Search results
Results from the WOW.Com Content Network
At standard temperature and pressure, 20 °C (293 K) and 1 standard atmosphere (0.10 MPa), the stable phase of carbon is graphite, but diamond is metastable and its rate of conversion to graphite is negligible. [7] However, at temperatures above about 4500 K, diamond rapidly converts to graphite.
At normal temperature and pressure, 20 °C (293 K) and 1 standard atmosphere (0.10 MPa), the stable phase of carbon is graphite, but diamond is metastable and its rate of conversion to graphite is negligible. [28] However, at temperatures above about 4500 K, diamond rapidly converts to graphite.
As an example, the conversion of a diamond into graphite is a spontaneous process at room temperature and pressure. Despite being spontaneous, this process does not occur since the energy to break the strong carbon-carbon bonds is larger than the release in free energy.
The slight decrease in covalency for B-N bonds compared to C-C bonds reduces the hardness from ~100 GPa for diamond down to 48 GPa in c-BN. As diamond is less stable than graphite, c-BN is less stable than h-BN, but the conversion rate between those forms is negligible at room temperature. [30]
The diamond was cut into a cushion shaped gem weighing 128.48 carats (25.696 g). For a long time, the Star of the South was considered to be "by far the largest diamond discovered by any woman anywhere", [11] until the Incomparable Diamond was discovered in the 1980s. The diamond has a color grade of Fancy Light Pinkish-Brown.
Tools. Tools. move to sidebar hide. ... one mole of a substance at a given combination of temperature and ... graphite: 717 [1] C diamond: 715 [1] Si silicon: 456 [1 ...
The conversion from diamond to graphite, however, has a very high activation energy and is therefore extremely slow. Despite the hardness of diamonds, the chemical bonds that hold the carbon atoms in diamonds together are actually weaker than those that hold together graphite. The difference is that in diamond, the bonds form an inflexible ...
Detonation nanodiamond (DND), also known as ultradispersed diamond (UDD), is diamond that originates from a detonation. When an oxygen-deficient explosive mixture of TNT / RDX is detonated in a closed chamber, diamond particles with a diameter of c. 5 nm are formed at the front of the detonation wave in the span of several microseconds.