Arc Discharge Synthesis Research Articles

The plasma assisted synthesis and high pressure studies of the structural and elastic properties of metal nitrides XN (X = Sc, Y)

This paper investigated the arc discharge synthesis of ScN and YN and the high pressure behaviors of the samples.

Arc Discharge Synthesis of Oxides and Carbides of Tungsten and Aluminum

Experimental investigations of the possibility of arc discharge method for synthesis of nanoparticles of oxides and carbides of tungsten and aluminum have been presented. The method is based on anode atomization of composed graphite – aluminum and graphite – WO3 electrodes. The transmitted electron microscopy, thermal gravimetric analysis and X-ray diffraction were applied for the characterization of morphology and properties of synthesized materials. It was experimentally shown the arc discharge method allows to syntheses the nanoparticles of oxides and carbides of tungsten and aluminum

Temperature measurements in arc-discharge synthesis of nanomaterials dedicated for medical applications

The article presents the plasma synthesis method of carbon nanotubes using an electric arc discharge. In this method different carbon nanotubes are produced as a cathode deposit growth or are deposed on various substrates such as silicon, metals and other materials. The examples of applications of carbon nanotubes in medical applications were presented. Conditions required for the synthesis of carbon nanotubes and process parameters were mentioned. Applications of carbon nanotubes for cancer treatment were discussed. The method of temperature measurement of the arc was described.

In situ grown graphene-encapsulated germanium nanowires for superior lithium-ion storage properties

Alloying anode materials (Si, Ge, Sn etc.) in lithium-ion batteries usually suffer from a remarkable loss of capacity during the charge–discharge cycling. Herein, homogeneous in situ-grown graphene-encapsulated Ge nanowires are successfully achieved by a simple, completely catalyst-free route via arc-discharge. The Ge@G composite is composed of a graphene sheath and a metallic Ge nanowire core. This unique composite of graphene-encapsulated Ge nanowires is an ideal anode material for lithium ion storage. It can exhibit excellent electrochemical performance with a reversible specific capacity of 1400 mA h g−1 after 50 cycles at a current density of 1600 mA g−1 (the theoretical specific capacity of Ge is 1624 mA h g−1). These encouraging results demonstrate that arc-discharge synthesis provides efficient graphene encapsulation of Ge nanowires, and graphene encapsulation is a feasible solution to protect electrode materials for lithium-ion storage.

Characterization of RF Discharge in Liquid n-Hexane and its Application to Synthesize Carbon Nano-Particles

The RF plasma discharge in liquid n-hexane is used to synthesize carbon nanoparticles. The results show that amorphous carbon nanoparticles with size of 5–25 nm are the main product in the plasma in liquid n-hexane. Carbon nano-tubes of average diameter of 19 nm and length of 500 nm are also observed. The energy efficiency for carbon nanoparticles production is 2.9 mg/kJ which is more than 10 times larger than that of typical arc discharge synthesis method. The high speed observation indicates that the RF plasma in liquid has an alternating behaviour and it does not continuously emit light. The OES results show that H and C2 are the main observed species in the plasma. Based on the OES data, it is shown that plasma temperature is 4,030 K and the electron density is 2.54 × 1022 m−3. Our results suggest that this method can be considered as a new route for carbon nanostructures production.

Arc plasma synthesis of carbon nanostructures: where is the frontier?

In this perspective paper, we critically analyse the state-of-the-art of arc discharge technique of carbon nanoparticle synthesis. We discuss improving controllability of the arc discharge synthesis of carbon nanotubes, synthesis of graphene as well as general understanding of the synthesis process. Fundamental issues related to relationship between plasma parameters and carbon nanostructure characteristics are considered. Effects of electrical and magnetic fields applied during single-wall carbon nanotube synthesis in arc plasma are explored. Finally our personal opinion on what future trends will be in arc discharge synthesis is offered.

Up-conversion emissions of Er3+-Yb3+ codoped Al2O3 nanoparticles by the arc discharge synthesis method

The Er3+-Yb3+ codoped Al2O3 nanoparticles with an average particle size of about 50 nm have been synthesized by an arc discharge synthesis method. The green and red up-conversion emissions centered at about 526, 547 and 677 nm, corresponding respectively to the 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, were detected by a 978-nm semiconductor laser diode excitation. The Annealing has evident effect on the up-conversion emissions of the samples: The red up-conversion emission is noticeable before annealing; however, the green up-conversion emission becomes predominant after annealing. The mixture of (Er,Yb)3Al5O12 and α-(Al,Er,Yb)2O3 phases is more favorable for green up-conversion emissions due to an enhancement of the ESA (I) of 4I11/2+a photon→4F7/2 and ET (III) of 2F5/2(Yb3+)+4I11/2(Er3+)→2F7/2(Yb3+)+4F7/2(Er3+) processes. The two-photon absorption up-conversion process is involved in the green and red up-conversion emissions. The results have proved that arc discharge synthesis is a new promising preparation technology for optical materials.

Release of Metal Impurities from Carbon Nanomaterials Influences Aquatic Toxicity

Few studies have considered the environmental impacts of impurities and byproducts associated with low-efficiency nanomanufacturing processes. Here, we study the composition and aquatic toxicity of low-purity, as-produced fullerenes (C60) and metallofullerene waste solids, both of which were generated via arc-discharge synthesis. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and inductively coupled plasma mass spectroscopy (ICP-MS) were used to characterize the metals composition of the solid test materials and of aqueous leachates prepared by mixing test materials with waters of varying pH, hardness, and salinity. The aquatic toxicity of the leachates was determined using U.S. Environmental Protection Agency recommended aquatic bioassay protocols with two standard test organisms-Pimephales promelas and Ceriodaphnia dubia. Results indicated that metals associated with the solid test materials became mobilized in our test system upon interaction with waters of circumneutral pH and reached concentrations sufficient to induce toxicity in both test species. Acute (48 h) LC50 values for P. promelas and C. dubia exposed to leachates prepared from metallofullerene waste solids were 54 and 5% (as % leachate in diluent), respectively. Toxicity was eliminated after adding the chelator EDTA to the leachates, implicating divalent transition metals as the toxicity source. Our results demonstrate the aquatic toxicity of metals mobilized from products and byproducts of nanomanufacturing, and they emphasize the need for a global review of nanomanufacturing wastes and low-purity products.

Effect of Surface Morphology and Adhesion Force on the Field Emisson Properties ofCarbon Nanotube Based Cathode

The effects of the field emission property in relation to the surface morphology and adhesion force were investigated. The single-wall-nanotube-based cathode was obtained by use of an in-situ arc discharge synthesis method, a screen-printing method and a spray method. The morphologies of the formed emitter layers were very different. The emission stability and uniformity were dramatically improved by employing an in-situ arc discharge synthesis method. In this study, it was confirmed that the current stability and uniformity of the field emission of the cathode depend on the surface morphology and adhesion force of the emitters. The current stability of the field emission device was also studied through an electrical aging process by varying the current and electric field.

Arc discharge synthesis and up-conversion emissions of Er 3+ doped Al 2O 3 nanoparticles

The Er 3+ doped Al 2O 3 nanoparticles with an average particle size of about 50 nm have been synthesized by an arc discharge synthesis method. The strong up-conversion emissions centered at about 526, 547, and 668 nm were detected by a 978 nm laser diode (LD) excitation. The evident effect of annealing on the up-conversion emissions of the samples was studied. Before annealing, the red up-conversion emission was noticeable because of a high transition probability of the 4I 13/2 + a photon → 4F 9/2. However, the green up-conversion emission became predominant due to an enhancement of the 4I 11/2 + a photon → 4F 7/2 and 4I 11/2 + 4I 11/2 → 4F 7/2 processes after annealing. The results proved that arc discharge synthesis is a new promising preparation technology for optical materials.

AC arc discharge synthesis of single-walled nanohorns and highly convoluted graphenesheets

In this paper we report the synthesis of single-walled carbon nanohorns (SWNHs)and highly convoluted graphene sheets by AC powered arc discharge in air. Theexperimental strategy was based on the design of an experimental set-up able toenhance the synthesis of these compounds at the expense of the usually foundcathode crust where multi-walled nanotubes are often found. In this set-up the arcdischarge is ignited between pure graphite electrodes experiencing a symmetricalsituation as far as the heat generation by the arc and the heat dissipation atthe heat sinks is concerned. This is achieved by AC powering two electrodes ofthe same size and length. A cylindrical steel collector able to control the heatexchange with the surroundings completes the experimental set-up. The yieldof the device, in terms of synthesis rate and of fraction of sublimated carbonconverted to nanostructures, has been evaluated, and it resulted in being particularlyhigh, indicating that AC powering can represent a key factor in the large-scalesynthesis of SWNHs and highly convoluted graphene sheets by arc discharge. Thestructure of the synthesized powder has been determined by transmission electronmicroscopy.

New DC Arc Discharge Synthesis Method for Carbon Nanotubes Using Xylene Ferrocene as Floating Catalyst

A new synthesis method, a floating catalyst technique, was studied to produce carbon nanotubes in a DC arc discharge process. Xylene ferrocene was directly introduced into a DC arc chamber using a carrier gas. Experimental results showed that both multiwalled carbon nanotubes (MWNTs) and singlewalled carbon nanotubes (SWNTs) can be synthesized by this technique. The numbers of synthesized MWNTs and SWNTs varied depending on process conditions such as the flow rate of ferrocene, pressure, process current, and voltage. The yield of SWNTs was improved by increasing the flow rate of xylene ferrocene owing to the high density of the catalyst precursor used; however, it was reduced by decreasing the process current owing to the poor activation ability of the catalyst.

Column: General Topics

Carbon nanotubes, CNTs, have probably been made in small amounts since the first fires reduced trees and organic material to ashes. It was not until recently, as part of the so-called nano revolution, that we first recognized the existence of these nanotubes. Sumio Iijima, NEC Fundamental Research Laboratory in Japan, first observed carbon nanotubes as by-products of the arc-discharge synthesis of fullerenes. Although there are many different nanotubes, we will focus on only carbon nanotubes. Carbon nanotubes are carbon allotropes that have attracted much attention. Some have suggested that carbon nanotubes will be one of the most important twenty-first century materials because of the exceptional properties and ready abundance of the feedstock, carbon.

UV–VIS–NIR spectroscopy study of sensitivity of single-wall carbon nanotubes to chemical processing and Van-der-Waals SWNT/SWNT interaction. Verification of the SWNT content measurements by absorption spectroscopy

Spectrophotometric measurements of a large number of suspensions of SWNTs-containing soots in aqueous solutions of a surfactant with known weight/volume ratio have been carried out. SWNTs were purified by two methods, by gas-phase oxidation and by centrifugation of suspension. In contrast with gas-phase oxidation, centrifugation does not lead to chemical modification of SWNTs and to irreversible waste of substance. It was shown that gas-phase oxidation, as compared with centrifugation, weakly (by 5%) enriches samples (in which more than 60% of SWNTs were burned) by SWNTs with large diameters. Gas-phase oxidation of nanotubes produces no shift of the van Hove singularity peak positions of solitary nanotubes. It increases relative height of the van Hove bands of solitary nanotubes due to predominant combustion of defective nanotubes. The red shift of the van Hove singularity peaks can be used as a qualitative measure of agglomeration. Comparison of suspension spectra after powerful centrifugation at 160 000g (spectra of solitary nanotubes) shows that different catalysts of the arc discharge synthesis (Ni/Co, Ni/Y, Ni/La, Ni/Ce, Ni/Gd, Ni/Pr) produce almost the same diameter set of SWNTs, but with different distribution. A careful examination of the spectrophotometric method of determination of the abundance of SWNTs in aqueous surfactant suspensions with known weight/volume ratio was carried out.

Electron microscopy of carbon nanotubes

High-resolution electron microscopy was used to study multiwall carbon nanotubes obtained by the arc-discharge technique and double-and single-wall nanotubes produced by the arc-discharge catalytic synthesis. The structure of conical layer nanotubes obtained by the CVD technique is characterized in detail. It is established that heat treatment of nanotubes gives rise to their structural changes. The structure of nanotubes obtained by carbon evaporation in the N2-Ar atmosphere under high pressure is determined. A new type of nano-and microtubes with surface-modulated walls is revealed. Possible applications of carbon nanotubes are reviewed.

Characterization of Fe–Ni(C) nanocapsules synthesized by arc discharge in methane

Ultrafine Fe–Ni(C) particles of various compositions were prepared by arc discharge synthesis in a methane atmosphere. The particles were characterized by x-ray diffraction, transmission electron microscopy, energy disperse spectroscopy, chemical analysis, x-ray photoelectron spectroscopy, Mössbauer spectroscopy, and magnetization measurement. The carbon atoms solubilizing at interstitial sites in γ–(Fe, Ni, C) solution particles have the effects of forming austenite structure and changing microstructures as well as magnetic properties. A carbon layer covers the surface of Fe–Ni(C) particles to form the nanocapsules and protect them from oxidization. The mechanism of forming Fe–Ni(C) nanocapsules in the methane atmosphere was analyzed.

Characterization of ultrafine -Fe(C), -Fe(C) and Fe3C particles synthesized by arc-discharge in methane

Ultrafine gamma-Fe(C), alpha-Fe(C) and Fe3C particles were prepared by arc-discharge synthesis in a methane atmosphere. The phases, morphology, structure and surface layer of the particles were studied by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) techniques and X-ray photoelectron spectroscopy (XPS). It was found that the mean particle size ranged from 9.8 to 12.8 nm. The surface of particles mostly consisted of a carbon layer and a little oxide. Phase transformation from gamma-Fe(C) to alpha-Fe(C) was studied by annealing in vacuum and by differential thermal analysis and thermogravimetry (DTA-TGA) measurement. The abundance of gamma-Fe( C) was determined by a magnetization measurement to be approximately 30%. Phase transformation occurred between 300 and 500 degrees C in a flowing argon atmosphere. The Fe3C particles oxidized to alpha-Fe2O3 and carbon dioxide at 610 degrees C or so. (C) 1998 Chapman & Hall.

Arc discharge synthesis of uniform thickness diamond coatings on large areas

Abstract A gas-dynamical method for correction of the temperature field and, simultaneously, of the atomic hydrogen concentration field in the plasma jet near the substrate is developed. An investigation of two operation modes of the gas-vortex plasmatron with gas-dynamical fixation of its arc length is carried out: the first mode with an anomalous expansion of the plasma jet and the other with the absence of plasma jet-expansion. It is shown that the use of the above mentioned method for the case of the second operation mode provides the uniform diamond coating (DC) deposition over the diameter about 28 mm and simultaneously increases the DC synthesis effectiveness.

Boron nitride nanotubes with reduced numbers of layers synthesized by arc discharge.

A new route to the successful arc-discharge synthesis of pure boron nitride (BN) nanotubes is presented. The carbon-free plasma is established between ${\mathrm{HfB}}_{2}$ electrodes in a nitrogen atmosphere. This technique leads to the formation of BN nanotubes with very few layers including single- and double-layer tubes. Electron-energy-loss spectroscopy yields a B:N ratio of approximately 1. Most tube ends are closed by flat layers perpendicular to the tube axis. A closure by a triangular facet, resulting from three 120\ifmmode^\circ\else\textdegree\fi{} disclinations, is proposed to account for this specific shape.