bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of Impact Strength for Transparent Inorganic Glass by Electron Beam Irradiation
Authors: Iwata Keisuke , Tonegawa Akira , Nishi Yoshitake 
Published: April 2011

ABSTRACTLow-energy electron beam (EB) irradiation, generally applied to enhance hardening and wear resistance of polymer, was a successful surface treatment. Effect of EB irradiation was the homogeneous activation of surface atoms and the breaking of the chemical bonds in the network structure of a surface layer of inorganic glasses. When EB irradiation generated dangling bonds at the weaker-bonded metal-oxygen atomic pairs in the glass network structure, partial relaxation occurred at points of residual strain in the network structure. It was clear that the increased rigidity was mainly due to an increase in the bonding energy of the stronger-bonded metal-oxygen atomic pairs in the atomic network structure. The possible beneficial effects of EB irradiation on the impact value of transparent inorganic glass was investigated. To clarify the results, ESR observations were used to confirm the existence of dangling bonds. The EB irradiation increased the impact value of the transparent inorganic glasses. Based on the ESR signals of transparent glasses before and after EB irradiation, the high density of dangling bonds was obtained.
Enhanced Light Emission by Exciton-Surface Plasmon Coupling
Authors: Okamoto Koichi , Scherer Axel , kawakami Yoichi 
Published: April 2011

ABSTRACTSurface plasmon coupling technique was performed to enhanced green light emissions from InGaN/GaN quantum well. We found that photoluminescence intensities were increased by fabricated nano-grating structures on the gold layers and enhancement ratios depend on the grating periods. We also simulated the localized SP modes by 3D-finite difference time domain (FDTD) calculation. The experimental results were well correlated to the calculated results, and we found that the both exciton-SP coupling and light extraction process can be controlled by the nano-structures of the interfaces. This suggests that even more efficient emission should be obtainable by optimizing the nanostructure geometries.
Interaction of Spherical Nanoparticles with a Highly Focused Beam of Light
Authors: Sendur Ibrahim Kursat , Challener William , Mryasov Oleg 
Published: April 2011

ABSTRACTInteraction of a highly focused beam of light with spherical nanoparticles is investigated for various incident field polarizations. First, an analytical solution is obtained to calculate the interaction of a highly focused beam of light with a spherical particle. To accurately express the incident electric field near the focus of an aplanatic lens, the technique established by Richards and Wolf is used. Using this analytical solution, electric field distributions of various spherical nanoparticles made of silver are investigated for highly focused linearly and radially polarized beams. The effect of the half angle of the focused beam is investigated. In addition a three-dimensional finite element method based solution is obtained and compared with the analytical solution for problems involving a highly focused beam of light interacting with a spherical particle.
Arrays of Well-Defined Size-Tunable Metallic Nano-Cones for Plasmonic Applications
Authors: Fleischer Monika , Stade Florian , Heeren Andreas , Haeffner Michael , Kern Dieter P. , Braun Kai , Stanciu Catrinel , Meixner Alfred J. 
Published: April 2011

ABSTRACTCones composed of noble metals with dimensions of the order of 100 nm, especially gold cones, are extremely well suited for optical near-field investigations using visible light. Their plasmon resonance frequency lies within the range of visible light frequencies, and upon illumination, strong electric field enhancement can be observed in the direct vicinity of the cone tip. For this purpose, a method to fabricate well-controlled nanocones with sharp tips is required. We present a top-down process in which arrays of cones are dry-etched from a metal stack on silicon. During the ion milling step, patterned hydrogen silsesquioxane resist is used as an etch mask. The resulting cones have tunable base diameters around 150 nm and tip radii down to less than 10 nm. Their optical characteristics are investigated by means of apertureless optical near-field microscopy, in which field enhancement at the cone tip is observed.
Near infrared intersubband absorption in cubic GaN/AlN superlattices
Authors: DeCuir Eric A. , Fred Emil , Manasreh Omar , Schormann Jorg , As Donat J. , Lischka Klaus 
Published: April 2011

ABSTRACTRoom temperature near-infrared intersubband transitions were observed in MBE grown non-polar cubic GaN/AlN superlattice structures. The peak wavelengths of these transitions were observed in the spectral region of 1.5–2.0 μm and were theoretically supported using a transfer matrix approach. All samples were unintentionally doped and grown on 3C-SiC substrates with a 100 nm GaN buffer. Each structure consisted of a 20 periods of GaN/AlN superlattice capped with 100nm of GaN. The thickness of the AlN barrier was fixed at 1.35, while the thickness of the GaN well was varied between 1.6 and 2.1nm. Electrochemical Capacitance Voltage (ECV) measurements allowed direct measurement of the intrinsic carrier concentration in a thick unintentionally doped cubic GaN layer, which confirmed sufficient population of the ground state energy level.
Surface Passivated Air and Moisture Stable Mixed Zirconium Aluminum Metal-Hydride Nanoparticles
Authors: Epshteyn Albert , Miller Joel B. , Pettigrew Katherine A. , Stroud Rhonda M. , Purdy Andrew P. 
Published: April 2011

ABSTRACTSynthesis of surface passivated Zr-Al mixed metal-hydride nanoparticles was accomplished via a multi-step process. The initial reaction to produce the zirconium aluminum hydride was via decomposition of zirconium tetrahydroaluminate (Zr(AlH4)4) while exposed to ultrasound produced by a benchtop ultrasonic bath. The particles were surface passivated using carbohydrates and were shown to be stable in air and partially stable in water. TEM imaging suggests the existence of smaller particles made of a Zr-Al alloy that range in size from 1.8 nm to 7.9 nm in diameter and are interspersed with larger particles that range from tens to hundreds of nanometers in diameter. It was also shown that the carbohydrate-derived coating of the nanoparticles is present as an aluminum alkoxide gel surrounding the core particles.
Carbon-Halide Nanocomposites for Asymmetric Hybrid Supercapacitors
Authors: Barpanda Prabeer , Fanchini Giovanni , Amatucci Glenn G 
Published: April 2011

ABSTRACTNanostructured materials and nanocomposites have inspired many structural and functional applications in recent time. In the last decade, energy-storage devices have employed electrode materials in form of nanomaterials/nanocomposites to yield promising electrochemical performance. The current paper throws light on the application of nanostructured pristine activated carbons as well as chemically modified carbon-halide nanocomposites in practical electrochemical supercapacitors. Pristine activated carbons have been mechanochemically modified via high-energy milling and iodine doping to produce carbon-halide nanocomposites. A significant change in existing physical and electrochemical properties has been marked by introduction of iodine into carbon and the subsequent formation of nanocomposites. The effect of halides and nanoscale morphology is discussed using X-ray, Raman spectroscopy, DSC, BET analysis and electrochemical testing.
Spectroscopic Investigations of Dendrimer-Au Hybrid Nanoclusters
Authors: Tanaka Akinori , Murase Yoshiaki , Kitagawa Takanobu , Imamura Masaki , Yasuda Hidehiro 
Published: April 2011

ABSTRACTWe have synthesized the dendrimer-Au hybrid nanoclusters by solution routes, and have carried out the various spectroscopic studies in order to investigate their electronic structures. From the line-shape analyses for Au 4f core-level photoemission spectra measured with hard X-ray synchrotron-radiation of Au nanoclusters with mean diameter of 2-3 nm stabilized outside the dendrimer, it is found that Au 4f core-level photoemission spectrum consists of two components. We attribute these components to interior Au atoms and surface Au atoms bonded to dendrimers. In the valence-band photoemission spectrum of these Au nanoclusters, we have observed the bandwidth narrowing of Au 5d-derived band compared to that of bulk Au crystallite. Moreover, we have observed the characteristic spectral feature in the vicinity of Fermi level due to the dynamic final-state effect in photoemission. We have also carried out the optical spectroscopic measurements of these Au nanoclusters. From these results, we discuss the electronic structures and interfacial properties of the dendrimer-Au hybrid nanoclusters.
Effect of Ligand Exchange on the Stability and Optical Properties of CdSe Quantum Dots
Authors: Siy Jacqueline T. , Leone Lindsay , Bartl Michael H. 
Published: April 2011

ABSTRACTA new post-synthesis heat/ligand-exchange treatment on CdSe nanocrystal quantum dots that allows fine-tuning the quantum dots size without losing important properties (e.g. photoluminescence) is presented. The careful control of parameters such as the reaction temperature, the quantum dot to alkyl-amine ligand mole ratio and the solvent volume is shown to provide tunable size reduction of the nanocrystals. This size reduction phenomenon provides new insights into the surface chemistry and stability of nanocrystals and can serve as a platform for designing, controlling and processing nanomaterials with tailored properties.
Synthesis and Characterization of Plasma Synthesized Nanostructured Magnesia-Yttria Based Nanocomposites
Authors: Al-Sharab Jafar F. , Sadangi Rajendra , Shukla Vijay , Kear Bernard 
Published: April 2011

ABSTRACTPolycrystalline Y2O3 is the material of choice for IR windows since it has excellent optical properties in the visible, and near infra-red band. However, current processing methods yield polycrystalline Y2O3 with large grain size (> 100 μm), which limits the hardness and erosion resistance attainable. One way to improve strength is to develop an ultra-fine grained material with acceptable optical transmission properties. To realize a fine-grained ceramic, one approach is to develop a composite structure, in which one phase inhibits the growth of the other phase during processing. In this study, Y2O3-MgO nanocomposite with various MgO content (20, 50 and 80 mol%) were synthesized using plasma spray method. Extensive characterization techniques including x-ray diffraction, scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy Dispersive spectrometry (EDS) were employed to study the synthesized powder as well as the consolidated sample. Transmission Electron Microscopy, as well as EDS chemical mapping, revealed that the consolidated sample have bi-continuous MgO-Y2O3 nanostructure with an average grain size of 200 nm.
Cu Rich Nanostructured Alloys with Enhanced Mechanical Properties
Authors: Georgarakis K. G. , Ota K. , LeMoulec A. , Charlot F. , Yavari A. R. , Vaughan G. 
Published: April 2011

ABSTRACTNew copper rich alloys with elemental additions of transition metals and group IIIA and IVA elements have been prepared by casting and rapid solidification. The prepared alloys show very interesting microstructures; a thick surface layer with nanocrystalline eutectic like structure, while in the bulk the microstructure is coarser lamellar or dendritic. Their microhardness was found to be exceptionally high for Cu rich alloys, reaching values of 450-550HV. Furthermore, the microhardness of the surface layer is higher than that in the bulk, indicating that these alloys can be considered for a variety of applications including tribological and structural.
CVD deposition of highly Al-rich mullite coatings
Authors: Kulkarni Tushar , Wang H Z , Basu S N , Sarin V K 
Published: April 2011

ABSTRACTAlthough chemical vapor deposited mullite (3Al2O3•2SiO2) environmental barrier coatings have shown promise in protecting Si-based substrates for gas-turbine applications, there is concern that the silica content within the mullite coating itself might be susceptible to hot-corrosion and recession during long term exposure to corrosive atmospheres. There is thus a strong motivation to substantially reduce or even virtually eliminate the silica from the surface of the mullite coatings that are in direct contact with atmospheres containing corrosive oxides and steam. Functionally graded mullite (3Al2O3•2SiO2) coatings have been grown for Si-based substrates and the composition has been tailored in these coatings, with the Al/Si ratio being stoichiometric (∼ 3) at the coating/substrate interface for coefficient of thermal expansion (CTE) match, and increasing monotonically towards the outer coating surface. These functionally graded coatings have some of the highest Al-rich mullite reported to date at the coating surface. At these extremely high Al/Si ratios, mullite structure breaks down and the formation of a nano-sized high-alumina rich phase occurs. High-resolution transmission electron microscopy has been used to characterize the structure and composition of high alumina mullite and will be discussed.
Fabrication of Multiwall Carbon Nanotube-nanocrystalline Copper Nanocomposite Film by Electrochemical Deposition
Authors: Yoo JungJoon , Song JaeYong , Yu Jin 
Published: April 2011

ABSTRACTA new method of fabricating nanocomposite films made up of multiwall carbon nanotube and nanocrystalline copper was developed by using an electrochemical deposition. The electroplated CNT/Cu nanocomposites have the microstructure that CNTs are well dispersed in both the planar and depth directions without any voids in the matrix. The conditions were successfully achieved by using some amphiphilic polymers, organic additives and a pulse electrodeposition method. The microstructure and CNT composition of nanocomposite films were strongly affected by the concentration of CNT in the electrolyte. The mechanical and electrical properties of CNT/Cu nanocomposite films were investigated with the variation of CNT content in the nanocomposite films.
New Core/Shell Ta2O5-PMMA Nanocomposites for Applications as Polymer Waveguides
Authors: Szabó Dorothée Vinga , Ochs Rolf , Schlabach Sabine , Ritzhaupt-Kleissl Eberhard , Hanemann Thomas 
Published: April 2011

ABSTRACTTo realize ceramic/polymer nanocomposites for polymer waveguides, PMMA-coated Ta2O5 nanoparticles are synthesized as core/shell particles. Therefor a gas-phase process is used: the Karlsruhe Microwave Plasma Process. The organic coating is supposed to reduce the agglomeration of the ceramic cores and should facilitate the incorporation into the polymer resin. TEM investigations of the nanoparticles exhibit crystalline and amorphous Ta2O5 with sizes around 3 to 6 nm, confirmed by electron diffraction. Although the polymer coating is not visible in TEM imaging, electron energy loss spectroscopy (EELS) exhibits a significant C-edge, proofing the organic coating. The Ta2O5/PMMA nanoparticles are incorporated with different weight fractions to a maximum of 1 wt% by a dissolver stirrer into PMMA resin. The optical properties (refractive index, transmission) are determined as a function of the nanoparticle content. Compared to the pure polymer, the refractive index of the modified composite, measured at 633 nm, is increased by 0.001 and 0.004 at 0.1 wt% and 0.7 wt%, respectively. A similar tendency is observed at 1550 nm. The transmission in the near infrared (NIR) is similar to that of PMMA up to a content of 0.3 wt%. At higher nanoparticle contents transmission is reduced. The reduction in transmission is due to the presence of agglomerates larger then 1/10 of the applied wavelength, confirmed by TEM. The concept of incorporating inorganic/organic hybrid nanoparticles with intrinsic high refractive index in polymer matrices is very promising. A suitable effect in refractive index for application of ceramic nanoparticle/polymer nanocomposites as polymer waveguides could be observed even with low particle concentration.
Development of a Simple Sintering Law for Fractal Aggregates Composed of Unequal Sized Primary Particles
Authors: Hawa Takumi , Zachariah Michael R 
Published: April 2011

ABSTRACTSintering of silicon nanoparticle chain aggregates composed of unequal sized primary particles are investigated using molecular dynamics (MD) simulations at 1500 K. We consider straight chain aggregates consisting of up to 40 2.5 and 5.4 nm primary particles. The sintering time increases with increase in the total volume of the chain aggregate or with increase in the exposed initial surface area of the chain. A mathematical model was developed to describe the dynamics of sintering of such chain aggregates. The model is a power law modification of the Frenkel sintering equation with the Koch-Friedlander model to include primary particle size dependence. We found that the particle size effect is a local process, and important only at the initial stage of the sintering. Thus, the effect is not significant when the aggregate becomes large. The model is amenable for use in aerosol models that might include sintering effects.
White cast iron of network morphology-its formation and properties
Authors: Lan Yip Yeuk , Chuen Leung Ching , Ming Fuk Chung , Wah Mok Siu , Wing Kui Hin 
Published: April 2011

ABSTRACTA white cast iron of composition Fe81C14Si5 can be cast into a nanostructure with network morphology by a fluxing technique. The conventional morphology of white cast iron, which is brittle, is eutectic. The mechanical behavior of network white cast iron is attractive. Hardness tests indicate that its average hardness value is ∼770 HV. The indentations made during hardness tests have no cracks. A stylus surface profiler was employed to study the surface profile at and near the indentations. The studies indicate that there are severe plastic flows, but without cracks.
Homoepitaxial Growth of Vertical Si Nanowires on Si(100) Substrate using Anodic Aluminum Oxide Template
Authors: Shimizu Tomohiro , Xie Tian , Schmidt Volker , Nishikawa Jo , Shingubara Shoso , Senz Stephan , Goesele Ulrich 
Published: April 2011

ABSTRACTHomo-epitaxial growth of Si nanowires on Si (100) substrate was accomplished using a combination of anodic aluminum oxide (AAO) template and Vapor-Liquid-Solid (VLS) growth. We prepared two types of AAO template for epitaxial growth of Si nanowires.We observed vertically grown epitaxial Si (100) nanowires in the AAO template. In addition, after leaving filled pores, Si nanowires changed their growth direction from [100] to <111>. This result shows that the walls of the pores forced the growth direction of Si nanowires parallel to the direction of the pores, and after complete filling, the growth direction changes to that of the Si nanowires on a bare Si substrate.
Interplay between Morphology and Surface Transport in Nanopatterns Produced by Ion-Beam Sputtering
Authors: Cuerno Rodolfo , Muñoz-García Javier , Castro Mario , Gago Raúl , Vázquez Luis 
Published: April 2011

ABSTRACTA “hydrodynamic” model has been proposed to describe nanopattern formation and dynamics on amorphous surfaces eroded by ion-beam sputtering (IBS), that relates to descriptions of pattern formation in macroscopic systems such as aeolian sand dunes. At variance with previous continuum models of the morphology of ion-sputtered surfaces, the dynamics of the species that diffuse along the surface is coupled in a natural way to that of the surface height. We report recent results for this model, considering normal and oblique ion incidence, for both fixed and rotating targets, and include comparison to recent experiments on silicon. Effective interface equations can be obtained, that generalize the anisotropic Kuramoto-Sivashinshy equation through additional conserved Kardar-Parisi-Zhang type nonlinear terms. In general dot or ripple patterns form, that later evolve exhibiting complex nonlinear dynamics. Thus, we observe interrupted coarsening behavior such that, for normal incidence, domains of hexagonally ordered structures appear, that compare favorably with those obtained in many experiments of nanodot formation by IBS. In other parameter regions, this short-range ordered patterns coexist with long range disorder and kinetic roughening. For oblique incidence, a ripple pattern is generically obtained that also shows interrupted coarsening and other nonlinear features like non-uniform transverse motion, again reproducing experimental observations.
Fabrication of SnO2 Nano Patterns Using Surface Relief Grating
Authors: Yan Fadong , Li Lian , Huh Pilho , Wang Yanping , Samuelson Lynne A , Kumar Jayant 
Published: April 2011

ABSTRACTNano- and micro-structured SnO2 has been widely utilized as gas sensors. These SnO2 based gas sensors are often made by chemical etching, vapor deposition or lithography. Here we report a facile and vacuum-free technique to fabricate large area one-dimensional periodic SnO2 nano arrays using surface relief grating created on azobenzene functionalized polymer thin films as template. Atomic force microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy characterizations confirmed the successful fabrication of SnO2 nano arrays. The fabricated SnO2 structure exhibited the same periodicity as the template with a width of a few hundred nanometers.
Reversible Nanoscale Local Wettability Modifications by Thermochemcial Nanolithography
Authors: Wang Debin , Okada Takashi , Szoszkiewicz Robert , Jones Simon C , Lucas Marcel , Lee Jungchul , King William P , Marder Seth R , Riedo Elisa 
Published: April 2011

ABSTRACTRecently, the development of a versatile thermochemical nanolithography (TCNL) technique has been reported. It allows simultaneous control of the local chemistry and topography of thin polymer films. This technique can pattern sub 15 nm chemical and topographical features at the rate of 1.4 mm per second by inducing thermally-activated chemical reactions by means of a heated atomic force microscope (AFM) tip. TCNL is achievable in different environments and can easily be adapted to a variety of substrates and chemical functionalities. Here, we demonstrate that a thin polymer film can be chemically modified twice using TCNL to tune its wettability. We are able to write hydrophilic nanopatterns over a hydrophobic polymer surface upon a first step heating and then revert back to hydrophobic surface by a second step heating. This write-read-overwrite capability is particularly useful in data storage application and complex nanofluidic device design.
Electrostatic-Directed Deposition of Nanoparticles on a Field Generating Substrate
Authors: Tsai De-Hao , Hawa Takumi , Kan Hung-Chih , Phaneuf Raymond J , Zachariah Michael R 
Published: April 2011

ABSTRACTIn this paper we develop a Brownian dynamics model applied to position metal nanoparticles from the gas phase onto electrostatic-patterns generated by biasing P-N junction substrates. Brownian motion and fluid convection of nanoparticles, as well as the interactions between the charged nanoparticles and the patterned substrate, including electrostatic force, image force and van der Waals force, are accounted for in the simulation. Using both experiment and simulation we have investigated the effects of the particle size, electric field intensity, and the convective flow on coverage selectivity. Coverage selectivity is most sensitive to electric field, which is controlled by the applied reverse bias voltage across the p-n junction. A non-dimensional analysis of the competition between the electrostatic and diffusion force is found to provide a means to collapse a wide range of process operating conditions and an effective indicator or process performance.