Key Engineering Materials Vol. 806

Abstract: Using the methods of spectral analysis with application of the formalism of the integral function of Lebesgue measures and Kullback's divergence, the structural features of the interfaces of spinning Fe- (Cu, Nb) - (Si, B) tapes with different metalloid contents are investigated. An increase in the total concentration of the metalloid ambiguously affects the nature of the morphology of rapidly quenched alloys. The minimum difference in the statistics of contact and free surfaces, formed in the spinning process, is demonstrated by fusionFe₇₄Cu₁Nb₃Si₁₆B₆.

Abstract: The effect of point defects on the shear rupture resistance in titanium aluminide is investigated by the density functional theory and pseudopotential methods. Vacancies, as well as substitution atoms – tungsten and chromium were considered as points defects. The shear was simulated in the(111) slip plane for two directions, namely [110] and [11-2]. It is shown that for a {111}<110> sliding system, vacancies significantly reduce the shear resistance. However, when alloying element occupies a titanium vacancy, it can partially compensate for this negative effect.

Abstract: The multicomponent Tb_0.2Dy_0.8-xGd_xCo₂ and Tb_0.2Dy_0.8-xGd_xCo_0.9Al_0.1 alloys (x≤0.5) were studied in a large temperature range (80 – 350 K) and fields up to 1.8 T. Temperature dependencies of lattices parameters, surface topology features, Curie temperature and magnetocaloric effect near it, of these polycrystalline cubic Laves phase alloys have been obtained and analyzed. The effect of Gd and Al substitution within the rare earth and cobalt sublattices on the structural and magnetocaloric properties of Tb_0.2Dy_0.8Co₂ has been discussed.

Abstract: We present the simulation results of magnetic 2D and 3D structures with direct (for both of them) and Dzyaloshinskii-Moriya (DMI) (for 2D lattice) interactions in the frame of the Heisenberg model. We have adapted the multipath Metropolis algorithm for systems with complex types of exchange interactions and rough energy landscapes. We show the temperature behavior of magnetization, energy, and heat capacity, and reveal its critical temperatures and order parameter.

Abstract: At current work we present first results of comparative study of the morphology and chemical composition in biomineral particles (phytoliths) of different types of wheat (Volzhskaya, Moskovskaya 39, Primorskaya 40). Optical microscopy reveals 5 morphotypes of phytolith in the stem and spike of wheat Triticum aestivum L. Although, only 3 morphotypes of phytolites were found in all three varieties, and the other 2 morphotypes were found only in some cases. These differences may be sort-specific signs. Various phytoliths have different linear sizes. As demosntrated, even within a sole type of wheat, there appears variability of the phytolitic composition. This fact may have significant implication for practical use of the phytolith analysis.

Abstract: In the work, some heterostructures consisting of two different strontium bismuthates from the following series are investigated: Sr₂Bi₂O₅, Sr₃Bi₂O₆ and Sr₆Bi₂O₁₁. It is shown that the creation of such heterostructures affects both optical and photocatalytic properties. The results obtained are promising for the further development and research of new heterostructures based on two different strontium bismuthates and for studying the characteristics of their photocatalytic activity.

Abstract: The possibility to use the split ring resonator – SRR in a microwave filter design is investigated. SRR is made from non-ferrous metals, is one of the variants of the inclusions in the metamaterial. The periodic SRR structure modifies the permittivity and permeability of the source material, to obtain a negative refractive index. These unique properties are widely used in microwave technology, because they allow to create devices with improved performance and extended functionality. Microstrip line with etched SRR on ground plane is considered. The equivalent circuit model for SRR is shown. The paper presents calculation and comparison of the return and transmission responses for SRR structure with series coupling feed lines and with parallel coupling feed lines. The basic relationships for calculating the S-parameters (the return S₁₁(F) and transmission responses S₂₁(F)) are given. S-parameter calculation is made. When the reflection coefficient S₁₁(F) reaches the maximum value, and the transmission coefficient S₁₁(F)- the minimum, the filter operates at the resonance frequency Fp. Simulation are made using the software of Microwave Office. The results are presented in graphs. The dependence of the resonant frequency of the filter from the value of the permittivity of the substrate is found. The effect of the type of metal (copper, gold, silver), from which made the SRR on the resonance frequency of the filter is defined. It is concluded that the increase in the value of the permittivity of the substrate causes a decrease in the value of the resonant frequency of the filter. While the type of metal material of the SRR, on the resonance filter properties do not have a significant influence. The research results will reduce the time spent on the design and optimization of the design parameters.

Abstract: The electro-optical coefficients r₂₂, r_е of doped lithium niobate crystals were determined by the interference-polarization method, depending on the zinc concentration in the range 0.018-0.88 wt. %. The dependence of the electro-optical coefficient on the zinc concentration is nonlinear. The values r₂₂, r_е are determined.

Abstract: In this paper is considered the autocorrelator of ultrashort pulses based a Michelson interferometer, his schemes and operating principles. The method of measuring ultrashort pulses is given. The schemes and principles of operation of the main nodes of the autocorrelation receiver are presented: the optical-mechanical part (the construction of the Michelson interferometer) and the electronic part, which includes a photodetector module, a control and data processing unit with a speaker amplifier, and a personal computer.

Abstract: The luminescent sensory systems based on manganese-doped zinc sulfide quantum dots were developed for aqueous environment monitoring. The structural, optical and sensory characteristics of quantum dots were investigated. The mechanism of ZnS:Mn²⁺ interaction with methane in the aqueous media, as well as factors that have a primary influence on the formation of the sensory response in the reaction with methane, were determined.