Structures carbon nitrides

The research work on carbon nitride materials was first motivated due to its hypothetical super-hardness. The tribological properties of the CNx films are, of course, the emphasis of the succeeding research works. Although the expected structure and hardness have not been achieved up to the present, the potential interesting properties still stimulate many approaches on the tribological behavior of CNx films. Figure 8 gives the results of hardness measurement reported by the... 

McCuUoch, D. G. and Merchant, A. R., The Effect of Annealing on the Structure of Cathodic Arc Deposited Amorphous Carbon Nitride Films, Thin Solid Films, Vol. 290, 1996, pp. 99-102. 

Czyzniewski, A., Precht, W., Pancielejko, M., Myslinski, P., and Walkowiak, W., Structure, Composition and Tribological Properties of Carbon Nitride Films," Thin Solid Films, Vol. 317, No. 1-2,1998, pp. 384-387. 

The work on carbon nitride solids is strongly related to research on diamondlike carbon (DLC) materials [5, 6]. DLC materials are thin film amorphous metastable carbon-based solids, pure or alloyed with hydrogen, which have properties similar to that of crystalline diamond (high hardness, low friction coefficient, high resistance to wear and chemical attack). This resemblance to diamond is due to the DLC structure, which is characterized by a high fraction of highly cross-linked sp -hybridized carbon atoms. To obtain this diamond-like structure... 

Research on plasma-deposited a-C(N) H films has been frequently included in the general discussion of carbon nitride solids [2, 3]. However, the presence of hydrogen in its composition, and the complexity of the deposition process, which introduces the nitrogen species in the already intricate hydrocarbon plasma-deposition mechanism, make a-C(N) H films deserve special consideration. This is the aim of the present work to review and to discuss the main results on the growth, structure, and properties of plasma-deposited a-C(N) H films. As this subject is closely related to a-C H films, a summary of the main aspects relative to the plasma deposition of a-C H films, their structure, and the relationship between the main process parameters governing film structure and properties is presented... 

A. Y. Liu and M. L. Cohen, Structural Properties and Electronic Structure of Low-Compressibility Materials P-silicon Nitride and Hypothetical Carbon Nitride (P-C3N4), Phys. Rev. B, 41(15), 10727-34 (1990). 

Carbon nitride, 27 214—215 conductivity of, 2 7 204-206 field emission properties of, 27 221 theoretical band structure calculations for, 27 203-204 Carbon nitride films, 2 7 205 Carbon nitride solids, 2 7 203 Carbonochloridic esters, 6 290 Carbon paper, 4 738-739 Carbon profile, in gas carburizing, 26 204 Carbon Raschig-ring tower packing, 22 745 Carbon reduction, of ferrovanadium, 25 518... 

The arrangement of carbon atoms in one plane of the graphite structure. Boron nitride can also form this structure (hexagonal BN) with atoms of B and N alternating as indicated by shaded and open circles. 

Figue 4. Different possible structures for hypothetical carbon nitrides [17]. (P-C3N4, P i or a-C3N4, Pi c ... 

Ravindran TR, Badding JV (2006) UV Raman studies on carbon nitride structures. J Mater Sci 41 7145... 

C MAS-NMR spectroscopy was used to quantify the different carbon species in synthetically produced nanodiamonds.430 A 13C study has been reported to study the modification of the electronic properties of SWCNT by alkali intercalation.431,432 13C MAS-NMR data were used to study the structure of 13C-enriched SWCNT, prepared by catalytic decomposition of CH4.433 H, 13C and 15N MAS-NMR spectra of amorphous carbon nitride (a-CNx) films were consistent with sp2 hybridised nitrogen atoms in an aromatic carbon... 

Formula C2N2 MW 52.04 CAS [460-19-5] Structure N=C—C=N Synonyms ethanedinitrile oxalic acid dinitrile oxalonitrile oxalyl cyanide carbon nitride dicyan... 

This chapter examines some potential structures that have been proposed for different phases of carbon-nitride and also the tertiary material silicon-carbon-nitride. First we briefly examine some basic modeling procedures that have been employed to date when investigating these materials and then discuss properties of the predicted structures. 

There is understandably some pessimism regarding a commercial synthesis of superhard carbon nitride especially in view of the intense effort that has been put into its synthesis by many laboratories in the last few years with no firm result to date. Yet the wisdom of the computational arguments upon which the various structures of the material have been predicted seems firm and they have been shown to be capable of giving us valuable insight in many other areas of materials science. Experiences gained regarding the commercial synthesis of diamond and cubic BN could probably lead ways that carbon nitride can be synthesized, yet other more novel routes also cannot be excluded. 

Figure 9. Theoretically suggested crystal structures of carbon nitride C3N4 (filled circles represent the carbon atoms) (a) Hexagonal structure corresponding to that of /3Si3N4 or phenacite, Be2Si04. (b) Cubic structure corresponding to that of willemite-II, the high-pressure phase of Zn2Si04 (I3J. First published in [152] and reproduced with permission.

Plasma decomposition of CH4 and N2 provided amorphous solids containing C, N, and H, exclusively [87], High pressure pyrolysis of tetracyanoethylene, (CN)2C=C(CN)2, gave C466N with graphitic structure [88]. Similarly, the gas phase decomposition of pyridine in the presence of chlorine at 800°C provided the carbon nitride C5N with a hexagonal sheet structure [89]. 

Martin-Gil et al. reported on the synthesis of cubic carbon nitride with the zinc blende structure by pyrolysis of N,N-diethyl-l,4-phenylene-diammonium sulphate at 800°C in an N2 atmosphere using Se02 as a catalyst [90]. The material obtained contained both an amorphous matrix and polycrystalline regions with crystallites of 5-50 nm in size. The sample as whole had a composition with 0.2 estimated using EELS (electron energy loss spectroscopy) data to be C N, with x and y between 3 and 4. The... 

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