate band gaps suitable for electronics. The lattice also influences thermal conductivity, diffusion, and optical properties, contributing to diamond’s exceptional thermal performance and silicon’s well-established semiconductor behavior.

Occurrence and applications: the diamond cubic structure is the canonical form of elemental carbon in diamond and the primary crystal structure for silicon and germanium in the semiconductor industry. The arrangement underpins many industrial uses of diamond and silicon-based devices and serves as a standard model in crystallography and materials science.