Effect of Electrochemical Treatment on Electrical Conductivity of Conical Carbon Nanotubes

Interaction of conical carbon nanotubes (CNTs) with hydrogen during electrochemical treatment and its effect on their electronic properties was studied. The temperature dependencies of electroconductivity of initial and electrochemically hydrogenated conical CNTs were investigated by using four-probe van der Pauw method. The studies revealed that the electrochemical hydrogen absorption leaded to a significant reduction in the electroconductivity of conical carbon nanotubes. We assume that these changes can be associated with a decrease in the concentration of charge carriers as a result of hydrogen localization on the carbon π-orbitals, the transition from sp2 to sp3 hybridization of conical CNTs band structure, and, therefore, a metal-semiconductor-insulator transition

Mössbauer effect studies of thin iron films synthesized by ion beam assisted deposition technique

© 2018 Institute of Physics Publishing. All rights reserved. The paper presents the results of Mössbauer effect studies of thin iron films obtained by ion-assisted deposition technique. It was found that the films obtained consist of several phases and have a perpendicular magnetic anisotropy. Magnetization direction can be changed by external magnetic field in sample plane

Development of technology for high-speed branding of titanium alloys

© Published under licence by IOP Publishing Ltd. Electrochemical stamping produces an oxide film on the titanium surface, which slows down the stamping process. In this paper, the task was set to develop technological methods that accelerate the process of stamping titanium alloys. Studies have shown that markings obtained from an electrolytes given in the work and according to the regime described in the work are stable, clear, contrasting, different in color from the base metal. The resulting marks have withstood repeated sterilization by boiling in water and a moisture resistance test

Investigation of a nickel coating deposition processes from solid nickel electrolyte

© Published under licence by IOP Publishing Ltd. Nickel is the basis of most of the heat-resistant materials used in the aerospace industry for power plant parts. Recently, the method of electrolytic coating with nickel is used to create protective coatings on aluminum, magnesium, zinc and cast irons. It is known to use the method of nickel plating of aluminum and magnesium alloys, in particular to protect the duralumin blades of screw aircraft. The lifetime of nickel-plated cast-iron drums for drying in paper production is significantly higher than in conventional cast iron, and paper quality is also improving. The aim of the work is to influence the concentration of hypophosphite on the kinetics of the cathode process and on the properties of the resulting nickel coating

Research of bi-nickel coatings obtaining process

© Published under licence by IOP Publishing Ltd. Modern machine building industry can't be without the use of special coatings, which allow increasing the physical and mechanical properties of the product. Nickel coatings are widely used, due to wear resistance and corrosion resistance. Black nickel coatings began to be used in solar power engineering, for efficient conversion of solar energy into thermal energy. Also nickel coatings are used in the manufacture of medical instruments. To improve the physical and mechanical properties of nickel coatings, the task was to study the possibility of creating a bi-nickel coating

On the question of structure of ZnO thin films formed by IBAD and subsequently implanted with silver ions

© 2018 Institute of Physics Publishing. All rights reserved. Nanocrystalline ZnO thin films with a thickness of ∼ 235 nm were synthesized by ion beam-assisted deposition (IBAD) technique using a metal target of zinc and oxygen (O2) as a reactive gas. The near-surface region of the synthesized films was subsequently implanted with 30 keV Ag+ ions in the fluence range of (0.25-1)×1017 ion/cm2 at high ion current density of 12 μA/cm2. The structure parameters and morphology of as-deposited and subsequently implanted with silver ions ZnO films were investigated by X-ray diffraction and scanning electron microscopy techniques. It was found that the as-deposited ZnO films have inhomogeneous structure, which consists of nanocrystallites and disordered amorphous phase. The nanocrystallites of the obtained ZnO thin films have values of lattice parameters higher than for a bulk ZnO. Subsequent implantation with silver ions leads to a significant radiation heating and microstress relaxation of the film as well as to an increase in the size of nanocrystallites due to the amorphous phase

Short-Lived Electron Excitations in FeTe1 – xSex as Revealed by Microwave Absorption

Abstract: The Fe1 + yTe1 – xSex single crystals with the various Se/Te ratios were studied by the microwave absorption and direct current resistivity measurements. The comparison of the microwave absorption data and the resistivity versus temperature made it possible to separate the contributions of two types of spin fluctuations. One of them is due to the anisotropic magnetic (nematic) fluctuations. It is observed over the wide temperature range from ~30 to 150 or 200 K. In FeSe it has the maximum close to the structural transition temperature. Another MWA anomaly is located in the narrow temperature range above the superconducting transition. It is likely due to the antiferromagnetic fluctuations. Annealing of a sample at the temperature around 300°C in the oxygen atmosphere made it possible to exclude the effect of excess iron on the observed anomalies. © 2019, Pleiades Publishing, Inc

Optical properties of ZnO and Al2O3 implanted with silver ions

ZnO and Al2O3 samples implanted with 30-keV silver ions with fluences in the interval (0.25-1.00) × 1017 ions/cm2 are studied by the method of optical photometry in the visible part of the spectrum. The optical transmission spectra of the implanted samples exhibit a selective band associated with surface plasmon resonance absorption of silver nanoparticles. The intensity of this band nonmonotonically depends on the implantation fluence. The silver ion depth distribution in the samples is calculated. It is shown that the non-monotonicity observed in experiments is due to an increase in the substrate sputtering ratio with increasing implantation fluence. It is found that vacuum thermal annealing of the implanted Al2O3 layers up to 700°C causes a considerable narrowing of the plasmon absorption bandwidth without a tangible change in its intensity. At higher annealing temperatures, the plasmon absorption band broadens and its intensity drops. Annealing of the ZnO films under such conditions causes their complete vaporization. © 2014 Pleiades Publishing, Ltd

Effects of nickel ions implantation and subsequent thermal annealing on structural and magnetic properties of titanium dioxide

© Published under licence by IOP Publishing Ltd. Wide bandgap semiconducting rutile (TiO2) doped with 3d-elements is a promising material for spintronic applications. In our work a composite material of TiO2:Ni has been formed by using implantation of Ni+ ions into single-crystalline (100)- and (001)- plates of TiO2. Sub-micron magnetic layers of TiO2 containing nickel dopant have been obtained at high implantation fluence of 1×1017 ion/cm2. A part of the implanted samples was then annealed in vacuum at different temperatures T ann 450-1200 K for 30 min. The influence of the implantation fluence, crystalline orientation, as well as subsequent annealing on the structural and magnetic properties of the nickel-implanted TiO2 have been investigated by using X-ray photoelectron spectroscopy, scanning electron microscopy and coil magnetometry techniques