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Diamond is extremely strong owing to its crystal structure, known as diamond cubic, in which each carbon atom has four neighbors covalently bonded to it. Bulk cubic boron nitride (c-BN) is nearly as hard as diamond. Diamond reacts with some materials, such as steel, and c-BN wears less when cutting or abrading such material. [4]
Above the graphite–diamond–liquid carbon triple point, the melting point of diamond increases slowly with increasing pressure; but at pressures of hundreds of GPa, it decreases. [14] At high pressures, silicon and germanium have a BC8 body-centered cubic crystal structure, and a similar structure is predicted for carbon at high pressures.
In 2001, a diamond-like-structured c-BC 2 N was synthesized at pressures >18 GPa and temperatures >2,200 K by a direct solid-state phase transition of graphite-like (BN) 0.48 C 0.52. The reported Vickers and Knoop hardnesses were intermediate between diamond and c-BN, making the new phase the second hardest known material. [39]
Diamond is the ultimate abrasive, but graphite is soft and is a very good lubricant. Diamond is an excellent electrical insulator, but graphite is an excellent conductor. Diamond is an excellent thermal conductor, but some forms of graphite are used for thermal insulation (for example heat shields and firebreaks).
“The energy needed to grow lab-grown [diamonds] is enormous, so your lab-grown diamonds are only as clean as that energy source.” There have been ethical issues with diamond mining in the past.
Last year, revenue from sales of its lab-grown diamonds reached 265 million Danish Krone ($38.5 million) and by 2026 the Danish retailer is aiming to bring in the billions. ... “So it comes back ...
Diamond industry researcher Edahn Golan says diamonds became associated with love and engagements around the 15th century, but it wasn't just a romantic gesture. Almost 9 in 10 engagement rings ...
Melting point: High, since melting means breaking covalent bonds (rather than merely overcoming weaker intermolecular forces). [ 5 ] Solid-phase electrical conductivity : Variable, [ 6 ] depending on the nature of the bonding: network solids in which all electrons are used for sigma bonds (e.g. diamond, quartz) are poor conductors, as there are ...