1.
Fullerene
–
A fullerene is a molecule of carbon in the form of a hollow sphere, ellipsoid, tube, and many other shapes. Spherical fullerenes, also referred to as Buckminsterfullerenes, resemble the balls used in football, cylindrical fullerenes are also called carbon nanotubes. Fullerenes are similar in structure to graphite, which is composed of stacked sheets of linked hexagonal rings. The name was an homage to Buckminster Fuller, whose geodesic domes it resembles, the structure was also identified some five years earlier by Sumio Iijima, from an electron microscope image, where it formed the core of a bucky onion. Fullerenes have since found to occur in nature. More recently, fullerenes have been detected in outer space, according to astronomer Letizia Stanghellini, It’s possible that buckyballs from outer space provided seeds for life on Earth. The discovery of fullerenes greatly expanded the number of carbon allotropes, which until recently were limited to graphite, graphene, diamond. The icosahedral C60H60 cage was mentioned in 1965 as a topological structure. Eiji Osawa of Toyohashi University of Technology predicted the existence of C60 in 1970 and he noticed that the structure of a corannulene molecule was a subset of an Association football shape, and he hypothesised that a full ball shape could also exist. Japanese scientific journals reported his idea, but neither it nor any translations of it reached Europe or the Americas, also in 1970, R. W. Henson proposed the structure and made a model of C60. Unfortunately, the evidence for new form of carbon was very weak and was not accepted. The results were never published but were acknowledged in Carbon in 1999, in 1973 independently from Henson, a group of scientists from the USSR, directed by Prof. Bochvar, made a quantum-chemical analysis of the stability of C60 and calculated its electronic structure. As in the cases, the scientific community did not accept the theoretical prediction. The paper was published in 1973 in Proceedings of the USSR Academy of Sciences, in mass spectrometry discrete peaks appeared corresponding to molecules with the exact mass of sixty or seventy or more carbon atoms. Kroto, Curl, and Smalley were awarded the 1996 Nobel Prize in Chemistry for their roles in the discovery of this class of molecules, C60 and other fullerenes were later noticed occurring outside the laboratory. By 1990 it was easy to produce gram-sized samples of fullerene powder using the techniques of Donald Huffman, Wolfgang Krätschmer, Lowell D. Lamb. Fullerene purification remains a challenge to chemists and to a large extent determines fullerene prices, so-called endohedral fullerenes have ions or small molecules incorporated inside the cage atoms. Fullerene is a reactant in many organic reactions such as the Bingel reaction discovered in 1993
2.
Carbon
–
Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
3.
Hexagon
–
In geometry, a hexagon is a six sided polygon or 6-gon. The total of the angles of any hexagon is 720°. A regular hexagon has Schläfli symbol and can also be constructed as an equilateral triangle, t. A regular hexagon is defined as a hexagon that is both equilateral and equiangular and it is bicentric, meaning that it is both cyclic and tangential. The common length of the sides equals the radius of the circumscribed circle, all internal angles are 120 degrees. A regular hexagon has 6 rotational symmetries and 6 reflection symmetries, the longest diagonals of a regular hexagon, connecting diametrically opposite vertices, are twice the length of one side. Like squares and equilateral triangles, regular hexagons fit together without any gaps to tile the plane, the cells of a beehive honeycomb are hexagonal for this reason and because the shape makes efficient use of space and building materials. The Voronoi diagram of a triangular lattice is the honeycomb tessellation of hexagons. It is not usually considered a triambus, although it is equilateral, the maximal diameter, D is twice the maximal radius or circumradius, R, which equals the side length, t. The minimal diameter or the diameter of the circle, d, is twice the minimal radius or inradius. If a regular hexagon has successive vertices A, B, C, D, E, F, the regular hexagon has Dih6 symmetry, order 12. There are 3 dihedral subgroups, Dih3, Dih2, and Dih1, and 4 cyclic subgroups, Z6, Z3, Z2 and these symmetries express 9 distinct symmetries of a regular hexagon. John Conway labels these by a letter and group order, r12 is full symmetry, and a1 is no symmetry. These two forms are duals of each other and have half the order of the regular hexagon. The i4 forms are regular hexagons flattened or stretched along one symmetry direction and it can be seen as an elongated rhombus, while d2 and p2 can be seen as horizontally and vertically elongated kites. G2 hexagons, with sides parallel are also called hexagonal parallelogons. Each subgroup symmetry allows one or more degrees of freedom for irregular forms, only the g6 subgroup has no degrees of freedom but can seen as directed edges. Hexagons of symmetry g2, i4, and r12, as parallelogons can tessellate the Euclidean plane by translation, other hexagon shapes can tile the plane with different orientations
4.
Pentagon
–
In geometry, a pentagon is any five-sided polygon or 5-gon. The sum of the angles in a simple pentagon is 540°. A pentagon may be simple or self-intersecting, a self-intersecting regular pentagon is called a pentagram. A regular pentagon has Schläfli symbol and interior angles are 108°, a regular pentagon has five lines of reflectional symmetry, and rotational symmetry of order 5. The diagonals of a regular pentagon are in the golden ratio to its sides. The area of a regular convex pentagon with side length t is given by A = t 225 +1054 =5 t 2 tan 4 ≈1.720 t 2. A pentagram or pentangle is a regular star pentagon and its sides form the diagonals of a regular convex pentagon – in this arrangement the sides of the two pentagons are in the golden ratio. The area of any polygon is, A =12 P r where P is the perimeter of the polygon. Substituting the regular pentagons values for P and r gives the formula A =12 ×5 t × t tan 2 =5 t 2 tan 4 with side length t, like every regular convex polygon, the regular convex pentagon has an inscribed circle. The apothem, which is the r of the inscribed circle. Like every regular polygon, the regular convex pentagon has a circumscribed circle. For a regular pentagon with successive vertices A, B, C, D, E, the regular pentagon is constructible with compass and straightedge, as 5 is a Fermat prime. A variety of methods are known for constructing a regular pentagon, one method to construct a regular pentagon in a given circle is described by Richmond and further discussed in Cromwells Polyhedra. The top panel shows the construction used in Richmonds method to create the side of the inscribed pentagon, the circle defining the pentagon has unit radius. Its center is located at point C and a midpoint M is marked halfway along its radius and this point is joined to the periphery vertically above the center at point D. Angle CMD is bisected, and the bisector intersects the axis at point Q. A horizontal line through Q intersects the circle at point P, to determine the length of this side, the two right triangles DCM and QCM are depicted below the circle. Using Pythagoras theorem and two sides, the hypotenuse of the triangle is found as 5 /2
5.
Polygon
–
In elementary geometry, a polygon /ˈpɒlɪɡɒn/ is a plane figure that is bounded by a finite chain of straight line segments closing in a loop to form a closed polygonal chain or circuit. These segments are called its edges or sides, and the points where two edges meet are the vertices or corners. The interior of the polygon is called its body. An n-gon is a polygon with n sides, for example, a polygon is a 2-dimensional example of the more general polytope in any number of dimensions. The basic geometrical notion of a polygon has been adapted in various ways to suit particular purposes, mathematicians are often concerned only with the bounding closed polygonal chain and with simple polygons which do not self-intersect, and they often define a polygon accordingly. A polygonal boundary may be allowed to intersect itself, creating star polygons and these and other generalizations of polygons are described below. The word polygon derives from the Greek adjective πολύς much, many and it has been suggested that γόνυ knee may be the origin of “gon”. Polygons are primarily classified by the number of sides, Polygons may be characterized by their convexity or type of non-convexity, Convex, any line drawn through the polygon meets its boundary exactly twice. As a consequence, all its interior angles are less than 180°, equivalently, any line segment with endpoints on the boundary passes through only interior points between its endpoints. Non-convex, a line may be found which meets its boundary more than twice, equivalently, there exists a line segment between two boundary points that passes outside the polygon. Simple, the boundary of the polygon does not cross itself, there is at least one interior angle greater than 180°. Star-shaped, the interior is visible from at least one point. The polygon must be simple, and may be convex or concave, self-intersecting, the boundary of the polygon crosses itself. Branko Grünbaum calls these coptic, though this term does not seem to be widely used, star polygon, a polygon which self-intersects in a regular way. A polygon cannot be both a star and star-shaped, equiangular, all corner angles are equal. Cyclic, all lie on a single circle, called the circumcircle. Isogonal or vertex-transitive, all lie within the same symmetry orbit. The polygon is cyclic and equiangular
6.
Chromatography
–
Chromatography is a laboratory technique for the separation of a mixture. The mixture is dissolved in a called the mobile phase. The various constituents of the mixture travel at different speeds, causing them to separate, the separation is based on differential partitioning between the mobile and stationary phases. Subtle differences in a partition coefficient result in differential retention on the stationary phase. Chromatography may be preparative or analytical, the purpose of preparative chromatography is to separate the components of a mixture for later use, and is thus a form of purification. Analytical chromatography is done normally with smaller amounts of material and is for establishing the presence or measuring the proportions of analytes in a mixture. The two are not mutually exclusive, Chromatography was first employed in Russia by the Italian-born scientist Mikhail Tsvet in 1900. He continued to work with chromatography in the first decade of the 20th century, primarily for the separation of plant pigments such as chlorophyll, carotenes, since these components have different colors they gave the technique its name. New types of chromatography developed during the 1930s and 1940s made the technique useful for separation processes. Since then, the technology has advanced rapidly, researchers found that the main principles of Tsvets chromatography could be applied in many different ways, resulting in the different varieties of chromatography described below. Advances are continually improving the performance of chromatography, allowing the separation of increasingly similar molecules. The analyte is the substance to be separated during chromatography and it is also normally what is needed from the mixture. Analytical chromatography is used to determine the existence and possibly also the concentration of analyte in a sample, a bonded phase is a stationary phase that is covalently bonded to the support particles or to the inside wall of the column tubing. A chromatogram is the output of the chromatograph. In the case of a separation, different peaks or patterns on the chromatogram correspond to different components of the separated mixture. Plotted on the x-axis is the time and plotted on the y-axis a signal corresponding to the response created by the analytes exiting the system. In the case of a system the signal is proportional to the concentration of the specific analyte separated. A chromatograph is equipment that enables a sophisticated separation, e. g. gas chromatographic or liquid chromatographic separation, Chromatography is a physical method of separation that distributes components to separate between two phases, one stationary, the other moving in a definite direction
7.
Laser ablation
–
Laser ablation is the process of removing material from a solid surface by irradiating it with a laser beam. At low laser flux, the material is heated by the laser energy. At high laser flux, the material is converted to a plasma. Usually, laser ablation refers to removing material with a pulsed laser, the total mass ablated from the target per laser pulse is usually referred to as ablation rate. Such features of laser radiation as laser beam scanning velocity and the covering of scanning lines can significantly influence the ablation process, laser pulses can vary over a very wide range of duration and fluxes, and can be precisely controlled. This makes laser ablation very valuable for both research and industrial applications, the simplest application of laser ablation is to remove material from a solid surface in a controlled fashion. Laser machining and particularly laser drilling are examples, pulsed lasers can drill extremely small, several workers have employed laser ablation and gas condensation to produce nano particles of metal, metal oxides and metal carbides. High power lasers clean a large spot with a single pulse, lower power lasers use many small pulses which may be scanned across an area. One of the advantages is that no solvents are used, therefore it is environmentally friendly and it is relatively easy to automate. The running costs are lower than dry media or dry-ice blasting, the process is gentler than abrasive techniques, e. g. carbon fibres within a composite material are not damaged. Heating of the target is minimal, another class of applications uses laser ablation to process the material removed into new forms either not possible or difficult to produce by other means. A recent example is the production of carbon nanotubes, in March 1995 Guo et al. were the first to report the use of a laser to ablate a block of pure graphite, and later graphite mixed with catalytic metal. The catalytic metal can consist of such as cobalt, niobium, platinum, nickel, copper. The composite block is formed by making a paste of graphite powder, carbon cement, the paste is next placed in a cylindrical mold and baked for several hours. After solidification, the block is placed inside an oven with a laser pointed at it. The oven temperature is approximately 1200 °C, as the laser ablates the target, carbon nanotubes form and are carried by the gas flow onto a cool copper collector. Like carbon nanotubes formed using the electric-arc discharge technique, carbon fibers are deposited in a haphazard. Single-walled nanotubes are formed from the block of graphite and metal catalyst particles and this process is used to manufacture some types of high temperature superconductor and laser crystals
8.
Pyrolysis
–
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen. It involves the change of chemical composition and physical phase. The word is coined from the Greek-derived elements pyro fire and lysis separating, Pyrolysis is a type of thermolysis, and is most commonly observed in organic materials exposed to high temperatures. It is one of the involved in charring wood, starting at 200–300 °C. It also occurs in fires where solid fuels are burning or when vegetation comes into contact with lava in volcanic eruptions, in general, pyrolysis of organic substances produces gas and liquid products and leaves a solid residue richer in carbon content, char. Extreme pyrolysis, which leaves mostly carbon as the residue, is called carbonization and these specialized uses of pyrolysis may be called various names, such as dry distillation, destructive distillation, or cracking. Pyrolysis is also used in the creation of nanoparticles, zirconia, Pyrolysis also plays an important role in several cooking procedures, such as baking, frying, grilling, and caramelizing. It is a tool of analysis, for example, in mass spectrometry. Indeed, many important chemical substances, such as phosphorus and sulfuric acid, were first obtained by this process, Pyrolysis has been assumed to take place during catagenesis, the conversion of buried organic matter to fossil fuels. It is also the basis of pyrography, in their embalming process, the ancient Egyptians used a mixture of substances, including methanol, which they obtained from the pyrolysis of wood. Pyrolysis differs from other processes like combustion and hydrolysis in that it usually does not involve reactions with oxygen, water, in practice, it is not possible to achieve a completely oxygen-free atmosphere. Because some oxygen is present in any system, a small amount of oxidation occurs. The term has also applied to the decomposition of organic material in the presence of superheated water or steam, for example. Pyrolysis is usually the first chemical reaction occurs in the burning of many solid organic fuels, like wood, cloth, and paper. Thus, the pyrolysis of common materials like wood, plastic, in pyrolysis there is a gas phase present. Pyrolysis occurs whenever food is exposed to high temperatures in a dry environment, such as roasting, baking, toasting. It is the process responsible for the formation of the golden-brown crust in foods prepared by those methods. In normal cooking, the food components that undergo pyrolysis are carbohydrates
9.
Aromatic hydrocarbon
–
An aromatic hydrocarbon or arene is a hydrocarbon with sigma bonds and delocalized pi electrons between carbon atoms forming a circle. In contrast, aliphatic hydrocarbons lack this delocalization, the term aromatic was assigned before the physical mechanism determining aromaticity was discovered, the term was coined as such simply because many of the compounds have a sweet or pleasant odour. The configuration of six carbon atoms in compounds is known as a benzene ring, after the simplest possible such hydrocarbon. Aromatic hydrocarbons can be monocyclic or polycyclic, some non-benzene-based compounds called heteroarenes, which follow Hückels rule, are also called aromatic compounds. In these compounds, at least one atom is replaced by one of the heteroatoms oxygen, nitrogen. Benzene, C6H6, is the simplest aromatic hydrocarbon, and it was the first one named as such, the nature of its bonding was first recognized by August Kekulé in the 19th century. Each carbon atom in the cycle has four electrons to share. One goes to the atom, and one each to the two neighbouring carbons. The structure is alternatively illustrated as a circle around the inside of the ring to show six electrons floating around in delocalized molecular orbitals the size of the ring itself. This depiction represents the equivalent nature of the six carbon–carbon bonds all of bond order 1.5, the electrons are visualized as floating above and below the ring with the electromagnetic fields they generate acting to keep the ring flat. The proper use of the symbol is debated, it is used to describe any cyclic π system in some publications, jensen argues that, in line with Robinsons original proposal, the use of the circle symbol should be limited to monocyclic 6 π-electron systems. In this way the symbol for a six-center six-electron bond can be compared to the Y symbol for a three-center two-electron bond. A reaction that forms a compound from an unsaturated or partially unsaturated cyclic precursor is simply called an aromatization. Many laboratory methods exist for the synthesis of arenes from non-arene precursors. Many methods rely on cycloaddition reactions, alkyne trimerization describes the cyclization of three alkynes, in the Dötz reaction an alkyne, carbon monoxide and a chromium carbene complex are the reactants. Diels–Alder reactions of alkynes with pyrone or cyclopentadienone with expulsion of carbon dioxide or carbon monoxide also form arene compounds, in Bergman cyclization the reactants are an enyne plus a hydrogen donor. Arenes are reactants in many organic reactions, in aromatic substitution one substituent on the arene ring, usually hydrogen, is replaced by another substituent. The two main types are electrophilic aromatic substitution when the reagent is an electrophile and nucleophilic aromatic substitution when the reagent is a nucleophile
10.
Molecular symmetry
–
Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of molecules according to their symmetry. Molecular symmetry is a concept in chemistry, as it can predict or explain many of a molecules chemical properties, such as its dipole moment. Many university level textbooks on chemistry, quantum chemistry. While various frameworks for the study of symmetry exist, group theory is the predominant one. This framework is useful in studying the symmetry of molecular orbitals, with applications such as the Hückel method, ligand field theory. Another framework on a scale is the use of crystal systems to describe crystallographic symmetry in bulk materials. Many techniques for the assessment of molecular symmetry exist, including X-ray crystallography and various forms of spectroscopy. Spectroscopic notation is based on symmetry considerations, the study of symmetry in molecules is an adaptation of mathematical group theory. The symmetry of a molecule can be described by 5 types of symmetry elements, symmetry axis, an axis around which a rotation by 360 ∘ n results in a molecule indistinguishable from the original. This is also called a rotational axis and abbreviated Cn. Examples are the C2 axis in water and the C3 axis in ammonia, a molecule can have more than one symmetry axis, the one with the highest n is called the principal axis, and by convention is aligned with the z-axis in a Cartesian coordinate system. Plane of symmetry, a plane of reflection through which a copy of the original molecule is generated. This is also called a plane and abbreviated σ. Water has two of them, one in the plane of the molecule itself and one perpendicular to it, a symmetry plane parallel with the principal axis is dubbed vertical and one perpendicular to it horizontal. A third type of symmetry plane exists, If a vertical symmetry plane additionally bisects the angle between two 2-fold rotation axes perpendicular to the axis, the plane is dubbed dihedral. A symmetry plane can also be identified by its Cartesian orientation, center of symmetry or inversion center, abbreviated i. A molecule has a center of symmetry when, for any atom in the molecule, in other words, a molecule has a center of symmetry when the points and correspond to identical objects. For example, if there is an atom in some point
11.
Isomer
–
An isomer is a molecule with the same molecular formula as another molecule, but with a different chemical structure. That is, isomers contain the number of atoms of each element. Isomers do not necessarily share similar properties, unless they also have the functional groups. There are two forms of isomerism, structural isomerism and stereoisomerism. In structural isomers, sometimes referred to as constitutional isomers, the atoms, Structural isomers have different IUPAC names and may or may not belong to the same functional group. For example, two position isomers would be 2-fluoropropane and 1-fluoropropane, illustrated on the side of the diagram above. In skeletal isomers the main chain is different between the two isomers. This type of isomerism is most identifiable in secondary and tertiary alcohol isomers, tautomers are structural isomers that spontaneously interconvert with each other, even when pure. They have different chemical properties and, as a consequence, distinct reactions characteristic to each form are observed, if the interconversion reaction is fast enough, tautomers cannot be isolated from each other. An example is when they differ by the position of a proton, such as in keto/enol tautomerism, there is, however, another isomer of C3H8O that has significantly different properties, methoxyethane. Unlike the isomers of propanol, methoxyethane has an oxygen connected to two carbons rather than to one carbon and one hydrogen. Methoxyethane is an ether, not an alcohol, because it lacks a hydroxyl group, propadiene and propyne are examples of isomers containing different bond types. Propadiene contains two double bonds, whereas propyne contains one triple bond, in stereoisomers the bond structure is the same, but the geometrical positioning of atoms and functional groups in space differs. This class includes enantiomers which are non-superposable mirror-images of each other, and diastereomers, enantiomers always contain chiral centers and diastereomers often do, but there are some diastereomers that neither are chiral nor contain chiral centers. Another type of isomer, conformational isomers, may be rotamers, diastereomers, for example, ortho- position-locked biphenyl systems have enantiomers. E/Z isomers, which have restricted rotation at a bond, are configurational isomers. They are classified as diastereomers, whether or not they contain any chiral centers, e/Z notation depicts absolute stereochemistry, which is an unambiguous descriptor based on CIP priorities. Cis–trans isomers are used to describe any molecules with restricted rotation in the molecule, for molecules with C=C double bonds, these descriptors describe relative stereochemistry only based on group bulkiness or principal carbon chain, and so can be ambiguous
12.
Space group
–
In mathematics, physics and chemistry, a space group is the symmetry group of a configuration in space, usually in three dimensions. In three dimensions, there are 219 distinct types, or 230 if chiral copies are considered distinct, Space groups are also studied in dimensions other than 3 where they are sometimes called Bieberbach groups, and are discrete cocompact groups of isometries of an oriented Euclidean space. In crystallography, space groups are called the crystallographic or Fedorov groups. A definitive source regarding 3-dimensional space groups is the International Tables for Crystallography, in 1879 Leonhard Sohncke listed the 65 space groups whose elements preserve the orientation. More accurately, he listed 66 groups, but Fedorov and Schönflies both noticed that two of them were really the same, the space groups in 3 dimensions were first enumerated by Fedorov, and shortly afterwards were independently enumerated by Schönflies. The correct list of 230 space groups was found by 1892 during correspondence between Fedorov and Schönflies, burckhardt describes the history of the discovery of the space groups in detail. The space groups in three dimensions are made from combinations of the 32 crystallographic point groups with the 14 Bravais lattices, the combination of all these symmetry operations results in a total of 230 different space groups describing all possible crystal symmetries. The elements of the space group fixing a point of space are rotations, reflections, the identity element, the translations form a normal abelian subgroup of rank 3, called the Bravais lattice. There are 14 possible types of Bravais lattice, the quotient of the space group by the Bravais lattice is a finite group which is one of the 32 possible point groups. Translation is defined as the moves from one point to another point. A glide plane is a reflection in a plane, followed by a parallel with that plane. This is noted by a, b or c, depending on which axis the glide is along. There is also the n glide, which is a glide along the half of a diagonal of a face, and the d glide, the latter is called the diamond glide plane as it features in the diamond structure. In 17 space groups, due to the centering of the cell, the glides occur in two directions simultaneously, i. e. the same glide plane can be called b or c, a or b. For example, group Abm2 could be also called Acm2, group Ccca could be called Cccb, in 1992, it was suggested to use symbol e for such planes. The symbols for five groups have been modified, A screw axis is a rotation about an axis. These are noted by a number, n, to describe the degree of rotation, the degree of translation is then added as a subscript showing how far along the axis the translation is, as a portion of the parallel lattice vector. So,21 is a rotation followed by a translation of 1/2 of the lattice vector
13.
Monoclinic crystal system
–
In crystallography, the monoclinic crystal system is one of the 7 crystal systems. A crystal system is described by three vectors, in the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a rectangular prism with a parallelogram as its base, hence two vectors are perpendicular, while the third vector meets the other two at an angle other than 90°. There is only one monoclinic Bravais lattice in two dimensions, the oblique lattice, two monoclinic Bravais lattices exist, the primitive monoclinic and the centered monoclinic lattices. In this axis setting, the primitive and base-centered lattices interchange in centering type, sphenoidal is also monoclinic hemimorphic, Domatic is also monoclinic hemihedral, Prismatic is also monoclinic normal. Crystal structure Hurlbut, Cornelius S. Klein, Cornelis, hahn, Theo, ed. International Tables for Crystallography, Volume A, Space Group Symmetry
14.
Cubic crystal system
–
In crystallography, the cubic crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals, there are three main varieties of these crystals, Primitive cubic Body-centered cubic, Face-centered cubic Each is subdivided into other variants listed below. Note that although the cell in these crystals is conventionally taken to be a cube. This is related to the fact that in most cubic crystal systems, a classic isometric crystal has square or pentagonal faces. The three Bravais lattices in the crystal system are, The primitive cubic system consists of one lattice point on each corner of the cube. Each atom at a point is then shared equally between eight adjacent cubes, and the unit cell therefore contains in total one atom. The body-centered cubic system has one point in the center of the unit cell in addition to the eight corner points. It has a net total of 2 lattice points per unit cell, Each sphere in a cF lattice has coordination number 12. The face-centered cubic system is related to the hexagonal close packed system. The plane of a cubic system is a hexagonal grid. Attempting to create a C-centered cubic crystal system would result in a simple tetragonal Bravais lattice, there are a total 36 cubic space groups. Other terms for hexoctahedral are, normal class, holohedral, ditesseral central class, a simple cubic unit cell has a single cubic void in the center. Additionally, there are 24 tetrahedral voids located in a square spacing around each octahedral void and these tetrahedral voids are not local maxima and are not technically voids, but they do occasionally appear in multi-atom unit cells. A face-centered cubic unit cell has eight tetrahedral voids located midway between each corner and the center of the cell, for a total of eight net tetrahedral voids. One important characteristic of a structure is its atomic packing factor. This is calculated by assuming all the atoms are identical spheres. The atomic packing factor is the proportion of space filled by these spheres, assuming one atom per lattice point, in a primitive cubic lattice with cube side length a, the sphere radius would be a⁄2 and the atomic packing factor turns out to be about 0.524. Similarly, in a bcc lattice, the atomic packing factor is 0.680, as a rule, since atoms in a solid attract each other, the more tightly packed arrangements of atoms tend to be more common
15.
Buckminsterfullerene
–
Buckminsterfullerene is a spherical fullerene molecule with the formula C60. It was first generated in 1985 by Harold Kroto, James R. Heath, Sean OBrien, Robert Curl, Kroto, Curl and Smalley were awarded the 1996 Nobel Prize in Chemistry for their roles in the discovery of buckminsterfullerene and the related class of molecules, the fullerenes. The name is a reference to Buckminster Fuller, as C60 resembles his trademark geodesic domes, Buckminsterfullerene is the most common naturally occurring fullerene molecule, as it can be found in small quantities in soot. Solid and gaseous forms of the molecule have been detected in deep space, Buckminsterfullerene is one of the largest objects to have been shown to exhibit wave–particle duality, as stated in the theory every object exhibits this behavior. Its discovery led to the exploration of a new field of chemistry, Buckminsterfullerene derives from the name of the noted futurist and inventor Buckminster Fuller. One of his designs of a dome structure bears great resemblance to C60, as a result. The general public, however, sometimes refers to buckminsterfullerene, and even Fullers dome structure, the structure associated with fullerenes was described by Leonardo da Vinci. Albrecht Dürer also reproduced a similar icosahedron containing 12 pentagonal and 20 hexagonal faces, theoretical predictions of buckyball molecules appeared in the late 1960s – early 1970s, but they went largely unnoticed. In the early 1970s, the chemistry of unsaturated carbon configurations was studied by a group at the University of Sussex, led by Harry Kroto, in the 1980s a technique was developed by Richard Smalley and Robert Curl at Rice University, Texas to isolate these substances. They used laser vaporization of a target to produce clusters of atoms. Kroto realized that by using a target, any carbon chains formed could be studied. Another interesting fact is that, at the time, astrophysicists were working along with spectroscopists to study infrared emissions from giant red carbon stars. Smalley and team were able to use a laser vaporization technique to create carbon clusters which could potentially emit infrared at the wavelength as had been emitted by the red carbon star. Hence, the inspiration came to Smalley and team to use the technique on graphite to create the first fullerene molecule. C60 was discovered in 1985 by Robert Curl, Harold Kroto, using laser evaporation of graphite they found Cn clusters of which the most common were C60 and C70. A solid rotating graphite disk was used as the surface from which carbon was vaporized using a laser beam creating hot plasma that was passed through a stream of high-density helium gas. The carbon species were subsequently cooled and ionized resulting in the formation of clusters, clusters ranged in molecular masses but Kroto and Smalley found predominance in a C60 cluster that could be enhanced further by letting the plasma react longer. They also discovered that the C60 molecule formed a cage-like structure, for this discovery they were awarded the 1996 Nobel Prize in Chemistry
16.
C70 fullerene
–
C70 fullerene is the fullerene molecule consisting of 70 carbon atoms. It is a cage-like fused-ring structure which resembles a ball, made of 25 hexagons and 12 pentagons, with a carbon atom at the vertices of each polygon. A related fullerene molecule, named buckminsterfullerene, consists of 60 carbon atoms and it was first intentionally prepared in 1985 by Harold Kroto, James R. Heath, Sean OBrien, Robert Curl and Richard Smalley at Rice University. Kroto, Curl and Smalley were awarded the 1996 Nobel Prize in Chemistry for their roles in the discovery of cage-like fullerenes, the name is a homage to Buckminster Fuller, whose geodesic domes these molecules resemble. Theoretical predictions of buckyball molecules appeared in the late 1960s – early 1970s, in the early 1970s, the chemistry of unsaturated carbon configurations was studied by a group at the University of Sussex, led by Harry Kroto and David Walton. In the 1980s a technique was developed by Richard Smalley and Bob Curl at Rice University and they used laser vaporization of a suitable target to produce clusters of atoms. Kroto realized that by using a graphite target, C70 was discovered in 1985 by Robert Curl, Harold Kroto and Richard Smalley. Using laser evaporation of graphite they found Cn clusters of which the most common were C60, for this discovery they were awarded the 1996 Nobel Prize in Chemistry. The discovery of buckyballs was serendipitous, as the scientists were aiming to produce carbon plasmas to replicate, mass spectrometry analysis of the product indicated the formation of spheroidal carbon molecules. In 1990, K. Fostiropoulos, W. Krätchmer and D. R. Huffman developed a simple and efficient method of producing fullerenes in gram and even kilogram amounts which boosted fullerene research. In this technique, carbon soot is produced from two high-purity graphite electrodes by igniting an arc discharge between them in an inert atmosphere, alternatively, soot is produced by laser ablation of graphite or pyrolysis of aromatic hydrocarbons. Fullerenes are extracted from the using a multistep procedure. First, the soot is dissolved in organic solvents. This step yields a solution containing up to 70% of C60 and 15% of C70 and these fractions are separated using chromatography. The C70 molecule has a D5h symmetry and contains 37 faces with an atom at the vertices of each polygon. Its structure is similar to that of C60 molecule, but has a belt of 5 hexagons inserted at the equator, the molecule has eight bond lengths ranging between 0.137 and 0.146 nm. Each carbon atom in the structure is bonded covalently with 3 others, C70 can undergo six reversible, one-electron reductions to C6−70, whereas oxidation is irreversible. The first reduction requires ~1.0 V, indicating that C70 is an electron acceptor, Fullerenes are sparingly soluble in many aromatic solvents such as toluene and others like carbon disulfide, but not in water
17.
International Standard Book Number
–
The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
18.
Allotropes of carbon
–
Carbon is capable of forming many allotropes due to its valency. Well-known forms of carbon include diamond and graphite, in recent decades many more allotropes and forms of carbon have been discovered and researched including ball shapes such as buckminsterfullerene and sheets such as graphene. Larger scale structures of carbon nanotubes, nanobuds and nanoribbons. Other unusual forms of carbon exist at high temperatures or extreme pressures. Around 350 hypotetical 3-periodic allotropes of carbon are known at the present time according to SACADA database, Diamond is a well known allotrope of carbon. The hardness and high dispersion of light of diamond make it useful for industrial applications and jewelry. Diamond is the hardest known natural mineral and this makes it an excellent abrasive and makes it hold polish and luster extremely well. No known naturally occurring substance can cut a diamond, except another diamond, the market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the characteristics of diamond, including clarity and color. This helps explain why 80% of mined diamonds are unsuitable for use as gemstones, the dominant industrial use of diamond is in cutting, drilling, grinding, and polishing. Most uses of diamonds in these technologies do not require large diamonds, in fact, diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications. Specialized applications include use in laboratories as containment for high pressure experiments, high-performance bearings, with the continuing advances being made in the production of synthetic diamond, future applications are beginning to become feasible. Garnering much excitement is the use of diamond as a semiconductor suitable to build microchips from. Each carbon atom in a diamond is covalently bonded to four other carbons in a tetrahedron and these tetrahedrons together form a 3-dimensional network of six-membered carbon rings, in the chair conformation, allowing for zero bond angle strain. This stable network of covalent bonds and hexagonal rings, is the reason that diamond is so strong.1 kJ/mol compared to graphite, graphite, named by Abraham Gottlob Werner in 1789, from the Greek γράφειν is one of the most common allotropes of carbon. Unlike diamond, graphite is an electrical conductor, thus, it can be used in, for instance, electrical arc lamp electrodes. Likewise, under conditions, graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the state for defining the heat of formation of carbon compounds
19.
Orbital hybridisation
–
In chemistry, hybridisation is the concept of mixing atomic orbitals into new hybrid orbitals suitable for the pairing of electrons to form chemical bonds in valence bond theory. Hybrid orbitals are very useful in the explanation of molecular geometry, although sometimes taught together with the valence shell electron-pair repulsion theory, valence bond and hybridisation are in fact not related to the VSEPR model. Chemist Linus Pauling first developed the theory in 1931 in order to explain the structure of simple molecules such as methane using atomic orbitals. In reality however, methane has four bonds of equivalent strength separated by the bond angle of 109. 5°. It gives a simple orbital picture equivalent to Lewis structures, hybridisation theory finds its use mainly in organic chemistry. Orbitals are a representation of the behaviour of electrons within molecules. In heavier atoms, such as carbon, nitrogen, and oxygen, hybrid orbitals are assumed to be mixtures of atomic orbitals, superimposed on each other in various proportions. For example, in methane, the C hybrid orbital which forms each carbon–hydrogen bond consists of 25% s character and 75% p character and is thus described as sp3 hybridised. Quantum mechanics describes this hybrid as an sp3 wavefunction of the form N, the ratio of coefficients is √3 in this example. Since the electron density associated with an orbital is proportional to the square of the wavefunction, the p character or the weight of the p component is N2λ2 = 3/4. The amount of p character or s character, which is decided mainly by orbital hybridisation, molecules with multiple bonds or multiple lone pairs can have orbitals represented in terms of sigma and pi symmetry or equivalent orbitals. The sigma and pi representation of Erich Hückel is the common one compared to the equivalent orbital representation of Linus Pauling. The two have mathematically equivalent total many-electron wave functions, and are related by a transformation of the set of occupied molecular orbitals. Hybridisation describes the bonding atoms from a point of view. For a tetrahedrally coordinated carbon, the carbon should have 4 orbitals with the symmetry to bond to the 4 hydrogen atoms. The carbon atom can also bond to four hydrogen atoms by an excitation of an electron from the doubly occupied 2s orbital to the empty 2p orbital, producing four singly occupied orbitals. The energy released by formation of two additional bonds more than compensates for the energy required, energetically favouring the formation of four C-H bonds. Quantum mechanically, the lowest energy is obtained if the four bonds are equivalent, a set of four equivalent orbitals can be obtained that are linear combinations of the valence-shell s and p wave functions, which are the four sp3 hybrids
20.
Diamond
–
Diamond is a metastable allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the rate from diamond to graphite is negligible at standard conditions. Diamond is renowned as a material with superlative physical qualities, most of which originate from the covalent bonding between its atoms. In particular, diamond has the highest hardness and thermal conductivity of any bulk material and those properties determine the major industrial application of diamond in cutting and polishing tools and the scientific applications in diamond knives and diamond anvil cells. Because of its extremely rigid lattice, it can be contaminated by very few types of impurities, such as boron, small amounts of defects or impurities color diamond blue, yellow, brown, green, purple, pink, orange or red. Diamond also has relatively high optical dispersion, most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers in the Earths mantle. Carbon-containing minerals provide the source, and the growth occurs over periods from 1 billion to 3.3 billion years. Diamonds are brought close to the Earths surface through deep volcanic eruptions by magma, Diamonds can also be produced synthetically in a HPHT method which approximately simulates the conditions in the Earths mantle. An alternative, and completely different growth technique is chemical vapor deposition, several non-diamond materials, which include cubic zirconia and silicon carbide and are often called diamond simulants, resemble diamond in appearance and many properties. Special gemological techniques have developed to distinguish natural diamonds, synthetic diamonds. The word is from the ancient Greek ἀδάμας – adámas unbreakable, the name diamond is derived from the ancient Greek αδάμας, proper, unalterable, unbreakable, untamed, from ἀ-, un- + δαμάω, I overpower, I tame. Diamonds have been known in India for at least 3,000 years, Diamonds have been treasured as gemstones since their use as religious icons in ancient India. Their usage in engraving tools also dates to early human history, later in 1797, the English chemist Smithson Tennant repeated and expanded that experiment. By demonstrating that burning diamond and graphite releases the same amount of gas, the most familiar uses of diamonds today are as gemstones used for adornment, a use which dates back into antiquity, and as industrial abrasives for cutting hard materials. The dispersion of light into spectral colors is the primary gemological characteristic of gem diamonds. In the 20th century, experts in gemology developed methods of grading diamonds, four characteristics, known informally as the four Cs, are now commonly used as the basic descriptors of diamonds, these are carat, cut, color, and clarity. A large, flawless diamond is known as a paragon and these conditions are met in two places on Earth, in the lithospheric mantle below relatively stable continental plates, and at the site of a meteorite strike. The conditions for diamond formation to happen in the mantle occur at considerable depth corresponding to the requirements of temperature and pressure
21.
Lonsdaleite
–
Lonsdaleite, also called hexagonal diamond in reference to the crystal structure, is an allotrope of carbon with a hexagonal lattice. In nature, it forms when meteorites containing graphite strike the Earth, the great heat and stress of the impact transforms the graphite into diamond, but retains graphites hexagonal crystal lattice. Lonsdaleite was first identified in 1967 from the Canyon Diablo meteorite, hexagonal diamond has also been synthesized in the laboratory by compressing and heating graphite either in a static press or using explosives. It has also produced by chemical vapor deposition, and also by the thermal decomposition of a polymer, poly, at atmospheric pressure, under argon atmosphere. It is translucent, brownish-yellow, and has an index of refraction of 2.40 to 2.41 and its hardness is theoretically superior to that of cubic diamond according to computational simulations but natural specimens exhibited somewhat lower hardness through a large range of values. The cause is speculated as being due to the samples having been riddled with lattice defects, a quantitative analysis of the X-ray diffraction data of lonsdaleite has shown that about equal amounts of hexagonal and cubic stacking sequences are present. Consequently, it has suggested that stacking disordered diamond is the most accurate structural description of lonsdaleite. According to the picture, Lonsdaleite has a hexagonal unit cell, related to the diamond unit cell in the same way that the hexagonal. The diamond structure can be considered to be made up of interlocking rings of six carbon atoms, in lonsdaleite, some rings are in the boat conformation instead. Lonsdaleite is simulated to be 58% harder than diamond on the face and to resist indentation pressures of 152 GPa. This is yet exceeded by IIa diamonds <111> tip hardness of 162 GPa, Lonsdaleite occurs as microscopic crystals associated with diamond in several meteorites, Canyon Diablo, Kenna, and Allan Hills 77283. It is also occurring in non-bolide diamond placer deposits in the Sakha Republic. Its presence in local deposits is claimed as evidence for the Tunguska event being caused by a meteor rather than by a cometary fragment. Aggregated diamond nanorod Glossary of meteoritics List of minerals List of minerals named after people Anthony, materials Science and Technology Division, Naval Research Laboratory website accessed 14 May 2006. Diamond no longer natures hardest material lonsdaleite 3D animation
22.
Graphite
–
Graphite, archaically referred to as plumbago, is a crystalline form of carbon, a semimetal, a native element mineral, and one of the allotropes of carbon. Graphite is the most stable form of carbon under standard conditions, therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. Highly ordered pyrolytic graphite or more correctly highly oriented pyrolytic graphite refers to graphite with a spread between the graphite sheets of less than 1°. The name graphite fiber is sometimes used to refer to carbon fibers or carbon fiber-reinforced polymer. Graphite occurs in rocks as a result of the reduction of sedimentary carbon compounds during metamorphism. It also occurs in rocks and in meteorites. Minerals associated with graphite include quartz, calcite, micas and tourmaline, in meteorites it occurs with troilite and silicate minerals. Small graphitic crystals in meteoritic iron are called cliftonite, Graphite is not mined in the United States, but U. S. production of synthetic graphite in 2010 was 134 kt valued at $1.07 billion. Graphite has a layered, planar structure, the individual layers are called graphene. In each layer, the atoms are arranged in a honeycomb lattice with separation of 0.142 nm. Atoms in the plane are bonded covalently, with three of the four potential bonding sites satisfied. The fourth electron is free to migrate in the plane, making graphite electrically conductive, however, it does not conduct in a direction at right angles to the plane. Bonding between layers is via weak van der Waals bonds, which allows layers of graphite to be easily separated, the two known forms of graphite, alpha and beta, have very similar physical properties, except for that the graphene layers stack slightly differently. The alpha graphite may be flat or buckled. The alpha form can be converted to the form through mechanical treatment. The acoustic and thermal properties of graphite are highly anisotropic, since phonons propagate quickly along the tightly-bound planes, graphites high thermal stability and electrical and thermal conductivity facilitate its widespread use as electrodes and refractories in high temperature material processing applications. However, in oxygen containing atmospheres graphite readily oxidizes to form CO2 at temperatures of 700 °C, Graphite is an electric conductor, consequently, useful in such applications as arc lamp electrodes. It can conduct electricity due to the vast electron delocalization within the carbon layers and these valence electrons are free to move, so are able to conduct electricity
23.
Graphene
–
Graphene is an allotrope of carbon in the form of a two-dimensional, atomic-scale, hexagonal lattice in which one atom forms each vertex. It is the structural element of other allotropes, including graphite, charcoal. It can be considered as a large aromatic molecule, the ultimate case of the family of flat polycyclic aromatic hydrocarbons. It is about 200 times stronger than the strongest steel and it efficiently conducts heat and electricity and is nearly transparent. Graphene shows a large and nonlinear diamagnetism, greater than graphite, scientists have theorized about graphene for years. It has unintentionally been produced in small quantities for centuries, through the use of pencils and it was originally observed in electron microscopes in 1962, but it was studied only while supported on metal surfaces. The material was later rediscovered, isolated, and characterized in 2004 by Andre Geim, research was informed by existing theoretical descriptions of its composition, structure, and properties. This work resulted in the two winning the Nobel Prize in Physics in 2010 for groundbreaking experiments regarding the material graphene. The global market for graphene reached $9 million by 2012 with most sales in the semiconductor, electronics, battery energy, Graphene is a combination of graphite and the suffix -ene, named by Hanns-Peter Boehm, who described single-layer carbon foils in 1962. The term was used in early descriptions of carbon nanotubes, as well as for epitaxial graphene. Graphene can be considered an infinite alternant polycyclic aromatic hydrocarbon, the IUPAC compendium of technology states, previously, descriptions such as graphite layers, carbon layers, or carbon sheets have been used for the term graphene. It is incorrect to use for a single layer a term includes the term graphite. The term graphene should be used only when the reactions, structural relations or other properties of individual layers are discussed and this definition is narrower than the IUPAC definition and refers to cloven, transferred and suspended graphene. Other forms such as graphene grown on various metals, can become free-standing if, for example, in 1859 Benjamin Collins Brodie became aware of the highly lamellar structure of thermally reduced graphite oxide. The structure of graphite was identified in 1916 by the method of powder diffraction. It was studied in detail by Kohlschütter and Haenni in 1918 and its structure was determined from single-crystal diffraction in 1924. The theory of graphene was first explored by Wallace in 1947 as a point for understanding the electronic properties of 3D graphite. The emergent massless Dirac equation was first pointed out by Semenoff, DiVincenzo, Semenoff emphasized the occurrence in a magnetic field of an electronic Landau level precisely at the Dirac point
24.
Carbon nanotube
–
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics and other fields of materials science and technology. Owing to the exceptional strength and stiffness, nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000,1. In addition, owing to their thermal conductivity, mechanical. For instance, nanotubes form a portion of the material in some baseball bats, golf clubs. Nanotubes are members of the fullerene structural family and their name is derived from their long, hollow structure with the walls formed by one-atom-thick sheets of carbon, called graphene. Nanotubes are categorized as single-walled nanotubes and multi-walled nanotubes, individual nanotubes naturally align themselves into ropes held together by van der Waals forces, more specifically, pi-stacking. Applied quantum chemistry, specifically, orbital hybridization best describes chemical bonding in nanotubes, the chemical bonding of nanotubes is composed entirely of sp2 bonds, similar to those of graphite. These bonds, which are stronger than the sp3 bonds found in alkanes and diamond, most single-walled nanotubes have a diameter of close to 1 nanometer, and can be many millions of times longer. The structure of a SWNT can be conceptualized by wrapping a one-atom-thick layer of graphite called graphene into a seamless cylinder, the way the graphene sheet is wrapped is represented by a pair of indices. The integers n and m denote the number of unit vectors along two directions in the crystal lattice of graphene. If m =0, the nanotubes are called zigzag nanotubes, and if n = m, the diameter of an ideal nanotube can be calculated from its indices as follows d = a π =78.3 p m, where a =0.246 nm. SWNTs are an important variety of carbon nanotube because most of their properties change significantly with the values, in particular, their band gap can vary from zero to about 2 eV and their electrical conductivity can show metallic or semiconducting behavior. Single-walled nanotubes are likely candidates for miniaturizing electronics, the most basic building block of these systems is the electric wire, and SWNTs with diameters of an order of a nanometer can be excellent conductors. One useful application of SWNTs is in the development of the first intermolecular field-effect transistors, the first intermolecular logic gate using SWCNT FETs was made in 2001. A logic gate requires both a p-FET and an n-FET, because SWNTs are p-FETs when exposed to oxygen and n-FETs otherwise, it is possible to expose half of an SWNT to oxygen and protect the other half from it. The resulting SWNT acts as a not logic gate with both p and n-type FETs in the same molecule, prices for single-walled nanotubes declined from around $1500 per gram as of 2000 to retail prices of around $50 per gram of as-produced 40–60% by weight SWNTs as of March 2010. As of 2016 the retail price of as-produced 75% by weight SWNTs were $2 per gram, SWNTs are forecast to make a large impact in electronics applications by 2020 according to the The Global Market for Carbon Nanotubes report
25.
Carbon nanobud
–
In nanotechnology, a carbon nanobud is a material that combines carbon nanotubes and spheroidal fullerenes, both allotropes of carbon, in the same structure, forming buds attached to the tubes. Carbon nanobuds were discovered and synthesized in 2006, in this new material, fullerenes are covalently bonded to the outer sidewalls of the underlying nanotube. Consequently, nanobuds exhibit properties of carbon nanotubes and fullerenes. For instance, the properties and the electrical conductivity of the nanobuds are similar to those of corresponding carbon nanotubes. However, because of the reactivity of the attached fullerene molecules. Owing to the number of highly curved fullerene surfaces acting as electron emission sites on conductive carbon nanotubes. Randomly oriented nanobuds have already been demonstrated to have a low work function for field electron emission. Reported test measurements show field thresholds of about 0.65 V/μm, the electron transport properties of certain nanobud classes have been treated theoretically. The study shows that electrons indeed pass to the neck and bud region of the nanobud system, canatu Oy, a Finnish company, claims the intellectual property rights for nanobud material, its synthesis processes, and several applications. Properties such as chemical reactivity, good dispersion and variable band gap electronic structure suggest wide applicability of nanobuds, as the production processes are scalable, the nanobud applications may have industrial importance. Several theoretical works also mentioned the magnetism in nanobuds, canatu has demonstrated curved and highly foldable touch screens made with nanobuds
26.
Glassy carbon
–
Glass-like carbon, often called glassy carbon or vitreous carbon, is a non-graphitizing, or nongraphitizable, carbon which combines glassy and ceramic properties with those of graphite. The names glassy carbon and vitreous carbon have been introduced as trademarks, therefore, Vitreous carbon can also be produced as a foam. It is then called reticulated vitreous carbon and this foam was first developed in the mid to late 1960s as a thermally insulating, microporous glassy carbon electrode material. RVC foam is a strong, inert, electrically and thermally conductive, due to these characteristics, the most widespread scientific use of RVC is in electrochemistry. Glassy carbon was first observed in the laboratories of The Carborundum Company, Manchester, UK, in the mid-1950s by Bernard Redfern and he noticed that Sellotape he used to hold ceramic samples in a furnace maintained a sort of structural identity after firing in an inert atmosphere. He searched for a matrix to mirror a diamond structure and discovered a resole resin that would, with special preparation. Using this phenolic resin, crucibles were produced, crucibles were distributed to organisations such as UKAEA Harwell. Bernard Redfern left The Carborundum Co. which officially wrote off all interests in the glassy carbon invention, while working at the Plessey Company laboratory in Towcester, UK, Redfern received a glassy carbon crucible for duplication from UKAEA. He identified it as one he had made from markings he had engraved into the uncured precursor prior to carbonisation. The Plessey Company set up a laboratory first in a previously used to make briar pipes, in Litchborough, UK. Caswell became the Plessey Research Centre and then the Allen Clark Research Centre, Glassy carbon arrived at the Plessey Company Limited as a fait accompli. Redfern was assigned J. C. Lewis, as a laboratory assistant, F. C. Cowlard was assigned to Redferns department later, as a laboratory administrator. Cowlard was an administrator who previously had some association with Silane, neither he nor Lewis had any previous connection with glassy carbon. The contribution of Bernard Redfern to the invention and production of glassy / Vitreous carbon is acknowledged by his co-authorship of early articles, but references to Redfern were not obvious in subsequent publications by Cowlard and Lewis. Original boat crucibles, thick section rods and precursor samples exist and this came after the rescinded British patent. This prior art is not referenced in US patent 4,668,496,26 May 1987 for Vitreous Carbon, patents were filed Bodies and shapes of carbonaceous materials and processes for their production and the name Vitreous Carbon presented to the product by the son of Redfern. Glassy/Vitreous Carbon was under investigation used for components for thermonuclear detonation systems, large sections of the precursor material were produced as castings, moldings or machined into a predetermined shape. Large crucibles and other forms were manufactured, carbonisation took place in two stages
27.
Carbide-derived carbon
–
Carbide-derived carbon, also known as tunable nanoporous carbon, is the common term for carbon materials derived from carbide precursors, such as binary, or ternary carbides, also known as MAX phases. CDCs have also derived from polymer-derived ceramics such as Si-O-C or Ti-C. CDCs can occur in structures, ranging from amorphous to crystalline carbon, from sp2- to sp3-bonded. Among carbon materials, microporous CDCs exhibit some of the highest reported specific surface areas, by varying the type of the precursor and the CDC synthesis conditions, microporous and mesoporous structures with controllable average pore size and pore size distributions can be produced. Depending on the precursor and the conditions, the average pore size control can be applied at sub-Angstrom accuracy. The production of SiCl4 by high temperature reaction of Chlorine gas with Silicon Carbide was first patented in 1918 by Otis Hutchins, the solid porous carbon product was initially regarded as a waste byproduct until its properties and potential applications were investigated in more detail in 1959 by Walter Mohun. Most recently, research activities have centered on optimized CDC synthesis, historically, various terms have been used for CDC, such as mineral carbon or nanoporous carbon. Later, a more adequate nomenclature introduced by Yury Gogotsi was adopted that clearly denotes the precursor, for example, CDC derived from silicon carbide has been referred to as SiC-CDC, Si-CDC, or SiCDC. Recently, it was recommended to adhere to a unified precursor-CDC-nomenclature to reflect the composition of the precursor. CDCs have been synthesized using several chemical and physical synthesis methods, most commonly, dry chlorine treatment is used to selectively etch metal or metalloid atoms from the carbide precursor lattice. The term chlorine treatment is to be preferred over chlorination as the product, metal chloride, is the discarded byproduct. This method is implemented for commercial production of CDC by Skeleton in Estonia, hydrothermal etching has also been used for synthesis of SiC-CDC which yielded a route for porous carbon films and nanodiamond synthesis. The most common method for producing porous carbide-derived carbons involves high-temperature etching with halogens, temperatures above 1000 °C result in predominantly graphitic carbon and an observed shrinkage of the material due to graphitization. The linear growth rate of the carbon product phase suggests a reaction-driven kinetic mechanism. A high mass transport condition facilitates the removal of the chloride, most produced CDCs exhibit a prevalence of micropores and mesopores, with specific distributions affected by carbide precursor and synthesis conditions. Hierarchic porosity can be achieved by using polymer-derived ceramics with or without utilizing a templating method, templating yields an ordered array of mesopores in addition to the disordered network of micropores. It has been shown that the crystal structure of the carbide is the primary factor affecting the CDC porosity. In general, a spacing between carbon atoms in the lattice correlates with an increase in the average pore diameter
28.
Atomic carbon
–
Atomic carbon, also called monocarbon, is an inorganic chemical with the chemical formula C. It is a gas that exists above 3,642 °C. The trivial name monocarbon is the preferred IUPAC name, the systematic names, methanediylidene and carbon, valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, respectively. Methanediylidene is viewed as methane with all four hydrogen atoms removed, by default, this name pays no regard to the radicality of the atomic carbon. Although, in more specific context, it can also name the non-radical excited states. Many of atomic carbons electronic states lie relatively close to each other, the ground state is a triplet radical with two unpaired electrons, and the first two excited states are a singlet non-radical and a singlet radical with two unpaired electrons. A sample of atomic carbon exists as a mixture of electronic states even at room temperature, Atomic carbon can accept two such ligands. The methylylidyne group can also donate an electron-pair to a centre by adduction, M + → Because of this donation of the electron-pair. Since a Lewis base is also Brønsted base, atomic carbon can in theory be protonated to form a conjugate acid, Atomic carbon is not stable in aqueous solution, as it is rapidly oxidized to form carbon monoxide or formaldehyde. Atomic carbon is reactive, most reactions are very exothermic. They are generally carried out in the gas phase at liquid nitrogen temperatures, insertion into carbon -carbon double bonds to form a cyclopropylidene which undergoes ring-opening, a simple example being insertion into an alkene to form a cumulene. With water insertion into the O-H bond forms the carbene, H-C-OH that rearranges to formaldehyde, normally, a sample of atomic carbon exists as a mixture of excited states in addition to the ground-state in thermodynamic equilibrium. Each state contributes differently to the mechanisms that can take place. The diradical ground-state normally undergoes abstraction reactions, Atomic carbon has been used to generate true carbenes by the abstraction of oxygen atoms from carbonyl groups, R2C=O +, C, → R2C, + CO Carbenes formed in this way will exhibit true carbenic behaviour. Carbenes prepared by methods such as diazo compounds, might exhibit properties better attributed to the diazo compound used to make the carbene. This is important from an understanding of true carbene behaviour perspective. This very short lived species is created by passing a current through two adjacent carbon rods, generating an electric arc. Atomic carbon is generated in the process, professor Phil Shevlin has done the principal work in the field based at Auburn University in the USA
29.
Diatomic carbon
–
Diatomic carbon, also called dicarbon, is an inorganic chemical with the chemical formula C=C. It is a gas that exists above 3,642 °C ). It occurs in carbon vapor, for example in electric arcs, in comets, stellar atmospheres and the interstellar medium, dicarbon is the preferred IUPAC name. The systematic names ethenediylidene and dicarbon, valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, ethenediylidene is viewed as ethylene with four hydrogen atoms removed. By default, this name pays no regard to the state of the diatomic carbon. Molecular orbital theory shows that there are two sets of paired electrons in a degenerate pi bonding set of orbitals and this gives a bond order of 2, meaning that there should exist a double bond between the two carbons in a C2 molecule. However, a recent paper by S. Shaik has suggested that a quadruple bond exists in diatomic carbon, M. Zhang has proved from CASSCF that the quadruple bond based Molecular orbital theory is also reasonable. Bond dissociation energies of B2, C2, and N2 show increasing BDE, indicating single, double, C2 is a component of carbon vapor. One paper estimates that carbon vapor is around 28% diatomic, the light of fainter comets mainly originates from the emission of diatomic carbon. An example is C/2014 Q2, where there are lines of C2 light, mostly in the visible spectrum. The triplet state has a bond length than the singlet state. Diatomic carbon will react with acetone and acetaldehyde to produce acetylene by two different pathways, triplet C2 molecules will react through an intermolecular pathway, which is shown to exhibit radical character. The intermediate for this pathway is the ethylene radical and its abstraction is correlated with bond energies. Singlet C2 molecules will react through an intramolecular, nonradical pathway in two hydrogen atoms will be taken away from one molecule. The intermediate for this pathway is singlet vinylidene, the singlet reaction can happen through a 1, 1-diabstraction or a 1, 2-diabstraction. This reaction is insensitive to isotope substitution, the different abstractions are possibly due to the spatial orientations of the collisions rather than the bond energies. Singlet C2 will also react with alkenes, acetylene is a major product, however, it appears C2 will insert into carbon-hydrogen bonds. C2 is 2.5 times more likely to insert into a group as into methylene groups
30.
Tricarbon
–
Tricarbon is an inorganic compound with the chemical formula C2. It is a gas that only persists in dilution or solution as an adduct. It is one of the simplest unsaturated carbenes and it is a small carbon cluster first spectroscopically observed in the beginning 20th century in the tail of a comet by William Huggins and subsequently identified in stellar atmospheres. Tricarbon can be found in space and can be produced in the laboratory by a process called laser ablation. Small carbon clusters like tricarbon and dicarbon are regarded as soot precursors and are implicated in the formation of industrial diamonds. The ionization potential is determined experimentally at 11 to 13.5 electronvolts, in contrast to the linear tricarbon molecule the C3+ cation is bent. C3 has also identified as a transient species in various combustion reactions. The generation of C3 was investigated by Professor Emeritus Philip S. Skell of Pennsylvania State University in the 1960s, the systematic names 1λ2, 3λ2-propadiene, and μ-carbidodicarbon, valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, respectively. By default, these names pay no regard to the radicality of the tricarbon molecule, hydrocarbons Alkenes List of molecules in interstellar space Cyclopropatriene Gaydon, Alfred G. Wolfhard, Hans G. Flames, their structure, radiation and temperature. Hinkle, Kenneth W. Keady, John J. Bernath, Peter F. Detection of C3 in the Circumstellar Shell of IRC+10216
31.
Penta-graphene
–
Penta-graphene is a carbon allotrope composed entirely of carbon pentagons and resembling the Cairo pentagonal tiling. Penta-graphene was proposed in 2014 on the basis of analyses and simulations, further calculations showed that it is unstable in its pure form, but can be stabilized by hydrogenation. Owing to its configuration, penta-graphene has an unusually negative Poisson’s ratio and very high ideal strength believed to exceed that of a similar material. Penta-graphene contains both sp2 and sp3 hybridized carbon atoms, contrary to graphene, which is a good conductor of electricity, penta-graphene is an insulator with an indirect band gap of 4. 1–4.3 eV. Its hydrogenated form is called penta-graphane and it has a diamond-like structure with sp3 and no sp2 bonds, and therefore a wider band gap than penta-graphene. Chiral penta-graphene nanotubes have also studied as metastable allotropes of carbon
32.
Activated carbon
–
Activated carbon, also called activated charcoal, is a form of carbon processed to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Activated is sometimes substituted with active, due to its high degree of microporosity, just one gram of activated carbon has a surface area in excess of 3,000 m2, as determined by gas adsorption. An activation level sufficient for useful application may be attained solely from high surface area, activated carbon is usually derived from charcoal and is sometimes utilized as biochar. Those derived from coal and coke are referred as activated coal, one major industrial application involves use of activated carbon in the metal finishing field. It is very widely employed for purification of electroplating solutions, for example, it is a main purification technique for removing organic impurities from bright nickel plating solutions. A variety of chemicals are added to plating solutions for improving their deposit qualities and for enhancing properties like brightness, smoothness, ductility. Due to passage of current and electrolytic reactions of anodic oxidation and cathodic reduction. Their excessive build up can adversely affect the quality and physical properties of deposited metal. Activated carbon treatment removes such impurities and restores plating performance to the desired level, activated carbon is used to treat poisonings and overdoses following oral ingestion. Tablets or capsules of activated carbon are used in countries as an over-the-counter drug to treat diarrhea, indigestion. However, it is ineffective for a number of poisonings including strong acids or alkali, cyanide, iron, lithium, arsenic, incorrect application results in pulmonary aspiration, which can sometimes be fatal if immediate medical treatment is not initiated. During early implementation of the 1974 Safe Drinking Water Act in the USA, activated carbon is also used for the measurement of radon concentration in air. Activated carbon is a substance used by organic farmers in both livestock production and wine making. In livestock production it is used as a pesticide, animal feed additive, processing aid, benefits in case of animal feed additive are questionable. In organic winemaking, activated carbon is allowed for use as an agent to absorb brown color pigments from white grape concentrates. Activated carbon filters can be used to filter vodka and whiskey of organic impurities which can affect color, taste, research is being done testing various activated carbons ability to store natural gas and hydrogen gas. The porous material acts like a sponge for different types of gases, the gas is attracted to the carbon material via Van der Waals forces. Some carbons have been able to achieve bonding energies of 5–10 kJ per mol, the gas may then be desorbed when subjected to higher temperatures and either combusted to do work or in the case of hydrogen gas extracted for use in a hydrogen fuel cell
33.
Carbon black
–
Carbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of carbon that has a high surface-area-to-volume ratio. It is dissimilar to soot in its much higher surface-area-to-volume ratio, however, carbon black is widely used as a model compound for diesel soot for diesel oxidation experiments. Carbon black is used as a reinforcing filler in tires. In plastics, paints, and inks carbon black is used as a color pigment, the current International Agency for Research on Cancer evaluation is that, Carbon black is possibly carcinogenic to humans. Short-term exposure to concentrations of carbon black dust may produce discomfort to the upper respiratory tract. Total production was around 8,100,000 metric tons in 2006, the most common use of carbon black is as a pigment and reinforcing phase in automobile tires. Carbon black also helps conduct heat away from the tread and belt area of the tire, reducing thermal damage, the high tinting strength and stability of carbon black has also provided use in coloring of resins and films. About 20% of world production goes into belts, hoses, the balance is mainly used as a pigment in inks, coatings and plastics. For example, it is added to polypropylene because it absorbs ultraviolet radiation, Carbon black from vegetable origin is used as a food coloring, in Europe known as additive E153. It is approved for use as additive 153 in Australia and New Zealand but has been banned in the US, Carbon black has been used in various applications for electronics. As a good conductor of electricity, carbon black is used as a mixed in plastics, elastomer, films, adhesives. Application of carbon black as an agent has provided uses as an additive for fuel caps. Additionally, the color pigment carbon black has been used in food. It is used in multi-layer UHT milk bottles in the US, parts of Europe and Asia, and South Africa, the Canadian Government’s assessment in 2011 concluded that carbon black should continue to be used in products – including food packaging for consumers – in Canada. The highest volume use of black is as a reinforcing filler in rubber products. It is used often in the Aerospace industry in elastomers for aircraft vibration control components such as engine mounts, practically all rubber products where tensile and abrasion wear properties are crucial use carbon black, so they are black in color. Traditionally silica fillers had worse abrasion wear properties, but the technology has improved to a point where they can match carbon black abrasion performance
34.
Charcoal
–
Charcoal is a lightweight, black residue, consisting of carbon and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis- the heating of wood or other substances in the absence of oxygen, the whole pile is covered with turf or moistened clay. The firing is begun at the bottom of the flue, the success of the operation depends upon the rate of the combustion. The operation is so delicate that it was left to colliers. They often lived alone in small huts in order to tend their wood piles, for example, in the Harz Mountains of Germany, charcoal burners lived in conical huts called Köten which are still much in evidence today. The massive production of charcoal was a cause of deforestation. The increasing scarcity of easily harvested wood was a factor behind the switch to fossil fuel equivalents, mainly coal. Charcoal made at 300 °C is brown, soft and friable, and readily inflames at 380 °C, made at higher temperatures it is hard and brittle, in Finland and Scandinavia, the charcoal was considered the by-product of wood tar production. The best tar came from pine, thus pinewoods were cut down for tar pyrolysis, the residual charcoal was widely used as substitute for metallurgical coke in blast furnaces for smelting. Tar production led to deforestation, it has been estimated all Finnish forests are younger than 300 years. The end of tar production at the end of the 19th century resulted in rapid re-forestation, the charcoal briquette was first invented and patented by Ellsworth B. A. Zwoyer of Pennsylvania in 1897 and was produced by the Zwoyer Fuel Company. The process was popularized by Henry Ford, who used wood. Ford Charcoal went on to become the Kingsford Company, Charcoal has been made by various methods. The traditional method in Britain used a clamp and this is essentially a pile of wooden logs leaning against a chimney. The chimney consists of 4 wooden stakes held up by some rope, the logs are completely covered with soil and straw allowing no air to enter. It must be lit by introducing some burning fuel into the chimney, if the soil covering gets torn by the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air from entering, the true art of this production method is in managing the sufficient generation of heat, and its transfer to wood parts in the process of being carbonised. A strong disadvantage of this method is the huge amount of emissions that are harmful to human health
35.
Carbon fibers
–
Carbon fibers or carbon fibres are fibers about 5–10 micrometres in diameter and composed mostly of carbon atoms. Several thousand carbon fibers are bundled together to form a tow, however, they are relatively expensive when compared with similar fibers, such as glass fibers or plastic fibers. Carbon fibers are usually combined with materials to form a composite. When combined with a resin and wound or molded it forms carbon-fiber-reinforced polymer which has a very high strength-to-weight ratio. However, carbon fibers are also composited with other materials, such as graphite, to form carbon-carbon composites, in 1860 Joseph Swan produced carbon fibres for the first time, for use in light bulbs. In 1880, Lewis Latimer developed a reliable carbon wire filament for the incandescent light bulb, in 1958, Roger Bacon created high-performance carbon fibers at the Union Carbide Parma Technical Center, now GrafTech International Holdings, Inc. located outside of Cleveland, Ohio. Those fibers were manufactured by heating strands of rayon until they carbonized and this process proved to be inefficient, as the resulting fibers contained only about 20% carbon and had low strength and stiffness properties. In the early 1960s, a process was developed by Dr. Akio Shindo at Agency of Industrial Science and Technology of Japan and this had produced a carbon fiber that contained about 55% carbon. In 1960 Richard Millington of H. I. Thompson Fiberglas Co. developed a process for producing a carbon content fiber using rayon as a precursor. Watt, L. N. Phillips, and W. Johnson at the Royal Aircraft Establishment at Farnborough, the process was patented by the UK Ministry of Defence, then licensed by the NRDC to three British companies, Rolls-Royce already making carbon fiber, Morganite, and Courtaulds. Unfortunately, the blades proved vulnerable to damage from bird impact and this problem and others caused Rolls-Royce such setbacks that the company was nationalized in 1971. The carbon-fiber production plant was sold off to form Bristol Composites, in the late 1960s, the Japanese took the lead in manufacturing PAN-based carbon fibers. The 1970 joint technology agreement allowed Union Carbide to manufacture the Japan’s Toray Industries superior product, Morganite decided that carbon-fiber production was peripheral to its core business, leaving Courtaulds as the only big UK manufacturer. However Courtauldss big advantage as manufacturer of the Courtelle precursor now became a weakness, the investment did not generate the anticipated returns, leading to a decision to pull out of the area and Courtaulds ceased carbon-fiber production in 1991. Ironically the one surviving UK carbon-fiber manufacturer continued to thrive making fiber based on Courtauldss precursor, inverness-based RK Carbon Fibres Ltd concentrated on producing carbon fiber for industrial applications, removing the need to compete at the quality levels reached by overseas manufacturers. During the 1960s, experimental work to find alternative raw materials led to the introduction of carbon fibers made from a petroleum pitch derived from oil processing and these fibers contained about 85% carbon and had excellent flexural strength. These companies included Hercules, BASF and Celanese USA and Akzo in Europe, since the late 1970s, further types of carbon fiber yarn entered the global market, offering higher tensile strength and higher elastic modulus. For example, T400 from Toray with a strength of 4,000 MPa and M40
36.
Aggregated diamond nanorod
–
Aggregated diamond nanorods, or ADNRs, are a nanocrystalline form of diamond, also known as nanodiamond or hyperdiamond. Nanodiamond was convincingly demonstrated to be produced by compression of graphite in 2003, the same group later described ADNRs as having a hardness and Youngs modulus comparable to that of natural diamond, but with superior wear resistance. A <111> surface of pure diamond has a value of 167±6 GPa when scratched with a nanodiamond tip. However, the test only works properly with a tip made of material than the sample being tested. This means that the value for nanodiamond is likely somewhat lower than 310 GPa. ADNRs are produced by compressing fullerite powder — a solid form of allotropic carbon fullerene — with two somewhat similar methods, one uses a diamond anvil cell and applied pressure ~37 GPa without heating the cell. In another method, fullerite is compressed to lower pressures and then heated to a temperature in the range of 300 to 2,500 K, extreme hardness of what now appears likely to have been nanodiamonds was reported by researchers in the 1990s. The material is a series of interconnected diamond nanorods, with diameters of between 5 and 20 nanometres and lengths of around 1 micrometre each. Nanodiamond aggregates ca.1 mm in size also form in nature, from graphite upon meteoritic impact, adamant Carbon nanotube Diamond Fullerite Lonsdaleite Mohs scale of mineral hardness Rhenium diboride Superhard material The invention of aggregated diamond nanorods at Physorg. com Michelle Jeandron
Media related to Fullerenes at Wikimedia Commons