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New allotropic carbon forms — fullerenes — have been opened in 1985 [1], however the scientific interest for studying the fullerenes started after the invention in 1990 of a way of their production in macroscopical amounts [2] and especially after award in 1996 of the Nobel Prize in chemistry for opening the fullerenes. Interest for the researching of the fullerenes is caused by a variety of the new physical and chemical phenomena occurring at participation of the fullerenes, and the unique perspectives of the usage the new class of the materials created on their base [3, 4, 5].

Fullerenes and similar to fullerenes structures

Fullerenes — carbon clasters with even, more than 20, quantity of the atoms of the carbon forming three connections with each other [6]. Atoms in molecules of the fullerenes are located on a sphere or spheroid surface in tops of Hexagons and the Pentagons. Examples of the fullerenes are showed at the picture. 1. Fullerenes with the amount of atoms more than 70 (for example, C76, C78, C84) they called – the highest fullerenes.

Pic. 1. Some examples of the fullerenes

Molecule C60 possesses the highest symmetry among the fullerenes and the greatest stability. Each atom of carbon in a molecule is situated at the tops of two Hexagons and one Pentagon. The valence electrons of each atom are in sp2-hybridized states similar to the states of the electrons in graphite [7].

Fullerenes are practically insoluble in polar solvents types like alcohol, acetone, tetrahydrofuran, are slightly soluble in normal alkanes (pentane, hexane, decane). They dissolve the best way in liquids, for which is correlation specific enthalpy of evaporation to specific volume of a molecule of the solvent is close to corresponding value for molecule C60 (~100 kal/sm3) [8], for example, in benzol and toluene. The behaviour of the fullerenes in solutions has difficult . For example, solubility of the fullerene in the normal decalin, consisting of cis-and fumaroid forms in the correlation 3:7, is much more than solubilities in each of forms separately.

Molecules of the fullerenes are strong oxidizers cause they possess high electronegativity and are capable to attach to itself to six free electrons.

Carbon nanotubes are represent graphene the grids rolled up into the tubes, and can be opened and closed (Pic. 2), one-wall, double-walled and multiwall with the distance between walls about 0,35 nanometers. At the ends of the closed nanotubes besides hexagon cells, characteristic for black lead structure, there are situated the pentagonal cells.

Pic. 2. Carbon nanotubes, closed from one end

Zone structure of the one-wall carbon of the nanotubes is defined by their diameter and angle between a turning direction of the nanotube and a direction in which the next hexagons have the general side. Carbon of the nanotube can be conductors or semiconductors. An external magnetic field capablly to change width of the forbidden zone of a semi-conductor tube and even to bring it in a conductive condition. Conductivity of the carbon nanotubes, alloyed by potassium or bromine, at 300 K exceeds conductivity of the pure nanotubes more, than 30 times [9]. Carbon tubes are extremely strong and elastic. Their elastic moduls makes 0,40—3,7 TPa [10].

Endofullerens which are situated inside a molecule of the fullerene it is placed one or several not carbon atoms (pic. 3).

Pic. 3. A molecule of the endofullerene

Ultradispersed carbon aggregates (UDCA)— associates of the carbon clasters. UDCA are precipitate out by the variety of a structure. Among elements of associates there can be the most different structures, including chained, single-layered, multilayered ("bulbous").

Production of the fullereneconsists materials.

 

Synthesis of the fullerenes and UDCA

The most effective ways of the production of the fullerenes are technologies with the use of the electrical arc installations [2]: fullerenes are the product of the thermal dispersion of the graphite anode in helium atmosphere with the pressure 100—150 тorr.

In the Republic Belorussia was created the automated technological complex of the production of the fullerenes, which allow to produce ten grams of the fullerens for one shift [11]. The creation of complex made to work out the new technical decisions on all technological chain — from a choice of raw materials, production of the fullerene containing carbon black, division fullerens and UDCA to packing, storage and diagnostics of the received products (pic. 4) [12, 13, 14, 15]. Technology optimisation at a reception stage fullerene containing carbon black is provided with a choice and automatic stabilisation of a mode of arc discharge, electrode separation, pressure of the noble gas and a mode of its circulation. The yield of the fullerens is depends on fusion temperature, frequency of collisions small carbon clusters and the conditions of cooling of the synthesised molecules.

 

Identification of the received products

To analyses the quality of the production and its identification there are a number of methods of the analytical analyses.

Selection of articles about fullerens and nanotechnologies

More info you can find here:
The Discovery and Applications of Fullerenes
Big family of carbone. Fullerenes.