Plasma synthesis of hexagonal-pyramidal graphite hillocks

Glad, X.; Poucques, Ludovic de; Jaszczak, John A.; Belmahi, M.; Ghanbaja, Jaâfar; Bougdira, J.

doi:10.1016/j.carbon.2014.04.084

Cited by 13 publications

(19 citation statements)

References 37 publications

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“…5,8,9). To a certain extent, similar microstructures have been described in Glad et al (2014), wherein the microstructures were observed on the surface of synthesized graphite produced from gas phase This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change.…”

Section: Discussionmentioning

confidence: 71%

Graphite paradox in Baikal geyserite paleovalley, Russia

Шумилова

Danilova

Mayer

et al. 2021

American Mineralogist

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Natural graphite, a polygenic mineral, is a product of regional, contact, impact metamorphism, and magmatic or fluid deposition. In fluid-deposited graphite, aqueous C-O-H systems play a special role in determining the characteristics of hydrothermal products by shifting the chemical equilibrium. From this viewpoint, the recently discovered carboniferous mineralization in the Baikal hydrothermalites has attracted increasing interest with regard to graphite crystallization under the influence of low-pressure low-temperature (LPLT) carboniferous H2O-rich fluids. Herein, we studied graphite mineralization in the geyserites and travertines of the Baikal geyserite paleovalley (Eastern Siberia, Russia) by applying a multitude of mineralogical studies. Optical, scanning, transmission electron, and atomic force microscopy, energy-dispersive spectroscopy, Raman spectroscopy, and carbon isotopic composition analyses of graphite, carbonate carbon, and oxygen in both the hydrothermalites and host rocks were conducted. The obtained results revealed several peculiar features regarding the graphite in geyserites and travertines. We found that Baikal graphite, earlier predicted to be a product of hydrothermalites, generally occurs as a relict graphite of the host metamorphic rocks with partial in situ redeposition. The newly formed LPLT fluid-deposited graphite is characterized by micrometer- and submicrometer-sized idiomorphic crystallites overgrown on the relict metamorphic graphite seeds and between calcite sinter zones during the last stage of travertine formation. The results present additional valuable data for understanding the mechanism, range of the formation conditions, and typomorphism of fluid-deposited graphite with probable crystallization from carbon solution in the C-O-H system at LPLT conditions.

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Section: Discussionmentioning

confidence: 71%

Graphite paradox in Baikal geyserite paleovalley, Russia

Шумилова

Danilova

Mayer

et al. 2021

American Mineralogist

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“…The conductive SS substrate is used for scanning electron microscopy (SEM, JEOL JSM6700F at 3 kV), while the Ni grid allows for transmission electron microscopy (TEM, JEOL JEM-2100F at 200 kV). Under a 200-kV beam, electrons transfer up to 43 eV to the graphite lattice 19 , which is greater than its threshold displacement energy 43 , 44 . Incident electrons thus lead to the formation of numerous Frenkel pairs.…”

Section: Methodsmentioning

confidence: 98%

Synthesis of core–shell copper–graphite submicronic particles and carbon nano-onions by spark discharges in liquid hydrocarbons

Glad

Gorry

Suk

et al. 2021

Sci Rep

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Spark discharge in hydrocarbon liquids is considered a promising method for the synthesis of various nanomaterials, including nanocomposites. In this study, copper–carbon particles were synthesized by generating spark discharges between two Cu electrodes immersed in heptane, cyclohexane, or toluene. The synthesized particles were characterized using scanning electron microscopy, high-resolution transmission electron microscopy, and selected area electron diffraction. Overall, two families of particles were observed: Cu particles (diameter < 10 nm) embedded in a carbon matrix and submicrometric Cu particles encapsulated in a carbon shell. The obtained results indicate that the size distribution of the Cu nanoparticles and the degree of graphitization of the carbon matrix depend on the liquid. Indeed, discharges in heptane lead to Cu particles with diameters of 2–6 nm embedded in a carbon matrix of low graphitization degree, while discharges in toluene result in particles with diameters of 2–14 nm embedded in carbon matrix of high graphitization degree. Based on the obtained experimental results, it is proposed that the Cu nanoparticles are produced in the plasma core where Cu (evaporated from the electrode surface) and carbonaceous species (decomposition of the liquid) are present. When the plasma hits the electrode surface, hot (thousands of Kelvin) Cu particles are ejected from the electrode, and they propagate in the liquid. The propagation of the hot particles in the liquid results in the local evaporation of this liquid, which leads to the formation of a C-shell around each Cu particle. In few cases where the shape of the Cu particle is not spherical, carbon nanoonions are detected between the C-shell and the Cu core. These nanoonions are supposedly formed under the effect of the fluid vortices generated close to the particle surfaces when these latter are ejected into the liquid.

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“…The experimental set-up is described in details in our previous papers 16,[18][19][20] . To summarize, the GHPs are synthesized from two different graphite substrates: FG and HOPG (table 1).…”

Section: A-experimental Set-upmentioning

confidence: 99%

“…Recently, graphite hexagonal pyramids (GHPs, a new type of graphite crystals) have been synthesized on flexible graphite (FG, figure 1(a,b)) and highly-ordered pyrolytic graphite (HOPG) substrates 16 . We suggested a formation mechanism by a plasma etching process.…”

Section: Introduction-mentioning

confidence: 99%