Diamond
Diamond is the second most stable form of carbon after graphite. Its hardness and high dispersion of light make it useful for industrial applications and jewelry. It is the hardest known mineral. Diamonds may be strong, but aggregated diamond nanorods called as amorphous fullerene are very strong. Amorphous fullerene has isothermal bulk modulus greater than that of diamond.
Diamond nanorods
Fabrication of diamond rods can be done by a variety of techniques. The rods can be grown epitaxially from the gas phase under low-pressure conditions on diamond seed crystals wetted with Ni, Fe, or Mn.
Single-crystalline diamond nanorods
Single-crystalline diamond nanorods can be synthesized by the hydrogen plasma post-treatment of multiwalled carbon nanotubes. The diamond nanorods are identified as having a core-sheath structure with the inner core being diamond crystal and the outer shell being composed of amorphous carbon. Single crystal diamond filaments can also be grown.
Aggregated diamond nanorods
A team from the Bayerisches Geoinstitut (Universität Bayreuth) has just reported the synthesis of these aggregated diamond nanorods (ADNR) and their remarkable properties. The researchers have made this material by subjecting carbon-60 molecules to immense pressures. The new form of carbon, which is known as aggregated diamond nanorods, which is harder than diamond has many industrial applications. ADNR material is the densest form of carbon and 11% less compressible than diamond. The combination of the hardness of the ADNR and its chemical stability makes it a potentially excellent material for machining ferrous materials.
Nanowhiskers
Diamond whiskers can be grown in an electron microscope on the sharp edges of diamond or other dielectric crystals under electron beam irradiation from carbon-containing residual gases at low pressures. Diamond whisker can be grown in a metal-carbon system at high pressure and temperature conditions. Aggregates of needle-like diamond crystals and particles with sharp edges of about 10 nm in size can be produced by a shock wave process. Also diamond nanowhiskers could potentially be produced by detonation synthesis.