Moissanite ( ) is the name given to natural carbide silicon and its various crystalline polymorphs. It has the SiC chemical formula and is a rare mineral, discovered by the French chemist Henri Moissan in 1893. Silicon carbide is useful for commercial and industrial applications because of its hardness, optical properties and thermal conductivity. Efforts to synthesize silicon carbide in the laboratory began in the early 1900s.
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The Moissanite mineral was discovered by Henri Moissan while examining rock samples from a meteor crater located in Canyon Diablo, Arizona, in 1893. At first, he mistakenly identified the crystal as a diamond, but in 1904 he identified the crystals as silicon carbide. The artificial silicon carbide was synthesized in the laboratory by Edward G. Acheson just two years before the discovery of Moissan.
The silicon carbide mineral form is named Moissanite in honor of Moissan later in his life. Discoveries in the Diablo Canyon meteorite and other places are challenged for long periods of time as carborundum contamination from manmade abrasive devices.
Maps Moissanite
Geological events
Until the 1950s no other source, other than meteorites, had been found. Then Moissanite was found as an inclusion in a kimberlite from a diamond mine in Yakutia in 1959, and in the Green River Formation in Wyoming in 1958. The existence of Moissanite in nature was questioned even in 1986 by Charles Milton, an American geologist.
Moissanite, in its natural form, is very rare. It has been found only in small places from the upper mantle to the meteorite. The discovery has shown that Moissanite occurs naturally as an inclusion in diamonds, xenoliths, and ultramafic rocks such as kimberlite and lamproite. They have also been identified in carbon chondrite meteorites as presolar seeds.
Meteorite
Analysis of silicon carbide grains found in Murchison meteorites has revealed anomalous ratios of carbon and silicon anomalies, showing origin from outside the solar system. 99% of these silicon carbide granules come from around the giant carbon-asymptotic starch branches. Silicon carbides are usually found around these stars, as they are deduced from their infrared spectrum.
Source
All silicon carbide applications currently use synthetic materials, because natural materials are very rare.
Silicon carbide was first synthesized by JÃÆ'¶ns Jacob Berzelius, best known for his discovery of silicon. Years later, Edward Goodrich Acheson produces a viable mineral that can replace diamonds as abrasion and cutting material. This is possible, because moissanite is one of the most difficult substances known, with hardness under diamonds and comparable to those of boron nitride and boron nitride.
Pure synthetic moissanite can be prepared from thermal decomposition of preceramic poly (methylsilyne) polymers, requiring no binding matrix, for example. , cobalt metal powder.
Physical properties
The crystal structure is held together with strong covalent bonds similar to diamonds, allowing Moissanite to withstand high pressures up to 52.1 gigapascals. The colors vary greatly and are judged from the D to K range on the diamond gradation scale.
Apps
Moissanite was introduced to the jewelry market in 1998 after Charles & Colvard, formerly known as C3 Inc., received a patent to create and market lab-grown silicon carbide diamonds, becoming the first company to do so. Charles & amp; Currently Colvard manufactures and distributes moissanite jewelry and loose gems under the trademarks of Forever One, Forever Brilliant and Forever Classic. Other manufacturers market silicon carbide gemstones under trademark names such as Amora and Berzelian. Moissanite is considered an alternative to diamond, with some optical properties that exceed the diamond. Lower prices and less exploitative mining practices needed to get it make it a popular alternative to diamonds. Because of part of the similar thermal conductivity of Moissanite and diamonds, it is a popular target for fraud; However, higher electrical conductivity and the birefringence of Moissanite can alert buyers to fraud. In addition, thermochromism is exhibited in Moissanite, so gradual warming will cause it to change color starting at about 65 ° C (150 ° F). This color change can be a diagnostic to distinguish diamonds from Moissanite, although birefringence and the difference in electrical conductivity are a more practical diagnostic differentiator. On the scale of Mohs mineral hardness is 9.5, with diamond being 10. In many developed countries, the use of moissanite in jewelry is controlled by patents held by Charles & amp; Colvard; This patent expires in August 2015 for the United States, and in 2016 in most other countries except Mexico, where it will remain patentable until 2018.
Because of its hardness, it can be used in high pressure experiments, instead of diamonds (see diamond anvil cells). Because large diamonds are usually too expensive to use as a foundation, synthetic moissanite is more commonly used in large-volume experiments. Synthetic moissanite is also attractive for both electronic and thermal applications because its thermal conductivity is similar to diamonds. High silicon carbide electronic devices are expected to be used in the design of protection circuits used for motors, actuators, and energy storage or pulse power systems. It also shows thermoluminescence, making it useful in radiation dosimetry.
See also
- List of meteoritic words
- Engagement ring
- Fair trade
- Charles & amp; Colvard
- Diamond
- Cubic zirconia
References
Further reading
- Nassau, Kurt (1999). "Moissanite: new synthetic gemstone material" (PDF) . Journal of Gemmology . 26 (7): 425-438.
Source of the article : Wikipedia
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