Allotropes of carbon
Allotropes of Carbon
- Atomic carbon can be formed by vaporizing graphite or by passing large electric currents to form a carbon arc under very low pressure. It is extremely reactive and used in the creation of carbenes.
- Diatomic carbon can also be found under certain conditions and is often detected in extraterrestrial bodies. Spectroscopy is used to detect diatomic carbon in comets and certain stars.
- Diamond is the hardest known natural mineral and has a high refractive index and dispersion of light. It is used for industrial applications and jewelry due to its hardness and luster. Diamond has a face-centered cubic lattice structure with each carbon atom covalently bonded to four other carbons. It is thermodynamically less stable than graphite at pressures below 1.7GPa.
- Graphite is an electrical conductor and the most stable form of carbon under standard conditions. It conducts electricity along the planes of carbon atoms but not in a direction at right angles to the plane. Graphite powder is used as a dry lubricant. When crystallographic defects bind the planes together, graphite becomes pyrolytic carbon. Graphite is used in nuclear reactors, high-temperature crucibles, and as a structural material in glassy synthetic forms.
- Graphene is a single layer of graphite with extraordinary electrical, thermal, and physical properties. It can be produced by epitaxy or mechanical exfoliation from graphite. Graphene has the potential to replace silicon in high-performance electronic devices. It has high conductivity and is transparent, flexible, and strong. Graphene has applications in areas such as energy storage, sensors, and nanoelectronics.
Industrial Uses of Diamonds
- Industrial diamonds are valued for their hardness and heat conductivity. Around 80% of mined diamonds are unsuitable for use as gemstones and are used for industrial purposes. Synthetic diamonds are also used for industrial applications and are produced at a larger scale than natural diamonds. Research is being conducted to explore the potential use of diamond as a semiconductor and heat sink in electronics.
Other Allotropes of Carbon
- Lonsdaleite is an allotrope formed from graphite in meteorites upon impact on Earth. It retains graphite's hexagonal crystal lattice and can be synthesized in the laboratory.
- Graphenylene is a single layer carbon material with a hexagonal lattice structure.
- Carbophene is a 2-dimensional covalent organic framework synthesized from 1-3-5 trihydroxybenzene.
- AA-graphite is an allotrope of carbon similar to graphite but with a different order of layers in its structure.
- Diamane is a 2D form of diamond that can be made via high pressures. Adding hydrogen atoms weakens the bonds, while using fluorine brings the layers closer together, creating f-diamane.
- Amorphous carbon does not have a crystalline structure and can contain microscopic crystals of graphite-like or diamond-like carbon.
- Buckminsterfullerenes, also known as fullerenes or buckyballs, are positively curved molecules composed entirely of carbon. They can take the form of a hollow sphere, ellipsoid, or tube. Fullerenes have various chemical and physical properties that are still under study.
- Carbon nanotubes are cylindrical carbon molecules with extraordinary strength and unique electrical properties. There are two main types: single-walled and multi-walled. Carbon nanobuds are a hybrid material of fullerenes and carbon nanotubes.
- Schwarzites are negatively curved carbon surfaces that can be formed by decorating triply periodic minimal surfaces with carbon atoms. Recent work has suggested that zeolite-templated carbons may be schwarzites.
- Glassy carbon is a non-graphitizing carbon widely used in electrochemistry. It is impermeable to gases and chemically inert.
- Carbon nanofoam is a low-density cluster-assembly of carbon atoms in a three-dimensional web. It includes heptagons and has potential applications in energy storage.
Carbide-derived Carbon and Other Carbon Polymers
- Carbide-derived carbon is produced via selective removal of metals from metal carbide precursors. Multiple carbon allotropes can be achieved, including amorphous carbon, carbon nanotubes, epitaxial graphene, nanocrystalline diamond, and onion-like carbon. These structures have high porosity and specific surface areas, making them suitable for various applications.
- Linear acetylenic carbon is a one-dimensional carbon polymer with a structure similar to amorphous carbon. It contains carbon-carbon triple bonds.
- Cyclocarbon is a synthesized carbon allotrope with a structure consisting of 18 carbon atoms arranged in a cyclic pattern.
Hypothesized Allotropes of Carbon
- Various hypothesized allotropes of carbon have yet to be synthesized, including bcc-carbon, cubane-like structure, carbon sodalite, body-centered tetragonal carbon, chaoite, D-carbon, haeckelites, Laves graph, monoclinic C-centered carbon, metallic carbon, novamene, phagraphene, prismane C, protomene, Q-carbon, T-carbon, penta-graphene, U carbon, and Zayedene.
Variability of Carbon
- Diamond and graphite are two pure forms of carbon with different structures. Diamond crystallizes in the cubic system, while graphite crystallizes in the hexagonal system. Diamond is clear and transparent, while graphite is opaque.
Allotropes of carbon Data Sources