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Synthetic
Diamond |
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| Synthetic
diamond is diamond produced through chemical or physical
processes in a laboratory. Like naturally occurring diamond
it is composed of a three-dimensional carbon crystal.
Synthetic diamonds are also called cultured diamonds,
manufactured diamonds, and artificial diamonds. |
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| History |
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| Synthetic
diamonds were first produced on February 16, 1953
in Stockholm, Sweden by the QUINTUS project of ASEA,
Sweden's major electrical manufacturing company
using a bulky apparatus designed by Baltzar von
Platen. Pressure was maintained within the device
at an estimated 83,000 atmospheres for an hour.
A few small crystals were produced. The discovery
was kept secret. |
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| Nevertheless,
General Electric researchers reported their own successful
diamond synthesis in Nature. The production of smaller
synthetic diamonds and especially diamond dust has become
an important industry with General Electric at the forefront.
General Electric, along with Sumitomo Electric and De
Beers marketed their synthetic stones as heat sinks for
electronics and used them solely for research purposes.
Significantly, the majority of these synthetic diamonds
are not of gem quality. |
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| As of
2004, two companies have introduced high-quality synthetic
diamonds to the general market. While
visiting Moscow in 1995 someone asked Carter Clarke
if he wanted to buy a diamond making machine. He brought
the machines and the scientists to Sarasota, Florida
and started the first diamond making company, Gemesis.
Gemesis grows diamonds in high-pressure, high-temperature
crystal growth chambers that resemble washing machines.
The device bathes a tiny sliver of natural diamond in
molten graphite at 1500 ºC and 58,000 atm. This
produces a 2.8-carat rough diamond which can be cut
to 1.5 carats. Gemesis diamonds have a yellow tint which
is rare in natural diamonds and therefore a valuable
aesthetic trait. The yellow tint occurs when less than
five out of each 100,000 carbon atoms in the diamond
crystal lattice are replaced with nitrogen atoms. Technically
it is a contaminant, but colored diamonds can still
be sold for more money because they can be made more
quickly, they cost less to manufacture, and they are
very popular. |
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| A second
company, Boston, Massachusetts based Apollo Diamond, uses
the low-pressure technique of chemical vapor deposition
(CVD) to produce larger, less expensive diamonds with
greater control over impurities. The diamond produced
is a single crystal, as opposed to the polycrystalline
patchworks formerly produced by CVD. This greater measure
of control allows Apollo Diamond to produce diamonds of
various colors, from pink to black. The ability to control
the intentional introduction of impurities, doping, is
necessary for the creation of diamond semiconductor devices.
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Uses
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| Given the extraordinary
set of physical properties diamonds exhibit, large, cheap
diamonds could have a wide ranging impact in many fields. |
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| The CVD produced
diamonds have been targeted for their potential use in
technology. For example, University of Wisconsin, Madison
chemistry professor Robert Hamers has developed a photochemical
methods for covalently linking DNA to the surface of polycrystalline
diamond films produced through CVD. Also, the diamonds
have been shown to detect redox reactions that can't ordinarily
be studied and in some cases degrade redox-reactive organic
contaminants in water supplies. |
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The
diamonds also have potential uses in the semiconductor
industry. This is because the diamonds can be "doped"
with impurities like boron and phosphorus. Since these
elements contain one more or one less electron than
carbon, they turn the diamonds into n-type or p-type
semiconductors. There are also studies being conducted
about impregnating boron-doped CVD diamonds with deuterium
yields to produce n-type semiconducing diamonds. |
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Both
types of diamonds mentioned above are visually indistinguishable
from the naturally occurring ones. However, the companies
have taken steps to ensure that they can be distinguished
by laser inscription, trace impurities, and infrared
and X-ray spectroscopy. The diamonds are being marketed
at $4,000 per carat, or roughly 30% less than the price
of a comparable natural diamond. The traditional diamond
industry is evaluating countermeasures to these cheaper
alternatives. (sources : Wired.com, Chemical and Engineering
News: The Many Facets of Man-Made Diamonds). |
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