Allotropes of carbon.pdf

Allotropes of carbon differentl differentlyy from its gem-grade counterpart. Industrial Industrial diamond amondss are value valuedd mostl mostlyy for thei theirr hardn hardness ess and heat heat conconductivity, making many of the  gemological  gemological   characteristics of diamond, including clarity and color, mostly irrelevant. evant. This helps explain explain why 80% of mined diamonds (equal to about 100 million carats or 20 tonnes annually) are unsuitable for use as gemstones and known as  bort , are destined for industrial use. In addition to mined diamonds, synthetic monds,  synthetic diamonds found diamonds  found industrial applications almost immediately after their invention in the 1950s; another 400 million carats (80 tonnes) of synthetic diamonds are produced annually for industrial use which is nearly four times the mass of natural diamonds mined over the same period. The dominant industrial use of diamond is in   cutting, cutting, drilling (drill bit bitss), ), grinding  grinding (diamon (diamondd edged edged cutters cutters), ), and polishi polishing. ng. Most uses of diamonds diamonds in these technol technoloogies do not require require large diamonds; diamonds; in fact, fact, most diamonds that are gem-quality can find an industrial use. Diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications applications (due to its extraordinary extraordinary hardness). Specialized applications include use in laboratories as containment for high pressure experiments (see diamond (see  diamond anvil), anvil), high-performance bearings bearings,, and limit limited ed use in speci speciali alized zed windows.. windows

Eight Eight allotr allotrope opess of   of   carbon: carbon: a)   diamond  , b)   graphite , c) lonsdaleite , d) C 6600   buckminsterfullerene , buckminsterfullerene , e) C 540 540 ,  Fullerite f) C 70  , g)  g)   amorphous carbon carbon ,  , and h) single-walled    carbon nan70 otube.. otube

Carbon is capable of forming many allotropes Carbon is many  allotropes due  due to its valency.. Well-known valency Well-known forms forms of carbon include diamond include diamond and  and   graphite. graphite. In recent recent decades decades many more allotrope allotropess and forms orms of carbon carbon have have been been disco discove vered red and resea researc rche hedd including ball shapes such as   buckminsterfullerene and sheets such as graphene as  graphene.. Larger scale scale structures structures of carbon include include nanotubes nanotubes,, nanobuds nanobuds and nanoribb nanoribbons. ons. Other Other unusual forms of carbon exist at very high temperature or extreme pressures.

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With the continuing advances being made in the production of synthetic diamond, future applications are beginning to become feasible. feasible. Garnering much excitement excitement is the possible use of diamond as a  semiconductor  semiconductor suitable  suitable to build microchips build microchips from,  from, or the use of diamond as a heat a heat sink in sink  in electronics  electronics.. Significant Significant research efforts efforts in Japan in  Japan,, Europe,, and the United Europe the  United States are States  are under way to capitalize on the potential offered by diamond’s unique material properties, combined with increased quality and quantity of supply starting to become available available from synthetic synthetic diamond manufacturers.

Diamo amond

Each carbon atom in a diamond is covalently bonded to four other carbons in a  a   tetrahedron. tetrahedron. These tetrahedron tetrahedronss together form a 3-dimensional network of six-membered Diamond  is a well known allotrope of carbon. The hard- carbon carbon rings rings (simil (similar ar to cyclohexane cyclohexane), ), in in the the chair conf confororness and high dispersion of light of diamond make it use- mation mation,, allowing for zero bond zero  bond angle  angle   strain. strain. This stable stable ful for both industrial applications and jewelry. Diamond network network of cova covalent lent bonds and hexa hexagon gonal al rings, rings, is the reareais the hardest known natural mineral natural  mineral.. This make makess it an son that diamond is so strong. excellent abrasive and makes it hold polish and luster extremely tremely well. No known naturally occurring occurring substance substance can cut (or even scratch) a diamond, except another diamond.

Main article: Diamond article:  Diamond

The market for industrial-grade diamonds operates much 1

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Graphite

AMORPHOUS CARBON 

planes, brittleness and inconsistent mechanical properties.

In its pure glassy (isotropic) synthetic forms,   pyrolytic graphite and carbon fiber graphite are extremely strong, heat-resistant (to 3000 °C) materials, used in reentry Graphite, named by Abraham Gottlob Werner in 1789, shields for missile nosecones, solid rocket engines, high from the Greek γράφειν ( graphein, “to draw/write”, for temperature reactors,   brake   shoes and   electric motor its use in pencils) is one of the most common allotropes brushes. of carbon. Unlike diamond, graphite is an electrical con- Intumescent or expandable graphites are used in fire seals, ductor. Thus, it can be used in, for instance, electrical arc fitted around the perimeter of a fire door. During a fire lamp electrodes. Likewise, under  standard conditions, the graphite intumesces (expands and chars) to resist fire graphite is the most stable form of carbon. Therefore, it is penetration and prevent the spread of fumes. A typical used in thermochemistry as the standard state for defining start expansion temperature (SET) is between 150 and the heat of formation of carbon compounds. 300 °C. Main article: Graphite

Graphite conducts electricity, due to delocalization of the pi bond electrons above and below the planes of the carbon atoms. These electrons are free to move, so are able to conduct electricity. However, the electricity is only conducted along the plane of the layers. In diamond, all four outer electrons of each carbon atom are 'localised' between the atoms in covalent bonding. The movement of electrons is restricted and diamond does not conduct an electric current. In graphite, each carbon atom uses only 3 of its 4 outer energy level electrons in covalently bonding to three other carbon atoms in a plane. Each carbon atom contributes one electron to a delocalised system of electrons that is also a part of the chemical bonding. The delocalised electrons are free to move throughout the plane. For this reason, graphite conducts electricity along the planes of carbon atoms, but does not conduct in a direction at right angles to the plane. Graphite powder is used as a dry lubricant. Although it might be thought that this industrially important property is due entirely to the loose interlamellar coupling between sheets in the structure, in fact in a  vacuum environment (such as in technologies for use in space), graphite was found to be a very poor lubricant. This fact led to the discovery that graphite’s lubricity is due to adsorbed air and water between the layers, unlike other layered dry lubricants such as molybdenum disulfide. Recent studies suggest that an effect called superlubricity can also account for this effect. When a large number of crystallographic defects bind these planes together, graphite loses its lubrication properties and becomes what is known as  pyrolytic carbon, a useful material in blood-contacting implants such as prosthetic heart valves.

Density: graphite’s specific gravity is 2.3, which makes it lighter than diamonds. Chemical activity: it is slightly more reactive than diamond. This is because the reactants are able to penetrate between the hexagonal layers of carbon atoms in graphite. It is unaffected by ordinary solvents, dilute acids, or fused alkalis. However, chromic acid oxidises it to carbon dioxide.

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Graphene

Main article: Graphene A single layer of graphite is called graphene and has extraordinary electrical, thermal, and physical properties. It can be produced by epitaxy on an insulating or conducting substrate or by mechanical exfoliation (repeated peeling) from graphite. Its applications may include replacing silicon in high-performance electronic devices.

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Amorphous carbon

Main article: Amorphous carbon Amorphous carbon  is the name used for   carbon  that

does not have any crystalline structure. As with all glassy materials, some short-range order can be observed, but Graphite is the most stable allotrope of carbon. Contrary there is no long-range pattern of atomic positions. While to popular belief, high-purity graphite does not readily entirely amorphous carbon can be produced, most amorburn, even at elevated temperatures. [1] For this reason, it phous carbon actually contains microscopic crystals of is used in nuclear reactors and for high-temperature cru- graphite-like,[3] or even diamond-like carbon.[4] cibles for melting metals.[2] At very high temperatures Coal and soot or carbon black are informally called amorand pressures (roughly 2000 °C and 5 GPa), it can be phous carbon. However, they are products of pyrolysis transformed into diamond. (the process of decomposing a substance by the action Natural and crystalline graphites are not often used in of heat), which does not produce true amorphous carbon pure form as structural materials due to their shear- under normal conditions.

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Nanocarbons Buckminsterfullerenes

Main article: Fullerenes The   buckminsterfullerenes , or usually just   fullerenes  or buckyballs for short, were discovered in 1985 by a team of scientists from Rice University and the University of Sussex, three of whom were awarded the 1996 Nobel Prize in Chemistry. They are named for the resemblance of their Computer models of stable nanobud structures  allotropic structure to the geodesic structures devised by the scientist and architect Richard Buckminster “Bucky” Fuller. Fullerenes are molecules of varying sizes com- fullerenes and carbon nanotubes. For instance, they have posed entirely of carbon, which take the form of a hollow been found to be exceptionally good field emitters. sphere, ellipsoid, or tube. As of the early twenty-first century, the chemical and physical properties of fullerenes are still under heavy study, in both pure and applied research labs. In April 2003, fullerenes were under study for potential medicinal use — binding specific antibiotics to the structure to target resistant bacteria and even target certain cancer cells such as melanoma.

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Glassy carbon

Carbon nanotubes

Main article: Carbon nanotube Carbon nanotubes, also called buckytubes, are cylindrical   carbon molecules  with novel properties that make them potentially useful in a wide variety of applications (e.g., nano-electronics,   optics,   materials   applications, etc.). They exhibit extraordinary strength, unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized. A nanotube is a member of the   fullerene   structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several centimeters in length. There are two main types of nanotubes:  single-walled nanotubes (SWNTs) and multiwalled nanotubes (MWNTs).

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Carbon nanobuds

Main article: Carbon nanobud

A large sample of glassy carbon.

Main article: Glassy carbon Glassy carbon or   vitreous carbon  is a class of non-

graphitizing  carbon widely used as an electrode material in electrochemistry, as well as for high-temperature crucibles and as a component of some prosthetic devices. It was first produced by Bernard Redfern in the mid1950s at the laboratories of The Carborundum Company, Manchester, UK. He hadset out to develop a polymer matrix to mirror a diamond structure and discovered a resole (phenolic) resin that would, with special preparation, set without a catalyst. Using this resin the first glassy carbon was produced.

The preparation of glassy carbon involves subjecting the organic precursors to a series of heat treatments at temCarbon nanobuds   are a newly discovered allotrope peratures up to 3000 °C. Unlike many non-graphitizing of   carbon   in which   fullerene   like “buds” are cova- carbons, they are impermeable to gases and are chemlently attached to the outer sidewalls of the  carbon nan- ically extremely inert, especially those prepared at very otubes. This hybrid material has useful properties of both high temperatures. It has been demonstrated that the

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rates of oxidation of certain glassy carbons in oxygen, carbon dioxide or water vapour are lower than those of any other carbon. They are also highly resistant to attack by acids. Thus, while normal  graphite is reduced to a powder by a mixture of concentrated sulfuric and nitric acids at room temperature, glassy carbon is unaffected by such treatment, even after several months.

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Atomic and diatomic carbon

Main articles: Atomic carbon and diatomic carbon Under certain conditions, carbon can be found in its atomic form. It is formed by passing large electric currents through carbon under very low pressures. It is extremely unstable, but it is an intermittent product used in the creation of carbenes.[5] Diatomic carbon can also be found under certain conditions. It is often detected via spectroscopy in extraterrestrial bodies, including comets and certain stars.[6][7]

OTHER POSSIBLE FORMS 

Ti3 AlC2 , Mo 2 C, etc. This synthesis is accomplished using chlorine treatment, hydrothermal synthesis, or hightemperature selective metal desorption under vacuum. Depending on the synthesis method, carbide precursor, and reaction parameters, multiple carbon allotropes can be achieved, including endohedral particles composed of predominantly amorphous carbon, carbon nanotubes, epitaxial graphene, nanocrystalline diamond, onion-like carbon, and graphitic ribbons, barrels, and horns. These structures exhibit high porosity and specific surface areas, with highly tunable pore diameters, making them promising materials for supercapacitor-based energy storage, water filtration and capacitive desalinization, catalyst support, and cytokine removal.[8]

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Lonsdaleite mond)

(hexagonal

dia-

Main article: Lonsdaleite Lonsdaleite is a hexagonal allotrope of the carbon al-

lotrope diamond, believed to form from graphite present in   meteorites   upon their impact to   Earth. The great 7 Carbon nanofoam heat and stress of the impact transforms the graphite into diamond, but retains graphite’s hexagonal  crystal Main article: Carbon nanofoam lattice. Hexagonal diamond has also been synthesized in the laboratory, by compressing and heating graphite Carbon nanofoam is the fifth known allotrope of carbon either in a static press or using explosives. It can also discovered in 1997 by Andrei V. Rode and co-workers at be produced by the thermal decomposition of a polymer, the  Australian National University  in   Canberra. It con- poly(hydridocarbyne), at atmospheric pressure, under insists of a low-density cluster-assembly of carbon atoms ert gas atmosphere (e.g. argon, nitrogen), starting at temperature 110 °C (230 °F).[9][10][11] strung together in a loose three-dimensional web. Each cluster is about 6 nanometers wide and consists of about 4000 carbon  atoms   linked in   graphite-like sheets that are given negative curvature by the inclu- 10 Linear acetylenic carbon (LAC) sion of heptagons among the regular hexagonal  pattern. This is the opposite of what happens in the case of Main article: Linear acetylenic carbon buckminsterfullerenes, in which carbon sheets are given positive curvature by the inclusion of pentagons. A one-dimensional carbon polymer with the structure The large-scale structure of carbon nanofoam is similar (C:::C) . to that of an aerogel, but with 1% of the density of previously produced carbon aerogels – only a few times the density of air at sea level. Unlike carbon aerogels, carbon 11 Other possible forms nanofoam is a poor electrical conductor. −

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in meteorite impacts. It has been described as slightly harder than graphite with a reflection colour of grey to white. However, the existence of carbyne phases is disputed – see the entry on  chaoite for details.

Carbide-derived carbon

Main article: Carbide-derived carbon Carbide-derived carbon (CDC) is a family of carbon materials with different surface geometries and carbon ordering that are produced via selective removal of metals from metal carbide precursors, such as TiC, SiC,

  Chaoite  is a mineral believed to have been formed

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  Metallic carbon : Theoretical studies have shown

that there are regions in the phase diagram, at extremely high pressures, where carbon has metallic character. [12]

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  There is an evidence that   white dwarf   stars have a core of crystallized carbon and oxygen nuclei. The largest of these found in the universe so far, BPM 37093, is located 50 light-years (4.7×1014 km) away in the constellation   Centaurus. A news release from the   Harvard-Smithsonian Center for Astrophysics described the 2,500-mile (4,000 km)wide stellar core as a  diamond ,[28] and it was named as   Lucy, after the Beatles’ song “Lucy in the Sky With Diamonds";[29] however, it is more likely an exotic form of carbon.   Prismane C8 is a theoretically-predicted metastable

carbon   allotrope   comprising an atomic   cluster of eight carbon atoms, with the shape of an  elongated triangular bipyramid—a six-atom triangular prism with two more atoms above and below its bases. [30]

Crystal structure of C 8  cubic carbon

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  bcc-carbon: At ultrahigh pressures of above 1000

GPa, diamond is predicted to transform into the socalled C8  structure, a body-centered cubic structure with 8 atoms in the unit cell. This  cubic carbon phase might have importance in astrophysics. Its structure is known in one of the metastable phases of silicon and is similar to cubane.[13] Superdense and superhard material resembling this phase has been synthesized and published in 1979   [14] and 2008.[15][16] The structure of this phase was proThe K 4  crystal  posed in 2012 as carbon sodalite. [17] •

  bct-carbon: Body-centered tetragonal carbon pro-

posed by theorists in 2010 •

[18][19]

  M-carbon: Monoclinic C-centered carbon was first

thought to have been created in 1963 by compressing graphite at room temperature. Its structure was theorized in 2006,[20] then in 2009 it was related[21] to those experimental observations. Many structural candidates, including bct-carbon, were proposed to be equally compatible with experimental data available at the time, until in 2012 it was theoretically proven that this structure is kinetically likeliest to form from graphite.[22][23] High-resolution data appeared shortly after, demonstrating that among all structure candidates only M-carbon is compatible with experiment.[24][25] •

  Q-carbon:   Ferromagnetic   carbon discovered in

2015.[26]

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The  Laves graph  or K 4  crystal  is a theoreticallypredicted three-dimensional crystalline metastable carbon structure in which each carbon atom is bonded to three others, at 120° angles (like graphite), but where the bond planes of adjacent lie at an angle of 70.5°, rather than coinciding[31][32]   Penta-graphene   Haeckelites   Ordered arrangements of pentagons, hexagons, and heptagons which can either be flat or tubular.   Phagraphene   Graphene allotrope with distorted

Dirac cones.

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Variability of carbon

The system of carbon allotropes spans an astounding range of extremes, considering that they are all merely   T-carbon: Every carbon atom in diamond is replaced with a carbon tetrahedron (hence 'T-carbon'). structural formations of the same element. This was proposed by theorists in 2011. [27] Between diamond and graphite:

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REFERENCES 

References

[1]  Glowing nuclear reactor graphite 2. YouTube (2007-1107). Retrieved on 2015-10-22. [2]  Crucibles, Artisan Foundry Shop. Artisanfoundry.co.uk. Retrieved on 2015-10-22. [3] Randall L. Vander Wal (1996).  “Soot Precursor Material: Spatial Location via Simultaneous LIF-LII Imaging and Characterization via TEM: NASA Contractor Report 198469”. [4]   “IUPAC Compendium of Chemical Terminology 2nd Edition (1997) diamond-like carbon films”. Diamond and graphite are two allotropes of carbon: pure forms  of the same element that differ in structure.

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  Diamond crystallizes in the   cubic system but graphite crystallizes in the hexagonal system.  Diamond is clear and transparent, but graphite is black and opaque.  Diamond is the hardest mineral known (10 on the Mohs scale), but graphite is one of the softest (1–2 on Mohs scale). Diamond is the ultimate abrasive, but graphite is soft and is a very good lubricant.   Diamond is an excellent electrical insulator, but graphite is a conductor of electricity.   Diamond is an excellent thermal conductor, but some forms of graphite are used for thermal insulation (for example heat shields and firebreaks).   At standard temperature and pressure, graphite is the thermodynamically stable form. Thus diamonds do not exist forever. 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 three-dimensional lattice. In graphite, the atoms are tightly bonded into sheets, but the sheets can slide easily over each other, making graphite soft.[33]

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See also Superdense carbon allotropes

[5] Reactions of Atomic Carbon with Acid Chlorides. None. Retrieved on 2011-11-23. [6] Martin Harwit (1998).  Astrophysical concepts . Springer. ISBN 978-0-387-94943-7. Retrieved 24 November 2011. [7]   Green Comet Approaches Earth. Science.nasa.gov (2009-02-24). Retrieved on 2011-11-23. [8] Presser, Volker; Heon, Min; Gogotsi, Yury (2011). “Carbide-Derived Carbons – From Porous Networks to Nanotubes and Graphene”.  Advanced Functional Materials .  21  (5): 810–833. doi:10.1002/adfm.201002094. [9] Bianconi P, et al. (2004). “Diamond and Diamondlike Carbon from a Preceramic Polymer”. Journal of  the American Chemical Society . 126   (10): 3191–3202. doi:10.1021/ja039254l. PMID 15012149. [10] Nur, Yusuf; Pitcher, Michael; Seyyidoğlu, Semih; Toppare, Levent (2008). “Facile Synthesis of Poly(hydridocarbyne): A Precursor to Diamond and Diamond-like Ceramics”.   Journal  of Macromolecular Science Part A . 45 (5): 358. doi:10.1080/10601320801946108. [11] Nur, Yusuf; Cengiz, Halime M.; Pitcher, Michael W.; Toppare, Levent K. (2009). “Electrochemical polymerizatıon of hexachloroethane to form poly(hydridocarbyne): a pre-ceramic polymer for diamond production”. Journal of Materials Science. 44 (11): 2774.   Bibcode:2009JMatS..44.2774N. doi:10.1007/s10853-009-3364-4. [12] Correa, Aa; Bonev, Sa; Galli, G (Jan 2006). “Carbon under extreme conditions: phase boundaries and electronic properties from first-principles theory”. Proceedings of the National Academy 103 of Sciences of the United States of America. (5): 1204–8.   Bibcode:2006PNAS..103.1204C. doi:10.1073/pnas.0510489103.   ISSN 0027-8424. PMC 1345714 . PMID 16432191. [13] Johnston, Roy L.; Hoffmann, Roald (1989). “Superdense carbon, C8: supercubane or analog of .gamma.-silicon?". Journal of the American Chemical Society . 111 (3): 810. doi:10.1021/ja00185a004. [14] Matyushenko N.N.; Strel'nitsky V.E. (1979). “JETP Letters: issues online”.  www.jetpletters.ac.ru . p. 199.

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[15] Liu, P.; Cui, H.; Yang, G. W. (2008). “Synthesis of BodyCentered Cubic Carbon Nanocrystals”. Crystal Growth & Design.  8  (2): 581. doi:10.1021/cg7006777.

[28] “This Valentine’s Day, Give The Woman Who Has Everything The Galaxy’s Largest Diamond”. Center for Astrophysics. Retrieved 2009-05-05.

[16] Liu, P; Cao, Yl; Wang, Cx; Chen, Xy; Yang, Gw (Aug 2008). “Micro- and nanocubes of carbon with C8-like and blue luminescence”.   Nano letters . 8   (8): 2570–5. Bibcode:2008NanoL...8.2570L. doi:10.1021/nl801392v. ISSN 1530-6984. PMID 18651780.

[29] Cauchi, S. (2004-02-18).  “Biggest Diamond Out of This World”. The Age.   Archived   from the original on 4 November 2007. Retrieved 2007-11-11.

[17] Pokropivny, Alex; Volz, Sebastian (2012-09-01).   "'C8 phase': Supercubane, tetrahedral, BC-8 or carbon sodalite?".   physica status solidi (b) . 249  (9): 1704–1708. doi:10.1002/pssb.201248185. ISSN 1521-3951. [18] Wolfram Demonstrations Project. Demonstrations.wolfram.com. Retrieved on 2011-11-23. [19] Edwards, Lin (November 8, 2010) Structure of new form of super-hard carbon identified. Physorg.com. Retrieved on 2011-11-23.

[30] Openov, Leonid A.; Elesin, Vladimir F. (1998). “Prismane C8 : A new form of carbon?".   JETP  68 (9): 726.   arXiv:physics/9811023 . Letters . Bibcode:1998JETPL..68..726O. doi:10.1134/1.567936. [31] Itoh, Masahiro; Kotani, Motoko; Naito, Hisashi; Sunada, Toshikazu; Kawazoe, Yoshiyuki; Adschiri, Tadafumi (2009), “New metallic carbon crystal”,   Physical Review Letters , 102 (5): 055703,   Bibcode:2009PhRvL.102e5703I, doi:10.1103/PhysRevLett.102.055703

[32] Tagami, Makoto; Liang, Yunye; Naito, Hisashi; Kawazoe, Yoshiyuki; Kotani, Motoko (2014), “Negatively curved cubic carbon crystals with octahedral symmetry”, Carbon, [20]   Oganov A. R.; Glass C. W. (2006). “Crystal 76: 266–274, doi:10.1016/j.carbon.2014.04.077 structure prediction using ab initio evolutionary techniques: principles and applications”. J. Chem. Phys . [33] Gray, Theodore (September 2009). “Gone in a Flash”. 124   (3): 244704.   Bibcode:2006JChPh.124c4704K. Popular Science: 70. doi:10.1063/1.2155529. [21] Li, Q.; Ma, Y.; Oganov, A.R.; Wang, H.B.; Wang, H.; Xu, Y.; Cui, T.; Mao, H.-K.; Zou, G. (2009). “Superhard monoclinic polymorph of carbon”.   Phys. Rev. Lett . 102 (17): 175506.   Bibcode:2009PhRvL.102q5506L. doi:10.1103/PhysRevLett.102.175506.   PMID 19518796. [22] Boulfelfel S.E.; Oganov A.R.; Leoni S. (2012). “Understanding the nature of “superhard graphite"". Scientific Reports . 2: 471.   arXiv:1204.4750 . Bibcode:2012NatSR...2E.471B. doi:10.1038/srep00471. PMC 3384968 . PMID 22745897. [23]   Oganov, Artem R. (27 June 2012).  “Researchers establish structure of a new superhard form of carbon”. Retrieved 23 July 2012. [24] Wang Y.; Panzik J.E.; Kiefer B.; Lee K.K.M. (2012). “Crystal structure of graphite under roomtemperature compression and decompression”.   Scientific Reports . 2: 520.   Bibcode:2012NatSR...2E.520W. doi:10.1038/srep00520. PMC 3400081 .   PMID 22816043. [25] Lee, Kanani K. M. (20 July 2012). “Diamond in the rough: Half-century puzzle solved”. Retrieved 23 July 2012. [26] Narayan, Jagdish; Bhaumik, Anagh (2 December 2015). “Novel phase of carbon, ferromagnetism, and conversion into diamond”.  Journal of Applied Physics . J. Appl. Phys. 118   (215303): 215303. doi:10.1063/1.4936595. Retrieved 2 December 2015. [27] Zyga, Lisa (April 22, 2011) New carbon allotrope could have a variety of applications. PhysOrg.com. Retrieved on 2012-08-09.

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External links Falcao, Eduardo H. L.; Wudl, Fred (2007). “Carbon allotropes: beyond graphite and diamond”.   Journal of Chemical Technology & Biotechnology . 82 (6): 524–531. doi:10.1002/jctb.1693. ISSN 02682575.  http://www.dendritics.com/scales/c-allotropes.asp  http://cst-www.nrl.navy.mil/lattice/struk/carbon. html  diamond 3D animation

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Text and image sources, contributors, and licenses

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TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES 

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Allotropes of carbon   Source:  https://en.wikipedia.org/wiki/Allotropes_of_carbon?oldid=737212854   Contributors:    Bryan Derksen,

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