G. A. Glushchenko

Impedance spectroscopy of high-molecular poly(ethylene) with carbon nanotubes

The impedance spectra of composite materials based on the high-molecular poly(ethylene) modified by carbon nanotubes have been investigated. A numerical method has been proposed for reconstructing the relaxation time distribution function of the active (R) and reactive (C) elements of a sample directly from the experimentally obtained frequency dependence of the real and imaginary components of the impedance. It has been shown that, with an increase in the concentration of carbon nanotubes, the electrical conductivity of the samples under study increases and their impedance characteristics are described by a nonmonotonic relaxation time distribution function.

A method and apparatus for high-throughput controlled synthesis of fullerenes and endohedral metal fullerenes

A method for synthesis of carbon nanostructures in a high-frequency arc discharge in the flow of helium (3–4 L/min) is presented. It is shown that the plasma-chemical synthesis of fullerenes and endohedral metal fullerenes (EMFs) can be controlled by changing helium pressure in the chamber. Temperature and electron concentration along the line normal to the discharge axis decrease upon moving away from the axis to the periphery; the larger the pressure, the sharper is the decrease in these parameters. The optimal helium pressure of 98 kPa was found in obtaining the Gd@C82 EMF which corresponds to the maximal EMF yield of 5 wt %.

Effect of electrode material on impedance spectra of metal-polyethylene structures with carbon nanotubes

The effect of an electrode material on electrical properties of a composite material based on super-high-molecular polyethylene (SHMPE) filled with carbon nanotubes has been studied using impedance spectroscopy. Using the method of replacing the sample by an equivalent electric circuit, it has been found that, depending on the electrode material, a blocking barrier with high active resistance and a space charge region adjacent to it arise in the interface region. It has been shown that the barrier height is controlled by surface electronic states of SHMPE and weakly depends on the electron work function of metal electrodes (Bardeen barrier). The characteristic times of electrical relaxation characterizing bulk and interface regions of the composite under study have been determined.

Nickel-containing carbon nanotubes and nanoparticles prepared in a high-frequency arc plasma

This paper presents the results of an investigation of nickel-containing carbon nanostructures prepared by plasma-chemical synthesis in a carbon-helium plasma jet at atmospheric pressure with the arc fed by a high-frequency current. It is demonstrated that, under these conditions, the conversion of graphite into a carbon condensate reaches 98 wt % and the contents of carbon nanotubes and nickel in this condensate are 72 and 10 wt %, respectively. Sequential treatment with nitric and hydrochloric acids has made it possible to extract purified carbon nanotubes and nickel nanoparticles coated with a carbon shell (approximately 50 nm thick) in which the nickel content is 4 wt %. Data are presented on the diameters of the prepared nanotubes and on the state of carbon in the samples.

Rapid analysis of monolithic substances by atomic emission spectroscopy

Monolithic steel and brass samples have been studied by the method of atomic emission spectroscopy on a specially designed setup that allows the analysis to be performed without preliminary preparation of samples. The analysis takes about 10–15 s. The setup performance is demonstrated by the results of analysis of brass (LOMSh 70-1-005 grade) and remelted steel samples. It was established that monolithic brass contained the admixtures of arsenic (0.003 wt %), antimony (0.005 wt %), and bismuth (0.003 wt %). In monolithic steel, the analysis revealed carbon (0.08 wt %), manganese (0.05 wt %), and silicon (0.3 wt %).

Synthesis and investigation of iron fullerene clusters

Iron fullerene clusters are prepared by plasma chemical synthesis and investigated using electron magnetic resonance. It is shown that these clusters can be prepared both by plasma chemical synthesis of fullerenes with iron and by mixing of a fullerene solution with a powder of iron nanoparticles coated with carbon shells. A liquid chromatographic technique is proposed for separating iron fullerence clusters.

Synthesis and investigation of boron-doped fullerene and scandium-containing fullerene

We report on the plasmachemical synthesis of fullerene derivatives containing boron and scandium. The synthesis was conducted at atmospheric pressure in a carbon-helium plasma jet generated by an RF arc.

Synthesis of 6H-SiC single-crystal nanowires in a flow of carbon-silicon high-frequency arc plasma

Silicon carbide 6H-SiC nanoparticles and nanowires were obtained in carbon-silicon high-frequency arc plasma plasma in a helium atmosphere at a pressure of 0.1–0.6 MPa. It was shown that 6H-SiC nanowires grow from the arc plasma, as well as from the vapor, according to the known mechanism of vapor-solid condensation on a cold surface covered with single-crystal silicon carbide nuclei. The content of silicon carbide nanowires in the condensate reached 60 wt %. The obtained single-crystal silicon 6H-SiC nanowires had the diameter of 15–18 nm and length of 200–600 nm.

Hydrogen sorption by carbon-based substances formed in carbon-helium plasma

Hydrogen sorption by various carbonaceous products formed during arc discharge in carbon-helium plasma has been studied. The main product fractions included a fullerene-containing soot, a fullerene mixture extract, a condensate containing carbon nanotubes, and carbonized aluminum oxide. Molecular hydrogen is most effectively sorbed by single-wall carbon nanotubes contained in the carbon condensate fraction.

Synthesis and properties of plasma-deposited carbon condensates

Structural data, thermal characteristics, and theoretically calculated binding energies are reported for a graphite condensate obtained by carbon deposition from plasma. It is demonstrated that this condensate can be effectively used in self-propagating high-temperature synthesis processes.