Material Properties
A diamond is a transparent crystal of tetrahedrally bonded carbon atoms (sp3) that crystallizes into the diamond lattice which is a variation of the face centered cubic structure. Diamonds have been adapted for many uses because of the material's exceptional physical characteristics. Most notable are its extreme hardness and thermal conductivity (900–2,320 W·m−1·K−1), as well as wide band gap and high optical dispersion. Above1,700 °C (1,973 K / 3,583 °F) in vacuum or oxygen-free atmosphere, diamond converts to graphite; in air, transformation starts at ~700 °C. Diamond's ignition point is 720 - 800 °C in oxygen and 850 - 1,000 °C in air. Naturally occurring diamonds have a density ranging from 3.15–3.53 g/cm3, with pure diamond close to3.52 g/cm3. The chemical bonds that hold the carbon atoms in diamonds together are weaker than those in graphite. In diamonds, the bonds form an inflexible three-dimensional lattice, whereas in graphite, the atoms are tightly bonded into sheets, which can slide easily over one another, making the overall structure weaker.
