Growth Of Carbon Nanoparticles Research Articles

NANOPARTICLE SYNTHESIS BY THE PECVD METHOD BASED ON RF DISCHARGE

This scientific paper presents the results of the study of the synthesis of carbon nanoparticles in radio-frequency ( RF ) discharge plasma at low pressures in a vacuum apparatus. The growth of carbon nanoparticles was studied under different plasma parameters, such as variation of self-displacement voltage, temperature, and discharge power. The experiment was performed in the pressure range of 0.5-1.1 mbarr and powers of 6-20 W. The results showed that the synthesis time of carbon nanoparticles, including their formation and growth, depends on the plasma parameters. Small changes in temperature, pressure, and plasma power can significantly change the growth and formation of nanoparticles. An important conclusion of this work is that increasing the temperature of the plasma-forming gas leads to an increase in the formation time of carbon nanoparticles. The dependences of nanoparticle growth on the discharge power, selfdisplacement voltage on the discharge pressure, and temperature on the discharge power were also obtained. The results obtained provide valuable information for understanding and controlling the synthesis process of carbon nanoparticles in the plasma environment. This is important for various technological applications, including nanoelectronics and catalysis.

On the Possibility of Promoting a Detonation Condensation Wave in Acetylene with Methane Additions

A numerical analysis of the recently discovered promoting of the growth of condensed carbon nanoparticles during the thermal decomposition of acetylene in the presence of methane additives has been performed. Calculations carried out using the modern kinetic mechanism, describing the growth of carbon nanoparticles during hydrocarbon pyrolysis and combustion, have confirmed a significant acceleration of the growth of polyaromatic hydrocarbons and nanoparticles, as well as temperature and pressure during shock wave pyrolysis of acetylene with the addition of 10% methane. The results indicate a possible decrease in threshold pressure and acceleration of the development of acetylene detonation in the presence of methane additions.

The growth of carbon nanoparticles during the detonation of trinitrotoluene

In this work we present experimental data on measuring distributions of small- angle X-ray scattering (SAXS) during cast trinitrotoluene (TNT) detonation of 30 and 40 mm in diameter. Dynamics of average size of condensed carbon nanoparticle inkreases has been restored from experimental SAXS data. The work was carried out at the SYRAFEEMA (Synchrotron Radiation Facility for Exploring Energetic Materials) station at accelerator complex VEPP- 4M (Budker Institute of Nuclear Physics). We observe minimal size of particles of order of 2 nm directly behind the detonation front. Later, the average size of carbon nanoparticles increases within 4-12 μs and reach values of 6 nm.

Kinetics of electrical conductivity of TATB detonation products as an indicator of growth of carbon nanoparticles

Two stages of growth of electrical conductivity of detonation products of plastic-bonded TATB are registered: a fast stage with a characteristic time of 0.1 µsec, which is commensurable with the time of chemical reactions, and a subsequent slow stage, which lasts for 0.5–1.0 µsec until specimen unloading begins. Under the assumption of the thermal mechanism of conductivity emergence, the second stage could be caused by an increase in temperature due to slow energy release in the course of growth of carbon nanoparticles in explosion products.

Modeling of a Solar Reactor for Single-Wall Nanotube Synthesis

Experimental results with a 50kW solar reactor producing 10-15g∕h single-wall carbon nanotube’s rich soot have shown that good quality product was obtained with helium and rather bad product with argon. This result is explained using a computational fluid dynamics model of the reactor accounting for fluid flow, heat transfer, and mass transfer. The bad results in argon were linked to the quenching of carbon vapor in the vaporization zone that resulted in the growth of carbon nanoparticles in spite of carbon-metal clusters (single-wall carbon nanotube precursor). By contrast, the vaporized materials (C, Ni, and Co species) at the target surface were well mixed in helium, and single-wall carbon nanotubes (SWNTs) might grow in the annealing and cooling zone at the backside of the reactor. The same numerical approach may be used to design modifications of the reactor in order to favor the growth of SWNTs.