Graphitic synthesis

Nishihara, H. Harada, H. Tateishi, M. Ohashi, K. Aramaki, K. Graphite synthesis by electrochemical reduction of hexachlorobuta-l,3-diene. J. Chem. Soc. Faraday Trans. 1991, 87, 1187-1192. 

Goh, Munju et al. From helical polyacetylene to helical graphite synthesis in the chiral nematic liquid crystal field and morphology-retaining carbonisation. Chemical Society Reviews. 2010, 39, 2466-2476. 

Yakovlev AV, Finaenov AI, Zabud kov SL, Yakovleva EV. Thermally expanded graphite synthesis, properties, and prospects for use. Russ J Appl Chem 2006 79(11) 1741-51. 

Since CVD diamond is synthesized under conditions in which graphite synthesis is competitive, in many cases, a non diamond component may be incorporated in its amorphous form. The film quality was confirmed by Raman spectroscopy because it is very sensitive to graphitic and amorphous carbon (a C) components the Raman scattering intensity of graphite or a C is about 30 times greater than that of diamond. Raman spectroscopic measurements were carried out using an Ar+ laser (wavelength =... 

Interest in the synthesis of diamond [7782-40-3] was first stimulated by Lavoisier s discovery that diamond was simply carbon it was also observed that diamond, when heated at 1500—2000°C, converted into graphite [7782-42-5]. In 1880, the British scientist Haimay reported (1) that he made diamond from hydrocarbons, bone oil, and lithium, but no one has been able to repeat this feat (2). About the same time, Moissan beheved (3) that he made diamond from hot molten mixtures of iron and carbon, but his experiments could not be repeated (4,5). 

In the attempt at diamond synthesis (4), much unsuccesshil effort was devoted to processes that deposited carbon at low, graphite-stable pressures. Many chemical reactions Hberating free carbon were studied at pressures then available. New high pressure apparatus was painstakingly buHt, tested, analy2ed, rebuilt, and sometimes discarded. It was generally beheved that diamond would be more likely to form at thermodynamically stable pressures. 

Crystal Morphology. Size, shape, color, and impurities are dependent on the conditions of synthesis (14—17). Lower temperatures favor dark colored, less pure crystals higher temperatures promote paler, purer crystals. Low pressures (5 GPa) and temperatures favor the development of cube faces, whereas higher pressures and temperatures produce octahedral faces. Nucleation and growth rates increase rapidly as the process pressure is raised above the diamond—graphite equiUbrium pressure. 

Shock Synthesis. When graphite is strongly compressed and heated by the shock produced by an explosive charge, some (up to 10%) diamond may form (26,27). These crystaUite diamonds are small (on the order of 1 llm) and appear as a black powder. The peak pressures and temperatures, which are maintained for a few microseconds, are estimated to be about 30 GPa (300 kbar) and 1000 K. It is beheved that the diamonds found in certain meteorites were produced by similar shock compression processes that occurred upon impact (5). 

Static Pressure Synthesis. Diamond can form direcdy from graphite at pressures of about 13 GPa (130 kbar) and higher at temperatures of about 3300—4300 K (7). No catalyst is needed. The transformation is carried out in a static high pressure apparatus in which the sample is heated by the discharge current from a capacitor. Diamond forms in a few milliseconds and is recovered in the form of polycrystalline lumps. From this work, and studies of graphite vaporization/melting, the triple point of diamond, graphite, and molten carbon is estimated to He at 13 GPa and 5000 K (Fig. 1)... 

Graphite fluoride continues to be of interest as a high temperature lubricant (6). Careful temperature control at 627 3° C results in the synthesis of poly(carbon monofluoride) [25136-85-0] (6). The compound remains stable in air to ca 600°C and is a superior lubricant under extreme conditions of high temperatures, heavy loads, and oxidising conditions (see Lubrication and lubricants). It can be used as an anode for high energy batteries (qv). 

Chapter 1 contains a review of carbon materials, and emphasizes the stmeture and chemical bonding in the various forms of carbon, including the foui" allotropes diamond, graphite, carbynes, and the fullerenes. In addition, amorphous carbon and diamond fihns, carbon nanoparticles, and engineered carbons are discussed. The most recently discovered allotrope of carbon, i.e., the fullerenes, along with carbon nanotubes, are more fully discussed in Chapter 2, where their structure-property relations are reviewed in the context of advanced technologies for carbon based materials. The synthesis, structure, and properties of the fullerenes and... 

Graphite was tised as substrate for the deposition of carbon vapor. Prior to the tube and cone studies, this substrate was studied by us carefully by STM because it may exhibit anomalotis behavior w ith unusual periodic surface structures[9,10]. In particular, the cluster-substrate interaction w as investigated IJ. At low submonolayer coverages, small clusters and islands are observed. These tend to have linear struc-tures[12j. Much higher coverages are required for the synthesis of nanotubes and nanocones. In addition, the carbon vapor has to be very hot, typically >3000°C. We note that the production of nanotubes by arc discharge occurs also at an intense heat (of the plasma in the arc) of >3000°C. 

The direct linking of carbon nanotubes to graphite and the continuity in synthesis, structure and properties between carbon nanotubes and vapor grown carbon fibers is reviewed by the present leaders of this area, Professor M. Endo, H. Kroto, and co-workers. Further insight into the growth mechanism is presented in the article by Colbert and Smalley. New synthesis methods leading to enhanced production... 

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