scholarly journals Mixed metamorphic and fluid graphite deposition in Palaeoproterozoic supracrustal rocks of the Lewisian Complex, NW Scotland

Terra Nova ◽  
2021 ◽  
Author(s):  
John Parnell ◽  
Connor Brolly ◽  
Adrian Boyce
Keyword(s):  
Graphite Deposition

Balance of graphite deposition and multishell carbon nanotube growth in the carbon arc discharge

1997 ◽  
Vol 12 (1) ◽  
pp. 244-252 ◽  
Author(s):  
P. M. Ajayan ◽  
Ph. Redlich ◽  
M. Rühle
Keyword(s):  
Carbon Nanotube ◽  
Large Scale ◽  
Arc Discharge ◽  
Precise Understanding ◽  
Atomistic Models ◽  
Graphite Deposition ◽  
Carbon Arc ◽  
Carbon Nanotube Growth ◽  
Nanotube Growth ◽  
Continuous Deposition

Except for atomistic models of individual carbon nanotube growth, there is still no precise understanding of the large scale deposition of carbon during the arc discharge. We study the microstructure of cathode deposits in detail using scanning electron microscopy, focusing on two distinct regimes found in the deposits having different large scale morphology. The shell grown circumferentially consists of extended graphite layers with preferred orientation, and the structure reveals close similarity to pyrolitic graphite. The core region is a porous assembly of nanotubes and nanoparticles. We conclude that closed nanostructures self-assemble from a dense carbon vapor, whereas pyrographitic shell grows by continuous deposition on exposed substrates.

scholarly journals PHYSICO-CHEMICAL BASES OF ELECTROLYTIC SYNTHESIS OF CARBON NANOMATERIALS FROM MOLTEN SALTS. Part 1

2019 ◽  
Vol 85 (2) ◽  
pp. 69-79
Author(s):  
Inessa Novoselova ◽  
Serhii Kuleshov
Keyword(s):  
Solid Solution ◽  
Alkali Metal ◽  
High Speed ◽  
Carbon Nanomaterials ◽  
Carbon Deposition ◽  
Carbide Phases ◽  
Physico Chemical ◽  
Graphite Deposition ◽  
Predominant Process ◽  
Oxide Ions

An analysis of the decomposition potentials of lithium, sodium, potassium, calcium, barium, and magnesium carbonates with different versions of cathode products (elemental carbon, carbon monoxide, metal and carbide) in the range of 300-1900 K showed that for K2CO3 deposition of alkali metal on the cathode is most energetically profitable process at all temperatures. For Na2CO3 it is possible to obtain carbon at T < 1000 K. With temperature increase, the predominant process is the reduction of alkali metal. For Li2CO3, CaCO3, BaCO3, MgCO3 at T < 950 °C carbon deposition will be more advantageous, at higher temperatures reduction up to CO will be more advantageous. The decomposition of CO2 flows at more positive potentials compared with carbonate systems. However, low activity of CO2 in carbonate-containing melts will prevent the significant contribution of this reaction to the electrode process. Thermodynamic calculations of the dependence of the carbon deposition potentials from carbonate anion on the acidity of the melt (concentration of oxide ions) show the possibility of displacing this potential up to 0.8 V by changing the acid-base properties of the melt. On the basis of the analysis of binary phase diagrams, Me–C and MeC–C, criteria for selecting the cathode material for generation of the tubular structure of graphite are established. The diagrams should contain: (1) – solid solutions of C–Me at a temperature of 700–900 °C and sufficient solubility of carbon (up to ~ 1 at.%) in the metal should be observed; (2) – after saturation of the solid solution with carbon, the precipitation (precipitation) of graphite from the metal should occur without the formation of intermediate carbide phases; (3) – in the case of the formation of carbides, the diffusion of carbon in the solid solution С–Ме and in the carbide phase MeС should flow with high speed and quickly reach the concentration of carbon saturation for graphite deposition.

Detecting hydrothermal graphite deposition during metamorphism and gold mineralization

2005 ◽  
Vol 162 (3) ◽  
pp. 429-432 ◽  
Author(s):  
Iain K. Pitcairn ◽  
Steve Roberts ◽  
Damon A. H. Teagle ◽  
Dave Craw
Keyword(s):  
Gold Mineralization ◽  
Graphite Deposition

scholarly journals Key factors controlling massive graphite deposition in volcanic settings: an example of a self-organized critical system

2012 ◽  
Vol 169 (3) ◽  
pp. 269-277 ◽  
Author(s):  
F. J. Luque ◽  
L. Ortega ◽  
J. F. Barrenechea ◽  
J.-M. Huizenga ◽  
D. Millward
Keyword(s):  
Key Factors ◽  
Critical System ◽  
Self Organized ◽  
Graphite Deposition

scholarly journals Nanostructured Diamond-Like Carbon Films Grown by Off-Axis Pulsed Laser Deposition

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Seong Shan Yap ◽  
Chen Hon Nee ◽  
Seong Ling Yap ◽  
Teck Yong Tou
Keyword(s):  
Pyrolytic Graphite ◽  
Pulsed Laser ◽  
Maximum Size ◽  
Carbon Films ◽  
Diamond Like Carbon ◽  
Oblique Angle Deposition ◽  
Ion Energy ◽  
Graphite Deposition ◽  
Axis Position ◽  
Effective Angle

Nanostructured diamond-like carbon (DLC) films instead of the ultrasmooth film were obtained by pulsed laser ablation of pyrolytic graphite. Deposition was performed at room temperature in vacuum with substrates placed at off-axis position. The configuration utilized high density plasma plume arriving at low effective angle for the formation of nanostructured DLC. Nanostructures with maximum size of 50 nm were deposited as compared to the ultrasmooth DLC films obtained in a conventional deposition. The Raman spectra of the films confirmed that the films were diamond-like/amorphous in nature. Although grown at an angle, ion energy of >35 eV was obtained at the off-axis position. This was proposed to be responsible for subplantation growth of sp3hybridized carbon. The condensation of energetic clusters and oblique angle deposition correspondingly gave rise to the formation of nanostructured DLC in this study.

High-temperature epitaxial graphite deposition on macroscopic superaligned carbon nanotube structures by a one-step self-heating method

Carbon ◽  
2021 ◽  
Vol 171 ◽  
pp. 837-844
Author(s):  
Wen Ning ◽  
Peng Lei ◽  
Shiwei Lv ◽  
Yufeng Luo ◽  
Wei Zhao ◽  
...  
Keyword(s):  
High Temperature ◽  
Carbon Nanotube ◽  
Heating Method ◽  
Self Heating ◽  
Graphite Deposition ◽  
One Step

A summary of electromagnetic studies on the Abitibi-Grenville transect

2000 ◽  
Vol 37 (2-3) ◽  
pp. 427-437 ◽  
Author(s):  
David E Boerner ◽  
Ron D Kurtz ◽  
James A Craven
Keyword(s):  
Electrical Conductivity ◽  
Inverse Correlation ◽  
Metamorphic Grade ◽  
Electrical Anisotropy ◽  
Tectonic Deformation ◽  
Conductivity Anisotropy ◽  
Crustal Layer ◽  
Metasedimentary Rocks ◽  
Fluid Saturation ◽  
Graphite Deposition

Electromagnetic surveys on the Abitibi-Grenville Lithoprobe transect have elucidated a number of conductivity signatures that can be genetically linked to Precambrian tectonic processes. Some major fault zones are moderately conductive, possibly signalling graphite deposition from a mantle CO2 flux along crust-penetrating fault systems. However, conductive (graphitic) metasedimentary rocks characteristic of foreland basins are apparently absent from the transect area. A weak inverse correlation between metamorphic grade and electrical conductivity was observed by following rock units across the Grenville Front into high-grade equivalents within the parautochthonous belt. A uniformly conductive mid-crustal layer extends across the Grenville Front, apparently without change in character. The existence of this ubiquitous mid-crustal conductor has been interpreted to mean that electrical conductivity is controlled by the present-day pressure, temperature, and fluid saturation of the lower crust, independent of ancient structure, mineralogy, or metamorphic grade. Lower crustal (upper mantle?) electrical anisotropy is pervasive across the transect area. An apparent spatial correlation of conductivity anisotropy with Archean tectonic deformation patterns has been interpreted to indicate that the lithosphere has remained intact since the Neoarchean.

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