Common types of diamond
Sherry Huang
www.boreway.net
2016-01-15 16:48:24
graphite
Diamond and graphite are not the same kind of material, they are allotrope of the same elements. The difference is that the physical structurefeature. Both chemical formula is C.
Graphite atoms hexagonal planar structure, flaky; between diamond atom is a perspective view of a regular tetrahedron structure.
The melting point of diamond is 3550 ℃, the graphite melting point is 3652 ℃ ~ 3697 ℃ (sublimation). Graphite melting point higher than diamond.
From the point of view of internal lamellar graphite atomic crystals; from between the sheets, the graphite is a molecular crystal(Overall, the graphite should be mixed crystal); And the diamond is atomic crystal. But higher than the melting point of graphite crystal diamond, it seems incredible, but the covalent crystal lamellar graphite bond length is 1.42 × 10-10m, within the diamond crystal covalent bond length is 1.55 × 10-10m. With a covalent bond, bond length is smaller, the greater the bond energy, the stronger the bond, the more difficult it will destroy it, there is a need to provide more energy, and therefore should be higher melting point. (Mainly atomic crystal properties of graphite leads to its melting point becomes high)
man made rock
Synthetic diamond, there are two main methods, high-temperature and high-pressure chemical vapor deposition method.
HPHT method technology has been very mature, and the formation of industry. High domestic production, the highest in the world.
Chemical vapor deposition is still mainly present in the laboratory.
Carbon dioxide becomes diamond reversal: A domestic unit had declared at a low temperature of 440 degrees to achieve this change, however, once the relevant papers have been published that is strongly questioned his country's experts in related fields, and there is the phenomenon of the paper manuscript to throw, text data is also a serious wrong. Although the relevant staff in relevant academic journals were answering questions, this research is still being questioned is the scientific fraud is another case. But in the end nothing.
The emergence of nanomaterials caused world physicists, chemists, materials scientists and engineering, industry wide attention of new materials. This paper Continuity of nanomaterials, the basic nature of the diamond, the nature and prospects nanodiamonds, coalescence mechanism and nature of the PCD sintered nano elaborated, suggesting dual characteristics of nano polycrystalline diamond having a diamond nanomaterials proposed manufacturing possibilities of nano polycrystalline diamond.
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The nature of nanomaterials - nanosubstance show why these bizarre performance, mainly due to the material into nanoscale physical effects after showing some of the macro does not have the substance or substances in the macro negligible. According to PeopleNanoparticlesThe study, these effects are mainly surface effect, quantum size effectSmall size effect, macroscopic quantum tunneling effectWait.
