Deposition mechanism of pyrolytic carbons at temperature between 800–1200 °C

Shi, Rong; Li, H.J.; Zheng, Yang; Mokuang, Kang

doi:10.1016/s0008-6223(97)00140-1

Cited by 36 publications

(11 citation statements)

References 5 publications

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“…This suggests that the nature of the hydrocarbon is not fundamental to the formation of hexagonal diamond as the liquid only acts to provide carbon. It is well known that pyrolytic carbon can be synthesized by heating hydrocarbons to 700-1200 o C [15,18,19] but pyrolysis is unlikely in our experiments because the interaction between fs pulses and molecules is a non-thermal process [10]. It appears that the dominant mechanism in fs irradiation is multiphoton ionization which causes step-wise dissociation of the hydrocarbon precursor molecules.…”

Section: Discussionmentioning

confidence: 78%

Synthesis of Nanocrystalline Hexagonal Diamond Films in Organic Solvents by Femtosecond Laser Irradiation

Duley

2007

MRS Proc.

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Nanocrystalline diamond films have been synthesized on various substrates by 800 nm fs laser irradiation of a variety of organic solvents including acetone, pentane, hexane, heptane, octane, dodecane, and hexadecane in the presence of a transition metal catalyst. 632 nm Raman spectra display a strong vibration mode at 1308 cm -1 characteristic of hexagonal diamond. X-ray photoelectron spectra confirm that the film is mainly sp 3 -bonded carbon containing a low concentration of sp 2 -bonded inclusions. Film microstructure shows that these films are assembled from nanoparticles having an average size of < 100 nm. Analysis of the liquid after irradiation using HPLC techniques indicates that polyyne molecules are also synthesized during irradiation. It is possible that these species are formed as the products of ion chemistry following Coulomb explosion. This process may enable a new method for the creation of nanocrystalline hexagonal diamond layers for micro-electronic and other applications.

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Section: Discussionmentioning

confidence: 78%

Synthesis of Nanocrystalline Hexagonal Diamond Films in Organic Solvents by Femtosecond Laser Irradiation

Duley

2007

MRS Proc.

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“…Most of the studies of carbon deposition indicate formation of elemental carbon in the reforming reactions as the main source of carbon deposition, however, without supplying a validated mechanism. Two models were considered for pyrolytic carbon (Zheng et al 2013): a deposition droplet model proposed by Shi et al (1997) and the combined mechanism of nucleation on graphene and of carbon growth at the edge of graphene (Hu and Hüttinger 2002). Several carbon containing intermediate species were detected during methane decomposition at catalyst surfaces, and associated mechanisms of filamentous deposit growth were proposed , Snoeck et al 1997a, Wagg et al 2005.…”

Section: Carbon Depositsmentioning

confidence: 99%

On thermodynamic equilibrium of carbon deposition from gaseous C-H-O mixtures: updating for nanotubes

Jaworski

Zakrzewska

Pianko‐Oprych

2017

Reviews in Chemical Engineering

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AbstractExtensive literature information on experimental thermodynamic data and theoretical analysis for depositing carbon in various crystallographic forms is examined, and a new three-phase diagram for carbon is proposed. The published methods of quantitative description of gas-solid carbon equilibrium conditions are critically evaluated for filamentous carbon. The standard chemical potential values are accepted only for purified single-walled and multi-walled carbon nanotubes (CNT). Series of C-H-O ternary diagrams are constructed with plots of boundary lines for carbon deposition either as graphite or nanotubes. The lines are computed for nine temperature levels from 200°C to 1000°C and for the total pressure of 1 bar and 10 bar. The diagram for graphite and 1 bar fully conforms to that in (Sasaki K, Teraoka Y. Equilibria in fuel cell gases II. The C-H-O ternary diagrams. J Electrochem Soc 2003b, 150: A885–A888). Allowing for CNTs in carbon deposition leads to significant lowering of the critical carbon content in the reformates in temperatures from 500°C upward with maximum shifting up the deposition boundary O/C values by about 17% and 28%, respectively, at 1 and 10 bar.

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“…During the corresponding transport time, the temperature of the samples decreases, and the surface free energy of the filaments is changed as the temperature decreases. [33][34][35][36] The latter results in the second nucleation process of the pyrolytic carbon deposition. The pyrolytic carbon deposition periodically nucleates to form biconical deposit morphologies, as shown in Figure 5b.…”

Section: Resultsmentioning

confidence: 99%

A Carbon Nanofilament-Bead Necklace

Holleitner

Qian

et al. 2008

J. Phys. Chem. C

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Carbon nanofilaments with carbon beads grown on their surfaces were successfully synthesized reproducibly by a floating catalyst CVD method. The nanofilaments hosting the pearl-like structures typically show an average diameter of about 60 nm, which mostly consists of low-ordered graphite layers. The beads with diameter range 150-450 nm are composed of hundreds of crumpled and random graphite layers. The mechanism for the formation of these beaded nanofilaments is ascribed to two nucleation processes of the pyrolytic carbon deposition, arising from a temperature gradient between different parts of the reaction chamber. Furthermore, the Raman scattering properties of the beaded nanofilaments have been measured, as well as their confocal Raman G-line images. The Raman spectra reveal that that the trunks of the nanofilaments have better graphitic properties than the beads, which is consistent with the HRTEM analysis. The beaded nanofilaments are expected to have high potential applications in composites, which should exhibit both particleand fiber-reinforcing functions for the host matrixes.

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Deposition mechanism of pyrolytic carbons at temperature between 800–1200 °C

Cited by 36 publications

References 5 publications

Synthesis of Nanocrystalline Hexagonal Diamond Films in Organic Solvents by Femtosecond Laser Irradiation

Synthesis of Nanocrystalline Hexagonal Diamond Films in Organic Solvents by Femtosecond Laser Irradiation

On thermodynamic equilibrium of carbon deposition from gaseous C-H-O mixtures: updating for nanotubes

A Carbon Nanofilament-Bead Necklace

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