The pyrolysis of ion exchange resin beads that are used for the purification of water in reactor primary- and secondary-cooling circuits can result in stable and leach resistant carbonaceous products. However, free flowing beads are less desirable waste forms for disposal in sub-surface or surface repositories than monolithic masses of low porosity. We have investigated the pyrolysis of polymeric resin – cation exchange resin composites to give mechanically robust and chemically durable monolithic carbonaceous waste forms that are suitable for repository disposition. Also investigated was the dependence of product properties on various processing parameters (temperature ramp and final temperature). As a first approach, epoxy resins were used for the preparation of monoliths since such resins cure at room temperature and result in a relatively high carbon yield. Carbonaceous monolithic products were prepared at 400, 500, 600, 700 and 800 °C using a temperature ramp of 2°C/min. The products were maintained at the chosen temperatures for a period of one hour. Mass losses, volume reduction, hardness and compressive strength were measured and mathematical functions are proposed to describe the measured values of these properties. The carbon monoliths were observed to be mechanically robust.

We have investigated the criterion of interfacial crack initiation in nanometer-scale components (nano-components) by means of a loading facility built in a transmission electron microscope (TEM). Three types of experiments are conducted in this project. (1) In order to clarify the applicability of conventional continuum mechanics to the nano-components, we prepare cantilever specimens with different size, which introduce different stress fields, containing an interface between a 20 nm-thick copper (Cu) thin film and a silicon (Si) substrate. These demonstrate the validity of the “stress” criterion even for the nano-scale fracture. (2) In order to examine the effect of microscopic structure on the mechanical property, we fabricate a bending specimen in the nano-scale with thin Cu bi-crystal (the thickness of about 100 nm) formed on Si substrate, of which understructure can be observed in situ by means of a TEM during the mechanical experiment. The initial plastic deformation takes place near the interface edge in a grain with a high critical resolved shear stress and expands preferentially in the grain. Then, the plasticity appears near the between Cu grain boundary and Cu/Si interface, and this development brings about the interfacial cracking from the junction. These indicate the governing influence of understructure on the mechanical property in the nano-components. (3) In order to investigate the fatigue behavior of metal in a nano-component, a cyclic bending experiment is carried out using nano-cantilever specimens with a 20 nm-thick Cu constrained by highly rigid materials (Si and SiN). The high strain region is in the size of 20-40 nm near the interface edge. The specimen breaks along the Cu/Si interface before the maximum load under the fatigue loading. The load-displacement curve shows nonlinear behavior and a distinct hysteresis loop, indicating plasticity in the Cu film. Reverse yielding appearing after the 2nd cycle suggests the development of a cyclic substructure in the Cu film. These indicate that the crack is caused by characteristic understructure owing to fatigue cycles.

Preparation of the CaTiO3:Pr (CTO:Pr) phosphor thin film on PET substrate was investigated by using the excimer laser-assisted metal organic decomposition(ELAMOD) and photo reaction of nano-particles (PRNP) process. The effects of the substrate material, starting materials, and UV sources on photoluminescence (PL) were investigated. By using the BaTiO3(BTO) nano-particles buffer layer and the CTO: Pr nano-particles as a starting material, CTO: Pr thin film on the PET substrate was successfully obtained by using the KrF laser and excimer lamp irradiation at 25°C. It was found that excimer lamp irradiation is effective for improving the PL of the films.

This study examined surface modification of solder resist and dry film resist using 60 Hz nonequilibrium atmospheric pressure plasma with O2/N2 mixing gas. Results show that the plasma discharge condition at O2/N2 mixing ratio of 0.1% was the best for surface modification for both materials, and the surfaces were modified sufficiently at 0.45 m/min package substrate transportation speed. From the plasma diagnostics by Vacuum Ultraviolet Absorption Spectroscopy (VUVAS) and Optical Emission Spectroscopy (OES), it was found that the behaviors of the oxygen radical density and NO-γ emission intensity correlate strongly with surface modification. The extremely high oxygen radical density around 4.7 × 1013 cm-3 was obtained at O2/N2 mixing ratio of 0.1%. The electron density was 2.5 × 1015 cm-3 that is two digits more than that of the conventional atmospheric pressure plasma such as Dielectric Barrier Discharge (DBD). The solder resist surface with the plasma treatment was analyzed by X-ray Photoelectron Spectroscopy (XPS), and it was clarified that material surface was modified by hydrophilic group generation owing polymer chain oxidation with oxygen radical.

Identical samples of uranium coupons were prepared and each exposed to hydrogen for different times (where this time is significantly less than a classically understood ‘induction time’). Samples were prepared from rolled depleted uranium stock: as-received oxide was removed on all surfaces and two faces (~12x12 mm) were polished to a sub-micron standard. Samples were individually taken through a Vacuum Thermal Pre-Treatment cycle from room temperature to 200°C to the reaction temperature (80°C) over 40 hours and subsequently exposed to 10 mbar O2 for 24 hours. After O2 was removed, the samples were exposed to hydrogen for pre-determined times of up to 48 minutes. Examination of the samples by Scanning Electron Microscopy (SEM) has, as expected, identified small features protruding from the surface believed to have been caused by sub-surface precipitation of UH3. In general these features are circular and isolated from each other, have a diameter of less than 3μm and appear as either ‘flat-topped’ or ‘domed’ morphology. In addition, longer time exposure samples show a predominance of ‘area attack’ where coalesced sub-surface precipitation appears to be confined to particular metal grains. X-Ray Diffraction (XRD) data show an increase in the quantity of UH3 with time.

An inductor in standard CMOS process having an inductance of 52 nH and a quality factor of 1.5 at frequency equal to 80 Mhz was fabricated. The polymer passivation layer of the standard CMOS inductor was etched out. The silicon substrate under the inductor, having a thickness of 280 μm was also etched out by deep reactive ion etching (DRIE). Ferrite material ZnFe2O4 and amorphous material Fe4.7Co70.3Si15B10 was then sputtered on top of the inductor sequentially. The same sputtering procedure was also performed into the bottom of the inductor. The result is an inductor that is sandwiched by multiple ferromagnetic layers. The inductance of the new ferromagnetic inductor has increased by 15% from 52 nH to 60 nH. The quality factor has also increased by 20% from 1.5 to 1.8.

Materials with a remarkable combination of high electrical conductivity as well as optical transparency are playing a key role for opto-electronic devices. In addition to these specific electro-optical properties, transparent conductive materials should, for many applications, be lightweight, flexible, low-cost, non toxic and compatible with mass production techniques. In these regards, the use of Ag nanowire (Ag NW) networks appears to be a promising approach. In this study, Ag NW electrodes were fabricated by a novel spray injection method. The number of pulses was varied resulting in different network morphologies. Coatings were systematically characterised structurally, electrically and optically via SEM, four-point probe measurements and spectrophotometry, respectively. Semi uniform layers of nanowires with large haze coefficients have been obtained over large areas. Thermal annealing was shown to increase the nanowire film conductance resulting in 16 Ω/sq surface resistance and up to 73% maximal total transmittance. Films showed average optical transparencies superior to that of ITO over the 250-2500 nm range. Finally, encapsulation of Ag NWs within a matrix of ZnO nanoparticles greatly enhanced the thermal stability of these networks.

The β titanium alloys are highly attractive metallic materials for biomedical applications due to their high specific strength, high corrosion resistance and excellent biocompatibility, including low elastic modulus. The aim of this work is the evaluation of hardening mechanism through phase separation in β Ti-35Nb-7Zr-5Ta (TNZT) and Ti-35Nb-7Ta (TNT) alloys. Ingots (50 g) of TNZT and TNT alloys were arc-furnace melted in Ar(g)atmosphere. XRD using synchrotron radiation together with TEM and HRTEM analysis showed the coexistence of two separated phases (β and β’) with similar crystalline structures and slightly different lattice parameters in TNZT and TNT alloys. It was detected a heterogeneous microstructure alternating nanosized dark and bright regions (∼10 nm) with different compositions (Nb-rich β and Ta-Zr-rich β’).In aged condition (400ºC/4h), TNZT and TNT alloys undergoes coherent spinodal decomposition of β phase into two solid solution phases with coherent interface, different compositions and elastic strain associated with nanometric domains of Nb-rich β and Ta-(Zr)-rich β’ phases.

The paper presents the analysis of Raman scattering spectra of non-conjugated and bio-conjugated CdSe/ZnS core–shell quantum dots in the range of Raman shifts of 80 - 2000 cm-1. Commercial CdSe/ZnS QDs covered by polymer and characterized by color emission with the maxima at 605 and 655 nm (1.89 and 2.04 eV) were used. Raman scattering spectra were measured at 300K and the excitation by the line 785.0 nm of a solid state LED. The analysis of Raman spectra has shown that the QD bio-conjugation to the immunoglobulin G (IgG) antibodies of the Pseudorabies virus is accompanied by the changes of the intensity of Raman lines related to the CdSe/ZnS core/shell QDs, PEG polymer covered QDs, the Si substrate and/or some organic groups of antibody molecules. The comparison of Raman spectra of CdSe/ZnS QDs with different sizes in non-conjugated and bio-conjugated states gives the opportunity to detect the bio-conjugation without mistake.

Graphite electrode surface degradation mechanisms and formation of solid electrolyte layers (SEI) at the interface with the electrolyte were studied as a function of the applied voltage and voltage scan rates using in situ optical microscopy. Voltammetry tests were initiated from a peak voltage of 3.00 V during which the voltage was decreased to a constant base potential (0.02 V) using different scan rates of 0.05-5.00 mV/s. Cross-sectional FIB microscopy indicated that graphite surface and subsurface damage -- in the form of loss of material from graphite -- was reduced when dense and continuous deposits of SEI formed at low scan rates (e.g. 0.05 mV/s).Whereas, non-uniform and discontinuous SEI formed at high scan rates (∼ 5.00 mV/s) was unable to alleviate graphite surface damage.

A strong resonance in the inverse photoelectron spectroscopy (IPES) of cerium oxide was reported recently. Here, it is shown that dominance of the indirect channel of the resonant inverse photoelectron spectroscopy (RIPES) is so complete that the photon energy dependence can be explained in terms of emission associated with a single photon energy.

This paper focuses on developing a robust process to independently control the geometrical parameters of Si nano-pillar (NP) arrays. These parameters include height and diameter of NPs, spacing between them, and the shape of the NPs. We have shown that the diameter, height, and spacing of NPs can be independently engineered by controlling the diameter of nano-beads through synthesis procedure, duration of isotropic SiO2 etching and duration of anisotropic Si etching, respectively.

Pyrite phase of FeS2 has attracted substantial attention in the field of thin film solar technology because of its high optical absorption coefficient (~5 x 105 cm-1 at hν > 1.3eV) and the band gap of 0.95 eV. In this research, we have grown highly pure iron pyrite films using a low temperature atmospheric pressure chemical vapor deposition technique. The synthesis temperature is in the range of 375-400°C and Di-tert-butyl disulfide (TBDS) is used as the sulfur precursor. TBDS is a safe and low cost sulfur source unlike H2S, which is highly toxic and requires extreme care in handling. The films obtained were uniform and free from common impurity phases such as troilite and marcasite. The FeS2 films grown earlier with CVD synthesis and sulfurized using H2S had pinholes and contained secondary phases like marcasite and troilite. The FeS2 pyrite phase was confirmed using various characterization techniques that included SEM, EDS, XRD and XPS.

Geckos can cling to almost any surface using dense arrays of microscopic hierarchical hairs called setae. The flat, regular, terminal branches of the setae adhere by the van der Waals dispersion force, and the mechanics of the gecko attachment scheme are a current topic among biologists and researchers in smart materials for adhesion. We studied the friction behavior of natural gecko arrays. Our experiments demonstrate the presence of velocity strengthening dynamic friction over the range of velocities from 5×10–4 to 158 mm/s and a range of specimen elastic moduli from 1.1 to 3.6 GPa. From these dynamic experiments, we calculate low-v activation volumes between 1500 and 3000 nm3. Since these volumes are 3 orders of magnitude larger then are typical for bulk materials, we conclude that there is weak coupling between individual sliding contacts in the gecko system.

ABSTRACT

Shape-controlled Ag and Pd nanocrystals were synthesized using seed-mediated techniques using β-cyclodextrin (β-CD) as structuring agent. First, seeds were obtained by reacting Na2PdCl4 or AgNO3 with a strong reducing agent, NaBH4 in the presence of sodium citrate dihydrate acting as stabilizing agent. These seeds were then injected into a growth solution containing the same metallic precursor, ascorbic acid (as a weak reducing agent) and β-CD as structuring agent. TEM results emphasize a strong influence of the relative concentration of β-CD on the final morphology. In the case of silver, well-facetted nanocrystals were obtained with a progressive shift from kinetically to thermodynamically-controlled nanoobjects when increasing the β-CD/Ag molar ratio. On palladium, β-CD leads to the formation of dendrites (urchin-like) or multipods through controlled aggregation of primary particles. The use of β-CD does not interfere negatively with the catalytic properties of the Pd nanocrystals in the hydrogenation of cinnamaldehyde.

Changes in the material properties of copper (II) phthalocyanine (CuPc) thin-films were studied upon exposure to increasing dose of ionizing radiation using photoluminescence spectrum. We observe generation of new energy states below the band gap upon exposure to ionizing radiation. Organic electronic devices – CuPc based resistor and an organic field effect transistor (OFET) – are proposed in this work as total dose sensors for ionizing radiation. We observe an increase in the conductivity of CuPc thin-films with increasing dose of ionizing radiation. To overcome the possibility of changes/degradation in the electrical properties of CuPc thin-films upon interaction with various gases and moisture in the environment, a passivation layer of silicon nitride, deposited by hot-wire CVD process is proposed. Effect of ionizing radiation on the electrical properties of thin-films of CuPc has been studied. We observe a 170% increase in the resistance of the thin-film for a total of 50 Gy radiation dose using Cobalt-60 (60Co) radiation source. Moreover, significant changes in the electrical characteristics of an OFET, with CuPc as an organic semiconductor, have been observed with increasing doses of ionizing radiation. Experiments with an OFET (W/L = 19350 μm / 100 μm and tox = 150 nm) as a sensor resulted in a ∼100X change in the OFF current for a total of 50 Gy dose of ionizing radiation exhibiting a sensitivity of ∼1 nA/Gy. Moreover, implementing a reader circuit, shift in the threshold voltage of the OFET at 1e-7 A drain current displayed a sensitivity of 80 mV/Gy for a total of 50 Gy dose of ionizing radiation. CuPc based organic electronic devices have advantages as sensors because of their low-cost fabrication, large area coverage on flexible substrates, etc.

Zinc oxide (ZnO) nanoparticles were produced using chemical precipitation synthesis with a molar ratio of 1:1, 1:2 and 1:3. The structure, chemical composition and morphology were investigated by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). XRD and EDS demonstrated that the all particles formed at different atomic proportion were of wurtzite crystal structure with the same chemical composition. SEM and TEM showed the formation of hexagonal particles with a molar ratio of 1:1 while the samples synthesized with a molar ratio 1:2 and 1:3 showed a circular shape. HRTEM and Fast Fourier Transform (FFT) demonstrated that the all particles were formed with a preferable [0001] growth direction.

A setup is described where an individual electrospun polyamide fiber is attached to an atomic force microscope (AFM) tip and structural information collected with synchrotron micro Fourier transform infrared spectroscopy (μFT-IR). The combination of AFM and synchrotron μFT-IR therefore highlights the potential for recording structure-mechanical property relationships simultaneously in materials with sub-micron dimensions.

The LaFeO3 and CaFeOX layers are grown using highly dense target prepared by Pechini method, with which accurate growth rate is achieved. Since the LaFeO3demonstrates the obvious RHEED oscillation until the end of growth, constant growth rate, and the step-terraces structure, the LFO is employed as a buffer and/or reference layer to determine the required pulses to deposit the thickness we desire in the superlattice. Superlattices show the clear satellite peaks and Laue oscillation in the XRD spectra as well as the oscillations caused by the film thickness with a flat surface and superstructure with a flat interface in the x-ray reflection spectrum. The streaky RHEED patterns and step-terraces surface are consistent with the results of spectra using x-ray.