The Crystallography of Interphase Boundaries Between Silicon Carbide and Silicon Nitride in Silicon Nitride—Silicon Carbide Particulate Composites

Interphase boundaries between 3C SiC grains and two different -Si₃N₄ morphologies in Si₃N₄–SiC composites have been studied by transmission electron microscopy. In general, boundaries between small -Si₃N₄ intragranular precipitates and surrounding SiC grains were relatively free of intergranular films, whereas boundaries between large -Si₃N₄ grains and adjacent SiC grains were invariably covered with thin intergranular films. Orientation relationships approximating to [110] 3C SiC [0001] -Si₃N₄ and (001) 3C SiC (10 0) -Si₃N₄ were found to dominate between 3C SiC grains and the intragranular -Si₃N₄ precipitates, but there was no evidence of any favoured orientation relationship between the large -Si₃N₄ grains and adjacent SiC grains. The rationale for special orientation relationships arising when there is no intergranular film present at 3C SiC–-Si₃N₄ interfaces is explored geometrically using the near-coincidence site lattice model, with the significant result that the dominant orientation relationships between 3C SiC grains and the intragranular -Si₃N₄ precipitates have low misfits relative to all other possible orientation relationships between 3C SiC and -Si₃N₄.     

Synthesis and Stabilization of Fe–Nd–B Nanoparticles for Biomedical Applications

Stable composition of Iron Neodymium Boron nanoparticles are formed by a chemical method. Conventional borohydride reduction method was used. The particles are in the size range of 30–100 nm. Silica coating was applied to stabilize and prepare the particles for in vitro applications such as cell separation and diagnostics. Morphology of particles has been studied along with the structure and magnetic properties.     

Optimization of Energy Scope for Titanium Nitride Films Grown by Ion Beam-Assisted Deposition

The deposited energy during film growth with ion bombardment, correlated to the atomic displacement on the surface monolayer and the underlying bulk, has been calculated by a simplified ion-solid interaction model under binary collision approximation. The separated damage energies caused by Ar ion, different for the surface and the bulk, have been determined under the standard collision cross section and a well-defined surface and bulk atom displacement threshold energy of titanium nitride （TIN）. The optimum energy scope shows that the incident energy of At＋ around 110eV for TiN （111） and 80eV for TiN （200） effectively enhances the mobility of adatom on surface but excludes the damage in underlying bulk. The theoretical prediction and the experimental result are in good agreement in low energy ion beam-assisted deposition.     

Production of Silicon and Chlorine Ion Beams

We did some preliminary tests on LECR3 to produce Silicon and Chlorine ion beams in October 2003. Some good results have been achieved. Some useful conclusions have been drawn from those experiments. And afterwards, we also provided the HIRFL accelerator with the ^35Cl^12 ion beam for the nuclear physics experiments.     

Photoluminescence Characterization of Silicon Nanoparticles Hybridized Europium Complex

A europium complex Eu (DBM)3 TPPO (Eu tris(benzoylmethide)-(triphenylphosphine oxide)) and silicon nanoparticles have been hybridized.The hybridization can evidently change the photoluminescence (PL) characteristics of the Eu complex in the following aspects:under an excitation of 390nm,the intensity of the PL peak at 611nm due to the ^5Du-^7F2 transition of the Eu^3 ions has been increased by 30%,and thc integrated PL intensity in the visible range has been increased by nearly 3 times;the PL excitation efficiency beyond 440nm has been improved cvidently;the peak in the PL excitation spectrum shifts from 408nm to 388nm,and the PL decay time decreases from 2.07 to 0.96μs,The experimental results indicatde that in the PL process,the photoexcited energy may transfer from the silicon nanoparticlcs to the Eu^3 ions.     

Ion Cleaning of Facets for Improving the Reliability of High Power 980 nm Semiconductor Lasers

We report a simple and available way of improving the reliability of high power InGaAs 980 nm lasers by cleaning the facets using Ar ion before the protecting films have been coated. The Ar cleaning can remove the impurity and the oxide on the air-cleaved facets of laser diodes. It is proven that the way has marked effect on reducing the gradual degradation rate of laser diodes and improving the catastrophic-optical-damage threshold.     

Microwave-Assisted Synthesis of Core–Shell Nanoparticles—Insights into the Growth of Different Geometries

Microwave irradiation is utilized for the rapid synthesis of gold–silver core–shell bimetallic nanoparticles (NPs) in a two-step process. A strategy of establishing a bilayer organic barrier around the core using citrate and ascorbic acid as capping agents, providing a means to achieve a well-defined boundary layer between the core and the shell material, is reported. These boundary layers are essential for synthesizing different core–shell morphologies and the approach results in tunable bimetallic NPs with defined core–shell structures, both for spherical as well as for triangular seed cores. In addition, theoretical calculations of the plasmonic characteristics based on the boundary element method of different classes of NPs are conducted. These investigations enable conclusions to be drawn on the influence of the core morphology on the tunability of their localized surface plasmon resonances.     

Enhanced Photoluminescence Intensity of Silicon–Germanium Nanoparticles: Silica Thin Films by Annealing in Forming Gas

Silicon–germanium nanoparticles are prepared by ion implantation and annealing method. Further annealing treatment is carried out in forming gas to passivate nonradiative defects around nanoparticles. Time-resolved photoluminescence measurements were examined to reveal the local environment surrounding the nanoparticles. With the increase in oxygen gas content, photoluminescence intensity from specimen is enhanced by ～5 times and its decay time τ decreases from 23.2 to 1.6 µs. Oxygen gas is considered to be an effective passivating gas for this kind of specimen.     

Design and Evaluation of Dynamic Replication Strategies for a High—Performance Data Grid

Physics experiments that generate large amounts of data need to be able to share it with researchers around the world .High performance grids facilitate the distribution of such data to geographically remote places.Dynamic replication can be used as a technique to reduce bandwidth consumption and access latency in accessuing these huge amounts of data.We describe a simulation framework that we have developed to model a grid scenario,which enables comparative studies of alternative dynamic replication strategies.We present preliminary results obtained with this simulator,in which we evaluate the performance of six different replication strategies for three different kinds of access patterns.The simulation results show that the best strategy has significant savings in latency and bandwidth consumption if the access patterns contain a moderate amount of gerographical locality.     

Silicon–germanium nanostructures for on-chip optical interconnects

Silicon–germanium epitaxially grown on silicon in the form of two-dimensional (quantum wells) and three-dimensional (quantum dots) nanostructures exhibits photoluminescence and electroluminescence in the technologically important spectral range of 1.3–1.6 μm. Until recently, the major roadblocks for practical applications of these devices were strong thermal quenching of the luminescence quantum efficiency, and a long carrier radiative lifetime. This paper summarizes recent progress in the understanding of carrier recombination in Si/SiGe nanostructures and presents a potential new route toward CMOS compatible light emitters for on-chip optical interconnects.     

Performance and Mechanism of Epoxy Resin for Reinforcement of Styrene–Butadiene Rubber

Styrene–butadiene rubber (SBR) vulcanizates reinforced by epoxy resin (EP) have been synthesized by an in-situ vulcanization and curing process. The influences of synthetic parameters, such as the contents of EP, carbon black, and types of compatilizers, on the microstructures, vulcanization, and mechanical properties of SBR have been investigated. It was found that EP in SBR exists in the form of a fibrillar interpenetrating network, which is important for the enhancement of mechanical properties of SBR. The experimental results showed that when the percentage of EP was in the range of 10–20%, the composite materials had the best comprehensive performance. In comparison with pure SBR, the tear strength and the tensile stress at 300% elongation of SBR-EP composite were increased significantly. The method can be applicable for other rubber vulcanizates to improve their mechanical properties.     

Dielectric Properties of Lithium–Titanium Ferrite Ceramics

The temperature dependences of the real and imaginary parts of the complex dielectric permittivities of ceramic Li–Ti ferrospinel are measured within the frequency range 10²–10⁶ Hz. The empirical expressions describing these dependences are derived and the frequency-independent electrophysical parameters of the material under study are obtained. The best agreement between the experimental and calculation data is achieved when the time constant and the static dielectric permittivity are decreasing functions of frequency. A model of relaxational processes accounting for this result is proposed. A certain role in polarization of the relaxation agents, whose reorientation is controlled by tunneling electron transitions inside the two-valence iron ion – three-valence metal ion, is assumed. It is stated that under certain conditions, the relaxation agent reorientation is likely to possess a collective character. The temperature dependences and are derived for a number of dc currents at different electric field strengths. Sharp variations in the dielectric characteristics of the ceramics are found.     

Influence of Some Parameters on the Synthesis of ZrO2 Nanoparticles by Heating of Alcohol–aqueous Salt Solutions

Parameters that influence ZrO₂ (3-mol% Y₂O₃ stabilized) nanoparticles prepared by heating of alcohol–aqueous salt solutions were investigated. It revealed that the kind of alcohol used significantly affected the particle size and morphology of the as synthesized nano-ZrO₂ powders. The ratio of alcohol to water (R/H) was also important to conduct the gelation process. The dispersion and sintering behavior of the powder could be optimized via aging. By carefully controlling the process, weakly agglomerated ZrO₂ nanoparticles with an average particle size of 13-nm (TEM) were achieved. The classical DLVO theory was employed to clarify the effect of solvent on powder morphology, an aging mechanism was proposed as well.     

Performance evaluation of numerical methods for the Maxwell–Liouville–von Neumann equations

The Maxwell–Liouville–von Neumann (MLN) equations are a valuable tool in nonlinear optics in general and to model quantum cascade lasers in particular. Several numerical methods to solve these equations with different accuracy and computational complexity have been proposed in related literature. We present an open-source framework for solving the MLN equations and parallel implementations of three numerical methods using OpenMP. The performance measurements demonstrate the efficiency of the parallelization.     

Control of Properties of Diamond-Like Silicon–Carbon Films

Physics of the Solid State - The possibilities of control of the electrophysical and mechanical properties of amorphous diamond-like silicon-carbon films by means of structural, chemical and...     

Tunable Synthesis of Sub-20 nm Gold Nanoparticles Capping with Cyclodextrin for Host–Guest Molecular Recognition on Nano-Surface

Gold nanoparticles capping with three types of natural cyclodextrins are synthesized, allowing for precise control over their sizes ranging from 9 to 20 nm. These nanoparticles exhibit remarkable colloidal stability during long-term storage, as well as excellent tolerance to saline, acidic, and alkaline conditions. Importantly, the assembly of nanoparticles is performed by using the silica nanospheres functionalized with cinnamyl group and the gold nanoparticle capping with three types of cyclodextrin, highlighting the selective formation of core-satellite superstructure based on the host–guest molecular recognition on nano-surface between different nanoparticles.     

Electrical Explosion of Wires for Manufacturing Bimetallic Antibacterial Ti–Ag and Fe–Ag Nanoparticles

Russian Physics Journal - Using a simultaneous electrical explosion of two twisted wires, bimetallic Ti–Ag and Fe–Ag nanoparticles are synthesized, where the component ratios are...