Modification of Zinc-Implanted Silicon by Swift Xenon Ion Irradiation

50 keV ⁶⁴Zn⁺ ions to a dose of 5 × 10¹⁶ cm^–2 are implanted into substrates of single-crystal n-type silicon. Then the samples are irradiated at room temperature with 167 MeV ¹³²Xe²⁶⁺ ions with a fluence ranging from 1 ×10¹² up to 5 × 10¹⁴ cm^–2. Changes in the structure and properties on the sample surface and in its body are studied by scanning electron microscopy, energy dispersive microanalysis, atomic force microscopy, time-of-flight secondary ion mass spectrometry, and photoluminescence.     

Luminescence induced in diamond by He+ ion implantation into SiC/C composites with an inverse opal structure

The photoluminescence induced in diamond by helium ion implantation into SiC/C nanocomposite samples and their structure revealed by high-resolution transmission electron microscopy have been investigated. It has been found that, apart from crystallites of silicon carbide, graphite, and amorphous carbon, in the structure of the composites there are spherical carbon particles containing concentric graphite-like shells (onion-like particles). It has been established that onion-like particles are formed during high-temperature treatment of SiC/C nanocomposites in the course of their preparation. It has been shown that, after the implantation with the subsequent thermal treatment, nanocomposite samples exhibit a luminescence characteristic of N-V centers in diamonds. The assumption has been made that the diamond crystallites are formed at the center of onion-like particles during high-temperature treatment of the composite.     

Effect of fire retardants on fire-resistance and adhesion properties of epoxy urethane compositions

The results of investigating the effects of various fire retardants on the fire-resistance of epoxy urethane compositions are presented. It is shown that the simultaneous presence of phosphorus and bromine, as well as oxides and hydroxides, favors efficient coke formation and a reduction in combustibility while retaining the physicomechanical characteristics of an epoxy urethane adhesive.     

Surfactant properties of cesium in molecular beam epitaxy of GaAs(100)

The experimental and ab initio investigations of the effect of a decrease in the binding energy of surface arsenic atoms under the cesium adsorption on an As-stabilized GaAs(001)-(2 × 4) surface have been performed. The cesium-induced redistribution of the charge on the surface atoms reduces the electron density in the As-Ga bond of the upper layer of the GaAs(001) surface; thus, the As-Ga binding energy decreases and, as a result, the diffusion activation energy, as well as the arsenic atom desorption, decreases. An increase in the diffusion coefficient of surface atoms, along with the property of Cs to segregate on the surface of a growing semiconductor film, makes it possible to use cesium as a surfactant in the low-temperature growth of GaAs by molecular beam epitaxy.     

Kinetics of austenite decomposition upon cooling of low-alloy pipe steel from the intercritical temperature range

High-rate dilatometry is used to study the kinetics of decomposition of undercooled austenite of low-alloy pipe steel 13KhFA obtained upon heating into the single-phase γ field and the intercritical temperature range. The complex effect of the austenitizing in the intercritical temperature range on the decomposition of the undercooled austenite is revealed (the initial temperature of decomposition falls while the temperature of decomposition termination rises).     

Optical Phonon Spectrum of the Ge2Sb2Te5 Single Crystal

JETP Letters - Raman scattering by optical phonons of the Ge2Sb2Te5 single crystal grown by the Bridgman method is studied for the first time. Another method for obtaining this compound based on...     

Stress Concentration in a Soft Ferromagnetic with an Elliptic Inclusion in a Homogeneous Magnetic Field

The paper addresses a stress–strain problem for an infinite soft ferromagnetic body with an elliptic inclusion. The body is in a homogeneous magnetic field B ₀₁. The basic stress–strain characteristics and induced magnetic field in the body and inclusion are determined and their features in the neighborhood of the inclusion are studied. The magnetoelastic and Maxwell stresses are plotted against the ratio of ellipse axes and the latitude angle. Maximum stresses versus magnetic induction and mechanical and magnetic properties of the material are tabulated     

Flame structure of composite pseudo-propellants based on nitramines and azide polymers at high pressure

The chemical and thermal structures of flame of composite pseudo-propellants based on cyclic nitramines (HMX, RDX) and azide polymers (GAP and BAMO–AMMO copolymer) were investigated at a pressure of 1.0 MPa by molecular beam mass spectrometry and a microthermocouple technique. Eleven species H₂, H₂O, HCN, CO, CO₂, N₂, N₂O, CH₂O, NO, NO₂, and nitramine vapor (RDX_v or HMX_v), were identified, and their concentration profiles were measured in HMX/GAP and RDX/GAP pseudo-propellant flames at a pressure of 1 MPa. Two main zones of chemical reactions in the flame of nitramine/GAP pseudo-propellants were found. In the first, narrow, zone 0.1 mm wide (adjacent to the burning surface), complete consumption of nitramine vapor and NO₂ with the formation of NO, HCN, CO, H₂, and N₂ occurs. In the second, wider high-temperature zone, oxidation of HCN and CH₂O by NO and N₂O with the subsequent formation of CO, H₂, and N₂ takes place. The leading reactions in the high-temperature zone of flame of nitramine/GAP pseudo-propellants are the same as in the case of pure nitramines. In the case of nitramine/BAMO–AMMO pseudo-propellants a presence of carbonaceous particles on the burning surface did not allow us to analyze the zone adjacent to the burning surface, therefore only one flame zone was found. Temperature profiles in the combustion wave of nitramine/azide polymer pseudo-propellants were measured at 1 MPa. The data obtained can be used to develop and validate a self-sustain combustion model for pseudo-propellants based on nitramines and azide polymers.     

Alkoxysilyl derivatives of polyhedral oligosilsesquioxanes containing amino and hydroxyl groups and sol-gel hybrid materials on their basis

A mixture of polyhedral oligosilsesquioxanes of the empirical formula [(HOCH₂CH(OH)CH₂)₂N(CH₂)₃SiO_1.5] _n characterized by narrow molecular-mass distributions has been synthesized by the hydrolytic condensation of the product resulting from the interaction of glycidol and 3-aminopropyltriethoxysilane. The said oligosilsesquioxanes have been involved in reaction with 3-isocyanatopropyltriethoxysilane to give rise to urethane-containing alkoxysilyl derivatives of various degrees of substitution. Organo-inorganic hybrids have been prepared on their basis through the sol-gel method. The structure and properties of the products have been studied by matrix laser desorption/ionization mass spectrometry, GPC, X-ray diffraction, DSC, and thermogravimetry. It has been demonstrated that the properties of the polymer materials thus prepared may be controlled by variation of the ratio of hydroxyl and alkoxysilyl groups in oligosilsesquioxane derivatives and by incorporation of low-molecular-mass sol-gel precursors.