Crystal carbon allotropes

The different structures of the carbon allotropes lead to widely different properties. Because of its three-dimensional network of strong single bonds that tie all atoms in a crystal together, diamond is the hardest known substance. In addition to its use in jewelry, diamond is widely used industrially for the tips of saw blades... 

One may expect that future work on the electrochemistry of diamond should take two paths, namely, an extensive investigation (search for new processes and applications of the carbon allotropes in the electrochemical science and engineering) and intensive one (elucidation of the reaction mechanisms, revealing the effects of crystal structure and semiconductor properties on the electrochemical behavior of diamond and related materials). It is expected that better insight into these effects will result in the development of standard procedures for thin-film-electrodes growth, their characterization, and surface preparation. 

Carbon Allotropes.—Thermodynamic functions of single-crystal graphite have been assessed in the t emperature range 0—3000 K.7 The experimental specific heats have been described by a computer-fitted single equation enthalpies, entropies, and free energies have also been calculated. 

One of the most controversial research topics in modern carbon science concerns the thermodynamically stable existence of an sp-hybridized linear carbon chain allotrope called carbyne [1]. Acceptance by the scientific community of this alleged carbon allotrope as the third form of carbon would be much easier if single crystals of carbyne existed which were large enough to permit determination of their crystal structure by x-ray... 

Raman spectroscopy is widely used as a diagnostic tool for the evaluation of diamond crystals and CVD diamond films. The technique is popular because each carbon allotrope displays a clearly identifiable Raman signature, it is nondestructive (when the correct laser irradiation parameters are chosen), requires little or no specimen preparation, and can be made confocal so that micrometer volumes can be sampled. Raman scattering from single-crystal, CVD diamond films, and ND has recently been reviewed in Refs. 87,88. 

A number of chemical elements, mainly oxygen and carbon but also others, such as tin, phosphorus, and sulfur, occur naturally in more than one form. The various forms differ from one another in their physical properties and also, less frequently, in some of their chemical properties. The characteristic of some elements to exist in two or more modifications is known as allotropy, and the different modifications of each element are known as its allotropes. The phenomenon of allotropy is generally attributed to dissimilarities in the way the component atoms bond to each other in each allotrope either variation in the number of atoms bonded to form a molecule, as in the allotropes oxygen and ozone, or to differences in the crystal structure of solids such as graphite and diamond, the allotropes of carbon. 

The allotropy of carbon is due to variations in the crystal structure of the element. There are three allotropes of carbon graphite, diamond, and... 

If you stick to the definition of an allotrope being a modification of an element characterized by its x-ray crystal structure. Otherwise carbon may have more modifications, when counting all the different fullerenes and carbon nanotubes as allotropes. 

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