Showing papers in "Journal of Surface Investigation-x-ray Synchrotron and Neutron Techniques in 2015"
TL;DR: The structural study of barium hexaferrite (BaFe12O19) whose iron ions are partly replaced by diamagnetic aluminum ions (x = 06) is carried out with the help of the neutron-diffraction method as discussed by the authors.
Abstract: The structural study of barium hexaferrite (BaFe12O19) whose iron ions are partly replaced by diamagnetic aluminum ions (x = 06) is carried out with the help of the neutron-diffraction method Experimental data are acquired in a wide temperature range of 4–730 K via a high-resolution diffractometer, which makes it possible to obtain both precise information on changes in crystalline and magnetic structures and behavioral data on the sample microstructure BaFe114Al06O19 retains the magnetoplumbite structure in the whole temperature range and exhibits the “invar effect,” according to which its bulk thermal-expansion coefficient is close to zero at low temperatures (<150 K) The magnetic structure is defined by the Gorter model with magnetic moments oriented along the hexagonal axis For all nonequivalent crystallographic positions, the magnetic moment of F3+ is close to 4 μB at 4 K The total magnetic moment per formula unit is 156 μB, ie, less than the nominal value of 20 μB This is caused by the fact that diamagnetic Al ions are included in the composition Crystallite microstrains increase insignificantly with temperature due to increasing influence of the magnetic subsystem
83 citations
TL;DR: In this article, two types of fullerene C60 solutions are compared with respect to their structural features and toxic properties, and the results are discussed in terms of their potential in medical and biological applications.
Abstract: In this paper, two types of fullerene C60 solutions are compared with respect to their structural features and toxic properties. The results are discussed in terms of their potential in medical and biological applications. The fullerene cluster state at the nanoscale in these solutions is analyzed by small-angle neutron scattering. Experiments on the cytotoxicity of these systems on Chinese-hamster V-79 cells showed no toxic effects of the solutions.
28 citations
TL;DR: In this article, the regularities of the formation of the structure of silumin irradiated with a high-intensity electron beam in different modes are revealed using optical and scanning electron microscopy.
Abstract: The regularities of the formation of the structure of silumin irradiated with a high-intensity electron beam in different modes are revealed using optical and scanning electron microscopy. The optimum irradiation mode that allows one to increase the fatigue life of this material by a factor of up to 3.5 is determined. The probable causes of the observed effect are investigated.
27 citations
TL;DR: In this paper, the crystal structure of the layered semiconductor TlGaSe2 was studied using neutron diffraction at room temperature and under high pressures up to 4.6 GPa.
Abstract: The crystal structure of the layered semiconductor TlGaSe2 is studied using neutron diffraction at room temperature and under high pressures up to 4.6 GPa. Under ambient conditions the crystal structure of TlGaSe2 is described by monoclinic symmetry with the space group C2/c. In the pressure range P = 0.2–0.9 GPa TlGaSe2 undergoes a structural phase transition without a change in symmetry. The pressure dependences of the lattice parameters and the unit-cell volume are obtained, and the bulk moduli for both phases of TlGaSe2 are calculated.
26 citations
TL;DR: The high radiation resistance of this titanium hydride TiH1.8 composite to photon and neutron radiations is proven and the main characteristics of radiation protection for radiation passing through this material are estimated.
Abstract: The attenuation coefficients of photon and neutron beams passing through a titanium hydride TiH1.8 surface are calculated. The main characteristics of radiation protection for radiation passing through this material are estimated: reduction of the neutron-flux (0.1 < E < 5 MeV) and γ-ray (0.5 < E < 20 MeV) densities and attenuation of the neutron and γ-ray dose rates. The high radiation resistance of this composite to photon and neutron radiations is proven.
19 citations
TL;DR: The features of the anodic plasma electrolytic treatment of commercial titanium in an aqueous ammonium chloride solution with ammonia and glycerol additions are investigated in this paper, where the modified layer comprises an external TiO2 or TiO layer with micropores of up to 100 nm and a diffusion sublayer after nitriding in the solution with the ammonia addition.
Abstract: The features of the anodic plasma electrolytic treatment of commercial titanium in an aqueous ammonium chloride solution with ammonia and glycerol additions are investigated. It is revealed that the modified layer comprises an external TiO2 or TiO layer with micropores of up to 100 nm and a diffusion sublayer after nitriding in the solution with the ammonia addition. It is ascertained that the anodic dissolution of the titanium alloy dominates over its oxidation at treatment voltages reaching 210 V and an ammonium chloride concentration of 100 g/L. This effect is accompanied by a decrease in the sample mass. The sample mass grows due to an increase in the oxide layer exceeding the dissolution losses at higher voltages and ammonium chloride concentrations. It is shown that the corrosion current density in Ringer’s solution can be decreased after commercial titanium is treated in the ammonium chloride and glycerol solution.
19 citations
TL;DR: The topography, composition, and electronic and crystal structures of the surface of SiO2 films fabricated by the implantation of O2+ ions in Si (111) with subsequent annealing are investigated in this article.
Abstract: The topography, composition, and electronic and crystal structures of the surface of SiO2 films fabricated by the implantation of O2+ ions in Si (111) with subsequent annealing are investigated. It is established that at high ion implantation doses (D ≥ 6 × 1016 cm−2), continuous homogeneous polycrystalline SiO2 films form, while at relatively low doses (D = 8 × 1015−4 × 1016 cm−2), SiO2 films with regularly arranged Si nano-areas with a density of 1010–1011 cm−2 form.
14 citations
TL;DR: In this paper, a special cell for single crystal diffraction experiments under applied electric field has been developed and tested and a wide angle scan range provided by the cell allows the data collection in a large volume of the reciprocal space.
Abstract: A special cell for single crystal diffraction experiments under applied electric field has been developed and tested. A wide angle scan range provided by the cell allows the data collection in a large volume of the reciprocal space. Test experiments at synchrotron source for ferroelectric and relaxor single crystals show the possibility to the dependence of both Bragg and diffuse scattering on applied electric field. Further development of insitu diffraction methods with the proposed cell at synchrotronbased and laboratory instruments is discussed.
13 citations
TL;DR: In this article, the theory of the formation of the energy spectra of electrons and light ions reflected form a solid surface is constructed, and it is shown that methods based on the numerical solution of boundary value problems for the transport equation are the most effective.
Abstract: The theory of the formation of the energy spectra of electrons and light ions reflected form a solid surface is constructed. It is shown that methods based on the numerical solution of boundary-value problems for the transport equation are the most effective. The boundary-value problem is solved based on the invariant embedding method. Equations for the reflection coefficients Rk(x, n, n0), describing the flux of atomic particles reflected in the direction n and having experienced k events of elastic scattering are obtained. The obtained results are compared with experimental data, the results of simulation using the Monte Carlo method, and the calculations of other authors.
12 citations
TL;DR: In this article, the results of experimental investigation into modification of the (111) face of a synthetic diamond crystal under high-fluence 30-keV Ar+ irradiation are presented.
Abstract: The results of experimental investigation into modification of the (111) face of a synthetic diamond crystal under high-fluence 30-keV Ar+ irradiation are presented. It is found that irradiation at a temperature of 400°C leads to the formation of a conductive surface layer, which is detected in the Raman spectra as a broad band with a maximum close to the position characteristic of the G peak of graphite at 1580 cm−1. In addition, the intensity of the narrow peak of diamond at 1332 cm−1 decreases by an order of magnitude. Ion irradiation is accompanied by the suppression of the initial photoluminescence and gives rise to weak photoluminescence with a spectrum characteristic of gem diamonds.
12 citations
TL;DR: The structural changes in Fe90Zr10 metallic glass induced by low-temperature annealing are studied by transmission electron microscopy and large and small-angle X-ray diffraction as discussed by the authors.
Abstract: The structural changes in Fe90Zr10 metallic glass induced by low-temperature annealing are studied by transmission electron microscopy and largeand small-angle X-ray diffraction. It is shown that the crystallization of metallic glass is preceded by amorphous phase decomposition giving rise to amorphous regions of different compositions, which form various crystalline phases later. The properties of the structural changes point to the spinodal mechanism of the amorphous-to-crystalline transformation.
TL;DR: In this paper, the effect of ion bombardment on the surface composition and structure of CoSi2/Si nano-films was studied and it was demonstrated that ion bombardment leads to the decomposition of Co Si2 and enrichment of the film surface with Si atoms.
Abstract: The effect of Ar+-ion bombardment on the surface composition and structure of CoSi2/Si nano-films is studied. It is demonstrated that ion bombardment leads to the decomposition of CoSi2 and enrichment of the film surface with Si atoms. After heating at T = 850–900 K, the Si-CoSi2-Si nanofilm system forms.
TL;DR: In this paper, the size distribution of rhenium nanoparticles is bimodal on the surface of multiwalled carbon nanotubes (MWCNTs) using metal organic chemical vapor deposition (MOCVD) technology.
Abstract: The deposition of rhenium nanoparticles on the surface of multiwalled carbon nanotubes (MWCNTs) is conducted by metal organic chemical vapor deposition (MOCVD) technology. The synthesized hybrid materials are analyzed using scanning electron microscopy, high-resolution transmission electron microscopy and powder X-ray diffraction. The dependence of the sizes and shapes of the deposited rhenium nanoparticles on the initial synthesis parameters is established. It is found that the size distribution of rhenium nanoparticles is bimodal on the surface of MWCNTs.
TL;DR: In this paper, a metrological approach to investigate the optical properties, material structure and profile shape of compound refractive lenses (CRLs) is proposed, using X-ray radiography and electron microscopy.
Abstract: A possible metrological approach to investigation of the optical properties, material structure and profile shape of compound refractive lenses (CRL) is proposed. The methods of X-ray radiography and electron microscopy are proposed for characterization of the profile of a refractive lens with a small curvature radius. Investigation of the material for problems of X-ray optics is performed using small-angle scattering and X-ray microscopy.
TL;DR: In this article, a comparative analysis of the formation of radiation-induced defects in semiconductors (silicon and silicon carbide are used as examples) under bombardment with electrons with energies of 0.9 MeV or higher is carried out.
Abstract: A comparative analysis of the formation of radiation-induced defects in semiconductors (silicon and silicon carbide are used as examples) under bombardment with electrons with energies of 0.9 MeV or higher is carried out. Experimental values of the rate of charge-carrier removal at electron energies of 0.9 MeV are less by an order of magnitude than at higher electron energies (6–9 MeV). The formation cross section for primary radiation defects (Frenkel pairs) in this range is almost energy-independent. It is suggested that the reason for this difference is the influence of the energy of primary knocked-out atoms. As the energy of these atoms increases, first, the average distance between genetically related Frenkel pairs increases, and, as a consequence, the fraction of pairs that are not recombined under bombardment increases. Second, the possibility of forming new, more complex, secondary radiation effects appears as the energy of the primary knocked-out atoms increases.
TL;DR: In this paper, the subsurface layer of polyimide films is implanted with 100-keV B+ ions, and it is experimentally demonstrated that ion implantation modifies a thin sub-surface layer on its implanted and reverse sides without changing the bulk properties of polymer.
Abstract: Atomic-force microscopy, indentation, and optical spectroscopy methods are employed to investigate the modification processes whereby the subsurface layer of polyimide films is implanted with 100-keV B+ ions. It is experimentally demonstrated that ion implantation modifies a thin subsurface layer of the polyimide film on its implanted and reverse (unimplanted) sides without changing the bulk properties of polymer. This can be explained by the fact that the rearrangement of metastable defects formed during film fabrication is accompanied by elastic-stress relaxation leading to changes both in the strength and optical properties of the subsurface layers and in the surface morphology.
TL;DR: In this paper, the fractography of copper was studied under creep conditions in a magnetic field of 0.35 T. The qualitative similarity of the fracture surface morphology, formed in the presence of magnetic field and without it, was revealed.
Abstract: The fractography of copper destroyed under creep conditions in a magnetic field of 0.35 T is studied by scanning electron microscopy. The qualitative similarity of the fracture surface morphology, formed in the presence of a magnetic field and without it is revealed. It is shown that in the presence of a magnetic field the average sizes of the formed surface relief in a fiber fracture zone are smaller, and in the radial zone they are larger than that in the corresponding zones of the material deformed under normal experimental conditions. It is revealed that exposure to a magnetic field during the creep deformation mode leads to expansion of the pit size range in the fiber area and to its narrowing in the radial zone. It is found that the application of a magnetic field affects the rate of accumulation and annihilation mechanisms of initiation and defect restructuring of the volume and near-surface layer of copper samples.
TL;DR: In this article, the elemental composition of (3HgSe)0.5(In2Se3) 0.5 crystals (undoped and doped with 3d elements) in the backscattered and secondary electron modes are recorded.
Abstract: Scanning-electron microscope images of the surface of (3HgSe)0.5(In2Se3)0.5 crystals (undoped and doped with 3d elements) in the backscattered and secondary electron modes are recorded. The elemental composition of the crystals is determined by energy dispersive analysis.
TL;DR: It is found that terahertz (submillimeter) radiation can reversibly damage the barrier properties of the membrane and serve as an inducer of the targeted delivery of biologically active compounds into cells, while antioxidants can be modulators of such a process and ensure protection against the adverse effects of electromagnetic waves in this range.
Abstract: It is found that radiation with a wavelength of 130 µm creates conditions for the ingression of vital dyes, which do not cross the intact surface of a cell, i.e., through the plasma membrane. It is likely that damaging effects are caused by the action of activated oxygen metabolites on the membrane, which can result from laser-radiation exposure. To test these hypotheses, antioxidants are added into a saline solution surrounding neurons prior to laser irradiation, in addition to a dye (Lucifer Yellow) that does not cross intact membranes. It is found that the phenolic antioxidant Histochrome considerably reduces the penetration of the dye into the cell. The decreased level of dye ingression into neurons suggests that under the effect of radiation in the submillimeter range, hydrophilic pores are formed in the cell membrane as a result of free-radical processes which can be blocked by antioxidants. It is found that terahertz (submillimeter) radiation can reversibly damage the barrier properties of the membrane and serve as an inducer of the targeted delivery of biologically active compounds into cells, while antioxidants can be modulators of such a process and ensure protection against the adverse effects of electromagnetic waves in this range.
TL;DR: In this article, a spin injection light-emitting diodes based on heterostructures with InGaAs/GaAs quantum wells and a ferromagnetic metal (Co) contact layer are fabricated and studied.
Abstract: Spin injection light-emitting diodes based on heterostructures with InGaAs/GaAs quantum wells and a ferromagnetic metal (Co) contact layer are fabricated and studied. The effect of the penetration of cobalt in GaAs is experimentally detected. It is demonstrated that the use of tunnel-thin (1–3 nm) Al2O3 layers as diffusion barriers leads to a decrease in the concentration of cobalt atoms in the semiconductor surface layers. In diodes with the Co/Al2O3/GaAs contact, circularly polarized radiation is detected, which is caused by the injection of spin-polarized holes from the ferromagnetic contact into the semiconductor.
TL;DR: In this paper, the processes and mechanisms of radiation-defect formation in polymers beyond the track of the implanted ions are considered, and the formation of cone-shaped structures with a height of up to 80 nm and a base diameter of upto 400 nm randomly arranged on the surface of polyimide, polyetheretherketone and polyethylene terephthalate films is observed under γ irradiation and low-dose ion implantation.
Abstract: Modification of the surfaces of polymer films of polyimide, polyethylene terephthalate and polyetheretherketone upon γ irradiation and ion implantation with Ni+, Ag+, Au+, Fe+ and B+ ions at an energy of 30–100 keV in the dose range of 1 × 1015–1.5 × 1017 cm−2 is studied by the atomic-force microscopy. The processes and mechanisms of radiation-defect formation in polymers beyond the track of the implanted ions is considered. The formation of cone-shaped structures with a height of up to 80 nm and a base diameter of up to 400 nm randomly arranged on the surface of the polyimide, polyetheretherketone and polyethylene terephthalate films is observed under γ irradiation and low-dose ion implantation. These structures are observed not only in the field of ion deceleration but also beyond the region of high-energy action at a distance of up to 40 μm. Their formation is due to relaxation of the local elastic compressive stress in the polymer film.
TL;DR: In this paper, the authors synthesize β-SiC thin films on a Si substrate surface by the ion-beam sputtering of a two-component graphite-silicon target.
Abstract: We synthesized β-SiC thin films on a Si substrate surface by the ion-beam sputtering of a two-component graphite-silicon target. The smooth film surface and abrupt SiC film-Si substrate interface allow determination of the SiC film parameters by X-ray reflectometry. The Henke-Gullikson simulation shows that the synthesized SiC0.8 film has a thickness of d = 160 nm, a density of ρ = 3.03 g/cm3, and a roughness of σ = 0.25 nm. X-ray diffraction and IR spectroscopy show the formation of β-SiC crystallites about 5.5 nm in size in the SiO0.8 and amorphous SiO2 layers after annealing at a temperature of 1250°C in an Ar atmosphere with O2 inclusions. Simulation using the Release program shows that etching in HF acid for 5 min leads to the formation of a system containing a smooth high-density thin carbon film. The system composition is C(d = 4.0 nm, ρ = 3.7 g/cm3, σ = 0)/SiC0.8(d = 75.0 nm, ρ = 3.03 g/cm3, σ = 2.0 nm)/a-Si(d = 3.0 nm, ρ = 2.23 g/cm3, σ = 4.5 nm)/Si(d = ∞, ρ = 2.33 g/cm3, σ = 0.6 nm).
TL;DR: In this paper, the results of investigation into the imaging of grooves in silicon with a trapezoidal profile and small side-wall inclination angles, which were obtained using a scanning electron microscope operating in the backscattered electron recording mode, are presented.
Abstract: The results of investigation into the imaging of grooves in silicon with a trapezoidal profile and small side-wall inclination angles, which are obtained using a scanning electron microscope operating in the backscattered electron recording mode, are presented. It is shown that there exist four imaging mechanisms. The first of them is caused by primary electrons of the probe. The next two are related to the multiple scattering of primary and secondary (ionizing) electrons. The fourth mechanism is associated with the interaction between electrons released into free space and the sample relief. The first three mechanisms provide direct image contrast, and the fourth is characterized by opposite contrast.
TL;DR: In this article, the main problems of measuring the roughness of supersmooth surfaces for X-ray optics and an approach developed by us for the metrology and production of optical elements with diffraction-quality reflective surfaces are discussed.
Abstract: The main problems of measuring the roughness of supersmooth surfaces for X-ray optics and an approach developed by us for the metrology and production of optical elements with diffraction-quality reflective surfaces are discussed. Up-to-date data on the roughness obtained upon the polishing of fused quartz are presented.
TL;DR: Ion-beam methods are developed for forming supersmooth aspherical optical surfaces of polished fused quartz with a precision on the level of 3 nm relative to the standard deviation and 0.2-0.3 nm for the mean-square surface roughness in the range of spatial frequencies of 0.01-100 μm−1 as mentioned in this paper.
Abstract: Ion-beam methods are developed for forming supersmooth aspherical optical surfaces of polished fused quartz with a precision on the level of 3 nm relative to the standard deviation and 0.2–0.3 nm for the mean-square surface roughness in the range of spatial frequencies of 0.01–100 μm−1.
TL;DR: In this paper, the results of an investigation into the imaging of rectangular grooves in silicon, which were obtained using a scanning electron microscope operating in the backscattered electron recording mode, are presented.
Abstract: The results of an investigation into the imaging of rectangular grooves in silicon, which are obtained using a scanning electron microscope operating in the backscattered electron recording mode, are presented. Three imaging mechanisms are revealed, and their contributions are separated experimentally. One of the mechanisms is caused by primary electrons of the probe, and the other two are related to the multiple scattering of primary and secondary (ionized) electrons.
TL;DR: In this paper, the deuterium plasma and the walls of a vacuum chamber made from 12Cr18Ni10Ti (0.12% C, 18% Cr, 10% Ni, less than 1% Ti) stainless steel were studied.
Abstract: The patterns of gas exchange between deuterium plasma and the walls of a vacuum chamber made from 12Cr18Ni10Ti (0.12% C, 18% Cr, 10% Ni, less than 1% Ti) stainless steel and irradiated with deuterium atoms in an atmosphere of deuterium with the addition of oxygen or with ions and atoms of a discharge in deuterium with the addition of oxygen are studied. It is demonstrated that irradiation of the surface of stainless steel under the indicated conditions promotes the diffusion of hydrogen from stainless steel; the implantation of deuterium into stainless steel; and the production on the surface and the desorption of H2O, HDO, D2O, HD, and H2 molecules. Almost all oxygen from the gas mixture in the oxygen concentration range from 0.5 to 30 at % is involved in the production of protonated and deuterated water molecules on the surface. When the oxygen concentration in the mixture of deuterium with oxygen is increased, the release of hydrogen from steel is enhanced. The amount of deuterium captured by stainless steel is lower than the amount of hydrogen removed from it. It is demonstrated that the diffusion of hydrogen towards the surface, its reactions with deuterium and oxygen from the working gas, and the trapping of deuterium in steel may be driven by consecutive surface exothermic reactions initiated by the interaction of deuterium atoms and ions with chromium oxide on the surface of stainless steel.
TL;DR: In this article, a model of the formation of contrast by secondary electrons in a helium scanning electron microscope is formulated, and the possibility of contrast amplification via energy filtration of signals from secondary and reflected electrons is demonstrated.
Abstract: Data for the study of various contrasts in the methods of scanning electron and ion microscopy with the energy filtration of signals from secondary and reflected electrons are presented. A model of the formation of contrast by secondary electrons in a helium scanning electron microscope is formulated. The possibility of contrast amplification via energy filtration in a helium ion microscope as well as the chance of recording reflected ions by means of secondary electron detection is demonstrated. The recorded data for the material contrast in low-voltage electron microscopy at various acceleration voltages and different modes of energy filtration are given. The possibility of enhancing or reducing material contrast by means of energy filtration is shown.
TL;DR: In this paper, the results of atomic-force microscopy studies of the surface of samples of the protective coating of spacecraft solar cells made of K-208-glass irradiated with 20-and 40-keV electrons at a flux density of φe = 1010−5 × 1011 cm−2 s−1 and a residual pressure of 10−4 Pa in the vacuum chamber were reported.
Abstract: We report the results of atomic-force microscopy studies of the surface of samples of the protective coating of spacecraft solar cells made of K-208-glass irradiated with 20- and 40-keV electrons at a flux density of φe = 1010−5 × 1011 cm−2 s−1 and a residual pressure of 10−4 Pa in the vacuum chamber. The traces of electrostatic discharges that occur at different irradiation intensities are analyzed. It is established that at φe 2.0 × 1011 cm−2 s−1 discharges flowing mainly along the sample surface prevail.
TL;DR: In this paper, a method for growing arrays of vertically aligned carbon nanotubes and synthesizing a polymer composite based on vertically aligned, horizontally aligned, and unaligned carbon Nanotubes is described.
Abstract: A method for growing arrays of vertically aligned carbon nanotubes and synthesizing a polymer composite based on vertically aligned, horizontally aligned, and unaligned carbon nanotubes is described. The thermal conductivity of polymer composites is studied by the laser-flash method. It is found that filling of the polymer with vertically aligned carbon nanotubes leads to an increase in the thermal conductivity coefficient of the epoxy resin by a factor of 10 and more.