7782-40-3

very hard crystals or light green powder

ChEBI: An allotropic form of the element carbon with cubic structure which is thermodynamically stable at pressures above 6 GPa at room temperature and metastable at atmospheric pressure. At low pressures diamond converts rapidly to graphite at temperatures above 1900 K in an inert atmosphere. The chemical bonding between the carbon atoms is covalent with sp3 hybridization.

Jewelry. Polishing, grinding, cutting glass, bearings for delicate instruments; manufacture of dies for tungsten wire and similar hard wires; making styli for recorder heads, long-lasting phonograph needles. In semiconductor research.

Exists in two major varieties: those bearing nitrogen as an impurity (Type I) and those without nitrogen (Type II). These two subgroups are further subdivided into Types Ia, Ib, IIa, and IIb. Type Ia diamonds are the most common type of naturally occurring diamond; they exhibit 0.1 to 0.2 wt.% nitrogen present in small aggregates, including platelets. By contrast, nitrogen in Type Ib diamonds is dispersed substitutionally. Of the two Type II diamond types, Type IIb is a semiconductor due to minute amounts of boron impurities and exhibits a blue color, whereas Type IIa diamonds are comparatively pure. Electric insulator (E = 7 eV.). Burns in oxygen.

Diamond nanopowder (DNPs) may be produced by multicathode direct current plasma chemical vapor deposition and high pressure high temperature (HPHT).
Potential uses of nano-diamond are in biosensor applications. Surface modification of nano-diamond may enhance its linking mechanism with specific biomolecules. DNPs can be subjected to functionalization post Fenton treatment. These functionalized DNPs may be used as gene delivery systems.

Diamond crystallographic structure consists to a face centered cubic crystal lattice where the carbon atoms occupy the eight corners, the centers of the six faces and half of the tetrahedral crystallographic sites (Z = 8). The most common crystal habits for euhedral crystals found in nature are the octahedron {111}, the cube {100}, and the dodecahedron {110} sometimes rounded due to etching. Diamond normally cleaves on the (111) plane but cleavage has been observed on the (110) plane and to a lesser extent some other crystallographic planes.