bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Cost-Effective Fabrication Method for Ionic Polymer-Metal Composites
Authors: Siripong M. , Fredholm Susan , Nguyen Que Anh , Shih Brian , Itescu Johannah , Stolk Jonathan 
Published: April 2011

ABSTRACTTo date, many processes have been used for the preparation of ionic polymer-metal composite (IPMC) artificial muscle membranes from conductive metals and perfluorosulfonic polymers such as Nafion. The most widely used of these methods is the platinum plating process, which involves chemical reduction of ionic salt solutions. Although these chemical electroding techniques produce IPMCs with outstanding surface electrodes and excellent performance characteristics, they are relatively costly and time-consuming. In this paper, we describe a novel fabrication process for fast preparation of low-cost Ni-Au-Nafion IPMCs. The process involves the formation of an adherent surface layer on prepared Nafion through DC sputter deposition of a fine-grained gold film, followed by electroplating of a thin and ductile nickel layer in a solution of aqueous nickel salts and boric acid. Preliminary results indicate that the Nafion-117-based IPMCs produced using this technique exhibit good surface conductivity and promising actuation performance, with 20 mg, 11.5 mm × 4.7 mm cantilever bending samples showing high displacements and tip forces up to 4 grams at 4 V. Our current research efforts are focused on achieving repeatable synthesis techniques and evaluating the properties and performance characteristics of the Au-Ni-Nafion IPMCs, especially in comparison to the popular platinum IPMCs.
Effect of Solvent, Hydrogen Bonding, and thickness of Azopolymer Films on Surface Relief Grating
Authors: Jung Woo-Hyuk , Kim Dong-Yu , Kumar Jayant , McCarthy Stephen P. 
Published: April 2011

ABSTRACTEpoxy-based copolymers were synthesized with N,N-diglycidyl aniline (DGA) and aniline (An), called poly(DGA-co-An), where azo coupling reactions were performed using amino benzonitrile (ABN) and nitro aniline (NA). Two azopolymers were dissolved with both tetrahydrofuran (THF)/dioxane complex solvent and THF to compare the diffraction efficiencies according to solvent. The thin films spin-cast with THF/dioxane showed the better diffractive efficiency than with THF due to the high boil point of the residual dioxane. The azopolymers of two azo bonds were spin-coated at 800 and 1300 rpm where the thicker film showed the better diffractive efficiency. The epoxy-based copolymers synthesized with diglycidyl ether of bisphenol A (DGEBA) and aniline (An) or 3-hydroxyl aniline (HAn) were coupled with hydroxyl nitro amino benzene (HNAB). Hydroxyl groups in chromophores helped to form hydrogen bonding with the nitrogen atoms in the azo bonds and prevented photoisomerization, showing no surface relief gratings under a normal laser intensity of 100 mW/cm2. Polyurethane-based azopolymers were synthesized with disperse orange 17 (DO17) and toluene-2,4-diisocyanate (TDI), which were no hydroxide groups in the main chains, and showed the better diffractive efficiency than the epoxy-based azopolymers with nitro substituents.
A Leakage Current Model for “Flash-like”, Non-Volatile Resistive Switch Memory Cell
Authors: Schroeder Herbert 
Published: April 2011

ABSTRACTAn advanced leakage current model combining the electronic carrier injection /ejection at the electrode interfaces (described by thermionic emission) with the film conduction properties of a thin dielectric film (modelled as wide band gap semiconductor) is used to describe the current-voltage (I-V) curve of a flash-like resistive switch memory cell. Such a cell consists of a metal-insulator-metal capacitor structure with some embedded charge storage elements within the dielectric, e.g. a floating electrode (like in the gate of a “Flash”) or some metallic ions or clusters, which can be charged or discharged by an applied voltage or current. The resulting different conductance levels can be used for a resistive switching memory cell. This contribution presents calculated simulation results on I-V curves in dependence on polarity and concentration of the stored charge as well as on other parameters such as dielectric constant, background homogeneous defect densities in the dielectric and electrode properties. These parameters show a large influence on the switching ratio S = R(high) / R(low), an important parameter for the application in a device.
Experimental Benchmarking of Pu Electronic Structure
Authors: Tobin James G , Moore K T , Chung B W , Wall M A , Schwartz A J , Ebbinghaus B B , Butterfield M T , Teslich N E , Bliss R A , Morton S A , Yu S W , Komesu T , Waddill G D , Van Der Laan G , Kutepov A L 
Published: April 2011

AbstractThe standard method to determine the band structure of a condensed phase material is to (1) obtain a single crystal with a well defined surface and (2) map the bands with angle resolved photoelectron spectroscopy (occupied or valence bands) and inverse photoelectron spectroscopy (unoccupied or conduction bands). Unfortunately, in the case of Pu, the single crystals of Pu are either nonexistent, very small and/or having poorly defined surfaces. Furthermore, effects such as electron correlation and a large spin-orbit splitting in the 5f states have further complicated the situation. Thus, we have embarked upon the utilization of unorthodox electron spectroscopies, to circumvent the problems caused by the absence of large single crystals of Pu with well-defined surfaces. Our approach includes the techniques of resonant photoelectron spectroscopy [1], x-ray absorption spectroscopy [1,2,3,4], electron energy loss spectroscopy [2,3,4], Fano Effect measurements [5], and Bremstrahlung Isochromat Spectroscopy [6], including the utilization of micro-focused beams to probe single-crystallite regions of polycrystalline Pu samples. [2,3,6]
Local Structure and Vibrational Properties of α-Pu, α-U, and the α-U Charge Density Wave
Authors: Nelson Erik J. , Allen Patrick , Blobaum Kerri J. , Wall Mark A. , Booth Corwin H. 
Published: April 2011

AbstractThe local atomic environment and vibrational properties of monoclinic α-Pu, orthorhombic α-U, and the α-U charge-density-wave (CDW) modulation are examined by extended x-ray absorption fine structure spectroscopy (EXAFS). Debye-Waller factors from temperature-dependent EXAFS measurements are fit to a correlated Debye model. The observed Pu-Pu bond Debye temperature is θcD(α-Pu) = 162 ± 5 K for the pure α-Pu phase. The temperature dependence of the U-U nearest neighbor and second nearest neighbor Debye-Waller factors exhibits a sharp discontinuity in slope near TCDW = 43 K, the transition temperature at which the charge-density wave (CDW) in α-U occurs. Our measurement of the CDW using EXAFS is the first observation of the structure of the CDW in polycrystalline α-U.
Evidence of Embryo Formation as a Precursor to the Delta to Alpha-Prime Transformation in a Pu-Ga Alloy
Authors: Blobaum Kerri J.M. , Krenn C. R. , Wall M. A. , Massalski T. B. , Schwartz A. J. 
Published: April 2011

AbstractIt was experimentally observed that a single Pu-2.0 at% Ga sample can be thermally cycled many times, with nearly the same amount of transformation and reversion during each cycle, provided that the sample is annealed at 375°C for 8 hours and then conditioned at 25°C for at least 6 hours. The ambient temperature conditioning period is crucial for obtaining the same amount of transformation to alpha-prime in each thermal cycle. Here, we present results from a series of experiments that investigate the effects of conditioning time and temperature on alpha-prime_formation. When the sample is conditioned at 25°C for times between 0 and 6 hours, the amount of alpha-prime formed is a function of conditioning time. For conditioning treatments between 6 and 70 hours, however, the amount of alpha-prime_formed is nearly constant. Conditioning treatments at –50°C, 150°C, and 370°C all resulted in less alpha-prime_formation than the 25°C treatments. We hypothesize that embryos of the thermodynamically stable alpha phase form during the conditioning treatments, and these embryos form alpha-prime upon subsequent cooling. This result is an indirect confirmation of the Russian Pu-Ga equilibrium phase diagram.
Gas generation from water adsorbed onto pure plutonium dioxide powder
Authors: Veirs Kirk 
Published: April 2011

AbstractThe production of H2 from alpha-particle radiolysis of water adsorbed onto plutonium dioxide powders has been studied. Plutonium dioxide powders with specific surface areas of 1.0 and 21 m2/g were used. The specific surface area strongly affects the amount of water adsorbed. At water coverage between 1 and 2 monolayers the H2 yield per unit of energy deposited into the water is found to be between 0.05 and 0.13 molecules of H2 per 100 eV adsorbed dose (5 to 12 nmols/s W). The H2 yield increases to between 0.29 and 0.58 molecules per 100 eV adsorbed dose (28 to 56 nmol/s W) when the number of adsorbed monolayers of water is between 10 and 20. The latter H2 yield is similar to that of liquid water of 0.45 molecules per 100 eV adsorbed dose
Binary HfO2: SiO2 used as High-k Gate Oxide Material in Combinatorial Material Library Method
Authors: Chao Wen-Hsuan , Wang Lih-Ping , Wang Shu-Huei , Huang Tien-Heng , Wu Ren-Jen , Cheng Hung-Chiao 
Published: April 2011

AbstractHafnium silicates (HfO2:SiO2, HSO) have recently attracted much interest in the fields of fundamental science and technology because they have high dielectric constant and low leakage current. The structure and properties of HSO gate oxides were studied using a combinatorial continuous-compositional-spread method. HSO material libraries were synthesized on a 4-inch wafer at room temperature and at 200°C using a custom-built radio-frequency (RF) sputtering system. The electrical properties of HSO material libraries were measured using metal-oxide-semiconductor structure. X-ray diffraction (XRD) was utilized to characterize the structure and compositions of HSO material libraries. The effects of sputtering conditions on the properties of the HSO gate oxides were investigated. The dielectrics constants (εr) of HSO material libraries treated with rapid thermal annealing (600°C/1min/N2) were in the range 5∼23, as determined by C-V measurement, and the dielectric constant was observed to increase with HfO2 content. The I-V relations of the HSO material libraries indicate that the leakage current decreases as the amount of Si in the HSO films increases. The structural characteristics of HSO films with RTA treatment (1000°C/10sec/N2) varied from the amorphous to the crystalline state (tetragonal and monoclinic phase), according to the composition of material libraries. The correlation among the electrical properties, the composition and the crystal structure of the HSO films is discussed.
Fabrication of Nanoparticles and Microspheres with Uniform Magnetic Half-Shells
Authors: McNaughton Brandon H. , Stoica Vladimir A. , Anker Jeffrey N. , Tyner Katherine M. , Clarke Roy , Kopelman Raoul 
Published: April 2011

AbstractWe report a method for fabricating, anisotropically designed, multiphasic nano-particles with uniform magnetic half-shells. Cobalt layers were deposited onto commercially made non-magnetic polystyrene nanospheres and microspheres, using ultrahigh vacuum vapor deposition, which produced particles with a half-shell of uniform size, shape and magnetic content. Iron was also deposited onto commercially made silica nanospheres and microspheres and was characterized using transmission electron microscopy and scanning electron microscopy. The coercivity of the magnetic material layers, on the substrate-supported spheres, was enhanced compared to the bulk values of such films without spheres. The particles, once removed from the substrate, were amenable to being rotated in solution, which could allow for more accurate physical and chemical measurements in a variety of fluidic environments. Applications for imaging local mechanical, magnetic and electrical environments are also delineated.
Small Molecule Diffusion in Polymer Ultra-Thin Films
Authors: Ordaz Ivan , Singh Lovejeet , Ludovice Peter J. , Henderson Cliffod L. 
Published: April 2011

AbstractThe influence of film thickness and polymer molecular weight on the diffusion coefficient of water in poly(methyl methacrylate) thin films supported on gold coated surfaces has been studied using vapor sorption experiments via quartz crystal microbalance (QCM) methods. Diffusion coefficients for films ranging in thickness from approximately 1 μm to 50 nm were determined. It is observed that the diffusion coefficient of water in PMMA on weakly interacting substrates is a strong function of film thickness, and that the diffusion coefficient decreases drastically as film thickness is reduced below a critical thickness value. Furthermore, it is found that polymer molecular weight also appears to play an important role in determining the diffusion behavior of such polymer thin film systems.
Simulation Study of Confinement Effects on the Melting Transition in Hexane and Decane Monolayers Between Two Graphite Slabs
Authors: Pint Cary , Roth Michael 
Published: April 2011

AbstractThe melting transition in hexane and decane monolayers are studied through use of a canonical ensemble molecular dynamics (MD) simulation method, where the monolayer is physisorbed onto a single, infinite graphite slab, with another confining graphite slab some varying vertical distance from the monolayer. Using a simple united-atom model to depict the alkanes, simulations suggest that the monolayer melting transition is largely dependent upon the average density of the physisorbed monolayer in addition to the spacing between the two graphite slabs. In particular, hexane is studied at two distinct coverages: (i) a fully commensurate (FC) monolayer, and (ii) a uniaxially incommensurate (UI) monolayer with an average density 0.9 times that of the FC monolayer. In the case of no confinement, both the FC hexane and decane monolayers exhibit a power law relation between the melting temperature of the monolayer and the graphite slab separation. In contrast, the UI hexane monolayer deviates from this behavior, suggesting that the power law behavior is an effect of the in-plane space, and how the monolayer melting transition depends upon this in-plane space. Finally, the role of the top (confining) layer corrugation in the power-law relationship, and the importance of this study toward future applications are briefly discussed.
Evidence of re-entrant behavior in laponite-PEO systems
Authors: Baghdadi Hossein , Bhatia Surita R. , Jensen Elizabeth E. C. , Easwar Nalini 
Published: April 2011

AbstractRheology and dynamic light scattering capture re-entrant behavior of laponite-polymer systems. Neat laponite under basics conditions and concentrations of 2wt% or greater forms a viscoelastic soft glass due to electrostatic repulsions. We show that that addition of low molecular weight poly(ethylene oxide) (PEO) melts the glass due to a depletion force. The depletion force speeds up dynamics in the system resulting in a low viscosity solution. A re-entrant viscoelastic solid is formed with the addition of high molecular weight PEO due to the polymer chains bridging between laponite particles. As expected the transition from a low to high viscosity solution scales with the polymer mean square end-to-end distance and gap between laponite particles.
Silica-Supported Au and Pt Nanoparticles and CO Adsorption
Authors: Mott Derrick , Luo Jin , Smith Andrew , Chan Wai-Pan , Bozza William , Sarkhel Anjana , Park Sara , Zhong Chuan-Jian 
Published: April 2011

ABSTRACTThe understanding of the surface properties of metal nanoparticles is essential for exploiting their unique catalytic properties. This paper reports findings of the preparation of silica-supported Pt and Au nanoparticles and the FTIR characterization of CO adsorption on the supported nanoparticles. The nanoparticles were prepared by both a traditional impregnation method and molecular-capping based synthesis method. By comparing the spectroscopic characteristics of CO adsorption on these catalysts, similarities and differences in CO stretching bands have been identified. The findings are significant because important insights have been gained into the surface binding properties of Au and Pt nanoparticle catalysts.
Fabrication and Characterization of Molybdenum Oxide Nanofibers by Electrospinning
Authors: Wang Guan , Huang Xianrong , Dudley Michael , Gouma Pelagia-Irene , Yang Xiaoqing 
Published: April 2011

ABSTRACTMolybdenum oxide/ Poly (ethylene oxide) composite nanofibers were prepared by combining the sol-gel process and electrspinning technique. An ethanol solution of Poly(ethylene oxide) (PEO) was mixed with molybdenum isopropoxide to form a precursor solution. Composite nanofibers were obtained by electrspinning this viscous solution. By calcination of the composite fibers, pure molybdenum oxide nanofibers and nano-rods were obtained with diameters of 100-nanometer scale. Morphology of the fibers has been characterized by scanning electric microscopy. Components and structures of the final products have been identified by EDAX and grazing incidence XRD. Calcination process has been studied by DSC and TG analysis. The real time dynamics of the structural evolution from composite fibers to nanocrystalline metal oxide fibers has been investigated by synchrotron-based in-situ x-ray diffraction.
Synthesis of Au Nano-particles under Energetic Irradiation Fields
Authors: Maeda Nobuhiro , Hiroki Taiei , Hori Fuminobu , Okuda Shuichi , Taniguchi Ryoichi , Kojima Takao , Kambara Tadashi , Abe Tomoko , Iwase Akihiro 
Published: April 2011

ABSTRACTDilute aqueous solutions with Au3+ ions and Polyethylene Glycol Monostearate are irradiated with ∼1 MeV γ-ray from 60Co source, 10 MeV pulsed electrons or 1.6 GeV carbon ions. After the irradiation, the color of solutions changes from buff yellow to reddish color. The UV-vis absorption spectra show that after the irradiation, light absorption around 530 nm appears, which corresponds to the excitation of the surface plasmon due to Au nano-particles. The result confirms that the irradiation reduces Au3+ ions in the aqueous solutions and synthesizes Au nano-particles. Size and shape of the nano-particles are examined by using 200kV transmission electron microscope. Effects of irradiation parameters (total dose and dose rate) on Au nano-particle synthesis are discussed.
Mechanochemical Synthesis, Structural Characterization and Visible Light Photocatalysis of TiO2/ZnFe2O4 Nnanocomposites
Authors: Srinivasan Sesha S. , Kislov Nikolai , Wade Jeremy , Smith Matthew , Stefanakos Elias , Goswami Yogi 
Published: April 2011

ABSTRACTNanocomposite heterogeneous semiconductors with suitable energy levels (gaps) are exhibiting excellent photocatalytic properties under visible light irradiation. TiO2/ZnFe2O4 has been selected among different alloys because of (i) its low band gap ∼1.9 eV (ii) the nontoxicity of ZnFe2O4 (iii) visible light absorption characteristics of ZnFe2O4 due to its narrow band gap and (iv) not being susceptible to photoanodic corrosion. A mechanochemical synthesis approach using high energy milling is employed to prepare TiO2/ZnFe2O4 under different experimental parameters and conditions. The effects of ball milling and calcination on the photocatalytic behavior of TiO2 and TiO2/ZnFe2O4 have been determined. The as-milled nanocomposite materials are characterized with PXD, SEM and EDS procedures. The photocatalytic activity of TiO2/ZnFe2O4 nanocomposites for the photodegradation of phenol under visible light irradiation has been studied systematically by UV-Vis spectrometer. It is interesting to note a red shift of 0.25 eV in the absorption edge of the ball-milled TiO2 sample when compared to the non ball milled TiO2 photocatalyst.
Practical Nanomaterials and Nanostructures in Electronics
Authors: Rae Alan 
Published: April 2011

ABSTRACTA quiet revolution is occurring in electronics where nanometals have the ability to revolutionize adhesives and solders, nano oxides are revolutionizing fuel cell efficiency, and nanowires as well as nanotubes have the potential both to enhance short term evolutionary and long term revolutionary improvement.This paper outlines some roadmap predictions and picks three areas with concrete examples- nano metals for ink jet formation of circuits, nano oxides in fuel cells, and lithographically developed nanowires for sensor application and details technical and commercial progress.
Fabrication of Highly-ordered and Densely-spaced Silicon Nano-needle Arrays for Bio-sensing Applications
Authors: Yin Aijun , Xu Jimmy 
Published: April 2011

ABSTRACTIn this work, we report a success in fabricating highly-ordered and densely-packed array of silicon nano-needles that are vertically aligned, straight and long, meeting many of the requirements for biomolecular sensing and integration with silicon electronics. Yet, we show that they can be fabricated with a relatively simple and non-lithographic method.In this approach the array of nano-needles of high uniformity in length and diameter are made out of silicon by reactive ion etching (RIE) through either an anodic aluminum oxide (AAO) membrane or an array of metallic nano-dot caps that are evaporated on a silicon wafer using an AAO membrane as mask. The AAO membrane itself is formed non-lithographically via anodization of pure aluminum foil and contains an array of highly-ordered and highly-uniform nano-pores. By using the AAO membrane either directly as an etching mask or as an evaporation mask to deposit metallic nanodots which in turn serve as an etching mask, deep and high aspect-ratio etching is possible to allow the formation of the nanoneedles in a Si substrate.
Characteristic Comparison Of Epitaxial PZT And PMN-PT Films Grown On (100)cSrRuO3//(100)SrTiO3 Substrates By Metalorganic Chemical Vapor Deposition
Authors: Yokoyama Shintaro , Okamoto Satoshi , Saito Keisuke , Iijima Takashi , Okino Hirotake , Yamamoto Takashi , Nishida Ken , Katoda Takashi , Sakai Joe , Funakubo Hiroshi 
Published: April 2011

AbstractWe grew the epitaxial Pb(Zr1-xTix)O3 [PZT] and (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 [PMN-PT] films, above 2 μm in thickness, on (100)cSrRuO3//(100)SrTiO3 substrates by metalorganic chemical vapor deposition (MOCVD). PbTiO3 content (x) dependencies of the crystal structure, dielectric and piezoelectric properties were systematically investigated for these films. The constituent phase changed from a rhombohedral (pseudocubic) single phase, a mixture phase of rhombohedral (pseudocubic) and tetragonal phases, and a tetragonal single phase with increasing x for both of PZT and PMN-PT films. The mixture phase region was observed when x=0.40−0.60 for PZT films and x=0.40−0.55 for PMN-PT films, which became wider than that reported ones for PZT sintered bodies and PMN-PT single crystals. In addition, x value moves to the higher one than that reported for the single crystal and/or the sintered body in case of PMN-PT films, while was almost the same in case of PZT films. The dependence of relative dielectric constant εr was maximum at the mixed phase region for both films, which were similar to the case of their bulk materials. The higher value of εr was ascertained for the PMN-PT films compared with PZT films, however, the magnitude was lower than the reported one for bulk materials. The longitudinal electric-field-induced strain Δx33 and transverse piezoelectric coefficient e31,f for PZT films were also maximum at the mixed phase region, on the other hand, that for PMN-PT films were maximum at larger x edge of rhombohedral (pseudocubic) region. Almost the same order of Δx33 was observed under applied electric fields up to 100 kV/cm, while larger e31,f was observed in PMN-PT films compared with the case of PZT films. e31,f coefficients of ∼−8.9 C/m2 and ∼−11.0 C/m2 were calculated for the PZT film with x=0.46 and for the PMN-PT film with x=0.39, respectively.