Single phase strontium ferromolybdate nanopowder with a double perovskite structure has been synthesized using the citrate gel technique at pH = 4. A superstructural ordering degree of the iron and molybdenum cations of 88% has been obtained. X−ray diffraction of pressed Sr2FeMoO6−δ pellets subjected to annealing at T = 700 K and p(O2) = 10 Pa has revealed the formation of the SrMoO4 phase at grain boundaries. The temperature dependence of the electrical resistivity in the 4.2 to 300 K range changes from a metal type one in the single phase Sr2FeMoO6−δ to a semiconductor type one in the Sr2FeMoO6−δ – SrMoO4 – Sr2FeMoO6−δ structure containing dielectric interlayers, indicating variable charge hopping in the latter structure. In the applied magnetic fields the temperature dependence does not change qualitatively; however, the resistivity decreases with increasing field, i.e., a negative magnetoresistance of up to 41% at T = 10 K and B = 8 T is observed. The external field forms a collinear spin structure, thus increasing the spin−polarized current through the barriers in the granular Sr2FeMoO6−δ – SrMoO4 – Sr2FeMoO6−δ heterostructure.

A review of the current state of the GaAs market as well as the state and the prospects of the Russian market have been provided. A brief analysis of the current state of RF−devices has been given The dynamics of world GaAs production and prices for the recent years have been reported. Methods of single crystal GaAs growth and tendencies of growth technology development have been described. The market of GaAs substrates, as expected, will amount to 3.6 million sq. inches and $650 million by 2017. Despite the high financial performance of the gallium arsenide market, the physical indicators of the world single− crystal GaAs market will remain rather small compared to worldwide figures, i.e. ~ 800 t/year by 2020. At the moment, the world market of GaAs single crystals and wafers exhibits a comparatively small volume, high concentration of production capacities in China and the presence of major players capable to endure adverse conditions. Russian market of special semiconductor materials (GaAs, etc.) has a volume that is small compared to worldwide figures. However, there is an understanding that the implementation of import substitution programs and the development of advanced electronic component base in Russia require the fabrication facilities for high purity compounds and initial components. Since 2015 GaAs plate production projects have emerged under the auspices of Roselektronika.

Copper selenide is a promising material for power generation in medium−temperature range 600—1000 K. A number of features of the Cu—Se system, i.e. the existence of a phase transition in Cu2Se compound, the high speed of Cu ion diffusion and the high vapor pressure of Se at high temperatures, necessitate massive experimental investigations aimed to develop and optimize a method for obtaining a copper selenide base bulk material. In this work the effect of mechanochemical synthesis mode and subsequent compaction method on the thermoelectric properties and structure of copper selenide were studied. The source material was obtained by mechanochemical synthesis. The hot pressing and spark plasma sintering methods were used for obtaining the bulk samples. The structure and phase composition were studied by X−ray diffraction and scanning electron microscopy. We show that increasing the time of mechanochemical synthesis to 5 hours leads to copper depletion of the powders and the formation of nonstoichiometric phase Cu1,83Se which persists after spark plasma sintering. Comparison of the structure and properties of the material obtained by spark plasma sintering and hot pressing showed that the material obtained by hot pressing has a greater degree of the grain defects. The highest thermoelectric efficiency ZT = 1.8 at 600 °C was observed in the material obtained by spark plasma sintering. We show that the main factor affecting the value of the thermoelectric efficiency ZT of the studied materials is the low thermal conductivity. The difference in thethermal conductivities of the materials obtained by different methods is attributed to the electronic component of thermal conductivity.

Abstract. The anisotropy of the mechanical properties of single crystal ZrO2 — 2.8 mol.% Y2O3 solid solutions has been studied. The crystals have been grown by skull melting technique. The microhardness and fracture toughness have been tested for different crystallographic planes by indentation with different indenter diagonal orientations. The study shows that the microhardness of the material depends on the crystallographic orientation but slightly whereas the fracture toughness varies for different planes. The maximum fracture toughness has been observed in the crystal specimen cut laterally to the <100> orientation. We have studied the anisotropy of the microhardness in the material for different indenter diagonal orientations. The maximum fracture toughness has been obtained for the {100} plane and the <100> indenter diagonal orientation. The phase composition inside and outside the indents on the {100}, {110} and {111} surfaces for 20, 3 and 1 N loads has been studied in local areas using Raman spectroscopy. The degree of the tetragonal−monoclinic transition has been evaluated for different crystallographic planes and different indenter diagonal orientations. The tetragonal−monoclinic transition proves to be anisotropic, and this affects the transformation hardening mechanism. The maximum amount of the monoclinic phase is present in the vicinity of the indent in the {100} plane for the <100> indenter diagonal orientation. The highest fraction toughness has also been observed in the {100} plane for the <100> indenter diagonal orientation. Probably, the abovementioned indenter diagonal orientation provides for the maximum stress concentration along the coherent conjugation planes between the tetragonal and the monoclinic phases during the tetragonal−monoclinic transition, i.e. (100)t||(100)m and [001]t||[010]m.

Results of developing a system of models and algorithms for parameter calculation in micro and nanoelectronics materials processes and equipment design have been considered. A distinctive feature of the teaching methods for special technological courses on electronics materials is that the courses are designed by analogy with electronics materials technologies: from a bulk single crystal to device structures the typical dimensions of which are within several
tens of nanometers. A scientific model approach to the solution of technological problems has been developed during the study of heat and mass transfer processes which, along with the interaction processes in liquids and gas and with account of the heterogeneous reactions, are the theoretical basis of the electronics materials technology. The possibilities of physical and mathematical modeling have been compared. Approaches to the creation of mathematical models for the single crystals growth processes of semiconductors, epitaxial layers and heterostructures have been considered and their possible practical applications have been outlined. We show that the ideas put forward by V.V. Krapukhin at early stages of training specialists in electronics materials technology and further developed by his students have formed the basis for the training of several generations of highly skilled specialists

The problem of choosing the architecture of buffer layers is considered. This is typical problem faced when standard models of different heterostructures with a controlled level of mechanical stresses and low defect density in the bulk and at the layer boundaries are developed. It has been shown that the abovementioned characteristics depend on the quality of the initial substrate surface. They are also dependent on the substrate preparation procedure for epitaxy and the composition of the buffer layers. We note that the quality of the substrate surface is most objectively estimated from the bonding strength of the spliced plates. It has been also shown that if the bonding strength is below 107 Pa (this is the most frequent experimental value), the substrate surface is characterized by noticeable roughness. There are different contaminating elements and chemical compounds, clusters and dust particles, structural defects of different dimensionality on the substrate surface. In addition the substrate surface is restructured so that the «broken» bonds are brought closer to each other. The effect of the real substrate surface structure and the compatibility of the materials on the quality of the epitaxial film has been demonstrated. The analysis provided in this work shows the feasibility of growing a preliminary low−temperature (LT) underlying layer on the substrate for small lattice mismatch. Additional transition layers with changing component ratios in the composition or in the form of superlattices are required for largely differing lattice parameters.

Results of nanoscale study (by atomic force microscopy and X−ray diffraction) of single−, two− and three−layered Cr, Cu, Al and Ni metallic nanofilms formed on a ceramic sital substrate on MVU TM−Magna T magnetron equipment (NIITM, Zelenograd) have been reported. The growth rates and the structure of the nanofilms were determined while varying of power/current ratio from 200/0.7 to 800/2 Wt/A and magnetron sputtering time from 30 to 360s at an operating pressure of 0.5 Pa Ar. The criterion for optimization quality based on the minimum roughness was as follows: Ra = min{Rai} and/or Rq → min{Rqi} (i is the number of varies modes used). The mean roughness Ra and RRMS = Rq have been determined from the scan of the vertical profile (resolution 20 pm) of the atomic force microscopic image. We found that the nanofilm–forming nanocluster structure size for the modes when Ra and Rq were the smallest had a close–to–Gaussian grain size distribution. The film growth rates have been determined based on the atomic force images of the nanofilm structure in the form of either a single step or steps obtained at different time intervals. The mode and parameters of magnetron sputtering and the composition of the Cr, Cu, Al and Ni targets affect the size of clusters which form the surface of the metallic nanofilms. X−ray phase and structural analyses have been carried out in order to determine the texture and the change in the distances between the lattice planes. The correctness of the optimization criterion correlating the nanolayer deposition parameters and their quality has been corroborated by the coincidence of the magnetron sputtering modes which provided for the lowest roughness and the smallest average size of the X−ray coherence region as using the Debye− Scherrer equation.

This article presents a theoretical study of sensor activity of nanosystems based on carbon nanotubes modified with functional groups (carboxyl, aminogen, nitrogroup) for some metal atoms and ions. Calculations have been performed within the frameworks of a molecular cluster model with the use of the semiempirical MNDO method and the density functional theory DFT. The mechanism of functional group binding to the open border of single−walled zig− zag carbon nanotubes leading to the formation of chemically active sensors on their basis has been investigated. Main geometric and electron energy characteristics of the resultant systems have been defined. Interaction of the sensors so synthesized with atoms and ions of some metals, e.g. potassium, sodium and lithium, has been analyzed.

In indirect band gap semiconductors, for example, in silicon, the free carrier recombination lifetime is determined by recombination through deep level centers and inversely proportional to their concentration. This parameter is of the utmost importance for characterizing the quality of the material. Contactless methods of free carrier recombination lifetime measurements by protoconductivity decay analysis are most widely used. The measurement results are largely affected by surface recombination. The calculation of the lifetime in the bulk of a sample from the characteristic time of photoconductivity decay remains relevant since there is no ambiguous analytical solution of the continuity equation for this case. In this paper, an analysis of the relaxation of photoconductivity in single−crystal silicon wafers with non−passivated surfaces was carried out with numerical methods. The applicability of the well–known formulas for estimating the contribution of surface recombination to the effective photoconductivity decay time was discussed. We show that the time in which the «fast» exponents disappear depends on the relative thickness of the sample. It is only this part of the relaxation curve that the effective decay time is determined by the maximum value of the surface component of the relaxation time and is described by the well−known formulas. The saturation of the effective relaxation time at the point when the signal intensity reaches 45 % of the peak one (the onset point of effective decay time counting pursuant to the SEMI MF 1535 standard recommendation) only occurs in samples with thicknesses less than 3—5 diffusion lengths. For thick samples the contribution of the «fast» exponentials to the effective photoconductivity relaxation time is observed up to 5 % of the peak signal (i.e., until the noise level of the measured signal is reached). Use of the recommended formulas, including for the «infinite recombination rate» case at which the maximum surface lifetime is d2/π2D, leads to a sufficiently large (up to 20 %) error in free carrier recombination lifetime calculation.