Electric Arc Discharge Method Research Articles

Synthesis mechanism of TiO2 nanoparticles via high frequency electrical arc discharge

Abstract The rapid advancement of nanofabrication techniques has significantly increased the utilization of nanoparticles in recent years. This study investigates the synthesis of titanium dioxide (TiO₂) nanoparticles, highlighting their unique properties and diverse applications across scientific and industrial fields. These nanoparticles are valued for their biocompatibility and advantageous optical, electrical, and physical properties. Various synthesis methods—chemical, physical, and biological—are reviewed, with a particular focus on the electric arc discharge method. This method is distinguished by its efficiency and environmental friendliness, enabling the production of highly pure nanoparticles. Utilizing continuous and alternating sparks between two electrodes, the technique generates spherical nanoparticles with adjustable sizes, controlled by the energy of each spark. An RC circuit-based device was designed for this electrical discharge process. Dynamic light scattering (DLS) measurements revealed an average particle size of 164.51 nm with a standard deviation of 44.08 nm. Field emission scanning electron microscopy (FESEM) images showed both solid and hollow spherical TiO2 nanoparticles. Energy dispersive spectroscopy (EDS) confirmed that the TiO2 particles contained only titanium and oxygen, with no other elements detected. X-ray diffraction (XRD) analysis verified the crystal structure, predominantly identifying the anatase phase of the synthesized nanoparticles. This research enhances the understanding of TiO2 nanoparticle synthesis and characterization, providing a foundation for future innovations in their extensive applications.

Arc Discharge Synthesis and Multistep Purification of Multiwall Carbon Nanotubes

This research work describes the cost-effective synthesis and purification of multiwall carbon nanotubes (MWCNTs). Synthesis of CNTs was carried out in distilled water between two electrodes using the electric arc discharge (EAD) method. EAD is a simple and straightforward route in which an electric arc is generated between graphite electrodes through DC power source to produce soot which contains MWCNTs along with impurities. The deposited soot containing MWCNTs was then chipped off and purified. In this case, multistep purification scheme was opted to remove unwanted impurities from produced MWCNTs. Purification route comprised thermal treatment, chemical treatment and a combination of both to yield pure MWCNTs. Thermal treatments were carried out in normal air and under controlled flow of oxygen at different temperatures whereas chemical treatment was performed using acidic solution. Thermo gravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were carried out before and after purification treatments to investigate the outcome of employed treatments. Results showed that the thermal or chemical treatment alone is not sufficient to remove impurities from soot. Moreover, the introduction of an oxide group through chemical treatment reduces the oxidization temperature of graphitic particles. It was found that the chemical treatment followed by thermal annealing under the controlled flow of oxygen is the most appropriate method for successful purification of MWCNTs synthesized via EAD method.

Experimental investigation of the effect of functionalized graphene on the creep behavior of epoxy

The objective of the current work was to investigate the creep behavior of functionalized graphene (f-GNF)-epoxy nanocomposite. Time and temperature-dependent mechanical behaviors were investigated by performing creep tests at three different stress levels and two different temperatures. Graphene produced by the electric arc discharge method was functionalized with Triton X-100 by a non-covalent method. Then, f-GNF-epoxy nanocomposites are produced by using the Three Roll Milling (3RM) method to eliminate nanofiller agglomeration. By performing quasi-static compression tests, stress levels for creep tests are determined as 50, 100, and 200 MPa to guarantee the viscoelastic deformation regime, around yield, and the viscoplastic deformation regime, respectively. The results indicate significant creep resistance in the nanocomposite with 0.1 wt% f-GNF. Depending on temperature and stress level, the effect of f-GNF is more pronounced at higher stresses and temperatures. f-GNFs have a significant effect on inhibiting the mobility of polymer chains, resulting improvements in the creep modulus. This indicates that thermally activated processes controlling the creep rate are in part inhibited by the presence of f-GNF. In the creep tests carried out for 2 h, a maximum improvement of 85% was observed in the creep modulus of epoxy-nanocomposite compared to pure epoxy at room temperature.

The Impact of Gamma Irradiation on Optical Fibers Identified Using Long Period Gratings

This paper compares the impact of gamma irradiation on various optical fibers, where the evolution in their optical properties could be identified using long period gratings (LPG) there induced. The LPGs were fabricated in broad spectrum of commercially available single-mode optical fibers - from standard to unconventional ones - using the electric arc discharge method. The fused silica fiber material contained such dopant as Ge, F, B/Ge and P. The gamma exposure has been performed with a dose rate of 2.6 kGy/h for 20 h (a total dose of 52 kGy). Subsequently, the recovery effect was monitored during the following 48 h. The wavelength shift and power change of the LPG attenuation bands during irradiation were investigated in real time. Moreover, to identify the impact of gamma treatment on the fiber properties, the thermal response of the gratings was studied before and after the irradiation. Depending on the fiber, significant differences have been observed in the grating responses. The highest radiation-dependent resonance wavelength shift has been found for B/Ge fiber (∼10 nm at maximum dose). Moreover, for these LPGs no response saturation within the applied dose levels has been observed together with very low recovery effect, what differentiate these LPGs from the other tested in this experiment. Finally, concerning the changes in optical power at the resonance wavelength, the LPG induced in P-doped fiber has shown a strong irradiation-induced attenuation reaching 18 dB with a negligible recovery effect. The findings reported in this work are crucial for optical fiber and optical fiber sensors application in environments exposed to radiation.

In-house fabrication and detailed analysis of fiber optic long period grating using electric arc discharge method

In-house fabrication and detailed analysis of fiber optic long period grating using electric arc discharge method

Purification of carbon nanotubes produced by the electric arc-discharge method

As-grown carbon nanotubes (CNTs) samples produced by electric arc-discharge method have shown several undesired impurities, such as amorphous carbon, metallic particles and different graphitized carbon materials that prevents their potential use. Therefore, due to the wide variety of impurities present in these samples, the purification process should be carried out in specific steps. For instance, the effective residual catalyst metal nanoparticles removal is a big challenge, since these materials are coated with a graphitic shell which prevents acid treatments from attacking the metals. In this work two different purification protocols based on the combination of gas-phase treatments, followed by the liquid-phase oxidation steps of CNTs with high degree of impurities were investigated. A significant removal of carbon impurities with minimal introduction of defects in the CNTs walls was evaluated, however the presence of active encapsulated metallic particles was still observed. Through TEM, TGA, EDS and XPS analysis, it was possible showed that these metals are encapsulated in different levels of metallic carbides (such as Ni3C), with very difficult removal. Even though the catalytic metals were not completely removed by the protocols used, the combination of the alternating gas phase with the acid treatments ensured CNTs samples with structural integrity and impurities removal of up to 75%.

Experimental investigation of oligo cyclic compression behavior of pure epoxy and graphene-epoxy nanocomposites

The loading–unloading compression behavior and the oligo cyclic behavior of pure epoxy and graphene-epoxy nanocomposites are investigated since the systematic evaluation of the mechanical behavior under cyclic loading is of great importance in the development of damage characterization and fatigue models for polymer composites. High purity graphene nanoflakes (GNF) are synthesized by electric arc discharge method, and the manufacturing of graphene epoxy nanocomposites is done using solution blending. The structural characterizations of produced GNF are performed using several techniques such as transmission electron microscopy (TEM), Raman spectroscopy and Brunauer–Emmett–Teller (BET). Oligo quasi-static strain-controlled cyclic tests are performed at the elastic (or viscoelastic) region, around yield and after softening at the viscoplastic region. Comparing the behavior under compression, loading–unloading and oligo (repeated) cycled reveals that prehistory does not have much effect on the subsequent behavior. The change in the elasticity modulus during repeated cyclic compression is determined. It is observed that elasticity modulus decreases initially, and then, it progressively increases with the increase in applied maximum strain. Compared to epoxy, the yield stresses of graphene-epoxy decrease in both strain rates and a small increase in the elasticity modulus of graphene-epoxy is observed at low strain rate (1.E-4 /s).

Analysis of boron carbide powder by high resolution transmission electron microscopy

We have reported the experimental results on analysis of a powder based on boron carbide. The powder was obtained by a non-vacuum electrical arc discharge method and analyzed by high resolution transmission electron microscopy. According to the results of analysis, boron carbide particles coated with a graphite-like carbon shell were identified in the powder, respectively, the particles are characterized by a core-shell structure.

High-sensitivity dual-direction weak magnetic field sensor based on structural modulated ultralong period microfiber grating

A high-sensitivity optical fiber dual-direction weak magnetic field sensor based on a structural modulated ultralong period microfiber grating (SULPMG) is proposed. The SULPMG was fabricated by an electric arc discharge and flame-heating drawing method, and the sensor was fabricated by cascading the SULPMG with a core offset section. By tuning the direction of an applied magnetic field, the refractive index of a magnetic fluid (MF) can be tuned accordingly. The transmission spectral response of the proposed sensor was measured and analyzed. For the weak magnetic field intensity range from 0 mT to 7 mT, the obtained magnetic field sensitivity is −1.759 nm/mT and 1.082 nm/mT when the magnetic field is perpendicular or parallel to the light propagation direction, respectively. Theoretical analysis shows that reducing the waist diameter can further improve the sensitivity of the sensor. The proposed sensor is expected to be applied to weak magnetic field measurements in the aviation, vehicle detection and biomedical fields.

Supercapacitor behavior of carbon‐manganese oxides nanocomposites synthesized by carbon arc

The Mn-C-O composites were synthesized by the electric-arc discharge method. The composite materials were obtained by spraying of graphite electrode with the addition of MnO2. The morphology of Mn-C-O composites formed during electric-arc spraying of metal-carbon electrodes in various buffer gases (N2 and He) and the effect of their subsequent annealing in an oxygen-containing atmosphere was studied. It was experimentally determined that MnOx (MnO, Mn3O4) nanoparticles are mainly formed in N2 atmosphere, and Mn7C3 carbide nanoparticles are formed in He atmosphere. This phenomenon is explained by different cooling rates of the formed composites. With further annealing of materials, partial oxidation of nanoparticles and graphitization of the carbon matrix occur due to the thermal effect of the oxidation reaction. According to the study of electrochemical activity of materials in the 1 M KOH aqueous electrolyte, the materials with a higher MnO content and a higher degree of soot graphitization have the highest electrochemical capacity of 135 Fg−1.

Boron and nitrogen doping in graphene: an experimental and density functional theory (DFT) study

Boron (B) and Nitrogen (N) doped few layer graphene (BNG) is directly synthesized via electric arc discharge (EAD) method. NH3 and BCl3 gas mixtures are used in the synthesis atmosphere. Raman spectroscopy is used to determine graphene’s purity and number of layers. The investigation of structure and morphology of pristine graphene and BNG are carried out via Transmission Electron Microscopy (TEM). The presence of B and N in the structure of graphene is detected by Energy Dispersive X-ray Spectroscopy (EDS) analysis. Elemental mapping show that N and B are distributed homogeneously in the graphene structure. It is observed that doping process did not affect the positions of the D, G and 2D bands in the Raman spectroscopy. The effect of doping on the number of layers of graphene is found negligible. TEM results exhibit that pristine graphene and BNG have 5 to 6 layers. Besides, the theoretical calculations based on Density Functional Theory (DFT) are employed to support experimental studies. Theoretical results based on DFT showed that bonding of B and N is favorable.

Tapered Optical Fiber Sensor for Discrimination of Strain and Temperature

A simple Mach-Zehnder interferometer (MZI) based on a standard single-mode fiber for simultaneous strain and temperature sensing was proposed and demonstrated experimentally. The interferometer was fabricated by electrical arc discharge method in which a portion of the standard single-mode fiber was heated and stretched. Any special type of fiber or a particular splicer was not required to form the MZI and it indicated high resolution. To find the modes that contributed to the interference spectrum, Fourier analysis was done and the spatial frequency versus normalized intensity plot showed that LP02 was the excited dominant higher order cladding mode. Coefficient matrix was realized for simultaneous measurement of strain and temperature ability of such an MZI. For discrete measurements, a resolution of 0.79 °C in temperature and 1.18 micro-strain can be achieved for 10 pm wavelength resolution. This extremely simple, low-cost sensor easily fabricated with good repeatability is a good candidate in diverse sensing applications.

Reconfigurable Inter-Core Signal Switching Within Multicore Fibers Based on Long-Period Gratings

For future-oriented space-division multiplexing (SDM) networks based on multicore fibers (MCFs), intentional inter-core signal coupling and reconfigurable switching are desired to transfer signals between cores and establish various network topologies. In this paper, we inscribed long-period gratings (LPGs) into the MCF using the programmable electrical arc discharge (EAD) method. When the MCF is held straight, the LPGs initiate resonations between core modes and cladding modes for each individual core, with the signals at certain wavelengths transferred among cores through shared cladding modes. When the MCF-LPG is directionally bent, the inter-core power coupling is blocked due to the bending loss. We realized efficient power coupling among three ambient cores in a seven-core fiber at the C-band. The minimum end-to-end insertion loss is 11.3 dB, including that of the fan-in/fan-out multiplexers, and the maximum extinction ratio between the switching ON/OFF states is 39 dB. A six-wavelength SDM coherent transmission system is established to evaluate the performance of signal switching, with each wavelength channel modulated with a 224 Gb/s 16QAM-OFDM signal. The transmission results validate that all spatial output ports have good performances in both switching states, which indicates that reconfigurable inter-core signal switching is feasible for enabling flexible network functions within MCFs.

Based on ZrO2/graphene/ZrO2 Q-switched mid-infrared Er3+:ZBLAN fiber laser

ZrO2 nanoparticles with an average size of ~40 nm are prepared by an electrical arc discharge method. Here, we fabricated a saturable absorber mirror (SAM) by spin-coating ZrO2, graphene and ZrO2 onto a homemade high-reflective mirror. Stable Q-switching operation in Er3+:ZBLAN fiber laser is achieved by using the as-prepared ZrO2/graphene/ ZrO2 SAM. Compared with ZrO2 SAM, the ZrO2/graphene/ZrO2 SAM has a lower Q-switching threshold and wider range of repetition rates. The maximum average output power of 285 mW is obtained with the repetition rate of 106.61 kHz, pulse width of 0.908 µs and timing jitter of 0.514% at the pump power of 4.84 W by using the ZrO2/graphene/ ZrO2 SAM.

Formation of Single-Walled Carbon Nanotube Buckybooks, Graphene Nanosheets and Metal Decorated Graphene

The various carbon nanostructures e.g. single-walled carbon nanotubes (SWCNTs) web, graphene nanosheets and metal nanoparticle decorated graphene sheets have been synthesized in large quantity by electrical arc discharge method under an argon atmosphere. The as-synthesized nanostructures were characterized by different characterization techniques such as XRD, SEM, TEM, Energy dispersive X-ray spectroscopy, Raman and FTIR spectroscopy. The SWCNT webs of length ~6 cm abundantly containing aligned SWCNTs have diameter of about 1.8 nm and form buckybook like structure. Few layer graphene (FLG) sheets were prepared by electric arc discharge of high purity graphite electrodes in a varying argon gas atmosphere (250-500T). The largest areal extent of graphene (with lowest number of layer i.e. four) has been found at 350T argon pressure. A one step method is also reported for the decoration of these graphene nanosheets with iron and nickel nanoparticles through arc discharge method.

Synthesis and characterization of long-CNTs by electrical arc discharge in deionized water and NaCl solution

In this study, electrical arc discharge method is used for the synthesis of multi wall carbon nanotubes (CNTs). The advantages of applied setup for producing CNTs are simplicity, low-cost procedures and avoiding the multistep purification. The experiments were optimized by submerging graphite electrodes inside deionized water and various concentrations of sodium chloride solution. The purpose of this research is to investigate the effect of liquid medium on growth, size and quality of the CNTs structures. The results show that CNTs of 150 Â µm length or larger with high purity and quality without using catalyst are produced on the cathode surface. Furthermore, the quantity of CNTs is influenced by NaCl concentration. Scanning electron microscopy, Raman spectroscopy and X-ray diffraction technique were used to characterize the results.

Carbon Nanofoam by Pulsed Electric Arc Discharges

The aim of this article was to report the carbon nanofoam synthesis by a new method and a new catalytic mixture. Using the pulsed electric arc discharge method, carbon nanofoam was synthesized. The synthesis was carried out in a controlled atmosphere at 200 torr of hydrogen pressure. The pulsed electric arc discharge was established between two graphite electrodes with 22.8 kVA of power and 150 A DC current; the cathode was relatively motionless and was made of a pure carbon rod of 6 mm diameter, and the spinner anode was a pure carbon disc spinning at 600 rpm; over the disc was an annular cavity where the new catalytic mixture of 93.84/2.56/1.43/0.69/1.48 of C/Ni/Fe/Co/S molar fraction was deposited in a geometrically fixed way by 8 catalytic mixture blocks and 8 empty spaces, and the discharge frequency was 80 Hz. After the synthesis was made, the resulting products were deposited on the electrodes, proving that our method can synthesize different carbon nanostructures easily and at low cost.

Size dependence of optical and magnetic properties of nickel oxide nanoparticles fabricated by electric arc discharge method

Abstract Nickel oxide nanoparticles with an average size of between 28 and 62 nm were fabricated by electric arc discharge method. The electric currents of 10, 100, 200, 300 and 400 A and oxygen pressures of 1, 2 and 3 atm. were tested. High yield production was observed for the samples prepared at low arc current. The samples were characterized using XRD and FESEM measurements. XRD results showed that the samples were pure and single phase of nickel oxide with cubic structure. The produced nanoparticles were cubic shaped and the average particle sizes increased by increasing the arc pressure, but decreased by increasing the arc current and their size distributions were uniform. The magnetic measurements confirmed a soft ferromagnetic behavior for the nickel oxide nanoparticles at low field region but the hysteresis loop tended to be antiferromagnetic like for the higher fields. By decreasing the particle size from 62 nm, the coercivity (H c ) increased but decreased when the particle size was less than about 57 nm. Such magnetic behavior which can be common for antiferromagnetic nanoparticles was interpreted based on a core-shell model.

Chitosan coated tungsten trioxide nanoparticles as a contrast agent for X-ray computed tomography

Recent advances have shown that inorganic nanoparticles (NPs) based on heavy elements are highly appropriate for X-ray computed tomography (CT). In this contribution, tungsten trioxide NPs are prepared by the electrical arc discharge (EAD) method in DI water. The effect of chitosan (CTS) and glutaraldehyde (GTA) as coating and cross-linking agent, respectively, on the hydrodynamic size and zeta potential of prepared tungsten trioxide NPs is investigated. It is found that zeta potential increases by increasing the amounts of CTS. Meanwhile, by increasing the volume of glutaraldehyde (GTA), the final particle size increases whereas the zeta potential deceases. Chitosan coated tungsten trioxide demonstrated no significant cytotoxicity at concentration up to 5mg/mL after 24h. Finally, the X-ray attenuation of prepared chitosan coated tungsten trioxide NPs are higher than Iohexol as the commercially available iodinated contrasting agent at the same concentrations.

Multidimensional microstructured photonic device based on all-solid waveguide array fiber and magnetic fluid

Abstract An all-solid waveguide array fiber (WAF) is one kind of special microstructured optical fiber in which the higher-index rods are periodically distributed in a low-index silica host to form the transverse two-dimensional photonic crystal. In this paper, one kind of multidimensional microstructured optical fiber photonic device is proposed by using electric arc discharge method to fabricate periodic tapers along the fiber axis. By tuning the applied magnetic field intensity, the propagation characteristics of the all-solid WAF integrated with magnetic fluid are periodically modulated in both radial and axial directions. Experimental results show that the wavelength changes little while the transmission loss increases for an applied magnetic field intensity range from 0 to 500 Oe. The magnetic field sensitivity is 0.055 dB/Oe within the linear range from 50 to 300 Oe. Meanwhile, the all-solid WAF has very similar thermal expansion coefficient for both high- and low-refractive index glasses, and thermal drifts have a little effect on the mode profile. The results show that the temperature-induced transmission loss is <0.3 dB from 26°C to 44°C. Further tuning coherent coupling of waveguides and controlling light propagation, the all-solid WAF would be found great potential applications to develop new micro-nano photonic devices for optical communications and optical sensing applications.