A Procedure for the Deposition of Macrocomponents in Determining Selenium and Tellurium in Metallurgical Materials by Inductively Coupled Plasma Atomic Emission Spectrometry

Journal of Analytical Chemistry - Studies on the separation of the Se and Te trace components from Co, Ni, Cu, Fe, Cr, Mo, and W macrocomponents for their determination by inductively coupled...     

Peculiarities of dislocation generation by block boundaries in alkali halide crystals during ultrasonic vibrations

The generation of dislocations by block boundaries in alkali-halide crystals under the action of ultrasound was investigated making use of a computer defet modeling method. Ultrasonic vibrations were excited in a double piezoelectric oscillator at the frequencies 60 and 73 kHz. Specimens of KCl and KBr with =0° and =30°, where is the angle between the fourfold axis and the propagation direction of the ultrasound, were investigated. The change in the dislocation structure was determined from the volt-ampere characteristics. It was established that the dislocation sources located near the block boundaries started to operate at stress values one third of those at which other sources operated. Modeling showed that the existence of boundaries had a significant effect on the operation of small-size sources. The experimental estimate of the reduction of the critical stress exceeds the theoretical one.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 52–55, March, 1984.     

Asymptotic representations of the solutions of essentially nonlinear nonautonomous second-order differential equations

We establish asymptotic representations for the solutions of a class of nonlinear nonautonomous second-order differential equations. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 60, No. 3, pp. 310–331, March, 2008.     

Magnetic and electrical properties of the half-metallic ferromagnets Co2CrAl

This paper presents the results of measurements of the magnetic and electrical properties of the ferromagnetic alloy Co₂CrAl in two structural states: (i) after severe plastic deformation and (ii) after shortterm high-temperature annealing of the deformed specimens. The experiments have been performed at temperatures in the range from 2 to 900 K in magnetic fields H ≤ 50 kOe. The ferromagnetic Curie temperature T _C and the paramagnetic Curie temperature Θ have been determined (T _C = 305 K and Θ = 326 K), as well as the spontaneous magnetic moment μ _S and the effective magnetic moment μ_eff per molecule of the alloy (μ _S = 1.62 μ_B and μ _eff ² = 8.2 μ _B ² ). It has been shown that the magnetic crystalline anisotropy energy of the alloy is on the order of ～5 × 10⁵ erg/g. The specific features of the electrical properties are associated with the presence of an energy gap in the electronic spectrum near the Fermi level E _F and with the change in the parameters of the energy gap as a function of the temperature.     

Effect of magnetic field on the dislocation structure and mechanical properties of alkali halide crystals deformed by ultrasound

The dislocation structure and mechanical properties of LiF and NaCl crystals under joint action of magnetic field and ultrasound in the range of longitudinal strain amplitudes corresponding to dislocation multiplication have been investigated. Ultrasonic deformation was implemented in a piezoelectric oscillator at a frequency of 80 kHz. It is established that the presence of a magnetic field facilitates cross slip; initiates displacement of block boundaries; and leads to the formation of labyrinth structures (characteristic of high-temperature loading), which strengthen the crystal.     

Specific features of the electrical resistivity of half-metallic ferromagnets Fe2MeAl (Me = Ti,V, Cr,Mn, Fe,Ni)

The transport properties of half-metallic ferromagnetic Heusler alloys Fe₂MeAl (where Me = Ti, V, Cr, Mn, Fe, and Ni are 3d transition elements) have been measured in the temperature range of 4–900 K. The specific features in the behavior of the electrical resistivity have been considered in terms of the two-current conduction model, which takes into account the presence of an energy gap in the electron spectrum of the alloys near the Fermi level.     

Electron-probe X-ray microanalysis of individual particles of solid snow sediment with size factor correction

A technique is proposed for X-ray electron-probe microanalysis (EPMA) of individual particles of solid snow sediment. Two sample preparation procedures were used to analyze the sediments. The PAP-method and the original bi-exponential model were used for matrix correction and the calculation of elemental composition. A method of calculating composition has been developed for approximately spherical individual particles, comparable in size with an area of X-ray generation. An analytical expression is proposed for determining the composition of these particles, taking account of their size. Including the size factor reduces the error of composition determination from 0.5-45 to 0.2-22% relative percent, for particles in the size range 1-3 microm.