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Sample records for 3d nanostructured metal

  1. Direct laser writing of 3D polymer micro/nanostructures on metallic surfaces

    NASA Astrophysics Data System (ADS)

    Rekštytė, Sima; Žukauskas, Albertas; Purlys, Vytautas; Gordienko, Yuri; Malinauskas, Mangirdas

    2013-04-01

    Spectra of fields for applications of polymeric 3D micro/nanostructures are rapidly widening thus demanding the development of versatile precise and efficient fabrication methods that can be used to process a variety of materials and could be implemented to form tiny devices on a variety of surfaces without influencing their structural quality. We present the latest results obtained using laser lithography approach: 3D polymeric structures with submicrometer spatial resolution on different opaque surfaces such as semiconductors (Si) and various metals (Cr, Al, Fe and Ti). The photostructuring was performed using a range of photosensitive materials such as acrylate based AKRE23, acrylated biodegradable PEG-DA-258, epoxy based mr-NIL 6000, hybrid organic-inorganic SZ2080 and Ormocore b59.

  2. Synthesis of 3D nanostructured metal alloy of immiscible materials induced by megahertz-repetition femtosecond laser pulses.

    PubMed

    Kiani, Amirkianoosh; Waraich, Palneet Singh; Venkatakrishnan, Krishnan; Tan, Bo

    2012-01-01

    : In this work, we have proposed a concept for the generation of three-dimensional (3D) nanostructured metal alloys of immiscible materials induced by megahertz-frequency ultrafast laser pulses. A mixture of two microparticle materials (aluminum and nickel oxide) and nickel oxide microparticles coated onto an aluminum foil have been used in this study. After laser irradiation, three different types of nanostructure composites have been observed: aluminum embedded in nickel nuclei, agglomerated chain of aluminum and nickel nanoparticles, and finally, aluminum nanoparticles grown on nickel microparticles. In comparison with current nanofabrication methods which are used only for one-dimensional nanofabrication, this technique enables us to fabricate 3D nanostructured metal alloys of two or more nanoparticle materials with varied composite concentrations under various predetermined conditions. This technique can lead to promising solutions for the fabrication of 3D nanostructured metal alloys in applications such as fuel-cell energy generation and development of custom-designed, functionally graded biomaterials and biocomposites. PMID:22999219

  3. Guided Evolution of Bulk Metallic Glass Nanostructures: A Platform for Designing 3D Electrocatalytic Surfaces.

    PubMed

    Doubek, Gustavo; Sekol, Ryan C; Li, Jinyang; Ryu, Won-Hee; Gittleson, Forrest S; Nejati, Siamak; Moy, Eric; Reid, Candy; Carmo, Marcelo; Linardi, Marcelo; Bordeenithikasem, Punnathat; Kinser, Emily; Liu, Yanhui; Tong, Xiao; Osuji, Chinedum O; Schroers, Jan; Mukherjee, Sundeep; Taylor, André D

    2016-03-01

    Electrochemical devices such as fuel cells, electrolyzers, lithium-air batteries, and pseudocapacitors are expected to play a major role in energy conversion/storage in the near future. Here, it is demonstrated how desirable bulk metallic glass compositions can be obtained using a combinatorial approach and it is shown that these alloys can serve as a platform technology for a wide variety of electrochemical applications through several surface modification techniques. PMID:26689722

  4. 3D Printed Block Copolymer Nanostructures

    ERIC Educational Resources Information Center

    Scalfani, Vincent F.; Turner, C. Heath; Rupar, Paul A.; Jenkins, Alexander H.; Bara, Jason E.

    2015-01-01

    The emergence of 3D printing has dramatically advanced the availability of tangible molecular and extended solid models. Interestingly, there are few nanostructure models available both commercially and through other do-it-yourself approaches such as 3D printing. This is unfortunate given the importance of nanotechnology in science today. In this…

  5. The Physics and Applications of a 3D Plasmonic Nanostructure

    NASA Astrophysics Data System (ADS)

    Terranova, Brandon B.

    In this work, the dynamics of electromagnetic field interactions with free electrons in a 3D metallic nanostructure is evaluated theoretically. This dissertation starts by reviewing the relevant fundamentals of plasmonics and modern applications of plasmonic systems. Then, motivated by the need to have a simpler way of understanding the surface charge dynamics on complex plasmonic nanostructures, a new plasmon hybridization tree method is introduced. This method provides the plasmonicist with an intuitive way to determine the response of free electrons to incident light in complex nanostructures within the electrostatic regime. Next, a novel 3D plasmonic nanostructure utilizing reflective plasmonic coupling is designed to perform biosensing and plasmonic tweezing applications. By applying analytical and numerical methods, the effectiveness of this nanostructure at performing these applications is determined from the plasmonic response of the nanostructure to an excitation beam of coherent light. During this analysis, it was discovered that under certain conditions, this 3D nanostructure exhibits a plasmonic Fano resonance resulting from the interference of an in-plane dark mode and an out-of-plane bright mode. In evaluating this nanostructure for sensing changes in the local dielectric environment, a figure of merit of 68 is calculated, which is competitive with current localized surface plasmon resonance refractometric sensors. By evaluating the Maxwell stress tensor on a test particle in the vicinity of the nanostructure, it was found that under the right conditions, this plasmonic nanostructure design is capable of imparting forces greater than 10.5 nN on dielectric objects of nanoscale dimensions. The results obtained in these studies provides new routes to the design and engineering of 3D plasmonic nanostructures and Fano resonances in these systems. In addition, the nanostructure presented in this work and the design principles it utilizes have shown

  6. 3D nanostructures fabricated by advanced stencil lithography.

    PubMed

    Yesilkoy, F; Flauraud, V; Rüegg, M; Kim, B J; Brugger, J

    2016-03-01

    This letter reports on a novel fabrication method for 3D metal nanostructures using high-throughput nanostencil lithography. Aperture clogging, which occurs on the stencil membranes during physical vapor deposition, is leveraged to create complex topographies on the nanoscale. The precision of the 3D nanofabrication method is studied in terms of geometric parameters and material types. The versatility of the technique is demonstrated by various symmetric and chiral patterns made of Al and Au. PMID:26884085

  7. 3D nanostructures fabricated by advanced stencil lithography

    NASA Astrophysics Data System (ADS)

    Yesilkoy, F.; Flauraud, V.; Rüegg, M.; Kim, B. J.; Brugger, J.

    2016-02-01

    This letter reports on a novel fabrication method for 3D metal nanostructures using high-throughput nanostencil lithography. Aperture clogging, which occurs on the stencil membranes during physical vapor deposition, is leveraged to create complex topographies on the nanoscale. The precision of the 3D nanofabrication method is studied in terms of geometric parameters and material types. The versatility of the technique is demonstrated by various symmetric and chiral patterns made of Al and Au.

  8. 3D visualization of polymer nanostructure

    SciTech Connect

    Werner, James H

    2009-01-01

    Soft materials and structured polymers are extremely useful nanotechnology building blocks. Block copolymers, in particular, have served as 2D masks for nanolithography and 3D scaffolds for photonic crystals, nanoparticle fabrication, and solar cells. F or many of these applications, the precise 3 dimensional structure and the number and type of defects in the polymer is important for ultimate function. However, directly visualizing the 3D structure of a soft material from the nanometer to millimeter length scales is a significant technical challenge. Here, we propose to develop the instrumentation needed for direct 3D structure determination at near nanometer resolution throughout a nearly millimeter-cubed volume of a soft, potentially heterogeneous, material. This new capability will be a valuable research tool for LANL missions in chemistry, materials science, and nanoscience. Our approach to soft materials visualization builds upon exciting developments in super-resolution optical microscopy that have occurred over the past two years. To date, these new, truly revolutionary, imaging methods have been developed and almost exclusively used for biological applications. However, in addition to biological cells, these super-resolution imaging techniques hold extreme promise for direct visualization of many important nanostructured polymers and other heterogeneous chemical systems. Los Alamos has a unique opportunity to lead the development of these super-resolution imaging methods for problems of chemical rather than biological significance. While these optical methods are limited to systems transparent to visible wavelengths, we stress that many important functional chemicals such as polymers, glasses, sol-gels, aerogels, or colloidal assemblies meet this requirement, with specific examples including materials designed for optical communication, manipulation, or light-harvesting Our Research Goals are: (1) Develop the instrumentation necessary for imaging materials

  9. 3D vertical nanostructures for enhanced infrared plasmonics.

    PubMed

    Malerba, Mario; Alabastri, Alessandro; Miele, Ermanno; Zilio, Pierfrancesco; Patrini, Maddalena; Bajoni, Daniele; Messina, Gabriele C; Dipalo, Michele; Toma, Andrea; Proietti Zaccaria, Remo; De Angelis, Francesco

    2015-01-01

    The exploitation of surface plasmon polaritons has been mostly limited to the visible and near infrared range, due to the low frequency limit for coherent plasmon excitation and the reduction of confinement on the metal surface for lower energies. In this work we show that 3D--out of plane--nanostructures can considerably increase the intrinsic quality of the optical output, light confinement and electric field enhancement factors, also in the near and mid-infrared. We suggest that the physical principle relies on the combination of far field and near field interactions between neighboring antennas, promoted by the 3D out-of-plane geometry. We first analyze the changes in the optical behavior, which occur when passing from a single on-plane nanostructure to a 3D out-of-plane configuration. Then we show that by arranging the nanostructures in periodic arrays, 3D architectures can provide, in the mid-IR, a much stronger plasmonic response, compared to that achievable with the use of 2D configurations, leading to higher energy harvesting properties and improved Q-factors, with bright perspective up to the terahertz range. PMID:26552340

  10. 3D vertical nanostructures for enhanced infrared plasmonics

    PubMed Central

    Malerba, Mario; Alabastri, Alessandro; Miele, Ermanno; Zilio, Pierfrancesco; Patrini, Maddalena; Bajoni, Daniele; Messina, Gabriele C.; Dipalo, Michele; Toma, Andrea; Proietti Zaccaria, Remo; De Angelis, Francesco

    2015-01-01

    The exploitation of surface plasmon polaritons has been mostly limited to the visible and near infrared range, due to the low frequency limit for coherent plasmon excitation and the reduction of confinement on the metal surface for lower energies. In this work we show that 3D - out of plane - nanostructures can considerably increase the intrinsic quality of the optical output, light confinement and electric field enhancement factors, also in the near and mid-infrared. We suggest that the physical principle relies on the combination of far field and near field interactions between neighboring antennas, promoted by the 3D out-of-plane geometry. We first analyze the changes in the optical behavior, which occur when passing from a single on-plane nanostructure to a 3D out-of-plane configuration. Then we show that by arranging the nanostructures in periodic arrays, 3D architectures can provide, in the mid-IR, a much stronger plasmonic response, compared to that achievable with the use of 2D configurations, leading to higher energy harvesting properties and improved Q-factors, with bright perspective up to the terahertz range. PMID:26552340

  11. A method to fabricate disconnected silver nanostructures in 3D.

    PubMed

    Vora, Kevin; Kang, SeungYeon; Mazur, Eric

    2012-01-01

    The standard nanofabrication toolkit includes techniques primarily aimed at creating 2D patterns in dielectric media. Creating metal patterns on a submicron scale requires a combination of nanofabrication tools and several material processing steps. For example, steps to create planar metal structures using ultraviolet photolithography and electron-beam lithography can include sample exposure, sample development, metal deposition, and metal liftoff. To create 3D metal structures, the sequence is repeated multiple times. The complexity and difficulty of stacking and aligning multiple layers limits practical implementations of 3D metal structuring using standard nanofabrication tools. Femtosecond-laser direct-writing has emerged as a pre-eminent technique for 3D nanofabrication.(1,2) Femtosecond lasers are frequently used to create 3D patterns in polymers and glasses.(3-7) However, 3D metal direct-writing remains a challenge. Here, we describe a method to fabricate silver nanostructures embedded inside a polymer matrix using a femtosecond laser centered at 800 nm. The method enables the fabrication of patterns not feasible using other techniques, such as 3D arrays of disconnected silver voxels.(8) Disconnected 3D metal patterns are useful for metamaterials where unit cells are not in contact with each other,(9) such as coupled metal dot(10,11)or coupled metal rod(12,13) resonators. Potential applications include negative index metamaterials, invisibility cloaks, and perfect lenses. In femtosecond-laser direct-writing, the laser wavelength is chosen such that photons are not linearly absorbed in the target medium. When the laser pulse duration is compressed to the femtosecond time scale and the radiation is tightly focused inside the target, the extremely high intensity induces nonlinear absorption. Multiple photons are absorbed simultaneously to cause electronic transitions that lead to material modification within the focused region. Using this approach, one can

  12. Shape control in wafer-based aperiodic 3D nanostructures

    NASA Astrophysics Data System (ADS)

    Jeong, Hyeon-Ho; Mark, Andrew G.; Gibbs, John G.; Reindl, Thomas; Waizmann, Ulrike; Weis, Jürgen; Fischer, Peer

    2014-06-01

    Controlled local fabrication of three-dimensional (3D) nanostructures is important to explore and enhance the function of single nanodevices, but is experimentally challenging. We present a scheme based on e-beam lithography (EBL) written seeds, and glancing angle deposition (GLAD) grown structures to create nanoscale objects with defined shapes but in aperiodic arrangements. By using a continuous sacrificial corral surrounding the features of interest we grow isolated 3D nanostructures that have complex cross-sections and sidewall morphology that are surrounded by zones of clean substrate.

  13. Study of morphology effects on magnetic interactions and band gap variations for 3d late transition metal bi-doped ZnO nanostructures by hybrid DFT calculations

    SciTech Connect

    Datta, Soumendu Baral, Sayan; Mookerjee, Abhijit; Kaphle, Gopi Chandra

    2015-08-28

    Using density functional theory (DFT) based electronic structure calculations, the effects of morphology of semiconducting nanostructures on the magnetic interaction between two magnetic dopant atoms as well as a possibility of tuning band gaps have been studied in the case of the bi-doped (ZnO){sub 24} nanostructures with the impurity dopant atoms of the 3d late transition metals—Mn, Fe, Co, Ni, and Cu. To explore the morphology effect, three different structures of the host (ZnO){sub 24} nano-system, having different degrees of spatial confinement, have been considered: a two dimensional nanosheet, a one dimensional nanotube, and a finite cage-shaped nanocluster. The present study employs hybrid density functional theory to accurately describe the electronic structure of all the systems. It is shown here that the magnetic coupling between the two dopant atoms remains mostly anti-ferromagnetic in the course of changing the morphology from the sheet geometry to the cage-shaped geometry of the host systems, except for the case of energetically most stable bi-Mn doping, which shows a transition from ferromagnetic to anti-ferromagnetic coupling with decreasing aspect ratio of the host system. The effect of the shape change, however, has a significant effect on the overall band gap variations of both the pristine as well as all the bi-doped systems, irrespective of the nature of the dopant atoms and provides a means for easy tunability of their optoelectronic properties.

  14. 3D molding of hierarchical micro- and nanostructures

    NASA Astrophysics Data System (ADS)

    Farshchian, Bahador; Hurst, Steven M.; Lee, Jaejong; Park, Sunggook

    2011-03-01

    We show a simple and effective process to produce large area, hierarchical 3D micro- and nanostructures via a modified hot embossing process, which we name 3D molding. The 3D molding process takes advantage of both a hard mold from hot embossing and the flexibility of a thin, elastomeric intermediate stamp from soft lithography. Using this method, we have demonstrated the formation of various micro- and nanostructures in non-planar microscale structures including microchannels and step surfaces. The ability to produce micro/nanopatterns within microchannels will have potential applications in bioanalytic micro/nanofluidic devices by allowing for the manipulation of a broader range of surface properties and thus control over surface interactions with biomaterials flowing through the microfluidic channels.

  15. Laser printing of 3D metallic interconnects

    NASA Astrophysics Data System (ADS)

    Beniam, Iyoel; Mathews, Scott A.; Charipar, Nicholas A.; Auyeung, Raymond C. Y.; Piqué, Alberto

    2016-04-01

    The use of laser-induced forward transfer (LIFT) techniques for the printing of functional materials has been demonstrated for numerous applications. The printing gives rise to patterns, which can be used to fabricate planar interconnects. More recently, various groups have demonstrated electrical interconnects from laser-printed 3D structures. The laser printing of these interconnects takes place through aggregation of voxels of either molten metal or of pastes containing dispersed metallic particles. However, the generated 3D structures do not posses the same metallic conductivity as a bulk metal interconnect of the same cross-section and length as those formed by wire bonding or tab welding. An alternative is to laser transfer entire 3D structures using a technique known as lase-and-place. Lase-and-place is a LIFT process whereby whole components and parts can be transferred from a donor substrate onto a desired location with one single laser pulse. This paper will describe the use of LIFT to laser print freestanding, solid metal foils or beams precisely over the contact pads of discrete devices to interconnect them into fully functional circuits. Furthermore, this paper will also show how the same laser can be used to bend or fold the bulk metal foils prior to transfer, thus forming compliant 3D structures able to provide strain relief for the circuits under flexing or during motion from thermal mismatch. These interconnect "ridges" can span wide gaps (on the order of a millimeter) and accommodate height differences of tens of microns between adjacent devices. Examples of these laser printed 3D metallic bridges and their role in the development of next generation electronics by additive manufacturing will be presented.

  16. Thermomechanical properties of 3d transition metals

    SciTech Connect

    Karaoglu, B.; Rahman, S.M.M. . Dept. of Physics)

    1994-05-15

    The authors have investigated the density variation of the Einstein temperatures and elastic constants of the 3d transition metals. In this respect they have employed the transition metal (TM) pair potentials involving the sp contribution with an appropriate exchange and correlation function, the d-band broadening contribution and the d-band hybridization term. These calculations are aimed at testing the TM pair potentials in generating the quasilocal and local thermomechanical properties.

  17. Ames Lab 101: 3D Metals Printer

    SciTech Connect

    Ott, Ryan

    2014-02-13

    To meet one of the biggest energy challenges of the 21st century - finding alternatives to rare-earth elements and other critical materials - scientists will need new and advanced tools. The Critical Materials Institute at the U.S. Department of Energy's Ames Laboratory has a new one: a 3D printer for metals research. 3D printing technology, which has captured the imagination of both industry and consumers, enables ideas to move quickly from the initial design phase to final form using materials including polymers, ceramics, paper and even food. But the Critical Materials Institute (CMI) will apply the advantages of the 3D printing process in a unique way: for materials discovery.

  18. Ames Lab 101: 3D Metals Printer

    ScienceCinema

    Ott, Ryan

    2014-06-04

    To meet one of the biggest energy challenges of the 21st century - finding alternatives to rare-earth elements and other critical materials - scientists will need new and advanced tools. The Critical Materials Institute at the U.S. Department of Energy's Ames Laboratory has a new one: a 3D printer for metals research. 3D printing technology, which has captured the imagination of both industry and consumers, enables ideas to move quickly from the initial design phase to final form using materials including polymers, ceramics, paper and even food. But the Critical Materials Institute (CMI) will apply the advantages of the 3D printing process in a unique way: for materials discovery.

  19. Nanostructured Pluronic hydrogels as bioinks for 3D bioprinting.

    PubMed

    Müller, Michael; Becher, Jana; Schnabelrauch, Matthias; Zenobi-Wong, Marcy

    2015-09-01

    Bioprinting is an emerging technology in the field of tissue engineering as it allows the precise positioning of biologically relevant materials in 3D, which more resembles the native tissue in our body than current homogenous, bulk approaches. There is however a lack of materials to be used with this technology and materials such as the block copolymer Pluronic have good printing properties but do not allow long-term cell culture. Here we present an approach called nanostructuring to increase the biocompatibility of Pluronic gels at printable concentrations. By mixing acrylated with unmodified Pluronic F127 it was possible to maintain the excellent printing properties of Pluronic and to create stable gels via UV crosslinking. By subsequent elution of the unmodified Pluronic from the crosslinked network we were able to increase the cell viability of encapsulated chondrocytes at day 14 from 62% for a pure acrylated Pluronic hydrogel to 86% for a nanostructured hydrogel. The mixed Pluronic gels also showed good printability when cells where included in the bioink. The nanostructured gels were, with a compressive modulus of 1.42 kPa, mechanically weak, but we were able to increase the mechanical properties by the addition of methacrylated hyaluronic acid. Our nanostructuring approach enables Pluronic hydrogels to have the desired set of properties in all stages of the bioprinting process. PMID:26260872

  20. Freestanding 3D mesoporous Co₃O₄@carbon foam nanostructures for ethanol gas sensing.

    PubMed

    Li, Lei; Liu, Minmin; He, Shuijian; Chen, Wei

    2014-08-01

    Metal oxide materials have been widely used as gas-sensing platforms, and their sensing performances are largely dependent on the morphology and surface structure. Here, freestanding flower-like Co3O4 nanostructures supported on three-dimensional (3D) carbon foam (Co3O4@CF) were successfully synthesized by a facile and low-cost hydrothermal route and annealing procedure. The morphology and structure of the nanocomposites were studied by X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, and scanning electron microscopy (SEM). The SEM characterizations showed that the skeleton of the porous carbon foam was fully covered by flower-like Co3O4 nanostructures. Moreover, each Co3O4 nanoflower is composed of densely packed nanoneedles with a length of ~10 μm, which can largely enhance the surface area (about 286.117 m(2)/g) for ethanol sensing. Gas sensor based on the as-synthesized 3D Co3O4@CF nanostructures was fabricated to study the sensing performance for ethanol at a temperature range from 180 to 360 °C. Due to the 3D porous structure and the improvement in sensing surface/interface, the Co3O4@CF nanostructure exhibited enhanced sensing performance for ethanol detection with low resistance, fast response and recovery time, high sensitivity, and limit of detection as low as 15 ppm at 320 °C. The present study shows that such novel 3D metal oxide/carbon hybrid nanostructures are promising platforms for gas sensing. PMID:25011608

  1. 3D modeling of metallic grain growth

    SciTech Connect

    George, D.; Carlson, N.; Gammel, J.T.; Kuprat, A.

    1999-06-01

    This paper will describe simulating metallic grain growth using the Gradient Weighted Moving Finite Elements code, GRAIN3D. The authors also describe the set of mesh topology change operations developed to respond to changes in the physical topology such as the collapse of grains and to maintain uniform calculational mesh quality. Validation of the method is demonstrated by comparison to analytic calculations. The authors present results of multigrain simulations where grain boundaries evolve by mean curvature motion and include results which incorporate grain boundary orientation dependence.

  2. Electrocatalysts: Guided Evolution of Bulk Metallic Glass Nanostructures: A Platform for Designing 3D Electrocatalytic Surfaces (Adv. Mater. 10/2016).

    PubMed

    Doubek, Gustavo; Sekol, Ryan C; Li, Jinyang; Ryu, Won-Hee; Gittleson, Forrest S; Nejati, Siamak; Moy, Eric; Reid, Candy; Carmo, Marcelo; Linardi, Marcelo; Bordeenithikasem, Punnathat; Kinser, Emily; Liu, Yanhui; Tong, Xiao; Osuji, Chinedum O; Schroers, Jan; Mukherjee, Sundeep; Taylor, André D

    2016-03-01

    On page 1940, A. D. Taylor and co-workers demonstrate nanoporous bicontinuous structures using controlled structural evolution of metallic glass. By using techniques such as dealloying, galvanic replacement, and under-potential deposition, bulk-metallic-glass alloys can be pushed beyond their compositional limitations and tuned for a wide variety of interfacial and electrochemical reactions. Examples are illustrated for hydrogen and methanol oxidation, as well as oxygen reduction reactions. PMID:26947938

  3. Spin fluctuations in 3d paramagnetic metals

    NASA Astrophysics Data System (ADS)

    Wysocki, Aleksander; Kutepov, Andrey; Antropov, Vladimir

    Spin fluctuations (SFs) in 3d paramagnetic metals were investigated using the linear response formalism within the time dependent density functional theory. An efficient scheme of frequency integration using the Matsubara technique has been implemented and tested. The SFs spectrum in 3d paramagnets is analyzed in real and reciprocal spaces as a function of frequency and temperature. For all materials the SFs are characterized by the coexistence of low and high energy branches which originate from different regions of the Brillouin zone. The low-energy ones can be measured by neutron scattering experiments while the high-energy SFs appear to be more localized. Further, we studied the nature of square of fluctuating magnetic moment in these materials. This work was supported, in part, by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy (DOE), and by the Office of Basic Energy Science, Division of Materials Science and Engineering. The research was performed at Ames Laboratory, which is operated for the U.S. DOE by Iowa State University under contract # DE-AC02-07CH11358.

  4. Nanostructured pseudocapacitive materials decorated 3D graphene foam electrodes for next generation supercapacitors

    NASA Astrophysics Data System (ADS)

    Patil, Umakant; Lee, Su Chan; Kulkarni, Sachin; Sohn, Ji Soo; Nam, Min Sik; Han, Suhyun; Jun, Seong Chan

    2015-04-01

    Nowadays, advancement in performance of proficient multifarious electrode materials lies conclusively at the core of research concerning energy storage devices. To accomplish superior capacitance performance the requirements of high capacity, better cyclic stability and good rate capability can be expected from integration of electrochemical double layer capacitor based carbonaceous materials (high power density) and pseudocapacitive based metal hydroxides/oxides or conducting polymers (high energy density). The envisioned three dimensional (3D) graphene foams are predominantly advantageous to extend potential applicability by offering a large active surface area and a highly conductive continuous porous network for fast charge transfer with decoration of nanosized pseudocapacitive materials. In this article, we review the latest methodologies and performance evaluation for several 3D graphene based metal oxides/hydroxides and conducting polymer electrodes with improved electrochemical properties for next-generation supercapacitors. The most recent research advancements of our and other groups in the field of 3D graphene based electrode materials for supercapacitors are discussed. To assess the studied materials fully, a careful interpretation and rigorous scrutiny of their electrochemical characteristics is essential. Auspiciously, both nano-structuration as well as confinement of metal hydroxides/oxides and conducting polymers onto a conducting porous 3D graphene matrix play a great role in improving the performance of electrodes mainly due to: (i) active material access over large surface area with fast charge transportation; (ii) synergetic effect of electric double layer and pseudocapacitive based charge storing.

  5. X-ray microscopy for in situ characterization of 3D nanostructural evolution in the laboratory

    NASA Astrophysics Data System (ADS)

    Hornberger, Benjamin; Bale, Hrishikesh; Merkle, Arno; Feser, Michael; Harris, William; Etchin, Sergey; Leibowitz, Marty; Qiu, Wei; Tkachuk, Andrei; Gu, Allen; Bradley, Robert S.; Lu, Xuekun; Withers, Philip J.; Clarke, Amy; Henderson, Kevin; Cordes, Nikolaus; Patterson, Brian M.

    2015-09-01

    X-ray microscopy (XRM) has emerged as a powerful technique that reveals 3D images and quantitative information of interior structures. XRM executed both in the laboratory and at the synchrotron have demonstrated critical analysis and materials characterization on meso-, micro-, and nanoscales, with spatial resolution down to 50 nm in laboratory systems. The non-destructive nature of X-rays has made the technique widely appealing, with potential for "4D" characterization, delivering 3D micro- and nanostructural information on the same sample as a function of sequential processing or experimental conditions. Understanding volumetric and nanostructural changes, such as solid deformation, pore evolution, and crack propagation are fundamental to understanding how materials form, deform, and perform. We will present recent instrumentation developments in laboratory based XRM including a novel in situ nanomechanical testing stage. These developments bridge the gap between existing in situ stages for micro scale XRM, and SEM/TEM techniques that offer nanometer resolution but are limited to analysis of surfaces or extremely thin samples whose behavior is strongly influenced by surface effects. Several applications will be presented including 3D-characterization and in situ mechanical testing of polymers, metal alloys, composites and biomaterials. They span multiple length scales from the micro- to the nanoscale and different mechanical testing modes such as compression, indentation and tension.

  6. A Process for Topographically Selective Deposition on 3D Nanostructures by Ion Implantation.

    PubMed

    Kim, Woo-Hee; Minaye Hashemi, Fatemeh Sadat; Mackus, Adriaan J M; Singh, Joseph; Kim, Yeongin; Bobb-Semple, Dara; Fan, Yin; Kaufman-Osborn, Tobin; Godet, Ludovic; Bent, Stacey F

    2016-04-26

    Area-selective atomic layer deposition (AS-ALD) is attracting increasing interest because of its ability to enable both continued dimensional scaling and accurate pattern placement for next-generation nanoelectronics. Here we report a strategy for depositing material onto three-dimensional (3D) nanostructures with topographic selectivity using an ALD process with the aid of an ultrathin hydrophobic surface layer. Using ion implantation of fluorocarbons (CFx), a hydrophobic interfacial layer is formed, which in turn causes significant retardation of nucleation during ALD. We demonstrate the process for Pt ALD on both blanket and 2D patterned substrates. We extend the process to 3D structures, demonstrating that this method can achieve selective anisotropic deposition, selectively inhibiting Pt deposition on deactivated horizontal regions while ensuring that only vertical surfaces are decorated during ALD. The efficacy of the approach for metal oxide ALD also shows promise, though further optimization of the implantation conditions is required. The present work advances practical applications that require area-selective coating of surfaces in a variety of 3D nanostructures according to their topographical orientation. PMID:26950397

  7. Direct laser writing of 3D micro/nanostructures on opaque surfaces

    NASA Astrophysics Data System (ADS)

    Rekštytė, Sima; Žukauskas, Albertas; Purlys, Vytautas; Gordienko, Yuri; Malinauskas, Mangirdas

    2012-06-01

    Spectra of fields for applications of polymeric 3D micro/nanostructures is rapidly widening thus demanding the development of versatile precise and efficient fabrication methods that can be used to process a variety of materials and could be implemented to form tiny devices on a variety of surfaces without influencing their structural quality. We present the latest results obtained using laser lithography approach: 3D polymeric structures with submicrometer spatial resolution on different opaque surfaces such as semiconductors (Si) and various metals (Cr, Al, Fe, Ti). The photostructuring was performed using a range of photosensitive materials such as acrylate based AKRE23, acrylated biodegradable PEG-DA-258, epoxy based mr-NIL 6000, hybrid organic-inorganic SZ2080 and Ormocore b59.

  8. 3D hierarchical walnut-like CuO nanostructures: Preparation, characterization and their efficient catalytic activity for CO oxidation

    NASA Astrophysics Data System (ADS)

    Yao, Weitang; Zhang, Yujuan; Duan, Tao; Zhu, Wenkun; Yi, Zao; Cui, Xudong

    2016-07-01

    In this work, 3D hierarchical walnut-shaped, 2D nanosheet and 3D microspheres single phase CuO nanostructures are functioning as catalysts and supporting materials, differing from the conventional ways. The novel nanostructures were synthesized via hydrothermal method under a stainless steel autoclave. The as-prepared materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and H2 temperature-programmed reduction (H2-TPR). The walnut-shaped structures with high O/Cu atomic ratio (1.22) exhibit high oxygen adsorption capacity and greatly enhanced catalytic activity. These results will be enrich the techniques for tuning the morphologies of metal oxide micro/nanostructures and open a new field in catalytic applications.

  9. 3D printing of liquid metals as fugitive inks for fabrication of 3D microfluidic channels.

    PubMed

    Parekh, Dishit P; Ladd, Collin; Panich, Lazar; Moussa, Khalil; Dickey, Michael D

    2016-05-21

    This paper demonstrates a simple method to fabricate 3D microchannels and microvasculature at room temperature by direct-writing liquid metal as a sacrificial template. The formation of a surface oxide skin on the low-viscosity liquid metal stabilizes the shape of the printed metal for planar and out-of-plane structures. The printed structures can be embedded in a variety of soft (e.g. elastomeric) and rigid (e.g. thermoset) polymers. Both acid and electrochemical reduction are capable of removing the oxide skin that forms on the metal, which destabilizes the ink so that it withdraws from the encapsulating material due to capillary forces, resulting in nearly full recovery of the fugitive ink at room temperature. Whereas conventional fabrication procedures typically confine microchannels to 2D planes, the geometry of the printed microchannels can be varied from a simple 2D network to complex 3D architectures without using lithography. The method produces robust monolithic structures without the need for any bonding or assembling techniques that often limit the materials of construction of conventional microchannels. Removing select portions of the metal leaves behind 3D metal features that can be used as antennas, interconnects, or electrodes for interfacing with lab-on-a-chip devices. This paper describes the capabilities and limitations of this simple process. PMID:27025537

  10. Surface 3D nanostructuring by tightly focused laser pulse: simulations by Lagrangian code and molecular dynamics

    NASA Astrophysics Data System (ADS)

    Inogamov, Nail A.; Zhakhovsky, Vasily V.

    2016-02-01

    There are many important applications in which the ultrashort diffraction-limited and therefore tightly focused laser pulses irradiates metal films mounted on dielectric substrate. Here we present the detailed picture of laser peeling and 3D structure formation of the thin (relative to a depth of a heat affected zone in the bulk targets) gold films on glass substrate. The underlying physics of such diffraction-limited laser peeling was not well understood previously. Our approach is based on a physical model which takes into consideration the new calculations of the two-temperature (2T) equation of state (2T EoS) and the two-temperature transport coefficients together with the coupling parameter between electron and ion subsystems. The usage of the 2T EoS and the kinetic coefficients is required because absorption of an ultrashort pulse with duration of 10-1000 fs excites electron subsystem of metal and transfers substance into the 2T state with hot electrons (typical electron temperatures 1-3 eV) and much colder ions. It is shown that formation of submicrometer-sized 3D structures is a result of the electron-ion energy transfer, melting, and delamination of film from substrate under combined action of electron and ion pressures, capillary deceleration of the delaminated liquid metal or semiconductor, and ultrafast freezing of molten material. We found that the freezing is going in non-equilibrium regime with strongly overcooled liquid phase. In this case the Stefan approximation is non-applicable because the solidification front speed is limited by the diffusion rate of atoms in the molten material. To solve the problem we have developed the 2T Lagrangian code including all this reach physics in. We also used the high-performance combined Monte- Carlo and molecular dynamics code for simulation of surface 3D nanostructuring at later times after completion of electron-ion relaxation.

  11. 3-D aluminum nanostructure with microhole array synthesized by femtosecond laser radiation for enhanced light extinction

    PubMed Central

    2013-01-01

    This article presents 3-D aluminum micro-nanostructures for enhanced light absorption. Periodic microhole arrays were created by firing a train of femtosecond laser pulses at megahertz pulse frequency onto the surface of an aluminum target at ambient conditions. The laser trains ablated the target surface and created microholes leading to the generation of deposited nanostructures inside and around the microholes. These micro-nanostructures showed enhanced light absorption, which is attributed to surface plasmonics induced by the generation of both nano- and microstructures. These micro-nanostructures may be promising for solar cell applications. PMID:24225364

  12. Quantitative Reconstructions of 3D Chemical Nanostructures in Nanowires.

    PubMed

    Rueda-Fonseca, P; Robin, E; Bellet-Amalric, E; Lopez-Haro, M; Den Hertog, M; Genuist, Y; André, R; Artioli, A; Tatarenko, S; Ferrand, D; Cibert, J

    2016-03-01

    Energy dispersive X-ray spectrometry is used to extract a quantitative 3D composition profile of heterostructured nanowires. The analysis of hypermaps recorded along a limited number of projections, with a preliminary calibration of the signal associated with each element, is compared to the intensity profiles calculated for a model structure with successive shells of circular, elliptic, or faceted cross sections. This discrete tomographic technique is applied to II-VI nanowires grown by molecular beam epitaxy, incorporating ZnTe and CdTe and their alloys with Mn and Mg, with typical size down to a few nanometers and Mn or Mg content as low as 10%. PMID:26837636

  13. Quantitative 3D electromagnetic field determination of 1D nanostructures from single projection.

    PubMed

    Phatak, C; de Knoop, L; Houdellier, F; Gatel, C; Hÿtch, M J; Masseboeuf, A

    2016-05-01

    One-dimensional (1D) nanostructures have been regarded as the most promising building blocks for nanoelectronics and nanocomposite material systems as well as for alternative energy applications. Although they result in confinement of a material, their properties and interactions with other nanostructures are still very much three-dimensional (3D) in nature. In this work, we present a novel method for quantitative determination of the 3D electromagnetic fields in and around 1D nanostructures using a single electron wave phase image, thereby eliminating the cumbersome acquisition of tomographic data. Using symmetry arguments, we have reconstructed the 3D magnetic field of a nickel nanowire as well as the 3D electric field around a carbon nanotube field emitter, from one single projection. The accuracy of quantitative values determined here is shown to be a better fit to the physics at play than the value obtained by conventional analysis. Moreover the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures. PMID:26998702

  14. Method for making a single-step etch mask for 3D monolithic nanostructures.

    PubMed

    Grishina, D A; Harteveld, C A M; Woldering, L A; Vos, W L

    2015-12-18

    Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to etch three-dimensional monolithic nanostructures using only CMOS-compatible processes. The mask is written in a hard-mask layer that is deposited on two adjacent inclined surfaces of a Si wafer. By projecting in a single step two different 2D patterns within one 3D mask on the two inclined surfaces, the mutual alignment between the patterns is ensured. Thereby after the mask pattern is defined, the etching of deep pores in two oblique directions yields a three-dimensional structure in Si. As a proof of concept we demonstrate 3D mask fabrication for three-dimensional diamond-like photonic band gap crystals in silicon. The fabricated crystals reveal a broad stop gap in optical reflectivity measurements. We propose how 3D nanostructures with five different Bravais lattices can be realized, namely cubic, tetragonal, orthorhombic, monoclinic and hexagonal, and demonstrate a mask for a 3D hexagonal crystal. We also demonstrate the mask for a diamond-structure crystal with a 3D array of cavities. In general, the 2D patterns on the different surfaces can be completely independently structured and still be in perfect mutual alignment. Indeed, we observe an alignment accuracy of better than 3.0 nm between the 2D mask patterns on the inclined surfaces, which permits one to etch well-defined monolithic 3D nanostructures. PMID:26581317

  15. Method for making a single-step etch mask for 3D monolithic nanostructures

    NASA Astrophysics Data System (ADS)

    Grishina, D. A.; Harteveld, C. A. M.; Woldering, L. A.; Vos, W. L.

    2015-12-01

    Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to etch three-dimensional monolithic nanostructures using only CMOS-compatible processes. The mask is written in a hard-mask layer that is deposited on two adjacent inclined surfaces of a Si wafer. By projecting in a single step two different 2D patterns within one 3D mask on the two inclined surfaces, the mutual alignment between the patterns is ensured. Thereby after the mask pattern is defined, the etching of deep pores in two oblique directions yields a three-dimensional structure in Si. As a proof of concept we demonstrate 3D mask fabrication for three-dimensional diamond-like photonic band gap crystals in silicon. The fabricated crystals reveal a broad stop gap in optical reflectivity measurements. We propose how 3D nanostructures with five different Bravais lattices can be realized, namely cubic, tetragonal, orthorhombic, monoclinic and hexagonal, and demonstrate a mask for a 3D hexagonal crystal. We also demonstrate the mask for a diamond-structure crystal with a 3D array of cavities. In general, the 2D patterns on the different surfaces can be completely independently structured and still be in perfect mutual alignment. Indeed, we observe an alignment accuracy of better than 3.0 nm between the 2D mask patterns on the inclined surfaces, which permits one to etch well-defined monolithic 3D nanostructures.

  16. Coherent control near metallic nanostructures

    SciTech Connect

    Efimov, Ilya; Efimov, Anatoly

    2008-01-01

    We study coherent control in the vicinity of metallic nanostructures. Unlike in the case of control in gas or liquid phase, the collective response of electrons in a metallic nanostructure can significantly enhance different frequency components of the control field. This enhancement strongly depends on the geometry of the nanostructure and can substantially modify the temporal profile of the local control field. The changes in the amplitude and phase of the control field near the nanostructure are studied using linear response theory. The inverse problem of finding the external electromagnetic field to generate the desired local control field is considered and solved.

  17. Enhancing surface interactions with colon cancer cells on a transferrin-conjugated 3D nanostructured substrate.

    PubMed

    Banerjee, Shashwat S; Paul, Debjani; Bhansali, Sujit G; Aher, Naval D; Jalota-Badhwar, Archana; Khandare, Jayant

    2012-06-11

    A transferrin-conjugated PEG-Fe(3) O(4) nanostructured matrix is developed to explore cellular responses in terms of enhanced cell adhesion, specific interactions between ligands in the matrix and molecular receptors on the cell membrane, comparison of cell shapes on 2D and 3D surfaces, and effect of polymer architecture on cell adhesion. Integration of such advanced synthetic nanomaterials into a functionalized 3D matrix to control cell behavior on surfaces will have implications in nanomedicine. PMID:22434693

  18. Arc Discharge Synthesis and Photoluminescence of 3D Feather-like AlN Nanostructures

    NASA Astrophysics Data System (ADS)

    Yang, Sl; Gao, Rs; Niu, Pl; Zou, Zy; Yu, Rh

    2011-12-01

    A complex three-dimensional (3D) feather-like AlN nanostructure was synthesized by a direct reaction of high-purity Al granules with nitrogen using an arc discharge method. By adjusting the discharge time, a coral-like nanostructure, which evolved from the feather-like nanostructure, has also been observed. The novel 3D feather-like AlN nanostructure has a hierarchical dendritic structure, which means that the angle between the trunk stem and its branch is always about 30° in any part of the structure. The fine branches on the surface of the feather-like nanostructure have shown a uniform fish scale shape, which are about 100 nm long, 10 nm thick and several tens of nanometers in width. An alternate growth model has been proposed to explain the novel nanostructure. The spectrum of the feather-like products shows a strong blue emission band centered at 438 nm (2.84 eV), which indicates their potential application as blue light-emitting diodes.

  19. A 3D insight on the catalytic nanostructuration of few-layer graphene

    PubMed Central

    Melinte, G.; Florea, I.; Moldovan, S.; Janowska, I.; Baaziz, W.; Arenal, R.; Wisnet, A.; Scheu, C.; Begin-Colin, S.; Begin, D.; Pham-Huu, C.; Ersen, O.

    2014-01-01

    The catalytic cutting of few-layer graphene is nowadays a hot topic in materials research due to its potential applications in the catalysis field and the graphene nanoribbons fabrication. We show here a 3D analysis of the nanostructuration of few-layer graphene by iron-based nanoparticles under hydrogen flow. The nanoparticles located at the edges or attached to the steps on the FLG sheets create trenches and tunnels with orientations, lengths and morphologies defined by the crystallography and the topography of the carbon substrate. The cross-sectional analysis of the 3D volumes highlights the role of the active nanoparticle identity on the trench size and shape, with emphasis on the topographical stability of the basal planes within the resulting trenches and channels, no matter the obstacle encountered. The actual study gives a deep insight on the impact of nanoparticles morphology and support topography on the 3D character of nanostructures built up by catalytic cutting. PMID:24916201

  20. Bimetallic core/shell nanoparticle-decorated 3D urchin-like hierarchical TiO2 nanostructures with magneto-responsive and decolorization characteristics

    NASA Astrophysics Data System (ADS)

    Xiang, Liqin; Liu, Shuo; Yin, Jianbo; Zhao, Xiaopeng

    2015-02-01

    The semiconductors decorated with noble metals or magnetic metals have attracted increasing attention due to multifunctional properties. In this article, we prepare novel bimetallic core/shell nanoparticle (Co@Au and Co@Ag)-decorated 3D urchin-like hierarchical TiO2 nanostructures through combining electroless plating and in situ replacement processes. The morphology and structure are characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, and a surface area analyzer. It demonstrates that Co@Au and Co@Ag nanoparticles are uniformly decorated on urchin-like TiO2 nanostructures. The composite nanostructures show not only surface plasmon absorption band from Au or Ag but also a magneto-responsive characteristic from Co. This allows composite nanostructures to exhibit advantages including enhanced decolorization efficiency compared to pure TiO2 nanostructures and facile separation from a solution by magnetic field.

  1. Quantitative prediction of 3D solution shape and flexibility of nucleic acid nanostructures.

    PubMed

    Kim, Do-Nyun; Kilchherr, Fabian; Dietz, Hendrik; Bathe, Mark

    2012-04-01

    DNA nanotechnology enables the programmed synthesis of intricate nanometer-scale structures for diverse applications in materials and biological science. Precise control over the 3D solution shape and mechanical flexibility of target designs is important to achieve desired functionality. Because experimental validation of designed nanostructures is time-consuming and cost-intensive, predictive physical models of nanostructure shape and flexibility have the capacity to enhance dramatically the design process. Here, we significantly extend and experimentally validate a computational modeling framework for DNA origami previously presented as CanDo [Castro,C.E., Kilchherr,F., Kim,D.-N., Shiao,E.L., Wauer,T., Wortmann,P., Bathe,M., Dietz,H. (2011) A primer to scaffolded DNA origami. Nat. Meth., 8, 221-229.]. 3D solution shape and flexibility are predicted from basepair connectivity maps now accounting for nicks in the DNA double helix, entropic elasticity of single-stranded DNA, and distant crossovers required to model wireframe structures, in addition to previous modeling (Castro,C.E., et al.) that accounted only for the canonical twist, bend and stretch stiffness of double-helical DNA domains. Systematic experimental validation of nanostructure flexibility mediated by internal crossover density probed using a 32-helix DNA bundle demonstrates for the first time that our model not only predicts the 3D solution shape of complex DNA nanostructures but also their mechanical flexibility. Thus, our model represents an important advance in the quantitative understanding of DNA-based nanostructure shape and flexibility, and we anticipate that this model will increase significantly the number and variety of synthetic nanostructures designed using nucleic acids. PMID:22156372

  2. Normal Metal Quasiparticle Traps in 3D-Transmon Qubits

    NASA Astrophysics Data System (ADS)

    Burkhart, Luke D.; Gao, Yvonne Y.; Wang, Chen; Serniak, Kyle; de Lange, Gijs; Chu, Yiwen; Vool, Uri; Frunzio, Luigi; Devoret, Michel H.; Catelani, Gianluigi; Glazman, Leonid I.; Schoelkopf, Robert J.

    Quasiparticles are a known source of decoherence in Josephson-junction based superconducting qubits. While equilibrium quasiparticles should not be present in devices operated at dilution refrigeration temperatures well below the superconducting energy gap, non-thermal quasiparticles have been observed in many different superconducting qubits, including 3D-transmons and fluxonium qubits. Vortices induced by applied magnetic fields have been shown to improve non-equilibrium quasiparticle decay rates and improve coherence times by creating regions of the superconductor with vanishing energy gap, which act as quasiparticle traps. We aim to further mitigate quasiparticle-induced limits on coherence by engineering strong trapping via the introduction of normal metal to the superconducting qubit. In this talk, we present recent results regarding normal metal quasiparticle traps in 3D-transmon qubits. Work supported by ARO, A*STAR.

  3. Metallic and 3D-printed dielectric helical terahertz waveguides.

    PubMed

    Vogt, Dominik Walter; Anthony, Jessienta; Leonhardt, Rainer

    2015-12-28

    We investigate guidance of Terahertz (THz) radiation in metallic and 3D-printed dielectric helical waveguides in the frequency range from 0.2 to 1 THz. Our experimental results obtained from THz time-domain spectroscopy (THz-TDS) measurements are in very good agreement with finite-difference time-domain (FDTD) simulations. We observe single-mode, low loss and low dispersive propagation of THz radiation in metallic helical waveguides over a broad bandwidth. The 3D-printed dielectric helical waveguides have substantially extended the bandwidth of a low loss dielectric tube waveguide as observed from the experimental and simulation results. The high flexibility of the helical design allows an easy incorporation into bench top THz devices. PMID:26832000

  4. Thin-dielectric-layer engineering for 3D nanostructure integration using an innovative planarization approach

    NASA Astrophysics Data System (ADS)

    Guerfi, Y.; Doucet, J. B.; Larrieu, G.

    2015-10-01

    Three-dimensional (3D) nanostructures are emerging as promising building blocks for a large spectrum of applications. One critical issue in integration regards mastering the thin, flat, and chemically stable insulating layer that must be implemented on the nanostructure network in order to build striking nano-architectures. In this letter, we report an innovative method for nanoscale planarization on 3D nanostructures by using hydrogen silesquioxane as a spin-on-glass (SOG) dielectric material. To decouple the thickness of the final layer from the height of the nanostructure, we propose to embed the nanowire network in the insulator layer by exploiting the planarizing properties of the SOG approach. To achieve the desired dielectric thickness, the structure is chemically etched back with a highly diluted solution to control the etch rate precisely. The roughness of the top surface was less than 2 nm. There were no surface defects and the planarity was excellent, even in the vicinity of the nanowires. This newly developed process was used to realize a multilevel stack architecture with sub-deca-nanometer-range layer thickness.

  5. Tuning and synthesis of metallic nanostructures by mechanical compression

    DOEpatents

    Fan, Hongyou; Li, Binsong

    2015-11-17

    The present invention provides a pressure-induced phase transformation process to engineer metal nanoparticle architectures and to fabricate new nanostructured materials. The reversible changes of the nanoparticle unit cell dimension under pressure allow precise control over interparticle separation in 2D or 3D nanoparticle assemblies, offering unique robustness for interrogation of both quantum and classic coupling interactions. Irreversible changes above a threshold pressure of about 8 GPa enables new nanostructures, such as nanorods, nanowires, or nanosheets.

  6. Magnetism In 3d Transition Metals at High Pressures

    SciTech Connect

    Iota, V

    2006-02-09

    This research project examined the changes in electronic and magnetic properties of transition metals and oxides under applied pressures, focusing on complex relationship between magnetism and phase stability in these correlated electron systems. As part of this LDRD project, we developed new measurement techniques and adapted synchrotron-based electronic and magnetic measurements for use in the diamond anvil cell. We have performed state-of-the-art X-ray spectroscopy experiments at the dedicated high-pressure beamline HP-CAT (Sector 16 Advanced Photon Source, Argonne National Laboratory), maintained in collaboration with of University of Nevada, Las Vegas and Geophysical Laboratory of The Carnegie Institution of Washington. Using these advanced measurements, we determined the evolution of the magnetic order in the ferromagnetic 3d transition metals (Fe, Co and Ni) under pressure, and found that at high densities, 3d band broadening results in diminished long range magnetic coupling. Our experiments have allowed us to paint a unified picture of the effects of pressure on the evolution of magnetic spin in 3d electron systems. The technical and scientific advances made during this LDRD project have been reported at a number of scientific meetings and conferences, and have been submitted for publication in technical journals. Both the technical advances and the physical understanding of correlated systems derived from this LDRD are being applied to research on the 4f and 5f electron systems under pressure.

  7. The fabrication of 3-D nanostructures by a low- voltage EBL

    NASA Astrophysics Data System (ADS)

    Oh, Seung Hun; Kim, Jae Gu; Kim, Chang Seok; Choi, Doo Sun; Chang, Sunghwan; Jeong, Myung Yung

    2011-02-01

    Three-dimensional (3-D) structures are used in many applications, including the fabrication of opto-electronic and bio-MEMS devices. Among the various fabrication techniques available for 3-D structures, nano imprint lithography (NIL) is preferred for producing nanoscale 3-D patterns because of its simplicity, relatively short processing time, and high manufacturing precision. For efficient replication in NIL, a precise 3-D stamp must be used as an imprinting tool. Hence, we attempted the fabrication of original 3-D master molds by low-voltage electron beam lithography (EBL). We then fabricated polydimethylsiloxane (PDMS) stamps from the original 3-D mold via replica molding with ultrasonic vibration.First, we experimentally analyzed the characteristics of low-voltage EBL in terms of various parameters such as resist thickness, acceleration voltage, aperture size, and baking temperature. From these e-beam exposure experiments, we found that the exposure depth and width were almost saturated at 3 kV or lesser, even when the electron dosage was increased. This allowed for the fabrication of various stepped 3-D nanostructures at a low voltage. In addition, by using line-dose EBL, V-groove patterns could be fabricated on a cured electron resist (ER) at a low voltage and low baking temperature. Finally, the depth variation could be controlled to within 10 nm through superposition exposure at 1 kV. From these results, we determined the optimum electron beam exposure conditions for the fabrication of various 3-D structures on ERs by low-voltage EBL. We then fabricated PDMS stamps via the replica molding process.

  8. Enhanced Gas Sensitivity and Selectivity on Aperture-Controllable 3D Interconnected Macro-Mesoporous ZnO Nanostructures.

    PubMed

    Liu, Jing; Huang, Huawen; Zhao, Heng; Yan, Xiaoting; Wu, Sijia; Li, Yu; Wu, Min; Chen, Lihua; Yang, Xiaoyu; Su, Bao-Lian

    2016-04-01

    Three-dimensional (3D) macro-mesoporous structures demonstrate effective performance for gas sensing. In this work, we have designed and successfully prepared aperture-controllable three-dimensional interconnected macro-mesoporous ZnO (3D-IMM-ZnO) nanostructures by template-based layer-by-layer filtration deposition. XRD, SEM, and TEM have been used to characterize the obtained hexagonal wurzite 3D-IMM-ZnO nanostructures. Owing to its special 3D interconnected hierarchically porous structure, the 3D-IMM-ZnO nanostructures exhibit excellent gas sensing performances toward acetone and methanol. The 3D-IMM-ZnO nanostructure with the largest macropore demonstrates the best gas sensitivity owing to its largest cavity providing enough space for gas diffusion. On the basis of the results and analyses, we propose that the synergistic effect of electron liberation and electron density of acetone and the special structure make the 3D-IMM-ZnO nanostructures demonstrate better gas sensing properties than many other porous ZnO nanostructures and preferred selectivity to acetone. PMID:26998736

  9. Correlated electron pseudopotentials for 3d-transition metals

    SciTech Connect

    Trail, J. R. Needs, R. J.

    2015-02-14

    A recently published correlated electron pseudopotentials (CEPPs) method has been adapted for application to the 3d-transition metals, and to include relativistic effects. New CEPPs are reported for the atoms Sc − Fe, constructed from atomic quantum chemical calculations that include an accurate description of correlated electrons. Dissociation energies, molecular geometries, and zero-point vibrational energies of small molecules are compared with all electron results, with all quantities evaluated using coupled cluster singles doubles and triples calculations. The CEPPs give better results in the correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature.

  10. Correlated electron pseudopotentials for 3d-transition metals

    NASA Astrophysics Data System (ADS)

    Trail, J. R.; Needs, R. J.

    2015-02-01

    A recently published correlated electron pseudopotentials (CEPPs) method has been adapted for application to the 3d-transition metals, and to include relativistic effects. New CEPPs are reported for the atoms Sc - Fe, constructed from atomic quantum chemical calculations that include an accurate description of correlated electrons. Dissociation energies, molecular geometries, and zero-point vibrational energies of small molecules are compared with all electron results, with all quantities evaluated using coupled cluster singles doubles and triples calculations. The CEPPs give better results in the correlated-electron calculations than Hartree-Fock-based pseudopotentials available in the literature.

  11. Self-Assembled 3D Flower-Like Nickel Hydroxide Nanostructures and Their Supercapacitor Applications.

    PubMed

    Parveen, Nazish; Cho, Moo Hwan

    2016-01-01

    Three-dimensional (3D) nanostructures have attracted considerable attention because of their high surface areas and unique properties which gives outstanding performance in catalysis and energy storage applications. This paper proposes the growth mechanism of 3D flower-like β-Ni(OH)2 constructed through a two dimensional sheet framework using a one-step oleylamine-assisted solvothermal approach, where oleylamine acts as the surfactant, co-solvent, stabilizer, and reducing agent. A detailed examination of the product morphology after various reaction times suggested that the self-assembly of flower occurs through a mechanism involving nucleation, Ostwald ripening, and recrystallization. The associated characterization revealed it to be pure β-Ni(OH)2 without any sign of contamination. The effect of the morphology (sheet to 3D flower-like β-Ni(OH)2) on the electrochemical supercapacitive behavior was assessed by cyclic voltammetry and galvanostatic charge-discharge tests. The results showed that 3D flower-like β-Ni(OH)2 exhibited better specific capacitance of ~1567 F g(-1) at a current density of 1 A g(-1) and retained ~25% capacitance at a high current density of 10 A g(-1) compared to the other reference materials. The superior electrochemical properties of the 3D flower-like β-Ni(OH)2 originate from their large specific surface area and unique structure. PMID:27251067

  12. Laser nanostructuring 3-D bioconstruction based on carbon nanotubes in a water matrix of albumin

    NASA Astrophysics Data System (ADS)

    Gerasimenko, Alexander Y.; Ichkitidze, Levan P.; Podgaetsky, Vitaly M.; Savelyev, Mikhail S.; Selishchev, Sergey V.

    2016-04-01

    3-D bioconstructions were created using the evaporation method of the water-albumin solution with carbon nanotubes (CNTs) by the continuous and pulsed femtosecond laser radiation. It is determined that the volume structure of the samples created by the femtosecond radiation has more cavities than the one created by the continuous radiation. The average diameter for multi-walled carbon nanotubes (MWCNTs) samples was almost two times higher (35-40 nm) than for single-walled carbon nanotubes (SWCNTs) samples (20-30 nm). The most homogenous 3-D bioconstruction was formed from MWCNTs by the continuous laser radiation. The hardness of such samples totaled up to 370 MPa at the nanoscale. High strength properties and the resistance of the 3-D bioconstructions produced by the laser irradiation depend on the volume nanotubes scaffold forming inside them. The scaffold was formed by the electric field of the directed laser irradiation. The covalent bond energy between the nanotube carbon molecule and the oxygen of the bovine serum albumin aminoacid residue amounts 580 kJ/mol. The 3-D bioconstructions based on MWCNTs and SWCNTs becomes overgrown with the cells (fibroblasts) over the course of 72 hours. The samples based on the both types of CNTs are not toxic for the cells and don't change its normal composition and structure. Thus the 3-D bioconstructions that are nanostructured by the pulsed and continuous laser radiation can be applied as implant materials for the recovery of the connecting tissues of the living body.

  13. Self-Assembled 3D Flower-Like Nickel Hydroxide Nanostructures and Their Supercapacitor Applications

    PubMed Central

    Parveen, Nazish; Cho, Moo Hwan

    2016-01-01

    Three-dimensional (3D) nanostructures have attracted considerable attention because of their high surface areas and unique properties which gives outstanding performance in catalysis and energy storage applications. This paper proposes the growth mechanism of 3D flower-like β-Ni(OH)2 constructed through a two dimensional sheet framework using a one-step oleylamine-assisted solvothermal approach, where oleylamine acts as the surfactant, co-solvent, stabilizer, and reducing agent. A detailed examination of the product morphology after various reaction times suggested that the self-assembly of flower occurs through a mechanism involving nucleation, Ostwald ripening, and recrystallization. The associated characterization revealed it to be pure β-Ni(OH)2 without any sign of contamination. The effect of the morphology (sheet to 3D flower-like β-Ni(OH)2) on the electrochemical supercapacitive behavior was assessed by cyclic voltammetry and galvanostatic charge-discharge tests. The results showed that 3D flower-like β-Ni(OH)2 exhibited better specific capacitance of ~1567 F g−1 at a current density of 1 A g−1 and retained ~25% capacitance at a high current density of 10 A g−1 compared to the other reference materials. The superior electrochemical properties of the 3D flower-like β-Ni(OH)2 originate from their large specific surface area and unique structure. PMID:27251067

  14. Self-Assembled 3D Flower-Like Nickel Hydroxide Nanostructures and Their Supercapacitor Applications

    NASA Astrophysics Data System (ADS)

    Parveen, Nazish; Cho, Moo Hwan

    2016-06-01

    Three-dimensional (3D) nanostructures have attracted considerable attention because of their high surface areas and unique properties which gives outstanding performance in catalysis and energy storage applications. This paper proposes the growth mechanism of 3D flower-like β-Ni(OH)2 constructed through a two dimensional sheet framework using a one-step oleylamine-assisted solvothermal approach, where oleylamine acts as the surfactant, co-solvent, stabilizer, and reducing agent. A detailed examination of the product morphology after various reaction times suggested that the self-assembly of flower occurs through a mechanism involving nucleation, Ostwald ripening, and recrystallization. The associated characterization revealed it to be pure β-Ni(OH)2 without any sign of contamination. The effect of the morphology (sheet to 3D flower-like β-Ni(OH)2) on the electrochemical supercapacitive behavior was assessed by cyclic voltammetry and galvanostatic charge-discharge tests. The results showed that 3D flower-like β-Ni(OH)2 exhibited better specific capacitance of ~1567 F g‑1 at a current density of 1 A g‑1 and retained ~25% capacitance at a high current density of 10 A g‑1 compared to the other reference materials. The superior electrochemical properties of the 3D flower-like β-Ni(OH)2 originate from their large specific surface area and unique structure.

  15. Assembly of one dimensional inorganic nanostructures into functional 2D and 3D architectures. Synthesis, arrangement and functionality.

    PubMed

    Joshi, Ravi K; Schneider, Jörg J

    2012-08-01

    This review will focus on the synthesis, arrangement, structural assembly, for current and future applications, of 1D nanomaterials (tubes, wires, rods) in 2D and 3D ordered arrangements. The ability to synthesize and arrange one dimensional nanomaterials into ordered 2D or 3D micro or macro sized structures is of utmost importance in developing new devices and applications of these materials. Micro and macro sized architectures based on such 1D nanomaterials (e.g. tubes, wires, rods) provide a platform to integrate nanostructures at a larger and thus manageable scale into high performance electronic devices like field effect transistors, as chemo- and biosensors, catalysts, or in energy material applications. Carbon based, metal oxide and metal based 1D arranged materials as well as hybrid or composite 1D materials of the latter provide a broad materials platform, offering a perspective for new entries into fascinating structures and future applications of such assembled architectures. These architectures allow bridging the gap between 1D nanostructures and the micro and macro world and are the basis for an assembly of 1D materials into higher hierarchy domains. This critical review is intended to provide an interesting starting point to view the current state of the art and show perspectives for future developments in this field. The emphasis is on selected nanomaterials and the possibilities for building three dimensional arrays starting from one dimensional building blocks. Carbon nanotubes, metal oxide nanotubes and nanowires (e.g. ZnO, TiO(2), V(2)O(5), Cu(2)O, NiO, Fe(2)O(3)), silicon and germanium nanowires, and group III-V or II-VI based 1D semiconductor nanostructures like GaS and GaN, pure metals as well as 1D hybrid materials and their higher organized architectures (foremost in 3D) will be focussed. These materials have been the most intensively studied within the last 5-10 years with respect to nano-micro integration aspects and their functional and

  16. Predicting the Electronic Properties of 3D, Million-atom Semiconductor nanostructure Architectures

    SciTech Connect

    Jack Dongarra; Stanimire Tomov

    2012-03-15

    This final report describes the work done by Jack Dongarra (University Distinguished Professor) and Stanimire Tomov (Research Scientist) related to the DOE project entitled Predicting the Electronic Properties of 3D, Million-Atom Semiconductor Nanostructure Architectures. In this project we addressed the mathematical methodology required to calculate the electronic and transport properties of large nanostructures with comparable accuracy and reliability to that of current ab initio methods. This capability is critical for further developing the field, yet it is missing in all the existing computational methods. Additionally, quantitative comparisons with experiments are often needed for a qualitative understanding of the physics, and for guiding the design of new nanostructures. We focused on the mathematical challenges of the project, in particular on solvers and preconditioners for large scale eigenvalue problems that occur in the computation of electronic states of large nanosystems. Usually, the states of interest lie in the interior of the spectrum and their computation poses great difficulties for existing algorithms. The electronic properties of a semiconductor nanostructure architecture can be predicted/determined by computing its band structure. Of particular importance are the 'band edge states' (electronic states near the energy gap) which can be computed from a properly defined interior eigenvalue problem. Our primary mathematics and computational challenge here has been to develop an efficient solution methodology for finding these interior states for very large systems. Our work has produced excellent results in terms of developing both new and extending current state-of-the-art techniques.

  17. Voltage controlled magnetism in 3d transitional metals

    NASA Astrophysics Data System (ADS)

    Wang, Weigang

    2015-03-01

    Despite having attracted much attention in multiferroic materials and diluted magnetic semiconductors, the impact of an electric field on the magnetic properties remains largely unknown in 3d transitional ferromagnets (FMs) until recent years. A great deal of effort has been focused on the voltage-controlled magnetic anisotropy (VCMA) effect where the modulation of anisotropy field is understood by the change of electron density among different d orbitals of FMs in the presence of an electric field. Here we demonstrate another approach to alter the magnetism by electrically controlling the oxidation state of the 3d FM at the FM/oxide interface. The thin FM film sandwiched between a heavy metal layer and a gate oxide can be reversibly changed from an optimally-oxidized state with a strong perpendicular magnetic anisotropy to a metallic state with an in-plane magnetic anisotropy, or to a fully-oxidized state with nearly zero magnetization, depending on the polarity and time duration of the applied electric fields. This is a voltage controlled magnetism (VCM) effect, where both the saturation magnetization and anisotropy field of the 3d FM layer can be simultaneously controlled by voltage in a non-volatile fashion. We will also discuss the impact of this VCM effect on magnetic tunnel junctions and spin Hall switching experiments. This work, in collaboration with C. Bi, Y.H. Liu, T. Newhouse-Illige, M. Xu, M. Rosales, J.W. Freeland, O. Mryasov, S. Zhang, and S.G.E. te Velthuis, was supported in part by NSF (ECCS-1310338) and by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA.

  18. Synthesis of various 3D porous gold-based alloy nanostructures with branched shapes.

    PubMed

    Swiatkowska-Warkocka, Zaneta; Pyatenko, Alexander; Koshizaki, Naoto; Kawaguchi, Kenji

    2016-12-01

    This paper presents a facile and flexible synthesis platform for various 3D porous gold-iron nanostructures based on selective laser heating of colloidal nanoparticles and selective acid treatment. The presented approach allows to create porous gold-based nanostructures with different morphologies. In addition, for the first time, our studies indicate that various nanoarchitectures (brain-like, flower-like, cage-like, or raspberry-like structures) can be obtained by varying the experimental conditions such as size of Au and Fe3O4 nanoparticles, solvent, laser fluence, and irradiation time. We believe that these porous structures will find immediate applications in catalysis and separations, where high surface area and magnetic properties are often simultaneously required. PMID:27565959

  19. Plasmonic spectroscopy of metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Ni, Weihai

    The study of the plasmonic spectroscopy of metallic nanostructures is of great interest in nanoscale optics and photonics. Metallic nanostructures exhibit rich optical and electrical properties due to their localized surface plasmons (LSPs, collective charge density oscillations that are confined to metallic nanostructures). They can be widely used in a variety of application areas, such as surface-enhanced Raman scattering (SERS), plasmonic sensing, and metal enhanced fluorescence (MEF). In this thesis, a systematic study on the plasmonic spectroscopy of metallic nanostructures has been presented, both theoretically and experimentally. I will first describe my studies on the plasmonic properties of metallic nanostructures. Specific approaches of modifying the sizes and shapes of Au nanorods have been developed for tailoring their plasmonic properties, including surface plasmon wavelength, absorption, scattering, and extinction cross sections. Single-particle dark-field imaging and spectroscopy have proved that the scattering intensity of overgrown nanorods is larger than that of shortened nanorods from the same starting nanorods. Finite-difference time-domain (FDTD) calculations further show that the scattering-to-extinction ratio increases linearly as a function of the diameter of Au nanorods with a fixed aspect ratio. To obtain a deep understanding on the shape dependence of the localized surface plasmon resonance, I have emplyed FDTD on both Au nanorods and Au nanobipyramids. The results show that, when excited at their LSP wavelengths, Au nanobipyramids exhibit a maximal electric field intensity enhancement that is 3--6 times that of Au nanorods. Au nanorods have been further assembled into chains (end-to-end) and stacks (side-by-side). FDTD calculations have been performed on both Au nanorod chains and stacks with varying gap distances to obtain the dependence of the plasmon shift on the gap distance, which is then used as a plasmonic ruler to estimate the

  20. Comprehensive nanostructure and defect analysis using a simple 3D light-scatter sensor.

    PubMed

    Herffurth, Tobias; Schröder, Sven; Trost, Marcus; Duparré, Angela; Tünnermann, Andreas

    2013-05-10

    Light scattering measurement and analysis is a powerful tool for the characterization of optical and nonoptical surfaces. A new 3D scatter measurement system based on a detector matrix is presented. A compact light-scatter sensor is used to characterize the scattering and nanostructures of surfaces and to identify the origins of anisotropic scattering features. The results from the scatter sensor are directly compared with white light interferometry to analyze surface defects as well as surface roughness and the corresponding scattering distributions. The scattering of surface defects is modeled based on the Kirchhoff integral equation and the approach of Beckmann for rough surfaces. PMID:23669841

  1. Metal nanoparticle direct inkjet printing for low-temperature 3D micro metal structure fabrication

    NASA Astrophysics Data System (ADS)

    Ko, Seung Hwan; Chung, Jaewon; Hotz, Nico; Nam, Koo Hyun; Grigoropoulos, Costas P.

    2010-12-01

    Inkjet printing of functional materials is a key technology toward ultra-low-cost, large-area electronics. We demonstrate low-temperature 3D micro metal structure fabrication by direct inkjet printing of metal nanoparticles (NPs) as a versatile, direct 3D metal structuring approach representing an alternative to conventional vacuum deposition and photolithographic methods. Metal NP ink was inkjet-printed to exploit the large melting temperature drop of the nanomaterial and the ease of the NP ink formulation. Parametric studies on the basic conditions for stable 3D inkjet printing of NP ink were carried out. Furthermore, diverse 3D metal microstructures, including micro metal pillar arrays, helices, zigzag and micro bridges were demonstrated and electrical characterization was performed. Since the process requires low temperature, it carries substantial potential for fabrication of electronics on a plastic substrate.

  2. Sustainable approach toward synthesis of green functional carbonaceous 3-D micro/nanostructures from biomass

    NASA Astrophysics Data System (ADS)

    Tavangar, Amirhossein; Tan, Bo; Venkatakrishnan, Krishnan

    2013-08-01

    This study proposes a novel technique to synthesize functional carbonaceous three-dimensional (3-D) micro/nanocompounds from agricultural by-products using femtosecond laser irradiation. Biowastes of rice husk and wheat straw are value-engineered to carbonaceous structures in a single-step process under ambient conditions. Our results demonstrate that by controlling the laser fluence, structures with a variety of different morphologies from nanostructures to microstructures can be achieved. Also, the results indicate that altering the laser processing parameters influences the chemical composition of the synthesized structures. This sustainable approach presents an important step towards synthesizing 3-D micro/nanofibrous compounds from biowaste materials. These structures, as-synthesized or as nanocomposite fillers, can have practical uses in electronic, sensing, biological, and environmental applications.

  3. Sustainable approach toward synthesis of green functional carbonaceous 3-D micro/nanostructures from biomass.

    PubMed

    Tavangar, Amirhossein; Tan, Bo; Venkatakrishnan, Krishnan

    2013-01-01

    This study proposes a novel technique to synthesize functional carbonaceous three-dimensional (3-D) micro/nanocompounds from agricultural by-products using femtosecond laser irradiation. Biowastes of rice husk and wheat straw are value-engineered to carbonaceous structures in a single-step process under ambient conditions. Our results demonstrate that by controlling the laser fluence, structures with a variety of different morphologies from nanostructures to microstructures can be achieved. Also, the results indicate that altering the laser processing parameters influences the chemical composition of the synthesized structures. This sustainable approach presents an important step towards synthesizing 3-D micro/nanofibrous compounds from biowaste materials. These structures, as-synthesized or as nanocomposite fillers, can have practical uses in electronic, sensing, biological, and environmental applications. PMID:23924310

  4. Metal oxide nanostructures with hierarchical morphology

    DOEpatents

    Ren, Zhifeng; Lao, Jing Yu; Banerjee, Debasish

    2007-11-13

    The present invention relates generally to metal oxide materials with varied symmetrical nanostructure morphologies. In particular, the present invention provides metal oxide materials comprising one or more metallic oxides with three-dimensionally ordered nanostructural morphologies, including hierarchical morphologies. The present invention also provides methods for producing such metal oxide materials.

  5. Sintering and ripening resistant noble metal nanostructures

    DOEpatents

    van Swol, Frank B; Song, Yujiang; Shelnutt, John A; Miller, James E; Challa, Sivakumar R

    2013-09-24

    Durable porous metal nanostructures comprising thin metal nanosheets that are metastable under some conditions that commonly produce rapid reduction in surface area due to sintering and/or Ostwald ripening. The invention further comprises the method for making such durable porous metal nanostructures. Durable, high-surface area nanostructures result from the formation of persistent durable holes or pores in metal nanosheets formed from dendritic nanosheets.

  6. Structure and magnetic exchange in heterometallic 3d-3d transition metal triethanolamine clusters.

    PubMed

    Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S

    2012-01-21

    Synthetic methods are described that have resulted in the formation of seven heterometallic complexes, all of which contain partially deprotonated forms of the ligand triethanolamine (teaH(3)). These compounds are [Mn(III)(4)Co(III)(2)Co(II)(2)O(2)(teaH(2))(2)(teaH)(0.82)(dea)(3.18)(O(2)CMe)(2)(OMe)(2)](BF(4))(2)(O(2)CMe)(2)·3.18MeOH·H(2)O (1), [Mn(II)(2)Mn(III)(2)Co(III)(2)(teaH)(4)(OMe)(2)(acac)(4)](NO(3))(2)·2MeOH (2), [Mn(III)(2)Ni(II)(4)(teaH)(4)(O(2)CMe)(6)]·2MeCN (3), [Mn(III)(2)Co(II)(2)(teaH)(2)(sal)(2)(acac)(2)(MeOH)(2)]·2MeOH (4), [Mn(II)(2)Fe(III)(2)(teaH)(2)(paa)(4)](NO(3))(2)·2MeOH·CH(2)Cl(2) (5), [Mn(II)Mn(III)(2)Co(III)(2)O(teaH)(2)(dea)(Iso)(OMe)(F)(2)(Phen)(2)](BF(4))(NO(3))·3MeOH (6) and [Mn(II)(2)Mn(III)Co(III)(2)(OH)(teaH)(3)(teaH(2))(acac)(3)](NO(3))(2)·3CH(2)Cl(2) (7). All of the compounds contain manganese, combined with 3d transition metal ions such as Fe, Co and Ni. The crystal structures are described and examples of 'rods', tetranuclear 'butterfly' and 'triangular' Mn(3) cluster motifs, flanked in some cases by diamagnetic cobalt(III) centres, are presented. Detailed DC and AC magnetic susceptibility and magnetization studies, combined with spin Hamiltonian analysis, have yielded J values and identified the spin ground states. In most cases, the energies of the low-lying excited states have also been obtained. The features of note include the 'inverse butterfly' spin arrangement in 2, 4 and 5. A S = 5/2 ground state occurs, for the first time, in the Mn(III)(2)Mn(II) triangular moiety within 6, the many other reported [Mn(3)O](6+) examples having S = ½ or 3/2 ground states. Compound 7 provides the first example of a Mn(II)(2)Mn(III) triangle, here within a pentanuclear Mn(3)Co(2) cluster. PMID:22113523

  7. Fabrication of solution processed 3D nanostructured CuInGaS₂ thin film solar cells.

    PubMed

    Chu, Van Ben; Cho, Jin Woo; Park, Se Jin; Hwang, Yun Jeong; Park, Hoo Keun; Do, Young Rag; Min, Byoung Koun

    2014-03-28

    In this study we demonstrate the fabrication of CuInGaS₂ (CIGS) thin film solar cells with a three-dimensional (3D) nanostructure based on indium tin oxide (ITO) nanorod films and precursor solutions (Cu, In and Ga nitrates in alcohol). To obtain solution processed 3D nanostructured CIGS thin film solar cells, two different precursor solutions were applied to complete gap filling in ITO nanorods and achieve the desirable absorber film thickness. Specifically, a coating of precursor solution without polymer binder material was first applied to fill the gap between ITO nanorods followed by deposition of the second precursor solution in the presence of a binder to generate an absorber film thickness of ∼1.3 μm. A solar cell device with a (Al, Ni)/AZO/i-ZnO/CdS/CIGS/ITO nanorod/glass structure was constructed using the CIGS film, and the highest power conversion efficiency was measured to be ∼6.3% at standard irradiation conditions, which was 22.5% higher than the planar type of CIGS solar cell on ITO substrate fabricated using the same precursor solutions. PMID:24569126

  8. Direct fabrication of complex 3D hierarchical nanostructures by reactive ion etching of hollow sphere colloidal crystals.

    PubMed

    Zhong, Kuo; Li, Jiaqi; Van Cleuvenbergen, Stijn; Clays, Koen

    2016-09-21

    Direct reactive ion etching (RIE) of hollow SiO2 sphere colloidal crystals (HSCCs) is employed as a facile, low-cost method to fabricate complex three-dimensional (3D) hierarchical nanostructures. These multilayered structures are gradually transformed into nanostructures of increasing complexity by controlling the etching time, without complicated procedures (no mask needed). The resulting 3D topologies are unique, and cannot be obtained through traditional approaches. The formation mechanism of these structures is explained in detail by geometrical modeling during the different etching stages, through shadow effects of the higher layers. SEM images confirm the modeled morphological changes. The nanostructures obtained by our approach show very fine features as small as ∼30 nm. Our approach opens new avenues to directly obtain complex 3D nanostructures from colloidal crystals and can find applications in sensing, templating, and catalysis where fine tuning the specific surface might be critical. PMID:27545098

  9. Ion Beam Etching: Replication of Micro Nano-structured 3D Stencil Masks

    SciTech Connect

    Weber, Patrick; Guibert, Edouard; Mikhailov, Serguei; Bruegger, Juergen; Villanueva, Guillermo

    2009-03-10

    Ion beam LIGA allows the etching of 3D nano-structures by direct writing with a nano-sized beam. However, this is a relatively time consuming process. We propose here another approach for etching structures on large surfaces and faster, compared to the direct writing process. This approach consists of replicating 3D structured masks, by scanning an unfocused ion beam. A polymer substrate is placed behind the mask, as in UV photolithography. But the main advantage is that the 3D structure of the mask can be replicated into the polymer. For that purpose, the masks (developped at LMIS1, EPFL) are made of a silicon nitride membrane 100 nm thick, on which 3D gold structures up to 200 nm thick, are deposited. The 3D Au structures are made with the nanostencil method, based on successive gold deposition. The IMA institute, from HE-Arc, owns a High Voltage Engineering 1.7 MV Tandetron with both solid and gaseous negative ion sources, able to generate ions from almost every chemical element in a broad range of energies comprised between 400 keV and 6.8 MeV. The beam composition and energy are chosen in such a way, that ions lose a significant fraction of their energy when passing through the thickest regions of the mask. Ions passing through thinner regions of the mask loose a smaller fraction of their energy and etch the polymer with larger thicknesses, allowing a replication of the mask into the polymer. For our trials, we have used a carbon beam with an energy of 500 keV. The beam was focussed to a diameter of 5 mm with solid slits, in order to avoid border effects and thus ensure a homogeneous dose distribution on the beam diameter. The feasibility of this technique has been demonstrated, allowing industrial applications for micro-mould fabrication, micro-fluidics and micro-optics.

  10. Engineering Magnetic Anisotropy in Nanostructured 3d and 4f Ferromagnets

    NASA Astrophysics Data System (ADS)

    Hsu, Chin-Jui

    Due to the increased demand for clean energy in recent years, there is a need for the scientific community to develop technology to harvest thermal energy which is ubiquitous but mostly wasted in our environment. However, there is still no efficient approach to harvest thermal energy to date. In this study, the theory of thermomagnetic energy harvesting is reviewed and unique applications of multiferroics (ferromagnetic plus ferroelectric) are introduced. Based on an efficiency analysis using experimentally measured magneto-thermal properties of 3d transitional and 4f rare earth ferromagnetic elements, the idea of using single domain ferromagnetic elements to obtain higher thermomagnetic conversion efficiencies is proposed. In order to fabricate a ferromagnetic single domain, the magnetic anisotropy of gadolinium (Gd) and nickel (Ni) is engineered at the nanoscale. Both thin films and nanostructures are fabricated and characterized with a focus on the change of magnetic anisotropy governed by shape, crystal structure, and strain. The fabrication processes include sputtering, e-beam lithography (writing and evaporation), and focused ion beam milling. Characterization techniques involving atomic/magnetic force microscopy, energy dispersive X-ray spectroscopy, magneto-optical Kerr effect magnetometry, superconducting quantum interference device magnetometry, scanning/transmission electron microscopy, and X-ray diffraction will also be discussed. Experimental results show that the magnetic domain structure of nanostructured Ni can be stably controlled with geometric constraints or by strain induced via electric field. The magnetic properties of nanostructured Gd, on the other hand, is sensitive to crystal structure. These results provide critical information toward the use of ferromagnetic nanostructures in thermomagnetic energy harvesting and multiferroic applications.

  11. Metal-carbon nanostructures

    SciTech Connect

    Puretzky, A.A.; Hettich, R.L.; Jin, Changming; Haufler, R.E.; Compton, R.N.; Tuinman, A.A.

    1993-12-31

    Ultrafine particles formed by XeCl laser photolysis of M(CO){sub 6}, M = V, Cr, Mo, and W, have been analyzed by Fourier transform mass spectrometry and other techniques. Novel metal carbide clusters, (MoC{sub 4}){sub n}, n = 1 {minus} 4 and (WC{sub 4}){sub m}, m = 1 {minus} 8, were detected and studied. The material produced by photolysis of V(CO){sub 6} shows a series of vanadium-oxygen clusters, V{sub x}O{sub 2x+2}, x = 2 {minus} 10. No clusters of any type were detected in the photolysis product of Cr(CO){sub 6}. Structures based on the experimental evidence are proposed and discussed in light of their chemical reactivity.

  12. Precision polymers and 3D DNA nanostructures: emergent assemblies from new parameter space.

    PubMed

    Serpell, Christopher J; Edwardson, Thomas G W; Chidchob, Pongphak; Carneiro, Karina M M; Sleiman, Hanadi F

    2014-11-01

    Polymer self-assembly and DNA nanotechnology have both proved to be powerful nanoscale techniques. To date, most attempts to merge the fields have been limited to placing linear DNA segments within a polydisperse block copolymer. Here we show that, by using hydrophobic polymers of a precisely predetermined length conjugated to DNA strands, and addressable 3D DNA prisms, we are able to effect the formation of unprecedented monodisperse quantized superstructures. The structure and properties of larger micelles-of-prisms were probed in depth, revealing their ability to participate in controlled release of their constituent nanostructures, and template light-harvesting energy transfer cascades, mediated through both the addressability of DNA and the controlled aggregation of the polymers. PMID:25325677

  13. CAD/CAM-designed 3D-printed electroanalytical cell for the evaluation of nanostructured gas-diffusion electrodes.

    PubMed

    Chervin, Christopher N; Parker, Joseph F; Nelson, Eric S; Rolison, Debra R; Long, Jeffrey W

    2016-04-29

    The ability to effectively screen and validate gas-diffusion electrodes is critical to the development of next-generation metal-air batteries and regenerative fuel cells. The limiting electrode in a classic two-terminal device such as a battery or fuel cell is difficult to discern without an internal reference electrode, but the flooded electrolyte characteristic of three-electrode electroanalytical cells negates the prime function of an air electrode-a void volume freely accessible to gases. The nanostructured catalysts that drive the energy-conversion reactions (e.g., oxygen reduction and evolution in the air electrode of metal-air batteries) are best evaluated in the electrode structure as-used in the practical device. We have designed, 3D-printed, and characterized an air-breathing, thermodynamically referenced electroanalytical cell that allows us to mimic the Janus arrangement of the gas-diffusion electrode in a metal-air cell: one face freely exposed to gases, the other wetted by electrolyte. PMID:26987282

  14. CAD/CAM-designed 3D-printed electroanalytical cell for the evaluation of nanostructured gas-diffusion electrodes

    NASA Astrophysics Data System (ADS)

    Chervin, Christopher N.; Parker, Joseph F.; Nelson, Eric S.; Rolison, Debra R.; Long, Jeffrey W.

    2016-04-01

    The ability to effectively screen and validate gas-diffusion electrodes is critical to the development of next-generation metal-air batteries and regenerative fuel cells. The limiting electrode in a classic two-terminal device such as a battery or fuel cell is difficult to discern without an internal reference electrode, but the flooded electrolyte characteristic of three-electrode electroanalytical cells negates the prime function of an air electrode—a void volume freely accessible to gases. The nanostructured catalysts that drive the energy-conversion reactions (e.g., oxygen reduction and evolution in the air electrode of metal-air batteries) are best evaluated in the electrode structure as-used in the practical device. We have designed, 3D-printed, and characterized an air-breathing, thermodynamically referenced electroanalytical cell that allows us to mimic the Janus arrangement of the gas-diffusion electrode in a metal-air cell: one face freely exposed to gases, the other wetted by electrolyte.

  15. Hollow metal nanostructures for enhanced plasmonics (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Genç, Aziz; Patarroyo, Javier; Sancho-Parramon, Jordi; Duchamp, Martial; Gonzalez, Edgar; Bastus, Neus G.; Houben, Lothar; Dunin-Borkowski, Rafal; Puntes, Victor F.; Arbiol, Jordi

    2016-03-01

    Complex metal nanoparticles offer a great playground for plasmonic nanoengineering, where it is possible to cover plasmon resonances from ultraviolet to near infrared by modifying the morphologies from solid nanocubes to nanoframes, multiwalled hollow nanoboxes or even nanotubes with hybrid (alternating solid and hollow) structures. We experimentally show that structural modifications, i.e. void size and final morphology, are the dominant determinants for the final plasmonic properties, while compositional variations allow us to get a fine tuning. EELS mappings of localized surface plasmon resonances (LSPRs) reveal an enhanced plasmon field inside the voids of hollow AuAg nanostructures along with a more homogeneous distributions of the plasmon fields around the nanostructures. With the present methodology and the appropriate samples we are able to compare the effects of hybridization at the nanoscale in hollow nanostructures. Boundary element method (BEM) simulations also reveal the effects of structural nanoengineering on plasmonic properties of hollow metal nanostructures. Possibility of tuning the LSPR properties of hollow metal nanostructures in a wide range of energy by modifying the void size/shell thickness is shown by BEM simulations, which reveals that void size is the dominant factor for tuning the LSPRs. As a proof of concept for enhanced plasmonic properties, we show effective label free sensing of bovine serum albumin (BSA) with some of our hollow nanostructures. In addition, the different plasmonic modes observed have also been studied and mapped in 3D.

  16. Laser Transfer of Metals and Metal Alloys for Digital Microfabrication of 3D Objects.

    PubMed

    Zenou, Michael; Sa'ar, Amir; Kotler, Zvi

    2015-09-01

    3D copper logos printed on epoxy glass laminates are demonstrated. The structures are printed using laser transfer of molten metal microdroplets. The example in the image shows letters of 50 µm width, with each letter being taller than the last, from a height of 40 µm ('s') to 190 µm ('l'). The scanning microscopy image is taken at a tilt, and the topographic image was taken using interferometric 3D microscopy, to show the effective control of this technique. PMID:25966320

  17. Plasmonic properties and applications of metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Zhen, Yurong

    Plasmonic properties and the related novel applications are studied on various types of metallic nano-structures in one, two, or three dimensions. For 1D nanostructure, the motion of free electrons in a metal-film with nanoscale thickness is confined in its normal dimension and free in the other two. Describing the free-electron motion at metal-dielectric surfaces, surface plasmon polariton (SPP) is an elementary excitation of such motions and is well known. When further perforated with periodic array of holes, periodicity will introduce degeneracy, incur energy-level splitting, and facilitate the coupling between free-space photon and SPP. We applied this concept to achieve a plasmonic perfect absorber. The experimentally observed reflection dip splitting is qualitatively explained by a perturbation theory based on the above concept. If confined in 2D, the nanostructures become nanowires that intrigue a broad range of research interests. We performed various studies on the resonance and propagation of metal nanowires with different materials, cross-sectional shapes and form factors, in passive or active medium, in support of corresponding experimental works. Finite- Difference Time-Domain (FDTD) simulations show that simulated results agrees well with experiments and makes fundamental mode analysis possible. Confined in 3D, the electron motions in a single metal nanoparticle (NP) leads to localized surface plasmon resonance (LSPR) that enables another novel and important application: plasmon-heating. By exciting the LSPR of a gold particle embedded in liquid, the excited plasmon will decay into heat in the particle and will heat up the surrounding liquid eventually. With sufficient exciting optical intensity, the heat transfer from NP to liquid will undergo an explosive process and make a vapor envelop: nanobubble. We characterized the size, pressure and temperature of the nanobubble by a simple model relying on Mie calculations and continuous medium assumption. A

  18. Arbitrary and Parallel Nanofabrication of 3D Metal Structures with Polymer Brush Resists.

    PubMed

    Chen, Chaojian; Xie, Zhuang; Wei, Xiaoling; Zheng, Zijian

    2015-12-01

    3D polymer brushes are reported for the first time as ideal resists for the alignment-free nanofabrication of complex 3D metal structures with sub-100 nm lateral resolution and sub-10 nm vertical resolution. Since 3D polymer brushes can be serially fabricated in parallel, this method is effective to generate arbitrary 3D metal structures over a large area at a high throughput. PMID:26439441

  19. Precise 3D printing of micro/nanostructures using highly conductive carbon nanotube-thiol-acrylate composites

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Xiong, W.; Jiang, L. J.; Zhou, Y. S.; Lu, Y. F.

    2016-04-01

    Two-photon polymerization (TPP) is of increasing interest due to its unique combination of truly three-dimensional (3D) fabrication capability and ultrahigh spatial resolution of ~40 nm. However, the stringent requirements of non-linear resins seriously limit the material functionality of 3D printing via TPP. Precise fabrication of 3D micro/nanostructures with multi-functionalities such as high electrical conductivity and mechanical strength is still a long-standing challenge. In this work, TPP fabrication of arbitrary 3D micro/nanostructures using multi-walled carbon nanotube (MWNT)-thiolacrylate (MTA) composite resins has been developed. Up to 0.2 wt% MWNTs have been incorporated into thiol-acrylate resins to form highly stable and uniform composite photoresists without obvious degradation for one week at room temperature. Various functional 3D micro/nanostructures including woodpiles, micro-coils, spiral-like photonic crystals, suspended micro-bridges, micro-gears and complex micro-cars have been successfully fabricated. The MTA composite resin offers significant enhancements in electrical conductivity and mechanical strength, and on the same time, preserving high optical transmittance and flexibility. Tightly controlled alignment of MWNTs and the strong anisotropy effect were confirmed. Microelectronic devices including capacitors and resistors made of the MTA composite polymer were demonstrated. The 3D micro/nanofabrication using the MTA composite resins enables the precise 3D printing of micro/nanostructures of high electrical conductivity and mechanical strength, which is expected to lead a wide range of device applications, including micro/nano-electromechanical systems (MEMS/NEMS), integrated photonics and 3D electronics.

  20. Strength, Deformation and Fracture in Metallic Nanostructures

    NASA Astrophysics Data System (ADS)

    Gu, Xun Wendy

    An understanding of the mechanics of nanoscale metals and semiconductors is necessary for the safe and prolonged operation of nanostructured devices from transistors to nanowire- based solar cells to miniaturized electrodes. This is a fascinating but challenging pursuit because mechanical properties that are size-invariant in conventional materials, such as strength, ductility and fracture behavior, can depend critically on sample size when materials are reduced to sub-micron dimensions. In this thesis, the effect of nanoscale sample size, microstructure and structural geometry on mechanical strength, deformation and fracture are explored for several classes of solid materials. Nanocrystalline platinum nano-cylinders with diameters of 60 nm to 1 μm and 12 nm sized grains are fabricated and tested in compression. We find that nano-sized metals containing few grains weaken as sample diameter is reduced relative to grain size due to a change from deformation governed by internal grains to surface grain governed deformation. Fracture at the nanoscale is explored by performing in-situ SEM tension tests on nanocrystalline platinum and amorphous, metallic glass nano-cylinders containing purposely introduced structural flaws. It is found that failure location, mechanism and strength are determined by the stress concentration with the highest local stress whether this is at the structural flaw or a microstructural feature. Principles of nano-mechanics are used to design and test mechanically robust hierarchical nanostructures with structural and electrochemical applications. 2-photon lithography and electroplating are used to fabricate 3D solid Cu octet meso-lattices with micron-scale features that exhibit strength higher than that of bulk Cu. An in-situ SEM lithiation stage is developed and used to simultaneously examine morphological and electrochemical changes in Si-coated Cu meso-lattices that are of interest as high energy capacity electrodes for Li-ion batteries.

  1. Laser nanolithography and chemical metalization for the manufacturing of 3D metallic interconnects

    NASA Astrophysics Data System (ADS)

    Jonavičius, Tomas; RekštytÄ--, Sima; Žukauskas, Albertas; Malinauskas, Mangirdas

    2014-03-01

    We present a developed method based on direct laser writing (DLW) and chemical metallization (CM) for microfabrication of three-dimensional (3D) metallic structures. Such approach enables manufacturing of free­-form electro conductive interconnects which can be used in integrated electric circuits such micro-opto-electro mechanical systems (MOEMS). The proposed technique employing ultrafast high repetition rate laser enables efficient fabrication of 3D microstructures on dielectric as well as conductive substrates. The produced polymer links out of organic-inorganic composite matrix after CM serve as interconnects of separate metallic contacts, their dimensions are: height 15μm, width 5μm, length 35-45 μm and could provide 300 nΩm resistivity measured in a macroscopic way. This proves the techniques potential for creating integrated 3D electric circuits at microscale.

  2. Laser Scanning Holographic Lithography for Flexible 3D Fabrication of Multi-Scale Integrated Nano-structures and Optical Biosensors

    PubMed Central

    Yuan, Liang (Leon); Herman, Peter R.

    2016-01-01

    Three-dimensional (3D) periodic nanostructures underpin a promising research direction on the frontiers of nanoscience and technology to generate advanced materials for exploiting novel photonic crystal (PC) and nanofluidic functionalities. However, formation of uniform and defect-free 3D periodic structures over large areas that can further integrate into multifunctional devices has remained a major challenge. Here, we introduce a laser scanning holographic method for 3D exposure in thick photoresist that combines the unique advantages of large area 3D holographic interference lithography (HIL) with the flexible patterning of laser direct writing to form both micro- and nano-structures in a single exposure step. Phase mask interference patterns accumulated over multiple overlapping scans are shown to stitch seamlessly and form uniform 3D nanostructure with beam size scaled to small 200 μm diameter. In this way, laser scanning is presented as a facile means to embed 3D PC structure within microfluidic channels for integration into an optofluidic lab-on-chip, demonstrating a new laser HIL writing approach for creating multi-scale integrated microsystems. PMID:26922872

  3. Laser Scanning Holographic Lithography for Flexible 3D Fabrication of Multi-Scale Integrated Nano-structures and Optical Biosensors.

    PubMed

    Yuan, Liang Leon; Herman, Peter R

    2016-01-01

    Three-dimensional (3D) periodic nanostructures underpin a promising research direction on the frontiers of nanoscience and technology to generate advanced materials for exploiting novel photonic crystal (PC) and nanofluidic functionalities. However, formation of uniform and defect-free 3D periodic structures over large areas that can further integrate into multifunctional devices has remained a major challenge. Here, we introduce a laser scanning holographic method for 3D exposure in thick photoresist that combines the unique advantages of large area 3D holographic interference lithography (HIL) with the flexible patterning of laser direct writing to form both micro- and nano-structures in a single exposure step. Phase mask interference patterns accumulated over multiple overlapping scans are shown to stitch seamlessly and form uniform 3D nanostructure with beam size scaled to small 200 μm diameter. In this way, laser scanning is presented as a facile means to embed 3D PC structure within microfluidic channels for integration into an optofluidic lab-on-chip, demonstrating a new laser HIL writing approach for creating multi-scale integrated microsystems. PMID:26922872

  4. Laser Scanning Holographic Lithography for Flexible 3D Fabrication of Multi-Scale Integrated Nano-structures and Optical Biosensors

    NASA Astrophysics Data System (ADS)

    Yuan, Liang (Leon); Herman, Peter R.

    2016-02-01

    Three-dimensional (3D) periodic nanostructures underpin a promising research direction on the frontiers of nanoscience and technology to generate advanced materials for exploiting novel photonic crystal (PC) and nanofluidic functionalities. However, formation of uniform and defect-free 3D periodic structures over large areas that can further integrate into multifunctional devices has remained a major challenge. Here, we introduce a laser scanning holographic method for 3D exposure in thick photoresist that combines the unique advantages of large area 3D holographic interference lithography (HIL) with the flexible patterning of laser direct writing to form both micro- and nano-structures in a single exposure step. Phase mask interference patterns accumulated over multiple overlapping scans are shown to stitch seamlessly and form uniform 3D nanostructure with beam size scaled to small 200 μm diameter. In this way, laser scanning is presented as a facile means to embed 3D PC structure within microfluidic channels for integration into an optofluidic lab-on-chip, demonstrating a new laser HIL writing approach for creating multi-scale integrated microsystems.

  5. 3D Epitaxy of Graphene nanostructures in the Matrix of Ag, Al and Cu

    NASA Astrophysics Data System (ADS)

    Salamanca-Riba, Lourdes; Isaacs, Romaine; Wuttig, Manfred; Lemieux, Melburne; Hu, Liangbing; Iftekhar, Jaim; Rashkeev, Sergey; Kukla, Maija; Rabin, Oded; Mansour, Azzam

    2015-03-01

    Graphene nanostructures in the form ribbons were embedded in the lattice of metals such as Ag, Cu, and Al in concentrations up to 36.4 at.%, 21.8 at% and 10.5 at.%, respectively. These materials are called covetics. Raman scattering from Ag and Al covetics indicate variations in the intensity of peaks at ~ 1,300 cm-1 and 1,600 cm-1 with position on the sample. These peaks are associated with the D (defects) and G (graphite E2g mode) peaks of graphitic carbon with sp2 bonding and reveal various degrees of imperfections in the graphene layers. First principles calculations of the dynamic matrix of Ag and Al covetics show bonding between C and the metal. EELS mapping of the C-K edge and high resolution lattice images show that the graphene-like regions form ribbons with epitaxial orientation with the metal lattice of Ag and Al. The temperature dependences of the resistivites of Ag and Cu covetics are similar to those of the pure metals with only slight increase in resistivity. Films of Cu covetic deposited by e-beam evaporation and PLD show higher transmittance and resistance to oxidation than pure metal films of the same thickness indicating that copper covetic films can be used for transparent electrodes. Funded by DARPA/ARL Grant No. W911NF-13-1-0058, and ONR Award No N000141410042.

  6. Synthesis of crystalline and amorphous, particle-agglomerated 3-D nanostructures of Al and Si oxides by femtosecond laser and the prediction of these particle sizes

    PubMed Central

    2012-01-01

    We report a single step technique of synthesizing particle-agglomerated, amorphous 3-D nanostructures of Al and Si oxides on powder-fused aluminosilicate ceramic plates and a simple novel method of wafer-foil ablation to fabricate crystalline nanostructures of Al and Si oxides at ambient conditions. We also propose a particle size prediction mechanism to regulate the size of vapor-condensed agglomerated nanoparticles in these structures. Size characterization studies performed on the agglomerated nanoparticles of fabricated 3-D structures showed that the size distributions vary with the fluence-to-threshold ratio. The variation in laser parameters leads to varying plume temperature, pressure, amount of supersaturation, nucleation rate, and the growth rate of particles in the plume. The novel wafer-foil ablation technique could promote the possibilities of fabricating oxide nanostructures with varying Al/Si ratio, and the crystallinity of these structures enhances possible applications. The fabricated nanostructures of Al and Si oxides could have great potentials to be used in the fabrication of low power-consuming complementary metal-oxide-semiconductor circuits and in Mn catalysts to enhance the efficiency of oxidation on ethylbenzene to acetophenone in the super-critical carbon dioxide. PMID:23140103

  7. 3D carbon/cobalt-nickel mixed-oxide hybrid nanostructured arrays for asymmetric supercapacitors.

    PubMed

    Zhu, Jianhui; Jiang, Jian; Sun, Zhipeng; Luo, Jingshan; Fan, Zhanxi; Huang, Xintang; Zhang, Hua; Yu, Ting

    2014-07-23

    The electrochemical performance of supercapacitors relies not only on the exploitation of high-capacity active materials, but also on the rational design of superior electrode architectures. Herein, a novel supercapacitor electrode comprising 3D hierarchical mixed-oxide nanostructured arrays (NAs) of C/CoNi3 O4 is reported. The network-like C/CoNi3 O4 NAs exhibit a relatively high specific surface area; it is fabricated from ultra-robust Co-Ni hydroxide carbonate precursors through glucose-coating and calcination processes. Thanks to their interconnected three-dimensionally arrayed architecture and mesoporous nature, the C/CoNi3 O4 NA electrode exhibits a large specific capacitance of 1299 F/g and a superior rate performance, demonstrating 78% capacity retention even when the discharge current jumps by 100 times. An optimized asymmetric supercapacitor with the C/CoNi3 O4 NAs as the positive electrode is fabricated. This asymmetric supercapacitor can reversibly cycle at a high potential of 1.8 V, showing excellent cycling durability and also enabling a remarkable power density of ∼13 kW/kg with a high energy density of ∼19.2 W·h/kg. Two such supercapacitors linked in series can simultaneously power four distinct light-emitting diode indicators; they can also drive the motor of remote-controlled model planes. This work not only presents the potential of C/CoNi3 O4 NAs in thin-film supercapacitor applications, but it also demonstrates the superiority of electrodes with such a 3D hierarchical architecture. PMID:24643977

  8. Engineering metallic nanostructures for plasmonics and nanophotonics

    PubMed Central

    Lindquist, Nathan C; Nagpal, Prashant; McPeak, Kevin M; Norris, David J; Oh, Sang-Hyun

    2012-01-01

    Metallic nanostructures now play an important role in many applications. In particular, for the emerging fields of plasmonics and nanophotonics, the ability to engineer metals on nanometric scales allows the development of new devices and the study of exciting physics. This review focuses on top-down nanofabrication techniques for engineering metallic nanostructures, along with computational and experimental characterization techniques. A variety of current and emerging applications are also covered. PMID:22790420

  9. 3D ordered nanostructures fabricated by nanosphere lithography using an organometallic etch mask

    NASA Astrophysics Data System (ADS)

    Ling, Xing Yi; Acikgoz, Canet; Phang, In Yee; Hempenius, Mark A.; Reinhoudt, David N.; Vancso, G. Julius; Huskens, Jurriaan

    2010-08-01

    A new approach for fabricating porous structures on silicon substrates and on polymer surfaces, using colloidal particle arrays with a polymer mask of a highly etch-resistant organometallic polymer, is demonstrated. Monolayers of silica particles, with diameters of 60 nm, 150 nm, 300 nm, or 500 nm, were deposited either on a silicon substrate or on a surface coated with polyethersulfone (PES), and the voids of the arrays were filled with poly(ferrocenylmethylphenylsilane) (PFMPS). Argon ion sputtering removed the excess PFMPS on the particles which enabled removal of the particles with HF. Further pattern transfer steps with reactive ion etching for different time intervals provided structures in silicon or in a PES layer. Free-standing PES membranes exhibiting regular arrays of circular holes with high porosity were fabricated by using cellulose acetate as a sacrificial layer. The pores obtained on silicon substrates after etching were used as molds for nanoimprint lithography (NIL). A combination of the techniques of nanosphere lithography (NSL) and NIL has resulted in 3D nanostructures with a hemispherical shape (inherited from the nanoparticles) which was obtained both in silicon and in PMMA.

  10. Emerging Science and Research Opportunities for Metals and Metallic Nanostructures

    NASA Astrophysics Data System (ADS)

    Handwerker, Carol A.; Pollock, Tresa M.

    2014-07-01

    following sections in terms of the following: three-dimensional (3-D) and four-dimensional (4-D) materials science. Structure evolution and the challenge of heterogeneous and multicomponent systems. The science base for property prediction across the length scales. Nanoscale phenomena at surfaces—experiment, theory, and simulation. Prediction and control of the morphology, microstructure, and properties of "bulk" nanostructured metals. Functionality and control of materials far from equilibrium. Hybrid and multifunctional materials assemblies. Materials discovery and design: enhancing the theory-simulation-experiment loop. Following an introduction, these emerging research opportunities are discussed in detail, along with challenges and opportunities for the materials community in the areas of instrumentation, cyberinfrastructure, education, and workforce development.

  11. Leaf-templated synthesis of 3D hierarchical porous cobalt oxide nanostructure as direct electrochemical biosensing interface with enhanced electrocatalysis.

    PubMed

    Han, Lei; Yang, Da-Peng; Liu, Aihua

    2015-01-15

    A novel three-dimensional (3D) hierarchical porous cobalt oxide (Co3O4) architecture was first synthesized through a simple, cost-effective and environmentally friendly leaf-templated strategy. The Co3O4 nanoparticles (30-100 nm) with irregular shapes were interconnected with each other to form a 3D multilayer porous network structure, which provided high specific surface area and numerous electrocatalytic active sites. Subsequently, Co3O4 was successfully utilized as direct electrochemical sensing interface for non-enzymatic detection of H2O2 and glucose. By using chronoamperometry, the current response of the sensor at +0.31 V was linear with H2O2 concentration within 0.4-200 μM with a low limit of detection (LOD) of 0.24 μM (S/N=3) and a high sensitivity of 389.7 μA mM(-1) cm(-2). Two linear ranges of 1-300 μM (with LOD of 0.1 μM and sensitivity of 471.5 μA mM(-1) cm(-2)) and 4-12.5 mM were found at +0.59 V for glucose. In addition, the as-prepared sensor showed excellent stability and anti-interference performance for possible interferents such as ascorbic acid, uric acid, dopamine, acetaminophen and especially 0.15 M chloride ions. Similarly, other various metal oxide nanostructures may be also prepared using this similar strategy for possible applications in catalysis, electrochemical sensors, and fuel cells. PMID:25078713

  12. Laser fabrication of 2D and 3D metal nanoparticle structures and arrays.

    PubMed

    Kuznetsov, A I; Kiyan, R; Chichkov, B N

    2010-09-27

    A novel method for fabrication of 2D and 3D metal nanoparticle structures and arrays is proposed. This technique is based on laser-induced transfer of molten metal nanodroplets from thin metal films. Metal nanoparticles are produced by solidification of these nanodroplets. The size of the transferred nanoparticles can be controllably changed in the range from 180 nm to 1500 nm. Several examples of complex 2D and 3D microstructures generated form gold nanoparticles are demonstrated. PMID:20941016

  13. Chemical Sensors Based on Metal Oxide Nanostructures

    NASA Technical Reports Server (NTRS)

    Hunter, Gary W.; Xu, Jennifer C.; Evans, Laura J.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Mike J.; Liu, Chung-Chiun

    2006-01-01

    This paper is an overview of sensor development based on metal oxide nanostructures. While nanostructures such as nanorods show significan t potential as enabling materials for chemical sensors, a number of s ignificant technical challenges remain. The major issues addressed in this work revolve around the ability to make workable sensors. This paper discusses efforts to address three technical barriers related t o the application of nanostructures into sensor systems: 1) Improving contact of the nanostructured materials with electrodes in a microse nsor structure; 2) Controling nanostructure crystallinity to allow co ntrol of the detection mechanism; and 3) Widening the range of gases that can be detected by using different nanostructured materials. It is concluded that while this work demonstrates useful tools for furt her development, these are just the beginning steps towards realizati on of repeatable, controlled sensor systems using oxide based nanostr uctures.

  14. Self-assembled 3D hierarchical sheaf-like Nb3O7(OH) nanostructures with enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Hu, Pei; Hou, Dongfang; Wen, Yanwei; Shan, Bin; Chen, Chaoji; Huang, Yunhui; Hu, Xianluo

    2015-01-01

    Novel three-dimensional (3D) hierarchical Nb3O7(OH) nanostructures with a sheaf-like nanoarchitecture were fabricated for the first time by a hydrothermal process. Interestingly, the nanosheafs are composed of nanorods with an average diameter of about 25 nm. The as-prepared 3D hierarchical nanostructures possess a high surface area of 77 m2 g-1 with pore diameters of ca. 4.2-12.5 nm. A possible growth mechanism based on the combined Ostwald ripening and self-assembly process was proposed. It is found that both the valence-band top and the conduction-band bottom consist of O 2p and Nb 4d orbitals. Importantly, the 3D hierarchical Nb3O7(OH) nanostructures exhibit enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) under UV-visible light, which is attributed to the unusual hierarchical structure, high surface area, and hybridization of energy bands.Novel three-dimensional (3D) hierarchical Nb3O7(OH) nanostructures with a sheaf-like nanoarchitecture were fabricated for the first time by a hydrothermal process. Interestingly, the nanosheafs are composed of nanorods with an average diameter of about 25 nm. The as-prepared 3D hierarchical nanostructures possess a high surface area of 77 m2 g-1 with pore diameters of ca. 4.2-12.5 nm. A possible growth mechanism based on the combined Ostwald ripening and self-assembly process was proposed. It is found that both the valence-band top and the conduction-band bottom consist of O 2p and Nb 4d orbitals. Importantly, the 3D hierarchical Nb3O7(OH) nanostructures exhibit enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) under UV-visible light, which is attributed to the unusual hierarchical structure, high surface area, and hybridization of energy bands. Electronic supplementary information (ESI) available: XRD patterns, XPS spectra, and SEM images. See DOI: 10.1039/c4nr06580h

  15. Development of metal-assisted chemical etching of silicon as a 3D nanofabrication platform

    NASA Astrophysics Data System (ADS)

    Hildreth, Owen James

    The considerable interest in nanomaterials and nanotechnology over the last decade is attributed to Industry's desire for lower cost, more sophisticated devices and the opportunity that nanotechnology presents for scientists to explore the fundamental properties of nature at near atomic levels. In pursuit of these goals, researchers around the world have worked to both perfect existing technologies and also develop new nano-fabrication methods; however, no technique exists that is capable of producing complex, 2D and 3D nano-sized features of arbitrary shape, with smooth walls, and at low cost. This in part is due to two important limitations of current nanofabrication methods. First, 3D geometry is difficult if not impossible to fabricate, often requiring multiple lithography steps that are both expensive and do not scale well to industrial level fabrication requirements. Second, as feature sizes shrink into the nano-domain, it becomes increasingly difficult to accurately maintain those features over large depths and heights. The ability to produce these structures affordably and with high precision is critically important to a number of existing and emerging technologies such as metamaterials, nano-fluidics, nano-imprint lithography, and more. To overcome these limitations, this study developed a novel and efficient method to etch complex 2D and 3D geometry in silicon with controllable sub-micron to nano-sized features with aspect ratios in excess of 500:1. This study utilized Metal-assisted Chemical Etching (MaCE) of silicon in conjunction with shape-controlled catalysts to fabricate structures such as 3D cycloids, spirals, sloping channels, and out-of-plane rotational structures. This study focused on taking MaCE from a method to fabricate small pores and silicon nanowires using metal catalyst nanoparticles and discontinuous thin films, to a powerful etching technology that utilizes shaped catalysts to fabricate complex, 3D geometry using a single lithography

  16. In Situ Fabrication of 3D Ag@ZnO Nanostructures for Microfluidic Surface-Enhanced Raman Scattering Systems

    PubMed Central

    2015-01-01

    In this work, we develop an in situ method to grow highly controllable, sensitive, three-dimensional (3D) surface-enhanced Raman scattering (SERS) substrates via an optothermal effect within microfluidic devices. Implementing this approach, we fabricate SERS substrates composed of Ag@ZnO structures at prescribed locations inside microfluidic channels, sites within which current fabrication of SERS structures has been arduous. Conveniently, properties of the 3D Ag@ZnO nanostructures such as length, packing density, and coverage can also be adjusted by tuning laser irradiation parameters. After exploring the fabrication of the 3D nanostructures, we demonstrate a SERS enhancement factor of up to ∼2 × 106 and investigate the optical properties of the 3D Ag@ZnO structures through finite-difference time-domain simulations. To illustrate the potential value of our technique, low concentrations of biomolecules in the liquid state are detected. Moreover, an integrated cell-trapping function of the 3D Ag@ZnO structures records the surface chemical fingerprint of a living cell. Overall, our optothermal-effect-based fabrication technique offers an effective combination of microfluidics with SERS, resolving problems associated with the fabrication of SERS substrates in microfluidic channels. With its advantages in functionality, simplicity, and sensitivity, the microfluidic-SERS platform presented should be valuable in many biological, biochemical, and biomedical applications. PMID:25402207

  17. Self-assembled 3D hierarchical sheaf-like Nb3O7(OH) nanostructures with enhanced photocatalytic activity.

    PubMed

    Hu, Pei; Hou, Dongfang; Wen, Yanwei; Shan, Bin; Chen, Chaoji; Huang, Yunhui; Hu, Xianluo

    2015-02-01

    Novel three-dimensional (3D) hierarchical Nb3O7(OH) nanostructures with a sheaf-like nanoarchitecture were fabricated for the first time by a hydrothermal process. Interestingly, the nanosheafs are composed of nanorods with an average diameter of about 25 nm. The as-prepared 3D hierarchical nanostructures possess a high surface area of 77 m(2) g(-1) with pore diameters of ca. 4.2-12.5 nm. A possible growth mechanism based on the combined Ostwald ripening and self-assembly process was proposed. It is found that both the valence-band top and the conduction-band bottom consist of O 2p and Nb 4d orbitals. Importantly, the 3D hierarchical Nb3O7(OH) nanostructures exhibit enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) under UV-visible light, which is attributed to the unusual hierarchical structure, high surface area, and hybridization of energy bands. PMID:25536277

  18. Strain in a silicon-on-insulator nanostructure revealed by 3D x-ray Bragg ptychography

    PubMed Central

    Chamard, V.; Allain, M.; Godard, P.; Talneau, A.; Patriarche, G.; Burghammer, M.

    2015-01-01

    Progresses in the design of well-defined electronic band structure and dedicated functionalities rely on the high control of complex architectural device nano-scaled structures. This includes the challenging accurate description of strain fields in crystalline structures, which requires non invasive and three-dimensional (3D) imaging methods. Here, we demonstrate in details how x-ray Bragg ptychography can be used to quantify in 3D a displacement field in a lithographically patterned silicon-on-insulator structure. The image of the crystalline properties, which results from the phase retrieval of a coherent intensity data set, is obtained from a well-controlled optimized process, for which all steps are detailed. These results confirm the promising perspectives of 3D Bragg ptychography for the investigation of complex nano-structured crystals in material science. PMID:25984829

  19. Strain in a silicon-on-insulator nanostructure revealed by 3D x-ray Bragg ptychography.

    PubMed

    Chamard, V; Allain, M; Godard, P; Talneau, A; Patriarche, G; Burghammer, M

    2015-01-01

    Progresses in the design of well-defined electronic band structure and dedicated functionalities rely on the high control of complex architectural device nano-scaled structures. This includes the challenging accurate description of strain fields in crystalline structures, which requires non invasive and three-dimensional (3D) imaging methods. Here, we demonstrate in details how x-ray Bragg ptychography can be used to quantify in 3D a displacement field in a lithographically patterned silicon-on-insulator structure. The image of the crystalline properties, which results from the phase retrieval of a coherent intensity data set, is obtained from a well-controlled optimized process, for which all steps are detailed. These results confirm the promising perspectives of 3D Bragg ptychography for the investigation of complex nano-structured crystals in material science. PMID:25984829

  20. Significant enhancement of power conversion efficiency for dye sensitized solar cell using 1D/3D network nanostructures as photoanodes

    PubMed Central

    Wang, Hao; Wang, Baoyuan; Yu, Jichao; Hu, Yunxia; Xia, Chen; Zhang, Jun; Liu, Rong

    2015-01-01

    The single–crystalline TiO2 nanorod arrays with rutile phase have attracted much attention in the dye sensitized solar cells (DSSCs) applications because of their superior chemical stability, better electron transport properties, higher refractive index and low production cost. However, it suffers from a low surface area as compared with TiO2 nanoparticle films. In order to enlarge the surface area of TiO2 nanorod arrays, the 1D nanorods/3D nanotubes sample was synthesized using a facile two-step hydrothermal process involving hydrothermal growth 1D/3D nanorods and followed by post-etching treatment. In such bi-layer structure, the oriented TiO2 nanorods layer could provide direct pathway for fast electron transportation, and the 3D nanotubes layer offers a higher surface area for dye loading, therefore, the 1D nanorods/3D nanotubes photoanode exhibited faster electron transport and higher surface area than either 1D or 3D nanostructures alone, and an highest efficiency of 7.68% was achieved for the DSSCs based on 1D nanorods/3D nanotubes photoanode with further TiCl4 treatment. PMID:25800933

  1. Significant enhancement of power conversion efficiency for dye sensitized solar cell using 1D/3D network nanostructures as photoanodes

    NASA Astrophysics Data System (ADS)

    Wang, Hao; Wang, Baoyuan; Yu, Jichao; Hu, Yunxia; Xia, Chen; Zhang, Jun; Liu, Rong

    2015-03-01

    The single-crystalline TiO2 nanorod arrays with rutile phase have attracted much attention in the dye sensitized solar cells (DSSCs) applications because of their superior chemical stability, better electron transport properties, higher refractive index and low production cost. However, it suffers from a low surface area as compared with TiO2 nanoparticle films. In order to enlarge the surface area of TiO2 nanorod arrays, the 1D nanorods/3D nanotubes sample was synthesized using a facile two-step hydrothermal process involving hydrothermal growth 1D/3D nanorods and followed by post-etching treatment. In such bi-layer structure, the oriented TiO2 nanorods layer could provide direct pathway for fast electron transportation, and the 3D nanotubes layer offers a higher surface area for dye loading, therefore, the 1D nanorods/3D nanotubes photoanode exhibited faster electron transport and higher surface area than either 1D or 3D nanostructures alone, and an highest efficiency of 7.68% was achieved for the DSSCs based on 1D nanorods/3D nanotubes photoanode with further TiCl4 treatment.

  2. Significant enhancement of power conversion efficiency for dye sensitized solar cell using 1D/3D network nanostructures as photoanodes.

    PubMed

    Wang, Hao; Wang, Baoyuan; Yu, Jichao; Hu, Yunxia; Xia, Chen; Zhang, Jun; Liu, Rong

    2015-01-01

    The single-crystalline TiO2 nanorod arrays with rutile phase have attracted much attention in the dye sensitized solar cells (DSSCs) applications because of their superior chemical stability, better electron transport properties, higher refractive index and low production cost. However, it suffers from a low surface area as compared with TiO2 nanoparticle films. In order to enlarge the surface area of TiO2 nanorod arrays, the 1D nanorods/3D nanotubes sample was synthesized using a facile two-step hydrothermal process involving hydrothermal growth 1D/3D nanorods and followed by post-etching treatment. In such bi-layer structure, the oriented TiO2 nanorods layer could provide direct pathway for fast electron transportation, and the 3D nanotubes layer offers a higher surface area for dye loading, therefore, the 1D nanorods/3D nanotubes photoanode exhibited faster electron transport and higher surface area than either 1D or 3D nanostructures alone, and an highest efficiency of 7.68% was achieved for the DSSCs based on 1D nanorods/3D nanotubes photoanode with further TiCl4 treatment. PMID:25800933

  3. Nano-Structural Elucidation in Carbon Black Loaded NR Vulcanizate by 3D-TEM and In Situ WAXD Measurements

    SciTech Connect

    Ikeda,Y.; Kato, A.; Shimanuki, J.; Kohjiya, S.; Tosaka, M.; Poompradub, S.; Toki, S.; Hsiao, B.

    2007-01-01

    Three dimensional (3D) visualization of nanometer structure of carbon black dispersion in rubbery matrix has successfully been studied and reported in this paper. Use of 3D-TEM, which is computerized tomography combined with transmission electron microscopy (TEM), enabled us to reconstruct 3D images of carbon black aggregates in natural rubber (NR) matrix. The TEM measurements were conducted by a bright-field method on thin samples without any electron staining. The sample was subject to uni-axial tilting (+65 degree to -65 degree with 2 degree increment) in the sample chamber, and 66 TEM images were taken on each sample. These TEM images were used for computerized tomography to reconstruct the 3D image. This technique is designated as 3D-TEM. The nano-structural features observed by 3D-TEM were in conformity with the electron-conductivity results, and the percolation behavior was recognized. These results were further supplemented by in situ wide-angle X-ray diffraction (WAXD), i.e., simultaneous WAXD and tensile measurements on the sample to observe the strain-induced crystallization in NR vulcanizate. Upon tensile elongation, the crystallization was clearly observed in WAXD in the presence of carbon black, and it contributed to the tensile properties. In order to understand the performances of filled NR vulcanizates, it surely is necessary to know the structural states of the mixed nano-filler and the crystallites produced upon elongation.

  4. From 2D to 3D: novel nanostructured scaffolds to investigate signalling in reconstructed neuronal networks.

    PubMed

    Bosi, Susanna; Rauti, Rossana; Laishram, Jummi; Turco, Antonio; Lonardoni, Davide; Nieus, Thierry; Prato, Maurizio; Scaini, Denis; Ballerini, Laura

    2015-01-01

    To recreate in vitro 3D neuronal circuits will ultimately increase the relevance of results from cultured to whole-brain networks and will promote enabling technologies for neuro-engineering applications. Here we fabricate novel elastomeric scaffolds able to instruct 3D growth of living primary neurons. Such systems allow investigating the emerging activity, in terms of calcium signals, of small clusters of neurons as a function of the interplay between the 2D or 3D architectures and network dynamics. We report the ability of 3D geometry to improve functional organization and synchronization in small neuronal assemblies. We propose a mathematical modelling of network dynamics that supports such a result. Entrapping carbon nanotubes in the scaffolds remarkably boosted synaptic activity, thus allowing for the first time to exploit nanomaterial/cell interfacing in 3D growth support. Our 3D system represents a simple and reliable construct, able to improve the complexity of current tissue culture models. PMID:25910072

  5. Silica-metal core-shell nanostructures.

    PubMed

    Jankiewicz, B J; Jamiola, D; Choma, J; Jaroniec, M

    2012-01-15

    Silica-metal nanostructures consisting of silica cores and metal nanoshells attract a lot of attention because of their unique properties and potential applications ranging from catalysis and biosensing to optical devices and medicine. The important feature of these nanostructures is the possibility of controlling their properties by the variation of their geometry, shell morphology and shell material. This review is devoted to silica-noble metal core-shell nanostructures; specifically, it outlines the main methods used for the preparation and surface modification of silica particles and presents the major strategies for the formation of metal nanoshells on the modified silica particles. A special emphasis is given to the Stöber method, which is relatively simple, effective and well verified for the synthesis of large and highly uniform silica particles (with diameters from 100 nm to a few microns). Next, the surface chemistry of these particles is discussed with a special focus on the attachment of specific organic groups such as aminopropyl or mercaptopropyl groups, which interact strongly with metal species. Finally, the synthesis, characterization and application of various silica-metal core-shell nanostructures are reviewed, especially in relation to the siliceous cores with gold or silver nanoshells. Nowadays, gold is most often used metal for the formation of nanoshells due to its beneficial properties for many applications. However, other metals such as silver, platinum, palladium, nickel and copper were also used for fabrication of core-shell nanostructures. Silica-metal nanostructures can be prepared using various methods, for instance, (i) growth of metal nanoshells on the siliceous cores with deposited metal nanoparticles, (ii) reduction of metal species accompanied by precipitation of metal nanoparticles on the modified silica cores, and (iii) formation of metal nanoshells under ultrasonic conditions. A special emphasis is given to the seed

  6. Template-free solvothermal synthesis of 3D hierarchical nanostructured boehmite assembled by nanosheets

    NASA Astrophysics Data System (ADS)

    Li, Guangci; Guan, Lili; Liu, Yunqi; Liu, Chenguang

    2012-09-01

    In the absence of template and surfactant, hierarchical nanostructured boehmite was synthesized via a simple solvothermal route using aluminum nitrate as aluminum source and isopropanol-toluene mixture as solvent. The crystal structures, morphologies and textural properties of products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N2 adsorption-desorption technique. The as-obtained hierarchical nanostructures consist of nanosheets keeping Brunauer-Emmett-Teller (BET) specific surface area and pore volume of ca. 264.7 m2/g and 1.2 cm3/g, respectively. The experimental results show that the longer reaction time and the lower reaction temperature are unfavorable to the formation of hierarchical nanostructures. Moreover, the properties of solvent have important influence on the morphology of product. The possible formation mechanism of boehmite hierarchical nanostructures was proposed and discussed.

  7. Nanostructured metal foams: synthesis and applications

    SciTech Connect

    Luther, Erik P; Tappan, Bryce; Mueller, Alex; Mihaila, Bogdan; Volz, Heather; Cardenas, Andreas; Papin, Pallas; Veauthier, Jackie; Stan, Marius

    2009-01-01

    Fabrication of monolithic metallic nanoporous materials is difficult using conventional methodology. Here they report a relatively simple method of synthesizing monolithic, ultralow density, nanostructured metal foams utilizing self-propagating combustion synthesis of novel metal complexes containing high nitrogen energetic ligands. Nanostructured metal foams are formed in a post flame-front dynamic assembly with densities as low as 0.011 g/cc and surface areas as high as 270 m{sup 2}/g. They have produced metal foams via this method of titanium, iron, cobalt, nickel, zirconium, copper, palladium, silver, hafnium, platinum and gold. Microstructural features vary as a function of composition and process parameters. Applications for the metal foams are discussed including hydrogen absorption in palladium foams. A model for the sorption kinetics of hydrogen in the foams is presented.

  8. Commercial Implementation of Model-Based Manufacturing of Nanostructured Metals

    SciTech Connect

    Lowe, Terry C.

    2012-07-24

    Computational modeling is an essential tool for commercial production of nanostructured metals. Strength is limited by imperfections at the high strength levels that are achievable in nanostructured metals. Processing to achieve homogeneity at the micro- and nano-scales is critical. Manufacturing of nanostructured metals is intrinsically a multi-scale problem. Manufacturing of nanostructured metal products requires computer control, monitoring and modeling. Large scale manufacturing of bulk nanostructured metals by Severe Plastic Deformation is a multi-scale problem. Computational modeling at all scales is essential. Multiple scales of modeling must be integrated to predict and control nanostructural, microstructural, macrostructural product characteristics and production processes.

  9. Magnetic Behavior of 3d Transition Metals in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Miao, Maosheng; Lambrecht, Walter R. L.

    2002-03-01

    The magnetic properties of cubic silicon carbide (SiC) doped by first row transition metals (TM) are studied within the local spin density functional approach using the linearized muffin-tin orbital method in the atomic sphere approximation. It is found that the couplings between the TM d orbitals and the dangling bond states are stronger for the Si site doping, which gives a larger e-t2 splitting. The stronger coupling also delocalizes the t2 states and hence reduces the spin polarization. As a result the TMs tend to have a low spin configuration at the Si site and a high spin one at the C site. On the other hand, the strong couplings lower the formation energy at the Si site and TMs prefer to dope the Si site in both the Si-rich and C-rich limits. For Si site doping, Cr and Mn exhibit the most pronounced magnetic behavior with Cr favoring ferromagnetic and Mn antiferromagnetic nearest neighbor coupling.

  10. Fused filament 3D printing of ionic polymer-metal composites (IPMCs)

    NASA Astrophysics Data System (ADS)

    Carrico, James D.; Traeden, Nicklaus W.; Aureli, Matteo; Leang, Kam K.

    2015-12-01

    This paper describes a new three-dimensional (3D) fused filament additive manufacturing (AM) technique in which electroactive polymer filament material is used to build soft active 3D structures, layer by layer. Specifically, the unique actuation and sensing properties of ionic polymer-metal composites (IPMCs) are exploited in 3D printing to create electroactive polymer structures for application in soft robotics and bio-inspired systems. The process begins with extruding a precursor material (non-acid Nafion precursor resin) into a thermoplastic filament for 3D printing. The filament is then used by a custom-designed 3D printer to manufacture the desired soft polymer structures, layer by layer. Since at this stage the 3D-printed samples are not yet electroactive, a chemical functionalization process follows, consisting in hydrolyzing the precursor samples in an aqueous solution of potassium hydroxide and dimethyl sulfoxide. Upon functionalization, metal electrodes are applied on the samples through an electroless plating process, which enables the 3D-printed IPMC structures to be controlled by voltage signals for actuation (or to act as sensors). This innovative AM process is described in detail and the performance of 3D printed IPMC actuators is compared to an IPMC actuator fabricated from commercially available Nafion sheet material. The experimental results show comparable performance between the two types of actuators, demonstrating the potential and feasibility of creating functional 3D-printed IPMCs.

  11. Fabrication of 3D metal/polymer microstructures by site-selective metal coating

    NASA Astrophysics Data System (ADS)

    Takeyasu, N.; Tanaka, T.; Kawata, S.

    2008-02-01

    Three-dimensional silver/polymer conjugated microstructures were fabricated by site-selective metal deposition on photopolymer structures in the sub-micrometer scale. Photopolymerizable resins with and without an amide group were independently prepared, and a three-dimensional polymer structure was fabricated with those resins by means of the two-photon-induced photopolymerization technique to confine the photopolymerization to a sub-micrometer volume. Silver was selectively deposited on the surface of the amide-containing polymer parts by electroless plating. This method can provide 3D arbitrary silver/polymer composite microstructures with sub-micrometer resolution.

  12. Analysis of 3D-printed metal for rapid-prototyped reflective terahertz optics.

    PubMed

    Headland, Daniel; Withayachumnankul, Withawat; Webb, Michael; Ebendorff-Heidepriem, Heike; Luiten, Andre; Abbott, Derek

    2016-07-25

    We explore the potential of 3D metal printing to realize complex conductive terahertz devices. Factors impacting performance such as printing resolution, surface roughness, oxidation, and material loss are investigated via analytical, numerical, and experimental approaches. The high degree of control offered by a 3D-printed topology is exploited to realize a zone plate operating at 530 GHz. Reflection efficiency at this frequency is found to be over 90%. The high-performance of this preliminary device suggest that 3D metal printing can play a strong role in guided-wave and general beam control devices in the terahertz range. PMID:27464185

  13. Analysis of 3D-printed metal for rapid-prototyped reflective terahertz optics

    NASA Astrophysics Data System (ADS)

    Headland, Daniel; Withayachumnankul, Withawat; Webb, Michael; Ebendorff-Heidepriem, Heike; Luiten, Andre; Abbott, Derek

    2016-07-01

    We explore the potential of 3D metal printing to realize complex conductive terahertz devices. Factors impacting performance such as printing resolution, surface roughness, oxidation, and material loss are investigated via analytical, numerical, and experimental approaches. The high degree of control offered by a 3D-printed topology is exploited to realize a zone plate operating at 530 GHz. Reflection efficiency at this frequency is found to be over 90%. The high-performance of this preliminary device suggest that 3D metal printing can play a strong role in guided-wave and general beam control devices in the terahertz range.

  14. Prediction of spin-dependent electronic structure in 3d-transition-metal doped antimonene

    NASA Astrophysics Data System (ADS)

    Yang, L. F.; Song, Y.; Mi, W. B.; Wang, X. C.

    2016-07-01

    We investigate the geometric structure and electronic and magnetic properties of 3d-transition-metal atom doped antimonene using spin-polarized first-principles calculations. Strong orbital hybridization exhibits between 3d-transition-metal and Sb atoms, where covalent bonds form in antimonene. A spin-polarized semiconducting state appears in Cr-doped antimonene, while half-metallic states appear by doping Ti, V, and Mn. These findings indicate that once combined with doping states, the bands of antimonene systems offer a variety of features. Specific dopants lead to half-metallic characters with high spin polarization that has potential application in spintronics.

  15. Printing of metallic 3D micro-objects by laser induced forward transfer.

    PubMed

    Zenou, Michael; Kotler, Zvi

    2016-01-25

    Digital printing of 3D metal micro-structures by laser induced forward transfer under ambient conditions is reviewed. Recent progress has allowed drop on demand transfer of molten, femto-liter, metal droplets with a high jetting directionality. Such small volume droplets solidify instantly, on a nanosecond time scale, as they touch the substrate. This fast solidification limits their lateral spreading and allows the fabrication of high aspect ratio and complex 3D metal structures. Several examples of micron-scale resolution metal objects printed using this method are presented and discussed. PMID:26832524

  16. Initiator-integrated 3D printing enables the formation of complex metallic architectures.

    PubMed

    Wang, Xiaolong; Guo, Qiuquan; Cai, Xiaobing; Zhou, Shaolin; Kobe, Brad; Yang, Jun

    2014-02-26

    Three-dimensional printing was used to fabricate various metallic structures by directly integrating a Br-containing vinyl-terminated initiator into the 3D resin followed by surface-initiated atomic-transfer radical polymerization (ATRP) and subsequent electroless plating. Cu- and Ni-coated complex structures, such as microlattices, hollow balls, and even Eiffel towers, were prepared. Moreover, the method is also capable of fabricating ultralight cellular metals with desired structures by simply etching the polymer template away. By combining the merits of 3D printing in structure design with those of ATRP in surface modification and polymer-assisted ELP of metals, this universal, robust, and cost-effective approach has largely extended the capability of 3D printing and will make 3D printing technology more practical in areas of electronics, acoustic absorption, thermal insulation, catalyst supports, and others. PMID:24328276

  17. Facilely synthesis of 3D CuxO-Cu nanostructures as binder-free electrode for supercapacitors

    NASA Astrophysics Data System (ADS)

    Niu, Lengyuan; Wang, Yidan; Shan, Shen; Ruan, Fengping; Xu, Man; Sun, Zhenkun; Li, Can; Liu, Xinjuan; Gong, Yinyan

    2016-05-01

    3D CuxO-Cu nanostructures were synthesized through a simple chemical corrosion method and were employed as binder-free electrodes for supercapacitors. Owing to the direct growth of the active materials onto the Cu foam without any binders, and the 3D interconnected structure ensures a highly conductive network favorable for electron transfer, the as-prepared electrode exhibit a high specific capacitance of 111 mF cm-2 at 0.5 mA cm-2 and a better rate capability of 80 mF cm-2 at 10 mA cm-2. Besides, the CuxO-Cu//AC asymmetric supercapacitor can deliver a high energy density of 34.36 μW h cm-2, thus showing great potential for supercapacitor applications.

  18. Fabrication and characterization of metal-to-metal interconnect structures for 3-D integration

    NASA Astrophysics Data System (ADS)

    Huffman, Alan; Lannon, John; Lueck, Matthew; Gregory, Christopher; Temple, Dorota

    2009-03-01

    The use of collapsible (solder) bump interconnects in pixel detector hybridization has been shown to be very successful. However, as pixel sizes decrease, the use of non-collapsible metal-to-metal bump bonding methods is needed to push the interconnect dimensions smaller. Furthermore, these interconnects are compatible with 3D intgration technologies which are being considered to increase overall pixel and system performance. These metal-to-metal bonding structures provide robust mechanical and electrical connections and allow for a dramatic increase in pixel density. Of particular interest are Cu-Cu thermocompression bonding and Cu/Sn-Cu solid-liquid diffusion bonding processes. Working with Fermilab, RTI undertook a demonstration to show that these bump structures could be reliably used to interconnect devices designed with 20 micron I/O pitch. Cu and Cu/Sn bump fabrication processes were developed to provide a well-controlled surface topography necessary for the formation of low resistance, high yielding, and reliable interconnects. The electrical resistance and yield has been quantified based on electrical measurements of daisy chain test structures and the mechanical strength of the bonding has been quantified through die shear testing. The reliability has been characterized through studies of the impact of thermal exposure on the mechanical performance of the bonds. Cross-section SEM analysis, coupled with high resolution energy dispersive spectroscopy, has provided insight into the physical and chemical nature of the bonding interfaces and aided in the evaluation of the long-term stability of the bonds.

  19. Selective synthesis of rhodium-based nanoframe catalysts by chemical etching of 3d metals.

    PubMed

    Zhang, Zhi-Ping; Zhu, Wei; Yan, Chun-Hua; Zhang, Ya-Wen

    2015-03-01

    We demonstrate a general strategy for the highly selective synthesis of Rh-based multi-metallic nanoframes through preferential etching of 3d metals, including Cu and Ni. Compared with Rh-Cu nanooctahedrons/C, Rh-Cu nanooctahedral frames/C show greatly enhanced activity toward hydrazine decomposition at room temperature. PMID:25665751

  20. Laser-assisted direct ink writing of planar and 3D metal architectures

    PubMed Central

    Skylar-Scott, Mark A.; Gunasekaran, Suman; Lewis, Jennifer A.

    2016-01-01

    The ability to pattern planar and freestanding 3D metallic architectures at the microscale would enable myriad applications, including flexible electronics, displays, sensors, and electrically small antennas. A 3D printing method is introduced that combines direct ink writing with a focused laser that locally anneals printed metallic features “on-the-fly.” To optimize the nozzle-to-laser separation distance, the heat transfer along the printed silver wire is modeled as a function of printing speed, laser intensity, and pulse duration. Laser-assisted direct ink writing is used to pattern highly conductive, ductile metallic interconnects, springs, and freestanding spiral architectures on flexible and rigid substrates. PMID:27185932

  1. Laser-assisted direct ink writing of planar and 3D metal architectures.

    PubMed

    Skylar-Scott, Mark A; Gunasekaran, Suman; Lewis, Jennifer A

    2016-05-31

    The ability to pattern planar and freestanding 3D metallic architectures at the microscale would enable myriad applications, including flexible electronics, displays, sensors, and electrically small antennas. A 3D printing method is introduced that combines direct ink writing with a focused laser that locally anneals printed metallic features "on-the-fly." To optimize the nozzle-to-laser separation distance, the heat transfer along the printed silver wire is modeled as a function of printing speed, laser intensity, and pulse duration. Laser-assisted direct ink writing is used to pattern highly conductive, ductile metallic interconnects, springs, and freestanding spiral architectures on flexible and rigid substrates. PMID:27185932

  2. Laser-assisted direct ink writing of planar and 3D metal architectures

    NASA Astrophysics Data System (ADS)

    Skylar-Scott, Mark A.; Gunasekaran, Suman; Lewis, Jennifer A.

    2016-05-01

    The ability to pattern planar and freestanding 3D metallic architectures at the microscale would enable myriad applications, including flexible electronics, displays, sensors, and electrically small antennas. A 3D printing method is introduced that combines direct ink writing with a focused laser that locally anneals printed metallic features “on-the-fly.” To optimize the nozzle-to-laser separation distance, the heat transfer along the printed silver wire is modeled as a function of printing speed, laser intensity, and pulse duration. Laser-assisted direct ink writing is used to pattern highly conductive, ductile metallic interconnects, springs, and freestanding spiral architectures on flexible and rigid substrates.

  3. Synthesis on structure and properties of zinc nanocrystal in high ordered 3D nanostructures

    SciTech Connect

    Sathyaseelan, B.; Manigandan, A.; Anbarasu, V.; Sivakumar, K.

    2015-06-24

    The wet impregnation method was employed to prepare ZnO encapsulated in mesoporous silica (ZnO/KIT-6). The prepared ZnO/KIT-6 samples have been studied by X-ray diffraction, transmission electron microscope, and nitrogen adsorption–desorption isotherm. The low angle powder XRD patterns of Calcined ZnO/KIT-6 materials showed a phase that can be indexed to cubic Ia3d. Tem images revealed well ordered cubic 3D nanoporous chennels. The ZnO encapsulated in KIT-6 can be used as light-emitting diodes and ultraviolet nanolasers.

  4. 3-D printing of liquid metals for stretchable and flexible conductors

    NASA Astrophysics Data System (ADS)

    Trlica, Chris; Parekh, Dishit Paresh; Panich, Lazar; Ladd, Collin; Dickey, Michael D.

    2014-06-01

    3-D printing is an emerging technology that has been used primarily on small scales for rapid prototyping, but which could also herald a wider movement towards decentralized, highly customizable manufacturing. Polymers are the most common materials to be 3-D printed today, but there is great demand for a way to easily print metals. Existing techniques for 3-D printing metals tend to be expensive and energy-intensive, and usually require high temperatures or pressures, making them incompatible with polymers, organics, soft materials, and biological materials. Here, we describe room temperature liquid metals as complements to polymers for 3-D printing applications. These metals enable the fabrication of soft, flexible, and stretchable devices. We survey potential room temperature liquid metal candidates and describe the benefits of gallium and its alloys for these purposes. We demonstrate the direct printing of a liquid gallium alloy in both 2-D and 3-D and highlight the structures and shapes that can be fabricated using these processes.

  5. Facile 3D Metal Electrode Fabrication for Energy Applications via Inkjet Printing and Shape Memory Polymer

    NASA Astrophysics Data System (ADS)

    Roberts, R. C.; Wu, J.; Hau, N. Y.; Chang, Y. H.; Feng, S. P.; Li, D. C.

    2014-11-01

    This paper reports on a simple 3D metal electrode fabrication technique via inkjet printing onto a thermally contracting shape memory polymer (SMP) substrate. Inkjet printing allows for the direct patterning of structures from metal nanoparticle bearing liquid inks. After deposition, these inks require thermal curing steps to render a stable conductive film. By printing onto a SMP substrate, the metal nanoparticle ink can be cured and substrate shrunk simultaneously to create 3D metal microstructures, forming a large surface area topology well suited for energy applications. Polystyrene SMP shrinkage was characterized in a laboratory oven from 150-240°C, resulting in a size reduction of 1.97-2.58. Silver nanoparticle ink was patterned into electrodes, shrunk, and the topology characterized using scanning electron microscopy. Zinc-Silver Oxide microbatteries were fabricated to demonstrate the 3D electrodes compared to planar references. Characterization was performed using 10M potassium hydroxide electrolyte solution doped with zinc oxide (57g/L). After a 300s oxidation at 3Vdc, the 3D electrode battery demonstrated a 125% increased capacity over the reference cell. Reference cells degraded with longer oxidations, but the 3D electrodes were fully oxidized for 4 hours, and exhibited a capacity of 5.5mA-hr/cm2 with stable metal performance.

  6. Controlling optical response of metallic nanostructure

    SciTech Connect

    Grigorenko, Ilya

    2008-01-01

    In this talk I am going to discuss the direct and inverse problems in nanoplasmonics in classical, and in particular quantum regimes of excitations. The inverse problem in nanoplasmonics is aimed to control the eigenspectrum, excitations,and other physical properties of nanosized quantum systems via controlling their size, shape, and structural composition. Using a combination of modern modeling techniques and optimization procedures, one can succeed to solve the inverse problem, namely, to find a nanostructure which has the desired functionality, or to find optimal control field in the presence of known nanostructured metallic surface.

  7. Pillared Graphene: A New 3-D Innovative Network Nanostructure Augments Hydrogen Storage

    NASA Astrophysics Data System (ADS)

    Georgios, Dimitrakakis K.; Emmanuel, Tylianakis; George, Froudakis E.

    2009-08-01

    Nowadays, people have turned into finding an alternative power source for everyday applications. One of the most promising energy fuels is hydrogen. It can be used as an energy carrier at small portable devices (e.g. laptops and/or cell phones) up to larger, like cars. Hydrogen is considered as the perfect fuel. It can be burnt in combustion engines and the only by-product is water. For hydrogen-powered vehicles a big liming factor is the gas tank and is the reason for not using widely hydrogen in automobile applications. According to United States' Department of Energy (D.O.E.) the target for reversible hydrogen storage in mobile applications is 6% wt. and 45 gr. H2/L and these should be met by 2010. After their synthesis Carbon Nanotubes (CNTs) were considered as ideal candidates for hydrogen storage especially after some initially incorrect but invitingly results. As it was proven later, pristine carbon nanotubes cannot achieve D.O.E.'s targets in ambient conditions of pressure and temperature. Therefore, a way to increase their hydrogen storage capacity should be found. An attempt was done by doping CNTs with alkali metal atoms. Although the results were promising, even that increment was not enough. Consequently, new architectures were suggested as materials that could potentially enhance hydrogen storage. In this work a novel three dimensional (3-D) nanoporous carbon structure called Pillared Graphene (Figure 1) is proposed for augmented hydrogen storage in ambient conditions. Pillared Graphene consists of parallel graphene sheets and CNTs that act like pillars and support the graphene sheets. The entire structure (Figure 1) can be resembled like a building in its early stages of construction, where the floors are represented by graphene sheets and the pillars are the CNTs. As shown in Figure 1, CNTs do not penetrate the structure from top to bottom. Instead, they alternately go up and down, so that on the same plane do not exist two neighboring CNTs with the

  8. Metal plasmas for the fabrication of nanostructures

    SciTech Connect

    Anders, Andre

    2006-09-21

    A review is provided covering metal plasma production, theenergetic condensation of metal plasmas, and the formation ofnanostructures using such plasmas. Plasma production techniques includepulsed laser ablation, filtered cathodic arcs, and various forms ofionized physical vapor deposition, namely magnetron sputtering withionization of sputtered atoms in radio frequency discharges,self-sputtering, and high power impulse magnetron sputtering. Thediscussion of energetic condensation focuses on the control of kineticenergy by biasing and also includes considerations of the potentialenergy and the processes occurring at subplantation and implantation. Inthe final section on nanostructures, two different approaches arediscussed. In the top-down approach, the primary nanostructures arelithographically produced and metal plasma is used to coat or filltrenches and vias. Additionally, multilayers with nanosize periods(nanolaminates) can be produced. In the bottom-up approach, thermodynamicforces are used to fabricate nanocomposites and nanoporous materials bydecomposition and dealloying.

  9. Nanostructured metal-polyaniline composites

    DOEpatents

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2010-08-31

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  10. Nanostructured metal sulfides for energy storage.

    PubMed

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-09-01

    Advanced electrodes with a high energy density at high power are urgently needed for high-performance energy storage devices, including lithium-ion batteries (LIBs) and supercapacitors (SCs), to fulfil the requirements of future electrochemical power sources for applications such as in hybrid electric/plug-in-hybrid (HEV/PHEV) vehicles. Metal sulfides with unique physical and chemical properties, as well as high specific capacity/capacitance, which are typically multiple times higher than that of the carbon/graphite-based materials, are currently studied as promising electrode materials. However, the implementation of these sulfide electrodes in practical applications is hindered by their inferior rate performance and cycling stability. Nanostructures offering the advantages of high surface-to-volume ratios, favourable transport properties, and high freedom for the volume change upon ion insertion/extraction and other reactions, present an opportunity to build next-generation LIBs and SCs. Thus, the development of novel concepts in material research to achieve new nanostructures paves the way for improved electrochemical performance. Herein, we summarize recent advances in nanostructured metal sulfides, such as iron sulfides, copper sulfides, cobalt sulfides, nickel sulfides, manganese sulfides, molybdenum sulfides, tin sulfides, with zero-, one-, two-, and three-dimensional morphologies for LIB and SC applications. In addition, the recently emerged concept of incorporating conductive matrices, especially graphene, with metal sulfide nanomaterials will also be highlighted. Finally, some remarks are made on the challenges and perspectives for the future development of metal sulfide-based LIB and SC devices. PMID:25073046

  11. Coherently Embedded Ag Nanostructures in Si: 3D Imaging and their application to SERS

    PubMed Central

    Juluri, R. R.; Rath, A.; Ghosh, A.; Bhukta, A.; Sathyavathi, R.; Rao, D. Narayana; Müller, Knut; Schowalter, Marco; Frank, Kristian; Grieb, Tim; Krause, Florian; Rosenauer, A.; Satyam, P. V.

    2014-01-01

    Surface enhanced Raman spectroscopy (SERS) has been established as a powerful tool to detect very low-concentration bio-molecules. One of the challenging problems is to have reliable and robust SERS substrate. Here, we report on a simple method to grow coherently embedded (endotaxial) silver nanostructures in silicon substrates, analyze their three-dimensional shape by scanning transmission electron microscopy tomography and demonstrate their use as a highly reproducible and stable substrate for SERS measurements. Bi-layers consisting of Ag and GeOx thin films were grown on native oxide covered silicon substrate using a physical vapor deposition method. Followed by annealing at 800°C under ambient conditions, this resulted in the formation of endotaxial Ag nanostructures of specific shape depending upon the substrate orientation. These structures are utilized for detection of Crystal Violet molecules of 5 × 10−10 M concentrations. These are expected to be one of the highly robust, reusable and novel substrates for single molecule detection. PMID:24717601

  12. Two step formation of metal aggregates by surface X-ray radiolysis under Langmuir monolayers: 2D followed by 3D growth.

    PubMed

    Mukherjee, Smita; Fauré, Marie-Claude; Goldmann, Michel; Fontaine, Philippe

    2015-01-01

    In order to form a nanostructured metallic layer below a Langmuir monolayer, radiolysis synthesis was carried out in an adapted geometry that we call surface X-ray radiolysis. In this procedure, an X-ray beam produced by a synchrotron beamline intercepts the surface of an aqueous metal-ion solution covered by a Langmuir monolayer at an angle of incidence below the critical angle for total internal reflection. Underneath the organic layer, the X-ray beam induces the radiolytic synthesis of a nanostructured metal-organic layer whose ultrathin thickness is defined by the vertical X-ray penetration depth. We have shown that increasing the X-ray flux on the surface, which considerably enhances the kinetics of the silver layer formation, results in a second growth regime of silver nanocrystals. Here the formation of the oriented thin layer is followed by the appearance of a 3D powder of silver clusters. PMID:26734531

  13. Construction of 3D nanostructure hierarchical porous graphitic carbons by charge-induced self-assembly and nanocrystal-assisted catalytic graphitization for supercapacitors.

    PubMed

    Ma, Fangwei; Ma, Di; Wu, Guang; Geng, Weidan; Shao, Jinqiu; Song, Shijiao; Wan, Jiafeng; Qiu, Jieshan

    2016-05-10

    A smart and sustainable strategy based on charge-induced self-assembly and nanocrystal-assisted catalytic graphitization is explored for the efficient construction of 3D nanostructure hierarchical porous graphitic carbons from the pectin biopolymer. The electrostatic interaction between the negatively charged pectin chains and magnesium ions plays a crucial role in the formation of 3D architectures. The 3D HPGCs possess a three-dimensional carbon framework with a hierarchical porous structure, flake-like graphitic carbon walls and high surface area (1320 m(2) g(-1)). The 3D HPGCs show an outstanding specific capacitance of 274 F g(-1) and excellent rate capability with a high capacitance retention of 85% at a high current density of 50 A g(-1) for supercapacitor electrodes. This strategy provided a novel approach to effectively construct 3D porous carbon nanostructures from biopolymers. PMID:27115341

  14. Laser jetting of femto-liter metal droplets for high resolution 3D printed structures.

    PubMed

    Zenou, M; Sa'ar, A; Kotler, Z

    2015-01-01

    Laser induced forward transfer (LIFT) is employed in a special, high accuracy jetting regime, by adequately matching the sub-nanosecond pulse duration to the metal donor layer thickness. Under such conditions, an effective solid nozzle is formed, providing stability and directionality to the femto-liter droplets which are printed from a large gap in excess of 400 μm. We illustrate the wide applicability of this method by printing several 3D metal objects. First, very high aspect ratio (A/R > 20), micron scale, copper pillars in various configuration, upright and arbitrarily bent, then a micron scale 3D object composed of gold and copper. Such a digital printing method could serve the generation of complex, multi-material, micron-scale, 3D materials and novel structures. PMID:26602432

  15. Laser jetting of femto-liter metal droplets for high resolution 3D printed structures

    PubMed Central

    Zenou, M.; Sa’ar, A.; Kotler, Z.

    2015-01-01

    Laser induced forward transfer (LIFT) is employed in a special, high accuracy jetting regime, by adequately matching the sub-nanosecond pulse duration to the metal donor layer thickness. Under such conditions, an effective solid nozzle is formed, providing stability and directionality to the femto-liter droplets which are printed from a large gap in excess of 400 μm. We illustrate the wide applicability of this method by printing several 3D metal objects. First, very high aspect ratio (A/R > 20), micron scale, copper pillars in various configuration, upright and arbitrarily bent, then a micron scale 3D object composed of gold and copper. Such a digital printing method could serve the generation of complex, multi-material, micron-scale, 3D materials and novel structures. PMID:26602432

  16. Laser jetting of femto-liter metal droplets for high resolution 3D printed structures

    NASA Astrophysics Data System (ADS)

    Zenou, M.; Sa'Ar, A.; Kotler, Z.

    2015-11-01

    Laser induced forward transfer (LIFT) is employed in a special, high accuracy jetting regime, by adequately matching the sub-nanosecond pulse duration to the metal donor layer thickness. Under such conditions, an effective solid nozzle is formed, providing stability and directionality to the femto-liter droplets which are printed from a large gap in excess of 400 μm. We illustrate the wide applicability of this method by printing several 3D metal objects. First, very high aspect ratio (A/R > 20), micron scale, copper pillars in various configuration, upright and arbitrarily bent, then a micron scale 3D object composed of gold and copper. Such a digital printing method could serve the generation of complex, multi-material, micron-scale, 3D materials and novel structures.

  17. Method for producing nanostructured metal-oxides

    DOEpatents

    Tillotson, Thomas M.; Simpson, Randall L.; Hrubesh, Lawrence W.; Gash, Alexander

    2006-01-17

    A synthetic route for producing nanostructure metal-oxide-based materials using sol-gel processing. This procedure employs the use of stable and inexpensive hydrated-metal inorganic salts and environmentally friendly solvents such as water and ethanol. The synthesis involves the dissolution of the metal salt in a solvent followed by the addition of a proton scavenger, which induces gel formation in a timely manner. Both critical point (supercritical extraction) and atmospheric (low temperature evaporation) drying may be employed to produce monolithic aerogels and xerogels, respectively. Using this method synthesis of metal-oxide nanostructured materials have been carried out using inorganic salts, such as of Fe.sup.3+, Cr.sup.3+, Al.sup.3+, Ga.sup.3+, In.sup.3+, Hf.sup.4+, Sn.sup.4+, Zr.sup.4+, Nb.sup.5+, W.sup.6+, Pr.sup.3+, Er.sup.3+, Nd.sup.3+, Ce.sup.3+, U.sup.3+ and Y.sup.3+. The process is general and nanostructured metal-oxides from the following elements of the periodic table can be made: Groups 2 through 13, part of Group 14 (germanium, tin, lead), part of Group 15 (antimony, bismuth), part of Group 16 (polonium), and the lanthanides and actinides. The sol-gel processing allows for the addition of insoluble materials (e.g., metals or polymers) to the viscous sol, just before gelation, to produce a uniformly distributed nanocomposites upon gelation. As an example, energetic nanocomposites of Fe.sub.xO.sub.y gel with distributed Al metal are readily made. The compositions are stable, safe, and can be readily ignited to thermitic reaction.

  18. Formation of 3D graphene foams on soft templated metal monoliths.

    PubMed

    Tynan, Michael K; Johnson, David W; Dobson, Ben P; Coleman, Karl S

    2016-07-21

    Graphene foams are leading contenders as frameworks for polymer thermosets, filtration/pollution control and for use as an electrode material in energy storage devices, taking advantage of graphene's high electrical conductivity and the porous structure of the foam. Here we demonstrate a simple synthesis of a macroporous 3D graphene material templated from a dextran/metal salt gel, where the metal was cobalt, nickel, copper, and iron. The gel was annealed to form a metal oxide foam prior to a methane chemical vapour deposition (CVD). Cobalt metal gels were shown to afford the highest quality material as determined by electron microscopy (SEM and TEM) and Raman spectroscopy. PMID:27341076

  19. 3D metal-organic frameworks based on elongated tetracarboxylate building blocks for hydrogen storage.

    PubMed

    Ma, Liqing; Lee, Jeong Yong; Li, Jing; Lin, Wenbin

    2008-05-19

    Two 3D metal-organic frameworks (MOFs) with a new biphenol-derived tetracarboxylate linker and Cu(II) and Zn(II) metal-connecting points were synthesized and characterized by single-crystal X-ray crystallographic studies. The two isostructural MOFs exhibit distorted PtS network topology and show markedly different framework stability. The porosity and hydrogen uptake of the frameworks were determined by gas adsorption experiments. PMID:18416546

  20. Hybrid C-nanotubes/Si 3D nanostructures by one-step growth in a dual-plasma reactor

    NASA Astrophysics Data System (ADS)

    Toschi, Francesco; Orlanducci, Silvia; Guglielmotti, Valeria; Cianchetta, Ilaria; Magni, Corrado; Terranova, Maria Letizia; Pasquali, Matteo; Tamburri, Emanuela; Matassa, Roberto; Rossi, Marco

    2012-06-01

    Hybrid nanostructures consisting of Si polycrystalline nanocones, with an anemone-like termination coated with C-nanotubes bundles, have been generated on a (1 0 0) Si substrate in a dual mode microwave/radio-frequency plasma reactor. The substrate is both heated and bombarded by energetic H ions during the synthesis process. The nanocones growth is explained considering pull of the growing Si nanocrystalline phase along the lines of the electrical field, likely via a molten/recrystallization mechanism. The one-step building of the achieved complex 3D architectures is described in terms of dynamic competition between Si and C nanotubes growth under the peculiar conditions of kinetically driven processes.

  1. Self-aligned metallization on organic semiconductor through 3D dual-layer thermal nanoimprint

    NASA Astrophysics Data System (ADS)

    Jung, Y.; Cheng, X.

    2014-09-01

    High-resolution patterning of metal structures on organic semiconductors is important to the realization of high-performance organic transistors for organic integrated circuit applications. The traditional shadow mask technique has a limited resolution, precluding sub-micron metal structures on organic semiconductors. Thus organic transistors cannot benefit from scaling into the deep sub-micron region to improve their dc and ac performances. In this work, we report an efficient multiple-level metallization on poly (3-hexylthiophene) (P3HT) with a deep sub-micron lateral gap. By using a 3D nanoimprint mold in a dual-layer thermal nanoimprint process, we achieved self-aligned two-level metallization on P3HT. The 3D dual-layer thermal nanoimprint enables the first metal patterns to have suspending side-wings that can clearly define a distance from the second metal patterns. Isotropic and anisotropic side-wing structures can be fabricated through two different schemes. The process based on isotropic side-wings achieves a lateral-gap in the order of 100 nm (scheme 1). A gap of 60 nm can be achieved from the process with anisotropic side-wings (scheme 2). Because of the capability of nanoscale metal patterning on organic semiconductors with high overlay accuracy, this self-aligned metallization technique can be utilized to fabricate high-performance organic metal semiconductor field-effect transistor.

  2. Light-directing chiral liquid crystal nanostructures: from 1D to 3D.

    PubMed

    Bisoyi, Hari Krishna; Li, Quan

    2014-10-21

    Endowing external, remote, and dynamic control to self-organized superstructures with desired functionalities is a principal driving force in the bottom-up nanofabrication of molecular devices. Light-driven chiral molecular switches or motors in liquid crystal (LC) media capable of self-organizing into optically tunable one-dimensional (1D) and three-dimensional (3D) superstructures represent such an elegant system. As a consequence, photoresponsive cholesteric LCs (CLCs), i.e., self-organized 1D helical superstructures, and LC blue phases (BPs), i.e., self-organized 3D periodic cubic lattices, are emerging as a new generation of multifunctional supramolecular 1D and 3D photonic materials in their own right because of their fundamental academic interest and technological significance. These smart stimuli-responsive materials can be facilely fabricated from achiral LC hosts by the addition of a small amount of a light-driven chiral molecular switch or motor. The photoresponsiveness of these materials is a result of both molecular interaction and geometry changes in the chiral molecular switch upon light irradiation. The doped photoresponsive CLCs undergo light-driven pitch modulation and/or helix inversion, which has many applications in color filters, polarizers, all-optical displays, optical lasers, sensors, energy-saving smart devices, and so on. Recently, we have conceptualized and rationally synthesized different light-driven chiral molecular switches that have very high helical twisting powers (HTPs) and exhibit large changes in HTP in different states, thereby enabling wide phototunability of the systems by the addition of very small amounts of the molecular switches into commercially available achiral LCs. The light-driven chiral molecular switches are based on well-recognized azobenzene, dithienylcyclopentene, and spirooxazine derivatives. We have demonstrated high-resolution and lightweight photoaddressable displays without patterned electronics on

  3. Nonlocal optical response in metallic nanostructures.

    PubMed

    Raza, Søren; Bozhevolnyi, Sergey I; Wubs, Martijn; Asger Mortensen, N

    2015-05-13

    This review provides a broad overview of the studies and effects of nonlocal response in metallic nanostructures. In particular, we thoroughly present the nonlocal hydrodynamic model and the recently introduced generalized nonlocal optical response (GNOR) model. The influence of nonlocal response on plasmonic excitations is studied in key metallic geometries, such as spheres and dimers, and we derive new consequences due to the GNOR model. Finally, we propose several trajectories for future work on nonlocal response, including experimental setups that may unveil further effects of nonlocal response. PMID:25893883

  4. 3D filling simulation of micro- and nanostructures in comparison to iso- and variothermal injection moulding trials

    NASA Astrophysics Data System (ADS)

    Rytka, C.; Lungershausen, J.; Kristiansen, P. M.; Neyer, A.

    2016-06-01

    Flow simulations can cut down both costs and time for the development of injection moulded polymer parts with functional surfaces used in life science and optical applications. We simulated the polymer melt flow into 3D micro- and nanostructures with Moldflow and Comsol and compared the results to real iso- and variothermal injection moulding trials below, at and above the transition temperature of the polymer. By adjusting the heat transfer coefficient and the transition temperature in the simulation it was possible to achieve good correlation with experimental findings at different processing conditions (mould temperature, injection velocity) for two polymers, namely polymethylmethacrylate and amorphous polyamide. The macroscopic model can be scaled down in volume and number of elements to save computational time for microstructure simulation and to enable first and foremost the nanostructure simulation, as long as local boundary conditions such as flow front speed are transferred correctly. The heat transfer boundary condition used in Moldflow was further evaluated in Comsol. Results showed that the heat transfer coefficient needs to be increased compared to macroscopic moulding in order to represent interfacial polymer/mould effects correctly. The transition temperature is most important in the packing phase for variothermal injection moulding.

  5. (Plasmonic Metal Core)/(Semiconductor Shell) Nanostructures

    NASA Astrophysics Data System (ADS)

    Fang, Caihong

    Over the past several years, integration of metal nanocrystals that can support localized surface plasmon has been demonstrated as one of the most promising methods to the improvement of the light-harvesting efficiency of semiconductors. Ag and Au nanocrystals have been extensively hybridized with semiconductors by either deposition or anchoring. However, metal nanocrystals tend to aggregate, reshape, detach, or grow into large nanocrystals, leading to a loss of the unique properties seen in the original nanocrystals. Fortunately, core/shell nanostructures, circumventing the aforementioned problems, have been demonstrated to exhibit superior photoactivities. To further improve the light-harvesting applications of (plasmonic metal core)/(semiconductor shell) nanostructures, it is vital to understand the plasmonic and structural evolutions during the preparation processes, design novel hybrid nanostructures, and improve their light-harvesting performances. In this thesis, I therefore studied the plasmonic and structural evolutions during the formation of (Ag core)/(Ag2S shell) nanostructures. Moreover, I also prepared (noble metal core)/(TiO2 shell) nanostructures and investigated their plasmonic properties and photon-harvesting applications. Clear understanding of the sulfidation process can enable fine control of the plasmonic properties as well as the structural composition of Ag/Ag 2S nanomaterials. Therefore, I investigated the plasmonic and structural variations during the sulfidation process of Ag nanocubes both experimentally and numerically. The sulfidation reactions were carried out at both the ensemble and single-particle levels. Electrodynamic simulations were also employed to study the variations of the plasmonic properties and plasmon modes. Both experiment and simulation results revealed that sulfidation initiates at the vertices of Ag nanocubes. Ag nanocubes are then gradually truncated and each nanocube becomes a nanosphere eventually. The cubic

  6. Spectrum simulation of rough and nanostructured targets from their 2D and 3D image by Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Schiettekatte, François; Chicoine, Martin

    2016-03-01

    Corteo is a program that implements Monte Carlo (MC) method to simulate ion beam analysis (IBA) spectra of several techniques by following the ions trajectory until a sufficiently large fraction of them reach the detector to generate a spectrum. Hence, it fully accounts for effects such as multiple scattering (MS). Here, a version of Corteo is presented where the target can be a 2D or 3D image. This image can be derived from micrographs where the different compounds are identified, therefore bringing extra information into the solution of an IBA spectrum, and potentially significantly constraining the solution. The image intrinsically includes many details such as the actual surface or interfacial roughness, or actual nanostructures shape and distribution. This can for example lead to the unambiguous identification of structures stoichiometry in a layer, or at least to better constraints on their composition. Because MC computes in details the trajectory of the ions, it simulates accurately many of its aspects such as ions coming back into the target after leaving it (re-entry), as well as going through a variety of nanostructures shapes and orientations. We show how, for example, as the ions angle of incidence becomes shallower than the inclination distribution of a rough surface, this process tends to make the effective roughness smaller in a comparable 1D simulation (i.e. narrower thickness distribution in a comparable slab simulation). Also, in ordered nanostructures, target re-entry can lead to replications of a peak in a spectrum. In addition, bitmap description of the target can be used to simulate depth profiles such as those resulting from ion implantation, diffusion, and intermixing. Other improvements to Corteo include the possibility to interpolate the cross-section in angle-energy tables, and the generation of energy-depth maps.

  7. Investigation and evaluation of soil heavy metals pollution supported by DTM and 3D visualization

    NASA Astrophysics Data System (ADS)

    Hua, Li; Sui, Haigang; Wang, Juan; Shao, Ya

    2005-10-01

    In this paper, a method that integrates 3D GIS visualization, spatial statistical analysis, spatial database, environmental management & evaluation model for evaluating soil heavy metals pollution is presented. Based on the above method and strategies, taking the nearby farmland in the LongJiao hill mine district of Daye City in the Hubei province as an example, we found that the results using integrative method is superior to traditional method. With the technology of DTM and 3D visualization, the quantity of two heavy metals (Cu,Cd) in investigated six kinds of heavy metals (As, Cr, Pb, Cu, Zn, Cd) was easily found that exceeds the soil environment quality standard GB15618-1995. The research discovers the new idea and method can improve the efficiency and precision comparing to traditional heavy metals investigation and evaluation method. Different with traditional 2D representation mode, the new method integrated 3D visualization can visually represent and adequately evaluate soil heavy metals pollution distribution situation in the mineral area.

  8. Formation of 3D graphene foams on soft templated metal monoliths

    NASA Astrophysics Data System (ADS)

    Tynan, Michael K.; Johnson, David W.; Dobson, Ben P.; Coleman, Karl S.

    2016-07-01

    Graphene foams are leading contenders as frameworks for polymer thermosets, filtration/pollution control and for use as an electrode material in energy storage devices, taking advantage of graphene's high electrical conductivity and the porous structure of the foam. Here we demonstrate a simple synthesis of a macroporous 3D graphene material templated from a dextran/metal salt gel, where the metal was cobalt, nickel, copper, and iron. The gel was annealed to form a metal oxide foam prior to a methane chemical vapour deposition (CVD). Cobalt metal gels were shown to afford the highest quality material as determined by electron microscopy (SEM and TEM) and Raman spectroscopy.Graphene foams are leading contenders as frameworks for polymer thermosets, filtration/pollution control and for use as an electrode material in energy storage devices, taking advantage of graphene's high electrical conductivity and the porous structure of the foam. Here we demonstrate a simple synthesis of a macroporous 3D graphene material templated from a dextran/metal salt gel, where the metal was cobalt, nickel, copper, and iron. The gel was annealed to form a metal oxide foam prior to a methane chemical vapour deposition (CVD). Cobalt metal gels were shown to afford the highest quality material as determined by electron microscopy (SEM and TEM) and Raman spectroscopy. Electronic supplementary information (ESI) available: Raman, EDX, PXRD, TGA, electrical conductivity data and SEM. See DOI: 10.1039/c6nr02455f

  9. METALLIC AND HYBRID NANOSTRUCTURES: FUNDAMENTALS AND APPLICATIONS

    SciTech Connect

    Murph, S.

    2012-05-02

    This book chapter presents an overview of research conducted in our laboratory on preparation, optical and physico-chemical properties of metallic and nanohybrid materials. Metallic nanoparticles, particularly gold, silver, platinum or a combination of those are the main focus of this review manuscript. These metallic nanoparticles were further functionalized and used as templates for creation of complex and ordered nanomaterials with tailored and tunable structural, optical, catalytic and surface properties. Controlling the surface chemistry on/off metallic nanoparticles allows production of advanced nanoarchitectures. This includes coupled or encapsulated core-shell geometries, nano-peapods, solid or hollow, monometallic/bimetallic, hybrid nanoparticles. Rational assemblies of these nanostructures into one-, two- and tridimensional nano-architectures is described and analyzed. Their sensing, environmental and energy related applications are reviewed.

  10. Magnetization reversal in 3D nano-structures of different shapes

    NASA Astrophysics Data System (ADS)

    Blachowicz, T.; Ehrmann, A.

    2016-04-01

    Magnetic nano-particles have been intensively studied during the last decade due to their potential utilization in various applications. An important topic is the dependence of magnetic properties on the exact samples shape. After demonstrating the influence of shape distortions in magnetic nano half-spheres on magnetization reversal processes and hysteresis shapes, a series of different 3D nano-objects from permalloy with shape modifications has been examined with respect to their magnetic properties. Modifications are performed by cutting parts of diverse samples between the extrema of a cuboid and a half-sphere. Simulations of these samples have been performed by Magpar, using external magnetic fields along two different axes, swept with two different speeds. Depending on the original particle shape and its modifications, several phenomena can be found: Cutting a hole in a cuboid can switch the hard axis from out-of-plane to the in-plane direction. In some nano-particles, strong oscillations occur which can be suppressed by appropriate shape modifications. In some of the nano-objects, the magnetization reversal mechanism is completely altered by a change in the field sweeping speed. The article gives an overview of the different possibilities to tailor magnetic properties of nano-systems.

  11. A facile route for 3D aerogels from nanostructured 1D and 2D materials

    PubMed Central

    Jung, Sung Mi; Jung, Hyun Young; Dresselhaus, Mildred S.; Jung, Yung Joon; Kong, Jing

    2012-01-01

    Aerogels have numerous applications due to their high surface area and low densities. However, creating aerogels from a large variety of materials has remained an outstanding challenge. Here, we report a new methodology to enable aerogel production with a wide range of materials. The method is based on the assembly of anisotropic nano-objects (one-dimensional (1D) nanotubes, nanowires, or two-dimensional (2D) nanosheets) into a cross-linking network from their colloidal suspensions at the transition from the semi-dilute to the isotropic concentrated regime. The resultant aerogels have highly porous and ultrafine three-dimensional (3D) networks consisting of 1D (Ag, Si, MnO2, single-walled carbon nanotubes (SWNTs)) and 2D materials (MoS2, graphene, h-BN) with high surface areas, low densities, and high electrical conductivities. This method opens up a facile route for aerogel production with a wide variety of materials and tremendous opportunities for bio-scaffold, energy storage, thermoelectric, catalysis, and hydrogen storage applications. PMID:23152940

  12. Projection-based metal-artifact reduction for industrial 3D X-ray computed tomography.

    PubMed

    Amirkhanov, Artem; Heinzl, Christoph; Reiter, Michael; Kastner, Johann; Gröller, M Eduard

    2011-12-01

    Multi-material components, which contain metal parts surrounded by plastic materials, are highly interesting for inspection using industrial 3D X-ray computed tomography (3DXCT). Examples of this application scenario are connectors or housings with metal inlays in the electronic or automotive industry. A major problem of this type of components is the presence of metal, which causes streaking artifacts and distorts the surrounding media in the reconstructed volume. Streaking artifacts and dark-band artifacts around metal components significantly influence the material characterization (especially for the plastic components). In specific cases these artifacts even prevent a further analysis. Due to the nature and the different characteristics of artifacts, the development of an efficient artifact-reduction technique in reconstruction-space is rather complicated. In this paper we present a projection-space pipeline for metal-artifacts reduction. The proposed technique first segments the metal in the spatial domain of the reconstructed volume in order to separate it from the other materials. Then metal parts are forward-projected on the set of projections in a way that metal-projection regions are treated as voids. Subsequently the voids, which are left by the removed metal, are interpolated in the 2D projections. Finally, the metal is inserted back into the reconstructed 3D volume during the fusion stage. We present a visual analysis tool, allowing for interactive parameter estimation of the metal segmentation. The results of the proposed artifact-reduction technique are demonstrated on a test part as well as on real world components. For these specimens we achieve a significant reduction of metal artifacts, allowing an enhanced material characterization. PMID:22034338

  13. Two step formation of metal aggregates by surface X-ray radiolysis under Langmuir monolayers: 2D followed by 3D growth

    PubMed Central

    Mukherjee, Smita; Fauré, Marie-Claude; Goldmann, Michel

    2015-01-01

    Summary In order to form a nanostructured metallic layer below a Langmuir monolayer, radiolysis synthesis was carried out in an adapted geometry that we call surface X-ray radiolysis. In this procedure, an X-ray beam produced by a synchrotron beamline intercepts the surface of an aqueous metal-ion solution covered by a Langmuir monolayer at an angle of incidence below the critical angle for total internal reflection. Underneath the organic layer, the X-ray beam induces the radiolytic synthesis of a nanostructured metal–organic layer whose ultrathin thickness is defined by the vertical X-ray penetration depth. We have shown that increasing the X-ray flux on the surface, which considerably enhances the kinetics of the silver layer formation, results in a second growth regime of silver nanocrystals. Here the formation of the oriented thin layer is followed by the appearance of a 3D powder of silver clusters. PMID:26734531

  14. Radon transform based automatic metal artefacts generation for 3D threat image projection

    NASA Astrophysics Data System (ADS)

    Megherbi, Najla; Breckon, Toby P.; Flitton, Greg T.; Mouton, Andre

    2013-10-01

    Threat Image Projection (TIP) plays an important role in aviation security. In order to evaluate human security screeners in determining threats, TIP systems project images of realistic threat items into the images of the passenger baggage being scanned. In this proof of concept paper, we propose a 3D TIP method which can be integrated within new 3D Computed Tomography (CT) screening systems. In order to make the threat items appear as if they were genuinely located in the scanned bag, appropriate CT metal artefacts are generated in the resulting TIP images according to the scan orientation, the passenger bag content and the material of the inserted threat items. This process is performed in the projection domain using a novel methodology based on the Radon Transform. The obtained results using challenging 3D CT baggage images are very promising in terms of plausibility and realism.

  15. Computational engineering of metallic nanostructures and nanomachines.

    PubMed

    Rieth, M; Schommers, W

    2002-12-01

    Small structures with dimensions in the nanometer regime play an important role within a lot of modern technological branches like, for example, genetics, chip fabrication, material science, medicine, or chemistry. While highly sophisticated characterization methods would be necessary to study such nanostructures, computational methods and models have made their entrance into the field of nanotechnology. The present work gives an overview of the problems connected with quantum mechanics, many-particle systems, and nanophysical models. Further, the application of molecular dynamics (MD)--a typical computational method suitable for modelling at the nanolevel--is introduced and outlined. The setup and use of specific MD models, advanced computation techniques, and efficient algorithms are discussed, while the focus is laid on the subjects nanodesign and nanoengineering which are demonstrated for the example of metallic nanostructures. Finally, the introduced techniques and methods are applied to stability studies of theoretical nanomachines. PMID:12908434

  16. Uniform metal patterning on micromachined 3D surfaces using multistep exposure of UV light

    NASA Astrophysics Data System (ADS)

    Suriadi, Arief; Berauer, Frank; Yasunaga, Akari; Pan, Alfred I.; Vander Plas, Hubert A.

    2002-07-01

    Focal depth limitations prevent use of normal lithography tools and processes on three-dimensional structures. A relatively little known form of uniform metal trace patterning over extreme 3-D structured wafers by a multi-step exposure method, called stitching technology, has recently been developed by Hewlett-Packard Company, with equipment support from the Ultratech Stepper Company, the result of which is being reported in this paper. The basic idea is to slice the metal lines to be patterned into topographic layers that can each be exposed in one step. Patches of patterned metal lines can thus be stitch-ed to one another (thus, the term stitching). Exposure of one photo-resist layer by stitching takes several individual exposures at different focus planes. A patent has been applied for this method on behalf of the Hewlett Packard Company. Results of the present investigation demonstrate the superior uniformity of metal trace pattern over 350-um deep trenches produced by multi-step exposure, as compared to the conventional single-step exposure method, typically used on planar semiconductor wafer. The integrated method offers an enabling technology for patterning of extensive topography typically required for a multitude of MEMS structures and designs, novel interconnect structures as well as advanced packaging applications. The method is simple, accurate and relatively low-cost in comparison with other 3-D exposure techniques available and capable of 3-D structure patterning.

  17. Hydrothermal synthesis of a 3D double-sided comb-like ZnO nanostructure and its growth mechanism analysis.

    PubMed

    Li, Wenqiang; Gao, Shiyong; Li, Lin; Jiao, Shujie; Li, Hongtao; Wang, Jinzhong; Yu, Qingjiang; Zhang, Yong; Wang, Dongbo; Zhao, Liancheng

    2016-07-01

    Self-assembly of two-dimensional (2D) nanosheets and one-dimensional (1D) nanorods into three-dimensional (3D) double-sided comb-like ZnO nanostructures has been successfully performed via a simple one-step hydrothermal method on Si and ITO substrates. It is found that the thickness of the ZnO seeds plays a vital role in the formation of 3D double-sided comb-like ZnO. PMID:27279279

  18. Melting points and chemical bonding properties of 3d transition metal elements

    NASA Astrophysics Data System (ADS)

    Takahara, Wataru

    2014-08-01

    The melting points of 3d transition metal elements show an unusual local minimal peak at manganese across Period 4 in the periodic table. The chemical bonding properties of scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper are investigated by the DV-Xα cluster method. The melting points are found to correlate with the bond overlap populations. The chemical bonding nature therefore appears to be the primary factor governing the melting points.

  19. Chemical Dealloying Derived 3D Porous Current Collector for Li Metal Anodes.

    PubMed

    Yun, Qinbai; He, Yan-Bing; Lv, Wei; Zhao, Yan; Li, Baohua; Kang, Feiyu; Yang, Quan-Hong

    2016-08-01

    A 3D porous Cu current collector is fabricated through chemical dealloying from a commerial Cu-Zn alloy tape. The interlinked porous framework naturally integrated can accommodate Li deposition, suppressing dendrite growth and alleviating the huge volume change during cycling. The Li metal anode combined with such a porous Cu collector demonstrates excellent performance and commerial potentials in Li-based secondary batteries. PMID:27219349

  20. A theoretical study of the structure and stability of borohydride on 3d transition metals

    NASA Astrophysics Data System (ADS)

    Arevalo, Ryan Lacdao; Escaño, Mary Clare Sison; Gyenge, Elod; Kasai, Hideaki

    2012-12-01

    The adsorption of borohydride on 3d transition metals (Cr, Mn, Fe, Co, Ni and Cu) was studied using first principles calculations within spin-polarized density functional theory. Magnetic effect on the stability of borohydride is noted. Molecular adsorption is favorable on Co, Ni and Cu, which is characterized by the strong s-dzz hybridization of the adsorbate-substrate states. Dissociated adsorption structure yielding one or two H adatom fragments on the surface is observed for Cr, Mn and Fe.

  1. Fabrication and characterization of metal nanostructures on metal substrates

    NASA Astrophysics Data System (ADS)

    Nikov, Ru. G.; Nedyalkov, N. N.; Atanasov, P. A.; Delaporte, Ph.; Grojo, D.

    2015-01-01

    In this paper we show an experimental procedure for fabrication of metal nanoparticle arrays on metal substrates. The nanostructures are fabricated by laser processing of thin metal films. The films are deposited on the metal substrates by classical PLD technology. The as deposited films are then annealed by nanosecond pulses delivered from a THG Nd:YAG laser system (λ = 355 nm). At certain conditions, the laser treatment leads to a formation of discrete nanoparticle structure on the substrate surface. The optical properties of samples fabricated at different conditions and having different characteristics of the nanostructures are examined by optical spectroscopy measurement. Such analysis shows that the optical spectra of the obtained nanostructures are characterized by plasmon excitation. Finite difference time domain (FDTD) model is used for theoretical description of the near field optical properties of the fabricated nanoparticle arrays. The simulation demonstrates high efficiency of the fabricated structures in enhancement of the near field intensity. The great enhancement observed in the Raman spectra of Rhodamine 6G deposited on the fabricated samples makes such structures very appropriate for applications in Surface Enhanced Raman Spectroscopy (SERS). The produced systems can be also applied in plasmonic solar cells (PSC).

  2. Radiation damage in nanostructured metallic films

    NASA Astrophysics Data System (ADS)

    Yu, Kaiyuan

    High energy neutron and charged particle radiation cause microstructural and mechanical degradation in structural metals and alloys, such as phase segregation, void swelling, embrittlement and creep. Radiation induced damages typically limit nuclear materials to a lifetime of about 40 years. Next generation nuclear reactors require materials that can sustain over 60 - 80 years. Therefore it is of great significance to explore new materials with better radiation resistance, to design metals with favorable microstructures and to investigate their response to radiation. The goals of this thesis are to study the radiation responses of several nanostructured metallic thin film systems, including Ag/Ni multilayers, nanotwinned Ag and nanocrystalline Fe. Such systems obtain high volume fraction of boundaries, which are considered sinks to radiation induced defects. From the viewpoint of nanomechanics, it is of interest to investigate the plastic deformation mechanisms of nanostructured films, which typically show strong size dependence. By controlling the feature size (layer thickness, twin spacing and grain size), it is applicable to picture a deformation mechanism map which also provides prerequisite information for subsequent radiation hardening study. And from the viewpoint of radiation effects, it is of interest to explore the fundamentals of radiation response, to examine the microstructural and mechanical variations of irradiated nanometals and to enrich the design database. More importantly, with the assistance of in situ techniques, it is appealing to examine the defect generation, evolution, annihilation, absorption and interaction with internal interfaces (layer interfaces, twin boundaries and grain boundaries). Moreover, well-designed nanostructures can also verify the speculation that radiation induced defect density and hardening show clear size dependence. The focus of this thesis lies in the radiation response of Ag/Ni multilayers and nanotwinned Ag

  3. Forcing Ferromagnetic Coupling Between Rare-Earth-Metal and 3d Ferromagnetic Films

    NASA Astrophysics Data System (ADS)

    Sanyal, Biplab; Antoniak, Carolin; Burkert, Till; Krumme, Bernhard; Warland, Anne; Stromberg, Frank; Praetorius, Christian; Fauth, Kai; Wende, Heiko; Eriksson, Olle

    2010-04-01

    Using density functional calculations, we have studied the magnetic properties of nanocomposites composed of rare-earth-metal elements in contact with 3d transition metals (Fe and Cr). We demonstrate the possibility to obtain huge magnetic moments in such nanocomposites, of order 10μB/rare-earth-metalatom, with a potential to reach the maximum magnetic moment of Fe-Co alloys at the top of the so-called Slater-Pauling curve. A first experimental proof of concept is given by thin-film synthesis of Fe/Gd and Fe/Cr/Gd nanocomposites, in combination with x-ray magnetic circular dichroism.

  4. Process for the preparation of metal-containing nanostructured films

    NASA Technical Reports Server (NTRS)

    Lu, Yunfeng (Inventor); Wang, Donghai (Inventor)

    2006-01-01

    Metal-containing nanostructured films are prepared by electrodepositing a metal-containing composition within the pores of a mesoporous silica template to form a metal-containing silica nanocomposite. The nanocomposite is annealed to strengthen the deposited metal-containing composition. The silica is then removed from the nanocomposite, e.g., by dissolving the silica in an etching solution to provide a self-supporting metal-containing nanostructured film. The nanostructured films have a nanowire or nanomesh architecture depending on the pore structure of the mesoporous silica template used to prepare the films.

  5. Metal-polymer composites comprising nanostructures and applications thereof

    SciTech Connect

    Wang, Hsing-Lin; Jeon, Sea Ho; Mack, Nathan H.

    2011-08-02

    Metal-polymer composites, and methods of making and use thereof, said composites comprising a thermally-cured dense polyaniline substrate; an acid dopant; and, metal nanostructure deposits wherein the deposits have a morphology dependent upon the acid dopant.

  6. Metal-polymer composites comprising nanostructures and applications thereof

    SciTech Connect

    Wang, Hsing-Lin; Jeon, Sea Ho; Mack, Nathan H.

    2012-04-03

    Metal-polymer composites, and methods of making and use thereof, said composites comprising a thermally-cured dense polyaniline substrate; an acid dopant; and, metal nanostructure deposits wherein the deposits have a morphology dependent upon the acid dopant.

  7. Surface plasmon polaritons in artificial metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Briscoe, Jayson Lawrence

    Surface plasmon polaritons have been the focus of intense research due to their many unique properties such as high electromagnetic field localization, extreme sensitivity to surface conditions, and subwavelength confinement of electromagnetic waves. The area of potential impact is vast and includes promising advancements in photonic circuits, high speed photodetection, hyperspectral imaging, spectroscopy, enhanced solar cells, ultra-small scale lithography, and microscopy. My research has focused on utilizing these properties to design and demonstrate new phenomena and implement real-world applications using artificial metallic nanostructures. Artificial metallic nanostructures employed during my research begin as thin planar gold films which are then lithographically patterned according to previously determined dimensions. The result is a nanopatterned device which can excite surface plasmon polaritons on its surface under specific conditions. Through my research I characterized the optical properties of these devices for further insight into the interesting properties of surface plasmon polaritons. Exploration of these properties led to advancements in biosensing, development of artificial media to enhance and control light-matter interactions at the nanoscale, and hybrid plasmonic cavities. Demonstrations from these advancements include: label-free immunosensing of Plasmodium in a whole blood lysate, low part-per-trillion detection of microcystin-LR, enhanced refractive index sensitivity of novel resonant plasmonic devices, a defect-based plasmonic crystal, spontaneous emission modification of colloidal quantum dots, and coupling of plasmonic and optical Fabry-Perot resonant modes in a hybrid cavity.

  8. Low-cost impact detection and location for automated inspections of 3D metallic based structures.

    PubMed

    Morón, Carlos; Portilla, Marina P; Somolinos, José A; Morales, Rafael

    2015-01-01

    This paper describes a new low-cost means to detect and locate mechanical impacts (collisions) on a 3D metal-based structure. We employ the simple and reasonably hypothesis that the use of a homogeneous material will allow certain details of the impact to be automatically determined by measuring the time delays of acoustic wave propagation throughout the 3D structure. The location of strategic piezoelectric sensors on the structure and an electronic-computerized system has allowed us to determine the instant and position at which the impact is produced. The proposed automatic system allows us to fully integrate impact point detection and the task of inspecting the point or zone at which this impact occurs. What is more, the proposed method can be easily integrated into a robot-based inspection system capable of moving over 3D metallic structures, thus avoiding (or minimizing) the need for direct human intervention. Experimental results are provided to show the effectiveness of the proposed approach. PMID:26029951

  9. Low-Cost Impact Detection and Location for Automated Inspections of 3D Metallic Based Structures

    PubMed Central

    Morón, Carlos; Portilla, Marina P.; Somolinos, José A.; Morales, Rafael

    2015-01-01

    This paper describes a new low-cost means to detect and locate mechanical impacts (collisions) on a 3D metal-based structure. We employ the simple and reasonably hypothesis that the use of a homogeneous material will allow certain details of the impact to be automatically determined by measuring the time delays of acoustic wave propagation throughout the 3D structure. The location of strategic piezoelectric sensors on the structure and an electronic-computerized system has allowed us to determine the instant and position at which the impact is produced. The proposed automatic system allows us to fully integrate impact point detection and the task of inspecting the point or zone at which this impact occurs. What is more, the proposed method can be easily integrated into a robot-based inspection system capable of moving over 3D metallic structures, thus avoiding (or minimizing) the need for direct human intervention. Experimental results are provided to show the effectiveness of the proposed approach. PMID:26029951

  10. Mechanical behavior of carbon nanotube and graphene junction as a building block for 3D carbon nanostructures

    NASA Astrophysics Data System (ADS)

    Moradi, Mina; Aghazadeh Mohandesi, Jamshid

    2015-11-01

    The incorporation of defects in junction area of 1D and 2D carbon nanostructures has a major impact on properties of their 3D structures. In the present study, molecular dynamics simulation is utilized to examine the mechanical behavior of graphene sheet (GS) in carbon nanotube (CNT)-GS junctions. The tensile load was applied along the GS in connection with CNTs of different chiralities. The adaptive intermolecular reactive empirical bond order potential was chosen to model C-C interactions. It provided a reliable model for CNT, GS and their junctions. The results revealed that the connection of CNT to the GS with a hole could improve the mechanical properties of defective GS, which appeared to be independent of CNT type. It was found that the high strength C-C bonds postpone the crack propagation and motivates new crack nucleation. When a hole or CNT placed on the GS, it caused stress concentration, exactly along a line on its side. The lower mechanical properties were consequently associated with crack nucleation and propagation on both sides in a way that cracks encountered each other during the failure; while, the cracks in pristine GS propagate parallel to each other and could not encounter each other.

  11. 3D nanostructured inkjet printed graphene via UV-pulsed laser irradiation enables paper-based electronics and electrochemical devices.

    PubMed

    Das, Suprem R; Nian, Qiong; Cargill, Allison A; Hondred, John A; Ding, Shaowei; Saei, Mojib; Cheng, Gary J; Claussen, Jonathan C

    2016-09-21

    Emerging research on printed and flexible graphene-based electronics is beginning to show tremendous promise for a wide variety of fields including wearable sensors and thin film transistors. However, post-print annealing/reduction processes that are necessary to increase the electrical conductivity of the printed graphene degrade sensitive substrates (e.g., paper) and are whole substrate processes that are unable to selectively anneal/reduce only the printed graphene-leaving sensitive device components exposed to damaging heat or chemicals. Herein a pulsed laser process is introduced that can selectively irradiate inkjet printed reduced graphene oxide (RGO) and subsequently improve the electrical conductivity (Rsheet∼0.7 kΩ□(-1)) of printed graphene above previously published reports. Furthermore, the laser process is capable of developing 3D petal-like graphene nanostructures from 2D planar printed graphene. These visible morphological changes display favorable electrochemical sensing characteristics-ferricyanide cyclic voltammetry with a redox peak separation (ΔEp) ≈ 0.7 V as well as hydrogen peroxide (H2O2) amperometry with a sensitivity of 3.32 μA mM(-1) and a response time of <5 s. Thus this work paves the way for not only paper-based electronics with graphene circuits, it enables the creation of low-cost and disposable graphene-based electrochemical electrodes for myriad applications including sensors, biosensors, fuel cells, and theranostic devices. PMID:27510913

  12. Morphology control of nanostructures via surface reaction of metal nanodroplets.

    PubMed

    Niu, K Y; Yang, J; Kulinich, S A; Sun, J; Li, H; Du, X W

    2010-07-21

    We report on the controllable synthesis of diverse nanostructures using laser ablation of a metal target in a liquid medium. The nanodroplets generated by laser ablation react with the liquid and produce various nanostructures, such as hollow nanoparticles, core-shell nanoparticles, heterostructures, nanocubes, and ordered arrays. A millisecond laser with low power density is essential for obtaining such metal nanodroplets, while the target material, the reactivity of liquid medium, and the laser frequency are decisive for controlling the morphology and size of the nanostructures produced. This green and powerful technique can be extended to different material systems for obtaining various nanostructures. PMID:20572659

  13. Plasmonic hydrogen sensing with nanostructured metal hydrides.

    PubMed

    Wadell, Carl; Syrenova, Svetlana; Langhammer, Christoph

    2014-12-23

    In this review, we discuss the evolution of localized surface plasmon resonance and surface plasmon resonance hydrogen sensors based on nanostructured metal hydrides, which has accelerated significantly during the past 5 years. We put particular focus on how, conceptually, plasmonic resonances can be used to study metal-hydrogen interactions at the nanoscale, both at the ensemble and at the single-nanoparticle level. Such efforts are motivated by a fundamental interest in understanding the role of nanosizing on metal hydride formation processes in the quest to develop efficient solid-state hydrogen storage materials with fast response times, reasonable thermodynamics, and acceptable long-term stability. Therefore, a brief introduction to the thermodynamics of metal hydride formation is also given. However, plasmonic hydrogen sensors not only are of academic interest as research tool in materials science but also are predicted to find more practical use as all-optical gas detectors in industrial and medical applications, as well as in a future hydrogen economy, where hydrogen is used as a carbon free energy carrier. Therefore, the wide range of different plasmonic hydrogen sensor designs already available is reviewed together with theoretical efforts to understand their fundamentals and optimize their performance in terms of sensitivity. In this context, we also highlight important challenges to be addressed in the future to take plasmonic hydrogen sensors from the laboratory to real applications in devices, including poisoning/deactivation of the active materials, sensor lifetime, and cross-sensitivity toward other gas species. PMID:25427244

  14. Template-Free 3D Microprinting of Metals Using a Force-Controlled Nanopipette for Layer-by-Layer Electrodeposition.

    PubMed

    Hirt, Luca; Ihle, Stephan; Pan, Zhijian; Dorwling-Carter, Livie; Reiser, Alain; Wheeler, Jeffrey M; Spolenak, Ralph; Vörös, János; Zambelli, Tomaso

    2016-03-23

    A novel 3D printing method for voxel-by-voxel metal printing is presented. Hollow atomic force microscopy (AFM) cantilevers are used to locally supply metal ions in an electrochemical cell, enabling a localized electroplating reaction. By exploiting the deflection feedback of these probes, electrochemical 3D metal printing is, for the first time, demonstrated in a layer-by-layer fashion, enabling the fabrication of arbitrary-shaped geometries. PMID:26783090

  15. Simulation of the impact of 3-D porosity distribution in metallic U-10Zr fuels

    NASA Astrophysics Data System (ADS)

    Yun, Di; Yacout, Abdellatif M.; Stan, Marius; Bauer, Theodore H.; Wright, Arthur E.

    2014-05-01

    Evolution of porosity generated in metallic U-Zr fuel irradiated in fast spectrum reactors leads to changes in fuel properties and impacts important phenomena such as heat transport and constituent redistribution. The porosity is generated as a result of the accumulation of fission gases and is affected by the possible bond sodium infiltration into the fuel. Typically, the impact of porosity development on properties, such as thermal conductivity, is accounted for through empirical correlations that are dependent on porosity and infiltrated sodium fractions. Currently available simulation tools make it possible to take into account fuel 3-D porosity distributions, potentially eliminating the need for such correlations. This development allows for a more realistic representation of the porosity evolution in metallic fuel and creates a framework for truly mechanistic fuel development models. In this work, COMSOL multi-physics simulation platform is used to model 3-D porosity distributions and simulate heat transport in metallic U-10Zr fuel. Available experimental data regarding microstructural evolution of fuel that was irradiated in EBR-II and associated phase stability information are used to guide the simulation. The impact of changes in porosity characteristics on material properties is estimated and the results are compared with calculated temperature distributions. The simulations demonstrate the developed capability and importance of accounting for detailed porosity distribution features for accurate fuel performance evaluation.

  16. Inclined nanoimprinting lithography-based 3D nanofabrication

    NASA Astrophysics Data System (ADS)

    Liu, Zhan; Bucknall, David G.; Allen, Mark G.

    2011-06-01

    We report a 'top-down' 3D nanofabrication approach combining non-conventional inclined nanoimprint lithography (INIL) with reactive ion etching (RIE), contact molding and 3D metal nanotransfer printing (nTP). This integration of processes enables the production and conformal transfer of 3D polymer nanostructures of varying heights to a variety of other materials including a silicon-based substrate, a silicone stamp and a metal gold (Au) thin film. The process demonstrates the potential of reduced fabrication cost and complexity compared to existing methods. Various 3D nanostructures in technologically useful materials have been fabricated, including symmetric and asymmetric nanolines, nanocircles and nanosquares. Such 3D nanostructures have potential applications such as angle-resolved photonic crystals, plasmonic crystals and biomimicking anisotropic surfaces. This integrated INIL-based strategy shows great promise for 3D nanofabrication in the fields of photonics, plasmonics and surface tribology.

  17. 3d Transition Metal Adsorption Induced the valley-polarized Anomalous Hall Effect in Germanene

    NASA Astrophysics Data System (ADS)

    Zhou, P.; Sun, L. Z.

    2016-06-01

    Based on DFT + U and Berry curvature calculations, we study the electronic structures and topological properties of 3d transition metal (TM) atom (from Ti to Co) adsorbed germanene (TM-germanene). We find that valley-polarized anomalous Hall effect (VAHE) can be realized in germanene by adsorbing Cr, Mn, or Co atoms on its surface. A finite valley Hall voltage can be easily detected in their nanoribbon, which is important for valleytronics devices. Moreover, different valley-polarized current and even reversible valley Hall voltage can be archived by shifting the Fermi energy of the systems. Such versatile features of the systems show potential in next generation electronics devices.

  18. 3D laser scanning microscopy of hypervelocity impact features in metal and aerogel targets

    NASA Astrophysics Data System (ADS)

    Hillier, J. K.; Postberg, F.; Price, M. C.; Trieloff, M.; Li, Y. W.; Srama, R.

    2012-09-01

    We present the results of a study into the mapping of hypervelocity impact features using a Keyence VK-X200 3D laser scanning microscope. The impact features observed are impact craters in a variety of different metal targets (Al, Au and Cu) and impact tracks in aerogel targets, similar to those used in the Stardust mission. Differences in crater morphology between different target materials and impact velocities, as well as differences in track depth and diameter in aerogel, for particles of known constant dimensions, are discussed.

  19. Synthesis of graphitic nanostructures on noble metals

    NASA Astrophysics Data System (ADS)

    Parmentier, Amelie

    In this research, two subjects are studied: the growth of graphene from various catalysts with RF-CVD and the growth of graphitic nanostructures from gold-decorated graphene with RF-CVD. In the first topic, various catalysts are made with magnesium oxide and metal nanoparticles: iron, silver and gold. Using a radio-frequency generator, these catalysts are heated and placed in contact with three gases (argon, hydrogen and methane). By controlling various parameters, graphene synthesis can happen. The results are analyzed with Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermo-gravimetrical analysis (TGA), and X-ray diffraction (XRD). In the second topic, commercial graphene is functionalized and decorated with different sizes of gold nanoparticles (1.8nm, 5nm, 10nm and 50nm). Using the RF-CVD process, these samples are heated at different temperatures (500°C, 650°C and 800°C). Depending on the parameters, different kinds of graphitic nanostructures are synthesized. Results are analyzed with Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy.

  20. Bi–Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

    SciTech Connect

    Shi, Fa-Nian; Rosa Silva, Ana; Bian, Liang

    2015-05-15

    A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn–Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi{sub 2}O(1,3,5-BTC){sub 2}]{sub n} (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi{sub 4}O{sub 2}(COO){sub 12} clusters which are further connected to Mn(COO){sub 6} fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of (4{sup 13}.6{sup 2})(4{sup 13}.6{sup 8})(4{sup 16}.6{sup 5})(4{sup 18}.6{sup 10})(4{sup 22}.6{sup 14})(4{sup 3}) corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones. - Graphical abstract: This metal organic framework (MOF) is the essence of a 2D metal organic oxide (MOO). - Highlights: • New concept of metal organic oxide (MOO) was defined and made difference from metal organic framework. • New MOO of MOOMnBi was synthesized by hydrothermal method. • Crystal structure of MOOMnBi was determined by single crystal X-ray analysis. • The catalytic activity of MOOMnBi was studied showing reusable after 2 cycles.

  1. The Development of Metal Oxide Chemical Sensing Nanostructures

    NASA Technical Reports Server (NTRS)

    Hunter, G. W.; VanderWal,R. L.; Xu, J. C.; Evans, L. J.; Berger, G. M.; Kulis, M. J.

    2008-01-01

    This paper discusses sensor development based on metal oxide nanostructures and microsystems technology. While nanostructures such as nanowires show significant potential as enabling materials for chemical sensors, a number of significant technical challenges remain. This paper discusses development to address each of these technical barriers: 1) Improved contact and integration of the nanostructured materials with microsystems in a sensor structure; 2) Control of nanostructure crystallinity to allow control of the detection mechanism; and 3) Widening the range of gases that can be detected by fabricating multiple nanostructured materials. A sensor structure composed of three nanostructured oxides aligned on a single microsensor has been fabricated and tested. Results of this testing are discussed and future development approaches are suggested. It is concluded that while this work lays the foundation for further development, these are the beginning steps towards realization of repeatable, controlled sensor systems using oxide based nanostructures.

  2. Fabrication of dielectric and metallo-dielectric 3D nanostructures by direct laser writing and electroless plating

    NASA Astrophysics Data System (ADS)

    Radke, André; Wolff, Frank; Giessen, Harald; Klotzbücher, Thomas

    2010-02-01

    Direct laser writing via two-photon absorption allows the fabrication of three-dimensional dielectric structures with submicron resolution by tightly focusing ultrashort laser pulses into a photo-sensitive material with a high-resolution microscope objective and scanning the laser focus relative to the material. Woodpile photonic crystals fabricated with this method show a characteristic dip in transmission at near-infrared wavelengths. The spectral position of this transmission dip scales with the grating period of the fabricated crystals. Metallo-dielectric structures can be obtained by first fabricating dielectric templates with direct laser writing and subsequently coating the templates with a thin conformal metal film by electroless plating. Contiguous and conducting silver films can be deposited even on convoluted 3D geometries.

  3. Nanostructures from hydrogen implantation of metals.

    SciTech Connect

    McWatters, Bruce Ray; Causey, Rion A.; DePuit, Ryan J.; Yang, Nancy Y. C.; Ong, Markus D.

    2009-09-01

    This study investigates a pathway to nanoporous structures created by hydrogen implantation in aluminum. Previous experiments for fusion applications have indicated that hydrogen and helium ion implantations are capable of producing bicontinuous nanoporous structures in a variety of metals. This study focuses specifically on hydrogen and helium implantations of aluminum, including complementary experimental results and computational modeling of this system. Experimental results show the evolution of the surface morphology as the hydrogen ion fluence increases from 10{sup 17} cm{sup -2} to 10{sup 18} cm{sup -2}. Implantations of helium at a fluence of 10{sup 18} cm{sup -2} produce porosity on the order of 10 nm. Computational modeling demonstrates the formation of alanes, their desorption, and the resulting etching of aluminum surfaces that likely drives the nanostructures that form in the presence of hydrogen.

  4. Barrier-free subsurface incorporation of 3 d metal atoms into Bi(111) films

    NASA Astrophysics Data System (ADS)

    Klein, C.; Vollmers, N. J.; Gerstmann, U.; Zahl, P.; Lükermann, D.; Jnawali, G.; Pfnür, H.; Tegenkamp, C.; Sutter, P.; Schmidt, W. G.; Horn-von Hoegen, M.

    2015-05-01

    By combining scanning tunneling microscopy with density functional theory it is shown that the Bi (111 ) surface provides a well-defined incorporation site in the first bilayer that traps highly coordinating atoms such as transition metals (TMs) or noble metals. All deposited atoms assume exactly the same specific sevenfold coordinated subsurface interstitial site while the surface topography remains nearly unchanged. Notably, 3 d TMs show a barrier-free incorporation. The observed surface modification by barrier-free subsorption helps to suppress aggregation in clusters. It allows a tuning of the electronic properties not only for the pure Bi (111 ) surface, but may also be observed for topological insulators formed by substrate-stabilized Bi bilayers.

  5. Barrier-free subsurface incorporation of 3d metal atoms into Bi(111) films

    DOE PAGESBeta

    Klein, C.; Vollmers, N. J.; Gerstmann, U.; Zahl, P.; Lukermann, D.; Jnawali, G.; Pfnur, H.; Sutter, P.; Tegenkamp, C.; Schmidt, W. G.; et al

    2015-05-27

    By combining scanning tunneling microscopy with density functional theory it is shown that the Bi(111) surface provides a well-defined incorporation site in the first bilayer that traps highly coordinating atoms such as transition metals (TMs) or noble metals. All deposited atoms assume exactly the same specific sevenfold coordinated subsurface interstitial site while the surface topography remains nearly unchanged. Notably, 3d TMs show a barrier-free incorporation. The observed surface modification by barrier-free subsorption helps to suppress aggregation in clusters. Thus, it allows a tuning of the electronic properties not only for the pure Bi(111) surface, but may also be observed formore » topological insulators formed by substrate-stabilized Bi bilayers.« less

  6. 3D display and image processing system for metal bellows welding

    NASA Astrophysics Data System (ADS)

    Park, Min-Chul; Son, Jung-Young

    2010-04-01

    Industrial welded metal Bellows is in shape of flexible pipeline. The most common form of bellows is as pairs of washer-shaped discs of thin sheet metal stamped from strip stock. Performing arc welding operation may cause dangerous accidents and bad smells. Furthermore, in the process of welding operation, workers have to observe the object directly through microscope adjusting the vertical and horizontal positions of welding rod tip and the bellows fixed on the jig, respectively. Welding looking through microscope makes workers feel tired. To improve working environment that workers sit in an uncomfortable position and productivity we introduced 3D display and image processing. Main purpose of the system is not only to maximize the efficiency of industrial productivity with accuracy but also to keep the safety standards with the full automation of work by distant remote controlling.

  7. A hybrid metalloarsenate 3D framework-1D interrupted metal oxide.

    PubMed

    Hughes, Robert W; Gerrard, Lee A; Price, Daniel J; Weller, Mark T

    2003-06-30

    Complex metal arsenates of the stoichiometry M(1)(-)(x)()M'(6)(OH)(3)(AsO(4)H(2)(x)()(/3))(3)(HAsO(4)), M = M' = Co, Ni, have been synthesized under hydrothermal conditions. The two compounds display a very similar structural topology to that of the mineral dumortierite, an uncommon complex oxyborosilicate of aluminum. The hybrid structures consist of well separated, vacancy interrupted chains of face sharing MO(6) octahedra, with short M.M distances near 2.5 A, embedded in a metalloarsenate 3D framework having the topology of the aluminosilicate cancrinite. The framework also contains a quadruply bridging hydroxide ion. Magnetic susceptibility measurements reveal a strong antiferromagnetic interaction and magnetic transition to low temperature spin canted phases below 51 K (Co) and 42 K (Ni). The material may be considered as a zeotype framework structure templated by an interrupted one-dimensional metal oxide. PMID:12817976

  8. Potentiometric and spectroscopic study of the interaction of 3d transition metal ions with inositol hexakisphosphate

    NASA Astrophysics Data System (ADS)

    Veiga, Nicolás; Macho, Israel; Gómez, Kerman; González, Gabriel; Kremer, Carlos; Torres, Julia

    2015-10-01

    Among myo-inositol phosphates, the most abundant in nature is the myo-inositol hexakisphosphate, InsP6. Although it is known to be vital to cell functioning, the biochemical research into its metabolism needs chemical and structural analysis of all the protonation, complexation and precipitation processes that it undergoes in the biological media. In view of its high negative charge at physiological level, our group has been leading a thorough research into the InsP6 chemical and structural behavior in the presence of the alkali and alkaline earth metal ions essential for life. The aim of this article is to extend these studies, dealing with the chemical and structural features of the InsP6 interaction with biologically relevant 3d transition metal ions (Fe(II), Fe(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)), in a non-interacting medium and under simulated physiological conditions. The metal-complex stability constants were determined by potentiometry, showing under ligand-excess conditions the formation of mononuclear species in different protonation states. Under metal ion excess, polymetallic species were detected for Fe(II), Fe(III), Zn(II) and Cu(II). Additionally, the 31P NMR and UV-vis spectroscopic studies provided interesting structural aspects of the strong metal ion-InsP6 interaction.

  9. Band structure and spin texture of Bi2Se3 3 d ferromagnetic metal interface

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Velev, Julian P.; Dang, Xiaoqian; Tsymbal, Evgeny Y.

    2016-07-01

    The spin-helical surface states in a three-dimensional topological insulator (TI), such as Bi2Se3 , are predicted to have superior efficiency in converting charge current into spin polarization. This property is said to be responsible for the giant spin-orbit torques observed in ferromagnetic metal/TI structures. In this work, using first-principles and model tight-binding calculations, we investigate the interface between the topological insulator Bi2Se3 and 3 d -transition ferromagnetic metals Ni and Co. We find that the difference in the work functions of the topological insulator and the ferromagnetic metals shift the topological surface states down about 0.5 eV below the Fermi energy where the hybridization of these surface states with the metal bands destroys their helical spin structure. The band alignment of Bi2Se3 and Ni (Co) places the Fermi energy far in the conduction band of bulk Bi2Se3 , where the spin of the carriers is aligned with the magnetization in the metal. Our results indicate that the topological surface states are unlikely to be responsible for the huge spin-orbit torque effect observed experimentally in these systems.

  10. Bi-Mn mixed metal organic oxide: A novel 3d-6p mixed metal coordination network

    NASA Astrophysics Data System (ADS)

    Shi, Fa-Nian; Rosa Silva, Ana; Bian, Liang

    2015-05-01

    A new terminology of metal organic oxide (MOO) was given a definition as a type of coordination polymers which possess the feature of inorganic connectivity between metals and the direct bonded atoms and show 1D, 2D or 3D inorganic sub-networks. One such compound was shown as an example. A 3d-6p (Mn-Bi. Named MOOMnBi) mixed metals coordination network has been synthesized via hydrothermal method. The new compound with the molecular formula of [MnBi2O(1,3,5-BTC)2]n (1,3,5-BTC stands for benzene-1,3,5-tricarboxylate) was characterized via single crystal X-ray diffraction technique that revealed a very interesting 3-dimensional (3D) framework with Bi4O2(COO)12 clusters which are further connected to Mn(COO)6 fragments into a 2D MOO. The topology study indicates an unprecedented topological type with the net point group of {413.62}{413.68}{416.65}{418.610}{422.614}{43} corresponding to 3,6,7,7,8,9-c hexa-nodal net. MOOMnBi shows catalytic activity in the synthesis of (E)-α,β-unsaturated ketones.

  11. Theory and modeling of light interactions with metallic nanostructures.

    SciTech Connect

    Montgomery, J. M.; Lee, T.-W.; Gray, S. K.; Louisiana State Univ.

    2008-08-13

    Metallic nanostructures such as systems containing metal nanoparticles or nanostructured metal films are intriguing systems of much current interest. Surface plasmons, i.e., special electronic excitations near the metallic surfaces, can then be excited in these systems. Surface plasmons can be intense and localized, and correctly describing their behavior in complex systems can require numerically rigorous modeling techniques. The finite-difference time-domain (FDTD) method is one such technique. This review discusses results obtained mostly with the FDTD method concerning (1) local surface plasmon excitations of metal nanoparticles, (2) surface plasmon polariton propagation on layered structures, and (3) periodic hole arrays in metal films.

  12. A systematic study of neutral and charged 3d-metal trioxides and tetraoxides

    NASA Astrophysics Data System (ADS)

    Pradhan, Kalpataru; Gutsev, Gennady L.; Weatherford, Charles A.; Jena, Purusottam

    2011-04-01

    Using density functional theory with generalized gradient approximation, we have performed a systematic study of the structure and properties of neutral and charged trioxides (MO3) and tetraoxides (MO4) of the 3d-metal atoms. The results of our calculations revealed a number of interesting features when moving along the 3d-metal series. (1) Geometrical configurations of the lowest total energy states of neutral and charged trioxides and tetraoxides are composed of oxo and/or peroxo groups, except for CuO3- and ZnO3- which possess a superoxo group, CuO4+ and ZnO4+ which possess two superoxo groups, and CuO3+, ZnO3+, and ZnO4- which possess an ozonide group. While peroxo groups are found in the early and late transition metals, all oxygen atoms bind chemically to the metal atom in the middle of the series. (2) Attachment or detachment of an electron to/from an oxide often leads to a change in the geometry. In some cases, two dissociatively attached oxygen atoms combine and form a peroxo group or a peroxo group transforms into a superoxo group and vice versa. (3) The adiabatic electron affinity of as many as two trioxides (VO3 and CoO3) and four tetraoxides (TiO4, CrO4, MnO4, and FeO4) are larger than the electron affinity of halogen atoms. All these oxides are hence superhalogens although only VO3 and MnO4 satisfy the general superhalogen formula.

  13. A systematic study of neutral and charged 3d-metal trioxides and tetraoxides.

    PubMed

    Pradhan, Kalpataru; Gutsev, Gennady L; Weatherford, Charles A; Jena, Purusottam

    2011-04-14

    Using density functional theory with generalized gradient approximation, we have performed a systematic study of the structure and properties of neutral and charged trioxides (MO(3)) and tetraoxides (MO(4)) of the 3d-metal atoms. The results of our calculations revealed a number of interesting features when moving along the 3d-metal series. (1) Geometrical configurations of the lowest total energy states of neutral and charged trioxides and tetraoxides are composed of oxo and∕or peroxo groups, except for CuO(3)(-) and ZnO(3)(-) which possess a superoxo group, CuO(4)(+) and ZnO(4)(+) which possess two superoxo groups, and CuO(3)(+), ZnO(3)(+), and ZnO(4)(-) which possess an ozonide group. While peroxo groups are found in the early and late transition metals, all oxygen atoms bind chemically to the metal atom in the middle of the series. (2) Attachment or detachment of an electron to∕from an oxide often leads to a change in the geometry. In some cases, two dissociatively attached oxygen atoms combine and form a peroxo group or a peroxo group transforms into a superoxo group and vice versa. (3) The adiabatic electron affinity of as many as two trioxides (VO(3) and CoO(3)) and four tetraoxides (TiO(4), CrO(4), MnO(4), and FeO(4)) are larger than the electron affinity of halogen atoms. All these oxides are hence superhalogens although only VO(3) and MnO(4) satisfy the general superhalogen formula. PMID:21495753

  14. Prevention of sulfur diffusion using MoS2-intercalated 3D-nanostructured graphite for high-performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Tiwari, Anand P.; Yoo, Heejoun; Lee, Jeongtaik; Kim, Doyoung; Park, Jong Hyeok; Lee, Hyoyoung

    2015-07-01

    We report new three-dimensional (3D)-nanostructured MoS2-carbonaceous materials in which MoS2 sheets are intercalated between the graphite layers that possess a multiply repeated graphite/MoS2/graphite structure which prevents the aggregation of MoS2 and diffusion of sulfur from carbonaceous materials, enhancing the cycling stability of Li-ion batteries. We developed an efficient and scalable process applicable to mass production for synthesizing non-aggregated MoS2-intercalated 3D hybrid-nanostructured graphite based on stress induced and microwave irradiation. X-ray diffraction, X-ray photospectroscopy, Raman spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy analyses demonstrated that the as-synthesized materials consisted of MoS2-intercalated 3D hybrid-nanostructured graphite platelets that had a multiply repeated graphite/MoS2/graphite structure. The obtained MoS2-graphite powder surpasses MoS2 as an anode material in terms of specific capacity, cyclic stability, and rate performances at high current densities for Li-ion batteries. The electrochemical impedance spectroscopy demonstrated that the graphite sheets not only reduced the contact resistance in the electrode but also facilitated electron transfer in the lithiation/delithiation processes. The superior electrochemical performances especially for the cycling stability of the Li-ion battery originate from prevention of the sulfur diffusion of the MoS2-intercalated 3D-nanostructured graphite.We report new three-dimensional (3D)-nanostructured MoS2-carbonaceous materials in which MoS2 sheets are intercalated between the graphite layers that possess a multiply repeated graphite/MoS2/graphite structure which prevents the aggregation of MoS2 and diffusion of sulfur from carbonaceous materials, enhancing the cycling stability of Li-ion batteries. We developed an efficient and scalable process applicable to mass production for synthesizing non

  15. Study of Photoionization Processes of 3d Transition Metal Compound CoCl2 Using Synchrotron Radiation

    SciTech Connect

    Goerguelueer, Oe.; Tutay, A.; Al-Hada, M.; Richter, T.; Zimmermann, P.; Martins, M.

    2007-04-23

    In this work, the photoionization processes of 3d transition metal compound CoCl2 have been investigated using monochromatized synchrotron radiation of the storage ring BESSY II and the atomic-molecular beam technique.

  16. Polymorphism Control in Nanostructured Metal Oxides

    NASA Astrophysics Data System (ADS)

    Sood, Shantanu

    Polymorphic phase transformations are common to all nanocrystalline binary metal oxides. The polymorphic nature of such metal oxides makes available a large number of phases with differing crystal structures, each stable under certain conditions of temperature, pressure, and/or particle size. These different crystal structures translate to unique physical and chemical properties for each structural class of polymorphs. Thus predicting when polymorphic phase transitions are likely to occur becomes important to the synthesis of stable functional materials with desired properties. Theoretical calculations using a heuristic approach have resulted in an accurate estimation of the critical particle size predicting metastable to stable phase transitions. This formula is applied to different case studies: for anatase to rutile titania; gamma-Alumina to alpha-Alumina; and tetragonal to monoclinic zirconia. The theoretical values calculated have been seen to be very close to the experimental results from the literature. Manifestation of the effect of phase transitions in nanostructured metal oxides was provided in the study of metastable to stable phase transitions in WO3. Nanowires of tungsten trioxide have been synthesized in-situ inside an electron microscope. Such structure of tungsten trioxide result due to a metastable to stable phase transformation, from the cubic to the monoclinic phase. The transformation is massive and complete. The structures formed are unique one-dimensional nanowires. Such a method can be scaled inside any equipment equipped with an electron gun, for example lithography systems either using STEM or E-beam lithography. Another study on nanowire formation in binary metal oxides involved the synthesis of stable orthorhombic MoO3 by means of blend electrospinning. Both a traditional single jet electrospinning set up and a novel high-throughput process to get high aspect ratio nanowires. The latter is a jet-controlled and flow controlled

  17. High-coverage stable structures of 3d transition metal intercalated bilayer graphene.

    PubMed

    Liao, Ji-Hai; Zhao, Yu-Jun; Tang, Jia-Jun; Yang, Xiao-Bao; Xu, Hu

    2016-06-01

    Alkali-metal intercalated graphite and graphene have been intensively studied for decades, where alkali-metal atoms are found to form ordered structures at the hollow sites of hexagonal carbon rings. Using first-principles calculations, we have predicted various stable structures of high-coverage 3d transition metal (TM) intercalated bilayer graphene (BLG) stabilized by the strain. Specifically, with reference to the bulk metal, Sc and Ti can form stable TM-intercalated BLG without strain, while the stabilization of Fe, Co, and Ni intercalated BLG requires the biaxial strain of over 7%. Under the biaxial strain ranging from 0% to 10%, there are four ordered sandwich structures for Sc with the coverage of 0.25, 0.571, 0.684, and 0.75, in which the Sc atoms are all distributed homogenously instead of locating at the hollow sites. According to the phase diagram, a homogenous configuration of C8Ti3C8 with the coverage of 0.75 and another inhomogeneous structure with the coverage of 0.692 were found. The electronic and magnetic properties as a function of strain were also analyzed to indicate that the strain was important for the stabilities of the high-coverage TM-intercalated BLG. PMID:27167998

  18. Experiments and parametric studies on 3D metallic auxetic metamaterials with tuneable mechanical properties

    NASA Astrophysics Data System (ADS)

    Ren, Xin; Shen, Jianhu; Ghaedizadeh, Arash; Tian, Hongqi; Xie, Yi Min

    2015-09-01

    Auxetic metamaterials are synthetic materials with microstructures engineered to achieve negative Poisson’s ratios. Auxetic metamaterials are of great interest because of their unusual properties and various potential applications. However, most of the previous research has been focused on auxetic behaviour of elastomers under elastic deformation. Inspired by our recent finding of the loss of auxetic behaviour in metallic auxetic metamaterials, a systematic experimental and numerical investigation has been carried out to explore the mechanism behind this phenomenon. Using an improved methodology of generating buckling-induced auxetic metamaterials, several samples of metallic auxetic metamaterials have been fabricated using a 3D printing technique. The experiments on those samples have revealed the special features of auxetic behaviour for metallic auxetic metamaterials and proved the effectiveness of our structural modification. Parametric studies have been performed through experimentally validated finite element models to explore the auxetic performance of the designed metallic metamaterials. It is found that the auxetic performance can be tuned by the geometry of microstructures, and the strength and stiffness can be tuned by the plasticity of the base material while maintaining the auxetic performance.

  19. Diffusion Monte Carlo for Accurate Dissociation Energies of 3d Transition Metal Containing Molecules.

    PubMed

    Doblhoff-Dier, Katharina; Meyer, Jörg; Hoggan, Philip E; Kroes, Geert-Jan; Wagner, Lucas K

    2016-06-14

    Transition metals and transition metal compounds are important to catalysis, photochemistry, and many superconducting systems. We study the performance of diffusion Monte Carlo (DMC) applied to transition metal containing dimers (TMCDs) using single-determinant Slater-Jastrow trial wavefunctions and investigate the possible influence of the locality and pseudopotential errors. We find that the locality approximation can introduce nonsystematic errors of up to several tens of kilocalories per mole in the absolute energy of Cu and CuH if Ar or Mg core pseudopotentials (PPs) are used for the 3d transition metal atoms. Even for energy differences such as binding energies, errors due to the locality approximation can be problematic if chemical accuracy is sought. The use of the Ne core PPs developed by Burkatzki et al. (J. Chem. Phys. 2008, 129, 164115), the use of linear energy minimization rather than unreweighted variance minimization for the optimization of the Jastrow function, and the use of large Jastrow parametrizations reduce the locality errors. In the second section of this article, we study the general performance of DMC for 3d TMCDs using a database of binding energies of 20 TMCDs, for which comparatively accurate experimental data is available. Comparing our DMC results to these data for our results that compare best with experiment, we find a mean unsigned error (MUE) of 4.5 kcal/mol. This compares well with the achievable accuracy in CCSDT(2)Q (MUE = 4.6 kcal/mol) and the best all-electron DFT results (MUE = 4.5 kcal/mol) for the same set of systems (Truhlar et al. J. Chem. Theory Comput. 2015, 11, 2036-2052). The mean errors in DMC depend less on the exchange-correlation functionals used to generate the trial wavefunction than the corresponding mean errors in the underlying DFT calculations. Furthermore, the QMC results obtained for each molecule individually vary less with the functionals used. These observations are relevant for systems such as

  20. Nanoionic switching in metal oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Ielmini, Daniele

    2013-03-01

    Ion migration in oxide nanostructures is a key process in information storage technologies, where the logic data are stored as nanoscale conductive filaments. Due to the inherently nanoscale size of the ionic switching location (few cubic nanometers), the local electric field and current density induce extremely high temperatures as a result of Joule heating. To develop and design advanced nanoionic materials and devices with improved performance and reliability, the ion migration phenomena in metal oxides must be carefully understood and modeled. This talk will address the modeling of ionic migration and the consequent switching in HfOx layers of RRAM devices. The model solves drift/diffusion equations for thermally-activated hopping of positive ion, such as oxygen vacancies (VO+)and metal cations (Hf+) , in presence of intense Joule heating and electric field. The impact of the ion distribution on the local conductivity is described physics-based models of defect-assisted electronic conduction in semiconductors. Microscopic parameters, such as the energy barrier for ion hopping, are directly inferred from the experimental switching kinetics at variable voltages. The simulation results picture the filament growth/depletion with time and account for the observed switching characteristics, such as the progressive opening of a depleted gap and the possibility of electrode-to-electrode migration of ions. Finally, new phenomena, such as switching variability at atomic-size filaments and stress-induced symmetric switching, will be discussed.

  1. 3D porous and ultralight carbon hybrid nanostructure fabricated from carbon foam covered by monolayer of nitrogen-doped carbon nanotubes for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    He, Shuijian; Hou, Haoqing; Chen, Wei

    2015-04-01

    3D porous and self-supported carbon hybrids are promising electrode materials for supercapacitor application attributed to their prominent properties such as binder-free electrode fabrication process, excellent electric conductivity and high power density etc. We present here a facile chemical vapor deposition method to fabricate a novel 3D flexible carbon hybrid nanostructure by growing a monolayer of nitrogen-doped carbon nanotubes on the skeleton of carbon foam (N-CNTs/CF) with Fe nanoparticle as catalyst. With such 3D porous, flexible and ultralight carbon nanostructure as binder-free electrode material, large surface area is available and fast ionic transport is facilitated. Moreover, the carbon-based network can provide excellent electronic conductivity. The electrochemical studies demonstrate that the supercapacitor constructed from the N-CNTs/CF hybrid exhibit high power density of 69.3 kW kg-1 and good stability with capacitance retention ration above 95% after cycled at 50 A g-1 for 5000 cycles. Therefore, the prepared porous N-CNTs/CF nanostructure is expected to be a type of excellent electrode material for electrical double layer capacitors.

  2. Triplet superconductivity in 3D Dirac semi-metal due to exchange interaction

    NASA Astrophysics Data System (ADS)

    Rosenstein, Baruch; Shapiro, B. Ya; Li, Dingping; Shapiro, I.

    2015-01-01

    Conventional phonon-electron interaction induces either triplet or one of two (degenerate) singlet pairing states in time reversal and inversion invariant 3D Dirac semi-metal. Investigation of the order parameters and energies of these states at zero temperature in a wide range of values of chemical potential μ, the effective electron-electron coupling constant λ and Debye energy TD demonstrates that when the exchange interaction is neglected the singlet always prevails, however, in significant portions of the (μ, λ, TD) parameter space the energy difference is very small. This means that interactions that are small, but discriminate between the spin singlet and the spin triplet, are important in order to determine the nature of the superconducting order there. The best candidate for such an interaction in the materials under consideration is the exchange (the Stoner term) characterized by constant λex. We show that at values of λex, much smaller than ones creating Stoner instability to ferromagnetism λex ˜ 1, the triplet pairing becomes energetically favored over the singlet ones. The 3D quantum critical point at μ = 0 is considered in detail. This can be realized experimentally in optically trapped cold atom systems.

  3. Triplet superconductivity in 3D Dirac semi-metal due to exchange interaction.

    PubMed

    Rosenstein, Baruch; Shapiro, B Ya; Li, Dingping; Shapiro, I

    2015-01-21

    Conventional phonon-electron interaction induces either triplet or one of two (degenerate) singlet pairing states in time reversal and inversion invariant 3D Dirac semi-metal. Investigation of the order parameters and energies of these states at zero temperature in a wide range of values of chemical potential μ, the effective electron-electron coupling constant λ and Debye energy TD demonstrates that when the exchange interaction is neglected the singlet always prevails, however, in significant portions of the (μ, λ, TD) parameter space the energy difference is very small. This means that interactions that are small, but discriminate between the spin singlet and the spin triplet, are important in order to determine the nature of the superconducting order there. The best candidate for such an interaction in the materials under consideration is the exchange (the Stoner term) characterized by constant λex. We show that at values of λex, much smaller than ones creating Stoner instability to ferromagnetism λex ∼ 1, the triplet pairing becomes energetically favored over the singlet ones. The 3D quantum critical point at μ = 0 is considered in detail. This can be realized experimentally in optically trapped cold atom systems. PMID:25501668

  4. 3D Imaging of Transition Metals in the Zebrafish Embryo by X-ray Fluorescence Microtomography

    PubMed Central

    Bourassa, Daisy; Gleber, Sophie-Charlotte; Vogt, Stefan; Yi, Hong; Will, Fabian; Richter, Heiko; Shin, Chong Hyun; Fahrni, Christoph J.

    2014-01-01

    Synchrotron X-ray fluorescence (SXRF) microtomography has emerged as a powerful technique for the 3D visualization of the elemental distribution in biological samples. The mechanical stability, both of the instrument and the specimen, is paramount when acquiring tomographic projection series. By combining the progressive lowering of temperature method (PLT) with femtosecond laser sectioning, we were able to embed, excise, and preserve a zebrafish embryo at 24 hours post fertilization in an X-ray compatible, transparent resin for tomographic elemental imaging. Based on a data set comprised of 60 projections, acquired with a step size of 2 μm during 100 hours of beam time, we reconstructed the 3D distribution of zinc, iron, and copper using the iterative maximum likelihood expectation maximization (MLEM) reconstruction algorithm. The volumetric elemental maps, which entail over 124 million individual voxels for each transition metal, revealed distinct elemental distributions that could be correlated with characteristic anatomical features at this stage of embryonic development. PMID:24992831

  5. Metal/Semiconductor hybrid nanostructures for plasmon-enhanced applications.

    PubMed

    Jiang, Ruibin; Li, Benxia; Fang, Caihong; Wang, Jianfang

    2014-08-20

    Hybrid nanostructures composed of semiconductor and plasmonic metal components are receiving extensive attention. They display extraordinary optical characteristics that are derived from the simultaneous existence and close conjunction of localized surface plasmon resonance and semiconduction, as well as the synergistic interactions between the two components. They have been widely studied for photocatalysis, plasmon-enhanced spectroscopy, biotechnology, and solar cells. In this review, the developments in the field of (plasmonic metal)/semiconductor hybrid nanostructures are comprehensively described. The preparation of the hybrid nanostructures is first presented according to the semiconductor type, as well as the nanostructure morphology. The plasmonic properties and the enabled applications of the hybrid nanostructures are then elucidated. Lastly, possible future research in this burgeoning field is discussed. PMID:24753398

  6. Theoretical study on the alloying behavior of γ-uranium metal: γ-uranium alloy with 3d transition metals

    NASA Astrophysics Data System (ADS)

    Kurihara, Masayoshi; Hirata, Masaru; Sekine, Rika; Onoe, Jun; Nakamatsu, Hirohide

    2004-03-01

    We have investigated the alloying behavior of γ-uranium with 3d transition metals (TMs) using the relativistic discrete-variational Dirac-Fock-Slater (DV-DFS) method. The d-orbital energy (Md) as an alloying parameter well reproduces the alloying behavior of γ-uranium metal with TMs: (1) in the case of a large Md value (Ti, V, Cr), the solubility of these TM elements in γ-uranium becomes large; (2) in the case of a middle Md value (Mn, Fe, Co), the tendency to form a uranium intermetallic compound with these elements becomes stronger; (3) in the case of a small Md value (Cu), the alloying element is insoluble in γ-uranium. The alloying behavior of γ-uranium with TMs is also discussed in terms of other parameters such as electronegativity and metallic radius.

  7. Computed Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2005-01-01

    In friction stir welding (FSW), a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and is carried with the macro-flow of the weld metal. By using CT images, a 3-dimensional (3D) image of the lead flow pattern can be reconstructed. CT imaging was found to be a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  8. Exchange Interaction Makes Superconductivity in 3D Dirac Semi-metal Triplet

    NASA Astrophysics Data System (ADS)

    Rosenstein, B.; Shapiro, B. Ya.; Li, Dingping; Shapiro, I.

    2015-04-01

    Conventional electron-phonon coupling induces either odd (triplet) or even (singlet) pairing states in a time reversal and inversion invariant Dirac semi-metal. In a certain range of the chemical potential and parameters characterizing the pairing attraction (effective electron-electron coupling constant and the Debye energy ) the energy of the singlet although always lower, prevails by a very slim margin over the triplet. This means that interactions that are small but discriminate between the spin singlet and the spin triplet determine the nature of the superconducting order there. It is shown that in materials close enough to the Dirac point ( ) a moderate exchange constant (below Stoner instability to ferromagnetism) stabilizes the odd pairing superconducting state. The 3D quantum critical point at of transition to the triplet superconductivity governs the physics of the superconductor.

  9. Density functional study of hydrazine N-N bond cleaving on 3d metal surfaces

    NASA Astrophysics Data System (ADS)

    Fathurrahman, Fadjar; Kasai, Hideaki

    2015-11-01

    Theoretical calculations based on dispersion-corrected density functional theory (DFT-D2) has been performed to investigate hydrazine adsorption and N-N bond cleaving on closed packed surfaces of 3d metals: Fe(110), Co(0001), Ni(111), Cu(111), and Zn(0001). The activation energies of N-N bond cleaving of hydrazine on each surface are estimated using climbing-image nudged elastic band (CINEB) method. The results showed that the activation energies for this process have increasing trend from Fe(110) to Zn(0001). By examining the electronic structure of the adsorbed hydrazine, it is found that this trend is related to occupation of derived 6σ* orbitals. It is also found that approximate linear relationship between reaction energy and activation energy (the Brønsted-Evans-Polanyi (BEP) relationship) holds for those surfaces.

  10. 3d Transition Metal Adsorption Induced the valley-polarized Anomalous Hall Effect in Germanene

    PubMed Central

    Zhou, P.; Sun, L. Z.

    2016-01-01

    Based on DFT + U and Berry curvature calculations, we study the electronic structures and topological properties of 3d transition metal (TM) atom (from Ti to Co) adsorbed germanene (TM-germanene). We find that valley-polarized anomalous Hall effect (VAHE) can be realized in germanene by adsorbing Cr, Mn, or Co atoms on its surface. A finite valley Hall voltage can be easily detected in their nanoribbon, which is important for valleytronics devices. Moreover, different valley-polarized current and even reversible valley Hall voltage can be archived by shifting the Fermi energy of the systems. Such versatile features of the systems show potential in next generation electronics devices. PMID:27312176

  11. Reaching the magnetic anisotropy limit of a 3d metal atom.

    PubMed

    Rau, Ileana G; Baumann, Susanne; Rusponi, Stefano; Donati, Fabio; Stepanow, Sebastian; Gragnaniello, Luca; Dreiser, Jan; Piamonteze, Cinthia; Nolting, Frithjof; Gangopadhyay, Shruba; Albertini, Oliver R; Macfarlane, Roger M; Lutz, Christopher P; Jones, Barbara A; Gambardella, Pietro; Heinrich, Andreas J; Brune, Harald

    2014-05-30

    Designing systems with large magnetic anisotropy is critical to realize nanoscopic magnets. Thus far, the magnetic anisotropy energy per atom in single-molecule magnets and ferromagnetic films remains typically one to two orders of magnitude below the theoretical limit imposed by the atomic spin-orbit interaction. We realized the maximum magnetic anisotropy for a 3d transition metal atom by coordinating a single Co atom to the O site of an MgO(100) surface. Scanning tunneling spectroscopy reveals a record-high zero-field splitting of 58 millielectron volts as well as slow relaxation of the Co atom's magnetization. This striking behavior originates from the dominating axial ligand field at the O adsorption site, which leads to out-of-plane uniaxial anisotropy while preserving the gas-phase orbital moment of Co, as observed with x-ray magnetic circular dichroism. PMID:24812206

  12. Magnetic ordering in digital alloys of group-IV semiconductors with 3d-transition metals

    SciTech Connect

    Otrokov, M. M.; Tugushev, V. V.; Ernst, A.; Ostanin, S. A.; Kuznetsov, V. M.; Chulkov, E. V.

    2011-04-15

    The ab initio investigation of the magnetic ordering in digital alloys consisting of monolayers of 3d-transition metals Ti, V, Cr, Mn, Fe, Co, and Ni introduced into the Si, Ge, and Si{sub 0.5}Ge{sub 0.5} semiconductor hosts is reported. The calculations of the parameters of the exchange interactions and total-energy calculations indicate that the ferromagnetic order appears only in the manganese monolayers, whereas the antiferromagnetic order is more probable in V, Cr, and Fe monolayers, and Ti, Co, and Ni monolayers are nonmagnetic. The stability of the ferromagnetic phase in digital alloys containing manganese monolayers has been analyzed using the calculations of magnon spectra.

  13. Dirac cones in artificial structures of 3d transitional-metals doped Mg-Al spinels

    NASA Astrophysics Data System (ADS)

    Lu, Yuan; Feng, Min; Shao, Bin; Zuo, Xu

    2014-05-01

    Motivated by recent theoretical predications for Dirac cone in two-dimensional (2D) triangular lattice [H. Ishizuka, Phys. Rev. Lett. 109, 237207 (2012)], first-principles studies are performed to predict Dirac cones in artificial structures of 3d transitional-metals (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped Mg-Al spinels. In investigated artificial structures, TM dopants substitute specific positions of the B sub-lattice in Mg-Al spinel, and form a quasi-2D triangular lattice in the a-b plane. Calculated results illustrate the existence of the spin-polarized Dirac cones formed in d-wave bands at (around) the K-point in the momentum space. The study provides a promising route for engineering Dirac physics in condensed matters.

  14. Dirac cones in artificial structures of 3d transitional-metals doped Mg-Al spinels

    SciTech Connect

    Lu, Yuan; Zuo, Xu; Feng, Min; Shao, Bin

    2014-05-07

    Motivated by recent theoretical predications for Dirac cone in two-dimensional (2D) triangular lattice [H. Ishizuka, Phys. Rev. Lett. 109, 237207 (2012)], first-principles studies are performed to predict Dirac cones in artificial structures of 3d transitional-metals (TM = Ti, V, Cr, Mn, Fe, Co, Ni, and Cu) doped Mg-Al spinels. In investigated artificial structures, TM dopants substitute specific positions of the B sub-lattice in Mg-Al spinel, and form a quasi-2D triangular lattice in the a-b plane. Calculated results illustrate the existence of the spin-polarized Dirac cones formed in d-wave bands at (around) the K-point in the momentum space. The study provides a promising route for engineering Dirac physics in condensed matters.

  15. 3d Transition Metal Adsorption Induced the valley-polarized Anomalous Hall Effect in Germanene.

    PubMed

    Zhou, P; Sun, L Z

    2016-01-01

    Based on DFT + U and Berry curvature calculations, we study the electronic structures and topological properties of 3d transition metal (TM) atom (from Ti to Co) adsorbed germanene (TM-germanene). We find that valley-polarized anomalous Hall effect (VAHE) can be realized in germanene by adsorbing Cr, Mn, or Co atoms on its surface. A finite valley Hall voltage can be easily detected in their nanoribbon, which is important for valleytronics devices. Moreover, different valley-polarized current and even reversible valley Hall voltage can be archived by shifting the Fermi energy of the systems. Such versatile features of the systems show potential in next generation electronics devices. PMID:27312176

  16. Accommodating lithium into 3D current collectors with a submicron skeleton towards long-life lithium metal anodes

    PubMed Central

    Yang, Chun-Peng; Yin, Ya-Xia; Zhang, Shuai-Feng; Li, Nian-Wu; Guo, Yu-Guo

    2015-01-01

    Lithium metal is one of the most attractive anode materials for electrochemical energy storage. However, the growth of Li dendrites during electrochemical deposition, which leads to a low Coulombic efficiency and safety concerns, has long hindered the application of rechargeable Li-metal batteries. Here we show that a 3D current collector with a submicron skeleton and high electroactive surface area can significantly improve the electrochemical deposition behaviour of Li. Li anode is accommodated in the 3D structure without uncontrollable Li dendrites. With the growth of Li dendrites being effectively suppressed, the Li anode in the 3D current collector can run for 600 h without short circuit and exhibits low voltage hysteresis. The exceptional electrochemical performance of the Li-metal anode in the 3D current collector highlights the importance of rational design of current collectors and reveals a new avenue for developing Li anodes with a long lifespan. PMID:26299379

  17. Accommodating lithium into 3D current collectors with a submicron skeleton towards long-life lithium metal anodes.

    PubMed

    Yang, Chun-Peng; Yin, Ya-Xia; Zhang, Shuai-Feng; Li, Nian-Wu; Guo, Yu-Guo

    2015-01-01

    Lithium metal is one of the most attractive anode materials for electrochemical energy storage. However, the growth of Li dendrites during electrochemical deposition, which leads to a low Coulombic efficiency and safety concerns, has long hindered the application of rechargeable Li-metal batteries. Here we show that a 3D current collector with a submicron skeleton and high electroactive surface area can significantly improve the electrochemical deposition behaviour of Li. Li anode is accommodated in the 3D structure without uncontrollable Li dendrites. With the growth of Li dendrites being effectively suppressed, the Li anode in the 3D current collector can run for 600 h without short circuit and exhibits low voltage hysteresis. The exceptional electrochemical performance of the Li-metal anode in the 3D current collector highlights the importance of rational design of current collectors and reveals a new avenue for developing Li anodes with a long lifespan. PMID:26299379

  18. Metallic glass nanostructures of tunable shape and composition.

    PubMed

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J; Schroers, Jan

    2015-01-01

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top-down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties. PMID:25901951

  19. Plasmonic properties of metal-vanadium dioxide nanostructures

    NASA Astrophysics Data System (ADS)

    Suh, Jae Yong

    This research is concerned with the fabrication of vanadium dioxide in the form of thin films and nanoparticles, and its effect on optical functionality when joined with two kinds of metallic nanostructures. As for the underlying physical phenomena, the metal-insulator phase transition in VO2 and the optical properties are studied. For the modulation of extraordinary transmission, metal-VO2 double-layer subwavelength aperture arrays were fabricated. For the modulation of the localized surface plasmon resonance of noble metal nanoparticles, gold nanoparticle arrays enveloped in a VO 2 thin film were created. These two-dimensional metal nanostructures incorporating a VO2 thin film exhibit a reverse hysteretic behavior and a plasmon resonance shift, respectively. Experimental measurements and simulations confirm that the complex dielectric functions of VO2 play an essential role in controlling the plasmonic properties of metal nanostructures.

  20. Metallic glass nanostructures of tunable shape and composition

    PubMed Central

    Liu, Yanhui; Liu, Jingbei; Sohn, Sungwoo; Li, Yanglin; Cha, Judy J.; Schroers, Jan

    2015-01-01

    Metals of hybrid nano-/microstructures are of broad technological and fundamental interests. Manipulation of shape and composition on the nanoscale, however, is challenging, especially for multicomponent alloys such as metallic glasses. Although top–down approaches have demonstrated nanomoulding, they are limited to very few alloy systems. Here we report a facile method to synthesize metallic glass nanoarchitectures that can be applied to a broad range of glass-forming alloys. This strategy, using multitarget carousel oblique angle deposition, offers the opportunity to achieve control over size, shape and composition of complex alloys at the nanoscale. As a consequence, nanostructures of programmable three-dimensional shapes and tunable compositions are realized on wafer scale for metallic glasses including the marginal glass formers. Realizing nanostructures in a wide compositional range allows chemistry optimization for technological usage of metallic glass nanostructures, and also enables the fundamental study on size, composition and fabrication dependences of metallic glass properties. PMID:25901951

  1. Geometrically induced surface polaritons in planar nanostructured metallic cavities

    SciTech Connect

    Davids, P. S.; Intravia, F; Dalvit, Diego A.

    2014-01-14

    We examine the modal structure and dispersion of periodically nanostructured planar metallic cavities within the scattering matrix formulation. By nanostructuring a metallic grating in a planar cavity, artificial surface excitations or spoof plasmon modes are induced with dispersion determined by the periodicity and geometric characteristics of the grating. These spoof surface plasmon modes are shown to give rise to new cavity polaritonic modes at short mirror separations that modify the density of modes in nanostructured cavities. The increased modal density of states form cavity polarirons have a large impact on the fluctuation induced electromagnetic forces and enhanced hear transfer at short separations.

  2. Contributions for the next generation of 3D metal printing machines

    NASA Astrophysics Data System (ADS)

    Pereira, M.; Thombansen, U.

    2015-03-01

    The 3D metal printing processes are key technologies for the new industry manufacturing requirements, as small lot production associated with high design complexity and high flexibility are needed towards personalization and customization. The main challenges for these processes are associated to increasing printing volumes, maintaining the relative accuracy level and reducing the global manufacturing time. Through a review on current technologies and solutions proposed by global patents new design solutions for 3D metal printing machines can be suggested. This paper picks up current technologies and trends in SLM and suggests some design approaches to overcome these challenges. As the SLM process is based on laser scanning, an increase in printing volume requires moving the scanner over the work surface by motion systems if printing accuracy has to be kept constant. This approach however does not contribute to a reduction in manufacturing time, as only one laser source will be responsible for building the entire work piece. With given technology limits in galvo based laser scanning systems, the most obvious solution consists in using multiple beam delivery systems in series, in parallel or both. Another concern is related to the weight of large work pieces. A new powder recoater can control the layer thickness and uniformity and eliminate or diminish fumes. To improve global accuracy, the use of a pair of high frequency piezoelectric actuators can help in positioning the laser beam. The implementation of such suggestions can contribute to SLM productivity. To do this, several research activities need to be accomplished in areas related to design, control, software and process fundamentals.

  3. Aerosol based direct-write micro-additive fabrication method for sub-mm 3D metal-dielectric structures

    NASA Astrophysics Data System (ADS)

    Rahman, Taibur; Renaud, Luke; Heo, Deuk; Renn, Michael; Panat, Rahul

    2015-10-01

    The fabrication of 3D metal-dielectric structures at sub-mm length scale is highly important in order to realize low-loss passives and GHz wavelength antennas with applications in wearable and Internet-of-Things (IoT) devices. The inherent 2D nature of lithographic processes severely limits the available manufacturing routes to fabricate 3D structures. Further, the lithographic processes are subtractive and require the use of environmentally harmful chemicals. In this letter, we demonstrate an additive manufacturing method to fabricate 3D metal-dielectric structures at sub-mm length scale. A UV curable dielectric is dispensed from an Aerosol Jet system at 10-100 µm length scale and instantaneously cured to build complex 3D shapes at a length scale  <1 mm. A metal nanoparticle ink is then dispensed over the 3D dielectric using a combination of jetting action and tilted dispense head, also using the Aerosol Jet technique and at a length scale 10-100 µm, followed by the nanoparticle sintering. Simulation studies are carried out to demonstrate the feasibility of using such structures as mm-wave antennas. The manufacturing method described in this letter opens up the possibility of fabricating an entirely new class of custom-shaped 3D structures at a sub-mm length scale with potential applications in 3D antennas and passives.

  4. Recipe for High Moment Materials with Rare-earth and 3d Transition Metal Composites

    PubMed Central

    Autieri, Carmine; Kumar, P. Anil; Walecki, Dirk; Webers, Samira; Gubbins, Mark A.; Wende, Heiko; Sanyal, Biplab

    2016-01-01

    Materials with high volume magnetization are perpetually needed for the generation of sufficiently large magnetic fields by writer pole of magnetic hard disks, especially for achieving increased areal density in storage media. In search of suitable materials combinations for this purpose, we have employed density functional theory to predict the magnetic coupling between iron and gadolinium layers separated by one to several monolayers of 3d transition metals (Sc-Zn). We demonstrate that it is possible to find ferromagnetic coupling for many of them and in particular for the early transition metals giving rise to high moment. Cr and Mn are the only elements able to produce a significant ferromagnetic coupling for thicker spacer layers. We also present experimental results on two trilayer systems Fe/Sc/Gd and Fe/Mn/Gd. From the experiments, we confirm a ferromagnetic coupling between Fe and Gd across a 3 monolayers Sc spacer or a Mn spacer thicker than 1 monolayer. In addition, we observe a peculiar dependence of Fe/Gd magnetic coupling on the Mn spacer thickness. PMID:27381456

  5. Carbon deposition from aromatic solvents onto active intact 3d metal surface at ambient conditions.

    PubMed

    Safronov, A P; Kurlyandskaya, G V; Chlenova, A A; Kuznetsov, M V; Bazhin, D N; Beketov, I V; Sanchez-Ilarduya, M B; Martinez-Amesti, A

    2014-03-25

    The process of carbon deposition onto 3d metal surface immersed in aromatic solvents (benzene, toluene, xylene) at ambient conditions was studied for as-prepared magnetic nanoparticles (MNPs) and Fe-based films by thermal analysis, mass spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, electron microscopy, and energy-dispersive X-ray spectroscopy. The mechanism of the deposition at the interface is likely the heterogeneous Scholl oxidation of the aromatic hydrocarbons, which is the cationic polymerization of the aryl rings. It results in the formation of polycyclic aromatic hydrocarbons (PAH) chemically bonded to the surface of a MNP or thin metallic film. The benzene rings in the polycyclic deposit do not maintain planar aligned structures and do not provide delocalization of the π-electrons in the zone structure. Contrary to the dense graphite layers, the polycyclic layers, although chemically bonded, are not attached tightly to the surface. Such "hairlike" structure of the carboneous deposit might be especially favorable for the applications that imply the enhanced interaction at the surfaces incorporated in the functional matrices (polymeric composites or biosensors). The aromatic chemical nature of the deposit provides strong interaction with most polymers, while its loose structure favors conformational mobility of macromolecular chains at the interface. PMID:24593324

  6. Resonant x-ray scattering in 3d-transition-metal oxides: Anisotropy and charge orderings

    NASA Astrophysics Data System (ADS)

    Subías, G.; García, J.; Blasco, J.; Herrero-Martín, J.; Sánchez, M. C.

    2009-11-01

    The structural, magnetic and electronic properties of transition metal oxides reflect in atomic charge, spin and orbital degrees of freedom. Resonant x-ray scattering (RXS) allows us to perform an accurate investigation of all these electronic degrees. RXS combines high-Q resolution x-ray diffraction with the properties of the resonance providing information similar to that obtained by atomic spectroscopy (element selectivity and a large enhancement of scattering amplitude for this particular element and sensitivity to the symmetry of the electronic levels through the multipole electric transitions). Since electronic states are coupled to the local symmetry, RXS reveals the occurrence of symmetry breaking effects such as lattice distortions, onset of electronic orbital ordering or ordering of electronic charge distributions. We shall discuss the strength of RXS at the K absorption edge of 3d transition-metal oxides by describing various applications in the observation of local anisotropy and charge disproportionation. Examples of these resonant effects are (I) charge ordering transitions in manganites, Fe3O4 and ferrites and (II) forbidden reflections and anisotropy in Mn3+ perovskites, spinel ferrites and cobalt oxides. In all the studied cases, the electronic (charge and/or anisotropy) orderings are determined by the structural distortions.

  7. Recipe for High Moment Materials with Rare-earth and 3d Transition Metal Composites

    NASA Astrophysics Data System (ADS)

    Autieri, Carmine; Kumar, P. Anil; Walecki, Dirk; Webers, Samira; Gubbins, Mark A.; Wende, Heiko; Sanyal, Biplab

    2016-07-01

    Materials with high volume magnetization are perpetually needed for the generation of sufficiently large magnetic fields by writer pole of magnetic hard disks, especially for achieving increased areal density in storage media. In search of suitable materials combinations for this purpose, we have employed density functional theory to predict the magnetic coupling between iron and gadolinium layers separated by one to several monolayers of 3d transition metals (Sc-Zn). We demonstrate that it is possible to find ferromagnetic coupling for many of them and in particular for the early transition metals giving rise to high moment. Cr and Mn are the only elements able to produce a significant ferromagnetic coupling for thicker spacer layers. We also present experimental results on two trilayer systems Fe/Sc/Gd and Fe/Mn/Gd. From the experiments, we confirm a ferromagnetic coupling between Fe and Gd across a 3 monolayers Sc spacer or a Mn spacer thicker than 1 monolayer. In addition, we observe a peculiar dependence of Fe/Gd magnetic coupling on the Mn spacer thickness.

  8. Recipe for High Moment Materials with Rare-earth and 3d Transition Metal Composites.

    PubMed

    Autieri, Carmine; Kumar, P Anil; Walecki, Dirk; Webers, Samira; Gubbins, Mark A; Wende, Heiko; Sanyal, Biplab

    2016-01-01

    Materials with high volume magnetization are perpetually needed for the generation of sufficiently large magnetic fields by writer pole of magnetic hard disks, especially for achieving increased areal density in storage media. In search of suitable materials combinations for this purpose, we have employed density functional theory to predict the magnetic coupling between iron and gadolinium layers separated by one to several monolayers of 3d transition metals (Sc-Zn). We demonstrate that it is possible to find ferromagnetic coupling for many of them and in particular for the early transition metals giving rise to high moment. Cr and Mn are the only elements able to produce a significant ferromagnetic coupling for thicker spacer layers. We also present experimental results on two trilayer systems Fe/Sc/Gd and Fe/Mn/Gd. From the experiments, we confirm a ferromagnetic coupling between Fe and Gd across a 3 monolayers Sc spacer or a Mn spacer thicker than 1 monolayer. In addition, we observe a peculiar dependence of Fe/Gd magnetic coupling on the Mn spacer thickness. PMID:27381456

  9. Heterobimetallic coordination polymers involving 3d metal complexes and heavier transition metals cyanometallates

    SciTech Connect

    Peresypkina, Eugenia V.; Samsonenko, Denis G.; Vostrikova, Kira E.

    2015-04-15

    The results of the first steps in the design of coordination polymers based on penta- and heptacyanometallates of heavier d transitions metals are presented. The 2D structure of the coordination polymers: [(Mn(acacen)){sub 2}Ru(NO)(CN){sub 5}]{sub n} and two complexes composed of different cyanorhenates, [Ni(cyclam)]{sub 2}[ReO(OH)(CN){sub 4}](ClO{sub 4}){sub 2}(H{sub 2}O){sub 1.25} and [Cu(cyclam)]{sub 2}[Re(CN){sub 7}](H{sub 2}O){sub 12}, was confirmed by single crystal XRD study, the rhenium oxidation state having been proved by the magnetic measurements. An amorphism of [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2} (M=Ni, Cu) polymers does not allow to define strictly their dimensionality and to model anisotropic magnetic behavior of the compounds. However, with high probability a honey-comb like layer structure could be expected for [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2} complexes, studied in this work, because such an arrangement is the most common among the bimetallic assemblies of hexa- and octacyanometallates with a ratio [M(cyclam)]/[M(CN){sub n}]=3/2. For the first time was prepared and fully characterized a precursor (n-Bu{sub 4}N){sub 2}[Ru(NO)(CN){sub 5}], soluble in organic media. - Graphical abstract: The very first results in the design of 2D coordination polymers based on penta- and heptacyanometallates of 4d and5d transitions metals are presented. - Highlights: • Design of coordination polymers based on penta- and heptacyanometallates. • New Ru and Re cyanide based heterobimetallic coordination complexes. • Hydrolysis and ox/red processes involving [Re(CN){sub 7}]{sup 3+} during crystallization. • High magnetic anisotropy of [M(cyclam)]{sub 3}[Re(CN){sub 7}]{sub 2}(H{sub 2}O){sub n}, M=Cu, Ni, complexes.

  10. Heterobimetallic coordination polymers involving 3d metal complexes and heavier transition metals cyanometallates

    NASA Astrophysics Data System (ADS)

    Peresypkina, Eugenia V.; Samsonenko, Denis G.; Vostrikova, Kira E.

    2015-04-01

    The results of the first steps in the design of coordination polymers based on penta- and heptacyanometallates of heavier d transitions metals are presented. The 2D structure of the coordination polymers: [{Mn(acacen)}2Ru(NO)(CN)5]n and two complexes composed of different cyanorhenates, [Ni(cyclam)]2[ReO(OH)(CN)4](ClO4)2(H2O)1.25 and [Cu(cyclam)]2[Re(CN)7](H2O)12, was confirmed by single crystal XRD study, the rhenium oxidation state having been proved by the magnetic measurements. An amorphism of [M(cyclam)]3[Re(CN)7]2 (M=Ni, Cu) polymers does not allow to define strictly their dimensionality and to model anisotropic magnetic behavior of the compounds. However, with high probability a honey-comb like layer structure could be expected for [M(cyclam)]3[Re(CN)7]2 complexes, studied in this work, because such an arrangement is the most common among the bimetallic assemblies of hexa- and octacyanometallates with a ratio [M(cyclam)]/[M(CN)n]=3/2. For the first time was prepared and fully characterized a precursor (n-Bu4N)2[Ru(NO)(CN)5], soluble in organic media.

  11. Large-scale dynamic assembly of metal nanostructures in plasmofluidic field.

    PubMed

    Patra, Partha Pratim; Chikkaraddy, Rohit; Thampi, Sreeja; Tripathi, Ravi P N; Kumar, G V Pavan

    2016-04-12

    We discuss two aspects of the plasmofluidic assembly of plasmonic nanostructures at the metal-fluid interface. First, we experimentally show how three and four spot evanescent-wave excitation can lead to unconventional assembly of plasmonic nanoparticles at the metal-fluid interface. We observed that the pattern of assembly was mainly governed by the plasmon interference pattern at the metal-fluid interface, and further led to interesting dynamic effects within the assembly. The interference patterns were corroborated by 3D finite-difference time-domain simulations. Secondly, we show how anisotropic geometry, such as Ag nanowires, can be assembled and aligned in unstructured and structured plasmofluidic fields. We found that by structuring the metal-film, Ag nanowires can be aligned at the metal-fluid interface with a single evanescent-wave excitation, thus highlighting the prospect of assembling plasmonic circuits in a fluid. An interesting aspect of our method is that we obtain the assembly at locations away from the excitation points, thus leading to remote assembly of nanostructures. The results discussed herein may have implications in realizing a platform for reconfigurable plasmonic metamaterials, and a test-bed to understand the effect of plasmon interference on assembly of nanostructures in fluids. PMID:26765282

  12. Growth of metal and semiconductor nanostructures using localized photocatalysts

    SciTech Connect

    Shelnutt, John A; Wang, Zhongchun; Medforth, Craig J

    2006-03-08

    Our overall goal has been to understand and develop a light-driven approach to the controlled growth of novel metal and semiconductor nanostructures and nanomaterials. In this photochemical process, bio-inspired porphyrin-based photocatalysts reduce metal salts in aqueous solutions at ambient temperatures when exposed to visible light, providing metal nucleation and growth centers. The photocatalyst molecules are pre-positioned at the nanoscale to control the location of the deposition of metal and therefore the morphology of the nanostructures that are grown. Self-assembly, chemical confinement, and molecular templating are some of the methods we are using for nanoscale positioning of the photocatalyst molecules. When exposed to light, each photocatalyst molecule repeatedly reduces metal ions from solution, leading to deposition near the photocatalyst and ultimately the synthesis of new metallic nanostructures and nanostructured materials. Studies of the photocatalytic growth process and the resulting nanostructures address a number of fundamental biological, chemical, and environmental issues and draw on the combined nanoscience characterization and multi-scale simulation capabilities of the new DOE Center for Integrated Nanotechnologies at Sandia National Laboratories and the University of Georgia. Our main goals are to elucidate the processes involved in the photocatalytic growth of metal nanomaterials and provide the scientific basis for controlled nanosynthesis. The nanomaterials resulting from these studies have applications in nanoelectronics, photonics, sensors, catalysis, and micromechanical systems. Our specific goals for the past three years have been to understand the role of photocatalysis in the synthesis of dendritic metal (Pt, Pd, Au) nanostructures grown from aqueous surfactant solutions under ambient conditions and the synthesis of photocatalytic porphyrin nanostructures (e.g., nanotubes) as templates for fabrication of photo-active metal

  13. Nanostructured transition metal oxides useful for water oxidation catalysis

    DOEpatents

    Frei, Heinz M; Jiao, Feng

    2013-12-24

    The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

  14. 3D-nanostructured Au electrodes for the event-specific detection of MON810 transgenic maize.

    PubMed

    Barroso, M Fátima; Freitas, Maria; Oliveira, M Beatriz P P; de-los-Santos-Álvarez, Noemí; Lobo-Castañón, María Jesús; Delerue-Matos, Cristina

    2015-03-01

    In the present work, the development of a genosensor for the event-specific detection of MON810 transgenic maize is proposed. Taking advantage of nanostructuration, a cost-effective three dimensional electrode was fabricated and a ternary monolayer containing a dithiol, a monothiol and the thiolated capture probe was optimized to minimize the unspecific signals. A sandwich format assay was selected as a way of precluding inefficient hybridization associated with stable secondary target structures. A comparison between the analytical performance of the Au nanostructured electrodes and commercially available screen-printed electrodes highlighted the superior performance of the nanostructured ones. Finally, the genosensor was effectively applied to detect the transgenic sequence in real samples, showing its potential for future quantitative analysis. PMID:25618653

  15. Electronic and magnetic structure of 3d-transition-metal point defects in silicon calculated from first principles

    NASA Astrophysics Data System (ADS)

    Beeler, F.; Andersen, O. K.; Scheffler, M.

    1990-01-01

    We describe spin-unrestricted self-consistent linear muffin-tin-orbital (LMTO) Green-function calculations for Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu transition-metal impurities in crystalline silicon. Both defect sites of tetrahedral symmetry are considered. All possible charge states with their spin multiplicities, magnetization densities, and energy levels are discussed and explained with a simple physical picture. The early transition-metal interstitial and late transition-metal substitutional 3d ions are found to have low spin. This is in conflict with the generally accepted crystal-field model of Ludwig and Woodbury, but not with available experimental data. For the interstitial 3d ions, the calculated deep donor and acceptor levels reproduce all experimentally observed transitions. For substitutional 3d ions, a large number of predictions is offered to be tested by future experimental studies.

  16. Red, green and blue reflections enabled in an optically tunable self-organized 3D cubic nanostructured thin film.

    PubMed

    Lin, Tsung-Hsien; Li, Yannian; Wang, Chun-Ta; Jau, Hung-Chang; Chen, Chun-Wei; Li, Cheng-Chung; Bisoyi, Hari Krishna; Bunning, Timothy J; Li, Quan

    2013-09-25

    A new light-driven chiral molecular switch doped in a stable blue phase (BP) liquid crystal allows wide optical tunability of three-dimensional cubic nanostructures with a selective reflection wavelength that is reversibly tuned through the visible region. Moreover, unprecedented reversible light-directed red, green, and blue reflections of the self-organized three-dimensional cubic nanostructure in a single film are demonstrated for the first time. Additionally, unusual isothermal photo-stimulated less ordered BP II to more ordered BP I phase transition was observed in the system. PMID:23913627

  17. Understanding the biological responses of nanostructured metals and surfaces

    NASA Astrophysics Data System (ADS)

    Lowe, Terry C.; Reiss, Rebecca A.

    2014-08-01

    Metals produced by Severe Plastic Deformation (SPD) offer distinct advantages for medical applications such as orthopedic devices, in part because of their nanostructured surfaces. We examine the current theoretical foundations and state of knowledge for nanostructured biomaterials surface optimization within the contexts that apply to bulk nanostructured metals, differentiating how their microstructures impact osteogenesis, in particular, for Ultrafine Grained (UFG) titanium. Then we identify key gaps in the research to date, pointing out areas which merit additional focus within the scientific community. For example, we highlight the potential of next-generation DNA sequencing techniques (NGS) to reveal gene and non-coding RNA (ncRNA) expression changes induced by nanostructured metals. While our understanding of bio-nano interactions is in its infancy, nanostructured metals are already being marketed or developed for medical devices such as dental implants, spinal devices, and coronary stents. Our ability to characterize and optimize the biological response of cells to SPD metals will have synergistic effects on advances in materials, biological, and medical science.

  18. 3d-Metal Doped into LiMn2O4 Thin Films

    SciTech Connect

    Bates, J.B.; Ueda, A.; Zuhr, R.A.

    1998-11-01

    3d-metal (Me) doped LiMn{sub 2}O{sub 4} thin films were deposited by rf magnetron sputtering of Li[Mn{sub 1.9}Me{sub 0.1}]O{sub 4} targets in Ar + N{sub 2} and Ar + O{sub 2} gas mixtures and annealed at 750{degrees}C in O{sub 2} for 1 h. From XRD measurements, the structure of the Me-doped thin film was dependent upon the element and the deposition conditions. The doping level of Me/Mn of cubic phase was less than 0.1 by EDX measurements. The Ti-LiMn{sub 2}O{sub 4} films exhibited a capacity close to theoretical for stoichiometric LiMn{sub 2}O{sub 4}. This improvement at 4 V comes at the expense of the capacity at 5 V. Cells with Ti-doped films exhibited the same low capacity fade as those with undoped LiMn{sub 2}O{sub 4} cathodes. Similar electrochemical changes were observed with the Cr- and Zn-LiMn{sub 2}O{sub 4} films. The discharge capacities above 4.5 V for the Ni-doped films were about equal to those below 4.5 V, and the thin-film cells could be cycled reversibility between 3.5 and 5.3 V.

  19. Discovery of a 3d-transition-metal-based ferromagnetic Kondo lattice system

    NASA Astrophysics Data System (ADS)

    Us Saleheen, Ahmad; Samanta, Tapas; Lepkowski, Daniel; Shankar, Alok; Prestigiacomo, Joseph; Dubenko, Igor; Quetz, Abdiel; McDougald, Roy, Jr.; McCandless, Gregory; Chan, Julia; Adams, Philip; Young, David; Ali, Naushad; Stadler, Shane

    2015-03-01

    The formation of a Kondo lattice results in a wide variety of exotic phenomena associated with the competition between the Kondo effect and the RKKY interaction, such as heavy fermions, non-Fermi liquid behavior, unconventional superconductivity, and so on. A quantum critical point (QCP) has been frequently observed at the boundaries of competing phases for antiferromagnetic materials. However, the existence of a ferromagnetic (FM) QCP is unclear. Moreover, FM Kondo lattices are rare. Here we report the discovery of a FM Kondo lattice system Mn1-xFexCoGe, which is the first example of a 3d-metal-based system (i.e., not rare-earth-based). Resistivity, magnetic susceptibility, heat capacity and thermopower studies on a single crystal sample indicate that the anisotropic FM kondo lattice has formed along c-axis. The signature of a spin density wave transition was also observed above the Kondo minimum, below which the resistivity follows a log(T) behavior. This work was supported by the U.S. Department of Energy (Grant Nos. DE-FG02-13ER46946 and DE-FG02-06ER46291).

  20. Electronic and spectroscopic properties of early 3d metal atoms on a graphite surface

    NASA Astrophysics Data System (ADS)

    Rakotomahevitra, A.; Garreau, G.; Demangeat, C.; Parlebas, J. C.

    1995-07-01

    High-sensitivity magneto-optic Kerr effect experiments failed to detect manifestations of magnetism in epitaxial films of V on Ag(100) substrates. More recently V 3s XPS of freshly evaporated V clusters on graphite exhibited the appearance of a satellite structure which has then been interpreted by the effect of surface magnetic moments on V. It is the absence of unambiguous results on the electronic properties of early 3d supported metals that prompts us to examine the problem. Our purpose is twofold. In a first part, after a total energy calculation within a tight-binding method which yields the equilibrium position of a given adatom, we use the Hartree-Fock approximation to find out a possible magnetic solution of V (or Cr) upon graphite for a reasonable value of the exchange integral Jdd. In a second part the informations given by the density of states of the graphite surface as well as the additional states of the adsorbed atom are taken into account through a generalised impurity Anderson Hamiltonian which incorporates the various Coulomb and exchange interactions necessary to analyse the 3s XPS results.

  1. Analysis of simple 2-D and 3-D metal structures subjected to fragment impact

    NASA Technical Reports Server (NTRS)

    Witmer, E. A.; Stagliano, T. R.; Spilker, R. L.; Rodal, J. J. A.

    1977-01-01

    Theoretical methods were developed for predicting the large-deflection elastic-plastic transient structural responses of metal containment or deflector (C/D) structures to cope with rotor burst fragment impact attack. For two-dimensional C/D structures both, finite element and finite difference analysis methods were employed to analyze structural response produced by either prescribed transient loads or fragment impact. For the latter category, two time-wise step-by-step analysis procedures were devised to predict the structural responses resulting from a succession of fragment impacts: the collision force method (CFM) which utilizes an approximate prediction of the force applied to the attacked structure during fragment impact, and the collision imparted velocity method (CIVM) in which the impact-induced velocity increment acquired by a region of the impacted structure near the impact point is computed. The merits and limitations of these approaches are discussed. For the analysis of 3-d responses of C/D structures, only the CIVM approach was investigated.

  2. Accurate nonrelativistic ground-state energies of 3d transition metal atoms

    SciTech Connect

    Scemama, A.; Applencourt, T.; Giner, E.; Caffarel, M.

    2014-12-28

    We present accurate nonrelativistic ground-state energies of the transition metal atoms of the 3d series calculated with Fixed-Node Diffusion Monte Carlo (FN-DMC). Selected multi-determinantal expansions obtained with the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) method and including the most prominent determinants of the full configuration interaction expansion are used as trial wavefunctions. Using a maximum of a few tens of thousands determinants, fixed-node errors on total DMC energies are found to be greatly reduced for some atoms with respect to those obtained with Hartree-Fock nodes. To the best of our knowledge, the FN-DMC/(CIPSI nodes) ground-state energies presented here are the lowest variational total energies reported so far. They differ from the recently recommended non-variational values of McCarthy and Thakkar [J. Chem. Phys. 136, 054107 (2012)] only by a few percents of the correlation energy. Thanks to the variational property of FN-DMC total energies, our results provide exact lower bounds for the absolute value of all-electron correlation energies, |E{sub c}|.

  3. Microscopic magnetic nature of K2NiF4-type 3d transition metal oxides

    NASA Astrophysics Data System (ADS)

    Sugiyama, J.; Nozaki, H.; Umegaki, I.; Higemoto, W.; Ansaldo, E. J.; Brewer, J. H.; Sakurai, H.; Kao, T.-H.; Yang, H.-D.; Månsson, M.

    2014-12-01

    In order to elucidate the magnetic nature of K2NiF4-type 3d transition metal oxides, we have measured μ+SR spectra for Sr2VO4, LaSrVO4, and Sr2CrO4 using powder samples. ZF- and wTF-μ+SR measurements propose that Sr2VO4 enters into the static antiferromagnetic (AF) order phase below 8 K. In addition, TF-μ+SR measurements evidence that the transition at 105 K is not magnetic but structural and/or electronic in origin. For LaSrVO4, static long-range order has not been observed down to 20 K, while, as T decreases from 145 K, wTF asymmetry starts to decrease below 60 K, suggesting the appearance and evolution of localized magnetic moments below 60 K. For Sr2CrO4, by contrast, both ZF- and wTF-μ+SR have confirmed the presence of antiferromagnetic order below 117 K, as predicted in the χ(T) curve.

  4. Understanding the spin-driven polarizations in Bi MO3 (M = 3 d transition metals) multiferroics

    NASA Astrophysics Data System (ADS)

    Kc, Santosh; Lee, Jun Hee; Cooper, Valentino R.

    Bismuth ferrite (BiFeO3) , a promising multiferroic, stabilizes in a perovskite type rhombohedral crystal structure (space group R3c) at room temperature. Recently, it has been reported that in its ground state it possess a huge spin-driven polarization. To probe the underlying mechanism of this large spin-phonon response, we examine these couplings within other Bi based 3 d transition metal oxides Bi MO3 (M = Ti, V, Cr, Mn, Fe, Co, Ni) using density functional theory. Our results demonstrate that this large spin-driven polarization is a consequence of symmetry breaking due to competition between ferroelectric distortions and anti-ferrodistortive octahedral rotations. Furthermore, we find a strong dependence of these enhanced spin-driven polarizations on the crystal structure; with the rhombohedral phase having the largest spin-induced atomic distortions along [111]. These results give us significant insights into the magneto-electric coupling in these materials which is essential to the magnetic and electric field control of electric polarization and magnetization in multiferroic based devices. Research is supported by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Engineering Division and the Office of Science Early Career Research Program (V.R.C) and used computational resources at NERSC.

  5. Kh a 1,2 hyperesatellites of 3d transition metals and their photoexcitation energy dependence.

    SciTech Connect

    Diamant, R.; Kao, C.; Huotari, S; Hamalainen, K; Sharon, R; Deutsch, M.

    2009-06-25

    Hollow atoms in which the K shell is empty while the outer shells are populated allow studying a variety of important and unusual properties of atoms. The diagram x-ray emission lines of such atoms, the K{sup h} {alpha}{sub 1,2} hypersatellites (HSs), were measured for the 3d transition metals, Z = 23-30, with a high energy resolution using photoexcitation by monochromatized synchrotron radiation. Good agreement with ab initio relativistic multiconfigurational Dirac-Fock calculations was found. The measured HS intensity variation with the excitation energy yields accurate values for the excitation thresholds, excludes contributions from shake-up processes, and indicates domination near threshold of a nonshake process. The Z variation of the HS shifts from the diagram line K{alpha}{sub 1,2}, the K{sup h}{alpha}{sub 1}-K{sup h}{alpha}{sub 2} splitting, and the K{sup h}{alpha}{sub 1}/K{sup h}{alpha}{sub 2} intensity ratio, derived from the measurements, are also discussed with a particular emphasis on the QED corrections and Breit interaction.

  6. An accurate and efficient 3-D micromagnetic simulation of metal evaporated tape

    NASA Astrophysics Data System (ADS)

    Jones, M.; Miles, J. J.

    1997-07-01

    Metal evaporated tape (MET) has a complex column-like structure in which magnetic domains are arranged randomly. In order to accurately simulate the behaviour of MET it is important to capture these aspects of the material in a high-resolution 3-D micromagnetic model. The scale of this problem prohibits the use of traditional scalar computers and leads us to develop algorithms for a vector processor architecture. We demonstrate that despite the materials highly non-uniform structure, it is possible to develop fast vector algorithms for the computation of the magnetostatic interaction field. We do this by splitting the field calculation into near and far components. The near field component is calculated exactly using an efficient vector algorithm, whereas the far field is calculated approximately using a novel fast Fourier transform (FFT) technique. Results are presented which demonstrate that, in practice, the algorithms require sub-O( N log( N)) computation time. In addition results of highly realistic simulation of hysteresis in MET are presented.

  7. Dual focused coherent beams for three-dimensional optical trapping and continuous rotation of metallic nanostructures

    PubMed Central

    Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun

    2016-01-01

    Metallic nanoparticles and nanowires are extremely important for nanoscience and nanotechnology. Techniques to optically trap and rotate metallic nanostructures can enable their potential applications. However, because of the destabilizing effects of optical radiation pressure, the optical trapping of large metallic particles in three dimensions is challenging. Additionally, the photothermal issues associated with optical rotation of metallic nanowires have far prevented their practical applications. Here, we utilize dual focused coherent beams to realize three-dimensional (3D) optical trapping of large silver particles. Continuous rotation of silver nanowires with frequencies measured in several hertz is also demonstrated based on interference-induced optical vortices with very low local light intensity. The experiments are interpreted by numerical simulations and calculations. PMID:27386838

  8. Dual focused coherent beams for three-dimensional optical trapping and continuous rotation of metallic nanostructures.

    PubMed

    Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun

    2016-01-01

    Metallic nanoparticles and nanowires are extremely important for nanoscience and nanotechnology. Techniques to optically trap and rotate metallic nanostructures can enable their potential applications. However, because of the destabilizing effects of optical radiation pressure, the optical trapping of large metallic particles in three dimensions is challenging. Additionally, the photothermal issues associated with optical rotation of metallic nanowires have far prevented their practical applications. Here, we utilize dual focused coherent beams to realize three-dimensional (3D) optical trapping of large silver particles. Continuous rotation of silver nanowires with frequencies measured in several hertz is also demonstrated based on interference-induced optical vortices with very low local light intensity. The experiments are interpreted by numerical simulations and calculations. PMID:27386838

  9. Dual focused coherent beams for three-dimensional optical trapping and continuous rotation of metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun

    2016-07-01

    Metallic nanoparticles and nanowires are extremely important for nanoscience and nanotechnology. Techniques to optically trap and rotate metallic nanostructures can enable their potential applications. However, because of the destabilizing effects of optical radiation pressure, the optical trapping of large metallic particles in three dimensions is challenging. Additionally, the photothermal issues associated with optical rotation of metallic nanowires have far prevented their practical applications. Here, we utilize dual focused coherent beams to realize three-dimensional (3D) optical trapping of large silver particles. Continuous rotation of silver nanowires with frequencies measured in several hertz is also demonstrated based on interference-induced optical vortices with very low local light intensity. The experiments are interpreted by numerical simulations and calculations.

  10. Synthesis, surface group modification of 3D MnV{sub 2}O{sub 6} nanostructures and adsorption effect on Rhodamine B

    SciTech Connect

    Zhang, Wanqun; Shi, Lei; Tang, Kaibin; Liu, Zhongping

    2012-07-15

    Highlights: ► Fabrication of urchin-like MnV{sub 2}O{sub 6} with oxygen-containing surface groups. ► Mn{sub 0.5}V{sub 2}O{sub 5}·nH{sub 2}O as an intermediate product holds the key to the final products. ► 3D architectures of MnV{sub 2}O{sub 6} with oxygen-containing surface groups as sorbent. ► The sorbent shows a good adsorption ability. -- Abstract: Highly uniform 3D MnV{sub 2}O{sub 6} nanostructures modified by oxygen functional groups (-COO-) were successfully prepared in large quantities by an approach involving preparation of vanadyl ethylene glycolate as the precursor. The growth and self-assembly of MnV{sub 2}O{sub 6} nanobelts and nanorods could be readily tuned by additive species and quantities, which brought different morphologies and sizes to the final products. With a focus on the regulation of structure, the formation process of 3D architectures of MnV{sub 2}O{sub 6} by self-assembly of nanobelts was followed by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The consecutive processes of vanadyl ethylene glycolate and benzoyl peroxide assisted formation of layered structure Mn{sub 0.5}V{sub 2}O{sub 5}·nH{sub 2}O, growth of aligned MnV{sub 2}O{sub 6} nanobelts, and oriented assembly were proposed for the growth mechanism. The band gap vs. different morphology was also studied. Optical characterization of these MnV{sub 2}O{sub 6} with different morphologies showed direct bandgap energies at 1.8–1.95 eV. The adsorption properties of 3D MnV{sub 2}O{sub 6} nanostructures synthesized under different conditions were investigated through the removal test of Rhodamine B in aqueous water, and the 3D nanostructures synthesized with 30 g L{sup −1} benzoyl peroxide showed good adsorption capability of Rhodamine B.

  11. Stabilizing nanostructures in metals using grain and twin boundary architectures

    NASA Astrophysics Data System (ADS)

    Lu, K.

    2016-05-01

    Forming alloys with impurity elements is a routine method for modifying the properties of metals. An alternative approach involves the incorporation of interfaces into the crystalline lattice to enhance the metal's properties without changing its chemical composition. The introduction of high-density interfaces in nanostructured materials results in greatly improved strength and hardness; however, interfaces at the nanoscale show low stability. In this Review, I discuss recent developments in the stabilization of nanostructured metals by modifying the architectures of their interfaces. The amount, structure and distribution of several types of interfaces, such as high- and low-angle grain boundaries and twin boundaries, are discussed. I survey several examples of materials with nanotwinned and nanolaminated structures, as well as with gradient nanostructures, describing the techniques used to produce such samples and tracing their exceptional performances back to the nanoscale architectures of their interfaces.

  12. Transient absorption microscopy studies of single metal and semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Johns, Paul; Sajini-Devadas, Mary; Hartland, Gregory V.

    2015-08-01

    Transient absorption microscopy is an experimental technique that allows nanomaterials to be studied with ultrafast time resolution and diffraction limited spatial resolution. This paper describes recent results from using transient absorption microscopy to investigate energy relaxation processes in single metal and semiconductor nanowires. The processes that have been examined include charge carrier trapping in semiconductor nanostructures, the motion of surface plasmon polaritons in metal nanowires, and the damping of the acoustic breathing modes of metal nanowires by high viscosity solvents.

  13. Carbon monoxide-induced dynamic metal-surface nanostructuring.

    PubMed

    Carenco, Sophie

    2014-08-18

    Carbon monoxide is a ubiquitous molecule in surface science, materials chemistry, catalysis and nanotechnology. Its interaction with a number of metal surfaces is at the heart of major processes, such as Fischer-Tropsch synthesis or fuel-cell optimization. Recent works, coupling structural and nanoscale in situ analytic tools have highlighted the ability of metal surfaces and nanoparticles to undergo restructuring after exposure to CO under fairly mild conditions, generating nanostructures. This Minireview proposes a brief overview of recent examples of such nanostructuring, which leads to a discussion about the driving force in reversible and non-reversible situations. PMID:25044189

  14. Hydrothermal synthesis of WO3·H2O with different nanostructures from 0D to 3D and their gas sensing properties

    NASA Astrophysics Data System (ADS)

    Yu, Yangchun; Zeng, Wen; Xu, Mengxue; Peng, Xianghe

    2016-05-01

    In this paper, WO3·H2O with different nanostructures from 0D to 3D were successfully synthesized via a simple yet cost-effective hydrothermal method with the assistance of surfactants. The structures and morphologies of products were investigated by XRD and SEM. Besides, we systematically explained the evolution process and formation mechanisms of different WO3·H2O morphologies. It is noted that both the kinds and amounts of surfactants strongly affect the formation of WO3·H2O crystals, as reflected in the tailoring of WO3·H2O morphologies. Furthermore, the gas sensing performance of the as-prepared samples towards methanol was also investigated. 3D flower-like hierarchical architecture displayed outstanding response to target gas among the four samples. We hoped our results could be of great benefit to further investigations of synthesizing different dimensional WO3·H2O nanostructures and their gas sensing applications.

  15. Effect of anchor positioning on binding and diffusion of elongated 3D DNA nanostructures on lipid membranes

    NASA Astrophysics Data System (ADS)

    Khmelinskaia, Alena; Franquelim, Henri G.; Petrov, Eugene P.; Schwille, Petra

    2016-05-01

    DNA origami is a state-of-the-art technology that enables the fabrication of nano-objects with defined shapes, to which functional moieties, such as lipophilic anchors, can be attached with a nanometre scale precision. Although binding of DNA origami to lipid membranes has been extensively demonstrated, the specific requirements necessary for membrane attachment are greatly overlooked. Here, we designed a set of amphipathic rectangular-shaped DNA origami structures with varying placement and number of chol-TEG anchors used for membrane attachment. Single- and multiple-cholesteryl-modified origami nanostructures were produced and studied in terms of their membrane localization, density and dynamics. We show that the positioning of at least two chol-TEG moieties near the corners is essential to ensure efficient membrane binding of large DNA nanostructures. Quantitative fluorescence correlation spectroscopy data further confirm that increasing the number of corner-positioned chol-TEG anchors lowers the dynamics of flat DNA origami structures on freestanding membranes. Taken together, our approach provides the first evidence of the importance of the location in addition to the number of hydrophobic moieties when rationally designing minimal DNA nanostructures with controlled membrane binding.

  16. Methods of making metal oxide nanostructures and methods of controlling morphology of same

    DOEpatents

    Wong, Stanislaus S; Hongjun, Zhou

    2012-11-27

    The present invention includes a method of producing a crystalline metal oxide nanostructure. The method comprises providing a metal salt solution and providing a basic solution; placing a porous membrane between the metal salt solution and the basic solution, wherein metal cations of the metal salt solution and hydroxide ions of the basic solution react, thereby producing a crystalline metal oxide nanostructure.

  17. PVP Assisted Shape-Controlled Synthesis of Self-Assembled 1D ZnO and 3D CuO Nanostructures

    NASA Astrophysics Data System (ADS)

    Haque, Fozia Z.; Parra, Mohammad Ramzan; Siddiqui, Hafsa; Singh, Neha; Singh, Nitu; Pandey, Padmini; Mishra, K. M.

    2016-03-01

    Self-assembled one-dimensional (1D) zinc oxide (ZnO) rods and three-dimensional (3D) cupric oxide (CuO) cubes like nanostructures with a mean crystallite size of approximately 33 and 32 nm were synthesized through chemical route in the presence of polyvinylpyrrolidone (PVP) under mild synthesis conditions. The technique used for the synthesis of nanoparticles seems to be an efficient, inexpensive and easy method. X-Ray diffraction patterns confirmed well crystallinity and phase purity of the as prepared samples, followed by the compositional investigation using Fourier Transform Infrared (FT-IR) spectroscopy. The formation of ZnO nanorods and CuO nanocubes like structures were through Scanning Electron Microscopy (SEM) images. The mechanism and the formation factors of the self-assembly were discussed in detail. It was clearly observed from results that the concentration of precursors and PVP were important factors in the synthesis of self-assembly ZnO and CuO nanostructures. These self-assembly nanostructures maybe used as novel materials in various potential applications.

  18. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells.

    PubMed

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, JunHo; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-07-01

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells. PMID:26061271

  19. Electrochemical Synthesis of Nanostructured Noble Metal Films for Biosensing

    NASA Astrophysics Data System (ADS)

    Bhattarai, Jay K.

    Nanostructures of noble metals (gold and silver) are of interest because of their important intrinsic properties. Noble metals by themselves are physically robust, chemically inert, highly conductive, and possess the capability to form strong bonds with thiols or dithiol molecules present in organic compounds, creating self-assembled monolayers with tunable functional groups at exposed interfaces. However, when the nanostructures are formed, they in addition possess high surface area and unique optical properties which can be tuned by adjusting the shape and the size of the nanostructures. All of these properties make nanostructures of noble metals suitable candidates to be used as a transducer for optical and electrochemical biosensing. Individual nanostructures might be easier to prepare but difficult to handle to use as a transducer. Therefore, we prepared and analyzed nanostructured films/coating of noble metals and used them as a transducer for optical and electrochemical biosensing. We have electrochemically prepared nanoporous gold (NPG) on gold wire varying different dependable parameters (deposition potential, time, and compositional ratio) to obtain an optimal structure in term of stability, morphology, and better surface area. NPG prepared using a deposition potential of --1.0 V for 10 min from 30:70% 50 mM potassium dicyanoaurate(I) and 50 mM potassium dicyanoargentate(I) was used as an optimal surface for protein immobilization, and to perform square wave voltammetry (SWV) based enzyme-linked lectinsorbent assays. On flat gold surfaces, adjacent protein molecules sterically block their active sites due to high-density packing, which can be minimized using NPG as a substrate. NPG can also show significant peak current in SWV experiments, a sensitive electrochemical technique that minimizes non-Faradaic current, which is difficult to obtain using a flat gold surface. These all make NPG a suitable substrate, electrode, and transducer to be used in

  20. Nanostructuring of metals by severe plastic deformation for advanced properties

    NASA Astrophysics Data System (ADS)

    Valiev, Ruslan

    2004-08-01

    Despite rosy prospects, the use of nanostructured metals and alloys as advanced structural and functional materials has remained controversial until recently. Only in recent years has a breakthrough been outlined in this area, associated both with development of new routes for the fabrication of bulk nanostructured materials and with investigation of the fundamental mechanisms that lead to the new properties of these materials. Although a deep understanding of these mechanisms is still a topic of basic research, pilot commercial products for medicine and microdevices are coming within reach of the market. This progress article discusses new concepts and principles of using severe plastic deformation (SPD) to fabricate bulk nanostructured metals with advanced properties. Special emphasis is laid on the relationship between microstructural features and properties, as well as the first applications of SPD-produced nanomaterials.

  1. Magnetic interactions between metal nanostructures within porous silicon

    PubMed Central

    2014-01-01

    Electrochemically deposited magnetic nanostructures arranged in a three-dimensional system are investigated with respect to their cross-talk between each other. The nanostructures are embedded in porous silicon templates with different morphologies which means pores offering dendritic growth of different strengths. An increase of the uniformity of the pores is concomitant with an increase of the smoothness of the metal deposits which strongly influences the magnetic behavior of the system. Less dendritic structures lead to an increase of the coercivity of the nanocomposite which reveals less cross-talk between the metal deposits due to a modification of the stray fields. The system allows in a cheap and simple way to tune the magnetic interactions of magnetic nanostructures in a three-dimensional arrangement. PACS 81.05.Rm; 81.07.Gf; 75.75.-c PMID:25177223

  2. Synergistic Behavior of Tubes, Junctions, and Sheets Imparts Mechano-Mutable Functionality in 3D Porous Boron Nitride Nanostructures

    PubMed Central

    2015-01-01

    One-dimensional (1D) boron nitride nanotube (BNNT) and 2D hexagonal BN (h-BN) are attractive for demonstrating fundamental physics and promising applications in nano-/microscale devices. However, there is a high anisotropy associated with these BN allotropes as their excellent properties are either along the tube axis or in-plane directions, posing an obstacle in their widespread use in technological and industrial applications. Herein, we report a series of 3D BN prototypes, namely, pillared boron nitride (PBN), by fusing single-wall BNNT and monolayer h-BN aimed at filling this gap. We use density functional theory and molecular dynamics simulations to probe the diverse mechano-mutable properties of PBN prototypes. Our results demonstrate that the synergistic effect of the tubes, junctions, and sheets imparts cooperative deformation mechanisms, which overcome the intrinsic limitations of the PBN constituents and provide a number of superior characteristics including 3D balance of strength and toughness, emergence of negative Poisson’s ratio, and elimination of strain softening along the armchair orientation. These features, combined with the ultrahigh surface area and lightweight structure, render PBN as a 3D multifunctional template for applications in graphene-based nanoelectronics, optoelectronics, gas storage, and functional composites with fascinating in-plane and out-of-plane tailorable properties. PMID:25289114

  3. Helical metallic micro- and nanostructures: fabrication and application.

    PubMed

    Liu, Lichun; Zhang, Liqiu; Kim, Sang Min; Park, Sungho

    2014-08-21

    Metal elements occupy more than 70% of the positions in the periodic table, and their use has accelerated human civilization due to their invaluable chemical and physical characteristics. With the rapid development of metals, various structures of microscopic metal particles have been fabricated and investigated as functional materials in scientific research and practical applications. The phrase 'structure determines properties' has been widely acknowledged as a golden rule in chemistry and materials science, especially when the size of small particles is in the micro- or nanoscale dimension. Helical metallic micro- and nanostructures with complex shapes have recently emerged and may be used for various useful applications such as photonics, sensors, actuators, micro-/nanorobotics, and micro-/nanoelectronics, based on their unique mechanical, electrical, and electromagnetic properties. This review paper specifically focuses on the fabrication and application of helical metallic structures with a size ranging from the micro- to nanoscale. The unusual spatial distribution of active atoms in helical metallic micro- and nanostructures and their helical morphology could offer new opportunities for applications beyond those of other conventional metallic and nonmetallic micro- and nanostructures. PMID:24770884

  4. Helical metallic micro- and nanostructures: fabrication and application

    NASA Astrophysics Data System (ADS)

    Liu, Lichun; Zhang, Liqiu; Kim, Sang Min; Park, Sungho

    2014-07-01

    Metal elements occupy more than 70% of the positions in the periodic table, and their use has accelerated human civilization due to their invaluable chemical and physical characteristics. With the rapid development of metals, various structures of microscopic metal particles have been fabricated and investigated as functional materials in scientific research and practical applications. The phrase `structure determines properties' has been widely acknowledged as a golden rule in chemistry and materials science, especially when the size of small particles is in the micro- or nanoscale dimension. Helical metallic micro- and nanostructures with complex shapes have recently emerged and may be used for various useful applications such as photonics, sensors, actuators, micro-/nanorobotics, and micro-/nanoelectronics, based on their unique mechanical, electrical, and electromagnetic properties. This review paper specifically focuses on the fabrication and application of helical metallic structures with a size ranging from the micro- to nanoscale. The unusual spatial distribution of active atoms in helical metallic micro- and nanostructures and their helical morphology could offer new opportunities for applications beyond those of other conventional metallic and nonmetallic micro- and nanostructures.

  5. Micro- to nanostructured poly(pyrrole-nitrilotriacetic acid) films via nanosphere templates: applications to 3D enzyme attachment by affinity interactions.

    PubMed

    Cernat, Andreea; Le Goff, Alan; Holzinger, Michael; Sandulescu, Robert; Cosnier, Serge

    2014-02-01

    We report the combination of latex nanosphere lithography with electropolymerization of N-substituted pyrrole monomer bearing a nitrilotriacetic acid (NTA) moiety for the template-assisted nanostructuration of poly(pyrrole-NTA) films and their application for biomolecule immobilization. The electrodes were modified by casting latex beads (100 or 900 nm in diameter) on their surface followed by electropolymerization of the pyrrole-NTA monomer and the subsequent chelation of Cu(2+) ions. The dissolution of the nanobeads leads then to a nanostructured polymer film with increased surface. Thanks to the versatile affinity interactions between the (NTA)Cu(2+) complex and histidine- or biotin-tagged proteins, both tyrosinase and glucose oxidase were immobilized on the modified electrode. Nanostructuration of the polypyrrole via nanosphere lithography (NSL) using 900- and 100-nm latex beads allows an increase in surface concentration of enzymes anchored on the functionalized polypyrrole electrode. The nanostructured enzyme electrodes were characterized by fluorescence microscopy, 3D laser scanning confocal microscopy, and scanning electron microscopy. Electrochemical studies demonstrate the increase in the amount of immobilized biomolecules and associated biosensor performances when achieving NSL compared to conventional polymer formation without bead template. In addition, the decrease in nanobead diameter from 900 to 100 nm provides an enhancement in biosensor performance. Between biosensors based on films polymerized without nanobeads and with 100-nm nanobeads, maximum current density values increase from 4 to 56 μA cm(-2) and from 7 to 45 μA cm(-2) for biosensors based on tyrosinase and glucose oxidase, respectively. PMID:23793398

  6. The performance of semilocal and hybrid density functionals in 3d transition-metal chemistry

    NASA Astrophysics Data System (ADS)

    Furche, Filipp; Perdew, John P.

    2006-01-01

    We investigate the performance of contemporary semilocal and hybrid density functionals for bond energetics, structures, dipole moments, and harmonic frequencies of 3d transition-metal (TM) compounds by comparison with gas-phase experiments. Special attention is given to the nonempirical metageneralized gradient approximation (meta-GGA) of Tao, Perdew, Staroverov, and Scuseria (TPSS) [Phys. Rev. Lett. 91, 146401 (2003)], which has been implemented in TURBOMOLE for the present work. Trends and error patterns for classes of homologous compounds are analyzed, including dimers, monohydrides, mononitrides, monoxides, monofluorides, polyatomic oxides and halogenides, carbonyls, and complexes with organic π ligands such as benzene and cyclopentadienyl. Weakly bound systems such as Ca2, Mn2, and Zn2 are discussed. We propose a reference set of reaction energies for benchmark purposes. Our all-electron results with quadruple zeta valence basis sets validate semilocal density-functional theory as the workhorse of computational TM chemistry. Typical errors in bond energies are substantially larger than in (organic) main group chemistry, however. The Becke-Perdew'86 [Phys. Rev. A 38, 3098 (1988); Phys. Rev. B 33, 8822 (1986)] GGA and the TPSS meta-GGA have the best price/performance ratio, while the TPSS hybrid functional achieves a slightly lower mean absolute error in bond energies. The popular Becke three-parameter hybrid B3LYP underbinds significantly and tends to overestimate bond distances; we give a possible explanation for this. We further show that hybrid mixing does not reduce the width of the error distribution on our reference set. The error of a functional for the s-d transfer energy of a TM atom does not predict its error for TM bond energies and bond lengths. For semilocal functionals, self-interaction error in one- and three-electron bonds appears to be a major source of error in TM reaction energies. Nevertheless, TPSS predicts the correct ground

  7. The Evolution of Metallicity and Metallicity Gradients from z = 2.7 to 0.6 with KMOS3D

    NASA Astrophysics Data System (ADS)

    Wuyts, Eva; Wisnioski, Emily; Fossati, Matteo; Förster Schreiber, Natascha M.; Genzel, Reinhard; Davies, Ric; Mendel, J. Trevor; Naab, Thorsten; Röttgers, Bernhard; Wilman, David J.; Wuyts, Stijn; Bandara, Kaushala; Beifiori, Alessandra; Belli, Sirio; Bender, Ralf; Brammer, Gabriel B.; Burkert, Andreas; Chan, Jeffrey; Galametz, Audrey; Kulkarni, Sandesh K.; Lang, Philipp; Lutz, Dieter; Momcheva, Ivelina G.; Nelson, Erica J.; Rosario, David; Saglia, Roberto P.; Seitz, Stella; Tacconi, Linda J.; Tadaki, Ken-ichi; Übler, Hannah; van Dokkum, Pieter

    2016-08-01

    We present measurements of the [N ii]/Hα ratio as a probe of gas-phase oxygen abundance for a sample of 419 star-forming galaxies at z = 0.6–2.7 from the KMOS3D near-IR multi-integral field unit (IFU) survey. The mass–metallicity relation (MZR) is determined consistently with the same sample selection, metallicity tracer, and methodology over the wide redshift range probed by the survey. We find good agreement with long-slit surveys in the literature, except for the low-mass slope of the relation at z˜ 2.3, where this sample is less biased than previous samples based on optical spectroscopic redshifts. In this regime we measure a steeper slope than some literature results. Excluding the contribution from active galactic nuclei from the MZR reduces sensitivity at the high-mass end, but produces otherwise consistent results. There is no significant dependence of the [N ii]/Hα ratio on star formation rate at fixed redshift and stellar mass. The IFU data allow spatially resolved measurements of [N ii]/Hα, from which we can infer abundance gradients for 180 galaxies, thus tripling the current sample in the literature. The observed gradients are on average flat, with only 15 gradients statistically offset from zero at \\gt 3σ . We have modeled the effect of beam smearing, assuming a smooth intrinsic radial gradient and known seeing, inclination, and effective radius for each galaxy. Our seeing-limited observations can recover up to 70% of the intrinsic gradient for the largest, face-on disks, but only 30% for the smaller, more inclined galaxies. We do not find significant trends between observed or corrected gradients and any stellar population, dynamical, or structural galaxy parameters, mostly in agreement with existing studies with much smaller sample sizes. In cosmological simulations, strong feedback is generally required to produce flat gradients at high redshift.

  8. Nanostructured TTT(TCNQ)2 Organic Crystals as Promising Thermoelectric n-Type Materials: 3D Modeling

    NASA Astrophysics Data System (ADS)

    Sanduleac, Ionel; Casian, Anatolie

    2016-03-01

    The thermoelectric properties of quasi-one-dimensional TTT(TCNQ)2 organic crystals have been investigated to assess the prospect of using this type of compound as an n-type thermoelectric material. A three-dimensional (3D) physical model was elaborated. This takes into account two of the most important interactions of conduction electrons with longitudinal acoustic phonons—scattering of the electrons' by neighboring molecular chains and scattering by impurities and defects. Electrical conductivity, thermopower, power factor, electronic thermal conductivity, and thermoelectric figure of merit in the direction along the conducting molecular chains were calculated numerically for different crystal purity. It was shown that in stoichiometric compounds the thermoelectric figure of merit ZT remains small even after an increase of crystal perfection. The thermoelectric properties may be significantly enhanced by simultaneous increases of crystal perfection and electron concentration. The latter can be achieved by additional doping with donors. For less pure crystals, the interaction with impurities dominates the weak interchain interaction and the simpler one-dimensional (1D) physical model is applicable. When the impurity scattering is reduced, the interchain interaction begins to limit carrier mobility and use of the 3D physical model is required. The optimum properties enabling prediction of ZT ˜ 1 were determined.

  9. Metal Oxide Nanostructures and Their Gas Sensing Properties: A Review

    PubMed Central

    Sun, Yu-Feng; Liu, Shao-Bo; Meng, Fan-Li; Liu, Jin-Yun; Jin, Zhen; Kong, Ling-Tao; Liu, Jin-Huai

    2012-01-01

    Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on. Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping. When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called “small size effect”, yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them. In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion. Besides, doping is also an effective method to decrease particle size and improve gas sensing properties. Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article. The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given. PMID:22736968

  10. Plasmon-enhanced fluorescence near metallic nanostructures: biochemical applications

    NASA Astrophysics Data System (ADS)

    Goldys, E. M.; Barnett, A.; Xie, F.; Drozdowicz-Tomsia, K.; Gryczynski, I.; Matveeva, E. G.; Gryczynski, Z.; Shtoyko, T.

    2007-11-01

    Amplification of fluorescence is a nanoscale phenomenon which is particularly pronounced in close proximity to metal nanostructures. Due to its sharp distance dependence, it is ideally suited to monitor biorecognition reactions. Using this effect we have been able to demonstrate ultrasensitive bioassays. Two types of metal nanostructures have been employed, nanometric silver islands deposited over an ultrathin metal mirror and silver fractal structures. For the first type, metal mirrors (aluminum, gold, or silver protected with a thin silica layer) were coated with SIFs and an immunoassay (model assay for rabbit IgG or myoglobin immunoassay) was performed on this surface using fluorescently labeled antibodies. Our results show that SIFs alone (on a glass surface not coated with metal) enhance the immunoassay signal approximately 3 to 10-fold. Using a metal mirror instead of glass as support for SIFs leads to up to 50-fold signal enhancement. The second type of metal nanostructures, silver fractals, were produced by electrochemical reduction of silver nitrate deposited on sapphire covered with a thin conductive film of indium tin oxide. These structures were used as a substrate for a model rabbit IgG bioassay. The fluorescence resulting from the binding of antibody labeled with Rhodamine was highly nonuniform with distinctive hot spots. These highly fluorescent regions were correlated with areas of higher Ag thickness and coverage. Such high values of fluorescence amplification in both types of nanostructures have been interpreted by using time-resolved fluorescence data and by considering the radiative properties of plasmons in the environments which promote plasmon coupling.

  11. Metal oxide nanostructures and their gas sensing properties: a review.

    PubMed

    Sun, Yu-Feng; Liu, Shao-Bo; Meng, Fan-Li; Liu, Jin-Yun; Jin, Zhen; Kong, Ling-Tao; Liu, Jin-Huai

    2012-01-01

    Metal oxide gas sensors are predominant solid-state gas detecting devices for domestic, commercial and industrial applications, which have many advantages such as low cost, easy production, and compact size. However, the performance of such sensors is significantly influenced by the morphology and structure of sensing materials, resulting in a great obstacle for gas sensors based on bulk materials or dense films to achieve highly-sensitive properties. Lots of metal oxide nanostructures have been developed to improve the gas sensing properties such as sensitivity, selectivity, response speed, and so on. Here, we provide a brief overview of metal oxide nanostructures and their gas sensing properties from the aspects of particle size, morphology and doping. When the particle size of metal oxide is close to or less than double thickness of the space-charge layer, the sensitivity of the sensor will increase remarkably, which would be called "small size effect", yet small size of metal oxide nanoparticles will be compactly sintered together during the film coating process which is disadvantage for gas diffusion in them. In view of those reasons, nanostructures with many kinds of shapes such as porous nanotubes, porous nanospheres and so on have been investigated, that not only possessed large surface area and relatively mass reactive sites, but also formed relatively loose film structures which is an advantage for gas diffusion. Besides, doping is also an effective method to decrease particle size and improve gas sensing properties. Therefore, the gas sensing properties of metal oxide nanostructures assembled by nanoparticles are reviewed in this article. The effect of doping is also summarized and finally the perspectives of metal oxide gas sensor are given. PMID:22736968

  12. Fabrication of 3D Printed Metal Structures by Use of High-Viscosity Cu Paste and a Screw Extruder

    NASA Astrophysics Data System (ADS)

    Hong, Seongik; Sanchez, Cesar; Du, Hanuel; Kim, Namsoo

    2015-03-01

    Three-dimensional (3D) printing is an important, rapidly growing industry. However, traditional 3D printing technology has problems with some materials. To solve the problem of the limited number of 3D-printable materials, high-viscosity materials and a new method for 3D printing were investigated. As an example of a high-viscosity material, Cu paste was synthesized and a screw extruder printer was developed to print the paste. As a fundamental part of the research, the viscosity of the Cu paste was measured for different Cu content. The viscosity of the paste increased with increasing Cu content. To print high-viscosity Cu paste, printing conditions were optimized. 3D structures were printed, by use of an extruder and high-viscosity metal paste with appropriate printing conditions, and then heat treated. After sintering, however, approximately 75% shrinkage of the final product was observed. To achieve less shrinkage, the packing factor of the Cu paste was increased by adding more Cu particles. The shrinkage factor decreased as the packing factor increased, and the size of final product was 77% of that expected.

  13. Three-dimensional fabrication of metallic micro/nanostructures by two-photon polymerization for metamaterials

    NASA Astrophysics Data System (ADS)

    Formanek, Florian; Takeyasu, Nobuyuki; Tanaka, Takuo; Chiyoda, Kenta; Ishikawa, Atsushi; Kawata, Satoshi

    2006-08-01

    We report on selective metal deposition over complex polymer structures formed by two-photon induced photopolymerization (TPP) technique. Periodic three-dimensional (3D) polymer micro/nanostructures are fabricated by means of a microlens array to produce multiple spots from a single-beam femtosecond laser amplified by a regenerative amplifier. The photopolymerizable resin and the glass substrate are chemically modified, and a pre-treatment with SnCl2 is applied before realizing a uniform silver coating by electroless plating. This preparation enables a selective deposition of small silver particles only on the polymer surface all over the sample and to avoid metal deposition on the substrate. Electrical measurements show the structures to be highly conductive with typical resistivities ρ approx. 10 -7 Ωm, only a few times larger than the value for bulk silver. By taking advantage of the high accuracy and arbitrary shape modeling of TPP fabrication, we can realize complex periodic and/or metallic micro-nanostructures which were so far out of reach. Thus, a straightforward application could be the realization of metamaterials. The processing efficiency of our technique is demonstrated with the fabrication of several large samples, created by more than 700 objects written in parallel and metallized with silver.

  14. Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents.

    PubMed

    Štengl, Václav; Henych, Jiří; Janoš, Pavel; Skoumal, Miroslav

    2016-01-01

    Metal oxides have very important applications in many areas of chemistry, physics and materials science; their properties are dependent on the method of preparation, the morphology and texture. Nanostructured metal oxides can exhibit unique characteristics unlike those of the bulk form depending on their morphology, with a high density of edges, corners and defect surfaces. In recent years, methods have been developed for the preparation of metal oxide powders with tunable control of the primary particle size as well as of a secondary particle size: the size of agglomerates of crystallites. One of the many ways to take advantage of unique properties of nanostructured oxide materials is stoichiometric degradation of chemical warfare agents (CWAs) and volatile organic compounds (VOC) pollutants on their surfaces. PMID:26423076

  15. Highly selective luminescence sensing of nitrite and benzaldehyde based on 3d-4f heterometallic metal-organic frameworks.

    PubMed

    Du, Pei-Yao; Gu, Wen; Liu, Xin

    2016-06-01

    Framework-isomeric three-dimensional (3D) Zn-Ln heterometallic metal-organic frameworks, {[Ln2Zn(abtc)2(H2O)4]·2H2O}∞ {Ln = Sm(1), Tb(2)}, were synthesized using a convenient solvothermal reaction. They can serve as excellent sensors for the specific identification of benzaldehyde and NO2(-) through a fluorescence quenching process. PMID:27117937

  16. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells

    NASA Astrophysics Data System (ADS)

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, Junho; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-06-01

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the

  17. Metal sulfide and rare-earth phosphate nanostructures and methods of making same

    DOEpatents

    Wong, Stanislaus; Zhang, Fen

    2014-05-13

    The present invention provides a method of producing a crystalline metal sulfide nanostructure. The metal is a transitional metal or a Group IV metal. In the method, a porous membrane is placed between a metal precursor solution and a sulfur precursor solution. The metal cations of the metal precursor solution and sulfur ions of the sulfur precursor solution react, thereby producing a crystalline metal sulfide nanostructure.

  18. 3D coaxial out-of-plane metallic antennas for filtering and multi-spectral imaging in the infrared range

    PubMed Central

    Jacassi, Andrea; Bozzola, Angelo; Zilio, Pierfrancesco; Tantussi, Francesco; De Angelis, Francesco

    2016-01-01

    We fabricated and investigated a new configuration of 3D coaxial metallic antennas working in the infrared which combines the strong lateral light scattering of vertical plasmonic structures with the selective spectral transmission of 2D arrays of coaxial apertures. The coaxial structures are fabricated with a top-down method based on a template of hollow 3D antennas. Each antenna has a multilayer radial structure consisting of dielectric and metallic materials not achievable in a 2D configuration. A planar metallic layer is inserted normally to the antennas. The outer dielectric shell of the antenna defines a nanometric gap between the horizontal plane and the vertical walls. Thanks to this aperture, light can tunnel to the other side of the plane, and be transmitted to the far field in a set of resonances. These are investigated with finite-elements electromagnetic calculations and with Fourier-transform infrared spectroscopy measurements. The spectral position of the resonances can be tuned by changing the lattice period and/or the antenna length. Thanks to the strong scattering provided by the 3D geometry, the transmission peaks possess a high signal-to-noise ratio even when the illuminated area is less than 2 × 2 times the operation wavelength. This opens new possibilities for multispectral imaging in the IR with wavelength-scale spatial resolution. PMID:27345517

  19. 3D coaxial out-of-plane metallic antennas for filtering and multi-spectral imaging in the infrared range

    NASA Astrophysics Data System (ADS)

    Jacassi, Andrea; Bozzola, Angelo; Zilio, Pierfrancesco; Tantussi, Francesco; de Angelis, Francesco

    2016-06-01

    We fabricated and investigated a new configuration of 3D coaxial metallic antennas working in the infrared which combines the strong lateral light scattering of vertical plasmonic structures with the selective spectral transmission of 2D arrays of coaxial apertures. The coaxial structures are fabricated with a top-down method based on a template of hollow 3D antennas. Each antenna has a multilayer radial structure consisting of dielectric and metallic materials not achievable in a 2D configuration. A planar metallic layer is inserted normally to the antennas. The outer dielectric shell of the antenna defines a nanometric gap between the horizontal plane and the vertical walls. Thanks to this aperture, light can tunnel to the other side of the plane, and be transmitted to the far field in a set of resonances. These are investigated with finite-elements electromagnetic calculations and with Fourier-transform infrared spectroscopy measurements. The spectral position of the resonances can be tuned by changing the lattice period and/or the antenna length. Thanks to the strong scattering provided by the 3D geometry, the transmission peaks possess a high signal-to-noise ratio even when the illuminated area is less than 2 × 2 times the operation wavelength. This opens new possibilities for multispectral imaging in the IR with wavelength-scale spatial resolution.

  20. 3D coaxial out-of-plane metallic antennas for filtering and multi-spectral imaging in the infrared range.

    PubMed

    Jacassi, Andrea; Bozzola, Angelo; Zilio, Pierfrancesco; Tantussi, Francesco; De Angelis, Francesco

    2016-01-01

    We fabricated and investigated a new configuration of 3D coaxial metallic antennas working in the infrared which combines the strong lateral light scattering of vertical plasmonic structures with the selective spectral transmission of 2D arrays of coaxial apertures. The coaxial structures are fabricated with a top-down method based on a template of hollow 3D antennas. Each antenna has a multilayer radial structure consisting of dielectric and metallic materials not achievable in a 2D configuration. A planar metallic layer is inserted normally to the antennas. The outer dielectric shell of the antenna defines a nanometric gap between the horizontal plane and the vertical walls. Thanks to this aperture, light can tunnel to the other side of the plane, and be transmitted to the far field in a set of resonances. These are investigated with finite-elements electromagnetic calculations and with Fourier-transform infrared spectroscopy measurements. The spectral position of the resonances can be tuned by changing the lattice period and/or the antenna length. Thanks to the strong scattering provided by the 3D geometry, the transmission peaks possess a high signal-to-noise ratio even when the illuminated area is less than 2 × 2 times the operation wavelength. This opens new possibilities for multispectral imaging in the IR with wavelength-scale spatial resolution. PMID:27345517

  1. Nanostructured exchange coupled hard/soft composites: From the local magnetization profile to an extended 3d simple model

    NASA Astrophysics Data System (ADS)

    Russier, V.; Younsi, K.; Bessais, L.

    2012-03-01

    In nanocomposite magnetic materials the exchange coupling between phases plays a central role in the determination of the extrinsic magnetic properties of the material: coercive field,remanence magnetization. Exchange coupling is therefore of crucial importance in composite systems made of magnetically hard and soft grains or in partially crystallized media including nanosized crystallites in a soft matrix. It has been shown also to be a key point in the control of stratified hard/soft media coercive field in the research for optimized recording media. A signature of the exchange coupling due to the nanostructure is generally obtained on the magnetization curve M(H) with a plateau characteristic of the domain wall compression at the hard/soft interface ending at the depinning of the wall inside the hard phase. This compression/depinning behavior is clearly evidenced through one dimensional description of the interface, which is rigorously possible only in stratified media. Starting from a local description of the hard/soft interface in a model for nanocomposite system we show that one can extend this kind of behavior for system of hard crystallites embedded in a soft matrix.

  2. Shape memory in nanostructured metallic alloys

    NASA Astrophysics Data System (ADS)

    Guda Vishnu, Karthik

    Materials with nanoscale dimensions show mechanical and structural properties different to those at the macro scale and engineering their nanostructure opens up potential avenues for designing materials tailored for a specific application. This work is focused on shape memory materials, an important class of active materials with wide variety of applications in medical, aerospace and automobile industries, due to their two important properties of super-elasticity and shape memory. These unique properties originate from a solid-solid transformation called martensite transformation and the main objectives of this research are to i) study the atomic mechanisms of the martensite transformation, ii) study the effect of nano-structure on shape memory behavior and iii) computationally explore avenues through which their performance is optimized. A combination of density functional theory (DFT) and molecular dynamics (MD) simulations is used to achieve this. This approach gives an atomic level description and the effects of size, surfaces and interfaces are explicitly described. Detailed analysis of the atomic mechanisms of the martensite transformation in NiTi using DFT revealed a new phase transformation (B19'-B19'') that sheds light on why the theoretically predicted ground state (BCO) is not observed experimentally and that the experimentally observed martensite phase (B19') can be stabilized by internal stresses. This finding is very important as the theoretically predicted ground state does not allow for shape memory in nanoscale NiTi samples. The size effects caused by the presence of free surfaces and the role of nanostructure in martensite transformation have been investigated in thin NiTi slabs. Surface energies of B2 phase (austenite), B19 (orthorhombic), B19' (martensite) and the body centered orthorhombic phase (BCO) are calculated using DFT. (110)B2 surfaces with in-plane atomic displacements stabilize the austenite phase with respect to B19' and BCO, thus

  3. Homochiral 3D metal-organic frameworks from chiral 1D rods: 6-way helical packing.

    PubMed

    Shin, Sung Min; Moon, Dohyun; Jeong, Kyung Seok; Kim, Jaheon; Thallapally, Praveen K; Jeong, Nakcheol

    2011-09-01

    The chiral 3D MOFs resulted from the packing of chiral 1D SBBs were studied. It was demonstrated that the final packing pattern is sensitively dependent on the dimension of SBBs. In addition, we were able to identify a new plywood-like network from ligand 2H(2) exhibiting an unprecedented six-way chiral helical packing motif, which extends the list of invariant rod packings. PMID:21773637

  4. Nanostructured FeRh in metallic and insulating films

    NASA Astrophysics Data System (ADS)

    Kaeswurm, B.; Jimenez-Villacorta, F.; Bennett, S. P.; Heiman, D.; Lewis, L. H.

    2014-03-01

    The formation of nanostructured FeRh in nonmagnetic metallic and insulating matrices is investigated and correlated with their structural and magnetic properties, with the goal of clarifying synthesis-structure-property relationships in confined geometries. Films containing FeRh with Al2O3 and Cu matrices were deposited on Si substrates using RF sputtering and then annealed up to 1073 K to form chemically-ordered FeRh particles with the B2 structure. FeRh nanostructures formed within the refractory Al2O3 matrix are rounded in shape and have a smaller average particle size of 60 nm, compared to the more irregular nanostructures obtained in the metallic Cu-FeRh sample with a larger average particle size ~150 nm. The different morphology of the two samples is explained in terms of the dissimilar properties of the matrices, and opens pathways for potential control of the fabrication of FeRh nanostructures. Keywords: FeRh, Magneto caloric effect, Magneto structural transition, Ferromagnetism.

  5. Optical activity of catalytic elements of hetero-metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Antosiewicz, Tomasz J.; Apell, S. Peter; Wadell, Carl; Langhammer, Christoph

    2015-05-01

    Interaction of light with metals in the form of surface plasmons is used in a wide range of applications in which the scattering decay channel is important. The absorption channel is usually thought of as unwanted and detrimental to the efficiency of the device. This is true in many applications, however, recent studies have shown that maximization of the decay channel of surface plasmons has potentially significant uses. One of these is the creation of electron-hole pairs or hot electrons which can be used for e.g. catalysis. Here, we study the optical properties of hetero-metallic nanostructures that enhance light interaction with the catalytic elements of the nanostructures. A hybridized LSPR that matches the spectral characteristic of the light source is excited. This LSPR through coupling between the plasmonic elements maximizes light absorption in the catalytic part of the nanostructure. Numerically calculated visible light absorption in the catalytic nanoparticles is enhanced 12-fold for large catalytic disks and by more 30 for small nanoparticles on the order of 5 nm. In experiments we measure a sizable increase in the absorption cross section when small palladium nanoparticles are coupled to a large silver resonator. These observations suggest that heterometallic nanostructures can enhance catalytic reaction rates.

  6. Adsorption of alkali, alkaline-earth, and 3d transition metal atoms on silicene

    NASA Astrophysics Data System (ADS)

    Sahin, H.; Peeters, F. M.

    2013-02-01

    The adsorption characteristics of alkali, alkaline-earth, and transition metal adatoms on silicene, a graphene-like monolayer structure of silicon are analyzed by means of first-principles calculations. In contrast to graphene, interaction between the metal atoms and the silicene surface is quite strong due to its highly reactive buckled hexagonal structure. In addition to structural properties, we also calculate the electronic band dispersion, net magnetic moment, charge transfer, work function, and dipole moment of the metal adsorbed silicene sheets. Alkali metals, Li, Na, and K, adsorb to hollow sites without any lattice distortion. As a consequence of the significant charge transfer from alkalis to silicene, metalization of silicene takes place. Trends directly related to atomic size, adsorption height, work function, and dipole moment of the silicene/alkali adatom system are also revealed. We found that the adsorption of alkaline-earth metals on silicene is entirely different from their adsorption on graphene. The adsorption of Be, Mg, and Ca turns silicene into a narrow gap semiconductor. Adsorption characteristics of eight transition metals Ti, V, Cr, Mn, Fe, Co, Mo, and W are also investigated. As a result of their partially occupied d orbital, transition metals show diverse structural, electronic, and magnetic properties. Upon the adsorption of transition metals, depending on the adatom type and atomic radius, the system can exhibit metal, half-metal, and semiconducting behavior. For all metal adsorbates, the direction of the charge transfer is from adsorbate to silicene, because of its high surface reactivity. Our results indicate that the reactive crystal structure of silicene provides a rich playground for functionalization at nanoscale.

  7. 3D Nanoporous Metal Phosphides toward High-Efficiency Electrochemical Hydrogen Production.

    PubMed

    Tan, Yongwen; Wang, Hao; Liu, Pan; Cheng, Chun; Zhu, Fan; Hirata, Akihiko; Chen, Mingwei

    2016-04-01

    Free-standing nanoporous metal phosphides are fabricated by a novel top-down method, by selectively leaching less-stable metal phases from rapidly solidified two-phase metal-phosphorus alloys. The phosphide phases with relatively high electrochemical stability are left as the skeletons of nanoporous structures. The resultant nanoporous phosphides with tunable pore size and porosity show superior catalytic activities toward electrochemical hydrogen production. PMID:26889914

  8. First-Principles Study of Electronic Structure and Hydrogen Adsorption of 3d Transition Metal Exposed Paddle Wheel Frameworks

    SciTech Connect

    Bak, J. H.; Le, V. D.; Kang, J.; Wei, S. H.; Kim, Y. H.

    2012-04-05

    Open-site paddle wheels, comprised of two transition metals bridged with four carboxylate ions, have been widely used for constructing metal-organic frameworks with large surface area and high binding energy sites. Using first-principles density functional theory calculations, we have investigated atomic and electronic structures of various 3d transition metal paddle wheels before and after metal exposure and their hydrogen adsorption properties at open metal sites. Notably, the hydrogen adsorption is impeded by covalent metal-metal bonds in early transition metal paddle wheels from Sc to Cr and by the strong ferromagnetic coupling of diatomic Mn and Fe in the paddle wheel configurations. A significantly enhanced H{sub 2} adsorption is predicted in the nonmagnetic Co{sub 2} and Zn{sub 2} paddle wheel with the binding energy of {approx}0.2 eV per H{sub 2}. We also propose the use of two-dimensional Co{sub 2} and Zn{sub 2} paddle wheel frameworks that could have strongly adsorbed dihydrogen up to 1.35 wt % for noncryogenic hydrogen storage applications.

  9. Highly efficient and controllable method to fabricate ultrafine metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Cai, Hongbing; Zhang, Kun; Yu, Xinxin; Pan, Nan; Tian, Yangchao; Luo, Yi; Wang, Xiaoping

    2015-11-01

    We report a highly efficient, controllable and scalable method to fabricate various ultrafine metallic nanostructures in this paper. The method starts with the negative poly-methyl-methacrylate (PMMA) resist pattern with line-width superior to 20 nm, which is obtained from overexposing of the conventionally positive PMMA under a low energy electron beam. The pattern is further shrunk to sub-10 nm line-width through reactive ion etching. Using the patter as a mask, we can fabricate various ultrafine metallic nanostructures with the line-width even less than 10 nm. This ion tailored mask lithography (ITML) method enriches the top-down fabrication strategy and provides potential opportunity for studying quantum effects in a variety of materials.

  10. Ultrathin Nanostructured Metals for Highly Transmissive Plasmonic Subtractive Color Filters

    PubMed Central

    Zeng, Beibei; Gao, Yongkang; Bartoli, Filbert J.

    2013-01-01

    Plasmonic color filters employing a single optically-thick nanostructured metal layer have recently generated considerable interest as an alternative to colorant-based color filtering technologies, due to their reliability, ease of fabrication, and high color tunability. However, their relatively low transmission efficiency (~30%) needs to be significantly improved for practical applications. The present work reports, for the first time, a novel plasmonic subtractive color filtering scheme that exploits the counter-intuitive phenomenon of extraordinary low transmission (ELT) through an ultrathin nanostructured metal film. This approach relies on a fundamentally different color filtering mechanism than that of existing plasmonic additive color filters, and achieves unusually high transmission efficiencies of 60 ~ 70% for simple architectures. Furthermore, owing to short-range interactions of surface plasmon polaritons at ELT resonances, our design offers high spatial resolution color filtering with compact pixel size close to the optical diffraction limit (~λ/2), creating solid applications ranging from imaging sensors to color displays. PMID:24100869

  11. Highly efficient and controllable method to fabricate ultrafine metallic nanostructures

    SciTech Connect

    Cai, Hongbing; Zhang, Kun; Pan, Nan E-mail: xpwang@ustc.edu.cn; Luo, Yi; Wang, Xiaoping E-mail: xpwang@ustc.edu.cn; Yu, Xinxin; Tian, Yangchao

    2015-11-15

    We report a highly efficient, controllable and scalable method to fabricate various ultrafine metallic nanostructures in this paper. The method starts with the negative poly-methyl-methacrylate (PMMA) resist pattern with line-width superior to 20 nm, which is obtained from overexposing of the conventionally positive PMMA under a low energy electron beam. The pattern is further shrunk to sub-10 nm line-width through reactive ion etching. Using the patter as a mask, we can fabricate various ultrafine metallic nanostructures with the line-width even less than 10 nm. This ion tailored mask lithography (ITML) method enriches the top-down fabrication strategy and provides potential opportunity for studying quantum effects in a variety of materials.

  12. MBE fabrication of self-assembled Si and metal nanostructures on Si surfaces

    SciTech Connect

    Galiana, Natalia; Martin, Pedro-Pablo; Munuera, Carmen; Varela del Arco, Maria; Soria, Federico; Ocal, Carmen; Ruiz, Ana; Alonso, Maria

    2006-01-01

    Two types of fairly regular distributions of Si nanostructures, of interest as templates to grow spatially controlled ensembles of metal (Co, Fe, Ag, etc.) nanostructures, are presented in this paper. Both of them are achieved by self-assembling processes during Si homoepitaxy. One corresponds to films grown by molecular beam epitaxy (MBE) on Si(0 0 1)-2 x 1 surfaces with low (<1 degree) miscut angles. In this case, arrays of 3D Si-islands displaying well defined pyramid-like shapes can be obtained, as evidenced by Scanning Force Microscopy (SFM) and Scanning Transmission Electron Microscopy (STEM). Such arrays exhibit strong similarities with those reported for Ge and SiGe islands on Si(0 0 1), and may thus serve as a simpler route to produce ordered distributions of metallic nanodots. On the other hand, on Si(1 1 1)-7 x 7 vicinal substrates misoriented 4 degrees toward the View the MathML source direction, step rearrangement during homoepitaxy permits to produce nanopatterned surfaces, the building-blocks of which are triangular (1 1 1) platforms, with lateral dimensions of hundreds of nanometers, bound by step bunches about 30 nm high. Furthermore, different Ag deposition experiments support this spontaneous patterning on Si(1 1 1) as a promising approach to achieve regular distributions of metallic nanocrystals with an overall homogeneity in sizes, shapes and spacing.

  13. MBE fabrication of self-assembled Si and metal nanostructures on Si surfaces

    NASA Astrophysics Data System (ADS)

    Galiana, Natalia; Martin, Pedro-Pablo; Munuera, Carmen; Varela, María; Soria, Federico; Ocal, Carmen; Ruiz, Ana; Alonso, María

    2006-09-01

    Two types of fairly regular distributions of Si nanostructures, of interest as templates to grow spatially controlled ensembles of metal (Co, Fe, Ag, etc.) nanostructures, are presented in this paper. Both of them are achieved by self-assembling processes during Si homoepitaxy. One corresponds to films grown by molecular beam epitaxy (MBE) on Si(0 0 1)-2 × 1 surfaces with low (<1°) miscut angles. In this case, arrays of 3D Si-islands displaying well defined pyramid-like shapes can be obtained, as evidenced by Scanning Force Microscopy (SFM) and Scanning Transmission Electron Microscopy (STEM). Such arrays exhibit strong similarities with those reported for Ge and SiGe islands on Si(0 0 1), and may thus serve as a simpler route to produce ordered distributions of metallic nanodots. On the other hand, on Si(1 1 1)-7 × 7 vicinal substrates misoriented 4° toward the [1 1 2¯] direction, step rearrangement during homoepitaxy permits to produce nanopatterned surfaces, the building-blocks of which are triangular (1 1 1) platforms, with lateral dimensions of hundreds of nanometers, bound by step bunches about 30 nm high. Furthermore, different Ag deposition experiments support this spontaneous patterning on Si(1 1 1) as a promising approach to achieve regular distributions of metallic nanocrystals with an overall homogeneity in sizes, shapes and spacing.

  14. Low Temperature Growth of Nanostructured Diamond Films on Metals

    NASA Technical Reports Server (NTRS)

    Baker, Paul A.; Catledge, Shane A.; Vohra, Yogesh K.

    2001-01-01

    The field of nanocrystalline diamond and tetrahedral amorphous carbon films has been the focus of intense experimental activity in the last few years for applications in field emission display devices, optical windows, and tribological coatings, The choice of substrate used in most studies has typically been silicon. For metals, however, the thermal expansion mismatch between the diamond film and substrate gives rise to thermal stress that often results in delamination of the film. To avoid this problem in conventional CVD deposition low substrate temperatures (less than 700 C) have been used, often with the incorporation of oxygen or carbon monoxide to the feedgas mixture. Conventionally grown CVD diamond films are also rough and would require post-deposition polishing for most applications. Therefore, there is an obvious need to develop techniques for deposition of well-adhered, smooth nano-structured diamond films on metals for various tribological applications. In our work, nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 C) for 30 minutes using a H2/CH4/N2 gas mixture in order to grow a thin (approx. 600 nm) nanostructured diamond layer and improve film adhesion. The remainder of the deposition involves growth at low temperature (less than 600 C) in a H2/CH4/O2 gas mixture. Laser reflectance Interferometry (LRI) pattern during growth of a nanostructured diamond film on Ti-6Al-4V alloy. The first 30 minutes are at a high temperature of 820 C and the rest of the film is grown at a low temperature of 580 T. The fringe pattern is observed till the very end due to extremely low surface roughness of 40 nm. The continuation of the smooth nanostructured diamond film growth during low temperature deposition is confirmed by in-situ laser reflectance interferometry and by post-deposition micro-Raman spectroscopy and surface profilometry. Similar experiments

  15. Ion beam synthesis and investigation of nanocomposite multiferroics based on barium titanate with 3 d metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Khalitov, N. I.; Lyadov, N. M.; Valeev, V. F.; Khaibullin, R. I.; Faizrakhmanov, I. A.; Dulov, E. N.; Tagirov, L. R.; Ibragimov, Sh. Z.; Prikhodko, K. E.; Roddatis, V. V.; Maksutoglu, M.; Kazan, S.; Mikailzade, F. A.

    2013-06-01

    Samples of nanocomposite multiferroics have been synthesized by implantation of Co+, Fe+, and Ni+ ions with an energy of 40 keV into ferroelectric barium titanate plates to doses in the range (0.5-1.5) × 1017 ions/cm2. It has been found that nanoparticles of metallic iron, cobalt, or nickel are formed in the barium titanate layer subjected to ion bombardment. With an increase in the implantation dose, the implanted samples sequentially exhibit superparamagnetic, soft magnetic, and, finally, strong ferromagnetic properties at room temperature. The average sizes of ion-synthesized 3 d-metal nanoparticles vary in the range from 5 to 10 nm depending on the implantation dose. Investigation of the orientation dependence of the magnetic hysteresis loops has demonstrated that the samples show a uniaxial ("easy plane") magnetic anisotropy typical of thin granular magnetic films. Ferromagnetic BaTiO3: 3 d metal samples are characterized by a significant shift of the ferromagnetic resonance signal in an external electric field, as well as by a large (in magnitude) magnetodielectric effect at room temperature. These results indicate that there is a strong magnetoelectric coupling between the ferroelectric barium titanate matrix and ion-synthesized nanoparticles of magnetic metals.

  16. Enhanced second harmonic generation from coupled asymmetric plasmonic metal nanostructures

    NASA Astrophysics Data System (ADS)

    Yildiz, Bilge Can; Emre Tasgin, Mehmet; Kurtulus Abak, Musa; Coskun, Sahin; Emrah Unalan, Husnu; Bek, Alpan

    2015-12-01

    We experimentally demonstrate that two coupled metal nanostructures (MNSs), a silver nanowire and bipyramid, can produce ∼30 times enhanced second harmonic generation compared to the particles alone. We develop a simple theoretical model, presenting the path interference effects in the nonlinear response of coupled MNSs. We show that the reason for such an enhancement can be the occurrence of a Fano resonance due to the coupling of the converter MNS to the long-lived mode of the attached MNS.

  17. Fatigue crack detection in metallic structures with Lamb waves and 3D laser vibrometry

    NASA Astrophysics Data System (ADS)

    Staszewski, W. J.; Lee, B. C.; Traynor, R.

    2007-03-01

    The paper presents the application of ultrasonic guided waves for fatigue crack detection in metallic structures. The study involves a simple fatigue test performed to introduce a crack into an aluminium plate. Lamb waves generated by a low-profile, surface-bonded piezoceramic transducer are sensed using a tri-axis, multi-position scanning laser vibrometer. The results demonstrate the potential of laser vibrometry for simple, rapid and robust detection of fatigue cracks in metallic structures. The method could be used in quality inspection and in-service maintenance of metallic structures in aerospace, civil and mechanical engineering industries.

  18. Composite lithium metal anode by melt infusion of lithium into a 3D conducting scaffold with lithiophilic coating.

    PubMed

    Liang, Zheng; Lin, Dingchang; Zhao, Jie; Lu, Zhenda; Liu, Yayuan; Liu, Chong; Lu, Yingying; Wang, Haotian; Yan, Kai; Tao, Xinyong; Cui, Yi

    2016-03-15

    Lithium metal-based battery is considered one of the best energy storage systems due to its high theoretical capacity and lowest anode potential of all. However, dendritic growth and virtually relative infinity volume change during long-term cycling often lead to severe safety hazards and catastrophic failure. Here, a stable lithium-scaffold composite electrode is developed by lithium melt infusion into a 3D porous carbon matrix with "lithiophilic" coating. Lithium is uniformly entrapped on the matrix surface and in the 3D structure. The resulting composite electrode possesses a high conductive surface area and excellent structural stability upon galvanostatic cycling. We showed stable cycling of this composite electrode with small Li plating/stripping overpotential (<90 mV) at a high current density of 3 mA/cm(2) over 80 cycles. PMID:26929378

  19. 3D hybrid-porous carbon derived from carbonization of metal organic frameworks for high performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Bao, Weizhai; Mondal, Anjon Kumar; Xu, Jing; Wang, Chengyin; Su, Dawei; Wang, Guoxiu

    2016-09-01

    We report a rational design and synthesis of 3D hybrid-porous carbon with a hierarchical pore architecture for high performance supercapacitors. It contains micropores (<2 nm diameter) and mesopores (2-4 nm), derived from carbonization of unique porous metal organic frameworks (MOFs). Owning to the synergistic effect of micropores and mesopores, the hybrid-porous carbon has exceptionally high ion-accessible surface area and low ion diffusion resistance, which is desired for supercapacitor applications. When applied as electrode materials in supercapacitors, 3D hybrid-porous carbon demonstrates a specific capacitance of 332 F g-1 at a constant charge/discharge current of 500 mA g-1. The supercapacitors can endure more than 10,000 cycles without degradation of capacitance.

  20. Highly efficient nonprecious metal catalysts towards oxygen reduction reaction based on three-dimensional porous carbon nanostructures.

    PubMed

    Zhu, Chengzhou; Li, He; Fu, Shaofang; Du, Dan; Lin, Yuehe

    2016-02-01

    Developing a low cost, highly active, durable cathode towards an oxygen reduction reaction (ORR) is one of the high-priority research directions for commercialization of low-temperature polymer electrolyte membrane fuel cells (PEMFCs). However, the electrochemical performance of PEMFCs is still hindered by the high cost and insufficient durability of the traditional Pt-based cathode catalysts. Under these circumstances, the search for efficient alternatives to replace Pt for constructing highly efficient nonprecious metal catalysts (NPMCs) has been growing intensively and has received great interest. Combining with the compositional effects, the accurate design of NPMCs with 3D porous nanostructures plays a significant role in further enhancing ORR performance. These 3D porous architectures are able to provide higher specific surface areas and larger pore volumes, not only maximizing the availability of electron transfer within the nanosized electrocatalyst surface area but also providing better mass transport of reactants to the electrocatalyst. In this Tutorial Review, we focus on the rational design and synthesis of different 3D porous carbon-based nanomaterials, such as heteroatom-doped carbon, metal-nitrogen-carbon nanostructures and a series of carbon/nonprecious metal-based hybrids. More importantly, their enhanced ORR performances are also demonstrated by virtue of their favorably porous morphologies and compositional effects. Finally, the future trends and perspectives for the highly efficient porous NPMCs regarding the material design are discussed, with an emphasis on substantial development of advanced carbon-based NPMCs for ORR in the near future. PMID:26658546

  1. Modelling of transport phenomena in 3D GMAW of thick metals with V groove

    NASA Astrophysics Data System (ADS)

    Hu, J.; Tsai, H. L.

    2008-03-01

    This paper analyses the dynamic process of groove filling and the resulting weld pool fluid flow in gas metal arc welding of thick metals with V groove. Filler droplets carrying mass, momentum, thermal energy and sulfur species are periodically impinged onto the workpiece. The complex transport phenomena in the weld pool, caused by the combined effect of droplet impingement, gravity, electromagnetic force, surface tension and plasma arc pressure, were investigated to determine the transient weld pool shape and distributions of velocity, temperature and sulfur species in the weld pool. It was found that the groove provides a channel which can smooth the flow in the weld pool, leading to poor mixing between the filler metal and the base metal.

  2. Engineering Hybrid Metallic Nanostructures Using a Single Domain of Block Copolymer Templates.

    PubMed

    Liu, Zhicheng; Chang, Tongxin; Huang, Haiying; He, Tianbai

    2015-11-25

    Building complex nanostructures using a simple patterned template is challenging in material science and nanotechnology. In the present work, three different strategies have been exploited for the successful fabrication of hybrid dots-on-wire metallic nanostructures through combining an in-situ method with an ex-situ method. Basically, plasma etching was applied to generate a metallic wire-like nanostructure, and preformed nanoparticles could be placed through multiple means before or after the formation of the wire-like nanostructure. Various monometallic and bimetallic nanostructures have been obtained by utilizing only one functional domain of block copolymer templates. In these cases, full utilization of the functional domain or introduction of the molecular linker is critical to engineering hybrid metallic nanostructures. Other complex and multifunctional hybrid nanostructures can be developed via these strategies similarly, and these nanostructures are promising for useful applications such as optics and surface-enhanced Raman spectroscopy (SERS). PMID:26517409

  3. Structural, magnetic and conduction properties of 3d-metal monoatomic wires

    NASA Astrophysics Data System (ADS)

    García-Fuente, A.; Daul, C.

    2014-04-01

    From density functional theory calculations, we study the structure, magnetism and conduction properties of monoatomic wires made of all the 3d elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu). Wires with equidistant and alternating bond lengths are considered. Both magnetism and structure are found to play an important role for the conduction properties of the wires. Ferromagnetic wires are found to present a spin filtering effect which is not directly related with the magnitude of their magnetic moment. On the other hand, the main effect of bond length alternation is to partially destroy the transmission around the Fermi level, especially from the d bands. Ni wires are found to present particularly interesting spin filtering properties, meanwhile Cr wires present promising magnetoresistive effects.

  4. Metal-mesh based transparent electrode on a 3-D curved surface by electrohydrodynamic jet printing

    NASA Astrophysics Data System (ADS)

    Seong, Baekhoon; Yoo, Hyunwoong; Dat Nguyen, Vu; Jang, Yonghee; Ryu, Changkook; Byun, Doyoung

    2014-09-01

    Invisible Ag mesh transparent electrodes (TEs), with a width of 7 μm, were prepared on a curved glass surface by electrohydrodynamic (EHD) jet printing. With a 100 μm pitch, the EHD jet printed the Ag mesh on the convex glass which had a sheet resistance of 1.49 Ω/□. The printing speed was 30 cm s-1 using Ag ink, which had a 10 000 cPs viscosity and a 70 wt% Ag nanoparticle concentration. We further showed the performance of a 3-D transparent heater using the Ag mesh transparent electrode. The EHD jet printed an invisible Ag grid transparent electrode with good electrical and optical properties with promising applications on printed optoelectronic devices.

  5. Fracture Resistance of Non-Metallic Molar Crowns Manufactured with CEREC 3D

    NASA Astrophysics Data System (ADS)

    Madani, Dalia A.

    Objectives. To compare fracture strength and fatigue resistance of ceramic (ProCAD, Ivoclar-Vivadent) (C) and resin composite (Paradigm MZ100, 3M/ ESPE) (R) crowns made with CEREC-3D. Methods. A prepared ivorine molar tooth was duplicated to produce 40 identical prepared specimens made of epoxy resin (Viade). Twenty (C) crowns and 20 (R) were cemented to their dies using resin cement. Ten of each group were subjected to compressive loading to fracture. The remaining 10 of each group were subjected to mechanical cyclic loading for 500,000 cycles. The survivors were subjected to compressive loading to fracture. Results. No significant difference in mean fracture load was found between the two materials. However, only 30% of the (C) crowns vs. 100% of the (R) crowns survived the cyclic loading test. Conclusions. (R) crowns demonstrated higher fatigue Resistance than (C) crowns in-vitro and might better resist cracking in-vivo.

  6. Nanostructured target fabrication with metal and semiconductor nanoparticles

    NASA Astrophysics Data System (ADS)

    Barberio, M.; Antici, P.

    2015-10-01

    The development of ultra-intense high-energy (≫1 J) short (<1 ps) laser pulses in the last decade has enabled the acceleration of high-energy short-pulse proton beams. A key parameter for enhancing the acceleration regime is the laser-to-target absorption, which heavily depends on the target structure and material. In this work, we present the realization of a nanostructured target with a sub-laser wavelength nano-layer in the front surface as a possible candidate for improving the absorption. The nanostructured film was realized by a simpler and cheaper method than using conventional lithographic techniques: A colloidal solution of metallic or semiconductor nanoparticles (NPs) was produced by laser ablation and, after a heating and sonication process, was spray-dried on the front surface of an aluminum target. The obtained nanostructured film with a thickness of 1 μm appears, at morphological and chemical analysis, uniformly nanostructured and distributed on the target surface without the presence of oxides or external contaminants. Finally, the size of the NPs can be tuned from tens to hundreds of nanometers simply by varying the growth parameters (i.e., irradiation time, fluence, and laser beam energy).

  7. A comparative DFT study of the catalytic activity of the 3d transition metal sulphides surfaces

    SciTech Connect

    Gomez-Balderas, R.; Oviedo-Roa, R; Martinez-Magadan, J M.; Amador, C.; Dixon, David A. )

    2002-10-10

    The catalytic activity of the first transition metal series sulphides for hydrodesulfurization (HDS) reactions exhibits a particular behaviour when analysed as a function of the metal position in the Periodic Table. This work reports a comparative study of the electronic structure of the bulk and of the (0 0 1) metal surface (assumed to be the reactive surface) for the Sc-Zn monosulphides. The systems were modeled using the NiAs prototype crystal structure for the bulk and by applying the supercell model with seven atomic layers for (0 0 1) surfaces. The electronic structure of closed-packed solids code based on the density-functional theory and adopting the muffin-tin approximation to the potential was employed in the calculations of the electronic properties. For the Co and Ni sulphides, the density of states (DOS) variations between the metal atom present in the bulk and the ones exposed at the surface show that at the surface, there exists a higher DOS in the occupied states region just below the Fermi level. This feature might indicate a good performance of these two metal sulphides substrates in the HDS reactions favouring a donation, back-donation mechanism. In contrast, the DOS at the surface of Mn is increased in the unoccupied states region, just above the Fermi level. This suggests the possibility of a strong interaction with charge dontating sulphur adsorbate atoms poisoning the active substrate surface.

  8. Synthesis, characterization and antifungal activities of 3d-transition metal complexes of 1-acetylpiperazinyldithioc arbamate, M(acpdtc) 2

    NASA Astrophysics Data System (ADS)

    Mohammad, Ali; Varshney, Charu; Nami, Shahab A. A.

    2009-07-01

    A series of mononuclear 3d-transition metal complexes of the type M(acpdtc) 2 have been synthesized (where acpdtc = 1-acetylpiperazinyldithiocarbamate, M = Mn(II), Fe(II), Co(II), Ni(II) and Cu(II)). The ligand and its complexes have been characterized by micro analysis (CHNS), TG/DSC, FT-IR, UV-vis, 1H NMR, magnetic susceptibility and conductance measurements. On the basis IR spectroscopy a symmetrical bidentate coordination has been observed for the 1-acetylpiperazinyldithiocarbamate moiety in all the complexes. On the basis of UV-vis spectra and magnetic susceptibility measurement a square-planar geometry has been proposed for the Ni(II) and Cu(II) complexes while the other complexes have been found to acquire a distorted-tetrahedral structure. The thermogravimetric and differential scanning calorimetric profile of the ligand indicates a two-step decomposition pattern while the complexes exhibit a three-stage thermogram forming metal sulfide as the eventual end product. The molar conductivity data of 1 mM solution in DMSO of the complexes is in close accord to their non-electrolytic behaviour. The ligand and its 3d-transition metal complexes have also been tested for their antifungicidal activity by agar well diffusion method using Fusarium sp. and Sclerotina sp. The maximum activity has been observed in case of Mn(II) and Fe(II) complexes.

  9. A 3D analysis of the metal distribution in the compact group of galaxies HCG 31

    NASA Astrophysics Data System (ADS)

    Torres-Flores, Sergio; Mendes de Oliveira, Claudia; Alfaro-Cuello, Mayte; Rodrigo Carrasco, Eleazar; de Mello, Duilia; Amram, Philippe

    2015-02-01

    We present new Gemini/GMOS integral field unit observations of the central region of the merging compact group of galaxies HCG 31. Using this data set, we derive the oxygen abundances for the merging galaxies HCG 31A and HCG 31C. We found a smooth metallicity gradient between the nuclei of these galaxies, suggesting a mixing of metals between these objects. These results are confirmed by high-resolution Fabry-Perot data, from which we infer that gas is flowing between HCG 31A and HCG 31C.

  10. Biopolymer nanostructures induced by plasma irradiation and metal sputtering

    NASA Astrophysics Data System (ADS)

    Slepička, P.; Juřík, P.; Malinský, P.; Macková, A.; Kasálková, N. Slepičková; Švorčík, V.

    2014-08-01

    Modification based on polymer surface exposure to plasma treatment exhibits an easy and cheap technique for polymer surface nanostructuring. The influence of argon plasma treatment on biopolymer poly(L-lactide acid (PLLA) will be presented in this paper. The combination of Ar+ ion irradiation, consequent sputter metallization (platinum) and thermal annealing of polymer surface will be summarized. The surface morphology was studied using atomic force microscopy. The Rutherford Backscattering Spectroscopy and X-ray Photoelectron Spectroscopy were used as analytical methods. The combination of plasma treatment with consequent thermal annealing and/or metal sputtering led to the change of surface morphology and its elemental ratio. The surface roughness and composition has been strongly influenced by the modification parameters and metal layer thickness. By plasma treatment of polymer surface combined with consequent annealing or metal deposition can be prepared materials applicable both in tissue engineering as cell carriers, but also in integrated circuit manufacturing.

  11. Study on the electronic structure and Fermi surface of 3d-transition-metal disilisides CoSi2

    NASA Astrophysics Data System (ADS)

    Hamid, A. S.

    2012-09-01

    We have investigated the electronic structure, the momentum density distribution ρ( p), and the Fermi surface FS of single crystals of the Pyrite-type 3d-transition-metal disilisides CoSi2. The band structure calculations, the density of states DOS, and the FS, in vicinity of Fermi level, have been carried out using the full-potential linearized augmented plane wave FP-LAPW method within generalized gradient approximation GGA for exchange and correlation potential. The measurements have been performed via the 2D angular correlation of annihilation radiation ACAR experiments. ρ( p) has been reconstructed by using the Fourier transformation technique. The FS has been reconstructed within the first Brillion zone BZ through the Locks, Crisp, and West LCW folding procedures. The analysis confirmed that Si 3 sp states hybrid with both Co 3 d- t 2 g and Co 3 d- e g states around Γ and X points, respectively. The dimensions of the FS of CoSi2 have been compared to the present calculations as well as to the earlier results.

  12. 3d-transition metal induced enhancement of molecular hydrogen adsorption on Mg(0001) surface: An Ab-initio study

    NASA Astrophysics Data System (ADS)

    Banerjee, Paramita; Das, G. P.

    2016-05-01

    In our effort to do first principles design of suitable materials for hydrogen storage, we have explored the interaction characteristics of a hydrogen molecule with pure as well as a 3d-transition metal (TM) atom doped Mg(0001) surface using density functional theory (DFT) based approach. Doping of a 3d-TM atom by creating a vacancy on the top most layer of Mg(0001) surface, enhances the molecular hydrogen adsorption efficiency of this surface by ~ 6 times. The TM atom gains some charge from the defected site of the Mg(0001) surface, becomes anionic and adsorbs the hydrogen molecule via Anti Kubas-type interaction. The interaction energy of this H2 molecule, including van der Waals dispersion correction, turns out to be ~ 0.4 eV, which falls in the right energy window between physisorption and chemisorption. On full coverage of this 3d-TM atom doped Mg(0001) surface with hydrogen molecules, the gravimetric density of hydrogen has been estimated to be ~ 5.6 wt %, thereby satisfying the criteria set by the department of energy (DOE) for efficient hydrogen storage.

  13. Ferromagnetic interactions between transition-metal impurities in topological and 3D Dirac semimetals

    NASA Astrophysics Data System (ADS)

    Dietl, Tomasz

    The magnitude of ferromagnetic coupling driven by inter-band (Bloembergen-Rowland - BR) and intra-band (Ruderman-Kittel-Kasuya-Yoshida - RKKY) spin polarization is evaluated within kp theory for topological semimetals Hg1-xMnxTe and Hg1-xMnxSe as well as for 3D Dirac semimetal (Cd1-xMnx)3As2. In these systems Mn2+ ions do not introduce any carriers. Since, however, both conduction and valence bands are built from anion p-type wave functions, hybridization of Mn d levels with neighboring anion p states leads to spin-dependent p - d coupling of both electrons and holes to localized Mn spins, resulting in sizable inter-band spin polarization and, thus in large BR interactions. We demonstrate that this ferromagnetic coupling, together with antiferromagnetic superexchange, elucidate a specific dependence of spin-glass freezing temperature on x, determined experimentally for these systems. Furthermore, by employing a multi-orbital tight-binding method, we find that superexchange becomes ferromagnetic when Mn is replaced by Cr or V. Since Cr should act as an isoelectronic impurity in HgTe, this opens a road for realization of ferromagnetic topological insulators based on (Hg,Cr)Te.

  14. Quantum electrodynamics and plasmonic resonance of metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Zhang, Mingliang; Xiang, Hongping; Zhang, Xu; Lu, Gang

    2016-04-01

    Plasmonic resonance of a metallic nanostructure results from coherent motion of its conduction electrons driven by incident light. At the resonance, the induced dipole in the nanostructure is proportional to the number of the conduction electrons, hence 107 times larger than that in an atom. The interaction energy between the induced dipole and fluctuating virtual field of the incident light can reach a few tenths of an eV. Therefore, the classical electromagnetism dominating the field may become inadequate. We propose that quantum electrodynamics (QED) may be used as a fundamental theory to describe the interaction between the virtual field and the oscillating electrons. Based on QED, we derive analytic expressions for the plasmon resonant frequency, which depends on three easily accessible material parameters. The analytic theory reproduces very well the experimental data, and can be used in rational design of materials for plasmonic applications.

  15. Deposition of carbon nanostructures on metal substrates at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Dimitrov, Zh; Nikovski, M.; Kiss'ovski, Zh

    2016-03-01

    The microwave-plasma-enhanced CVD of carbon nanostructures at atmospheric pressure allows shorter deposition times and reduces the complexity of the experimental set-up. In our study, the substrate temperature was varied in a wide range (300 – 700 C) using microwave plasma heating, as well as an additional heater. The distance between the substrate and the plasma flame was also varied in order to establish the conditions for an efficient deposition process, the latter being carried out at specific argon/hydrogen/methane gas mixtures. Optical measurements of the plasma flame spectrum were conducted to obtain the gas temperature and the plasma density and to analyze the existence of reactive species. The carbon nanostructures deposited on the metal samples were investigated by SEM. The relation between the morphology and the gas-discharge conditions is discussed.

  16. Quantum electrodynamics and plasmonic resonance of metallic nanostructures.

    PubMed

    Zhang, Mingliang; Xiang, Hongping; Zhang, Xu; Lu, Gang

    2016-04-20

    Plasmonic resonance of a metallic nanostructure results from coherent motion of its conduction electrons driven by incident light. At the resonance, the induced dipole in the nanostructure is proportional to the number of the conduction electrons, hence 10(7) times larger than that in an atom. The interaction energy between the induced dipole and fluctuating virtual field of the incident light can reach a few tenths of an eV. Therefore, the classical electromagnetism dominating the field may become inadequate. We propose that quantum electrodynamics (QED) may be used as a fundamental theory to describe the interaction between the virtual field and the oscillating electrons. Based on QED, we derive analytic expressions for the plasmon resonant frequency, which depends on three easily accessible material parameters. The analytic theory reproduces very well the experimental data, and can be used in rational design of materials for plasmonic applications. PMID:26987436

  17. Chiral structures and tunable magnetic moments in 3d transition metal doped Pt6 clusters

    NASA Astrophysics Data System (ADS)

    Zhang, Xiu-Rong; Yang, Xing; Ding, Xun-Lei

    2012-09-01

    The structural, electronic, and magnetic properties of transition metal doped platinum clusters MPt6 (M=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) are systematically studied by using the relativistic all-electron density functional theory with the generalized gradient approximation. Most of the doped clusters show larger binding energies than the pure Pt7 cluster, which indicates that the doping of the transition metal atom can stabilize the pure platinum cluster. The results of the highest occupied molecular orbital (HOMO)—lowest unoccupied molecular orbital (LUMO) gaps suggest that the doped clusters can have higher chemical activities than the pure Pt7 cluster. The magnetism calculations demonstrate that the variation range of the magnetic moments of the MPt6 clusters is from 0 μB to 7 μB, revealing that the MPt6 clusters have potential utility in designing new spintronic nanomaterials with tunable magnetic properties.

  18. 3D porous metal-organic framework as an efficient electrocatalyst for nonenzymatic sensing application.

    PubMed

    Zhang, Daojun; Zhang, Jingchao; Zhang, Renchun; Shi, Huaizhong; Guo, Yuanyuan; Guo, Xiuli; Li, Sujuan; Yuan, Baiqing

    2015-11-01

    Novel electroactive materials with high surface area and stability have great potential for electrochemical sensor. Herein, we demonstrate the exploitation of a porous Cu-based metal-organic framework (Cu-MOF) with large pore size as nonenzymatic sensors for the electrochemical determination of hydrogen peroxide (H2O2) and glucose. The Cu-MOF shows high stability even in NaOH solution. The as-prepared Cu-MOF modified carbon paste electrode (CPE) presents a well-behaved redox event from electroactive metal centers in the MOF at the physiological pH which can be utilized to catalyze the electroreduction of H2O2. It also exhibited excellent electrocatalytic activity towards the oxidation of glucose in alkaline solution. The results showed that the nonenzymatic sensors based on the Cu-MOF display excellent analytical performances, which make it a promising candidate in electrochemical sensor. PMID:26452944

  19. 3-D Modelling of Electromagnetic, Thermal, Mechanical and Metallurgical Couplings in Metal Forming Processes

    SciTech Connect

    Chenot, Jean-Loup; Bay, Francois

    2007-04-07

    The different stages of metal forming processes often involve - beyond the mechanical deformations processes - other physical coupled problems, such as heat transfer, electromagnetism or metallurgy. The purpose of this paper is to focus on problems involving electromagnetic couplings. After a brief recall on electromagnetic modeling, we shall then focus on induction heating processes and present some results regarding heat transfer, as well as mechanical couplings. A case showing coupling for metallurgic microstructure evolution will conclude this paper.

  20. 3D Behavior of Schottky Barriers of 2D Transition-Metal Dichalcogenides.

    PubMed

    Guo, Yuzheng; Liu, Dameng; Robertson, John

    2015-11-25

    The transition metal dichalcogenides (TMDs) are two-dimensional layered solids with van der Waals bonding between layers. We calculate their Schottky barrier heights (SBHs) using supercell models and density functional theory. It is found that the SBHs without defects are quite strongly pinned, with a pinning factor S of about S = 0.3, a similar value for both top and edge contact geometries. This arises because there is direct bonding between the contact metal atoms and the TMD chalcogen atoms, for both top and edge contact geometries, despite the weak interlayer bonding in the isolated materials. The Schottky barriers largely follow the metal induced gap state (MIGS) model, like those of three-dimensional semiconductors, despite the bonding in the TMDs being largely constrained within the layers. The pinning energies are found to be lower in the gap for edge contact geometries than for top contact geometries, which might be used to obtain p-type contacts on MoS2. PMID:26523332

  1. Micro-electrical discharge machining of 3D micro-molds from Pd40Cu30P20Ni10 metallic glass by using laminated 3D micro-electrodes

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Wu, Xiao-yu; Ma, Jiang; Liang, Xiong; Lei, Jian-guo; Wu, Bo; Ruan, Shuang-chen; Wang, Zhen-long

    2016-03-01

    For obtaining 3D micro-molds with better surface quality (slight ridges) and mechanical properties, in this paper 3D micro-electrodes were fabricated and applied to micro-electrical discharge machining (micro-EDM) to process Pd40Cu30P20Ni10 metallic glass. First, 100 μm-thick Cu foil was cut to obtain multilayer 2D micro-structures and these were connected to fit 3D micro-electrodes (with feature sizes of less than 1 mm). Second, under the voltage of 80 V, pulse frequency of 0.2MHZ, pulse width of 800 ns and pulse interval of 4200 ns, the 3D micro-electrodes were applied to micro-EDM for processing Pd40Cu30P20Ni10 metallic glass. The 3D micro-molds with feature within 1 mm were obtained. Third, scanning electron microscope, energy dispersive spectroscopy and x-ray diffraction analysis were carried out on the processed results. The analysis results indicate that with an increase in the depth of micro-EDM, carbon on the processed surface gradually increased from 0.5% to 5.8%, and the processed surface contained new phases (Ni12P5 and Cu3P).

  2. A 3D metal artifact correction method in cone-beam CT bone imaging by using an implant image library

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Ning, Ruola; Conover, David

    2008-03-01

    Cone-beam CT (CBCT) technique has been used by orthopedists to monitor bone graft growth after orthopedic surgery. In order to correct severe metal artifacts in reconstructed images caused by metal implants used in bone grafting, a three-dimensional metal artifact correction method has been previously proposed. The implants' mathematic boundaries were generated to help to segment metal from reconstructed images. The segmented metal implants were forward-projected onto the detector to create metal-only projections to compensate for beam-hardening effect. This method was proved effective with the metal implants of regular shape which can be simulated by simple 3D primitives, such as cuboid, cylinder and cone. But for metal implants of arbitrary shape, their boundaries are difficult to define mathematically. To solve this problem, this paper proposed a method by setting up an implant image library and using the implants' a priori shape information from the library during the artifact correction. The implants were acquired and scanned before the surgery and their a priori information were stored in a library. During the artifact correction, the library was called to provide the shape information of the implants to help to do the implant segmentation. The segmented implants were forward-projected onto the detector to generate implant-only projections by a cone-beam forward-projection technique. Beam-hardening effect in the original projections was then compensated by high polynomial orders of implant projections. Finally, the corrected projections were back-projected to produce artifacts-reduced images. Both phantom studies and patient studies were conducted to test this correction method. Results from both studies show the artifacts have been greatly reduced and the accuracy of bone volume measurement has been increased.

  3. Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite.

    PubMed

    Zhang, Wei; Bodey, Andrew J; Sui, Tan; Kockelmann, Winfried; Rau, Christoph; Korsunsky, Alexander M; Mi, Jiawei

    2016-01-01

    Bulk metallic glass matrix composites (BMGMCs) are a new class of metal alloys which have significantly increased ductility and impact toughness, resulting from the ductile crystalline phases distributed uniformly within the amorphous matrix. However, the 3D structures and their morphologies of such composite at nano and micrometre scale have never been reported before. We have used high density electric currents to thermally shock a Zr-Ti based BMGMC to different temperatures, and used X-ray microtomography, FIB-SEM nanotomography and neutron diffraction to reveal the morphologies, compositions, volume fractions and thermal stabilities of the nano and microstructures. Understanding of these is essential for optimizing the design of BMGMCs and developing viable manufacturing methods. PMID:26725519

  4. Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

    PubMed Central

    Zhang, Wei; Bodey, Andrew J.; Sui, Tan; Kockelmann, Winfried; Rau, Christoph; Korsunsky, Alexander M.; Mi, Jiawei

    2016-01-01

    Bulk metallic glass matrix composites (BMGMCs) are a new class of metal alloys which have significantly increased ductility and impact toughness, resulting from the ductile crystalline phases distributed uniformly within the amorphous matrix. However, the 3D structures and their morphologies of such composite at nano and micrometre scale have never been reported before. We have used high density electric currents to thermally shock a Zr-Ti based BMGMC to different temperatures, and used X-ray microtomography, FIB-SEM nanotomography and neutron diffraction to reveal the morphologies, compositions, volume fractions and thermal stabilities of the nano and microstructures. Understanding of these is essential for optimizing the design of BMGMCs and developing viable manufacturing methods. PMID:26725519

  5. Method and apparatus for ion sequestration and a nanostructured metal phosphate

    DOEpatents

    Mattigod, Shas V.; Fryxell, Glen E.; Li, Xiaohong; Parker, Kent E.; Wellman, Dawn M.

    2010-04-06

    A nanostructured substance, a process for sequestration of ionic waste, and an ion-sequestration apparatus are disclosed in the specification. The nanostructured substance can comprise a Lewis acid transition metal bound to a phosphate, wherein the phosphate comprises a primary structural component of the substance and the Lewis acid transition metal is a reducing agent. The nanostructured substance has a Brunner-Emmet-Teller (BET) surface area greater than or equal to approximately 100 m.sup.2/g, and a distribution coefficient for an analyte, K.sub.d, greater than or equal to approximately 5000 ml/g. The process can comprise contacting a fluid and a nanostructured metal phosphate. The apparatus can comprise a vessel and a nanostructured metal phosphate. The vessel defines a volume wherein a fluid contacts the nanostructured metal phosphate.

  6. Investigation of molten metal droplet deposition and solidification for 3D printing techniques

    NASA Astrophysics Data System (ADS)

    Wang, Chien-Hsun; Tsai, Ho-Lin; Wu, Yu-Che; Hwang, Weng-Sing

    2016-09-01

    This study investigated the transient transport phenomenon during the pile up of molten lead-free solder via the inkjet printing method. With regard to the droplet impact velocity, the distance from nozzle to substrate can be controlled by using the pulse voltage and distance control apparatus. A high-speed digital camera was used to record the solder impact and examine the accuracy of the pile up. These impact conditions correspond to We  =  2.1–15.1 and Oh  =  5.4  ×  10‑3–3.8  ×  10‑3. The effects of impact velocity and relative distance between two types of molten droplets on the shape of the impact mode are examined. The results show that the optimal parameters of the distance from nozzle to substrate and the spreading factor in this experiment are 0.5 mm and 1.33. The diameter, volume and velocity of the inkjet solder droplet are around 37–65 μm, 25–144 picoliters, and 2.0–3.7 m s‑1, respectively. The vertical and inclined column structures of molten lead-free solder can be fabricated using piezoelectric ink-jet printing systems. The end-shapes of the 3D micro structure have been found to be dependent upon the distance from nozzle to substrate and the impact velocity of the molten lead-free solder droplet.

  7. Densely Packed Lanthanide Cubane Based 3D Metal-Organic Frameworks for Efficient Magnetic Refrigeration and Slow Magnetic Relaxation.

    PubMed

    Biswas, Soumava; Mondal, Amit Kumar; Konar, Sanjit

    2016-03-01

    Two isostructural densely packed squarato-bridged lanthanide-based 3D metal-organic frameworks (MOFs) [Ln5(μ3-OH)5(μ3-O)(CO3)2(HCO2)2(C4O4)(H2O)2] [Ln = Gd (1) and Dy (2)] show giant cryogenic magnetic refrigeration (for 1) and slow magnetic relaxation (for 2). The structural analyses reveal the presence of a self-assembled crown-shaped building unit with a cubane-based rectangular moiety that leads to a special array of metal centers in 3D space in the complexes. Magnetic investigations confirm that complex 1 exhibits one of the largest cryogenic magnetocaloric effects among the molecular magnetic refrigerant materials reported so far (-ΔSm = 64.0 J kg(-1) K(-1) for ΔH = 9 T at 3 K). The cryogenic cooling effect (of 1) is also quite comparable with that of the commercially used magnetic refrigerant gadolinium-gallium garnet, whereas for complex 2, slow relaxation of magnetization was observed below 10 K. PMID:26881286

  8. Microwave and camera sensor fusion for the shape extraction of metallic 3D space objects

    NASA Technical Reports Server (NTRS)

    Shaw, Scott W.; Defigueiredo, Rui J. P.; Krishen, Kumar

    1989-01-01

    The vacuum of space presents special problems for optical image sensors. Metallic objects in this environment can produce intense specular reflections and deep shadows. By combining the polarized RCS with an incomplete camera image, it has become possible to better determine the shape of some simple three-dimensional objects. The radar data are used in an iterative procedure that generates successive approximations to the target shape by minimizing the error between computed scattering cross-sections and the observed radar returns. Favorable results have been obtained for simulations and experiments reconstructing plates, ellipsoids, and arbitrary surfaces.

  9. 3D dislocation dynamics: stress-strain behavior and hardening mechanisms in FCC and BCC metals

    SciTech Connect

    Hirth, J P; Rhee, M; Zhib, H M; de la Rubia, T D

    1999-02-19

    A dislocation dynamics (DD) model for plastic deformation, connecting the macroscopic mechanical properties to basic physical laws governing dislocation mobility and related interaction mechanisms, has been under development. In this model there is a set of critical reactions that determine the overall results of the simulations, such as the stress-strain curve. These reactions are, annihilation, formation of jogs, junctions, and dipoles, and cross-slip. In this paper we discuss these reactions and the manner in which they influence the simulated stress- strain behavior in fcc and bcc metals. In particular, we examine the formation (zipping) and strength of dipoles and junctions, and effect of jogs, using the dislocation dynamics model. We show that the strengths (unzipping) of these reactions for various configurations can be determined by direct evaluation of the elastic interactions. Next, we investigate the phenomenon of hardening in metals subjected to cascade damage dislocations. The microstructure investigated consists of small dislocation loops decorating the mobile dislocations. Preliminary results reveal that these loops act as hardening agents, trapping the dislocations and resulting in increased hardening.

  10. Computer Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2004-01-01

    In friction stir welding, a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. This solid-state technique has been successfully used in the joining of materials that are difficult to fusion weld such as aluminum alloys. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and thus tracks the aluminum deformation flow paths in a unique 3-dimensional manner. CT scanning is a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  11. Core-shell and segmented polymer-metal composite nanostructures.

    PubMed

    Lahav, Michal; Weiss, Emily A; Xu, Qiaobing; Whitesides, George M

    2006-09-01

    Composite nanostructures (approximately 200 nm wide and several micrometers long) of metal and polyaniline (PANI) in two new variations of core-shell (PANI-Au) and segmented (Au-PANI and Ni-Au-PANI) architectures were fabricated electrochemically within anodized aluminum oxide (AAO) membranes. Control over the structure of these composites (including the length of the gold shells in the core-shell structures) was accomplished by adjusting the time and rate of electrodeposition and the pH of the solution from which the materials were grown. Exposure of the core-shell structures to oxygen plasma removed the PANI and yielded aligned gold nanotubes. In the segmented structures, a self-assembled monolayer (SAM) of thioaniline nucleated the growth of PANI on top of metal nanorods and acted as an adhesion layer between the metal and PANI components. PMID:16968046

  12. Metal sulfide and rare-earth phosphate nanostructures and methods of making same

    DOEpatents

    Wong, Stanislaus; Zhang, Fen

    2016-06-28

    The present invention provides a method of producing a crystalline rare earth phosphate nanostructure. The method comprising: providing a rare earth metal precursor solution and providing a phosphate precursor solution; placing a porous membrane between the metal precursor solution and the phosphate precursor solution, wherein metal cations of the metal precursor solution and phosphate ions of the phosphate precursor solution react, thereby producing a crystalline rare earth metal phosphate nanostructure.

  13. A fully 3D approach for metal artifact reduction in computed tomography

    SciTech Connect

    Kratz, Baerbel; Weyers, Imke; Buzug, Thorsten M.

    2012-11-15

    Purpose: In computed tomography imaging metal objects in the region of interest introduce inconsistencies during data acquisition. Reconstructing these data leads to an image in spatial domain including star-shaped or stripe-like artifacts. In order to enhance the quality of the resulting image the influence of the metal objects can be reduced. Here, a metal artifact reduction (MAR) approach is proposed that is based on a recomputation of the inconsistent projection data using a fully three-dimensional Fourier-based interpolation. The success of the projection space restoration depends sensitively on a sensible continuation of neighboring structures into the recomputed area. Fortunately, structural information of the entire data is inherently included in the Fourier space of the data. This can be used for a reasonable recomputation of the inconsistent projection data. Methods: The key step of the proposed MAR strategy is the recomputation of the inconsistent projection data based on an interpolation using nonequispaced fast Fourier transforms (NFFT). The NFFT interpolation can be applied in arbitrary dimension. The approach overcomes the problem of adequate neighborhood definitions on irregular grids, since this is inherently given through the usage of higher dimensional Fourier transforms. Here, applications up to the third interpolation dimension are presented and validated. Furthermore, prior knowledge may be included by an appropriate damping of the transform during the interpolation step. This MAR method is applicable on each angular view of a detector row, on two-dimensional projection data as well as on three-dimensional projection data, e.g., a set of sequential acquisitions at different spatial positions, projection data of a spiral acquisition, or cone-beam projection data. Results: Results of the novel MAR scheme based on one-, two-, and three-dimensional NFFT interpolations are presented. All results are compared in projection data space and spatial

  14. Metal-ceramics based on nanostructured boron carbide

    NASA Astrophysics Data System (ADS)

    Antadze, M.; Chedia, R.; Tsagareishvili, O.; Mikeladze, A.; Gacheciladze, A.; Margiev, B.; Gabunia, D.; Tsuladze, T.; Khantadze, D.

    2012-11-01

    Boron carbide has unique physicochemical and mechanical properties such as: high modulus of elasticity, high value of a strength-to-density ratio, heightened wear-resistance in unfriendly environment, etc., however dense product of boron carbide is not widely used in the area of engineering due to low impact strength, brittleness and low thermal conductivity of this material. Recent efforts of the scientists working in this area are focused on creating the so-called hetero-modulus metal-ceramic composite materials comprised of high-modulus ceramic and a metallic phase as an elastic binder. Creation of effective boron carbide based hetero-modulus materials is possible when a) boron carbide has a high degree of dispersion; b) metallic binder has a high adhesion ability and low reactivity toward boron carbide. The technology developed for producing boron carbide based metal-ceramic materials provides pyrolysis (900-1100 °C) of the precursors comprised of amorphous boron, carbon-chain polymers and appropriate metal salts. Each particle of the obtained powder contains both - nanostructured components of boron carbide and of a binding metallic phase. The fabricated metal-ceramic product has heightened parameters of impact strength and thermal conductivity in parallel with the retained unique properties of boron carbide.

  15. Thermal expansion in 3d-metal Prussian Blue Analogs-A survey study

    SciTech Connect

    Adak, Sourav; Daemen, Luke L.; Hartl, Monika; Williams, Darrick; Summerhill, Jennifer; Nakotte, Heinz

    2011-11-15

    We present a comprehensive study of the structural properties and the thermal expansion behavior of 17 different Prussian Blue Analogs (PBAs) with compositions M{sup II}{sub 3}[(M'){sup III}(CN){sub 6}]{sub 2}.nH{sub 2}O and M{sup II}{sub 2}[Fe{sup II}(CN){sub 6}].nH{sub 2}O, where M{sup II}=Mn, Fe, Co, Ni, Cu and Zn, (M'){sup III}=Co, Fe and n is the number of water molecules, which range from 5 to 18 for these compounds. The PBAs were synthesized via standard chemical precipitation methods, and temperature-dependent X-ray diffraction studies were performed in the temperature range between -150 deg. C (123 K) and room-temperature. The vast majority of the studied PBAs were found to crystallize in cubic structures of space groups Fm3-bar m, F4-bar 3m and Pm3-bar m. The temperature dependence of the lattice parameters was taken to compute an average coefficient of linear thermal expansion in the studied temperature range. Of the 17 compounds, 9 display negative values for the average coefficient of linear thermal expansion, which can be as large as 39.7x{sup 1}0{sup -6} K{sup -1} for Co{sub 3}[Co(CN){sub 6}]{sub 2}.12H{sub 2}O. All of the M{sup II}{sub 3}[Co{sup III}(CN){sub 6}]{sub 2}.nH{sub 2}O compounds show negative thermal expansion behavior, which correlates with the Irving-Williams series for metal complex stability. The thermal expansion behavior for the PBAs of the M{sup II}{sub 3}[Fe{sup III}(CN){sub 6}]{sub 2}.nH{sub 2}O family are found to switch between positive (for M=Mn, Co, Ni) and negative (M=Cu, Zn) behavior, depending on the choice of the metal cation (M). On the other hand, all of the M{sup II}{sub 2}[Fe{sup II}(CN){sub 6}].nH{sub 2}O compounds show positive thermal expansion behavior. - Graphical Abstract: The structure of Prussian Blue analogs (PBAs) consists of two types of metal centered octahedral units connected by cyanide ligand. Lattice and interstitial water molecules are present in these framework structures. All the PBAs of the M{sub 3

  16. Giant perpendicular magnetocrystalline anisotropy of 3d transition-metal thin films on MgO

    SciTech Connect

    Nakamura, Kohji Ikeura, Yushi; Akiyama, Toru; Ito, Tomonori

    2015-05-07

    Magnetocrystalline anisotropy (MCA) of the Fe-based transition-metal thin films was investigated by means of first principles full-potential linearized augmented plane wave method. A giant perpendicular MCA (PMCA), up to 3 meV, was confirmed in a 7-layer Fe-Ni film/MgO(001), where an Fe{sub 2}/Ni/Fe/Ni/Fe{sub 2} atomic-layer alignment with a bcc-like-layer stacking and the Fe/MgO interfaces play key roles for leading to the large PMCA. Importantly, we find that the PMCA overcomes enough over the magnetic dipole-dipole anisotropy that favors the in-plane magnetization even when the film thickness increases.

  17. The stereochemical diversity of a new SNONS binucleating ligand towards 3d metal ions

    NASA Astrophysics Data System (ADS)

    Naik, Anil D.; Annigeri, Satish M.; Gangadharmath, Umesh B.; Revankar, Vidyanand K.; Mahale, Vinayak B.

    2002-06-01

    A new binucleating ligand containing phenoxide as an endogenous bridging group, 2,6-diformyl- p-cresol bis(2-furanthiocarboxyhydrazone) and its binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with chloride ion as an exogenous bridge, have been obtained. The complexes were characterized by elemental analysis, molar conductivities, magnetic moment measurements at room temperature, electronic, IR, 1H-NMR, EPR, FAB spectral studies and thermal data. The copper complex assumes a tetranuclear structure composed of two binuclear units related by a center of symmetry. The dimeric nature of copper(II) complex is supported by FAB. This complex is EPR silent. Room temperature magnetic moment reveals the operation of a significant antiferromagnetic spin exchange between the metal centers. Ligand and its copper and zinc complexes exhibit fluorescence at room temperature in DMF. All the compounds show an appreciable antimicrobial activity.

  18. Metrology of 3D nanostructures.

    SciTech Connect

    Barsic, Anthony; Piestun, Rafael; Boye, Robert R.

    2012-10-01

    We propose a superresolution technique to resolve dense clusters of blinking emitters. The method relies on two basic assumptions: the emitters are statistically independent, and a model of the imaging system is known. We numerically analyze the performance limits of the method as a function of the emitter density and the noise level. Numerical simulations show that five closely packed emitters can be resolved and localized to a precision of 17nm. The experimental resolution of five quantum dots located within a diffraction limited spot confirms the applicability of this approach.

  19. Solving the nanostructure problem: exemplified on metallic alloy nanoparticles.

    PubMed

    Petkov, Valeri; Prasai, Binay; Ren, Yang; Shan, Shiyao; Luo, Jin; Joseph, Pharrah; Zhong, Chuan-Jian

    2014-09-01

    With current technology moving rapidly toward smaller scales nanometer-size materials, hereafter called nanometer-size particles (NPs), are being produced in increasing numbers and explored for various useful applications ranging from photonics and catalysis to detoxification of wastewater and cancer therapy. Nature also is a prolific producer of useful NPs. Evidence can be found in ores on the ocean floor, minerals and soils on land and in the human body that, when water is excluded, is mostly made of proteins that are 6-10 nm in size and globular in shape. Precise knowledge of the 3D atomic-scale structure, that is how atoms are arranged in space, is a crucial prerequisite for understanding and so gaining more control over the properties of any material, including NPs. In the case of bulk materials such knowledge is fairly easy to obtain by Bragg diffraction experiments. Determining the 3D atomic-scale structure of NPs is, however, still problematic spelling trouble for science and technology at the nanoscale. Here we explore this so-called "nanostructure problem" from a practical point of view arguing that it can be solved when its technical, that is the inapplicability of Bragg diffraction to NPs, and fundamental, that is the incompatibility of traditional crystallography with NPs, aspects are both addressed properly. As evidence we present a successful and broadly applicable, 6-step approach to determining the 3D atomic-scale structure of NPs based on a suitable combination of a few experimental and computational techniques. This approach is exemplified on 5 nm sized Pd(x)Ni(100-x) particles (x = 26, 56 and 88) explored for catalytic applications. Furthermore, we show how once an NP atomic structure is determined precisely, a strategy for improving NP structure-dependent properties of particular interest to science and technology can be designed rationally and not subjectively as frequently done now. PMID:25030531

  20. 3D-HST GRISM SPECTROSCOPY OF A GRAVITATIONALLY LENSED, LOW-METALLICITY STARBURST GALAXY AT z = 1.847

    SciTech Connect

    Brammer, Gabriel B.; Sanchez-Janssen, Ruben; Labbe, Ivo; Franx, Marijn; Fumagalli, Mattia; Patel, Shannon; Da Cunha, Elisabete; Rix, Hans-Walter; Schmidt, Kasper B.; Van der Wel, Arjen; Erb, Dawn K.; Lundgren, Britt; Momcheva, Ivelina; Nelson, Erica; Skelton, Rosalind E.; Van Dokkum, Pieter G.; Wake, David A.; Whitaker, Katherine E.; Marchesini, Danilo; Quadri, Ryan

    2012-10-10

    We present Hubble Space Telescope (HST) imaging and spectroscopy of the gravitational lens SL2SJ02176-0513, a cusp arc at z = 1.847. The UV continuum of the lensed galaxy is very blue, which is seemingly at odds with its redder optical colors. The 3D-HST WFC3/G141 near-infrared spectrum of the lens reveals the source of this discrepancy to be extremely strong [O III] {lambda}5007 and H{beta} emission lines with rest-frame equivalent widths of 2000 {+-} 100 and 520 {+-} 40 A, respectively. The source has a stellar mass {approx}10{sup 8} M{sub Sun }, sSFR {approx} 100 Gyr{sup -1}, and detection of [O III] {lambda}4363 yields a metallicity of 12 + log (O/H) = 7.5 {+-} 0.2. We identify local blue compact dwarf analogs to SL2SJ02176-0513, which are among the most metal-poor galaxies in the Sloan Digital Sky Survey. The local analogs resemble the lensed galaxy in many ways, including UV/optical spectral energy distribution, spatial morphology, and emission line equivalent widths and ratios. Common to SL2SJ02176-0513 and its local counterparts is an upturn at mid-IR wavelengths likely arising from hot dust heated by starbursts. The emission lines of SL2SJ02176-0513 are spatially resolved owing to the combination of the lens and the high spatial resolution of HST. The lensed galaxy is composed of two clumps with combined size r{sub e} {approx}300 pc, and we resolve significant differences in UV color and emission line equivalent width between them. Though it has characteristics occasionally attributed to active galactic nuclei, we conclude that SL2SJ02176-0513 is a low-metallicity star-bursting dwarf galaxy. Such galaxies will be found in significant numbers in the full 3D-HST grism survey.

  1. Relative stability of normal vs. inverse spinel for 3d transition metal oxides as lithium intercalation cathodes.

    PubMed

    Bhattacharya, Jishnu; Wolverton, C

    2013-05-01

    Spinel oxides represent an important class of cathode materials for Li-ion batteries. Two major variants of the spinel crystal structure are normal and inverse. The relative stability of normal and inverse ordering at different stages of lithiation has important consequences in lithium diffusivity, voltage, capacity retention and battery life. In this paper, we investigate the relative structural stability of normal and inverse structures of the 3d transition metal oxide spinels with first-principles DFT calculations. We have considered ternary spinel oxides LixM2O4 with M = Ti, V, Cr, Mn, Fe, Co and Ni in both lithiated (x = 1) and delithiated (x = 0) conditions. We find that for all lithiated spinels, the normal structure is preferred regardless of the metal. We observe that the normal structure for all these oxides has a lower size mismatch between octahedral cations compared to the inverse structure. With delithiation, many of the oxides undergo a change in stability with vanadium in particular, showing a tendency to occupy tetrahedral sites. We find that in the delithiated oxide, only vanadium ions can access a +5 oxidation state which prefers tetrahedral coordination. We have also calculated the average voltage of lithiation for these spinels. The calculated voltages agree well with the previously measured and calculated values, wherever available. For the yet to be characterized spinels, our calculation provides voltage values which can motivate further experimental attention. Lastly, we observe that all the normal spinel oxides of the 3d transition metal series have a driving force for a transformation to the non-spinel structure upon delithiation. PMID:23529669

  2. Feasibility Study on 3-D Printing of Metallic Structural Materials with Robotized Laser-Based Metal Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Ding, Yaoyu; Kovacevic, Radovan

    2016-05-01

    Metallic structural materials continue to open new avenues in achieving exotic mechanical properties that are naturally unavailable. They hold great potential in developing novel products in diverse industries such as the automotive, aerospace, biomedical, oil and gas, and defense. Currently, the use of metallic structural materials in industry is still limited because of difficulties in their manufacturing. This article studied the feasibility of printing metallic structural materials with robotized laser-based metal additive manufacturing (RLMAM). In this study, two metallic structural materials characterized by an enlarged positive Poisson's ratio and a negative Poisson's ratio were designed and simulated, respectively. An RLMAM system developed at the Research Center for Advanced Manufacturing of Southern Methodist University was used to print them. The results of the tensile tests indicated that the printed samples successfully achieved the corresponding mechanical properties.

  3. Feasibility Study on 3-D Printing of Metallic Structural Materials with Robotized Laser-Based Metal Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Ding, Yaoyu; Kovacevic, Radovan

    2016-07-01

    Metallic structural materials continue to open new avenues in achieving exotic mechanical properties that are naturally unavailable. They hold great potential in developing novel products in diverse industries such as the automotive, aerospace, biomedical, oil and gas, and defense. Currently, the use of metallic structural materials in industry is still limited because of difficulties in their manufacturing. This article studied the feasibility of printing metallic structural materials with robotized laser-based metal additive manufacturing (RLMAM). In this study, two metallic structural materials characterized by an enlarged positive Poisson's ratio and a negative Poisson's ratio were designed and simulated, respectively. An RLMAM system developed at the Research Center for Advanced Manufacturing of Southern Methodist University was used to print them. The results of the tensile tests indicated that the printed samples successfully achieved the corresponding mechanical properties.

  4. Intra-chain superexchange couplings in quasi-1D 3d transition-metal magnetic compounds.

    PubMed

    Xiang, Hongping; Tang, Yingying; Zhang, Suyun; He, Zhangzhen

    2016-07-13

    The electronic structure and magnetic properties of the quasi-1D transition-metal borates PbMBO4 (M  =  Ti, V, Cr, Mn, Fe, Co) have been investigated by density functional theory, including electronic correlation. The results evidence PbCrBO4 and PbFeBO4 as antiferromagnetic (AFM) semiconductors (intra-chain AFM and inter-chain FM) and PbMnBO4 as a ferromagnetic (FM) semiconductor (both intra- and inter-chain FM) in accordance with experimental observations. For non-synthesized PbTiBO4, PbVBO4, and PbCoBO4, the ground-state magnetic structures are paramagnetic, FM, and paramagnetic, respectively. In this series of compounds, there are two kinds of superexchange couplings dominating their magnetic properties, i.e. the direction M-M delocalization superexchange and indirect M-O-M correlation superexchange. For PbMBO4 with M (3+) d  (n) , n  ⩽  3 (M  =  V and Cr), the main intra-chain spin coupling is the M-M t 2g-t 2g direct delocalization superexchange, while for PbMBO4 with M (3+) d  (n) , n  >  3 (M  =  Mn and Fe), the main intra-chain spin coupling is the near 90° M-O-M e g-p-e g indirect correlation superexchange. PMID:27213502

  5. Intra-chain superexchange couplings in quasi-1D 3d transition-metal magnetic compounds

    NASA Astrophysics Data System (ADS)

    Xiang, Hongping; Tang, Yingying; Zhang, Suyun; He, Zhangzhen

    2016-07-01

    The electronic structure and magnetic properties of the quasi-1D transition-metal borates PbMBO4 (M  =  Ti, V, Cr, Mn, Fe, Co) have been investigated by density functional theory, including electronic correlation. The results evidence PbCrBO4 and PbFeBO4 as antiferromagnetic (AFM) semiconductors (intra-chain AFM and inter-chain FM) and PbMnBO4 as a ferromagnetic (FM) semiconductor (both intra- and inter-chain FM) in accordance with experimental observations. For non-synthesized PbTiBO4, PbVBO4, and PbCoBO4, the ground-state magnetic structures are paramagnetic, FM, and paramagnetic, respectively. In this series of compounds, there are two kinds of superexchange couplings dominating their magnetic properties, i.e. the direction M–M delocalization superexchange and indirect M–O–M correlation superexchange. For PbMBO4 with M 3+ d  n , n  ⩽  3 (M  =  V and Cr), the main intra-chain spin coupling is the M–M t 2g–t 2g direct delocalization superexchange, while for PbMBO4 with M 3+ d  n , n  >  3 (M  =  Mn and Fe), the main intra-chain spin coupling is the near 90° M–O–M e g–p–e g indirect correlation superexchange.

  6. 3-D perpendicular assembly of single walled carbon nanotubes for complimentary metal oxide semiconductor interconnects.

    PubMed

    Kim, Tae-Hoon; Yilmaz, Cihan; Somu, Sivasubramanian; Busnaina, Ahmed

    2014-05-01

    Due to their superior electrical properties such as high current density and ballistic transport, carbon nanotubes (CNT) are considered as a potential candidate for future Very Large Scale Integration (VLSI) interconnects. However, direct incorporation of CNTs into Complimentary Metal Oxide Semiconductor (CMOS) architecture by conventional chemical vapor deposition (CVD) growth method is problematic since it requires high temperatures that might damage insulators and doped semiconductors in the underlying CMOS circuits. In this paper, we present a directed assembly method to assemble aligned CNTs into pre-patterned vias and perpendicular to the substrate. A dynamic electric field with a static offset is applied to provide the force needed for directing the SWNT assembly. It is also shown that by adjusting assembly parameters the density of the assembled CNTs can be significantly enhanced. This highly scalable directed assembly method is conducted at room temperature and pressure and is accomplished in a few minutes. I-V characterization of the assembled CNTs was conducted using a Zyvex nanomanipulator in a scanning electron microscope (SEM) and the measured value of the resistance is found to be 270 komega s. PMID:24734611

  7. Template Synthesis of Nanostructured Metals using Cellulose Nanocrystal

    SciTech Connect

    Shin, Yongsoon; Exarhos, Gregory J.

    2009-11-01

    In this chapter, cellulose nanocrystal (CNXL) has been used as a template and reducing agent for synthesizing nanoscale inorganic solids such as metal oxide, metal carbide, and nanocrystalline metals. CNXL selectively nucleates metal or metal oxide phases in ordered arrangements commensurate with the attendant structure and chemistry of the fiber. The reaction has an analogy to the well-known Tollen’s reagent where addition of an aldehyde or glucose analyte to a glass vessel containing a soluble ammoniacal silver complex causes reduction of the silver to form a mirror on the vessel surface. For the synthesis of TiO2, CNXL produced mesoporous anatase with 5-10 nm particle sizes and 170-200 m2/g surface area after air-calcination. Silica-infiltrated CNXL produced very homogeneous SiC nanowires with 70 nm in diameter at 1400 oC in Ar. For the syntheses of metal nanoparticles, upon addition of aqueous metal ion containing solutions (Cu(II), Ni(II), Ag(I), Au(III), Pd(II), Pt(IV), or even selenite, Se(IV)) into the CNXL suspension, reduction to the metal occurs under hydrothermal conditions to form ordered metal nanostructures. Ni (II) and Cu(II) ions required high temperature (300-400 oC) to be reduced due to their low reduction potentials. However, metal ions including Ag(I), Au(III), Pt(IV), Pd(II), Se(IV) needed lower temperatures (160-200 oC) to be reduced. Enhanced catalytic activity on these templated surfaces has been demonstrated for a methylene-blue dye photo-induced decomposition (Se nanocrystals resident on crystalline cellulose).

  8. Localized surface plasmon of quasi-one-dimensional metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Liu, Mingzhao

    2007-05-01

    The plasmon resonance of noble metal nanoparticles provides interesting optical properties in the visible and near-infrared region, and is highly tunable by varying the shape and the composition of the nanoparticles. The rod-like gold nanostructures can be synthesized by a seed-mediated method in aqueous surfactant solutions. Starting from different types of gold seeds, either single crystalline gold nanorods or penta-fold twinned gold bipyramids can be synthesized in decent yield with silver(I) added into the growth solution. These nanostructures have pronounced plasmon resonance varying in the 1˜2 eV range. The bipyramids are strikingly monodisperse in shape, which leads to the sharpest ensemble longitudinal plasmon resonance reported so far for metal colloid solutions. A mechanism based on the underpotential deposition of silver was thus suggested to explain the essential role of Ag(I) in the growth process. The optical spectra of the gold colloids were simulated with the finite-difference time-domain (FDTD) method. The results show excellent agreement with recent experimental optical spectra. The local field enhancement (|E|/|E0|) was studied at the plasmon resonance. Sharper structural features produce more significant enhancement and the largest enhancement of more than a factor of 200 is seen around the poles of the bipyramid. A large internal field enhancement by more than a factor of 30 is found for the bipyramids, which suggests that they will exhibit very strong optical nonlinearities. The plasmon can be further tuned by introducing the core/shell nanostructures such as metal/metal or metal/semiconductor nanorods. Following a simple procedure, a homogeneous layer of silver with 1-4 nm thickness can be plated onto the gold nanorods, which shifts the longitudinal plasmon mode of the nanorods toward blue. The silver layer can be converted to semiconductors silver sulfide or selenide, with the longitudinal plasmon resonance tuned toward red. The metal

  9. Electronic properties of 3d transitional metal pnictides: A comparative study by optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Cheng, B.; Hu, B. F.; Chen, R. Y.; Xu, G.; Zheng, P.; Luo, J. L.; Wang, N. L.

    2012-10-01

    Single-crystalline KFe2As2 and CaT2As2 (T=Fe, Co, Ni, and Cu) are synthesized and investigated by resistivity, susceptibility, and optical spectroscopy. It is found that CaCu2As2 exhibits a similar transition to the lattice abrupt collapse transitions discovered in CaFe2(As1-xPx)2 and Ca1-xRxFe2As2 (R = rare-earth element). The resistivity of KFe2As2 and CaT2As2 (T=Fe, Co, Ni, and Cu) approximately follows the similar T2 dependence at low temperature, but the magnetic behaviors vary with different samples. Optical measurement reveals that the optical response of CaCu2As2 is not sensitive to the transition at 50 K, with no indication of development of a new energy gap below the transition temperature. Using Drude-Lorentz model, we find that two Drude terms, a coherent one and an incoherent one, can fit the low-energy optical conductivity of KFe2As2 and CaT2As2 (T=Fe, Co, and Ni) very well. However, in CaCu2As2, which is a sp-band metal, the low-energy optical conductivity can be well described by a coherent Drude term. Lack of the incoherent Drude term in CaCu2As2 may be attributed to a weaker electronic correlation than in KFe2As2 and CaT2As2 (T=Fe, Co, and Ni). Spectral weight analysis of these samples indicates that the unconventional spectral weight transfer, which is related to Hund's coupling energy JH, is only observed in iron pnictides, supporting the viewpoint that JH may be a key clue in the search for the mechanism of magnetism and superconductivity in pnictides.

  10. Defect energetics and magnetic properties of 3 d-transition-metal-doped topological crystalline insulator SnTe

    NASA Astrophysics Data System (ADS)

    Wang, Na; Wang, JianFeng; Si, Chen; Gu, Bing-Lin; Duan, WenHui

    2016-08-01

    The introduction of magnetism in SnTe-class topological crystalline insulators is a challenging subject with great importance in the quantum device applications. Based on the first-principles calculations, we have studied the defect energetics and magnetic properties of 3 d transition-metal (TM)-doped SnTe. We find that the doped TM atoms prefer to stay in the neutral states and have comparatively high formation energies, suggesting that the uniform TMdoping in SnTe with a higher concentration will be difficult unless clustering. In the dilute doping regime, all the magnetic TMatoms are in the high-spin states, indicating that the spin splitting energy of 3 d TM is stronger than the crystal splitting energy of the SnTe ligand. Importantly, Mn-doped SnTe has relatively low defect formation energy, largest local magnetic moment, and no defect levels in the bulk gap, suggesting that Mn is a promising magnetic dopant to realize the magnetic order for the theoretically-proposed large-Chern-number quantum anomalous Hall effect (QAHE) in SnTe.

  11. 3D metal-organic framework as highly efficient biosensing platform for ultrasensitive and rapid detection of bisphenol A.

    PubMed

    Wang, Xue; Lu, Xianbo; Wu, Lidong; Chen, Jiping

    2015-03-15

    As is well known, bisphenol A (BPA), usually exists in daily plastic products, is one of the most important endocrine disrupting chemicals. In this work, copper-centered metal-organic framework (Cu-MOF) was synthesized, which was characterized by SEM, TEM, XRD, FTIR and electrochemical method. The resultant Cu-MOF was explored as a robust electrochemical biosensing platform by choosing tyrosinase (Tyr) as a model enzyme for ultrasensitive and rapid detection of BPA. The Cu-MOF provided a 3D structure with a large specific surface area, which was beneficial for enzyme and BPA absorption, and thus improved the sensitivity of the biosensor. Furthermore, Cu-MOF as a novel sorbent could increase the available BPA concentration to react with tyrosinase through π-π stacking interactions between BPA and Cu-MOF. The Tyr biosensor exhibited a high sensitivity of 0.2242A M(-1) for BPA, a wide linear range from 5.0×10(-8) to 3.0×10-6moll(-1), and a low detection limit of 13nmoll(-1). The response time for detection of BPA is less than 11s. The proposed method was successfully applied to rapid and selective detection of BPA in plastic products with satisfactory results. The recoveries are in the range of 94.0-101.6% for practical applications. With those remarkable advantages, MOFs-based 3D structures show great prospect as robust biosensing platform for ultrasensitive and rapid detection of BPA. PMID:25461172

  12. A nanoporous 3D zinc(II) metal-organic framework for selective absorption of benzaldehyde and formaldehyde

    NASA Astrophysics Data System (ADS)

    Moradpour, Tahereh; Abbasi, Alireza; Van Hecke, Kristof

    2015-08-01

    A new 3D nanoporous metal-organic framework (MOF), [[Zn4O(C24H15N6O6)2(H2O)2]·6H2O·DMF]n (1) based on 4,4‧,4″-s-triazine-1,3,5-triyltri-p-aminobenzoate (TATAB) ligand was solvothermally synthesized and characterized by single-crystal X-ray diffraction, Powder X-ray diffraction (PXRD), infrared spectroscopy (IR) and Brunauer-Emmett-Teller (BET) analyses. X-ray single crystal diffraction analysis reveals that 1 exhibits a 3D network with new kvh1 topology. Semi-empirical (AM1) calculations were carried out to obtain stable conformers for TATAB ligand. In addition, the absorption of two typical aldehydes (benzaldehyde and formaldehyde) in the presence of 1 was investigated and the effect of the aldehyde concentration, exposure time and temperature was studied. It was found that compound 1 has a potential for the absorption of aldehydes under mild conditions.

  13. Spin Dependent Transport Properties of Metallic and Semiconducting Nanostructures

    NASA Astrophysics Data System (ADS)

    Sapkota, Keshab R.

    Present computing and communication devices rely on two different classes of technologies; information processing devices are based on electrical charge transport in semiconducting materials while information storage devices are based on orientation of electron spins in magnetic materials. A realization of a hybrid-type device that is based on charge as well as spin properties of electrons would perform both of these actions thereby enhancing computation power to many folds and reducing power consumptions. This dissertation focuses on the fabrication of such spin-devices based on metallic and semiconducting nanostructures which can utilize spin as well as charge properties of electrons. A simplified design of the spin-device consists of a spin injector, a semiconducting or metallic channel, and a spin detector. The channel is the carrier of the spin signal from the injector to the detector and therefore plays a crucial role in the manipulation of spin properties in the device. In this work, nanostructures like nanowires and nanostripes are used to function the channel in the spin-device. Methods like electrospinning, hydrothermal, and wet chemical were used to synthesize nanowires while physical vapor deposition followed by heat treatment in controlled environment was used to synthesis nanostripes. Spin-devices fabrication of the synthesized nanostructures were carried out by electron beam lithography process. The details of synthesis of nanostructures, device fabrication procedures and measurement techniques will be discussed in the thesis. We have successfully fabricated the spin-devices of tellurium nanowire, indium nanostripe, and indium oxide nanostripe and studied their spin transport properties for the first time. These spin-devices show large spin relaxation length compared to normal metals like copper and offer potentials for the future technologies. Further, Heusler alloys nanowires like nanowires of Co 2FeAl were synthesized and studied for electrical

  14. Importance of polypyrrole in constructing 3D hierarchical carbon nanotube@MnO2 perfect core-shell nanostructures for high-performance flexible supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhou, Jinyuan; Zhao, Hao; Mu, Xuemei; Chen, Jiayi; Zhang, Peng; Wang, Yaling; He, Yongmin; Zhang, Zhenxing; Pan, Xiaojun; Xie, Erqing

    2015-08-01

    This study reports the preparation of 3D hierarchical carbon nanotube (CNT) @MnO2 core-shell nanostructures under the assistance of polypyrrole (PPy). The as-prepared CNT@PPy@MnO2 core-shell structures show a perfect coating of MnO2 on each CNT and, more importantly, a robust bush-like pseudocapacitive shell to effectively increase the specific surface area and enhance the ion accessibility. As expected, a high specific capacity of 490-530 F g-1 has been achieved from CNT@PPy@MnO2 single electrodes. And about 98.5% of the capacity is retained after 1000 charge/discharge cycles at a current density of 5 A g-1. Furthermore, the assembled asymmetric CNT@PPy@MnO2//AC capacitors show the maximum energy density of 38.42 W h kg-1 (2.24 mW h cm-3) at a power density of 100 W kg-1 (5.83 mW cm-3), and they maintain 59.52% of the initial value at 10 000 W kg-1 (0.583 W cm-3). In addition, the assembled devices show high cycling stabilities (89.7% after 2000 cycles for asymmetric and 87.2% for symmetric), and a high bending stability (64.74% after 200 bending tests). This ability to obtain high energy densities at high power rates while maintaining high cycling stability demonstrates that this well-designed structure could be a promising electrode material for high-performance supercapacitors.This study reports the preparation of 3D hierarchical carbon nanotube (CNT) @MnO2 core-shell nanostructures under the assistance of polypyrrole (PPy). The as-prepared CNT@PPy@MnO2 core-shell structures show a perfect coating of MnO2 on each CNT and, more importantly, a robust bush-like pseudocapacitive shell to effectively increase the specific surface area and enhance the ion accessibility. As expected, a high specific capacity of 490-530 F g-1 has been achieved from CNT@PPy@MnO2 single electrodes. And about 98.5% of the capacity is retained after 1000 charge/discharge cycles at a current density of 5 A g-1. Furthermore, the assembled asymmetric CNT@PPy@MnO2//AC capacitors show the

  15. Self-arrangement of nanoparticles toward crystalline metal oxides with high surface areas and tunable 3D mesopores

    PubMed Central

    Lee, Hyung Ik; Lee, Yoon Yun; Kang, Dong-Uk; Lee, Kirim; Kwon, Young-Uk; Kim, Ji Man

    2016-01-01

    We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity. At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework. Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes. A simple control of the Si/Ti ratio verified the versatility of the present method through the successful control of mean pore diameter in the range of 2–35 nm and specific surface area in the ranges of 180–250 m2 g−1. The present synthesis method is successfully extended to other metal oxides, their mixed oxides and analogues with different particle sizes, regarding as a general method for mesoporous metal (or mixed metal) oxides. PMID:26893025

  16. Self-arrangement of nanoparticles toward crystalline metal oxides with high surface areas and tunable 3D mesopores

    NASA Astrophysics Data System (ADS)

    Lee, Hyung Ik; Lee, Yoon Yun; Kang, Dong-Uk; Lee, Kirim; Kwon, Young-Uk; Kim, Ji Man

    2016-02-01

    We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity. At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework. Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes. A simple control of the Si/Ti ratio verified the versatility of the present method through the successful control of mean pore diameter in the range of 2-35 nm and specific surface area in the ranges of 180-250 m2 g-1. The present synthesis method is successfully extended to other metal oxides, their mixed oxides and analogues with different particle sizes, regarding as a general method for mesoporous metal (or mixed metal) oxides.

  17. Self-arrangement of nanoparticles toward crystalline metal oxides with high surface areas and tunable 3D mesopores.

    PubMed

    Lee, Hyung Ik; Lee, Yoon Yun; Kang, Dong-Uk; Lee, Kirim; Kwon, Young-Uk; Kim, Ji Man

    2016-01-01

    We demonstrate a new design concept where the interaction between silica nanoparticles (about 1.5 nm in diameter) with titania nanoparticles (anatase, about 4 nm or 6 nm in diameter) guides a successful formation of mesoporous titania with crystalline walls and controllable porosity. At an appropriate solution pH (~1.5, depending on the deprotonation tendencies of two types of nanoparticles), the smaller silica nanoparticles, which attach to the surface of the larger titania nanoparticles and provide a portion of inactive surface and reactive surface of titania nanoparticles, dictate the direction and the degree of condensation of the titania nanoparticles, resulting in a porous 3D framework. Further crystallization by a hydrothermal treatment and subsequent removal of silica nanoparticles result in a mesoporous titania with highly crystalline walls and tunable mesopore sizes. A simple control of the Si/Ti ratio verified the versatility of the present method through the successful control of mean pore diameter in the range of 2-35 nm and specific surface area in the ranges of 180-250 m(2) g(-1). The present synthesis method is successfully extended to other metal oxides, their mixed oxides and analogues with different particle sizes, regarding as a general method for mesoporous metal (or mixed metal) oxides. PMID:26893025

  18. The K x-ray line structures of the 3d-transition metals in warm dense plasma

    NASA Astrophysics Data System (ADS)

    Szymańska, E.; Syrocki, Ł.; Słabkowska, K.; Polasik, M.; Rzadkiewicz, J.

    2016-09-01

    The shapes and positions of the Kα1 and Kα2 x-ray lines for 3d-transition metals can vary substantially as electrons are stripped from the outer-shells. This paper shows the detailed line shapes for nickel and zinc, obtained by calculations with a multiconfiguration Dirac-Fock method that includes Breit interaction and quantum electrodynamics corrections. The line shapes can be useful in interpreting hot, dense plasmas with energetic electrons for which the K x-ray lines are optically thin, as may be produced by pulsed power machines such as the plasma-filled rod pinch diode or the plasma focus, or in short-pulsed high power laser plasmas.

  19. Structural, electronic, and magnetic properties of 3D metal trioxide and tetraoxide superhalogen cluster-doped monolayer BN

    NASA Astrophysics Data System (ADS)

    Meng, Jingjing; Li, Dan; Niu, Yuan; Zhao, Hongmin; Liang, Chunjun; He, Zhiqun

    2016-07-01

    The structural, electronic, and magnetic properties of monolayer BN doped with 3D metal trioxide and tetraoxide superhalogen clusters are investigated using first-principle calculations. TMO3(4)-doped monolayer BN exhibits a low negative formation energy, whereas TM atoms embedded in monolayer BN show a high positive formation energy. TMO3(4) clusters are embedded more easily in monolayer BN than TM atoms. Compared with TMO3-doped structures, TMO4-doped structures have a higher structural stability because of their higher binding energies. Given their low negative formation energies, TMO4-doped structures are more favored for specific applications than TMO3-doped structures and TM atom-doped structures. Large magnetic moments per supercell and significant ferromagnetic couplings between a TM atom and neighboring B and N atoms on the BN layer were observed in all TMO4-doped structures, except for TiO4-doped structures.

  20. First principles study on spin and orbital magnetism of 3d transition metal monatomic nanowires (Mn, Fe and Co).

    PubMed

    Sargolzaei, Mahdi; Samaneh Ataee, S

    2011-03-30

    We have demonstrated the electronic structure and magnetic properties of 3d transition metal nanowires (Mn, Fe and Co) in the framework of relativistic density functional theory. The equilibrium bond lengths were optimized using the generalized gradient approximation. In a full relativistic regime individual spin and orbital moments induced from spin polarization via spin-orbit coupling were calculated. In order to get an upper estimate for orbital moments, we used an orbital polarization correction to our exchange-correlation functional. We found that the orbital magnetic moments of Fe and Co linear chains are strongly enhanced in the presence of an orbital polarization correction. We have calculated the exchange coupling parameters between two nearest-neighbor magnetic atoms according to a Heisenberg-like model in the presence of the orbital polarization correction. We found that the Co and Fe nanowires behave like a ferromagnetic linear chain whereas a Mn monatomic nanowire remains antiferromagnetic. PMID:21378443

  1. Incorporating hierarchical nanostructured carbon counter electrode into metal-free organic dye-sensitized solar cell.

    PubMed

    Fang, Baizeng; Fan, Sheng-Qiang; Kim, Jung Ho; Kim, Min-Sik; Kim, Minwoo; Chaudhari, Nitin K; Ko, Jaejung; Yu, Jong-Sung

    2010-07-01

    Hierarchical nanostructured carbon with a hollow macroporous core of ca. 60 nm in diameter in combination with mesoporous shell of ca. 30 nm in thickness has been explored as counter electrode in metal-free organic dye-sensitized solar cell. Compared with other porous carbon counterparts such as activated carbon and ordered mesoporous carbon CMK-3 and Pt counter electrode, the superior structural characteristics including large specific surface area and mesoporous volume and particularly the unique hierarchical core/shell nanostructure along with 3D large interconnected interstitial volume guarantee fast mass transport in hollow macroporous core/mesoporous shell carbon (HCMSC), and enable HCMSC to have highly enhanced catalytic activity toward the reduction of I(3)(-), and accordingly considerably improved photovoltaic performance. HCMSC exhibits a V(oc) of 0.74 V, which is 20 mV higher than that (i.e., 0.72 V) of Pt. In addition, it also demonstrates a fill factor of 0.67 and an energy conversion efficiency of 7.56%, which are markedly higher than those of its carbon counterparts and comparable to that of Pt (i.e., fill factor of 0.70 and conversion efficiency of 7.79%). Furthermore, HCMSC possesses excellent chemical stability in the liquid electrolyte containing I(-)/I(3)(-) redox couples, namely, after 60 days of aging, ca. 87% of its initial efficiency is still achieved by the solar cell based on HCMSC counter electrode. PMID:20334406

  2. Self-assembly synthesis of precious-metal-free 3D ZnO nano/micro spheres with excellent photocatalytic hydrogen production from solar water splitting

    NASA Astrophysics Data System (ADS)

    Guo, Si-yao; Zhao, Tie-jun; Jin, Zu-quan; Wan, Xiao-mei; Wang, Peng-gang; Shang, Jun; Han, Song

    2015-10-01

    A simple and straightforward solution growth routine is developed to prepare microporous 3D nano/micro ZnO microsphere with a large BET surface area of 288 m2 g-1 at room temperature. The formation mechanism of the hierarchical 3D nano/micro ZnO microsphere and its corresponding hydrogen evolution performance has been deeply discussed. In particular, this novel hierarchical 3D ZnO microspheres performs undiminished hydrogen evolution for at least 24 h under simulated solar light illumination, even under the condition of no precious metal as cocatalyst. Since the complex production process of photocatalysts and high cost of precious metal cocatalyst remains a major constraint that hinders the application of solar water splitting, this 3D nano/micro ZnO microspheres could be expected to be applicable in the precious-metal-free solar water splitting system due to its merits of low cost, simple procedure and high catalytic activity.

  3. Strong Casimir force reduction through metallic surface nanostructuring.

    PubMed

    Intravaia, Francesco; Koev, Stephan; Jung, Il Woong; Talin, A Alec; Davids, Paul S; Decca, Ricardo S; Aksyuk, Vladimir A; Dalvit, Diego A R; López, Daniel

    2013-01-01

    The Casimir force between bodies in vacuum can be understood as arising from their interaction with an infinite number of fluctuating electromagnetic quantum vacuum modes, resulting in a complex dependence on the shape and material of the interacting objects. Becoming dominant at small separations, the force has a significant role in nanomechanics and object manipulation at the nanoscale, leading to a considerable interest in identifying structures where the Casimir interaction behaves significantly different from the well-known attractive force between parallel plates. Here we experimentally demonstrate that by nanostructuring one of the interacting metal surfaces at scales below the plasma wavelength, an unexpected regime in the Casimir force can be observed. Replacing a flat surface with a deep metallic lamellar grating with sub-100 nm features strongly suppresses the Casimir force and for large inter-surfaces separations reduces it beyond what would be expected by any existing theoretical prediction. PMID:24071657

  4. Strong Casimir force reduction through metallic surface nanostructuring

    PubMed Central

    Intravaia, Francesco; Koev, Stephan; Jung, Il Woong; Talin, A. Alec; Davids, Paul S.; Decca, Ricardo S.; Aksyuk, Vladimir A.; Dalvit, Diego A. R.; López, Daniel

    2013-01-01

    The Casimir force between bodies in vacuum can be understood as arising from their interaction with an infinite number of fluctuating electromagnetic quantum vacuum modes, resulting in a complex dependence on the shape and material of the interacting objects. Becoming dominant at small separations, the force has a significant role in nanomechanics and object manipulation at the nanoscale, leading to a considerable interest in identifying structures where the Casimir interaction behaves significantly different from the well-known attractive force between parallel plates. Here we experimentally demonstrate that by nanostructuring one of the interacting metal surfaces at scales below the plasma wavelength, an unexpected regime in the Casimir force can be observed. Replacing a flat surface with a deep metallic lamellar grating with sub-100 nm features strongly suppresses the Casimir force and for large inter-surfaces separations reduces it beyond what would be expected by any existing theoretical prediction. PMID:24071657

  5. Photoelectric properties in metal ion modified DNA nanostructure.

    PubMed

    Kulkarni, Atul; Dugasani, Sreekantha Reddy; Jang Ah Kim; Kim; Sung Ha Park; Taesung Kim

    2015-08-01

    Due to specific or as designed self-assembly, DNA nanostructures gaining popularity in various nanoscale electronic applications. Herein, a novel divalent metal ion-DNA complex known as M-DNA have been investigated for its photoelectric characteristics. The increased conductivity of M-DNA thin films is attributed to the metal ion electrical and optical properties. The gate voltage effect along with illumination on the conductivity of M-DNA demonstrates that M-DNA can be used as an active element of a field-effect transistor. The Zn DNA shows maximum conductivity of 300μS/cm at 480 nm light illumination suggest that M-DNA can be utilized in nano-opto-electronics and bio-sensing applications. PMID:26737260

  6. Laser Nanostructurization of the Metal and Alloy Surfaces

    NASA Astrophysics Data System (ADS)

    Kanavin, Andrei; Kozlovskaya, Natalia; Krokhin, Oleg; Zavestovskaya, Irina

    2010-10-01

    The results from experimental and theoretical investigation of material pulsed laser treatment aimed at obtaining nano- and microstructured surface are presented. An experiment has been performed on the modification of indium surface using a solid-state diode-pumped laser. It has been shown that nano- and micro-size structures are formed under laser melting and fast crystallization of the metal surface. The kinetics of the crystallization of metals under superfast cooling. The distribution function for crystalline nuclei dimensions is analytically found within the framework of the classical kinetic equation in case of superfast temperature changing. The average number of particles in the crystalline nuclei and relative volume of the crystalline phase are determined as functions of thermodynamic and laser treatment regime parameters. Good agreement is observed with experimental results for ultrashort laser pulses induced micro- and nanostructures production.

  7. Electrodes synthesized from carbon nanostructures coated with a smooth and conformal metal adlayer

    DOEpatents

    Adzic, Radoslav; Harris, Alexander

    2014-04-15

    High-surface-area carbon nanostructures coated with a smooth and conformal submonolayer-to-multilayer thin metal films and their method of manufacture are described. The preferred manufacturing process involves the initial oxidation of the carbon nanostructures followed by a surface preparation process involving immersion in a solution with the desired pH to create negative surface dipoles. The nanostructures are subsequently immersed in an alkaline solution containing a suitable quantity of non-noble metal ions which adsorb at surface reaction sites. The metal ions are then reduced via chemical or electrical means. The nanostructures are exposed to a solution containing a salt of one or more noble metals which replace adsorbed non-noble surface metal atoms by galvanic displacement. The process can be controlled and repeated to obtain a desired film coverage. The resulting coated nanostructures may be used, for example, as high-performance electrodes in supercapacitors, batteries, or other electric storage devices.

  8. 3D-FEM analysis of SPP excitation through nanoholes in asymmetric metal-insulator-metal structure at tip of circular truncated conical fiber

    NASA Astrophysics Data System (ADS)

    Oshikane, Y.; Murai, K.; Nakano, M.

    2014-09-01

    3D-electromagnetic (EM) analysis of surface plasmon polaritons (SPPs) excited by a single-mode (SM) propagation of visible lightwave in an optical fiber has been studied with a 3D-FEM package based on a finite element method. End of the fiber is formed to be a circular cone by wet etching process, and is FIBed to make a circular truncated conical shape with a flat circular surface a few micrometers in diameter. The flat end is covered with three layers of asymmetric metalinsulator- metal structure, thin metallic layer (M1), thick insulator layer (I), and thick metallic layer (M2), respectively. The outermost M2 layer has FIBed nanoholes to convert light waves at the extremity of the fiber into SPPs efficiently, and a bright tiny point light source will be generated on the surface of the M2 layer. In this study, the 3D-FEM models consists of both the MIM structure and the shrinking optical fiber tip coated with a metallic thin film has been designed and analyzed numerically. By applying perfect electric conductor and perfect magnetic conductor to planes containing the axis of rotation, the FEM model has a quarter of the circular truncated conical shape. The FEM analysis is formed in two steps. At the first step, a FEM mode analysis is performed to obtain a solution corresponding to the SM propagation in the fiber. The second level of action is the FEM analysis of EM field in the whole of model to find a stationary solution with the solution of mode analysis. Characteristic of wavelength-dependent excitation, propagation, and focusing of the SPPs will be presented with several experimental results of trial products of the fiber tip.

  9. Self-Supplied Nano-Fusing and Transferring Metal Nanostructures via Surface Oxide Reduction.

    PubMed

    Ahn, Jaeho; Seo, Ji-Won; Kim, Jong Yun; Lee, Jaemin; Cho, Changsoon; Kang, Juhoon; Choi, Sung-Yool; Lee, Jung-Yong

    2016-01-20

    Here, we demonstrate that chemical reduction of oxide layers on metal nanostructures fuses junctions at nanoscale to improve the opto-electrical performance, and to ensure environmental stability of the interconnected nanonetwork. In addition, the reducing reaction lowers the adhesion force between metal nanostructures and substrates, facilitating the detachment of them from substrates. Detached metal nanonetworks can be easily floated on water and transferred onto various substrates including hydrophobic, floppy, and curved surfaces. Utilizing the detached metal nanostructures, semitransparent organic photovoltaics is fabricated, presenting the applicability of proposed reduction treatment in the device applications. PMID:26700597

  10. Dodecanuclear 3d/4f-metal clusters with a 'Star of David' topology: single-molecule magnetism and magnetocaloric properties.

    PubMed

    Alexandropoulos, Dimitris I; Cunha-Silva, Luís; Lorusso, Giulia; Evangelisti, Marco; Tang, Jinkui; Stamatatos, Theocharis C

    2016-01-28

    A family of interwoven molecular inorganic knots, shaped like the 'Star of David', was prepared by the employment of naphthalene-2,3-diol in 3d/4f-metal cluster chemistry; the isoskeletal dodecanuclear compounds exhibit slow relaxation of the magnetization and magnetocaloric properties, depending on the metal ion. PMID:26666673

  11. The Relationship Between Glass Formability and the Properties of the Bcc Phase in TITANIUM-3D Metal Alloys

    NASA Astrophysics Data System (ADS)

    Sinkler, Wharton

    The present study concerns glass formation and the beta (bcc) phase in Ti-3d metal systems. beta phase stability is related to amorphization, because the formability and stability of metallic glasses depends on the relative thermodynamic instability of chemically disordered crystalline solid solution phases (Johnson 1986). Correlations are found in this series of alloys which support a connection between electronic characteristics of the bcc phase and the tendency for glass formation. Electron irradiation-induced amorphization in Ti-3d metal systems is investigated as a function of temperature and DeltaN, the group number difference between Ti and the solute. DeltaN is made continuous by using a series of pseudobinary Laves compounds Ti(M1_{x}M2 _{(1-x)}_2. For DeltaN <= 2.2 (between TiCr_2 and TiMn _2) low temperature irradiation damage induces oriented precipitation of the beta (bcc) solid solution phase from the damaged compound. For DeltaN > 2.2 amorphization occurs. beta-phase precipitation under irradiation suggests that beta phase stability is continuously enhanced as Delta N decreases. Diffuse omega scattering in the quenched Ti-Cr beta phase is investigated using electron diffraction and low temperature electron irradiation. A new model of the short range ordered atomic displacements causing the diffuse scattering is developed. Based on this model, it is proposed that the structure reflects chemical short range order. This is supported by irradiation results on the beta phase. A correlation is found between the diffuse scattering and the valence electron concentration. The explanation proposed for this correlation is that the chemical ordering in the beta phase is driven by Fermi surface nesting. Results of annealing of quenched beta Ti-Cr are presented, and are compared with reports of annealing-induced amorphization of this phase (Blatter et al. 1988; Yan et al. 1993). Amorphization is not reproduced. A metastable compound phase beta ^{''} precipitates

  12. Pore-controlled formation of 0D metal complexes in anionic 3D metal-organic frameworks

    SciTech Connect

    Zhang, MW; Bosch, M; Zhou, HC

    2015-01-01

    The host-guest chemistry between a series of anionic MOFs and their trapped counterions was investigated by single crystal XRD. The PCN-514 series contains crystallographically identifiable metal complexes trapped in the pores, where their formation is controlled by the size and shape of the MOF pores. A change in the structure and pore size of PCN-518 indicates that the existence of guest molecules may reciprocally affect the formation of host MOFs.

  13. Metal encapsulating carbon nanostructures from oligoalkyne metal complexes

    SciTech Connect

    Dosa, P.I.; Erben, C.; Iyer, V.S.; Vollhardt, K.P.C.; Wasser, I.M.

    1999-11-10

    Carbon nanotubes, onions, and related closed-shell carbon particles have commanded extensive recent attention because of their potential applications as unique electronic, magnetic, and mechanically robust materials. When filled with metals, such nanocapsules have additional promise as magnetic particles, contrasting agents, protecting cloaks, and catalysts and in other applications. Among the various methods for their preparation, the transition metal (especially Fe, Co, and Ni) catalyzed pyrolysis of small organic molecules has shown promise for larger scale production and in structural control. While the use of organometallic complexes as solid catalyst precursors or copyrolytic gaseous ingredients has been reported, all of these studies have been limited to gas-phase experiments at relatively high temperatures. There is very little literature that deals with the organic solid-state generation of carbon nanotubes. The latter suffers from extreme conditions, poor yields, or not readily modifiable starting materials. Development of synthetic organic approaches to closed shell large carbon structures is desirable but in its infancy. Here the authors present a significant step in its progress.

  14. Mesoporous magnetic secondary nanostructures as versatile adsorbent for efficient scavenging of heavy metals

    PubMed Central

    Bhattacharya, Kakoli; Parasar, Devaborniny; Mondal, Bholanath; Deb, Pritam

    2015-01-01

    Porous magnetic secondary nanostructures exhibit high surface area because of the presence of plentiful interparticle spaces or pores. Mesoporous Fe3O4 secondary nanostructures (MFSNs) have been studied here as versatile adsorbent for heavy metal scavenging. The porosity combined with magnetic functionality of the secondary nanostructures has facilitated efficient heavy metal (As, Cu and Cd) remediation from water solution within a short period of contact time. It is because of the larger surface area of MFSNs due to the porous network in addition to primary nanostructures which provides abundant adsorption sites facilitating high adsorption of the heavy metal ions. The brilliance of adsorption property of MFSNs has been realized through comprehensive adsorption studies and detailed kinetics. Due to their larger dimension, MFSNs help in overcoming the Brownian motion which facilitates easy separation of the metal ion sorbed secondary nanostructures and also do not get drained out during filtration, thus providing pure water. PMID:26602613

  15. Mesoporous magnetic secondary nanostructures as versatile adsorbent for efficient scavenging of heavy metals

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Kakoli; Parasar, Devaborniny; Mondal, Bholanath; Deb, Pritam

    2015-11-01

    Porous magnetic secondary nanostructures exhibit high surface area because of the presence of plentiful interparticle spaces or pores. Mesoporous Fe3O4 secondary nanostructures (MFSNs) have been studied here as versatile adsorbent for heavy metal scavenging. The porosity combined with magnetic functionality of the secondary nanostructures has facilitated efficient heavy metal (As, Cu and Cd) remediation from water solution within a short period of contact time. It is because of the larger surface area of MFSNs due to the porous network in addition to primary nanostructures which provides abundant adsorption sites facilitating high adsorption of the heavy metal ions. The brilliance of adsorption property of MFSNs has been realized through comprehensive adsorption studies and detailed kinetics. Due to their larger dimension, MFSNs help in overcoming the Brownian motion which facilitates easy separation of the metal ion sorbed secondary nanostructures and also do not get drained out during filtration, thus providing pure water.

  16. Mesoporous magnetic secondary nanostructures as versatile adsorbent for efficient scavenging of heavy metals.

    PubMed

    Bhattacharya, Kakoli; Parasar, Devaborniny; Mondal, Bholanath; Deb, Pritam

    2015-01-01

    Porous magnetic secondary nanostructures exhibit high surface area because of the presence of plentiful interparticle spaces or pores. Mesoporous Fe3O4 secondary nanostructures (MFSNs) have been studied here as versatile adsorbent for heavy metal scavenging. The porosity combined with magnetic functionality of the secondary nanostructures has facilitated efficient heavy metal (As, Cu and Cd) remediation from water solution within a short period of contact time. It is because of the larger surface area of MFSNs due to the porous network in addition to primary nanostructures which provides abundant adsorption sites facilitating high adsorption of the heavy metal ions. The brilliance of adsorption property of MFSNs has been realized through comprehensive adsorption studies and detailed kinetics. Due to their larger dimension, MFSNs help in overcoming the Brownian motion which facilitates easy separation of the metal ion sorbed secondary nanostructures and also do not get drained out during filtration, thus providing pure water. PMID:26602613

  17. Upregulations of metallothionein gene expressions and tolerance to heavy metal toxicity by three dimensional cultivation of HepG2 cells on VECELL 3-D inserts.

    PubMed

    Kubo, Takashi; Kuroda, Yukie; Horiuchi, Shinichiro; Kim, Su-Ryang; Sekino, Yuko; Ishida, Seiichi

    2016-02-01

    The VECELL 3-D insert is a new culture scaffold consisting of collagen-coated ePTFE (expanded polytetrafluoroethylene) mesh. We analyzed the effects of VECELL 3-D inserts on the functionality of HepG2, a human hepatocellular carcinoma cell line. HepG2 cells cultured on VECELL 3-D inserts maintained a round shape, while those cultured on a standard culture plate or collagen-coated cell culture plate showed a flattened and cubic epithelial-like shape. HepG2 cells cultured on VECELL 3-D inserts had showed upregulated expression of metallothionein genes and in turn a higher tolerance to toxicity induced by heavy metals. These results suggest that HepG2 cell functions were changed by the cell morphology that is induced by culturing on a VECELL 3-D insert. PMID:26763402

  18. Patterning process exploration of metal 1 layer in 7nm node with 3D patterning flow simulations

    NASA Astrophysics Data System (ADS)

    Gao, Weimin; Ciofi, Ivan; Saad, Yves; Matagne, Philippe; Bachmann, Michael; Oulmane, Mohamed; Gillijns, Werner; Lucas, Kevin; Demmerle, Wolfgang; Schmoeller, Thomas

    2015-03-01

    In 7mn node (N7), the logic design requires the critical poly pitch (CPP) of 42-45nm and metal 1 (M1) pitch of 28- 32nm. Such high pattern density pushes the 193 immersion lithography solution toward its limit and also brings extremely complex patterning scenarios. The N7 M1 layer may require a self-aligned quadruple patterning (SAQP) with triple litho-etch (LE3) block process. Therefore, the whole patterning process flow requires multiple exposure+etch+deposition processes and each step introduces a particular impact on the pattern profiles and the topography. In this study, we have successfully integrated a simulation tool that enables emulation of the whole patterning flow with realistic process-dependent 3D profile and topology. We use this tool to study the patterning process variations of N7 M1 layer including the overlay control, the critical dimension uniformity (CDU) budget and the lithographic process window (PW). The resulting 3D pattern structure can be used to optimize the process flow, verify design rules, extract parasitics, and most importantly, simulate the electric field and identify hot spots for dielectric reliability. As an example application, we will report extractions of maximum electric field at M1 tipto- tip which is one of the most critical patterning locations and we will demonstrate the potential of this approach for investigating the impact of process variations on dielectric reliability. We will also present simulations of an alternative M1 patterning flow, with a single exposure block using extreme ultraviolet lithography (EUVL) and analyze its advantages compared to the LE3 block approach.

  19. Solving the nanostructure problem: exemplified on metallic alloy nanoparticles

    NASA Astrophysics Data System (ADS)

    Petkov, Valeri; Prasai, Binay; Ren, Yang; Shan, Shiyao; Luo, Jin; Joseph, Pharrah; Zhong, Chuan-Jian

    2014-08-01

    With current technology moving rapidly toward smaller scales nanometer-size materials, hereafter called nanometer-size particles (NPs), are being produced in increasing numbers and explored for various useful applications ranging from photonics and catalysis to detoxification of wastewater and cancer therapy. Nature also is a prolific producer of useful NPs. Evidence can be found in ores on the ocean floor, minerals and soils on land and in the human body that, when water is excluded, is mostly made of proteins that are 6-10 nm in size and globular in shape. Precise knowledge of the 3D atomic-scale structure, that is how atoms are arranged in space, is a crucial prerequisite for understanding and so gaining more control over the properties of any material, including NPs. In the case of bulk materials such knowledge is fairly easy to obtain by Bragg diffraction experiments. Determining the 3D atomic-scale structure of NPs is, however, still problematic spelling trouble for science and technology at the nanoscale. Here we explore this so-called ``nanostructure problem'' from a practical point of view arguing that it can be solved when its technical, that is the inapplicability of Bragg diffraction to NPs, and fundamental, that is the incompatibility of traditional crystallography with NPs, aspects are both addressed properly. As evidence we present a successful and broadly applicable, 6-step approach to determining the 3D atomic-scale structure of NPs based on a suitable combination of a few experimental and computational techniques. This approach is exemplified on 5 nm sized PdxNi100-x particles (x = 26, 56 and 88) explored for catalytic applications. Furthermore, we show how once an NP atomic structure is determined precisely, a strategy for improving NP structure-dependent properties of particular interest to science and technology can be designed rationally and not subjectively as frequently done now.With current technology moving rapidly toward smaller scales

  20. Multidimensional (0D to 3D) Alkaline-Earth Metal Diphosphonates: Synthesis, Structural Diversity, and Luminescence Properties.

    PubMed

    Senthil Raja, Duraisamy; Lin, Pin-Chun; Liu, Wei-Ren; Zhan, Jun-Xiang; Fu, Xin-Yi; Lin, Chia-Her

    2015-05-01

    A series of new alkaline-earth metal diphosphonate frameworks were successfully synthesized under solvothermal reaction condition (160 °C, 3 d) using 1-hydroxyethylidene-1,1-diphosphonic acid (CH3C(OH)(H2PO3)2, hedpH4) as a diphosphonate building block and Mg(II), Ca(II), Sr(II), or Ba(II) ions as alkaline-earth metal ion centers in water, dimethylformamide, and/or EtOH media. These diphosphonate frameworks, (H2NMe2)4[Mg(hedpH2)3]·3H2O (1), (H2NMe2)2[Ca(hedpH2)2] (2), (H2NMe2)2[Sr3(hedpH2)4(H2O)2] (3), and [Ba3(hedpH2)3]·H2O (4) exhibited interesting structural topologies (zero-, one-, two-, and three-dimensional (0D, 1D, 2D, and 3D, respectively)), which are mainly depending on the metal ions and the solvents used in the synthesis. The single-crystal analysis of these newly synthesized compounds revealed that 1 was a 0D molecule, 2 has 1D chains, 3 was a 3D molecule, and 4 has 2D layers. All compounds were further characterized using thermogravimetric analysis, solid-state (31)P NMR, powder X-ray diffraction analysis, UV-vis spectra, and infrared spectroscopy. In addition, Eu(III)- and Tb(III)-doped compounds of 1-4, namely, (H2NMe2)4[Ln(x)Mg(1-x)(hedpH2)2(hedpH(2-x))]·3H2O (1Ln), (H2NMe2)2[Ln(x)Ca(1-x)(hedpH2)(hedpH(2-x))] (2Ln), (H2NMe2)2[Ln(x)Sr(3-x)(hedpH2)3(hedpH(2-x))(H2O)2] (3Ln), and [Ln(x)Ba(3-x)(hedpH2)2(hedpH(2-x))]·H2O (4Ln) (where Ln = Eu, Tb), were synthesized, and their photoluminescence properties were studied. The quantum yield of 1Eu-4Eu was measured with reference to commercial red phosphor, Y2O2S:Eu(3+) (YE), and the quantum yield of terbium-doped compounds 1Tb-4Tb was measured with reference to commercial green-emitting phosphor CeMgAl10O17:Tb(3+). Interestingly, the compound 2Eu showed very high quantum yield of 92.2%, which is better than that of the reference commercial red phosphor, YE (90.8%). PMID:25871285

  1. Design, synthesis, and optimization of nanostructured calcium phosphates (NanoCaPs) and natural polymer based 3-D non-viral gene delivery systems

    NASA Astrophysics Data System (ADS)

    Ko, Hsu-Feng

    Sustained delivery of therapeutic genes from a three-dimensional (3-D) scaffold and subsequent gene expression capable of triggering the regeneration of damaged tissues is a tissue engineering strategy that has been gaining increased attention. Nanostructured calcium phosphates (NanoCaPs) are biocompatible and non-toxic biomaterials. Furthermore, their efficient transfection in vitro have rendered them attractive gene delivery carriers compared to other viral- or lipid-based agents that tend to be immunogenic or cytotoxic, leading to undesirable responses when utilized above a critical threshold. However, NanoCaPs are typically characterized by variable transfection and short shelf life due to particle aggregation. A viable solution to this problem is the incorporation of NanoCaPs into 3-D scaffolds. The main objectives of this research are therefore two-fold: (1) Examination of the potential of achieving optimized transfection of NanoCaPs via anionic substitution and (2) high throughput synthesis and screening of non-viral gene delivery systems (GDS) comprised of naturally-derived polymers as scaffolds containing NanoCaPs gene carriers. Results indicated that in addition to the excellent transfection levels exhibited by NanoCaPs in vitro, an additional 20-30% increase was observed for NanoCaPs with 10-25 mol% anion substitution. In contrast, high anion substitution (>60%) yielded a drastic decline in transfection. Structural characterizations verified successful anion substitution with a noticeable increase in lattice parameters indicative of an expanded unit cell due to ionic substitution. All of the anion substituted calcium phosphates exhibited the primary phase of hydroxyapatite. For the first time, GDS composed of various concentrations of alginate (AA), fibronectin (FN), and NanoCaPs-DNA complexes were demonstrated. The presence of AA and FN was effective in immobilizing NanoCaPs and reducing the aggregation. High throughput synthesis and screening

  2. Nanostructure operations by means of the liquid metal ion sourcesa)

    NASA Astrophysics Data System (ADS)

    Gasanov, I. S.; Gurbanov, I. I.

    2012-02-01

    Characteristics of a disperse phase of liquid metal ion source on the basis of various working substances are investigated. It is revealed that generation of the charged particles occurs in the threshold image and is simultaneously accompanied by excitation of capillary instability on a surface of the emitter. The majority of particles has the size about 2 nm (Sn) and a specific charge of 5 × 104 C/kg. If the working liquid possesses high viscosity (Ni), generation of nanodroplets does not occur. Gold nanoparticles are used for deposition on a surface of quartz cantilevers with the purpose of increase in sensitivity of biosensors and on an external surface of carbon nanotubes for creation pressure sensors. By means of an ion source nanostructures can be etched on a flat surface of conductive materials without difficult ion optics.

  3. Cell responses to metallic nanostructure arrays with complex geometries.

    PubMed

    Jahed, Zeinab; Molladavoodi, Sara; Seo, Brandon B; Gorbet, Maud; Tsui, Ting Y; Mofrad, Mohammad R K

    2014-11-01

    Metallic nanopillar/nanowires are emerging as promising platforms for biological applications, as they allow for the direct characterization and regulation of cell function. Herein we study the response of cells to a versatile nanopillar platform. Nanopillar arrays of various shape, size, and spacing and different nanopillar-substrate interfacial strengths were fabricated and interfaced with fibroblasts and several unique cell-nanopillar interactions were observed using high resolution scanning electron microscopy. Nanopillar penetration, engulfment, tilting, lift off and membrane thinning, were observed by manipulating nanopillar material, size, shape and spacing. These unique cell responses to various nanostructures can be employed for a wide range of applications including the design of highly sensitive nano-electrodes for single-cell probing. PMID:25123921

  4. High-speed photocathodes fabricated from metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Nolle, Eduard L.; Khavin, Yuri B.; Schelev, Mikhail Y.

    2005-03-01

    Spectral dependences of photoemission (PE), absorption and reflection from Ag and Au granular films are studied experimentally together with their structure and physical properties using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPES). It is found that a new intensive PE band in the visible spectral range (l = 500 - 600 nm) appears when such films are activated with Cs and O and this PE band coincides with the absorption and reflection bands. Theoretical calculations of PE spectra based on absorption spectrum of metallic oblate spheroidal nanoparticles are also carried out. Such calculations indicate that the appearance of this PE band can be explained by excitation of the surface plasmons in spheroidal nanoparticles with the major axes approximately equal to 50 nm and minor axes approximately equal to 5 nm. Similar calculations carried out for an S-1 photocathode indicate that the shape and the position of the measured long wavelength PE band with the peak maximum at λ ~ 800 nm can also be explained by excitation of the surface plasmons in Ag spheroidal nanoparticles with the axes equal to 25 and 0.9 nm correspondingly. Degradation with time of PE from Ag and Au granular films is also studied and it is shown that while Ag nanoparticles degrade due to desorption of Cs, Au nanoparticles degrade due to its adsorption. Photoelectron emission in the studied metallic nanostructures can be explained by the surface photoeffect caused by excitation of the surface plasmons in nanoparticles. Therefore, photocathodes with subfemtosecond-range temporal resolution and quantum yield equal to several percent in the visible wavelength range can be fabricated from such nanostructures.

  5. Formation of oriented nanostructures in diamond using metallic nanoparticles.

    PubMed

    Mehedi, H-A; Hebert, C; Ruffinatto, S; Eon, D; Omnes, F; Gheeraert, E

    2012-11-16

    A simple, fast and cost-effective etching technique to create oriented nanostructures such as pyramidal and cylindrical shaped nanopores in diamond membranes by self-assembled metallic nanoparticles is proposed. In this process, a diamond film is annealed with thin metallic layers in a hydrogen atmosphere. Carbon from the diamond surface is dissolved into nanoparticles generated from the metal film, then evacuated in the form of hydrocarbons and, consequently, the nanoparticles enter the crystal volume. In order to understand and optimize the etching process, the role of different parameters such as type of catalyst (Ni, Co, Pt, and Au), hydrogen gas, temperature and time of annealing, and microstructure of diamond (polycrystalline and nanocrystalline) were investigated. With this technique, nanopores with lateral sizes in the range of 10-100 nm, and as deep as about 600 nm, in diamond membranes were produced without any need for a lithography process, which opens the opportunities for fabricating porous diamond membranes for chemical sensing applications. PMID:23090452

  6. Plasmonic nanostructured metal-oxide-semiconductor reflection modulators.

    PubMed

    Olivieri, Anthony; Chen, Chengkun; Hassan, Sa'ad; Lisicka-Skrzek, Ewa; Tait, R Niall; Berini, Pierre

    2015-04-01

    We propose a plasmonic surface that produces an electrically controlled reflectance as a high-speed intensity modulator. The device is conceived as a metal-oxide-semiconductor capacitor on silicon with its metal structured as a thin patch bearing a contiguous nanoscale grating. The metal structure serves multiple functions as a driving electrode and as a grating coupler for perpendicularly incident p-polarized light to surface plasmons supported by the patch. Modulation is produced by charging and discharging the capacitor and exploiting the carrier refraction effect in silicon along with the high sensitivity of strongly confined surface plasmons to index perturbations. The area of the modulator is set by the area of the incident beam, leading to a very compact device for a strongly focused beam (∼2.5 μm in diameter). Theoretically, the modulator can operate over a broad electrical bandwidth (tens of gigahertz) with a modulation depth of 3 to 6%, a loss of 3 to 4 dB, and an optical bandwidth of about 50 nm. About 1000 modulators can be integrated over a 50 mm(2) area producing an aggregate electro-optic modulation rate in excess of 1 Tb/s. We demonstrate experimentally modulators operating at telecommunications wavelengths, fabricated as nanostructured Au/HfO2/p-Si capacitors. The modulators break conceptually from waveguide-based devices and belong to the same class of devices as surface photodetectors and vertical cavity surface-emitting lasers. PMID:25730698

  7. Ultrafine and Smooth Full Metal Nanostructures for Plasmonics

    NASA Astrophysics Data System (ADS)

    Zhu, Xinli; Zhang, Jaseng; Xu, Jun; Liao, Zhimin; Wu, Xiaosong; Yu, Dapeng

    2013-03-01

    Surface plasmon polaritons (SPPs), which are coupled excitations of electrons bound to a metal-dielectric interface, show great potential for application in future nanoscale photonic systems due to the strong field confinement at the nanoscale, intensive local field enhancement, and interplay between strongly localized and propagating SPPs. The fabrication of sufficiently smooth metal surface with nanoscale feature size is crucial for SPPs to have practical applications. A template stripping (ST) method combined with PMMA as a template was successfully developed to create extraordinarily smooth metal nanostructures with a desirable feature size and morphology for plasmonics and metamaterials. The advantages of this method, including the high resolution, precipitous top-to bottom profile with a high aspect ratio, and three-dimensional characteristics, make it very suitable for the fabrication of plasmonic structures. By using this ST method, boxing ring-shaped nanocavities have been fabricated and the confined modes of surface plasmon polaritons in these nanocavities have been investigated and imaged by using cathodoluminescence spectroscopy. The mode of the out-of-plane field components of surface plasmon polaritons dominates the experimental mode patterns, indicating that the electron beam locally excites the out-of-plane field component of surface plasmon polaritons, and quality factors can be directly acquired. Numerous applications, such as plasmonic filter, nanolaser, and efficient light-emitting devices, can be expected to arise from these developments.

  8. Local structures around 3d metal dopants in topological insulator Bi2Se3 studied by EXAFS measurements

    NASA Astrophysics Data System (ADS)

    Liu, Zhen; Wei, Xinyuan; Wang, Jiajia; Pan, Hong; Ji, Fuhao; Xi, Fuchun; Zhang, Jing; Hu, Tiandou; Zhang, Shuo; Jiang, Zheng; Wen, Wen; Huang, Yuying; Ye, Mao; Yang, Zhongqin; Qiao, Shan

    2014-09-01

    Transition-metal-doped Bi2Se3 crystals, X0.05Bi2Se3 (X =Cr, Co, Ni, and Cu), are prepared and studied by powder x-ray diffraction and extended x-ray absorption fine structure (EXAFS) measurements to get the local structures around the dopants. Cr atoms substitute Bi atoms and Co atoms may substitute Bi atoms or form Co3Se4 (C2/m) clusters. Cu is also found taking the Bi substitutional site, which differs from the reported superconductor phase of Cu-doped Bi2Se3, suggesting the dependence of site occupancy of Cu in Bi2Se3 on the process of sample growing. For Ni0.05Bi2Se3, Ni atoms form Ni3Se4 (C2/m) clusters. The nearest neighbors of X (X =Cr, Co, and Cu) are Se atoms, and the X-Se bond lengths are extracted from EXAFS as 2.50 Å for Cr-Se, 2.40 Å for Co-Se, and 2.38 Å for Cu-Se, which show the direct evidences of dramatic structural relaxations around 3d dopants. The bond information of local structures around dopants is valuable for subsequent theoretical studies, and can hardly be obtained from other techniques.

  9. A full 3D model of fluid flow and heat transfer in an E.B. heated liquid metal bath

    NASA Astrophysics Data System (ADS)

    Matveichev, A.; Jardy, A.; Bellot, J. P.

    2016-07-01

    In order to study the dissolution of exogeneous inclusions in the liquid metal during processing of titanium alloys, a series of dipping experiments has been performed in an Electron Beam Melting laboratory furnace. Precise determination of the dissolution kinetics requires knowing and mastering the exact thermohydrodynamic behavior of the melt pool, which implies full 3D modeling of the process. To achieve this goal, one needs to describe momentum and heat transfer, phase change, as well as the development of flow turbulence in the liquid. EB power input, thermal radiation, heat loss through the cooling circuit, surface tension effects (i.e. Marangoni-induced flow) must also be addressed in the model. Therefore a new solver dealing with all these phenomena was implemented within OpenFOAM platform. Numerical results were compared with experimental data from actual Ti melting, showing a pretty good agreement. In the second stage, the immersion of a refractory sample rod in the liquid pool was simulated. Results of the simulations showed that the introduction of the sample slightly disturbs the flow field inside the bath. The amount of such disturbance depends on the exact location of the dipping.

  10. Positional isomerism-driven two 3D pillar-layered metal-organic frameworks: Syntheses, topological structures and photoluminescence properties

    NASA Astrophysics Data System (ADS)

    Sun, Yayong; Zhao, Siwei; Ma, Haoran; Han, Yi; Liu, Kang; Wang, Lei

    2016-06-01

    Two novel three-dimensional (3D) pillar-layered metal-organic frameworks (MOFs), namely [Zn2(μ2-OH)(boaba)(1,4-bmimb)]n (1) and {[Zn5K2(μ2-H2O)2(boaba)4(1,2-bmimb)2(H2O)2]·H2O}n (2), were prepared by hydrothermal reactions (H3boaba=3,5-bis-oxyacetate-benzoic acid; 1,4-bmimb=1,4-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene; 1,2-bmimb =1,2-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene). Notably, 1 exhibits a (3,5)-connected binodal (63)(69·8)-gra net with binuclear [Zn2(μ2-OH)(COO)]2+ clusters, while 2 shows a novel (4,4,5,9)-connected 4-nodal net constructed from the unique Zn(II)-K(I) heterometal rod-like substructures. The results indicate that the disposition of the 2-methylimidazolyl groups of bis(imidazole) ligands have a significant effect on structural diversity. Moreover, the photoluminescence properties of 1 and 2 have been investigated.

  11. First-principles study of magnetic interactions in 3d transition metal-doped phase-change materials

    NASA Astrophysics Data System (ADS)

    Fukushima, T.; Katayama-Yoshida, H.; Sato, K.; Fujii, H.; Rabel, E.; Zeller, R.; Dederichs, P. H.; Zhang, W.; Mazzarello, R.

    2014-10-01

    Recently, magnetic phase-change materials have been synthesized experimentally by doping with 3d transition metal impurities. Here, we investigate the electronic structure and the magnetic properties of the prototypical phase-change material Ge2Sb2Te5 (GST) doped with V, Cr, Mn, and Fe by density functional calculations. Both the supercell method and the coherent potential approximation (CPA) are employed to describe this complex substitutionally disordered system. As regards the first approach, we consider a large unit cell containing 1000 sites to model the random distribution of the cations and of the impurities in doped cubic GST. Such a large-scale electronic structure calculation is performed using the program kkrnano, where the full potential screened Korringa-Kohn-Rostoker Green's function method is optimized by a massively parallel linear scaling (order-N) all-electron algorithm. Overall, the electronic structures and magnetic exchange coupling constants calculated by kkrnano agree quite well with the CPA results. We find that ferromagnetic states are favorable in the cases of V and Cr doping, due to the double exchange mechanism, whereas antiferromagnetic superexchange interactions appear to be dominant for Fe- and Mn-doped GST. The ferromagnetic interaction is particularly strong in the case of Cr. As a result, high Curie temperatures close to room temperatures are obtained for large Cr concentrations of 15%.

  12. Electronic and magnetic properties of monolayer SiC sheet doped with 3d-transition metals

    NASA Astrophysics Data System (ADS)

    Bezi Javan, Masoud

    2016-03-01

    We theoretically studied the electronic and magnetic properties of the monolayer SiC sheet doped by 3d transition-metal (TM) atoms. The structural properties, induced strain, electronic and magnetic properties were studied for cases that a carbon or silicon of the SiC sheet replaced with TM atoms. We found that the mount of induced strain to the lattice structure of the SiC sheet with substituting TM atoms is different for Si (TMSi) and C (TMC) sites as the TMSi structures have lower value of the strain. Also the TM atoms can be substituted in the lattice of the SiC sheet with different binding energy values for TMSi and TMC structures as the TMSi structures have higher value of the binding energies. Dependent to the structural properties, the TM doped SiC sheets show magnetic or nonmagnetic properties. We found that some structures such as MnSi, CuSi and CoC configurations have significant total magnetic moment about 3 μB.

  13. First-principle study of the electronic structure and magnetism of lithium-adsorbed 3d transition-metal phthalocyanines

    NASA Astrophysics Data System (ADS)

    Wang, M.; Hu, Y.; Zhang, Z.; Li, Y.; Zhou, T.; Ren, J.

    2016-02-01

    Based on density functional theory (DFT) calculations, the electronic structures and magnetic properties of 3d transition-metal phthalocyanine (TMPc, TM = Ti, V, Cr, Mn, Fe, Co, Ni and Cu), as well as Li-adsorbed phthalocyanines have been studied. The results show that the pristine TMPcs all have a good D4h symmetry. When there is one Li atom adsorbed on TMPcs directly over (LiTMPc-α) or slantly above (LiTMPc-β) the TM atoms, the geometries and electronic structures will be changed. For LiTMPc-α systems, the central TM atoms will deviate from the molecular plane and the molecules exhibit good C4v symmetry. LiTMPc-β systems are more stable than LiTMPc-α systems but it do not possess D4h and C4v symmetries. The total and local magnetic moments and the charge transfer are also presented. Finally, by using the orbit mixing and splitting theory under D4h and C4v symmetry, we get the ordering of the energy levels of the central TM atoms.

  14. Effect of 3d-transition metal doping on the shielding behavior of barium borate glasses: a spectroscopic study.

    PubMed

    ElBatal, H A; Abdelghany, A M; Ghoneim, N A; ElBatal, F H

    2014-12-10

    UV-visible and FT infrared spectra were measured for prepared samples before and after gamma irradiation. Base undoped barium borate glass of the basic composition (BaO 40%-B2O3 60mol.%) reveals strong charge transfer UV absorption bands which are related to unavoidable trace iron impurities (Fe(3+)) within the chemical raw materials. 3d transition metal (TM)-doped glasses exhibit extra characteristic absorption bands due to each TM in its specific valence or coordinate state. The optical spectra show that TM ions favor generally the presence in the high valence or tetrahedral coordination state in barium borate host glass. Infrared absorption bands of all prepared glasses reveal the appearance of both triangular BO3 units and tetrahedral BO4 units within their characteristic vibrational modes and the TM-ions cause minor effects because of the low doping level introduced (0.2%). Gamma irradiation of the undoped barium borate glass increases the intensity of the UV absorption together with the generation of an induced broad visible band at about 580nm. These changes are correlated with suggested photochemical reactions of trace iron impurities together with the generation of positive hole center (BHC or OHC) within the visible region through generated electrons and positive holes during the irradiation process. PMID:24983922

  15. First-principles study of nitric oxide oxidation on Pt(111) versus Pt overlayer on 3d transition metals

    SciTech Connect

    Arevalo, Ryan Lacdao; Escaño, Mary Clare Sison; Kasai, Hideaki

    2015-03-15

    Catalytic oxidation of NO to NO{sub 2} is a significant research interest for improving the quality of air through exhaust gas purification systems. In this paper, the authors studied this reaction on pure Pt and Pt overlayer on 3d transition metals using kinetic Monte Carlo simulations coupled with density functional theory based first principles calculations. The authors found that on the Pt(111) surface, NO oxidation proceeds via the Eley–Rideal mechanism, with O{sub 2} dissociative adsorption as the rate-determining step. The oxidation path via the Langmuir–Hinshelwood mechanism is very slow and does not significantly contribute to the overall reaction. However, in the Pt overlayer systems, the oxidation of NO on the surface is more thermodynamically and kinetically favorable compared to pure Pt. These findings are attributed to the weaker binding of O and NO on the Pt overlayer systems and the binding configuration of NO{sub 2} that promotes easier N-O bond formation. These results present insights for designing affordable and efficient catalysts for NO oxidation.

  16. Effects of 3d and 4d transition metal substitutional impurities on the electronic properties of CrO2

    NASA Astrophysics Data System (ADS)

    Williams, M. E.; Sims, H.; Mazumdar, D.; Butler, W. H.

    2012-12-01

    We present first-principles-based density functional theory calculations of the electronic and magnetic structure of CrO2 with 3d and 4d substitutional impurities. We find that the half-metallicity of CrO2 remains intact for the ground state of all of the calculated substitutions. We also observe two periodic trends as a function of the number of valence electrons: if the substituted atom has six or fewer valence electrons, the number of down spin electrons associated with the impurity ion is zero, resulting in ferromagnetic alignment of the impurity magnetic moment with the magnetization of the CrO2 host. For substituent atoms with eight to ten valence electrons (with the exception of Ni), the number of down-spin electrons contributed by the impurity ion remains fixed at three as the number contributed to the majority increases from one to three resulting in antiferromagnetic alignment between impurity moment and host magnetization. In impurities with seven valence electrons, the zero down-spin and threse down-spin configurations are very close in energy. At 11 valence electrons, the energy is minimized when the substituent ion contributes five down-spin electrons. The moments on the 4d impurities, particularly Nb and Mo, tend to be delocalized compared with those of the 3ds.

  17. Formation of metallic nanostructures on the surface of ion- exchange glass by focused electron beam

    NASA Astrophysics Data System (ADS)

    Komissarenko, F. E.; Zhukov, M. V.; Mukhin, I. S.; Golubok, A. O.; Sidorov, A. I.

    2015-11-01

    This paper presents a new method for formation of metallic nanostructures on the surface of ion-exchange glass. The method is based on the interaction of a focused electron beam with ions in ion-exchange glass. In experiments nanostructures with different shapes were obtained, depending on the electrons irradiation conditions.

  18. Enhanced near-infrared absorption in graphene with multilayer metal-dielectric-metal nanostructure.

    PubMed

    Zhang, Lei; Tang, Linlong; Wei, Wei; Cheng, Xinlu; Wang, Wei; Zhang, Hong

    2016-09-01

    A multilayer metal-dielectric-metal nanostructure is proposed to enhance the absorption in graphene in a near-infrared region. The main feature of the structure is the generation of strong magnetic response within the dielectric spacer, which is directly related to absorption enhancement in graphene to over 22 times higher than that of free-standing monolayer graphene. We also show that absorption enhancement in graphene can be easily controlled by adjusting the geometry of the propose structure. The simple structural configuration and the flexible tunability in absorption enhancement are beneficial for practical fabrication and future applications in graphene-based active optoelectronic devices. PMID:27607608

  19. Sustainable synthesis, characterization, and applications of metal oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Tiano, Amanda Lyn

    Nanomaterials have attracted significant research focus due to their advantageous and unique properties (i.e. electronic, magnetic, optical, and mechanical) as compared with the bulk. Metal oxide nanostructures are of particular interest, as they are very robust and display high chemical and thermal stability, while offering a diverse array of fascinating properties. By reliably controlling the size, morphology, composition, and crystallinity of these nanostructures, their properties can be tuned for a specific purpose. These advantageous tailorable properties render them as ideal candidates for many applications such as catalysis, sensing, electronics, optoelectronics, energy storage, and even medicine. Driven by their increased popularity and potential applications, efforts to synthesize nanomaterials have moved toward environmentally-friendly methodologies, such as wet-chemical, molten-salt, hydrothermal, and sol-gel methods. We will discuss the green synthesis of strontium ruthenate (SrRuO 3), the yttrium manganese oxides (YMnO3 and YMn2O 5), and the magnetic spinel ferrites (MFe2O4 where 'M' is Mg, Fe, Co, Ni, Cu, and Zn) and our ability to reliably tune their properties for various applications. The effects of the molten salt parameters on the resulting particle size and morphology were explored for SrRuO 3 and the yttrium manganese oxides. For example, rapid cooling rates and the use of surfactants allowed us to produced faceted octahedra of SrRuO 3, which resulted in a 4-fold enhancement of their activity towards methanol oxidation with respect to smooth rounded particles. Similarly, using the hydrothermal method, we generated ferrite nanoparticles of different compositions and sizes. We investigated their potential as contrast agents for magnetic resonance imaging (MRI) and as photocatalysts, and observed significant differences as a function of both size and composition. Similarly, we will also examine surface and structural effects upon the electronic

  20. Antiferromagnetic half metallicity in codoped chalcopyrite semiconductors Cu(Al 1 - 2 xAxBx)Se2 (A and B are 3d transition-metal atoms)

    NASA Astrophysics Data System (ADS)

    Shahjahan, M.; Oguchi, T.

    2016-06-01

    Electronic structures and magnetic properties of group I-III-VI2 chalcopyrite-type compounds Cu(Al 1 - 2 xAxBx)Se2 are calculated using the Korringa-Kohn-Rostoker Green's function method, where A (Ti, V, Cr, Mn) and B (Fe, Co, Ni) are 3d transition metal atoms, and x is atomic concentration. We found that codoping of Cr-Co and V-Ni pairs at Al site of host CuAlSe2 exhibit antiferromagnetic (AF) half metallicity with low Curie temperature (TC). The AF half metallic property is supported by nullified net magnetic moment and compensated density of states in the minority spin direction. On the other hand, codoping of Cr-Ni, Mn-Co, V-Co, and Ti-Co pairs at Al site of host CuAlSe2 manifest ferrimagnetic half metallicity with a small net magnetization and keeping antiparallel local spin moments. In Mn-Co case TC is close to room temperature. Besides, Cr-Fe, V-Fe, and Ti-Ni codoping cases lead to an instable magnetic ordering and therefore obtain a disordered local moment (spin-glass like) state.

  1. A Comprehensive Review of One-Dimensional Metal-Oxide Nanostructure Photodetectors

    PubMed Central

    Zhai, Tianyou; Fang, Xiaosheng; Liao, Meiyong; Xu, Xijin; Zeng, Haibo; Yoshio, Bando; Golberg, Dmitri

    2009-01-01

    One-dimensional (1D) metal-oxide nanostructures are ideal systems for exploring a large number of novel phenomena at the nanoscale and investigating size and dimensionality dependence of nanostructure properties for potential applications. The construction and integration of photodetectors or optical switches based on such nanostructures with tailored geometries have rapidly advanced in recent years. Active 1D nanostructure photodetector elements can be configured either as resistors whose conductions are altered by a charge-transfer process or as field-effect transistors (FET) whose properties can be controlled by applying appropriate potentials onto the gates. Functionalizing the structure surfaces offers another avenue for expanding the sensor capabilities. This article provides a comprehensive review on the state-of-the-art research activities in the photodetector field. It mainly focuses on the metal oxide 1D nanostructures such as ZnO, SnO2, Cu2O, Ga2O3, Fe2O3, In2O3, CdO, CeO2, and their photoresponses. The review begins with a survey of quasi 1D metal-oxide semiconductor nanostructures and the photodetector principle, then shows the recent progresses on several kinds of important metal-oxide nanostructures and their photoresponses and briefly presents some additional prospective metal-oxide 1D nanomaterials. Finally, the review is concluded with some perspectives and outlook on the future developments in this area. PMID:22454597

  2. A Comprehensive Review of Glucose Biosensors Based on Nanostructured Metal-Oxides

    PubMed Central

    Rahman, Md. Mahbubur; Saleh Ahammad, A. J.; Jin, Joon-Hyung; Ahn, Sang Jung; Lee, Jae-Joon

    2010-01-01

    Nanotechnology has opened new and exhilarating opportunities for exploring glucose biosensing applications of the newly prepared nanostructured materials. Nanostructured metal-oxides have been extensively explored to develop biosensors with high sensitivity, fast response times, and stability for the determination of glucose by electrochemical oxidation. This article concentrates mainly on the development of different nanostructured metal-oxide [such as ZnO, Cu(I)/(II) oxides, MnO2, TiO2, CeO2, SiO2, ZrO2, and other metal-oxides] based glucose biosensors. Additionally, we devote our attention to the operating principles (i.e., potentiometric, amperometric, impedimetric and conductometric) of these nanostructured metal-oxide based glucose sensors. Finally, this review concludes with a personal prospective and some challenges of these nanoscaled sensors. PMID:22399911

  3. Large-scale fabrication of flexible metallic nanostructure pairs using interference ablation.

    PubMed

    Zhai, Tianrui; Wang, Yonglu; Liu, Hongmei; Zhang, Xinping

    2015-01-26

    Paired one- and two-dimensional metallic nanostructures are created directly by exposing a thin gold film to the interference pattern between ultraviolet laser pulses, where the gold film is coated onto a soft substrate and is sandwiched by another soft slab. Metallic films in the bright fringes are melted and transformed into nanodroplets that are ejected onto the soft slab forming stretchable nanoisland structures. The pattern of the remaining films is coincident with the dark fringes. Thus, complementary metallic nanostructure pairs were fabricated using a single laser pulse. Fano resonance can be observed in the spectroscopic response of the fabricated nanostructures for TM and TE polarizations simultaneously. This nanofabrication technique may provide an annealing-free approach for the fabrication of flexible metallic nanostructures on a large scale and with low cost. PMID:25835940

  4. GREENER PRODUCTION OF NOBLE METAL NANOSTRUCTURES AND NANOCOMPOSITES: RISK REDUCTION AND APPLICATIONS

    EPA Science Inventory

    The synthesis of nanometal/nano metal oxide/nanostructured polymer and their stabilization (through dispersant, biodegradable polymer) involves the use of natural renewable resources such plant material extract, biodegradable polymers, sugars, vitamins and finally efficient and s...

  5. 3D finite element analysis of a metallic sphere scatterer comparison of first and second order vector absorbing boundary conditions

    NASA Astrophysics Data System (ADS)

    Kanellopoulos, V. N.; Webb, J. P.

    1993-03-01

    A 3D vector analysis of plane wave scattering by a metallic sphere using finite elements and Absorbing Boundary Conditions (ABCs) is presented. The ABCs are applied on the outer surface that truncates the infinitely extending domain. Mixed order curvilinear covariantprojection elements are used to avoid spurious corruptions. The second order ABC is superior to the first at no extra computational cost. The errors due to incomplete absorption decrease as the outer surface is moved further away from the scatterer. An error of about 1% in near-field values was obtained with the second order ABC, when the outer surface was less than half a wavelength from the scatterer. Une analyse tridimensionnelle vectorielle de la diffusion d'onde plane sur une sphère métallique utilisant des éléments finis et des Conditions aux Limites Absorbantes (CLA) est présentée. Les CLA sont appliquées sur la surface exteme tronquant le domaine s'étendant à l'infini. Des éléments curvilignes mixtes utilisant des projections covariantes sont utilisés pour éviter des solutions parasites. La CLA de second ordre est supérieure à celle de premier ordre sans effort de calcul additionnel. Les erreurs dues à l'absorption incomplète décroissent à mesure que l'on déplace la surface externe à une distance croissante du diffuseur. Un taux d'erreur d'environ 1 % dans les valeurs du champ proche a été obtenu avec les CLA de second ordre lorsque la surface externe était placée à une distance inférieure à une demi-longueur de la source de diffusion.

  6. Organic phase synthesis of noble metal-zinc chalcogenide core-shell nanostructures.

    PubMed

    Kumar, Prashant; Diab, Mahmud; Flomin, Kobi; Rukenstein, Pazit; Mokari, Taleb

    2016-10-15

    Multi-component nanostructures have been attracting tremendous attention due to their ability to form novel materials with unique chemical, optical and physical properties. Development of hybrid nanostructures that are composed of metal-semiconductor components using a simple approach is of interest. Herein, we report a robust and general organic phase synthesis of metal (Au or Ag)-Zinc chalcogenide (ZnS or ZnSe) core-shell nanostructures. This synthetic protocol also enabled the growth of more compositionally complex nanostructures of Au-ZnSxSe1-x alloys and Au-ZnS-ZnSe core-shell-shell. The optical and structural properties of these hybrid nanostructures are also presented. PMID:27428852

  7. Floating AC-DEP (dielectrophoretic) manipulations of fluorescent nanoparticle at metal nanostructure for plasmonic applications

    NASA Astrophysics Data System (ADS)

    Kim, J.; Shin, H. J.; Hwang, K. S.; Park, J. H.

    2014-11-01

    We propose the fluorescent nanoparticle manipulations at nano-metal structures with floating AC-DEP force for plasmonic applications. The electrode gap was optimized to induce enough DEP force around the nano-structure for manipulation of the nanoparticles. 10um wide gap of electrode was acquired to apply the floating AC-DEP force at various designed metal nano-structure such as nanowire, y-branch and vortex. The all shape of nano-metal structures are formed at the gap of microelectrode and not connected with microelectrode. The gold nano-structures in the gap of microelectrode were fabricated with e-beam lithography and lift-off process. Before the formation of metal nanostructure, micro electrodes for applying the electric field around the metal nano-structures were fabricated with photolithography and lift-off process. Cadmium selenide (CdSe/ZnS) QDs (0.8 nM, emission wavelength of 605 nm) with a 25 nm zinc sulfide capping layer and 100nm polystyrene nano bead (1 nM, emission wavelength of 610nm) were used as fluorescent nanoparticles. We applied the 8 Vpp, 3 MHz sine wave for the positive DEP force, and it resulted in 108 V/m electric field and 1011 V/m electric field gradient around gold nanowire with floating AC. The fluorescent nanoparticle's attachment at the nanowire is confirmed by the fluorescent optical analysis. The fluorescent nanoparticles are located successfully at designed metal nano-structures for plasmonic applications.

  8. Metallic nanospheres embedded in nanowires initiated on nanostructures and methods for synthesis thereof

    DOEpatents

    Zaidi, Saleem; Tringe, Joseph W.; Vanamu, Ganesh; Prinja, Rajiv

    2012-01-10

    A nanostructure includes a nanowire having metallic spheres formed therein, the spheres being characterized as having at least one of about a uniform diameter and about a uniform spacing there between. A nanostructure in another embodiment includes a substrate having an area with a nanofeature; and a nanowire extending from the nanofeature, the nanowire having metallic spheres formed therein, the spheres being characterized as having at least one of about a uniform diameter and about a uniform spacing there between. A method for forming a nanostructure is also presented. A method for reading and writing data is also presented. A method for preparing nanoparticles is also presented.

  9. Hybrid nanostructures of metal/two-dimensional nanomaterials for plasmon-enhanced applications.

    PubMed

    Li, Xuanhua; Zhu, Jinmeng; Wei, Bingqing

    2016-06-01

    Hybrid nanostructures composed of graphene or other two-dimensional (2D) nanomaterials and plasmonic metal components have been extensively studied. The unusual properties of 2D materials are associated with their atomically thin thickness and 2D morphology, and many impressive structures enable the metal nanomaterials to establish various interesting hybrid nanostructures with outstanding plasmonic properties. In addition, the hybrid nanostructures display unique optical characteristics that are derived from the close conjunction of plasmonic optical effects and the unique physicochemical properties of 2D materials. More importantly, the hybrid nanostructures show several plasmonic electrical effects including an improved photogeneration rate, efficient carrier transfer, and a plasmon-induced "hot carrier", playing a significant role in enhancing device performance. They have been widely studied for plasmon-enhanced optical signals, photocatalysis, photodetectors (PDs), and solar cells. In this review, the developments in the field of metal/2D hybrid nanostructures are comprehensively described. Preparation of hybrid nanostructures is first presented according to the 2D material type, as well as the metal nanomaterial morphology. The plasmonic properties and the enabled applications of the hybrid nanostructures are then described. Lastly, possible future research in this promising field is discussed. PMID:27048993

  10. Dilute Magnetic Semiconductor and Half-Metal Behaviors in 3d Transition-Metal Doped Black and Blue Phosphorenes: A First-Principles Study.

    PubMed

    Yu, Weiyang; Zhu, Zhili; Niu, Chun-Yao; Li, Chong; Cho, Jun-Hyung; Jia, Yu

    2016-12-01

    We present first-principles density-functional calculations for the structural, electronic, and magnetic properties of substitutional 3d transition metal (TM) impurities in two-dimensional black and blue phosphorenes. We find that the magnetic properties of such substitutional impurities can be understood in terms of a simple model based on the Hund's rule. The TM-doped black phosphorenes with Ti, V, Cr, Mn, Fe, and Ni impurities show dilute magnetic semiconductor (DMS) properties while those with Sc and Co impurities show nonmagnetic properties. On the other hand, the TM-doped blue phosphorenes with V, Cr, Mn, and Fe impurities show DMS properties, with Ni impurity showing half-metal properties, whereas Sc- and Co-doped systems show nonmagnetic properties. We identify two different regimes depending on the occupation of the hybridized electronic states of TM and phosphorous atoms: (i) bonding states are completely empty or filled for Sc- and Co-doped black and blue phosphorenes, leading to nonmagnetic; (ii) non-bonding d states are partially occupied for Ti-, V-, Cr-, Mn-, Fe- and Ni-doped black and blue phosphorenes, giving rise to large and localized spin moments. These results provide a new route for the potential applications of dilute magnetic semiconductor and half-metal in spintronic devices by employing black and blue phosphorenes. PACS numbers: 73.22.-f, 75.50.Pp, 75.75. + a. PMID:26858159

  11. Dilute Magnetic Semiconductor and Half-Metal Behaviors in 3 d Transition-Metal Doped Black and Blue Phosphorenes: A First-Principles Study

    NASA Astrophysics Data System (ADS)

    Yu, Weiyang; Zhu, Zhili; Niu, Chun-Yao; Li, Chong; Cho, Jun-Hyung; Jia, Yu

    2016-02-01

    We present first-principles density-functional calculations for the structural, electronic, and magnetic properties of substitutional 3 d transition metal (TM) impurities in two-dimensional black and blue phosphorenes. We find that the magnetic properties of such substitutional impurities can be understood in terms of a simple model based on the Hund's rule. The TM-doped black phosphorenes with Ti, V, Cr, Mn, Fe, and Ni impurities show dilute magnetic semiconductor (DMS) properties while those with Sc and Co impurities show nonmagnetic properties. On the other hand, the TM-doped blue phosphorenes with V, Cr, Mn, and Fe impurities show DMS properties, with Ni impurity showing half-metal properties, whereas Sc- and Co-doped systems show nonmagnetic properties. We identify two different regimes depending on the occupation of the hybridized electronic states of TM and phosphorous atoms: (i) bonding states are completely empty or filled for Sc- and Co-doped black and blue phosphorenes, leading to nonmagnetic; (ii) non-bonding d states are partially occupied for Ti-, V-, Cr-, Mn-, Fe- and Ni-doped black and blue phosphorenes, giving rise to large and localized spin moments. These results provide a new route for the potential applications of dilute magnetic semiconductor and half-metal in spintronic devices by employing black and blue phosphorenes. PACS numbers: 73.22.-f, 75.50.Pp, 75.75. + a

  12. Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE analysis of metal-poor stars

    NASA Astrophysics Data System (ADS)

    Amarsi, A. M.; Lind, K.; Asplund, M.; Barklem, P. S.; Collet, R.

    2016-08-01

    As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform detailed 3D non-LTE radiative transfer calculations based on 3D hydrodynamic STAGGER model atmospheres, and employ a new model atom that includes new quantum-mechanical neutral hydrogen collisional rate coefficients. With the exception of the red giant HD122563, we find that the 3D non-LTE models achieve Fe I/Fe II excitation and ionization balance as well as not having any trends with equivalent width to within modelling uncertainties of 0.05 dex, all without having to invoke any microturbulent broadening; for HD122563 we predict that the current best parallax-based surface gravity is overestimated by 0.5 dex. Using a 3D non-LTE analysis, we infer iron abundances from the 3D model atmospheres that are roughly 0.1 dex higher than corresponding abundances from 1D MARCS model atmospheres; these differences go in the same direction as the non-LTE effects themselves.We make available grids of departure coefficients, equivalent widths and abundance corrections, calculated on 1D MARCS model atmospheres and horizontally- and temporally-averaged 3D STAGGER model atmospheres.

  13. Uranyl Ion Complexes with Long-Chain Aliphatic α,ω-Dicarboxylates and 3d-Block Metal Counterions.

    PubMed

    Thuéry, Pierre; Harrowfield, Jack

    2016-03-01

    Twelve new complexes were obtained from reaction of uranyl ions with the aliphatic dicarboxylic acids HOOC-(CH2)n-2-COOH (H2Cn; n = 7-10 and 12) under solvo-hydrothermal conditions, in the presence of 3d-block metal ions (Mn(2+), Fe(3+), Co(2+), Ni(2+), and Cu(2+)) and 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen). In contrast to previously reported triple-stranded helicates obtained with C9(2-) and C12(2-), all these complexes crystallize as polymeric one-dimensional (1D) or two-dimensional (2D) species. [Fe(bipy)3][(UO2)2(C7)3]·3H2O (1), [Cu(phen)2]2[(UO2)3(C7)4(H2O)2]·2H2O (2), and [Cu(bipy)2]2[(UO2)2(C9)3] (6), in which the 3d cation was reduced in situ, are 1D ladderlike polymers displaying tetra- or hexanuclear rings, of sufficient width to encompass two counterions in 2 and 6. The three complexes [Co(phen)3][(UO2)3(C8)3(O)]·H2O (3), [Ni(phen)3][(UO2)3(C8)3(O)]·H2O (4) and [Co(phen)3][(UO2)3(C9)3(O)]·H2O (5) contain bis(μ3-oxo)-bridged tetranuclear secondary building units, and they crystallize as deeply furrowed 2D assemblies. Depending on the nature of the counterion, C10(2-) gives [Ni(bipy)3][(UO2)2(C10)3]·2H2O (7), a 2D network displaying elongated decanuclear rings containing the counterions, or [Mn(phen)3][(UO2)2(C10)3]·6H2O (8), [Co(phen)3][(UO2)2(C10)3]·7H2O (9), and [Ni(phen)3][(UO2)2(C10)3]·7H2O (10), which consist of 2D assemblies with honeycomb topology; the hexanuclear rings in 8-10 are chairlike and occupied by one counterion and two uranyl groups from neighboring layers. Two complexes of the ligand with the longest chain, C12(2-), are reported. [UO2(C12)(bipy)] (11) is a neutral 1D species in which bipy chelates the uranyl ion and plays an important role in the packing through π-stacking interactions. Two polymeric units, 1D and 2D, coexist in the complex [Ni(bipy)3][(UO2)2(C12)3][UO2(C12)(H2O)2]·H2O (12); the 2D network has the honeycomb topology, but the hexanuclear rings are markedly convoluted, with local features akin to

  14. Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

    PubMed Central

    Chen, Hongjun

    2014-01-01

    Summary To better utilize the sunlight for efficient solar energy conversion, the research on visible-light active photocatalysts has recently attracted a lot of interest. The photosensitization of transition metal oxides is a promising approach for achieving effective visible-light photocatalysis. This review article primarily discusses the recent progress in the realm of a variety of nanostructured photosensitizers such as quantum dots, plasmonic metal nanostructures, and carbon nanostructures for coupling with wide-bandgap transition metal oxides to design better visible-light active photocatalysts. The underlying mechanisms of the composite photocatalysts, e.g., the light-induced charge separation and the subsequent visible-light photocatalytic reaction processes in environmental remediation and solar fuel generation fields, are also introduced. A brief outlook on the nanostructure photosensitization is also given. PMID:24991507

  15. Metallic Nanostructures Based on Self-Assembling DNA Templates for Studying Optical Phenomena

    NASA Astrophysics Data System (ADS)

    Pilo-Pais, Mauricio

    DNA origami is a novel self-assembly technique that can be used to form various 2D and 3D objects, and to position matter with nanometer accuracy. It has been used to coordinate the placement of nanoscale objects, both organic and inorganic, to make molecular motor and walkers; and to create optically active nanostructures. In this dissertation, DNA origami templates are used to assemble plasmonic structures. Specifically, engineered Surface Enhanced Raman Scattering (SERS) substrates were fabricated. Gold nanoparticles were selectively placed on the corners of rectangular origami and subsequently enlarged via solution-based metal deposition. The resulting assemblies exhibited "hot spots" of enhanced electromagnetic field between the nanoparticles. These hot spots significantly enhanced the Raman signal from Raman molecules covalently attached to the assemblies. Control samples with only one nanoparticle per DNA template, which therefore lacked inter-particle hot spots, did not exhibit strong enhancement. Furthermore, Raman molecules were used to map out the hot spots' distribution, as the molecules are photo-damaged when experiencing a threshold electric field. This method opens up the prospect of using DNA origami to rationally engineer and assemble plasmonic structures for molecular spectroscopy.

  16. 3D architecture constructed via the confined growth of MoS2 nanosheets in nanoporous carbon derived from metal-organic frameworks for efficient hydrogen production

    NASA Astrophysics Data System (ADS)

    Liu, Yun; Zhou, Xiaoli; Ding, Tao; Wang, Chunde; Yang, Qing

    2015-10-01

    The design and synthesis of robust, high-performance and low-cost three-dimensional (3D) hierarchical structured materials for the electrochemical reduction of water to generate hydrogen is of great significance for practical water splitting applications. In this study, we develop an in situ space-confined method to synthesize an MoS2-based 3D hierarchical structure, in which the MoS2 nanosheets grow in the confined nanopores of metal-organic frameworks (MOFs)-derived 3D carbons as electrocatalysts for efficient hydrogen production. Benefiting from its unique structure, which has more exposed active sites and enhanced conductivity, the as-prepared MoS2/3D nanoporous carbon (3D-NPC) composite exhibits remarkable electrocatalytic activity for the hydrogen evolution reaction (HER) with a small onset overpotential of ~0.16 V, large cathodic currents, small Tafel slope of 51 mV per decade and good durability. We anticipate that this in situ confined growth provides new insights into the construction of high performance catalysts for energy storage and conversion.The design and synthesis of robust, high-performance and low-cost three-dimensional (3D) hierarchical structured materials for the electrochemical reduction of water to generate hydrogen is of great significance for practical water splitting applications. In this study, we develop an in situ space-confined method to synthesize an MoS2-based 3D hierarchical structure, in which the MoS2 nanosheets grow in the confined nanopores of metal-organic frameworks (MOFs)-derived 3D carbons as electrocatalysts for efficient hydrogen production. Benefiting from its unique structure, which has more exposed active sites and enhanced conductivity, the as-prepared MoS2/3D nanoporous carbon (3D-NPC) composite exhibits remarkable electrocatalytic activity for the hydrogen evolution reaction (HER) with a small onset overpotential of ~0.16 V, large cathodic currents, small Tafel slope of 51 mV per decade and good durability. We

  17. Basis set limit electronic excitation energies, ionization potentials, and electron affinities for the 3d transition metal atoms: Coupled cluster and multireference methods

    NASA Astrophysics Data System (ADS)

    Balabanov, Nikolai B.; Peterson, Kirk A.

    2006-08-01

    Recently developed correlation consistent basis sets for the first row transition metal elements Sc-Zn have been utilized to determine complete basis set (CBS) scalar relativistic electron affinities, ionization potentials, and 4s23dn -2-4s1dn -1 electronic excitation energies with single reference coupled cluster methods [CCSD(T), CCSDT, and CCSDTQ] and multireference configuration interaction with three reference spaces: 3d4s, 3d4s4p, and 3d4s4p3d'. The theoretical values calculated with the highest order coupled cluster techniques at the CBS limit, including extrapolations to full configuration interaction, are well within 1kcal/mol of the corresponding experimental data. For the early transition metal elements (Sc-Mn) the internally contracted multireference averaged coupled pair functional method yielded excellent agreement with experiment; however, the atomic properties for the late transition metals (Mn-Zn) proved to be much more difficult to describe with this level of theory, even with the largest reference function of the present work.

  18. Adsorption of alkali, alkaline-earth, simple and 3d transition metal, and nonmetal atoms on monolayer MoS{sub 2}

    SciTech Connect

    Li, X. D.; Fang, Y. M.; Wu, S. Q. E-mail: wsq@xmu.edu.cn; Zhu, Z. Z. E-mail: wsq@xmu.edu.cn

    2015-05-15

    Single adsorption of different atoms on pristine two-dimensional monolayer MoS{sub 2} have been systematically investigated by using density functional calculations with van der Waals correction. The adatoms cover alkali metals, alkaline earth metals, main group metal, 3d-transition metals, coinage metal and nonmetal atoms. Depending on the adatom type, metallic, semimetallic or semiconducting behavior can be found in direct bandgap monolayer MoS{sub 2}. Additionally, local or long-range magnetic moments of two-dimensional MoS{sub 2} sheet can also attained through the adsorption. The detailed atomic-scale knowledge of single adsorption on MoS{sub 2} monolayer is important not only for the sake of a theoretical understanding, but also device level deposition technological application.

  19. Localized surface plasmon resonance induced structure-property relationships of metal nanostructures

    NASA Astrophysics Data System (ADS)

    Vilayurganapathy, Subramanian

    The confluence of nanotechnology and plasmonics has led to new and interesting phenomena. The industrial need for fast, efficient and miniature devices which constantly push the boundaries on device performance tap into the happy marriage between these diverse fields. Designing devices for real life application that give superior performance when compared with existing ones are enabled by a better understanding of their structure-property relationships. Among all the design constraints, without doubt, the shape and size of the nanostructure along with the dielectric medium surrounding it has the maximum influence on the response and thereby the performance of the device. Hence a careful study of the above mentioned parameters is of utmost importance in designing efficient devices. In this dissertation, we synthesize and study the optical properties of nanostructures of different shapes and size. In particular, we estimated the plasmonic near field enhancement via surface-enhanced Raman scattering (SERS) and 2-photon Photoemission electron microscopy (2P-PEEM). We synthesized the nanostructures using four different techniques. One synthesis technique, the thermal growth method was employed to grow interesting Ag and Au nanostructures on Si. The absence of toxic chemicals during nanostructure synthesis via the thermal growth technique opens up myriad possibilities for applications in the fields of biomedical science, bioengineering, drug delivery among others along with the huge advantage of being environment friendly. The other three synthesis techniques (ion implantation, Electrodeposition and FIB lithography) were chosen with the specific goal of designing novel plasmonic metal, metal hybrid nanostructures as photocathode materials in next generation light sources. The synthesis techniques for these novel nanostructures were dictated by the requirement of high quantum efficiency, robustness under constant irradiation and coherent unidirectional electron emission

  20. Functional Metal Oxide Nanostructures: Their Synthesis, Characterization, and Energy Applications

    NASA Astrophysics Data System (ADS)

    Iyer, Aparna

    in oxidation reactions and adsorption of heavy metal. Spontaneous formation of OMS-2 nanospheres was possible by tuning reaction parameters in the ultrasonic atomization process. In the second part, a microwave-hydrothermal route has been developed for the synthesis of 1D cobalt compounds (Chapter 5). These compounds are transformed to spinel type Co3O4 nanorods. The effects of solvents, cobalt sources, and microwave radiation time in the formation of 1D cobalt oxide nanostructures were studied in detail. These materials are catalytically active for CO oxidation and styrene oxidation reactions. Magnesia-yttria nanocomposites with controlled nanoscale grain sizes and homogenous microstructures are useful as IR transparent materials. A simple cost-effective sucrose based sol-gel route was devised for making MgO-Y 2O3 nanocomposites. Grain growth in these nanocomposites was systematically evaluated using transmission electron microscopy studies.

  1. Suppression of infrared absorption in nanostructured metals by controlling Faraday inductance and electron path length.

    PubMed

    Han, Sang Eon

    2016-02-01

    Nanostructured metals have been intensively studied for optical applications over the past few decades. However, the intrinsic loss of metals has limited the optical performance of the metal nanostructures in diverse applications. In particular, light concentration in metals by surface plasmons or other resonances causes substantial absorption in metals. Here, we avoid plasmonic excitations for low loss and investigate methods to further suppress loss in nanostructured metals. We demonstrate that parasitic absorption in metal nanostructures can be significantly reduced over a broad band by increasing the Faraday inductance and the electron path length. For an example structure, the loss is reduced in comparison to flat films by more than an order of magnitude over most of the very broad spectrum between short and long wavelength infrared. For a photodetector structure, the fraction of absorption in the photoactive material increases by two orders of magnitude and the photoresponsivity increases by 15 times because of the selective suppression of metal absorption. These findings could benefit many metal-based applications that require low loss such as photovoltaics, photoconductive detectors, solar selective surfaces, infrared-transparent defrosting windows, and other metamaterials. PMID:26906830

  2. Effect of annealing treatment on K{beta}-to-K{alpha} x-ray intensity ratios of 3d transition-metal alloys

    SciTech Connect

    Han, I.; Demir, L.

    2010-06-15

    The influence of heat annealing treatment on the K{beta}-to-K{alpha} x-ray intensity ratios of 3d transition metal was carried out by x-ray fluorescence studies of various alloy compositions. K{beta}-to-K{alpha} x-ray intensity ratios of Fe, Ni, Ti, Co, and Cu in Fe{sub x}Ni{sub 1-x}, Ti{sub x}Ni{sub 1-x}, and Co{sub x}Cu{sub 1-x} alloys unannealed and thermally annealed at different temperatures have been measured following excitation by 22.69-keV x rays from a 10-mCi {sup 109}Cd radioactive point source. The experimental data obtained after annealing treatment indicate deviations of K{beta}-to-K{alpha} x-ray intensity ratios for 3d transition metals in different alloy compositions from the corresponding ratios for unannealed samples. The present investigation makes it possible to perform reliable interpretation of experimental K{beta}-to-K{alpha} x-ray intensity ratios for various 3d transition metals in their alloys and can also provide quantitative information about the changes of the K{beta}-to-K{alpha} x-ray intensity ratios of these metals with annealing treatment in considered systems.

  3. Comparison of the 2D and 3D Nanostructured Lectin-Based Biosensors for In Situ Detection of Sialic Acid on Glycoproteins

    PubMed Central

    Bertok, Tomas; Sediva, Alena; Vikartovska, Alica; Tkac, Jan

    2016-01-01

    We present here comparison of a build-up of two ultrasensitive lectin biosensors based on 2D or 3D architecture. A 2D lectin biosensor was prepared by a covalent immobilisation of lectin Sambucus nigra agglutinin (SNA) recognising sialic acid directly on a mixed self-assembled monolayer (SAM) on planar gold surfaces. A 3D biosensor was prepared by covalent immobilisation of SNA lectin on a mixed SAM layer formed on gold nanoparticles. Surface plasmon resonance technique allowed to follow kinetics of a mixed SAM (1:1 mixture of 11-mercaptoundecanoic acid and 6-mercaptohexanol) formation on a bare gold electrode and on an electrode modified by 5 nm and 20 nm gold nanoparticles (AuNPs). Results from the study revealed that a mixed SAM formation is slower on surfaces with increased curvature, the process of SAM formation on all surfaces is completed within 6 min, but a density of thiols on such surfaces differs significantly. Quartz crystal microbalance experiments showed that a surface density of immobilised lectin of (2.53 ± 0.01) pmol cm-2 was higher on planar gold surface compared to the surface modified by 20 nm AuNPs with a surface density of (0.94 ± 0.01) pmol cm-2. Even though a larger amount of SNA lectin was immobilised on a surface of the 2D biosensor compared to the 3D biosensor, lectin molecules immobilised on AuNPs were more accessible for its analytes – glycoproteins fetuin and asialofetuin, containing different amount of sialic acid on the protein surface. Most likely a better accessibility of lectin for its analytes on a 3D surface and proper interfacial properties of a 3D surface are behind unprecedented detection limit down to aM level for the lectin biosensor based on such a nanoscale tuned interface.

  4. Enhanced optical transmission and Fano resonance through a nanostructured metal thin film

    PubMed Central

    Xiao, Bo; Pradhan, Sangram K.; Santiago, Kevin C.; Rutherford, Gugu N.; Pradhan, Aswini K.

    2015-01-01

    Artificial and engineered nanostructures expand the degrees of freedom with which one can manipulate the intricate interplay of light and matter. Certain nanostructural arrangements in the excited state enable the efficient electromagnetic coupling of propagating light with localized fields. Here, we demonstrate that light transmitted through a nanostructured metal thin film without any apertures can be significantly enhanced. Distinct asymmetric Fano resonances are observed in the zero-order transmission spectra using an incoherent light source. The transmission efficiency surpasses that of a metal thin film with the same area and thickness at the resonance maxima. The transmission minima and the sharp resonance maxima bear a strong resemblance to the extraordinary optical transmission observed in sub-wavelength nanohole array structures The resonance wavelength closely matches the nanostructural periodicity. The sensitivity of the resonances to the surrounding medium and the transmission efficiency demonstrate the potential for use in energy harvesting, imaging, optical processing and sensing applications. PMID:25981974

  5. Enhanced optical transmission and Fano resonance through a nanostructured metal thin film

    NASA Astrophysics Data System (ADS)

    Xiao, Bo; Pradhan, Sangram K.; Santiago, Kevin C.; Rutherford, Gugu N.; Pradhan, Aswini K.

    2015-05-01

    Artificial and engineered nanostructures expand the degrees of freedom with which one can manipulate the intricate interplay of light and matter. Certain nanostructural arrangements in the excited state enable the efficient electromagnetic coupling of propagating light with localized fields. Here, we demonstrate that light transmitted through a nanostructured metal thin film without any apertures can be significantly enhanced. Distinct asymmetric Fano resonances are observed in the zero-order transmission spectra using an incoherent light source. The transmission efficiency surpasses that of a metal thin film with the same area and thickness at the resonance maxima. The transmission minima and the sharp resonance maxima bear a strong resemblance to the extraordinary optical transmission observed in sub-wavelength nanohole array structures The resonance wavelength closely matches the nanostructural periodicity. The sensitivity of the resonances to the surrounding medium and the transmission efficiency demonstrate the potential for use in energy harvesting, imaging, optical processing and sensing applications.

  6. Uniform metal nanostructures with long-range order via three-step hierarchical self-assembly

    PubMed Central

    Erb, Denise J.; Schlage, Kai; Röhlsberger, Ralf

    2015-01-01

    Large-scale nanopatterning is a major issue in nanoscience and nanotechnology, but conventional top-down approaches are challenging because of instrumentation and process complexity while often lacking the desired spatial resolution. We present a hierarchical bottom-up nanopatterning routine using exclusively self-assembly processes: By combining crystal surface reconstruction, microphase separation of copolymers, and selective metal diffusion, we produce monodisperse metal nanostructures in highly regular arrays covering areas of square centimeters. In situ grazing incidence small-angle x-ray scattering during Fe nanostructure formation evidences an outstanding structural order in the self-assembling system and hints at the possibility of sculpting nanostructures using external process parameters. Thus, we demonstrate that bottom-up nanopatterning is a competitive alternative to top-down routines, achieving comparable pattern regularity, feature size, and patterned areas with considerably reduced effort. Intriguing assets of the proposed fabrication approach include the option for in situ investigations during pattern formation, the possibility of customizing the nanostructure morphology, the capacity to pattern arbitrarily large areas with ultrahigh structure densities unachievable by top-down approaches, and the potential to address the nanostructures individually. Numerous applications of self-assembled nanostructure patterns can be envisioned, for example, in high-density magnetic data storage, in functional nanostructured materials for photonics or catalysis, or in surface plasmon resonance–based sensing. PMID:26601139

  7. Simulation of the emission properties of patterned metal-based nanostructures

    NASA Astrophysics Data System (ADS)

    Li, Weijun; Luo, Jun; Peng, Sha; Zhu, Yaping; Lei, Yu; Tong, Qing; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2015-12-01

    Enormous pressures have been puts on current optical storage technologies as the rapid development of information technologies. Recently, it has been found that the surface plasmon-polaritons'modes (SPPMs) in metallic nanostructures may lead to the high localization of guided light beams with nanometer size and only limited by several factors such as atomic structure, dissipation, and light dispersion, and thus far beyond the common diffraction limit of electromagnetic waves in dielectric media. This discovery provides a way to produce nanoscale light signal and thus makes a significant breakthrough in optical storage technologies. In this paper, our work focuses on the modeling and simulation of particular kinds of patterned metal-based nanostructure fabricated over silicon dioxide (SiO2) wafer. The nanostructures designed are expected to concentrate, deliver incident light energy into nanoscale regions and generate nanoscale light signal. In our research, the duty cycle of patterned nanostructures is taken as a key parameter, and then the factors including the patterned nanostructures, the frequency of the incident electromagnetic wave, the size of patterned nanostructure and the distance arrangement between adjacent single patterns, are taken as variables. The common CST microwave studio is used to simulate beam transportation and transformation behaviors. By comparing electric-field intensity distribution in nano-areas and the reflectance of the nanostructure array, the nano-light-emission effects are analyzed.

  8. Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System

    NASA Astrophysics Data System (ADS)

    Lavrynenko, O. M.; Pavlenko, O. Yu; Shchukin, Yu S.

    2016-02-01

    The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations.

  9. Characteristic of the Nanoparticles Formed on the Carbon Steel Surface Contacting with 3d-Metal Water Salt Solutions in the Open-Air System.

    PubMed

    Lavrynenko, O M; Pavlenko, O Yu; Shchukin, Yu S

    2016-12-01

    The contact of a steel electrode with water dispersion medium in an open-air system leads to the development of various polymorphic iron oxides and oxyhydroxides on the steel surface. Whereas the usage of distilled water causes the obtaining of Fe(II)-Fe(III) layered double hydroxides (green rust) as a primary mineral phase, but in the presence of inorganic 3d-metal water salt solutions, mixed layered double hydroxides (LDHs) together with non-stoichiometric spinel ferrite nanoparticles are formed on the steel surface. Mixed LDHs keep stability against further oxidation and complicate the obtaining of spinel ferrite nanoparticles. Thermal treatment of mixed LDHs among other mineral phases formed via the rotation-corrosion dispergation process at certain temperatures permits to obtain homogenous nanoparticles of spinel ferrites as well as maghemite or hematite doped by 3d-metal cations. PMID:26847693

  10. Structural, electronic and magnetic properties of 3d transition metals embedded graphene-like carbon nitride sheet: A DFT + U study

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Chi, Runze; Li, Chong; Jia, Yu

    2016-03-01

    Using first-principles calculations, we have investigated the structural, electronic and magnetic properties of 3d transition-metals (TMs) embedded two dimensional graphene-like carbon nitride sheet (TMs@g-CN). Our results show that TMs embed in the cavity of g-CN sheet regularly and keep intact of the planar structure, though there is Jahn-Teller distortion inevitably. Additionally, the nonmagnetic and semiconducting sheet can be significantly modulated to be magnetic and metallic behaviors induced by the resonant impurity states between TMs 3d and g-CN 2p orbitals. Moreover, we also explore the magnetic coupling of TMs@g-CN and find that it varies dramatically with the change of the distance between TMs, i.e., from ferromagnetic (FM) to antiferromagnetic (AFM) transition. Finally, the underlying physical mechanism of the above findings is discussed.

  11. Nanoengineering a library of metallic nanostructures using a single microfluidic reactor.

    PubMed

    Sebastián, Víctor; Jensen, Klavs F

    2016-08-18

    Microfluidic synthesis in a microfabricated reactor enables fast and facile synthesis of a wide library of metallic nanostructures: monometallic, bimetallic, anisotropic growth and heterostructures. Specific nanostructures are realized by selection of flow pattern and synthesis parameters. The technique is shown to have advantages over conventional batch technologies. Not only does it allow faster scalable synthesis, but also realization of nanostructures hitherto not reported such as Pt-Ru, Pt-Ni and Pt-Co nanodendrites, Pt-Pd heterostructures, Ag-Pd core-shell NPs, Au-Pd nanodumbbells and Au-Pd nanosheets. PMID:27500728

  12. Room-Temperature Chemical Welding and Sintering of Metallic Nanostructures by Capillary Condensation.

    PubMed

    Yoon, Sung-Soo; Khang, Dahl-Young

    2016-06-01

    Room-temperature welding and sintering of metal nanostructures, nanoparticles and nanowires, by capillary condensation of chemical vapors have successfully been demonstrated. Nanoscale gaps or capillaries that are abundant in layers of metal nanostructures have been found to be the preferred sites for the condensation of chemically oxidizing vapor, H2O2 in this work. The partial dissolution and resolidification at such nanogaps completes the welding/sintering of metal nanostructures within ∼10 min at room-temperature, while other parts of nanostructures remain almost intact due to negligible amount of condensation on there. The welded networks of Ag nanowires have shown much improved performances, such as high electrical conductivity, mechanical flexibility, optical transparency, and chemical stability. Chemically sintered layers of metal nanoparticles, such as Ag, Cu, Fe, Ni, and Co, have also shown orders of magnitude increase in electrical conductivity and improved environmental stability, compared to nontreated ones. Pertinent mechanisms involved in the chemical welding/sintering process have been discussed. Room-temperature welding and sintering of metal nanostructures demonstrated here may find widespread application in diverse fields, such as displays, deformable electronics, wearable heaters, and so forth. PMID:27159354

  13. Three-dimensional (3-D) metal-organic frameworks with 3-pyridin-4-yl-benzoate defining new (3,6)-connected net topologies

    SciTech Connect

    Jiang Xiujuan; Du Miao; Sun Yan; Guo, Jian-Hua; Li, Jin-Shan

    2009-11-15

    Reactions of different metal salts with 3-pyridin-4-yl-benzoic acid (3,4-Hpybz) under ambient condition afford a series of 3-D metal-organic frameworks with two new types of (3,6)-connected net topologies. In the isomorphic complexes [M{sub 2}(mu-H{sub 2}O)(3,4-pybz){sub 4}]{sub n} (M{sup II}=Mn{sup II} for 1, Zn{sup II} for 2, or Cd{sup II} for 3), the octahedral metal nodes are extended by the 3-connected pybz tectons to constitute 3-D arrays with the Schlaefli symbol of (3.4.5)(3{sup 2}.4{sup 4}.5{sup 5}.6{sup 2}.7{sup 2}), whereas [Pb(3,4-pybz){sub 2}]{sub n} (4) shows a completely different 3-D (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 2}.8{sup 9}) framework, which represents a subnet of the (4,8)-connected fluorite lattice. - Graphical abstract: This work presents a series of 3-D metal-organic frameworks with 3-pyridin-4-yl-benzoate, which display new (3,6)-connected net topologies of (3.4.5)(3{sup 2}.4{sup 4}.5{sup 5}.6{sup 2}.7{sup 2}) for Mn{sup II}/Zn{sup II}/Cd{sup II} and (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 2}.8{sup 9}) for Pb{sup II} species.

  14. Design and characterization of metal and semiconducting nanostructures and nanodevices

    NASA Astrophysics Data System (ADS)

    Theiss, Jesse Robert

    intensities. Chapter 3 investigates these nm-separated nanoparticle pairs further. The previous Raman study uses a very narrow wavelength probe to characterize metallic nanostructures with a much broader spectral response. This study builds on the previous work by characterizing the spectral scattering from these "nanogap" structures in the visible and near-IR part of the spectrum, where we built a specialized near-normal incidence dark-field microscopy system to measure particle scattering on TEM-compatible membranes. We find that nanoparticles with these nm-separations tend to exhibit significant dips in their far-field scattering spectra. We further investigate this phenomenon by numerical simulation and find that these dips are a Fano interference that results from strong coupling to higher-order plasmon resonances. This Fano interference is unique compared to other reports in the last four years, where opposing charge distributions at the top and bottom of the nanogap destructively interfere in far-field scattering. We show that the enhanced interparticle coupling is not only due to the small separation between the particles but also due to an enhanced interaction with image charges induced in the underlying substrate. In Chapter 4, we study the length dependence of vibronic and thermal transport properties in carbon nanotubes. The atomic force microscope, a common characterization tool in nanotechnology, is adapted to locally cut through a nanotube's carbon-carbon bonds. The first study looks for changes in phonon energy and Raman scattering intensity as an individual nanotube is divided into smaller pieces. The second study uses Raman scattering from a suspended carbon nanotube to measure the temperature as a laser probe provides localized heating. The temperature in the suspended section of the carbon nanotube drastically increases as we create a bottleneck for heat flow at the nanotube-substrate contact. Chapter 5 details the fabrication process and experimental

  15. Reaction Current Phenomenon in Bifunctional Catalytic Metal-Semiconductor Nanostructures

    NASA Astrophysics Data System (ADS)

    Hashemian, Mohammad Amin

    Energy transfer processes accompany every elementary step of catalytic chemical processes on material surface including molecular adsorption and dissociation on atoms, interactions between intermediates, and desorption of reaction products from the catalyst surface. Therefore, detailed understanding of these processes on the molecular level is of great fundamental and practical interest in energy-related applications of nanomaterials. Two main mechanisms of energy transfer from adsorbed particles to a surface are known: (i) adiabatic via excitation of quantized lattice vibrations (phonons) and (ii) non-adiabatic via electronic excitations (electron/hole pairs). Electronic excitations play a key role in nanocatalysis, and it was recently shown that they can be efficiently detected and studied using Schottky-type catalytic nanostructures in the form of measureable electrical currents (chemicurrents) in an external electrical circuit. These nanostructures typically contain an electrically continuous nanocathode layers made of a catalytic metal deposited on a semiconductor substrate. The goal of this research is to study the direct observations of hot electron currents (chemicurrents) in catalytic Schottky structures, using a continuous mesh-like Pt nanofilm grown onto a mesoporous TiO2 substrate. Such devices showed qualitatively different and more diverse signal properties, compared to the earlier devices using smooth substrates, which could only be explained on the basis of bifunctionality. In particular, it was necessary to suggest that different stages of the reaction are occurring on both phases of the catalytic structure. Analysis of the signal behavior also led to discovery of a formerly unknown (very slow) mode of the oxyhydrogen reaction on the Pt/TiO2(por) system occurring at room temperature. This slow mode was producing surprisingly large stationary chemicurrents in the range 10--50 microA/cm2. Results of the chemicurrent measurements for the bifunctional

  16. Formation of nanostructured Group IIA metal activated sensors: The transformation of Group IIA metal compound sites

    NASA Astrophysics Data System (ADS)

    Tune, Travis C.; Baker, Caitlin; Hardy, Neil; Lin, Arthur; Widing, Timothy J.; Gole, James L.

    2015-05-01

    Trends in the Group IIA metal oxides and hydroxides of magnesium, calcium, and barium are unique in the periodic table. In this study we find that they display novel trends as decorating nanostructures for extrinsic semiconductor interfaces. The Group IIA metal ions are strong Lewis acids. We form these M2+ ions in aqueous solution and bring these solutions in contact with a porous silicon interface to form interfaces for conductometric measurements. Observed responses are consistent with the formation of MgO whereas the heavier elements display behaviors which suggest the effect of their more basic nature. Mg(OH)2, when formed, represents a weak base whereas the heavier metal hydroxides of Ca, Sr, and Ba are strong bases. However, the hydroxides tend to give up hydrogen and act as Brönsted acids. For the latter elements, the reversible interaction response of nanostructures deposited to the porous silicon (PS) interface is modified, as the formation of more basic sites appears to compete with M2+ Lewis acidity and hydroxide Brönsted acidity. Mg2+ forms an interface whose response to the analytes NH3 and NO is consistent with MgO and well explained by the recently developing Inverse Hard/Soft Acid/Base model. The behavior of the Ca2+ and Ba2+ decorated interfaces as they interact with the hard base NH3 follows a reversal of the model, indicating a decrease in acidic character as the observed conductometric response suggests the interaction with hydroxyl groups. A change from oxide-like to hydroxide-like constituents is supported by XPS studies. The changes in conductometric response is easily monitored in contrast to changes associated with the Group IIA oxides and hydroxides observed in XPS, EDAX, IR, and NMR measurements.

  17. Plasmonic mode interferences and Fano resonances in Metal-Insulator- Metal nanostructured interface

    PubMed Central

    Nicolas, Rana; Lévêque, Gaëtan; Marae-Djouda, Joseph; Montay, Guillame; Madi, Yazid; Plain, Jérôme; Herro, Ziad; Kazan, Michel; Adam, Pierre-Michel; Maurer, Thomas

    2015-01-01

    Metal-insulator-metal systems exhibit a rich underlying physics leading to a high degree of tunability of their spectral properties. We performed a systematic study on a metal-insulator-nanostructured metal system with a thin 6 nm dielectric spacer and showed how the nanoparticle sizes and excitation conditions lead to the tunability and coupling/decoupling of localized and delocalized plasmonic modes. We also experimentally evidenced a tunable Fano resonance in a broad spectral window 600 to 800 nm resulting from the interference of gap modes with white light broad band transmitted waves at the interface playing the role of the continuum. By varying the incident illumination angle shifts in the resonances give the possibility to couple or decouple the localized and delocalized modes and to induce a strong change of the asymmetric Fano profile. All these results were confirmed with a crossed comparison between experimental and theoretical measurements, confirming the nature of different modes. The high degree of control and tunability of this plasmonically rich system paves the way for designing and engineering of similar systems with numerous applications. In particular, sensing measurements were performed and a figure of merit of 3.8 was recorded ranking this sensor among the highest sensitive in this wavelength range. PMID:26399425

  18. Plasmonic mode interferences and Fano resonances in Metal-Insulator-Metal nanostructured interface.

    PubMed

    Nicolas, Rana; Lévêque, Gaëtan; Marae-Djouda, Joseph; Montay, Guillame; Madi, Yazid; Plain, Jérôme; Herro, Ziad; Kazan, Michel; Adam, Pierre-Michel; Maurer, Thomas

    2015-01-01

    Metal-insulator-metal systems exhibit a rich underlying physics leading to a high degree of tunability of their spectral properties. We performed a systematic study on a metal-insulator-nanostructured metal system with a thin 6 nm dielectric spacer and showed how the nanoparticle sizes and excitation conditions lead to the tunability and coupling/decoupling of localized and delocalized plasmonic modes. We also experimentally evidenced a tunable Fano resonance in a broad spectral window 600 to 800 nm resulting from the interference of gap modes with white light broad band transmitted waves at the interface playing the role of the continuum. By varying the incident illumination angle shifts in the resonances give the possibility to couple or decouple the localized and delocalized modes and to induce a strong change of the asymmetric Fano profile. All these results were confirmed with a crossed comparison between experimental and theoretical measurements, confirming the nature of different modes. The high degree of control and tunability of this plasmonically rich system paves the way for designing and engineering of similar systems with numerous applications. In particular, sensing measurements were performed and a figure of merit of 3.8 was recorded ranking this sensor among the highest sensitive in this wavelength range. PMID:26399425

  19. Plasmonic mode interferences and Fano resonances in Metal-Insulator- Metal nanostructured interface

    NASA Astrophysics Data System (ADS)

    Nicolas, Rana; Lévêque, Gaëtan; Marae-Djouda, Joseph; Montay, Guillame; Madi, Yazid; Plain, Jérôme; Herro, Ziad; Kazan, Michel; Adam, Pierre-Michel; Maurer, Thomas

    2015-09-01

    Metal-insulator-metal systems exhibit a rich underlying physics leading to a high degree of tunability of their spectral properties. We performed a systematic study on a metal-insulator-nanostructured metal system with a thin 6 nm dielectric spacer and showed how the nanoparticle sizes and excitation conditions lead to the tunability and coupling/decoupling of localized and delocalized plasmonic modes. We also experimentally evidenced a tunable Fano resonance in a broad spectral window 600 to 800 nm resulting from the interference of gap modes with white light broad band transmitted waves at the interface playing the role of the continuum. By varying the incident illumination angle shifts in the resonances give the possibility to couple or decouple the localized and delocalized modes and to induce a strong change of the asymmetric Fano profile. All these results were confirmed with a crossed comparison between experimental and theoretical measurements, confirming the nature of different modes. The high degree of control and tunability of this plasmonically rich system paves the way for designing and engineering of similar systems with numerous applications. In particular, sensing measurements were performed and a figure of merit of 3.8 was recorded ranking this sensor among the highest sensitive in this wavelength range.

  20. 3D TiO2@Ni(OH)2 Core-shell Arrays with Tunable Nanostructure for Hybrid Supercapacitor Application

    PubMed Central

    Ke, Qingqing; Zheng, Minrui; Liu, Huajun; Guan, Cao; Mao, Lu; Wang, John

    2015-01-01

    Three dimensional hierarchical nanostructures have attracted great attention for electrochemical energy storage applications. In this work, self-supported TiO2@Ni(OH)2 core-shell nanowire arrays are prepared on carbon fiber paper via the combination of hydrothermal synthesis and chemical bath deposition. In this core-shell hybrid, the morphology and wall size of the interconnected nanoflake shell of Ni(OH)2 can be tuned through adjusting the concentration of ammonia solution. Heterogeneous nucleation and subsequent oriented crystal growth are identified to be the synthesis mechanism affecting the nanostructure of the shell material, which consequently determines the electrochemical performance in both energy storage and charge transfer. Superior capabilities of 264 mAhg−1 at 1 A g−1 and 178 mAh g−1 at 10 A g−1 are achieved with the core-shell hybrids of the optimized structure. The asymmetric supercapacitor prototype, comprising of TiO2@Ni(OH)2 as the anode and mesoporous carbons (MCs) as the cathode, is shown to exhibit superior electrochemical performance with high energy and power densities. The present work provides a clear illustration of the structure-property relationship in nanocrystal synthesis and offers a potential strategy to enhance the battery type Ni(OH)2 electrode in a hybrid supercapacitor device. PMID:26353970

  1. 3D TiO2@Ni(OH)2 Core-shell Arrays with Tunable Nanostructure for Hybrid Supercapacitor Application

    NASA Astrophysics Data System (ADS)

    Ke, Qingqing; Zheng, Minrui; Liu, Huajun; Guan, Cao; Mao, Lu; Wang, John

    2015-09-01

    Three dimensional hierarchical nanostructures have attracted great attention for electrochemical energy storage applications. In this work, self-supported TiO2@Ni(OH)2 core-shell nanowire arrays are prepared on carbon fiber paper via the combination of hydrothermal synthesis and chemical bath deposition. In this core-shell hybrid, the morphology and wall size of the interconnected nanoflake shell of Ni(OH)2 can be tuned through adjusting the concentration of ammonia solution. Heterogeneous nucleation and subsequent oriented crystal growth are identified to be the synthesis mechanism affecting the nanostructure of the shell material, which consequently determines the electrochemical performance in both energy storage and charge transfer. Superior capabilities of 264 mAhg-1 at 1 A g-1 and 178 mAh g-1 at 10 A g-1 are achieved with the core-shell hybrids of the optimized structure. The asymmetric supercapacitor prototype, comprising of TiO2@Ni(OH)2 as the anode and mesoporous carbons (MCs) as the cathode, is shown to exhibit superior electrochemical performance with high energy and power densities. The present work provides a clear illustration of the structure-property relationship in nanocrystal synthesis and offers a potential strategy to enhance the battery type Ni(OH)2 electrode in a hybrid supercapacitor device.

  2. 3D TiO2@Ni(OH)2 Core-shell Arrays with Tunable Nanostructure for Hybrid Supercapacitor Application.

    PubMed

    Ke, Qingqing; Zheng, Minrui; Liu, Huajun; Guan, Cao; Mao, Lu; Wang, John

    2015-01-01

    Three dimensional hierarchical nanostructures have attracted great attention for electrochemical energy storage applications. In this work, self-supported TiO2@Ni(OH)2 core-shell nanowire arrays are prepared on carbon fiber paper via the combination of hydrothermal synthesis and chemical bath deposition. In this core-shell hybrid, the morphology and wall size of the interconnected nanoflake shell of Ni(OH)2 can be tuned through adjusting the concentration of ammonia solution. Heterogeneous nucleation and subsequent oriented crystal growth are identified to be the synthesis mechanism affecting the nanostructure of the shell material, which consequently determines the electrochemical performance in both energy storage and charge transfer. Superior capabilities of 264 mAh g(-1) at 1 A g(-1) and 178 mAh g(-1) at 10 A g(-1) are achieved with the core-shell hybrids of the optimized structure. The asymmetric supercapacitor prototype, comprising of TiO2@Ni(OH)2 as the anode and mesoporous carbons (MCs) as the cathode, is shown to exhibit superior electrochemical performance with high energy and power densities. The present work provides a clear illustration of the structure-property relationship in nanocrystal synthesis and offers a potential strategy to enhance the battery type Ni(OH)2 electrode in a hybrid supercapacitor device. PMID:26353970

  3. Black metal thin films by deposition on dielectric antireflective moth-eye nanostructures

    PubMed Central

    Christiansen, Alexander B.; Caringal, Gideon P.; Clausen, Jeppe S.; Grajower, Meir; Taha, Hesham; Levy, Uriel; Asger Mortensen, N.; Kristensen, Anders

    2015-01-01

    Although metals are commonly shiny and highly reflective, we here show that thin metal films appear black when deposited on a dielectric with antireflective moth-eye nanostructures. The nanostructures were tapered and close-packed, with heights in the range 300-600 nm, and a lateral, spatial frequency in the range 5–7 μm−1. A reflectance in the visible spectrum as low as 6%, and an absorbance of 90% was observed for an Al film of 100 nm thickness. Corresponding experiments on a planar film yielded 80% reflectance and 20% absorbance. The observed absorbance enhancement is attributed to a gradient effect causing the metal film to be antireflective, analogous to the mechanism in dielectrics and semiconductors. We find that the investigated nanostructures have too large spatial frequency to facilitate efficient coupling to the otherwise non-radiating surface plasmons. Applications for decoration and displays are discussed. PMID:26035526

  4. Nanostructure of Metallic Particles in Light Water Reactor Used Nuclear Fuel

    SciTech Connect

    Buck, Edgar C.; Mausolf, Edward J.; Mcnamara, Bruce K.; Soderquist, Chuck Z.; Schwantes, Jon M.

    2015-03-11

    The extraordinary nano-structure of metallic particles in light water reactor fuels points to possible high reactivity through increased surface area and a high concentration of high energy defect sites. We have analyzed the metallic epsilon particles from a high burn-up fuel from a boiling water reactor using transmission electron microscopy and have observed a much finer nanostructure in these particles than has been reported previously. The individual round particles that varying in size between ~20 and ~50 nm appear to consist of individual crystallites on the order of 2-3 nm in diameter. It is likely that in-reactor irradiation induce displacement cascades results in the formation of the nano-structure. The composition of these metallic phases is variable yet the structure of the material is consistent with the hexagonal close packed structure of epsilon-ruthenium. These findings suggest that unusual catalytic behavior of these materials might be expected, particularly under accident conditions.

  5. DOE/BES/NSET annual report on growth of metal and semiconductor nanostructures using localized photocatalysts.

    SciTech Connect

    Haddad, Raid Edward; Brinker, C. Jeffrey; Shelnutt, John Allen; Yang, Yi; Nuttall, H. Eric; Watt, Richard K.; Singl, Anup K.; Challa, Sivakumar R.; Wang, Zhongchun; van Swol, Frank B.; Pereira, Eulalia; Qiu, Yan; Jiang, Ying-Bing; Xu, Huifang; Medforth, Craig J.; Song, Yujiang

    2003-10-01

    Our overall goal is to understand and develop a novel light-driven approach to the controlled growth of unique metal and semiconductor nanostructures and nanomaterials. In this photochemical process, bio-inspired porphyrin-based photocatalysts reduce metal salts in aqueous solutions at ambient temperatures to provide metal nucleation and growth centers. Photocatalyst molecules are pre-positioned at the nanoscale to control the location and morphology of the metal nanostructures grown. Self-assembly, chemical confinement, and molecular templating are some of the methods used for nanoscale positioning of the photocatalyst molecules. When exposed to light, the photocatalyst molecule repeatedly reduces metal ions from solution, leading to deposition and the synthesis of the new nanostructures and nanostructured materials. Studies of the photocatalytic growth process and the resulting nanostructures address a number of fundamental biological, chemical, and environmental issues and draw on the combined nanoscience characterization and multi-scale simulation capabilities of the new DOE Center for Integrated Nanotechnologies, the University of New Mexico, and Sandia National Laboratories. Our main goals are to elucidate the processes involved in the photocatalytic growth of metal nanomaterials and provide the scientific basis for controlled synthesis. The nanomaterials resulting from these studies have applications in nanoelectronics, photonics, sensors, catalysis, and micromechanical systems. The proposed nanoscience concentrates on three thematic research areas: (1) the creation of nanoscale structures for realizing novel phenomena and quantum control, (2) understanding nanoscale processes in the environment, and (3) the development and use of multi-scale, multi-phenomena theory and simulation. Our goals for FY03 have been to understand the role of photocatalysis in the synthesis of dendritic platinum nanostructures grown from aqueous surfactant solutions under ambient

  6. Synthesis and characterization of ZnO nanostructures on noble-metal coated substrates

    NASA Astrophysics Data System (ADS)

    Dikovska, A. Og.; Atanasova, G. B.; Avdeev, G. V.; Nedyalkov, N. N.

    2016-06-01

    In this work, ZnO nanostructures were fabricated on noble-metal (Au, Ag and Au-Ag alloys) coated silicon substrates by applying pulsed laser deposition. The samples were prepared at a substrate temperature of 550 °C, an oxygen pressure of 5 Pa, and a laser fluence of 2 J cm-2 - process parameters usually used for deposition of smooth and dense thin films. The metal layer's role is substantial for the preparation of nanostructures. Heating of the substrate changed the morphology of the metal layer and, subsequently, nanoparticles were formed. The use of different metal particles resulted in different morphologies and properties of the ZnO nanostructures synthesized. The morphology of the ZnO nanostructures was related to the Au-Ag alloy's content of the catalyst layer. It was found that the morphology of the ZnO nanostructures evolved from nanorods to nanobelts as the ratio of Au/Ag in the alloy catalyst was varied. The use of a small quantity of Ag in the Au-Ag catalyst (Au3Ag) layer resulted predominantly in the deposition of ZnO nanorods. A higher Ag content in the catalyst alloy (AuAg2) layer resulted in the growth of a dense structure of ZnO nanobelts.

  7. Nanostructuring of metal surfaces by corrosion for efficient water splitting

    NASA Astrophysics Data System (ADS)

    Lee, Jooyoung; Lim, Guh-Hwan; Lim, Byungkwon

    2016-01-01

    We show that simply by corroding Ni foam in an aqueous solution, it is possible to produce nanostructured surfaces. When Ni foam was corroded in water or an aqueous solution containing NaCl, a dense array of Ni(OH)2 nanosheets was produced on the surface of the foam. When corroded in the presence of RuCl3, the nanostructured surface composed of Ni(OH)2 nanosheets decorated with ultrasmall RuO2 nanoparticles was obtained. At an applied voltage of 1.7 V, the combination of these two nanostructured surfaces yielded a water-splitting current density more than three times that obtained on the commercial Pt wire electrodes.

  8. Direct growth of carbon nanofibers to generate a 3D porous platform on a metal contact to enable an oxygen reduction reaction.

    PubMed

    Pan, David; Ombaba, Matthew; Zhou, Zhi-You; Liu, Yang; Chen, Shaowei; Lu, Jennifer

    2012-12-21

    For carbon nanotube-based electronics to achieve their full performance potential, it is imperative to minimize the contact resistance between macroscale metal contacts and the carbon nanotube (CNT) nanoelectrodes. We have developed a three-dimensional electrode platform that consists of carbon nanofibers (CNFs) that are directly grown on a metal contact, such as copper (Cu). Carbon nanofiber morphology can be tailored by adjusting the annealing time of a thin electrochemically deposited nickel catalyst layer on copper. We demonstrate that increasing the annealing time increases the amount of copper infused into the nickel catalyst layer. This reduces the carbon deposition rate, and consequently a more well-defined CNF 3D architecture can be fabricated. This direct growth of CNFs on a Cu substrate yields an excellent electron transfer pathway, with contact resistance between CNFs and Cu being comparable to that of a Cu-Cu interface. Furthermore, the excellent bonding strength between CNFs and Cu can be maintained over prolonged periods of ultrasonication. The porous 3D platform affixed with intertwined CNFs allows facile surface functionalization. Using a simple solution soaking procedure, the CNF surface has been successfully functionalized with iron(II) phthalocyanine (FePc). FePc functionalized CNFs exhibit excellent oxygen reduction capability, equivalent to platinum-carbon electrodes. This result demonstrates the technological promise of this new 3D electrode platform that can be exploited in other applications that include sensing, battery, and supercapacitors. PMID:23171171

  9. Experimental investigation of off-stoichiometry and 3d transition metal (Mn, Ni, Cu)-substitution in single-crystalline FePt thin films

    NASA Astrophysics Data System (ADS)

    Ono, Takuya; Nakata, Hitoshi; Moriya, Tomohiro; Kikuchi, Nobuaki; Okamoto, Satoshi; Kitakami, Osamu; Shimatsu, Takehito

    2016-05-01

    In L10 (fct)-FePt thin films, both tuning Fe and Pt concentrations and substitution with third-metal were studied for magnetic characteristic optimization. We investigated single-crystalline FePt-X (X = Mn, Ni, Cu) thin films grown epitaxially on MgO(001) substrates at a substrate temperature of 350 °C by changing Fe, Pt, and X contents, and explored the effects of off-stoichiometry and 3d-metal-substitution. The magnetic moment per atom (m) of FePt-X films as a function of the effective number of valence electrons (neff) in 3d metal sites follows the Slater-Pauling-type trend, by which m decreases by the neff deviation from neff = 8, independently of the X metal and the Pt concentration. The magnetic anisotropy (Ku) exhibits neff dependence similar to m. This trend was almost independent of the Pt concentration after compensation using the theoretical prediction on the relation between Ku and Fe/Pt concentrations. Such a trend has been proved for stoichiometric FePt-X films, but it was clarified as robust against off-stoichiometry. The compensated Ku ( Ku comp ) of FePt-Mn and FePt-Cu followed a similar trend to that predicted by the rigid-band model, although the Ku comp of the FePt-Mn thin films dropped more rapidly than the rigid band calculation. However, it followed the recent first-principles calculation.

  10. Metal-enhanced intrinsic fluorescence of nucleic acids using platinum nanostructured substrates

    NASA Astrophysics Data System (ADS)

    Akbay, Nuriye; Mahdavi, Farhad; Lakowicz, Joseph R.; Ray, Krishanu

    2012-10-01

    We investigated the feasibility of using platinum nanostructures to accomplish the metal-enhanced fluorescence (MEF) in the UV spectral region. We examine the possibility for detection of the intrinsic fluorescence from nucleotides and G-quadruplex DNA on platinum nanoparticles. Guanosine monophosphate (GMP) showed significant increases (˜20-fold) in fluorescence intensities in the presence of platinum nanostructures when compared to quartz controls. G-quadruplex DNA demonstrated ˜5-fold increase in fluorescence intensity and higher photostability in the presence of Pt nanostructures. We performed Finite Element Method simulations to explore how Pt nanoparticles interact with plane waves and conformed that the Pt nanostructures are promising for enhancing the fluorescence emission in the UV region.

  11. Exciton and electron transport in metal oxide and metal-insulator nanostructures

    NASA Astrophysics Data System (ADS)

    Hess, Wayne; Joly, Alan; Halliday, Matthew; Shluger, Alexander; Sushko, Peter

    2014-03-01

    Understanding the dynamics of electronic excited states in solids is essential to forming mechanistic models relevant to electron and energy transport in materials. Irradiation of materials by ultraviolet (UV) photons, produces energetic species such as holes and free electrons, that relax to form electron-hole pairs and excitons capable of driving surface and bulk reactions such as atomic desorption. Photostimulated desorption experiments, when combined with ab-initio calculations, can be used to develop models for exciton transport and subsequent excited state dynamics. We use pulsed UV lasers to excite specific surface and bulk states of nano-structured metal oxides and measure velocities of desorbed atoms under controlled conditions. By measuring O-atom kinetic energy distributions, as a function of laser frequency, we demonstrate exciton transport on the surface and in the bulk of metal-oxides. We further interrogate electron and exciton dynamics at the metal-insulator interface of thin CsBr films grown on Cu(100). Photoexcitation at 6.4 eV specifically excites the CsBr surface exciton which leads to desorption of neutral Br-atoms with hyperthermal kinetic energies. In dramatic contrast, we observe thermal energy Br atoms from CsBr grown on Cu. The hyperthermal desorption channel is entirely quenched for UV laser desorption of Br atoms even for thick (>60 nm) CsBr films on Cu. Possible models for electron transport and exciton relaxation will be discussed.

  12. Controlled synthesis of heterogeneous metal-titania nanostructures and their applications.

    PubMed

    Liu, Ran; Sen, Ayusman

    2012-10-24

    We describe a new synthetic approach to heterogeneous metal-TiO(2) nanomaterials based on conversion of Ti(3+) to hydrous TiO(2) occurring uniquely on the nanostructured metallic surfaces such as Pt, Au, and Ni nanowires and nanoparticles. The TiO(2) growth mechanism was studied by designing an electrochemical cell. A variety of heterogeneous metal-TiO(2) nanostructures, such as segmented metal-TiO(2) nanowires, core-shell metal-TiO(2) nano/microparticles, and composite metal-TiO(2) nanotubes, can be fabricated by varying the morphology of the seeding metal nanostructure or controlling selective TiO(2) growth on different surfaces of the metallic nanomaterial. Altering the reaction time and Ti(3+) concentration allows the TiO(2) segment lengths or TiO(2) shell thicknesses to be finely tuned. Coaxial Au-TiO(2) nanorod arrays were demonstrated to be fast lithium-ion storage materials, while the core-shell Ni-TiO(2) nanoparticles exhibited excellent photodegradation properties as magnetic recyclable photocatalysts. PMID:22524321

  13. Sub-Nanostructured Non Transition Metal Complex Grids for Hydrogen Storage

    SciTech Connect

    Dr. Orhan Talu; Dr. Surendra N. Tewari

    2007-10-27

    This project involved growing sub-nanostructured metal grids to increase dynamic hydrogen storage capacity of metal hydride systems. The nano particles of any material have unique properties unlike its bulk form. Nano-structuring metal hydride materials can result in: {sm_bullet}Increased hydrogen molecule dissociation rate, {sm_bullet} Increased hydrogen atom transport rate, {sm_bullet} Decreased decrepitation caused by cycling, {sm_bullet} Increased energy transfer in the metal matrix, {sm_bullet} Possible additional contribution by physical adsorption, and {sm_bullet} Possible additional contribution by quantum effects The project succeeded in making nano-structured palladium using electrochemical growth in templates including zeolites, mesoporous silica, polycarbonate films and anodized alumina. Other metals were used to fine-tune the synthesis procedures. Palladium was chosen to demonstrate the effects of nano-structuring since its bulk hydrogen storage capacity and kinetics are well known. Reduced project funding was not sufficient for complete characterization of these materials for hydrogen storage application. The project team intends to seek further funding in the future to complete the characterization of these materials for hydrogen storage.

  14. 3D Hierarchical Bi2S 3 Nanostructures by Polyvinylpyrrolidone (PVP) and Chloride Ion-Assisted Synthesis and Their Photodetecting Properties.

    PubMed

    Ding, Taotao; Dai, Jiangnan; Xu, Juan; Wang, Jin; Tian, Wu; Huo, Kaifu; Fang, Yanyan; Chen, Changqing

    2015-12-01

    A solvothermal method has been employed to synthesize bismuth sulfide (Bi2S3) with three-dimensional (3D) hierarchical architectures. The influences of different types of surfactants and Cl(-) species on the size and morphology were investigated. A possible formation mechanism was also proposed on the basis of time-dependent experiments. The photoresponse properties show that the conductivity of Bi2S3 micro-flowers is significantly enhanced and the photocurrent is approximately two orders of magnitude larger than the dark current. The response and decay times are estimated to be 142 and 151 ms, respectively. It is expected that hierarchical architectures Bi2S3 may provide a new pathway to develop advanced nanomaterial for high-speed and high-sensitivity photoelectrical switches and photodetecting devices. PMID:26156218

  15. 3D Hierarchical Bi2S3 Nanostructures by Polyvinylpyrrolidone (PVP) and Chloride Ion-Assisted Synthesis and Their Photodetecting Properties

    NASA Astrophysics Data System (ADS)

    Ding, Taotao; Dai, Jiangnan; Xu, Juan; Wang, Jin; Tian, Wu; Huo, Kaifu; Fang, Yanyan; Chen, Changqing

    2015-07-01

    A solvothermal method has been employed to synthesize bismuth sulfide (Bi2S3) with three-dimensional (3D) hierarchical architectures. The influences of different types of surfactants and Cl- species on the size and morphology were investigated. A possible formation mechanism was also proposed on the basis of time-dependent experiments. The photoresponse properties show that the conductivity of Bi2S3 micro-flowers is significantly enhanced and the photocurrent is approximately two orders of magnitude larger than the dark current. The response and decay times are estimated to be 142 and 151 ms, respectively. It is expected that hierarchical architectures Bi2S3 may provide a new pathway to develop advanced nanomaterial for high-speed and high-sensitivity photoelectrical switches and photodetecting devices.

  16. Optical fiber tip with point light source of SPPs driven by three-dimensional nanostructured asymmetric metal-insulator-metal layer cap

    NASA Astrophysics Data System (ADS)

    Oshikane, Yasushi; Murai, Kensuke; Nakano, Motohiro

    2015-09-01

    Numerical analysis of three dimensional optical electro-magnetic field in a circular-truncated conical optical fiber covered by asymmetric MIM structure has been performed by a commercial finite element method package, COMSOL Multiphysics coupled with Wave Optics Module. The outermost thick metallic layer has twin nano-hole, and the waveguiding twin-hole could draw surface plasmon polaritions (SPPs) excited in the MIM structure to the surface. Finally the guided two SPPs could unite each other and may create a single bright spot. The systematic simulation is continuing, and the results will give us valuable counsel for control of surface plasmon polaritons (SPPs) appearing around the MIM structure and twin nano-hole. (1) Optimal design of the 3D FEM model for 8-core Xeon server and rational approach for the FEM analysis, (2) behavior of SPPs affected by wavelength and polarization of light travel through fiber, (3) change in excitation condition of SPPs caused by shape of the MIM structure and twin-hole, (4) effectiveness of additional nanostructures that are aimed at focusing control of two SPPs come out from the corners of twin-hole, (5) scanning ability of the MIM/twin-hole probe at nanostructured sample surface (i.e. amount of forward and backward scattering of SPPs) will be presented and discussed. Several FIBed prototypes and their characteristic of light emission will also reported.

  17. The Three-Dimensional Micro- and Nanostructure of the Aortic Medial Lamellar Unit Measured Using 3D Confocal & Electron Microscopy Imaging

    PubMed Central

    O’Connell, Mary K; Murthy, Sushila; Phan, Samson; Xu, Chengpei; Buchanan, JoAnn; Spilker, Ryan; Dalman, Ronald L; Zarins, Christopher K; Denk, Winfried; Taylor, Charles A

    2009-01-01

    Changes in arterial wall composition and function underlie all forms of vascular disease. The fundamental structural and functional unit of the aortic wall is the medial lamellar unit (MLU). While the basic composition and organization of the MLU is known, three-dimensional (3D) microstructural details are tenuous, due (in part) to lack of three-dimensional data at micro- and nano-scales. We applied novel electron and confocal microscopy techniques to obtain 3D volumetric information of aortic medial microstructure at micro- and nano-scales with all constituents present. For the rat abdominal aorta, we show that medial elastin has three primary forms: with approximately 71% of total elastin as thick, continuous lamellar sheets, 27% as thin, protruding interlamellar elastin fibers (IEFs), and 2% as thick radial struts. Elastin pores are not simply holes in lamellar sheets, but are indented and gusseted openings in lamellae. Smooth Muscle Cells (SMCs) weave throughout the interlamellar elastin framework, with cytoplasmic extensions abutting IEFs, resulting in approximately 20° radial tilt (relative to the lumen surface) of elliptical SMC nuclei. Collagen fibers are organized as large, parallel bundles tightly enveloping SMC nuclei. Quantification of the orientation of collagen bundles, SMC nuclei, and IEFs reveal that all three primary medial constituents have predominantly circumferential orientation, correlating with reported circumferentially dominant values of physiological stress, collagen fiber recruitment, and tissue stiffness. This high resolution three-dimensional view of the aortic media reveals MLU microstructure details that suggest a highly complex and integrated mural organization that correlates with aortic mechanical properties. PMID:18248974

  18. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization

    PubMed Central

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-01-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g−1 at 1.2 V in 500 mg l−1 NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications. PMID:27608826

  19. 3D Finite Element Modelling of Cutting Forces in Drilling Fibre Metal Laminates and Experimental Hole Quality Analysis

    NASA Astrophysics Data System (ADS)

    Giasin, Khaled; Ayvar-Soberanis, Sabino; French, Toby; Phadnis, Vaibhav

    2016-07-01

    Machining Glass fibre aluminium reinforced epoxy (GLARE) is cumbersome due to distinctively different mechanical and thermal properties of its constituents, which makes it challenging to achieve damage-free holes with the acceptable surface quality. The proposed work focuses on the study of the machinability of thin (~2.5 mm) GLARE laminate. Drilling trials were conducted to analyse the effect of feed rate and spindle speed on the cutting forces and hole quality. The resulting hole quality metrics (surface roughness, hole size, circularity error, burr formation and delamination) were assessed using surface profilometry and optical scanning techniques. A three dimensional (3D) finite-element (FE) model of drilling GLARE laminate was also developed using ABAQUS/Explicit to help understand the mechanism of drilling GLARE. The homogenised ply-level response of GLARE laminate was considered in the FE model to predict cutting forces in the drilling process.

  20. Electrospun carbon nanofibers reinforced 3D porous carbon polyhedra network derived from metal-organic frameworks for capacitive deionization.

    PubMed

    Liu, Yong; Ma, Jiaqi; Lu, Ting; Pan, Likun

    2016-01-01

    Carbon nanofibers reinforced 3D porous carbon polyhedra network (e-CNF-PCP) was prepared through electrospinning and subsequent thermal treatment. The morphology, structure and electrochemical performance of the e-CNF-PCP were characterized using scanning electron microscopy, Raman spectra, nitrogen adsorption-desorption, cyclic voltammetry and electrochemical impedance spectroscopy, and their electrosorption performance in NaCl solution was studied. The results show that the e-CNF-PCP exhibits a high electrosorption capacity of 16.98 mg g(-1) at 1.2 V in 500 mg l(-1) NaCl solution, which shows great improvement compared with those of electrospun carbon nanofibers and porous carbon polyhedra. The e-CNF-PCP should be a very promising candidate as electrode material for CDI applications. PMID:27608826

  1. Hybrid nickel manganese oxide nanosheet-3D metallic dendrite percolation network electrodes for high-rate electrochemical energy storage

    NASA Astrophysics Data System (ADS)

    Nguyen, Tuyen; Eugénio, Sónia; Boudard, Michel; Rapenne, Laetitia; Carmezim, M. João; Silva, Teresa M.; Montemor, M. Fátima

    2015-07-01

    This work reports the fabrication, by electrodeposition and post-thermal annealing, of hybrid electrodes for high rate electrochemical energy storage composed of nickel manganese oxide (Ni0.86Mn0.14O) nanosheets over 3D open porous dendritic NiCu foams. The hybrid electrodes are made of two different percolation networks of nanosheets and dendrites, and exhibit a specific capacitance value of 848 F g-1 at 1 A g-1. The electrochemical tests revealed that the electrodes display an excellent rate capability, characterized by capacitance retention of approximately 83% when the applied current density increases from 1 A g-1 to 20 A g-1. The electrodes also evidenced high charge-discharge cycling stability, which attained 103% after 1000 cycles.

  2. Large Scale 3-D Dislocation Dynamics and Atomistic Simulations of Flow and Strain-Hardening Behavior of Metallic Micropillars

    NASA Astrophysics Data System (ADS)

    Rao, Satish

    2015-03-01

    Experimental studies show strong strengthening effects for micrometer-scale FCC as well as two-phase superalloy crystals, even at high initial dislocation densities. This talk shows results from large-scale 3-D discrete dislocation simulations (DDS) used to explicitly model the deformation behavior of FCC Ni (flow stress and strain-hardening) as well as superalloy microcrystals for diameters ranging from 1 - 20 microns. The work shows that two size-sensitive athermal hardening processes, beyond forest and precipitation hardening, are sufficient to develop the dimensional scaling of the flow stress, stochastic stress variation, flow intermittency and, high initial strain-hardening rates, similar to experimental observations for various materials. In addition, 3D dislocation dynamics simulations are used to investigate strain-hardening characteristics and dislocation microstructure evolution with strain in large 20 micron size Ni microcrystals (bulk-like) under three different loading axes: 111, 001 and 110. Three different multi-slip loading axes, < 111 > , < 001 > and < 110 > , are explored for shear strains of ~0.03 and final dislocation densities of ~1013/m2. The orientation dependence of initial strain hardening rates and dislocation microstructure evolution with strain are discussed. The simulated strain hardening results are compared with experimental data under similar loading conditions from bulk single-crystal Ni. Finally, atomistic simulation results on the operation of single arm sources in Ni bipillars with a large angle grain boundary is discussed. The atomistic simulation results are compared with experimental mechanical behavior data on Cu bipillars with a similar large angle grain boundary. This work was supported by AFOSR (Dr. David Stargel), and by a grant of computer time from the DOD High Performance Computing Modernization Program, at the Aeronautical Systems Center/Major Shared Resource Center.

  3. A two-storey structured photoanode of a 3D Cu2ZnSnS4/CdS/ZnO@steel composite nanostructure for efficient photoelectrochemical hydrogen generation.

    PubMed

    Choi, Youngwoo; Baek, Minki; Zhang, Zhuo; Dao, Van-Duong; Choi, Ho-Suk; Yong, Kijung

    2015-10-01

    A two-storey structured photoanode of a 3D Cu2ZnSnS4(CZTS)/CdS/ZnO@steel composite nanostructure has been fabricated by using the solution method and demonstrated highly efficient photoelectrochemical hydrogen generation due to its contraption in the structure for sufficient light absorption as well as the three step-down band alignments for efficient charge separation and transport. This composite structure is composed of two storeys: the upper storey is the CZTS/CdS/ZnO hetero-nanorods (NRs) covered on the stainless steel mesh; the bottom storey is the CZTS/CdS/ZnO hetero-NRs grown on the FTO glass. The CZTS/CdS/ZnO hetero-NRs have cascade band gaps decreasing from 3.15 to 1.82 eV, which gives them efficient charge transfer and broad photoresponse in the UV to near-IR region, resulting in 47% IPCE in a wide light region from 400 to 500 nm; and the stainless steel mesh serves not only as a conductor for charge transport, but also as a skeleton of the grid structure for absorbing more light. The related mechanism has been investigated, which demonstrates that the two-storey CZTS/CdS/ZnO@steel composite nanostructure would have great potential as a promising photoelectrode with high efficiency and low cost for PEC hydrogen generation. PMID:26327311

  4. Free standing SnS2 nanosheets on 3D graphene foam: an outstanding hybrid nanostructure anode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Huang, Zhi Xiang; Wang, Ye; Wong, Jen It; Yang, Hui Ying

    2015-06-01

    Two-dimensional (2D) materials are attracting increased research interest due to their unique physical properties and potential for application in various electronic devices. Herein, the combination of 2D materials consisting of vertical aligned tin sulfide (SnS2) nanosheets and three-dimensional graphene (3DG) are designed as a superior functional anode material for energy storage devices using the merits of the two materials. The SnS2/3DG hybrid nanostructure was synthesized via a single-step solvothermal method and further used as a binder-free anode in lithium ion batteries (LIBs). The binder-free SnS2/3DG electrode shows excellent electrochemical performance including superior specific capacity, enhanced rate capability and outstanding cycling stability compared to pure SnS2 and 3DG. SnS2/3DG hybrid nanocomposite electrodes are able to deliver high reversible capacities of 771.2 mAh g-1 and 433.3 mAh g-1 at the current densities of 200 and 1000 mA g-1, respectively. The excellent electrochemical performance of SnS2/3DG nanocomposite is attributed to the synergistic effect between SnS2 and 3DG. These results demonstrate SnS2/3DG nanocomposites as a highly promising anode material for future generation LIBs.

  5. Microplasmas for direct, substrate-independent deposition of nanostructured metal oxides

    NASA Astrophysics Data System (ADS)

    Mackie, Katherine E.; Pebley, Andrew C.; Butala, Megan M.; Zhang, Jinping; Stucky, Galen D.; Gordon, Michael J.

    2016-07-01

    A general, substrate-independent method for plasma deposition of nanostructured, crystalline metal oxides is presented. The technique uses a flow-through, micro-hollow cathode plasma discharge (supersonic microplasma jet) with a "remote" ring anode to deliver a highly directed flux of growth species to the substrate. A diverse range of nanostructured materials (e.g., CuO, α-Fe2O3, and NiO) can be deposited on any room temperature surface, e.g., conductors, insulators, plastics, fibers, and patterned surfaces, in a conformal fashion. The effects of deposition conditions, substrate type, and patterning on film morphology, nanostructure, and surface coverage are highlighted. The synthesis approach presented herein provides a general and tunable method to deposit a variety of functional and hierarchical metal oxide materials on many different surfaces. High surface area, conversion-type CuO electrodes for Li-ion batteries are demonstrated as a proof-of-concept example.

  6. X-Ray Emission Spectra and Electronic Structures of Red Phosphorus, 3d Transition-Metal Phosphides and III V Compounds

    NASA Astrophysics Data System (ADS)

    Sugiura, Chikara

    1995-07-01

    The P Kβ emission spectra in fluorescence from red amorphous phosphorus, 3d transition-metal phosphides TiP, CrP, FeP, Fe2P, Fe3P, CoP, Co2P, Ni5P4, Ni2P, Ni3P, Cu3P, ZnP2 (black) and Zn3P2, and the semiconducting phosphides of the III-V type, BP, AlP, GaP and InP are measured with a high-resolution two-crystal vacuum spectrometer equipped with Ge(111) crystals. The influence of the metal atoms appears distinctly on the P Kβ fluorescence emission spectra. The measured spectra are compared with available X-ray emission and XPS valence-band spectra and theoretical energy-band calculations on a common energy scale. It is shown that considerable p-d, s mixing occurs in the valence bands of the 3d transition-metal phosphides and the P 3p states mix fairly with the P 3s states in the valence bands of red phosphorus, Gap and InP

  7. Localization of Metal Electrodes in the Intact Rat Brain Using Registration of 3D Microcomputed Tomography Images to a Magnetic Resonance Histology Atlas1,2,3

    PubMed Central

    Borg, Jana Schaich; Vu, Mai-Anh; Badea, Cristian; Badea, Alexandra; Johnson, G. Allan

    2015-01-01

    Abstract Simultaneous neural recordings taken from multiple areas of the rodent brain are garnering growing interest because of the insight they can provide about spatially distributed neural circuitry. The promise of such recordings has inspired great progress in methods for surgically implanting large numbers of metal electrodes into intact rodent brains. However, methods for localizing the precise location of these electrodes have remained severely lacking. Traditional histological techniques that require slicing and staining of physical brain tissue are cumbersome and become increasingly impractical as the number of implanted electrodes increases. Here we solve these problems by describing a method that registers 3D computed tomography (CT) images of intact rat brains implanted with metal electrode bundles to a magnetic resonance imaging histology (MRH) atlas. Our method allows accurate visualization of each electrode bundle’s trajectory and location without removing the electrodes from the brain or surgically implanting external markers. In addition, unlike physical brain slices, once the 3D images of the electrode bundles and the MRH atlas are registered, it is possible to verify electrode placements from many angles by “reslicing” the images along different planes of view. Furthermore, our method can be fully automated and easily scaled to applications with large numbers of specimens. Our digital imaging approach to efficiently localizing metal electrodes offers a substantial addition to currently available methods, which, in turn, may help accelerate the rate at which insights are gleaned from rodent network neuroscience. PMID:26322331

  8. RISK REDUCTION VIA GREENER SYNTHESIS OF NOBLE METAL NANOSTRUCTURES AND NANOCOMPOSITES

    EPA Science Inventory

    Aqueous preparation of nanoparticles using vitamins B2 and C which can function both as reducing and capping agents are described. Bulk and shape-controlled synthesis of noble nanostructures via microwave (MW)-assisted spontaneous reduction of noble metal salts using a-D-glucose,...

  9. Gas sensors based on one dimensional nanostructured metal-oxides: a review.

    PubMed

    Arafat, M M; Dinan, B; Akbar, Sheikh A; Haseeb, A S M A

    2012-01-01

    Recently one dimensional (1-D) nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO(2), TiO(2), In(2)O(3), WO(x), AgVO(3), CdO, MoO(3), CuO, TeO(2) and Fe(2)O(3). Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research. PMID:22969344

  10. Guided evolution of bulk metallic glass nanostructures: A platform for designing three-dimensional electrocatalytic surfaces

    DOE PAGESBeta

    Doubek, Gustavo; Sekol, Ryan C.; Li, Jinyang; Ryu, Won -Hee; Gittleson, Forrest S.; Nejati, Siamak; Moy, Eric; Reid, Candy; Carmo, Marcelo; Linardi, Marcelo; et al

    2015-12-22

    Precise control over catalyst surface composition and structure is necessary to improve the function of electrochemical systems. To that end, bulk metallic glass (BMG) alloys with atomically dispersed elements provide a highly processable, nanoscale platform for electrocatalysis and surface modification. Here we report on nanostructures of Pt-based BMGs that are modified with various subtractive and additive processes to improve their electrochemical performance.

  11. Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response

    SciTech Connect

    Kajita, Shin; Yoshida, Tomoko; Kitaoka, Daiki; Etoh, Reo; Yajima, Miyuki; Ohno, Noriyasu; Yoshida, Hisao; Yoshida, Naoaki; Terao, Yoshitaka

    2013-04-07

    It has been found recently that low-energy helium (He) plasma irradiation to tungsten (W) leads to the growth of W nanostructures on the surface. The process to grow the nanostructure is identified as a self-growth process of He bubbles and has a potential to open up a new plasma processing method. Here, we show that the metallic nanostructure formation process by the exposure to He plasma can occur in various metals such as, titanium, nickel, iron, and so on. When the irradiation conditions alter, the metallic cone arrays including nanobubbles inside are formed on the surface. Different from W cases, other processes than growth of fiberform structure, i.e., physical sputtering and the growth of large He bubbles, can be dominant on other metals during irradiation; various surface morphology changes can occur. The nanostructured W, part of which was oxidized, has revealed a significant photocatalytic activity under visible light (wavelength >700 nm) in decolorization of methylene blue without any co-catalyst.

  12. Nucleation engineered growth/formation of core-shell and hollow metal nanostructures

    NASA Astrophysics Data System (ADS)

    Nehra, Kamalesh; Verma, Manoj; Kumar, P. Senthil

    2016-05-01

    Herein, we present a simple yet versatile single step aqueous synthesis procedure for precisely controlling the formation of hollow as well as core-shell metal nanostructures. Modern refined Turkevich protocol has been effectively utilized so as to mechanistically understand the step-by-step autocatalytic process in the monodisperse synthesis of such exotic shaped metal nanostructures. Au core with Ag shell nanoparticles were optimized by the careful addition of Ag+ ions to the pristine gold nanoparticles, the negative charge on which efficiently attracts the Ag+-cations towards their surface and simultaneously reducing them, thereby consolidating the thin shell formation with ease. The shell thickness could as well be tuned by either changing the metal seed or cation concentration. Hollow Au nanostructures were obtained by the inverse addition of Au3+-anions to the as-prepared Ag nanoparticles, thus initiating the galvanic replacement process, wherein the concurrent oxidation of Ag0 and reduction of Au3+ takes place in a cohesive manner, resulting in the final etched nanoring / porous like morphology. The structure-property functional relationship of these artificial metal nanostructures were systematically studied utilizing optical absorption and microscopy techniques.

  13. Gas Sensors Based on One Dimensional Nanostructured Metal-Oxides: A Review

    PubMed Central

    Arafat, M. M.; Dinan, B.; Akbar, Sheikh A.; Haseeb, A. S. M. A.

    2012-01-01

    Recently one dimensional (1-D) nanostructured metal-oxides have attracted much attention because of their potential applications in gas sensors. 1-D nanostructured metal-oxides provide high surface to volume ratio, while maintaining good chemical and thermal stabilities with minimal power consumption and low weight. In recent years, various processing routes have been developed for the synthesis of 1-D nanostructured metal-oxides such as hydrothermal, ultrasonic irradiation, electrospinning, anodization, sol-gel, molten-salt, carbothermal reduction, solid-state chemical reaction, thermal evaporation, vapor-phase transport, aerosol, RF sputtering, molecular beam epitaxy, chemical vapor deposition, gas-phase assisted nanocarving, UV lithography and dry plasma etching. A variety of sensor fabrication processing routes have also been developed. Depending on the materials, morphology and fabrication process the performance of the sensor towards a specific gas shows a varying degree of success. This article reviews and evaluates the performance of 1-D nanostructured metal-oxide gas sensors based on ZnO, SnO2, TiO2, In2O3, WOx, AgVO3, CdO, MoO3, CuO, TeO2 and Fe2O3. Advantages and disadvantages of each sensor are summarized, along with the associated sensing mechanism. Finally, the article concludes with some future directions of research. PMID:22969344

  14. Dual-color encoded DNAzyme nanostructures for multiplexed detection of intracellular metal ions in living cells.

    PubMed

    Zhou, Wenjiao; Liang, Wenbing; Li, Daxiu; Yuan, Ruo; Xiang, Yun

    2016-11-15

    The detection of intracellular metal ions is of great importance in understanding metal homeostasis in cells and related diseases, and yet it remains a significant challenge to achieve this goal. Based on a new self-assembled and dual-color encoded DNAzyme nanostructure, we describe here an approach for multiplexed sensing of UO2(2+) and Pb(2+) in living cells. The fluorescently quenched nanoprobes can be prepared by simple thermal annealing of four ssDNAs containing the metal ion-dependent enzymatic and substrate sequences. The self-assembly formation of the nanostructures are verified by native polyacrylamide gel electrophoresis. The target metal ions can cleave the substrate sequences in the DNAzyme nanostructures to recover fluorescent emissions at different wavelengths for sensitive and selective in vitro multiplexed detection of UO2(2+) and Pb(2+) with the detection limits of 0.6nM and 3.9nM, respectively. Importantly, we demonstrate that these nanoprobes are stable in cell lysates and can enter cells without the aid of any transfection agents for simultaneous imaging intracellular UO2(2+) and Pb(2+). Moreover, the nanoprobes offer excellent biocompatibility and non-cytotoxicity. With these unique features, the dual-color encoded nanostructures presented here can thus offer new opportunities for multiplexed detection of specific intracellular species. PMID:27236722

  15. Extraction of 3d transition metals from molten cesium-sodium-potassium/acetate eutectic into dodecane using organophosphorous ligands

    SciTech Connect

    Maroni, V.A.; Philbin, C.E.; Yonco, R.M.

    1983-01-01

    Measurements have been made of the transfer of the transition metal cations Cr/sup 3 +/, Fe/sup 2 +/, Co/sup 2 +/, Ni/sup 2 +/ from molten cesium acetate-sodium acetate-potassium acetate eutectic (50-25-25 mol%, mp approx. 90/sup 0/C) into dodecane solutions containing selected acidic and neutral organophosphorous extracting ligands. The ordering of the transition metals according to their relative extents of extraction into the dodecane phase when the ligand bis(2-ethylhexyl)-phosphinic acid, H(DEPH), is employed (and the conditions of extraction are the same for each cation) is Co/sup 2 +/ > Fe/sup 2 +/ > Cr/sup 3 +/ > Ni/sup 2 +/. Comparisons of results obtained using the acidic ligand H(DEPH) and the neutral ligand tri-n-octylphosphine oxide, TOPO, indicate that the extractible TM complex does not contain acetate as a charge neutralizing ligand, but rather requires complete displacement of inner sphere acetate ions by protonated and/or deprotonated alkylphosphinate groups. The mechanism controlling the transfer kinetics has not been elucidated, but the rates of extraction from the acetate eutectic appear to be somewhat slower than has been observed for the extraction of transition metals from molten alkali metal thiocyanate and nitrate media at comparable temperatures, i.e., 140 ..-->.. 180/sup 0/C. 13 references, 2 figures, 2 tables.

  16. Extraction of 3d transition metals from molten cesium-sodium-potassium/acetate eutectic into dodecane using organophosphorous ligands

    SciTech Connect

    Maroni, V.A.; Philbin, C.E.; Yonco, R.M.

    1983-01-01

    Experimental results are reported for the transfer of the transition metal (TM) cations Cr/sup 3 +/, Fe/sup 2 +/, Co/sup 2 +/, Ni/sup 2 +/ from molten cesium acetate-sodium acetate-potassium acetate eutectic (50-25-25 mol%, mp approx. 90/sup 0/C) into dodecane solutions containing selected acidic and neutral organophosphorous extracting ligands. The ordering of the transition metals according to their relative extents of extraction into the dodecane phase when the ligand bis(2-ethylhexyl)-phosphinic acid, H(DEPH), is employed (and the conditions of extraction are the same for each cation) is Co/sup 2 +/ > Fe/sup 2 +/ > Cr/sup 3 +/ > Ni/sup 2 +/. Comparisons of results obtained using the acidic ligand H(DEPH) and the neutral ligand tri-n-octylphosphine oxide, TOPO, indicate that the extractible TM complex does not contain acetate as a charge neutralizing ligand, but rather requires complete displacement of inner sphere acetate ions by protonated and/or deprotonated alkylphosphinate groups. The mechanism controlling the transfer kinetics has not been elucidated, but the rates of extraction from the acetate eutectic appear to be somewhat slower than has been observed for the extraction of transition metals from molten alkali metal thiocyanate and nitrate media at comparable temperatures, i.e., 140 ..-->.. 180/sup 0/C. 13 references, 2 figures, 2 tables.

  17. Monitoring the formation of carbide crystal phases during the thermal decomposition of 3d transition metal dicarboxylate complexes

    SciTech Connect

    Huba, ZJ; Carpenter, EE

    2014-06-06

    Single molecule precursors can help to simplify the synthesis of complex alloys by minimizing the amount of necessary starting reagents. However, single molecule precursors are time consuming to prepare with very few being commercially available. In this study, a simple precipitation method is used to prepare Fe, Co, and Ni fumarate and succinate complexes. These complexes were then thermally decomposed in an inert atmosphere to test their efficiency as single molecule precursors for the formation of metal carbide phases. Elevated temperature X-ray diffraction was used to identify the crystal phases produced upon decomposition of the metal dicarboxylate complexes. Thermogravimetric analysis coupled with an infrared detector was used to identify the developed gaseous decomposition products. All complexes tested showed a reduction from the starting M2+ oxidation state to the M oxidation state, upon decomposition. Also, each complex tested showed CO2 and H2O as gaseous decomposition products. Nickel succinate, iron succinate, and iron fumarate complexes were found to form carbide phases upon decomposition. This proves that transition metal dicarboxylate salts can be employed as efficient single molecule precursors for the formation of metal carbide crystal phases.

  18. A compact quasi 3D threshold voltage modeling and performance analysis of a novel linearly graded binary metal alloy quadruple gate MOSFET for subdued short channel effects

    NASA Astrophysics Data System (ADS)

    Sarkhel, Saheli; Sarkar, Subir Kumar

    2015-06-01

    In the present era of low power devices, to keep pace with the aggressive scaling demands, the concept of surrounding gate MOS geometry is gradually being popular among the researchers for enhancing the performance of nanoscale MOSFETs due to the inherent benefit of the gate-all-around geometry compared to the conventional planar structures. In this research endeavour, we have, for the first time, incorporated the novel theory of work function engineering of a binary metal alloy gate with continuous horizontal variation of mole fraction in a fully depleted quadruple gate MOSFET, thereby proposing a new structure namely Work Function Engineered Gate Quadruple Gate MOSFET (WFEG QG MOSFET). A detailed analytical modeling of this novel WFEG QG MOS structure has been formulated to present a quasi 3D threshold voltage model based on 3D scaling equation instead of the tedious solution of 3D Poisson's equation. The device short channel effects have been included by calculating the natural length of the proposed QG device using the effective number of gate (ENG) concept. An overall comparative performance analysis of the WFEG QG MOS and normal QG MOSFET has been done to establish the superiority of the proposed WFEG structure over its QG equivalent in terms of reduced Short Channel Effects (SCEs), Drain Induced Barrier Lowering (DIBL) and Threshold Voltage Roll Off (TVRO). The results of our analytical modeling are found to be in good agreement with the simulation results, thereby establishing the accuracy of our modeling.

  19. CMOS-compatible metal-stabilized nanostructured Si as anodes for lithium-ion microbatteries

    NASA Astrophysics Data System (ADS)

    Lee, Gibaek; Schweizer, Stefan L.; Wehrspohn, Ralf B.

    2014-11-01

    The properties of fully complementary metal-oxide semiconductor (CMOS)-compatible metal-coated nanostructured silicon anodes for Li-ion microbatteries have been studied. The one-dimensional nanowires on black silicon (nb-Si) were prepared by inductively coupled plasma (ICP) etching and the metal (Au and Cu) coatings by successive magnetron sputtering technique. The Cu-coated nb-Si show the most promising electrochemical performance enhancements for the initial specific capacity as well as their cyclability compared to pristine nb-Si. The electrochemical and microstructural properties before and after cycling of the metal-coated nb-Si compared to their pristine counterparts are discussed in detail.

  20. 3 D characterization of gold nanoparticles supported on heavy metal oxide catalysts by HAADF-STEM electron tomography.

    PubMed

    González, J C; Hernández, J C; López-Haro, M; del Río, E; Delgado, J J; Hungría, A B; Trasobares, S; Bernal, S; Midgley, P A; Calvino, José Juan

    2009-01-01

    Living on the edge: Three-dimensional reconstructions from electron tomography data recorded from Au/Ce(0.50)Tb(0.12)Zr(0.38)O(2-x) catalysts show that gold nanoparticles (see picture; yellow) are preferentially located on stepped facets and nanocrystal boundaries. An epitaxial relationship between the metal and support plays a key role in the structural stabilization of the gold nanoparticles. PMID:19544338

  1. Facile synthesis of 3D few-layered MoS2 coated TiO2 nanosheet core-shell nanostructures for stable and high-performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chen, Biao; Zhao, Naiqin; Guo, Lichao; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

    2015-07-01

    Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications.Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy

  2. Filling the gap between the quantum and classical worlds of nanoscale magnetism: giant molecular aggregates based on paramagnetic 3d metal ions.

    PubMed

    Papatriantafyllopoulou, Constantina; Moushi, Eleni E; Christou, George; Tasiopoulos, Anastasios J

    2016-03-14

    In this review, aspects of the syntheses, structures and magnetic properties of giant 3d and 3d/4f paramagnetic metal clusters in moderate oxidation states are discussed. The term "giant clusters" is used herein to denote metal clusters with nuclearity of 30 or greater. Many synthetic strategies towards such species have been developed and are discussed in this paper. Attempts are made to categorize some of the most successful methods to giant clusters, but it will be pointed out that the characteristics of the crystal structures of such compounds including nuclearity, shape, architecture, etc. are unpredictable depending on the specific structural features of the included organic ligands, reaction conditions and other factors. The majority of the described compounds in this review are of special interest not only for their fascinating nanosized structures but also because they sometimes display interesting magnetic phenomena, such as ferromagnetic exchange interactions, large ground state spin values, single-molecule magnetism behaviour or impressively large magnetocaloric effects. In addition, they often possess the properties of both the quantum and the classical world, and thus their systematic study offers the potential for the discovery of new physical phenomena, as well as a better understanding of the existing ones. The research field of giant clusters is under continuous evolution and their intriguing structural characteristics and magnetism properties that attract the interest of synthetic Inorganic Chemists promise a brilliant future for this class of compounds. PMID:26767319

  3. On the size-dependent magnetism and all-optical magnetization switching of transition-metal silicide nanostructures

    SciTech Connect

    Glushkov, G. I.; Tuchin, A. V.; Popov, S. V.; Bityutskaya, L. A.

    2015-12-15

    Theoretical investigations of the electronic structure, synthesis, and all-optical magnetization switching of transition-metal silicide nanostructures are reported. The magnetic moment of the nanostructures is studied as a function of the silicide cluster size and configuration. The experimentally demonstrated magnetization switching of nanostructured nickel silicide by circularly polarized light makes it possible to create high-speed storage devices with high density data recording.

  4. Facile synthesis of 3D few-layered MoS₂ coated TiO₂ nanosheet core-shell nanostructures for stable and high-performance lithium-ion batteries.

    PubMed

    Chen, Biao; Zhao, Naiqin; Guo, Lichao; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Liu, Enzuo

    2015-08-14

    Uniform transition metal sulfide deposition on a smooth TiO2 surface to form a coating structure is a well-known challenge, caused mainly due to their poor affinities. Herein, we report a facile strategy for fabricating mesoporous 3D few-layered (<4 layers) MoS2 coated TiO2 nanosheet core-shell nanocomposites (denoted as 3D FL-MoS2@TiO2) by a novel two-step method using a smooth TiO2 nanosheet as a template and glucose as a binder. The core-shell structure has been systematically examined and corroborated by transmission electron microscopy, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. It is found that the resultant 3D FL-MoS2@TiO2 as a lithium-ion battery anode delivers an outstanding high-rate capability with an excellent cycling performance, relating to the unique structure of 3D FL-MoS2@TiO2. The 3D uniform coverage of few-layered (<4 layers) MoS2 onto the TiO2 can remarkably enhance the structure stability and effectively shortens the transfer paths of both lithium ions and electrons, while the strong synergistic effect between MoS2 and TiO2 can significantly facilitate the transport of ions and electrons across the interfaces, especially in the high-rate charge-discharge process. Moreover, the facile fabrication strategy can be easily extended to design other oxide/carbon-sulfide/oxide core-shell materials for extensive applications. PMID:26165623

  5. Extraction of 3d transition metals from molten cesium-sodium-potassium/acetate eutectic into dodecane using organophosphorous ligands

    SciTech Connect

    Maroni, V.A.; Philbin, C.E.; Yonco, R.M.

    1983-04-01

    Measurements have been made of the transfer of the transition metal cations Cr/sup 3 +/, Fe/sup 2 +/, Co/sup 2 +/, Ni/sup 2 +/ from molten cesium acetate-sodium acetate-potassium acetate eutectic (50-25-25 mol%, mp approx. 90/sup 0/C) into dodecane solutions containing selected acidic and neutral organophosphorous extracting ligands. The ordering of the relative rates and extents of extraction when the ligand bis(2-ethylhexyl)phosphinic acid, H(DEPH), is employed (and the conditions of extraction are the same for each cation) is Co/sup 2 +/ > Fe/sup 2 +/ > Cr/sup 3 +/ > Ni/sup 2 +/. Comparisons of results obtained using the acidic ligand H(DEPH) and the neutralligand Tri-n-octylphosphien oxide, TOPO, indicate that the extractible TM complex does not contain acetate as a charge neutralizing ligand, but rather requires complete displacement of inner sphere acetate ions by both protonated and deprotonated alkylphosphinate groups. In the case of Co/sup 2 +/, the extraction reaction involves the transformation of the cation from an octahedral ligand field in the acetate eutectic to a tetrahedral ligand field in the H(DEPH)/dodecane phase. The mechanism(s) controlling the transfer kinetics has not been elucidated, but it is noted that the rates of extraction from the acetate eutectic seem to be much slower than has been observed for extractions of transition metals from molten alkali metal thiocyanate and nitrate media over comparable temperature ranges (140 to 180/sup 0/C). 1 figure, 2 tables.

  6. Drag reduction using metallic engineered surfaces with highly ordered hierarchical topographies: nanostructures on micro-riblets

    NASA Astrophysics Data System (ADS)

    Kim, Taekyung; Shin, Ryung; Jung, Myungki; Lee, Jinhyung; Park, Changsu; Kang, Shinill

    2016-03-01

    Durable drag-reduction surfaces have recently received much attention, due to energy-saving and power-consumption issues associated with harsh environment applications, such as those experienced by piping infrastructure, ships, aviation, underwater vehicles, and high-speed ground vehicles. In this study, a durable, metallic surface with highly ordered hierarchical structures was used to enhance drag-reduction properties, by combining two passive drag-reduction strategies: an air-layer effect induced by nanostructures and secondary vortex generation by micro-riblet structures. The nanostructures and micro-riblet structures were designed to increase slip length. The top-down fabrication method used to form the metallic hierarchical structures combined laser interference lithography, photolithography, thermal reflow, nanoimprinting, and pulse-reverse-current electrochemical deposition. The surfaces were formed from nickel, which has high hardness and corrosion resistance, making it suitable for use in harsh environments. The drag-reduction properties of various metal surfaces were investigated based on the surface structure: a bare surface, a nanostructured surface, a micro-riblet surface, and a hierarchically structured surface of nanostructures on micro-riblets.

  7. The influence of 3d-impurities on magnetic and transport properties of CoSiB metallic glasses

    NASA Astrophysics Data System (ADS)

    Zakharenko, M.; Babich, M.; Yeremenko, G.; Semen'ko, M.

    2006-09-01

    Temperature dependencies of magnetic susceptibility and electric resistivity of Co-based metallic glasses (MGs) of the general composition CoMex(Si,B)28(Me=Fe,Cr,Si:B=18:10) have been studied up to 950 K. The studied MGs were found to be ferromagnets at the room temperature and their Curie point TC ranges within 260-560 K depending on the dopant contents. At the temperatures higher than TC, a wide paramagnetic region exists. The regularities of magnetic moment variation upon Cr doping evidence a formation of antiferromagnetic clusters, which determine the anomalous behavior of resistivity.

  8. Growth of 3-D flower/grass-like metal oxide nanoarchitectures based on catalyst-assisted oxidation method

    PubMed Central

    2014-01-01

    Cu2O grass-like and ZnO flower-like nanoarchitectures were fabricated directly on Cu powders and Zn powders using a novel thermal oxidation stress-induced (TOS) method based on catalyst assistance at a low temperature of 150°C under moderate humid atmosphere. The experiments of Al powder were also carried out based on TOS method. Overlapping migration (OLM) of Cu and Zn atoms and toothpaste squeezing migration (TSM) of Al atoms caused by different atom densities in metal oxide materials were studied. PACS 81. Materials science; 81.07.-b Nanoscale materials and structures: fabrication and characterization; 81.16.Hc Catalytic methods PMID:24624935

  9. Growth of 3-D flower/grass-like metal oxide nanoarchitectures based on catalyst-assisted oxidation method

    NASA Astrophysics Data System (ADS)

    Hu, Lijiao; Ju, Yang; Hosoi, Atsushi

    2014-03-01

    Cu2O grass-like and ZnO flower-like nanoarchitectures were fabricated directly on Cu powders and Zn powders using a novel thermal oxidation stress-induced (TOS) method based on catalyst assistance at a low temperature of 150°C under moderate humid atmosphere. The experiments of Al powder were also carried out based on TOS method. Overlapping migration (OLM) of Cu and Zn atoms and toothpaste squeezing migration (TSM) of Al atoms caused by different atom densities in metal oxide materials were studied.

  10. Shape-controlled continuous synthesis of metal nanostructures

    NASA Astrophysics Data System (ADS)

    Sebastian, Victor; Smith, Christopher D.; Jensen, Klavs F.

    2016-03-01

    A segmented flow-based microreactor is used for the continuous production of faceted nanocrystals. Flow segmentation is proposed as a versatile tool to manipulate the reduction kinetics and control the growth of faceted nanostructures; tuning the size and shape. Switching the gas from oxygen to carbon monoxide permits the adjustment in nanostructure growth from 1D (nanorods) to 2D (nanosheets). CO is a key factor in the formation of Pd nanosheets and Pt nanocubes; operating as a second phase, a reductant, and a capping agent. This combination confines the growth to specific structures. In addition, the segmented flow microfluidic reactor inherently has the ability to operate in a reproducible manner at elevated temperatures and pressures whilst confining potentially toxic reactants, such as CO, in nanoliter slugs. This continuous system successfully synthesised Pd nanorods with an aspect ratio of 6; thin palladium nanosheets with a thickness of 1.5 nm; and Pt nanocubes with a 5.6 nm edge length, all in a synthesis time as low as 150 s.A segmented flow-based microreactor is used for the continuous production of faceted nanocrystals. Flow segmentation is proposed as a versatile tool to manipulate the reduction kinetics and control the growth of faceted nanostructures; tuning the size and shape. Switching the gas from oxygen to carbon monoxide permits the adjustment in nanostructure growth from 1D (nanorods) to 2D (nanosheets). CO is a key factor in the formation of Pd nanosheets and Pt nanocubes; operating as a second phase, a reductant, and a capping agent. This combination confines the growth to specific structures. In addition, the segmented flow microfluidic reactor inherently has the ability to operate in a reproducible manner at elevated temperatures and pressures whilst confining potentially toxic reactants, such as CO, in nanoliter slugs. This continuous system successfully synthesised Pd nanorods with an aspect ratio of 6; thin palladium nanosheets with a

  11. Nano-structured noble metal catalysts based on hexametallate architecture for the reforming of hydrocarbon fuels

    DOEpatents

    Gardner, Todd H.

    2015-09-15

    Nano-structured noble metal catalysts based on hexametallate lattices, of a spinel block type, and which are resistant to carbon deposition and metal sulfide formation are provided. The catalysts are designed for the reforming of hydrocarbon fuels to synthesis gas. The hexametallate lattices are doped with noble metals (Au, Pt, Rh, Ru) which are atomically dispersed as isolated sites throughout the lattice and take the place of hexametallate metal ions such as Cr, Ga, In, and/or Nb. Mirror cations in the crystal lattice are selected from alkali metals, alkaline earth metals, and the lanthanide metals, so as to reduce the acidity of the catalyst crystal lattice and enhance the desorption of carbon deposit forming moieties such as aromatics. The catalysts can be used at temperatures as high as 1000.degree. C. and pressures up to 30 atmospheres. A method for producing these catalysts and applications of their use also is provided.

  12. Drawing the geometry of 3d transition metal-boron pairs in silicon from electron emission channeling experiments

    NASA Astrophysics Data System (ADS)

    Silva, D. J.; Wahl, U.; Correia, J. G.; Augustyns, V.; Lima, T. A. L.; Costa, A.; Bosne, E.; da Silva, M. R.; Araújo, J. P.; Pereira, L. M. C.

    2016-03-01

    Although the formation of transition metal-boron pairs is currently well established in silicon processing, the geometry of these complexes is still not completely understood. We investigated the lattice location of the transition metals manganese, iron, cobalt and nickel in n- and p+ -type silicon by means of electron emission channeling. For manganese, iron and cobalt, we observed an increase of sites near the ideal tetrahedral interstitial position by changing the doping from n- to p+ -type Si. Such increase was not observed for Ni. We ascribe this increase to the formation of pairs with boron, driven by Coulomb interactions, since the majority of iron, manganese and cobalt is positively charged in p+ -type silicon while Ni is neutral. We propose that breathing mode relaxation around the boron ion within the pair causes the observed displacement from the ideal tetrahedral interstitial site. We discuss the application of the emission channeling technique in this system and, in particular, how it provides insight on the geometry of such pairs.

  13. Magnetic properties of FeCu (3 d transition metals) SiB alloys with fine grain structure

    SciTech Connect

    Sawa, T. ); Takahashi, Y. )

    1990-05-01

    Soft magnetic properties were investigated together with crystallization process and grain size for FeCu (3{ital d} transition metals) SiB alloys with fine grains. They were rapidly quenched from the melt to achieve amorphous states and then annealed above their crystallization temperatures. In the group of 3{ital d} transition metals studied, low magnetic core loss at high frequency was obtained for V-substituted Fe-based alloys, because only a bcc Fe solid solution with diameter of about 20 nm precipitated. On the other hand, Cr- or Mn-substituted alloys could not be attained with good soft magnetic properties because of the existence of Fe-metalloid compounds besides the bcc phase by annealing above their crystallization temperatures. The effect of grain size on the soft magnetic properties is more prominent at lower frequency. Diffraction peaks which are characteristics of an ordered phase (DO{sub 3}) are observed, which is the origin of excellent soft magnetic properties in FeAlSi alloys.

  14. Electron energy-loss near-edge structures of 3d transition metal oxides recorded at high-energy resolution.

    PubMed

    Mitterbauer, C; Kothleitner, G; Grogger, W; Zandbergen, H; Freitag, B; Tiemeijer, P; Hofer, F

    2003-09-01

    Near-edge fine structures of the metal L(2,3) and O K-edges in transition metal-oxides have been studied with a transmission electron microscope equipped with a monochromator and a high-resolution imaging filter. This system enables the recording of EELS spectra with an energy resolution of 0.1eV thus providing new near-edge fine structure details which could not be observed previously by EELS in conventional TEM instruments. EELS-spectra from well-defined oxides like titanium oxide (TiO(2)), vanadium oxide (V(2)O(5)), chromium oxide (Cr(2)O(3)), iron oxide (Fe(2)O(3)), cobalt oxide (CoO) and nickel oxide (NiO) have been measured with the new system. These spectra are compared with EELS data obtained from a conventional microscope and the main spectral features are interpreted. Additionally, the use of monochromised TEMs is discussed in view of the natural line widths of K and L(2,3) edges. PMID:12871809

  15. Synthesis and mechanistic study of stable water-soluble noble metal nanostructures

    NASA Astrophysics Data System (ADS)

    Cai, Ling-Jian; Wang, Min; Hu, Yang; Qian, Dong-Jin; Chen, Meng

    2011-07-01

    Sodium salt of poly(4-styrenesulfonic acid-co-maleic acid) (PSSMA) has been employed to prepare a series of stable nanosized metal colloids such as silver, gold, palladium, platinum, and silver-gold alloy nanostructures. All of the as-synthesized products are very stable in water. The metal nanostructures have been directly confirmed by ultraviolet-visible spectroscopy, transmission electron microscopy (TEM), high-resolution TEM, and selected area electron diffraction (SAED), and also characterized by techniques such as Fourier transform infrared spectroscopy (FT-IR) and 1H NMR. Intensive study has found that the metal ions are most probably reduced by organic radicals, generated from the thermal degradation of PSSMA.

  16. Synthesis and Electrochemical Sensing Toward Heavy Metals of Bunch-like Bismuth Nanostructures

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi; Yu, Ke; Bai, Dan; Zhu, Ziqiang

    2010-02-01

    Large-scale bunch-like bismuth (Bi) nanostructures were the first time to be synthesized via two-step electrochemical deposition. The growth mechanism of the nanostructures was discussed. Such a designed bunch-like Bi electrode has high sensitivity to detect the heavy metal ions due to its unique three-dimensional structures and strong ability of adsorbing the heavy metal ions. The bunch-like Bi electrode’s detection of heavy metals was statically performed using anodic stripping voltammetry (ASV). The detection in the Pb(II) concentration range of 2.5-50 μg/l was also performed. Based on the experimental results, this bunch-like Bi electrode can be considered as an interesting alternative to common mercury electrodes and bismuth film electrodes for possible use in electrochemical studies and electroanalytical applications.

  17. Insights into the effects of metal nanostructuring and oxidation on the work function and charge transfer of metal/graphene hybrids.

    PubMed

    Giangregorio, M M; Jiao, W; Bianco, G V; Capezzuto, P; Brown, A S; Bruno, G; Losurdo, M

    2015-08-14

    Graphene/metal heterojunctions are ubiquitous in graphene-based devices and, therefore, have attracted increasing interest of researchers. Indeed, the literature on the field reports apparently contradictory results about the effect of a metal on graphene doping. Here, we elucidate the effect of metal nanostructuring and oxidation on the metal work function (WF) and, consequently, on the charge transfer and doping of graphene/metal hybrids. We show that nanostructuring and oxidation of metals provide a valid support to frame WF and doping variation in metal/graphene hybrids. Chemical vapour-deposited monolayer graphene has been transferred onto a variety of metal surfaces, including d-metals, such as Ag, Au, and Cu, and sp-metals, such as Al and Ga, configured as thin films or nanoparticle (NP) ensembles of various average sizes. The metal-induced charge transfer and the doping of graphene have been investigated using Kelvin probe force microscopy (KPFM), and corroborated by Raman spectroscopy and plasmonic ellipsometric spectroscopy. We show that when the appropriate WF of the metal is considered, without any assumption, taking into account WF variations by nanostructure and/or oxidation, a linear relationship between the metal WF and the doping of graphene is found. Specifically, for all metals, nanostructuring lowers the metal WF. In addition, using gold as an example, a critical metal nanoparticle size is found at which the direction of charge transfer, and consequently graphene doping, is inverted. PMID:26158222

  18. Shape-controlled continuous synthesis of metal nanostructures.

    PubMed

    Sebastian, Victor; Smith, Christopher D; Jensen, Klavs F

    2016-04-14

    A segmented flow-based microreactor is used for the continuous production of faceted nanocrystals. Flow segmentation is proposed as a versatile tool to manipulate the reduction kinetics and control the growth of faceted nanostructures; tuning the size and shape. Switching the gas from oxygen to carbon monoxide permits the adjustment in nanostructure growth from 1D (nanorods) to 2D (nanosheets). CO is a key factor in the formation of Pd nanosheets and Pt nanocubes; operating as a second phase, a reductant, and a capping agent. This combination confines the growth to specific structures. In addition, the segmented flow microfluidic reactor inherently has the ability to operate in a reproducible manner at elevated temperatures and pressures whilst confining potentially toxic reactants, such as CO, in nanoliter slugs. This continuous system successfully synthesised Pd nanorods with an aspect ratio of 6; thin palladium nanosheets with a thickness of 1.5 nm; and Pt nanocubes with a 5.6 nm edge length, all in a synthesis time as low as 150 s. PMID:26927867

  19. How light gets through periodically nanostructured metal films: a role of surface polaritonic crystals.

    PubMed

    Zayats, A V; Salomon, L; De Fornel, F

    2003-06-01

    The physical origin of the enhanced optical transmission of periodically structured films related to surface plasmon polaritons is discussed from first principles. The enhancement of transmission through smooth, randomly rough and periodically nanostructured films is considered. Analysis shows that any metal (or dielectric) nanostructured film can exhibit enhanced transmission in certain spectral ranges corresponding to surface plasmon (or phonon) polariton Bloch mode states on a periodic structure. Resonant tunnelling via these states is responsible for the transmission enhancement. The properties of surface polaritonic crystals are analogous to those of photonic crystals and can find numerous applications for scaling down optical devices to nanometric dimensions as well as for designing novel nanostructured materials whose optical properties are determined by surface polariton interaction in a periodic structure. PMID:12787112

  20. Control of Nanostructures and Interfaces of Metal Oxide Semiconductors for Quantum-Dots-Sensitized Solar Cells.

    PubMed

    Tian, Jianjun; Cao, Guozhong

    2015-05-21

    Nanostructured metal oxide semiconductors (MOS), such as TiO2 and ZnO, have been regarded as an attractive material for the quantum dots sensitized solar cells (QDSCs), owing to their large specific surface area for loading a large amount of quantum dots (QDs) and strong scattering effect for capturing a sufficient fraction of photons. However, the large surface area of such nanostructures also provides easy pathways for charge recombination, and surface defects and connections between adjacent nanoparticles may retard effective charge injection and charge transport, leading to a loss of power conversion efficiency. Introduction of the surface modification for MOS or QDs has been thought an effective approach to improve the performance of QDSC. In this paper, the recent advances in the control of nanostructures and interfaces in QDSCs and prospects for the further development with higher power conversion efficiency (PCE) have been discussed. PMID:26263261