Congratulations to Valerii Viktorovich Mikheev

Anniversaries and Memorable Dates

Congratulations to Valerii Viktorovich Mikheev Candidate of Technical Sciences, honorable builder of the Russian Federation, and recipient of the prize awarded by the Council of Ministers of the USSR     

Sequence of phase transformations and inhomogeneous magnetic state in nanosized Sr<Subscript>2</Subscript>FeMoO<Subscript>6 – δ</Subscript>

We have studied the effect of synthesis conditions on the phase composition, grain size and morphology, degree of superstructural ordering, and magnetic properties of the Sr₂FeMoO_6–δ double perovskite. The results demonstrate that its magnetic state, dependent on the nonuniformity of grain morphology and the degree of superstructural ordering of the iron and molybdenum cations, correlates with the initial solution pH. Analysis of the sequence of phase transformations during strontium ferromolybdate crystallization in the citrate gel process from a pH 4 starting solution allowed us to propose combined conditions that ensure the preparation of single-phase Sr₂FeMoO_6–δ powder with an average grain size in the range 50–120 nm and the highest degree of superstructural ordering of the iron and molybdenum cations: P = 88%.     

Set Based Theoretical Approach to the Representation of Routing Stage in the Design Flow for the Heterogeneous FPGAs and Reconfigurable SoCs

Russian Microelectronics - The paper presents a mathematical apparatus based on the set-theoretic approach, which allows the prompt configuration of software routing within the design flow of user...     

Influence of the doping type and level on the morphology of porous Si formed by galvanic etching

The formation of porous silicon (por-Si) layers by the galvanic etching of single-crystal Si samples (doped with boron or phosphorus) in an HF/C₂H₅OH/H₂O₂ solution is investigated. The por-Si layers are analyzed by the capillary condensation of nitrogen and scanning electron microscopy (SEM). The dependences of the morphological characteristics of por-Si (pore diameter, specific surface area, pore volume, and thickness of the pore walls), which determine the por-Si combustion kinetics, on the dopant type and initial wafer resistivity are established.     

A self-heated hollow cathode made of compacted TiN powder: the preparation method and test results

A method for the formation of a tubular hollow self-heated cathode using magnetic-pulse pressing of a mixture of TiN (90%) and Ti (10%) powders with subsequent annealing and sintering during operation of the compact as a cathode in a high-current (5–45 А) discharge at temperatures of 2000–2200°C is described. Massive tubular cathodes with a 2.5-mm-thick wall and a large (up to 12 mm) inner diameter were manufactured. The erosion rate of a TiN cathode was 2.3 × 10^–7 g/C for the operation in an Ar/N₂ mixture and increased by a factor of 1.6 in the oxygen–argon plasma generation mode with separate feeding of gases.     

Radiation annealing of AMg6, 1441, and VD1 aluminum alloy strips using a ribbon source of accelerated ions

The results of our earlier studies are summed and new data are presented on the influence of beams of accelerated Ar⁺ ions on the mechanical properties and structure of various commercial aluminum alloys. A short-time (5–60 s) ion-beam processing of cold-deformed alloys is shown to lead to their softening, which is analogous to that upon intermediate annealing at 320–400°C for 2–3 h used in cold rolling. An experimental ribbon ion source, which is intended for in situ processing of rolled sheets in a rolling line to remove strain hardening instead of long-term furnace annealing, is described.     

Limiting sensitivity of photodetectors based on A3B5 photodiodes for middle infrared range

The noise of photodetectors based on mid-IR A³B⁵ photodiodes (PhDs) implemented in a transimpedance amplifier scheme is analyzed. Recommendations concerning the choice of amplifier elements depending on the dynamic resistance of PhDs are given. It is shown that, using modern low-noise amplifiers, it is possible to reach a potential limiting threshold sensitivity of photodetectors only using PhDs with dynamic resistances above 50 Ω.     

The problems of mass transfer and formation of deposits of corrosion products on fuel assemblies of a VVER-1200 reactor

On the basis of examination of materials published both in Russia and abroad, as well as their own investigations, the authors explain the reasons for the occurrence of such effects as AOA (Axial Offset Anomalies) and an increase in the coolant pressure difference in the core of nuclear reactors of the VVER type. To detect the occurrence of the AOA effect, the authors suggest using the specific activity of ⁵⁸Co in the coolant. In the VVER-1200 design the thermohydraulic regime for fuel assemblies in the first year of their service life involves slight boiling of the coolant in the upper part of the core, which may induce the occurrence of the AOA effect, intensification of corrosion of fuel claddings, and abnormal increase in deposition of corrosion products. Radiolysis of the water coolant in the boiling section (boiling in pores of deposits) may intensify not only general corrosion but also a localized (nodular) one. As a result of intensification of the corrosion processes and growth of deposits, deterioration of the radiation situation in the rooms of the primary circuit of a VVER-1200 reactor as compared to that at nuclear power plants equipped with reactors of the VVER-1000 type is possible. Recommendations for preventing the AOA effect at nuclear power plants with VVER-1200 reactors on the matter of the direction of further investigations are made.     

The synthesis of single phase WC nanoparticles/C composite by solid state reaction involving nitrogen-rich carbonized polyaniline

Single phase tungsten carbide nanoparticles (WC-NPs), (mean particle diameter 5.4 nm), distributed over carbonized polyaniline (C-PANI) nanotubes/nanosheets were synthesized by a solid state reaction between WO₃ and nitrogen-rich carbonized polyaniline at 1000 °C in a reducing atmosphere. The resulting composite was characterized by X-ray diffractometry, electron microscopy, thermogravimetry in oxidizing and reduction atmospheres and elemental analysis. We suggested that the synthesis of WC as a single phase was facilitated by reactive C atoms with dangling bonds, formed upon nitrogen removal.