Carbon structures in silicon carbide derived carbon

Welz, Sascha; McNallan, Michael J.; Gogotsi, Yury

doi:10.1016/j.jmatprotec.2006.03.103

Cited by 95 publications

(61 citation statements)

References 38 publications

(57 reference statements)

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“…The process is similar to shock-formation conditions in a cosmic-impact event, during which lonsdaleite typically forms from the high-pressure transformation of graphite. However, synthetic lonsdaleite can also be produced under nonshock conditions, e.g., by growth in a hydrogen plasma jet in a CVDlike process (Maruyama et al 1992) and by enhancement of carbon in silicon carbide wafers (Gogotsi et al 2001;Welz et al 2006;table D5). These other processes suggest that lonsdaleite could form without physical shock at high temperatures in the fireball of a cosmic-impact event.…”

Section: Potential Origin From Volcanism or In The Mantlementioning

confidence: 99%

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Kinzie¹,

Hee

Stich

et al. 2014

The Journal of Geology

170

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. A B S T R A C TA major cosmic-impact event has been proposed at the onset of the Younger Dryas (YD) cooling episode at ≈12,800 ‫ע‬ 150 years before present, forming the YD Boundary (YDB) layer, distributed over 150 million km 2 on four continents. In 24 dated stratigraphic sections in 10 countries of the Northern Hemisphere, the YDB layer contains a clearly defined abundance peak in nanodiamonds (NDs), a major cosmic-impact proxy. Observed ND polytypes include cubic diamonds, lonsdaleite-like crystals, and diamond-like carbon nanoparticles, called n-diamond and i-carbon. The ND abundances in bulk YDB sediments ranged up to ≈500 ppb (mean: 200 ppb) and that in carbon spherules up to ≈3700 ppb (mean: ≈750 ppb); 138 of 205 sediment samples (67%) contained no detectable NDs. Isotopic evidence indicates that YDB NDs were produced from terrestrial carbon, as with other impact diamonds, and were not derived from the impactor itself. The YDB layer is also marked by abundance peaks in other impact-related proxies, including cosmic-impact spherules, carbon spherules (some containing NDs), iridium, osmium, platinum, charcoal, aciniform carbon (soot), and high-temperature melt-glass. This contribution reviews the debate about the presence, abundance, and origin of the concentration peak in YDB NDs. We describe an updated protocol for the extraction and concentration of NDs from sediment, carbon spherules, and ice, and we describe the basis for identification and classification of YDB ND polytypes, using nine analytical approaches. The large body of evidence now obtained about YDB NDs is strongly consistent with an origin by cosmic impact at ≈12,800 cal BP and is inconsistent with formation of YDB NDs by natural terrestrial processes, including wildfires, anthropogenesis, and/or influx of cosmic dust.

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Section: Potential Origin From Volcanism or In The Mantlementioning

confidence: 99%

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Kinzie¹,

Hee

Stich

et al. 2014

The Journal of Geology

170

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“…Carbon-based materials, and CDCs in particular, present a unique challenge for these forcefields because of their nanoscale heterogeneity. Individual forcefields can sufficiently describe specific structural moeities, such as short-range graphitization at low density [67], but are often not sufficient to capture the full range of non-ideal features observed in CDCs [68].…”

Section: Introductionmentioning

confidence: 99%

An Atomistic Carbide-Derived Carbon Model Generated Using ReaxFF-Based Quenched Molecular Dynamics

Thompson

Dyatkin

Wang

et al. 2017

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Abstract:We report a novel atomistic model of carbide-derived carbons (CDCs), which are nanoporous carbons with high specific surface areas, synthesis-dependent degrees of graphitization, and well-ordered, tunable porosities. These properties make CDCs viable substrates in several energy-relevant applications, such as gas storage media, electrochemical capacitors, and catalytic supports. These materials are heterogenous, non-ideal structures and include several important parameters that govern their performance. Therefore, a realistic model of the CDC structure is needed in order to study these systems and their nanoscale and macroscale properties with molecular simulation. We report the use of the ReaxFF reactive force field in a quenched molecular dynamics routine to generate atomistic CDC models. The pair distribution function, pore size distribution, and adsorptive properties of this model are reported and corroborated with experimental data. Simulations demonstrate that compressing the system after quenching changes the pore size distribution to better match the experimental target. Ring size distributions of this model demonstrate the prevalence of non-hexagonal carbon rings in CDCs. These effects may contrast the properties of CDCs against those of activated carbons with similar pore size distributions and explain higher energy densities of CDC-based supercapacitors.

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“…The carbon layer consists of various carbon composite structures, depending on the synthesis parameters such as the gas composition, reaction temperature, and reaction time. 4) Figure 1 shows a schematic diagramming the CDC reactor used to grow the carbon films. CDC synthesis was performed at atmospheric pressure, and Ar, Cl 2 , and H 2 were supplied as the carrier, chlorination, and treatment gases, respectively.…”

Section: Carbide Derived Carbon Synthesis: Growthmentioning

confidence: 99%

“…Carbide-derived carbon (CDC) synthesis is a method of growing carbon composite layers on carbide materials such as TiC and SiC. CDC layers have recently been produced by selectively etching metal components in carbide materials such as SiC, 4) TiC, 5) Ti 3 SiC 2 , 6) B 4 C, 7) ZrC, 8) MoC, 9) NbC, 10) VC, 11) and WC. 12) CDC layers may consist of amorphous carbon, crystalline graphite, nanocrystalline diamond, and carbon sheets (i.e., graphene), depending on the synthesis conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Hence, the carbon structures of CDC layers synthesized above 1000°C are mostly graphite-like (i.e., they contain mostly sp 2 -hybridized carbon atoms), and the interface between the CDC layers and the metal carbide usually consists of diamond-like carbon structures. 4) The synthesis temperature clearly significantly affects the CDC carbon structures; however, other synthesis parameters also affect Chun et al: Carbide derived carbon: from growth to tribological application them and should be considered for any CDC application. Thus, the following section discusses the effects of various synthesis parameters on CDC carbon structures and related tribological properties.…”

mentioning

confidence: 99%

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Carbide derived carbon: from growth to tribological application

Chun

Lim

2014

J. Ceram. Soc. Japan

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We reviewed the current research on carbide-derived carbon (CDC) for tribological applications. Carbon materials have been produced using CDC synthesis, in which the metallic components of carbides are selectively etched using high-temperature chlorination. The CDC materials show superior material properties for various applications. SiC is the most widely used carbide, so it was the main focus of the discussion. CDC films show various synthesis-parameter-dependent crystal structures, which affect the mechanical and electrical properties. We discussed the effects of CDC synthesis parameters including adding hydrogen, choosing an appropriate reaction temperature, using catalysts, and modifying the substrate surface with a gradient carbon layer on the structures and tribological properties of CDC layers. The reactions between chlorine gas and the metal components of carbides require the proper reaction temperature because the bonding strengths of carbide materials are unique. CDCsynthesized carbon materials show excellent mechanical and physical properties, which can be continuously enhanced by innovatively modifying various synthesis parameters and by combining CDC materials with other materials. Therefore, CDC materials show great potential for being used in a broader range of applications, and they may lead to new and extended applications for ceramic materials.

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Carbon structures in silicon carbide derived carbon

Cited by 95 publications

References 38 publications

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

An Atomistic Carbide-Derived Carbon Model Generated Using ReaxFF-Based Quenched Molecular Dynamics

Carbide derived carbon: from growth to tribological application

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