Low temperature pyrocarbons: a review

Bourrat, Xavier; Langlais, F.; Chollon, Georges; Vignoles, Gérard L.

doi:10.1590/s0103-50532006000600005

Cited by 46 publications

(39 citation statements)

References 12 publications

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“…When processing hydrocarbons (varying pressure, P, and temperature, T, in the reactor), gas phase nucleation leads to soots, whereas heterogeneous nucleation on the substrate leads to the formation of pyrocarbons, which can contain up to 5 at. % of hydrogen [252]. The Raman spectroscopy of soots (e.g., diesel soots, spark discharge soots, commercial black carbons) has been investigated in detail in 2005 [122].…”

Section: Very Defective Carbons: Pyrocarbons Coals and Sootsmentioning

confidence: 99%

“…High resolution TEM shows Pyrocarbons are generally deposited on substrates by cracking hydrocarbons at temperatures higher than 900 • C, using chemical vapor deposition processes. Using infiltration process, pyrocarbons are used mainly in carbon/carbon fiber composites, whose aim is to withstand mechanical stress at high temperature [252]. A large variety of pyrocarbon textures exist.…”

Section: Very Defective Carbons: Pyrocarbons Coals and Sootsmentioning

confidence: 99%

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A Guide to and Review of the Use of Multiwavelength Raman Spectroscopy for Characterizing Defective Aromatic Carbon Solids: from Graphene to Amorphous Carbons

2017

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sp 2 hybridized carbons constitute a broad class of solid phases composed primarily of elemental carbon and can be either synthetic or naturally occurring. Some examples are graphite, chars, soot, graphene, carbon nanotubes, pyrolytic carbon, and diamond-like carbon. They vary from highly ordered to completely disordered solids and detailed knowledge of their internal structure and composition is of utmost importance for the scientific and engineering communities working with these materials. Multiwavelength Raman spectroscopy has proven to be a very powerful and non-destructive tool for the characterization of carbons containing both aromatic domains and defects and has been widely used since the 1980s. Depending on the material studied, some specific spectroscopic parameters (e.g., band position, full width at half maximum, relative intensity ratio between two bands) are used to characterize defects. This paper is addressed first to (but not limited to) the newcomer in the field, who needs to be guided due to the vast literature on the subject, in order to understand the physics at play when dealing with Raman spectroscopy of graphene-based solids. We also give historical aspects on the development of the Raman spectroscopy technique and on its application to sp 2 hybridized carbons, which are generally not presented in the literature. We review the way Raman spectroscopy is used for sp 2 based carbon samples containing defects. As graphene is the building block for all these materials, we try to bridge these two worlds by also reviewing the use of Raman spectroscopy in the characterization of graphene and nanographenes (e.g., nanotubes, nanoribbons, nanocones, bombarded graphene). Counterintuitively, because of the Dirac cones in the electronic structure of graphene, Raman spectra are driven by electronic properties: Phonons and electrons being coupled by the double resonance mechanism. This justifies the use of multiwavelength Raman spectroscopy to better characterize these materials. We conclude with the possible influence of both phonon confinement and curvature of aromatic planes on the shape of Raman spectra, and discuss samples to be studied in the future with some complementary technique (e.g., high resolution transmission electron microscopy) in order to disentangle the influence of structure and defects.

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Section: Very Defective Carbons: Pyrocarbons Coals and Sootsmentioning

confidence: 99%

Section: Very Defective Carbons: Pyrocarbons Coals and Sootsmentioning

confidence: 99%

A Guide to and Review of the Use of Multiwavelength Raman Spectroscopy for Characterizing Defective Aromatic Carbon Solids: from Graphene to Amorphous Carbons

2017

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“…A snapshot of a carbon sheet taken from a model of a rough laminar pyrolytic carbon 19 , reconstructed with this method, is shown Figure 1a. As can be seen, the sheet is made of disoriented purely hexagonal domains (light grey) bound together by defective planar In what follows, we report on the structure and properties of different nano-sheets and tubes based on this pattern as obtained from density functional theory (DFT) and force field calculations.…”

Section: Introductionmentioning

confidence: 99%

Rippled nanocarbons from periodic arrangements of reordered bivacancies in graphene or nanotubes

Leyssale

Vignoles

Villesuzanne

2012

The Journal of Chemical Physics

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We report on various nanocarbons formed from a unique structural pattern containing two pentagons, three hexagons and two heptagons, resulting from local rearrangements around a divacancy in pristine graphene or nanotubes. This defect can be inserted in sheets or tubes either individually or as extended defect lines. Sheets or tubes containing only this defect as a pattern can also be obtained. These fully defective sheets, and most of the tubes, present a very pronounced rippled (wavy) structure and their energies are lower than other structures based on pentagons and heptagons published so far. Another particularity of these rippled carbon sheets is their ability to fold themselves into a two-dimensional porous network of interconnected tubes upon heat treatment as shown by hybrid Monte Carlo simulations.Finally, contrary to the common belief that pentagon/heptagon based structures are metallic, this work shows that this defect pattern should give rise to semi-metallic conduction.

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“…It is therefore quite unavailable in bulk form. It has, depending on its processing parameters, a very versatile nanostructure [3][4][5] and consequently, broadly varying mechanical and thermal properties, usually anisotropic to a more or less large extent 6 . Posterior heat treatments may further alter their structure and properties 7 .…”

Section: Introductionmentioning

confidence: 99%

Thermal properties measurements of a silica/pyrocarbon composite at the microscale

Battaglia

Vignoles

2016

Journal of Applied Physics

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Laminar pyrocarbons are used as interphases or matrices of carbon/carbon and ceramic-matrix composites in several high-temperature aerospace applications. Depending on their organization at the microscale, they can have a variety of mechanical and thermal properties. Hence, it is important to know, before thermal processing, the properties of these matrices at the micrometer scale in order to improve and control the composite behavior in a macroscopic scale. We use Scanning Thermal Microscopy (SThM) on a silica fiber / regenerative laminar pyrocarbon matrix composite to provide an insight into the effective thermal conductivity of pyrocarbon as well as the thermal contact resistance at the interface between fiber and matrix. The conductivity of pyrocarbon is discussed as a function of its nanostructural organization.

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Low temperature pyrocarbons: a review

Cited by 46 publications

References 12 publications

A Guide to and Review of the Use of Multiwavelength Raman Spectroscopy for Characterizing Defective Aromatic Carbon Solids: from Graphene to Amorphous Carbons

A Guide to and Review of the Use of Multiwavelength Raman Spectroscopy for Characterizing Defective Aromatic Carbon Solids: from Graphene to Amorphous Carbons

Rippled nanocarbons from periodic arrangements of reordered bivacancies in graphene or nanotubes

Thermal properties measurements of a silica/pyrocarbon composite at the microscale

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