In following are presented the characterization results of nanostructured hybrid composites using alumina matrix reinforced with nanostructured particles of Ni, Ti and soot. The soot used in this work is the byproduct from the synthesis of Carbon Nanotubes (CNT) or fullerene and contains traces (>1wt%) of either CNT or fullerene. Ni and Ti are used in this work for their inherent catalytic ability for heterogeneous nucleation of carbon nanostructures (nanotubes, fullerenes). The hybrid composites are produced by a combination of methods including mechanical milling, sonication, and Spark Plasma Sintering (SPS). Mechanical milling is conducted in high energy mills, the milled and as manufactured powders are sonicated to assure their dispersion, homogeneity and promote percolation of the components during sintering. Mechanical milling and SPS have positive effects to promote the synthesis of different carbon nanoparticles. For instance, it is observed that mechanical milling of fullerene soot sponsors the synthesis of nanostructured diamond particles and using SPS can be synthesized diamond too and fullerene. Although, it is important to notice that SPS conditions are critical to the amount and type of synthesized particles. The use of CNT soot sponsors porosity, hence lower density resulting in an ideal material for membrane and porous media applications. The results of characterization (X-Ray diffraction, electron microscopy (scanning and transmission)) and the mechanical properties (Vickers microhardness) are discussed accordingly.

The electrochemical studies of the corrosion can provide indirect techniques that they can determinate the corrosion rate of metals or alloys immersed in a corrosive medium. For many years, most studies about the cathodic and anodic polarization behaviour of metals have been confined to traditional steady-state techniques, such as potentiodynamic sweep measurements. However, steady-state techniques are limited because they give information only on the rate-determining step. Moreover, during the measuring process, technique such as potentiodynamic sweep polarize the electrode surface to such a great extent, in order to uncover corrosion mechanism, that the validity of the results can be questioned particularly in the cases when protective films. Transient electrochemical techniques such as Electrochemical Noise (EN), are less intrusive because they can provide information about the processes without disturbing the reactions with the voltage application.

Hydrogenated nanocrystalline silicon (nc-Si:H), a mixture of nanometer sized crystallites and amorphous silicon tissue, demonstrates a photoluminescence band centered at ∼ 0.7 eV, which emerges in response to annealing at an onset temperature of ∼ 200–300 °C. This temperature range correlates well with hydrogen effusion spectroscopy studies, and evidence suggests thermal liberation of hydrogen from grain boundary regions allows oxidation of crystallite surfaces during annealing. We tentatively attribute the 0.7 eV PL in nc-Si:H to deep donor defect states related to oxygen precipitates, and argue for the possible involvement of dislocations inside of crystallites to accompany these precipitates.

Infrared absorption spectroscopy is a powerful tool for structural and functional studies of biomolecules. The technique enables direct access to the vibrational fingerprints of molecular bonds in the mid-infrared spectral region (3-20μm). Although intrinsic absorption cross-sections are nearly ten orders of magnitude greater than corresponding Raman cross-sections, they are still small in comparison with those of fluorescent molecules. Sensitivity improvements are therefore required for the method to be applicable to single molecule / molecular layer studies. In this work, we demonstrate the use of lithographically patterned arrays of nanoantennas to enhance the absorption signature of the protein amide-I and II backbone vibrations. Strong absorption signals from monolayer thickness films are obtained. By arranging ensembles of tailored antennas in specific lattices, higher quality factor resonances and increased near-field intensities are possible. These features are leveraged to obtain 104-105 fold signal enhancements and the direct measurement of vibrational spectra of proteins at zepto-mole sensitivity levels.

The focus of this work is wafer retaining rings and their impact on chemical mechanical planarization (CMP) process stability, yield, and overall cost of ownership (CoO). The study looks at various CMP retaining ring materials and processing methods. Tribological investigations as well as wafer processing are critical to understand the retaining ring and polishing pad environment. Interactions at the ring/pad interface have a major effect on the planarization and defectivity of a polished wafer. Shear and normal forces at this interface, as well as temperature and lubrication regimes, were monitored to establish an empirical model. All process conditions equal, the material properties of retaining rings govern the coefficient of friction (COF) in the ring and pad contact area. Present study demonstrates a lower COF to be an indicator of extended ring lifetime, decreasing WTWNU and removal rate (RR) variation. The study correlates the findings on wafer level data from high volume manufacturing fabs with empirical data generated using applications lab tribological equipment to understand the on-wafer performance as a function of retaining ring material. The study's further aim is to understand for specific applications, the material interactions on-wafer using various retaining ring materials. CMP process optimization can be attained with a better understanding of retaining ring design and material characteristics, as well as polishing head and slurry parameters.

In nanotechnology, many scientists have been seeking for new functional polymers, which can replica nano-sized features to achieve improved performances of nano-devices. Soft lithography has been widely used in replica of small features as a low cost alternative to conventional UV photolithography. However, commercial silicon rubbers, PDMS polymers, which have been used in current soft lithography, show limitations, especially for nano-resolution soft lithography. These limitations have motivated us to develop a new version of PDMS polymers to overcome those limitations and thus to extend current technology in soft lithography to the advanced level. Since the resolution of soft lithography significantly relies on stamping performance, we designed a novel PDMS prepolymer, which has photocurable cross-linkers to enhance mechanical property to improve lithographic performance and also to create photocurable capability.

A kinetic Monte Carlo (kMC) model for the simulation of the coarsening of nanoporous metals is developed and demonstrated. The model treats surface evolution through the mechanism of surface diffusion by following atoms hopping between sites on an FCC lattice. Using a generic model for event energy barriers, we are able to demonstrate trends in the simulation and show that at high temperatures, coarsening follows approximately the scaling law predicted by continuum surface diffusion theory; the behavior is less clear at low temperatures. By selecting event energies to model palladium we show that we are able to reach temperatures and time scales that have relevance to experiments and applications.

The MARS (Multi-Analyses on Radioactive Samples) beamline, at Synchrotron Soleil (France) is fully dedicated to advanced structural and chemical characterizations of radioactive matter (solid or liquid), coupling analytical tools such as X-ray absorption spectroscopy, X-ray diffraction, X-ray fluorescence and associated micro-beam techniques. This beamline is now partially operational and has completed its first year of working with samples below exemption limits. This paper describes the beamline design and its technical specifications as well as the standard equipment of the experimental stations and the first obtained results.

It has been recognized in Ni-base alloys that the grain boundary chemistry and its microestructural heterogeneities are important factors in the material environmental degradation. Therefore, in this study, we investigated the role of the heat treatments and the obtained microstructure in the IGSCC susceptibility of alloy 600 in environments of pressurized water reactors (PWR). The role of microstructure on the intergranular cracking resistance (IGC) of alloy 600 was also investigated using a modified wedge opening loading specimens which were annealed at 930, 800 and 600°C and also exposed to high purity water pressurized with hydrogen at 300°C. It was found the microstructure induce relatively low crack growth rates associated with the development of significant plastic deformation at the crack tip. In addition, some common features were found between the IGSCC performance and the pre-fatigue cracking conditions. For this purpose, the fatigue crack growth properties of this alloy were also evaluated using the ASTM E 606–92.

Many polymers, paints, and organic-based materials exposed to the space environment undergo dramatic changes and irreversible degradation of physical and functional characteristics. While many protective approaches, including protective coatings and mechanical metal foil wrapping or cladding—especially for synthesized bulk materials, are used to reduce the effects of the space environment, the protection of such materials in space remains a major challenge, especially for future long-duration exploration missions or permanent space stations. In addition to the traditional approaches, surface modification processes are used increasingly to protect or to impart new properties to materials used in the space environment. This article presents a brief overview of the present situation in the field of surface modification of space materials. A number of surface modification solutions that differ from the traditional protective coating approaches are discussed that change the surface properties of treated materials, thus protecting them from the hazards of low Earth orbit and geostationary orbit environments or imparting new functional properties. Examples of their testing, characterization, and applications are provided.

Semiconducting KTaO3 single crystals were investigated as a model potential photoanode for hydrogen production using photoelectrochemical cells. To modify the electronic properties of KTaO3 by reducing the band gap and thereby increasing the absorption of light at longer wavelengths, the crystals were doped during growth. A wide range of dopant elements was used that consisted primarily of transition metal atoms. Most of the crystals exhibited n-type behavior with carrier concentrations from 4 × 1018 to 2.6 × 1020 cm–3. The position of the band edges indicated that the crystals were thermodynamically capable of water dissociation. External quantum yield measurements revealed that the samples were photoactive up to a wavelength of ∼350 nm. The indirect band gap and a parameter denoted as E1 that is related to the direct band edge of the semiconductor, were found to be essentially the same for all of the samples. These results indicate that the various dopants and treatments did not produce changes in the KTaO3 electronic structure that were sufficient to significantly modify the behavior of KTaO3 in a PEC cell.

Metal-graphene contact is of critical significance in graphene-based nanoelectronics. There are two possible metal-graphene contact geometries: side-contact and end-contact. In this paper, we apply first-principles calculations to study metal-graphene end-contact for these three commonly used electrode metals (Ni, Pd and Ti) and find that they have distinctive stable end-contact geometries with graphene. Transport properties of these metal-graphene-metal (M-G-M) end-contact structures are investigated by density functional theory non-equilibrium Green’s function (DFT-NEGF) algorithm. The Transmission as a function of chemical potential (E-EF) shows asymmetric curves relative to the Fermi level. Transmission curves of Ni-G-Ni and Ti-G-Ti contact structures indicate that bulk graphene sheet is n-doped by Ni and Ti electrodes, but that of Pd-G-Pd shows p-doping of graphene by Pd electrode. The contact behaviors of these electrodes are consistent with experimental observations.

Numerical simulations were performed to see the effect of geometrical misalignment in pressure driven flows. Geometric misalignment effects on flow characteristics arising in three types of interconnection methods a) end-to-end interconnection, b) channel overlap when chips are stacked on top of each other, and c) the misalignment occurring due to the offset between the external tubing and the reservoir were investigated. For the case of end-to-end interconnection, the effect of misalignment was investigated for 0, 13, 50, 58, and 75% reduction in the available flow area at the location of geometrical misalignment. In the interconnection through channel overlap, various possible misalignment configurations were simulated by maintaining the same amount of misalignment (75% flow area reduction) for all the configurations. The effect of misalignment in a Tube-in-Reservoir interconnection was investigated by positioning the tube at an offset of 164μm from the reservoir center. All the results were evaluated in terms of the equivalent length of a straight pipe. The effect of reynolds number (Re) was also taken into account by performing additional simulations of aforementioned cases at reynolds numbers ranging from 0.075 to 75. The results are interpreted in terms of equivalent length (Le) as a function of Re and misalignment area ratio (A1:A2), where A1 is the original cross-sectional area of the channel and A2 is the available flow area at mismatch location. Equivalent length calculations revealed that the effect of misalignment in tube-in-reservoir interconnection method was the most insignificant when compared to the other two methods of interconnection

In this work, we establish the use of lithography technique by laser direct writing for fabricating bilayer graphene devices. This technique, which is based on direct laser writing on graphene coated with a photoresist is simple to implement, versatile, and capable of achieving good throughput. Double-layer graphene flakes were obtained by micromechanical cleavage of graphite producing large graphene samples up to 40μm in size. The presence of a bilayer of graphene on SiO2/Si substrate was verified by optical microscopy and resonant Raman spectroscopy. We have measured the four-terminal resistance as a function on the back-gate voltage and found initially p-type doping in graphene, but annealing inside cryostat at 127C° in He atmosphere, the samples become n-type. Our measurements show electron mobility reached values around ˜1,900 cm2/V.s at high electron concentration.

We describe the production of photovoltaic modules with high-quality large-grain copper indium gallium selenide (CIGS) thin films obtained with the unique combination of low-cost ink-based precursors and a reactive transfer printing method. The proprietary metal-organic inks contain a variety of soluble Cu-, In- and Ga- multinary selenide materials; they are called metal-organic decomposition (MOD) precursors, as they are designed to decompose into the desired precursors. Reactive transfer is a two-stage process that produces CIGS through the chemical reaction between two separate precursor films, one deposited on the substrate and the other on a printing plate in the first stage. In the second stage, these precursors are rapidly reacted together under pressure in the presence of heat. The use of two independent thin films provides the benefits of independent composition and flexible deposition technique optimization, and eliminates pre-reaction prior to the synthesis of CIGS. In a few minutes, the process produces high quality CIGS films, with large grains on the order of several microns, and preferred crystallographic orientation, as confirmed by compositional and structural analysis by XRF, SIMS, SEM and XRD. Cell efficiencies of 14% and module efficiencies of 12% were achieved using this method. The atmospheric deposition processes include slot die extrusion coating, ultrasonic atomization spraying, pneumatic atomization spraying, inkjet printing, direct writing, and screen printing, and provide low capital equipment cost, low thermal budget, and high throughput.

La(Fe0.88Si0.12)13 shows peculiar magnetic properties such as the first order paramagnetic-ferromagnetic transition and magnetic-field induced metamagnetic transition accompanied by the lattice expansion. The practical application using the magnetic transition temperature controlled by hydrogen absorption is expected in this compound. Here, the electronic structure of La(Fe0.88Si0.12)13 has been investigated by photoemission spectroscopy using synchrotron soft x-rays. The Fe 3s core-level photoemission spectra below and above the Curie temperature TC exhibit a satellite structure at ~ 4.3 eV higher binding energy than the main peak, which is attributed to the exchange splitting due to the local moment of Fe. The exchange splitting of the Fe 3s photoemission spectrum with the asymmetric line shape shows that the magnetization of La(Fe0.88Si0.12)13 is derived by the exchange split Fe 3d bands like the itinerant ferromagnetism in Fe metal, while the magnetic transition of La(Fe0.88Si0.12)13 is the first order. The valence band photoemission spectrum shows temperature dependence across the TC . The temperature dependence of the photoemission spectra is discussed based on the difference between the electronic structure in the ferromagnetic phase and that in the paramagnetic phase.

We present the experimental results for the first known molecular beam epitaxy (MBE) growth of quasi-one-dimensional PbSe wires on technologically relevant silicon.In this work, we describe the growth and characterization of low-dimensional IV-VI semiconductors as they evolve from one-dimensional dot/dot-chains to one-dimensional structures on a self-organized template epitaxially grown on Si(110). In situ and ex situ characterization were performed at various stages throughout growth by reflection high energy electron diffraction, scanning electron microscopy, and non-contact atomic force microscopy. Initial growths resulted in some preferential alignment of the PbSe dot-chains parallel to the self-organized template in the [-110] direction. By reducing the substrate temperature and increasing the supplemental Se flux, the morphology of dot-chains extend into lengthened one-dimensional structures. This is an important milestone in the fabrication of PbSe quantum wires on technologically relevant silicon.

We demonstrate the shape- and size-controlled synthesis of colloidal ∼10 nm bismuth telluride nanoparticles stabilized by organic ligands in solution. Post-synthetic ligand exchange with oleic acid allows for a quick and simple ligand removal by consecutive washing with basic ammonia solution. Mild spark plasma sintering yields a macroscopic nanostructured bulk solid with nanograins unaltered in size and shape. We present the full thermoelectric characterization with an emphasis on the thermal properties of this material. It will be shown that thus prepared nanostructured bulk solids possess significantly altered physical properties typical for materials with high surface-to-volume-ratios. These alterations have the potential to lead to improved thermoelectric performances benefiting from their phonon-glass electron-crystal behavior.

A cost-effective fabrication method to engineer metamaterial structures with micrometersize features and novel mechanical properties, which are suitable for terahertz applications, is reported herein. The effective metamaterial parameter extraction procedure is employed with the Kramers-Kronig relation to analyze the effective parameters of single- and multilayer metamaterial structures.

In Olkiluoto Finland colloidal silica called silica sol (EKA Chemicals) will be used as a non-cementitious grout for the sealing of fractures of the hydraulic apertures of 0.05 mm or less. The use of colloidal material has to be considered in the long-term safety assessment of a spent nuclear fuel repository. The potential relevance of colloid-mediated radionuclide transport is highly dependent on their stability in different geochemical environments. Objective of this work was to study the effect of ionic strength on stability of silica colloids released from silica gel. Silica gel samples were stored in contact with NaCl and CaCl2 electrolyte solutions and in deionized water. Colloid release and stability were followed for two years by taking the samples after one month and then twice in a year. The release and stability of colloids were followed by measuring particle size, colloidal silica concentrations and zeta potential. The particle size distributions were determined applying the dynamic light scattering (DLS) method and zeta potential based on dynamic electrophoretic mobility.

In dilute NaCl (10-7–10-2 M) and CaCl2 (3 10-7– 3 10-3 M) solutions, a mean colloid diameter was less than 100 nm and high negative zeta potential values suggests the existence of stable silica colloids. After two years, the mean particle diameter was increased but it was still less than 500 nm and absolute value of zeta potential was decreased. In 0.1–1 M NaCl and 0.03–3 M CaCl2 solutions, wide particle size distribution and zeta potential values around zero suggested particle aggregation and instable colloids. In deionized water, particle size remained rather stable and zeta potential remained high negative suggests stable silica colloids. The threshold value of ionic strength was 0.03–0.1 M when salinity had an effect on the stability of colloids. In Olkiluoto, the ionic strength of saline groundwater is order of magnitude higher than the range of effect value obtained in this study. Under the prevailing conditions in Olkiluoto, silica colloids are instable, but the possible influence of glacial melt waters has to be considered.