Materials physics and mechanics

RAR RUS 1-10 Carnegie Mellon University Giri Anit K.

Pittsburgh, PA 15213-3890, USA

Carnegie Mellon University Pittsburgh Chowdary Krishna M.

PA 15213-3890, USA

Carnegie Mellon University Majetich Sara A. AC Magnetic Properties of Compacted FeCo Nanocomposites Here we report the AC magnetic properties of soft magnetic nanocomposites made from compaction of Fe10Co90 nanoparticles. Following a discussion of previous work on soft magnetic nanocomposites, the sample preparation and experimental characterization by AC permeametry are described. The permeability is constant and equal to the DC value for low frequencies, but drops off sharply above a characteristic frequency fc. A model is developed to explore the relation between fc and material parameters including the effective anisotropy, exchange coupled volume, temperature, and saturation magnetization. Magnetic Properties Nanocomposites https://mpm.spbstu.ru/article/2000.1.1/ 2000_1_1_p1.pdf

RAR RUS 11-14 National University of Singapore Zhang J. National University of Singapore Chow G.M.

Singapore

Naval Research Laboratory Lawrence S.H.

Washington, DC 20375, USA

Naval Research Laboratory Feng G.M.

Washington, DC 20375, USA

Nanostructured Ni Films by Polyol Electroless Deposition Nanostructured Ni films were deposited on Cu by reducing nickel acetate tetrahydrate in refluxing ethylene glycol at about 194 °C. The effects of deposition time (t) and Pt as nucleating aid were investigated in this polyol process. The solution chemistry varied with t. At longer t, corrosive attack of the solvent on deposited films led to dissolution and re-deposition of Ni. Saturation magnetization increased with t and decreased with increasing Pt precursors. The deposited Ni films were magnetically saturated. They showed in-plane magnetization anisotropy and perpendicular coercivity anisotropy. The use of Pt caused rapid powder precipitation but did not enhance film deposition. The Pt-catalyzed Ni films showed a (200) texture and a higher squareness ratio. Nanostructured Films Polyol Electroless Deposition https://mpm.spbstu.ru/article/2000.1.2/ 2000_1_1_p2.pdf

RAR RUS 15-19 Institute for Analytical Instrumentation RAS Cirlin G.E.

St.Petersburg, Russia

Institute for Analytical Instrumentation RAS Polyakov N.K.

St. Petersburg, Russia

Institute for Analytical Instrumentation RAS Petrov V.N.

St.Petersburg, Russia

Institute for Analytical Instrumentation RAS V.A. Egorov V.A.

St.Petersburg, Russia

Ioffe Institute Denisov D.V.

St.Petersburg, Russia

Ioffe Institute Volovik B.V.

St.Petersburg, Russia

Ioffe Institute Ustinov V.M.

St.Petersburg, Russia

Alferov Zh.I. Ioffe Institute Ledentsov N.N.

St.Petersburg, Russia

Technical University Heitz R.

Berlin, Germany

Technical University Bimberg D.

Berlin, Germany

Max-Plank-Institute for Microstructure Physics Zakharov N.D.

Halle/Saale, Germany

Max-Plank-Institute for Microstructure Physics Werner P.

Halle/Saale, Germany

Max-Plank-Institute for Microstructure Physics Gösele U.

Halle/Saale, Germany

Heteroepitaxial Growth of InAs on Si: the New Type of Quantum Dots Under certain growth conditions InAs/Si heteroepitaxial growth proceeds via Stranski-Krastanow or Volmer-Weber growth modes depending on the growth parameters. The critical thickness at which three dimensional InAs islands start to appear at the Si(100) surface is within the range of 0.7-4.0 monolayers (substrate temperature range is 350 °C - 430 °C). Their size depends critically on the growth conditions and is between 5 nm and 80 nm (uncapped islands). Critical lateral size of the coherent (Si capped) dislocation-free island is equal to 2−5 nm depending on the island height. Islands having larger size are dislocated. Optical properties of InAs nanoscale islands capped with Si reveal a luminescence band in the 1.3 µm region. Heteroepitaxial Growth Quantum Dots Semiconductors https://mpm.spbstu.ru/article/2000.1.3/ 2000_1_1_p3.pdf

RAR RUS 20-26 Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FO.R.T.H.) Kiriakidis G.

Heraklion, Greece

Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FO.R.T.H.) Katsarakis N.

Heraklion, Greece

Fabrication of 2-D and 3-D Photonic Band-Gap Crystals in the GHz and THz Regions Two- and three-dimensiona1 dielectric and metallic structures exhibiting photonic band-gaps in a broad frequency range were fabricated by deep X-ray lithography and laser micro-machining. These techniques seem promising for mass production of photonic structures with full band-gaps in a spectrum ranging from the millimeter wave up to the far infrared regime. Deep X-ray lithography was applied to produce periodic 3-D photonic band-gap structures based on the “three-cylinder” model with mid-gap frequencies up to 2.4 THz. Metallic 3-D structures with incorporated point and linear defects are currently under development. Layered metallic and metallo-dielectric structures exhibiting a cutoff frequency in the microwave regime were fabricated by laser precision machining. The observed cutoff frequency can be easily tuned by varying the interlayer distance or the filling fraction of the metal. Combinations of layers with different metal filling fractions create defect modes with relatively sharp peaks, which are also tunable. The metallo-dielectric structures are significantly smaller than the simple metallic ones. The experimental measurements seem to be in good agreement with theoretical calculations. Band-Gap Crystals Dielectric structures Metallic structures https://mpm.spbstu.ru/article/2000.1.4/ 2000_1_1_p4.pdf

RAR RUS 28-30 P-4505-2016 7006034020 0000-0002-2973-8645 Institute of Problems of Mechanical Engineering RAS Kukushkin S.A. sergey,a.kukushkin@gmail.com

St.Petersburg, Russia

Institute of Problems of Mechanical Engineering RAS Nemenat S.V.

St.Petersburg, Russia

A Mathematical Model Of Metal Films Deposition from Photoactive Compound Solutions on Solid-Liquid Interface The kinetics of the growth of thin metal films from solutions of photoactive chemical coordination compounds irradiated by light at a certain wavelength has been theoretically investigated. In the framework of our mathematical model the time dependencies of the basic characteristics of the film growth process (size distribution function, density of nucleation, concentration of metal on the surface) have been computed. They proved to be in accordance with the experimental data. It is shown that the flux of metal (substance) from the solution onto the surface of the substrate can be derived from the stationary diffusion equation with the added term taking into account the influence of the photochemical substance source. It may be inferred that the variation of light intensity, in great range, keeps the kinetics of the process of film deposition out of the drastic changes. Metal films deposition; Modeling of the film growth process https://mpm.spbstu.ru/article/2000.1.5/ 2000_1_1_p5.pdf

RAR RUS 31-38 Naval Research Laboratory Masumura R.A.

USA

Institute of Problems of Mechanical Engineering RAS I.A. Ovid’ko И.А.

St.Petersburg, Russia

Enchanced Diffusion near Amorphous Grain Boundaries in Nanocrystalline and Polycrystalline Solids A theoretical model is constructed that describes diffusion processes enhanced by the elastic interaction of the diffusing species and amorphous grain boundaries in nanocrystalline and polycrystalline solids. A partial differential equation governing evolution of the spatially inhomogeneous concentration of the diffusing species near amorphous grain boundaries is numerically solved. It is shown that the enhanced diffusion essentially influences the growth of amorphous grain boundaries in solids under irradiation and thermal treatment as well in sintered ceramics and is capable of contributing to the anomalously fast diffusion in nanocrystalline solids. Amorphous Grain Boundaries; Nanocrystalline Solids; Polycrystalline Solids https://mpm.spbstu.ru/article/2000.1.6/ 2000_1_1_p6.pdf

RAR RUS 39-44 Ioffe Institute Orlova T.S.

St.Petersburg, Russia

Laboratoire de Physique du Solide, CNRS ESPCI Laval J.Y.

Paris, France

Ioffe Institute Smirnov B.I.

St.Petersburg, Russia

Correlation between Superconducting Transport Properties and Grain Boundary Microstructure in High-Tc Superconducting Ceramics The superconducting transport properties (I–V, Ic –B and Ic –T) were correlated with a systematic characterization of the grain boundary microstructure, via TEM observation and local chemical analysis in STEM by EDX on YBa2 Cu3-xOy (D samples), YBa2 Cu3-xOy /Agx (S samples) and DyBa2 Cu3-xOy /1wt% Pt (0≤x≤0.4) ceramics. It was shown that in all samples studied the critical current I c is controlled by weak links at grain boundaries. The measurements of I c (T) indicated that in copper-deficient yttrium ceramics, Ag-doping leads to change of weak link character from superconductor-insulator-superconductor (SIS) to superconductor-normal metal-superconductor (SNS) type. This SNS behaviour seems to be a result of percolation path of supercurrent through clean boundaries with extremely narrow range (≅1 nm) of Ag segregation on them. Specific Ag precipitates of 2-5 nm size on or near clean boundaries were found in S samples for x=0.4. This is most likely to be a reason for the improvement of I c in these samples by a factor of 3. In copper-deficient dysprosium ceramics doped with Pt, Pt-doping leads to a substantial increase in Ic and pronounced ‘fish-tail’ effect in magnetic field at T≤77 K in non-stoichiometric composition with x=0.2. Better behaviour of I c in magnetic fields in these samples may be associated with the substantial increase in the proportion of clean boundaries and decrease in twin spacing. Superconducting Transport Properties; Grain Boundary Microstructure; High-Tc Superconducting Ceramics https://mpm.spbstu.ru/article/2000.1.7/ 2000_1_1_p7.pdf

RAR RUS 45-48 Electrotechnical University Vendik O.G.

St.Petersburg, Russia

Electrotechnical University Zubko S.P.

St.Petersburg, Russia

Modeling of Size Effect on Dielectric Response of Thin Ferroelectric Films The size effect in thin film sandwich structures is considered. Three types of boundary conditions for dynamic polarization at interface electrode-ferroelectric layer are formulated. The type of boundary conditions depends on matching crystal lattices of electrodes and ferroelectric layer. A model describing the dependence of dielectric permittivity on biasing field, temperature, and thickness of the thin ferroelectric film is proposed. The results of the simulation are in good agreement with experiments. Modeling of Size Effect; Ferroelectric Films https://mpm.spbstu.ru/article/2000.1.8/ 2000_1_1_p8.pdf

RAR RUS 49-53 P-4505-2016 7006034020 0000-0002-2973-8645 Institute of Problems of Mechanical Engineering RAS Kukushkin S.A. sergey,a.kukushkin@gmail.com

St.Petersburg, Russia

Institute of Problems of Mechanical Engineering RAS Osipov A.V.

St.Petersburg, Russia

Institute of Problems of Mechanical Engineering RAS I.A. Ovid’ko И.А.

St.Petersburg, Russia

Critical Current Density in Polycrystalline High-Tc Superconductors with Disordered Tilt Boundaries A theoretical model is suggested which describes the effect of tilt boundaries with chaotically arranged dislocations on the critical current density in high-transition-temperature (Tc ) superconductors. Stress fields of such boundaries, that suppress high-Tc superconductivity, are revealed to be long-range as compared to those of tilt boundaries with periodically ordered grain boundary dislocations. With this factor taken into consideration, the dependence of the critical current density accross tilt boundaries on boundary misorientation θ is calculated and compared with the experimental data. Critical Current Density; High-Tc Superconductors https://mpm.spbstu.ru/article/2000.1.9/ 2000_1_1_p9.pdf

RAR RUS 54-59 Freiberg University of Mining and Technology Seefeldt M.

Freiberg, Germany

TEM and STM Investigations on the Disclination Nature of Fragment Boundary Triple Junctions After a short review of recent TEM measurements to characterize partial disclinations in fragment boundary triple junctions in cold-rolled copper, STM results from the same specimens are presented which support a disclination interpretation of the observed fragment structure. The role of the fragment boundary mosaic or of the corresponding immobile partial disclination network in work-hardening is discussed. Although the orientational mismatches around the fragment boundary triple junctions are only small, the disclination contribution dominates work-hardening behaviour at large strains. Disclination Nature; Fragment Boundary Triple Junctions https://mpm.spbstu.ru/article/2000.1.10/ 2000_1_1_p10.pdf