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Sample records for 3d nanostructured metal

  1. One-step direct-laser metal writing of sub-100 nm 3D silver nanostructures in a gelatin matrix

    NASA Astrophysics Data System (ADS)

    Kang, SeungYeon; Vora, Kevin; Mazur, Eric

    2015-03-01

    Developing an ability to fabricate high-resolution, 3D metal nanostructures in a stretchable 3D matrix is a critical step to realizing novel optoelectronic devices such as tunable bulk metal-dielectric optical devices and THz metamaterial devices that are not feasible with alternative techniques. We report a new chemistry method to fabricate high-resolution, 3D silver nanostructures using a femtosecond-laser direct metal writing technique. Previously, only fabrication of 3D polymeric structures or single-/few-layer metal structures was possible. Our method takes advantage of unique gelatin properties to overcome such previous limitations as limited freedom in 3D material design and short sample lifetime. We fabricate more than 15 layers of 3D silver nanostructures with a resolution of less than 100 nm in a stable dielectric matrix that is flexible and has high large transparency that is well-matched for potential applications in the optical and THz metamaterial regimes. This is a single-step process that does not require any further processing. This work will be of interest to those interested in fabrication methods that utilize nonlinear light-matter interactions and the realization of future metamaterials.

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

    PubMed Central

    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. 3D Nanostructuring of Semiconductors

    NASA Astrophysics Data System (ADS)

    Blick, Robert

    2000-03-01

    Modern semiconductor technology allows to machine devices on the nanometer scale. I will discuss the current limits of the fabrication processes, which enable the definition of single electron transistors with dimensions down to 8 nm. In addition to the conventional 2D patterning and structuring of semiconductors, I will demonstrate how to apply 3D nanostructuring techniques to build freely suspended single-crystal beams with lateral dimension down to 20 nm. In transport measurements in the temperature range from 30 mK up to 100 K these nano-crystals are characterized regarding their electronic as well as their mechanical properties. Moreover, I will present possible applications of these devices.

  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. 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.

  6. 3D nanostructures fabricated by advanced stencil lithography.

    PubMed

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

    2016-03-07

    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.

  7. 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

  8. 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

    2015-11-10

    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.

  9. 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

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

    PubMed

    Vora, Kevin; Kang, SeungYeon; Mazur, Eric

    2012-11-27

    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

  11. A Method to Fabricate Disconnected Silver Nanostructures in 3D

    PubMed Central

    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 dot10,11or coupled metal rod12,13 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 form structures

  12. A 3D Nanostructure Based on Transition-Metal Phosphide Decorated Heteroatom-Doped Mesoporous Nanospheres Interconnected with Graphene: Synthesis and Applications.

    PubMed

    Qiu, Shuilai; Xing, Weiyi; Mu, Xiaowei; Feng, Xiaming; Ma, Chao; Yuen, Richard K K; Hu, Yuan

    2016-11-30

    A novel three-dimensional nanostructure based on cobalt phosphide nanoparticles (Co2P NPs) and heteroatom-doped mesoporous carbon spheres interconnected with graphene (3D PZM@Co2P@RGO) was facilely synthesized for the first time, and it was used for enhancing the flame retardancy and toxicity suppression of epoxy resins (EP) via a synergistic effect. Herein, the cross-linked polyphosphazene hollow spheres (PZM) were used as templates for the fabrication of 3D architecture. The 3D architecture based on Co2P-decorated heteroatom-doped carbon sphere and reduced graphene oxide was prepared via a carbonization procedure followed by a hydrothermal self-assembly strategy. The as-prepared material exhibits excellent catalytic activity with regard to the combustion process. Notably, inclusion of incorporating PZM@Co2P@RGO resulted in a dramatic reduction of the fire hazards of EP, such as a 47.9% maximum decrease in peak heat release rate and a 29.2% maximum decrease in total heat release, lower toxic CO yield, and formation of high-graphitized protective char layer. In addition, the mechanism for flame retardancy and toxicity suppression was proposed. It is reasonable to know that the improved flame-retardant performance for EP nanocomposites is attributed to tripartite cooperative effect from respective components (Co2P NPs and RGO) plus the heteroatom-doped carbon spheres.

  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. Nanostructured thick 3D nanofibrous scaffold can induce bone.

    PubMed

    Eap, Sandy; Morand, David; Clauss, François; Huck, Olivier; Stoltz, Jean-François; Lutz, Jean-Christophe; Gottenberg, Jacques-Eric; Benkirane-Jessel, Nadia; Keller, Laetitia; Fioretti, Florence

    2015-01-01

    Designing unique nanostructured biomimetic materials is a new challenge in modern regenerative medicine. In order to develop functional substitutes for damaged organs or tissues, several methods have been used to create implants able to regenerate robust and durable bone. Electrospinning produces nonwoven scaffolds based on polymer nanofibers mimicking the fibrillar organization of bone extracellular matrix. Here, we describe a biomimetic 3D thick nanofibrous scaffold obtained by electrospinning of the biodegradable, bioresorbable and FDA-approved polymer, poly(ε-caprolactone). Such scaffold presents a thickness reaching one centimeter. We report here the demonstration that the designed nanostructured implant is able to induce in vivo bone regeneration.

  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. Fabrication of tunable plasmonic 3D nanostructures for SERS applications

    NASA Astrophysics Data System (ADS)

    Ozbay, Ayse; Yuksel, Handan; Solmaz, Ramazan; Kahraman, Mehmet

    2016-03-01

    Surface-enhanced Raman scattering (SERS) is a powerful technique used for characterization of biological and nonbiological molecules and structures. Since plasmonic properties of the nanomaterials is one of the most important factor influencing SERS activity, tunable plasmonic properties (wavelength of the surface plasmons and magnitude of the electromagnetic field generated on the surface) of SERS substrates are crucial in SERS studies. SERS enhancement can be maximized by controlling of plasmonic properties of the nanomaterials. In this study, a novel approach to fabricate tunable plasmonic 3D nanostructures based on combination of soft lithography and nanosphere lithography is studied. Spherical latex particles having different diameters are uniformly deposited on glass slides with convective assembly method. The experimental parameters for the convective assembly are optimized by changing of latex spheres concentration, stage velocity and latex particles volume placed between to two glass slides that staying with a certain angle to each other. Afterwards, polydimethylsiloxane (PDMS) elastomer is poured on the deposited latex particles and cured to obtain nanovoids on the PDMS surfaces. The diameter and depth of the nanovoids on the PDMS surface are controlled by the size of the latex particles. Finally, fabricated nanovoid template on the PDMS surfaces are filled with the silver coating to obtain plasmonic 3D nanostructures. Characterization of the fabricated surfaces is performed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). SERS performance of fabricated 3D plasmonic nanostructures will be evaluated using Raman reporter molecules.

  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

    2016-07-12

    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. Supported 3-D Pt nanostructures: the straightforward synthesis and enhanced electrochemical performance for methanol oxidation in an acidic medium

    NASA Astrophysics Data System (ADS)

    Li, Zesheng; Ji, Shan; Pollet, Bruno G.; Shen, Pei Kang

    2013-10-01

    Noble metal nanostructures with branched morphologies [i.e., 3-D Pt nanoflowers (NFs)] by tri-dimensionally integrating onto conductive carbon materials are proved to be an efficient and durable electrocatalysts for methanol oxidation. The well-supported 3-D Pt NFs are readily achieved by an efficient cobalt-induced/carbon-mediated galvanic reaction approach. Due to the favorable nanostructures (3-D Pt configuration allowing a facile mass transfer) and supporting effects (including framework stabilization, spatially separate feature, and improved charge transport effects), these 3-D Pt NFs manifest much higher electrocatalytic activity and stability toward methanol oxidation than that of the commercial Pt/C and Pt-based electrocatalysts.

  20. 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.

  1. 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.

  2. 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.

  3. Development of a 3D-AFM for true 3D measurements of nanostructures

    NASA Astrophysics Data System (ADS)

    Dai, Gaoliang; Häßler-Grohne, Wolfgang; Hüser, Dorothee; Wolff, Helmut; Danzebrink, Hans-Ulrich; Koenders, Ludger; Bosse, Harald

    2011-09-01

    The development of advanced lithography requires highly accurate 3D metrology methods for small line structures of both wafers and photomasks. Development of a new 3D atomic force microscopy (3D-AFM) with vertical and torsional oscillation modes is introduced in this paper. In its configuration, the AFM probe is oscillated using two piezo actuators driven at vertical and torsional resonance frequencies of the cantilever. In such a way, the AFM tip can probe the surface with a vertical and a lateral oscillation, offering high 3D probing sensitivity. In addition, a so-called vector approach probing (VAP) method has been applied. The sample is measured point-by-point using this method. At each probing point, the tip is approached towards the surface until the desired tip-sample interaction is detected and then immediately withdrawn from the surface. Compared to conventional AFMs, where the tip is kept continuously in interaction with the surface, the tip-sample interaction time using the VAP method is greatly reduced and consequently the tip wear is reduced. Preliminary experimental results show promising performance of the developed system. A measurement of a line structure of 800 nm height employing a super sharp AFM tip could be performed with a repeatability of its 3D profiles of better than 1 nm (p-v). A line structure of a Physikalisch-Technische Bundesanstalt photomask with a nominal width of 300 nm has been measured using a flared tip AFM probe. The repeatability of the middle CD values reaches 0.28 nm (1σ). A long-term stability investigation shows that the 3D-AFM has a high stability of better than 1 nm within 197 measurements taken over 30 h, which also confirms the very low tip wear.

  4. Beta-MnO2 3D nanostructures: mineralizer-assisted synthesis, characterization, and growth mechanism.

    PubMed

    Zhou, Fu; Zhao, Xuemei; Yuan, Cunguang; Xu, Hai

    2007-09-01

    The beta-MnO2 three-dimensional (3D) nanostructures were synthesized in large area by a mineralizer-assisted hydrothermal route. KNO3 was introduced as inorganic mineralizer to direct the growth of beta-MnO2 3D nanostructures from Mn(NO3)2 solutions. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Possible growth mechanism of beta-MnO2 3D nanostructures was proposed based on comparative experiments, indicating that KNO3 mineralizer and the concentration of Mn(NO3)2 solution were the two decisive factors in the fabrication of beta-MnO2 3D nanostructures.

  5. 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.

  6. Preparation and photocatalytic activities of 3D flower-like CuO nanostructures

    NASA Astrophysics Data System (ADS)

    Qingfei, Fan; Qi, Lan; Meili, Zhang; Ximei, Fan; Zuowan, Zhou; Chaoliang, Zhang

    2016-08-01

    Hierarchical 3D flower-like CuO nanostructures on the Cu substrates were synthesized by a wet chemical method and subsequent heat treatment. The synthesis, structure and morphologies of obtained samples under different concentrations of Na2S2O3 were investigated in detail and the possible growth mechanisms of the 3D flower-like CuO nanostructures were discussed. Na2S2O3 plays a key role in the generation of the 3D flower-like CuO nanostructures. When the concentration of Na2S2O3 is more than 0.4 mol/L, the 3D flower-like CuO nanostructures can be prepared on the Cu foils. The photocatalytic performances were studied by analyzing the degradation of methyl orange (MO) in aqueous solution in the presence of hydroxide water (H2O2). The 3D flower-like CuO nanostructures exhibit higher photocatalytic activity (96.2% degradation rate) than commercial CuO particles (36.3% degradation rate). The origin of the higher photocatalytic activity of the 3D flower-like CuO nanostructures was also discussed. Project supported by the High-Tech Research and Development Program of China (No. 2009AA03Z427).

  7. 3-D aluminum nanostructure with microhole array synthesized by femtosecond laser radiation for enhanced light extinction.

    PubMed

    Mahmood, Abdul Salam; Venkatakrishnan, Krishnan; Tan, Bo

    2013-11-14

    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.

  8. 3-D aluminum nanostructure with microhole array synthesized by femtosecond laser radiation for enhanced light extinction

    NASA Astrophysics Data System (ADS)

    Mahmood, Abdul Salam; Venkatakrishnan, Krishnan; Tan, Bo

    2013-11-01

    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.

  9. 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

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

    SciTech Connect

    Phatak, Charudatta; Knoop, Ludvig de; Houdellier, Florent; Gatel, Christophe; Hytch, Martin J.; Masseboeuf, Aurelien

    2016-03-10

    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. Furthermore the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures.

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

    DOE PAGES

    Phatak, Charudatta; Knoop, Ludvig de; Houdellier, Florent; ...

    2016-03-10

    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 wellmore » 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. Furthermore the 3D reconstructions can then directly be visualized and used in the design of functional 3D architectures built using 1D nanostructures.« less

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

    SciTech Connect

    Phatak, C.; Knoop, L. de; 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.

  13. A Tunable 3D Nanostructured Conductive Gel Framework Electrode for High-Performance Lithium Ion Batteries.

    PubMed

    Shi, Ye; Zhang, Jun; Bruck, Andrea M; Zhang, Yiman; Li, Jing; Stach, Eric A; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S; Yu, Guihua

    2017-03-22

    This study develops a tunable 3D nanostructured conductive gel framework as both binder and conductive framework for lithium ion batteries. A 3D nanostructured gel framework with continuous electron pathways can provide hierarchical pores for ion transport and form uniform coatings on each active particle against aggregation. The hybrid gel electrodes based on a polypyrrole gel framework and Fe3 O4 nanoparticles as a model system in this study demonstrate the best rate performance, the highest achieved mass ratio of active materials, and the highest achieved specific capacities when considering total electrode mass, compared to current literature. This 3D nanostructured gel-based framework represents a powerful platform for various electrochemically active materials to enable the next-generation high-energy batteries.

  14. Polymeric photovoltaics with various metallic plasmonic nanostructures

    NASA Astrophysics Data System (ADS)

    Zeng, Beibei; Gan, Qiaoqiang; Kafafi, Zakya H.; Bartoli, Filbert J.

    2013-02-01

    Broadband light absorption enhancement is numerically investigated for the active light harvesting layer of an organic photovoltaic (OPV), which consists of a blend of poly(3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM). Periodic plasmonic nanostructures placed above and below the active layer incorporate Ag, Al, Au, or a combination of two different metals. Three dimensional (3D) full-field electromagnetic simulations are applied to determine the effect of varying the metal employed in the plasmonic nanostructures on the absorption enhancement of the OPV. In addition, the geometric parameters (e.g., film thickness, period, and diameter) of the symmetrically distributed top and bottom metal (Ag, Al, or Au) nanostructures were varied to optimize the device structure and delineate the mechanism(s) leading to the absorption enhancement. A spectrally broadband, polarization-insensitive, and wide-angle absorption enhancement is obtained using a double plasmonic nanostructure and is attributed to the combined excitation of localized and single-interface surface plasmon polariton modes. The total photon absorption of the OPV with the optimized double plasmonic Ag nanostructures was found to be enhanced by as much as 82.8% and 80.4% under normal (0°) and 60° light incidence, respectively.

  15. Flexible fabrication of multi-scale integrated 3D periodic nanostructures with phase mask

    NASA Astrophysics Data System (ADS)

    Yuan, Liang Leon

    Top-down fabrication of artificial nanostructures, especially three-dimensional (3D) periodic nanostructures, that forms uniform and defect-free structures over large area with the advantages of high throughput and rapid processing and in a manner that can further monolithically integrate into multi-scale and multi-functional devices is long-desired but remains a considerable challenge. This thesis study advances diffractive optical element (DOE) based 3D laser holographic nanofabrication of 3D periodic nanostructures and develops new kinds of DOEs for advanced diffracted-beam control during the fabrication. Phase masks, as one particular kind of DOE, are a promising direction for simple and rapid fabrication of 3D periodic nanostructures by means of Fresnel diffraction interference lithography. When incident with a coherent beam of light, a suitable phase mask (e.g. with 2D nano-grating) can create multiple diffraction orders that are inherently phase-locked and overlap to form a 3D light interference pattern in the proximity of the DOE. This light pattern is typically recorded in photosensitive materials including photoresist to develop into 3D photonic crystal nanostructure templates. Two kinds of advanced phase masks were developed that enable delicate phase control of multiple diffraction beams. The first exploits femtosecond laser direct writing inside fused silica to assemble multiple (up to nine) orthogonally crossed (2D) grating layers, spaced on Talbot planes to overcome the inherent weak diffraction efficiency otherwise found in low-contrast volume gratings. A systematic offsetting of orthogonal grating layers to establish phase offsets over 0 to pi/2 range provided precise means for controlling the 3D photonic crystal structure symmetry between body centered tetragonal (BCT) and woodpile-like tetragonal (wTTR). The second phase mask consisted of two-layered nanogratings with small sub-wavelength grating periods and phase offset control. That was

  16. Final report: high resolution lensless 3D imaging of nanostructures with coherent x-rays

    SciTech Connect

    Jacobsen, Chris

    2011-04-14

    This project helped pioneer the core capabilities of coherent diffraction imaging (CDI) using X rays at synchrotron light source facilities. We developed an apparatus that was used for CDI at the Advanced Light Source, and applied it to 2D and 3D imaging of nanostructures. We also explored a number of conceptual and computational issues on the reconstruction of CDI data.

  17. 3D nanostructure reconstruction based on the SEM imaging principle, and applications.

    PubMed

    Zhu, Fu-Yun; Wang, Qi-Qi; Zhang, Xiao-Sheng; Hu, Wei; Zhao, Xin; Zhang, Hai-Xia

    2014-05-09

    This paper addresses a novel 3D reconstruction method for nanostructures based on the scanning electron microscopy (SEM) imaging principle. In this method, the shape from shading (SFS) technique is employed, to analyze the gray-scale information of a single top-view SEM image which contains all the visible surface information, and finally to reconstruct the 3D surface morphology. It offers not only unobstructed observation from various angles but also the exact physical dimensions of nanostructures. A convenient and commercially available tool (NanoViewer) is developed based on this method for nanostructure analysis and characterization of properties. The reconstruction result coincides well with the SEM nanostructure image and is verified in different ways. With the extracted structure information, subsequent research of the nanostructure can be carried out, such as roughness analysis, optimizing properties by structure improvement and performance simulation with a reconstruction model. Efficient, practical and non-destructive, the method will become a powerful tool for nanostructure surface observation and characterization.

  18. Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions

    PubMed Central

    Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

    2016-01-01

    The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape. PMID:27924857

  19. Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions

    NASA Astrophysics Data System (ADS)

    Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

    2016-12-01

    The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.

  20. Electrohydrodynamic-assisted Assembly of Hierarchically Structured, 3D Crumpled Nanostructures for Efficient Solar Conversions.

    PubMed

    Ishihara, Hidetaka; Chen, Yen-Chang; De Marco, Nicholas; Lin, Oliver; Huang, Chih-Meng; Limsakoune, Vipawee; Chou, Yi-Chia; Yang, Yang; Tung, Vincent

    2016-12-07

    The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges. In particular, the crumpled nanostructures dynamically adapt to non-spherical, polyhedral shapes under continuous deposition, ultimately assembling into foam-like microstructures with a highly accessible surface area and spatially interconnected transport pathways. The implementation of such crumpled nanostructures as three-dimensional rear contacts for solar conversion applications realize benefits of a high aspect ratio, electrically addressable and energetically favorable interfaces, and substantial enhancement of both short-circuit currents and fill-factors compared to those made of planar graphene counterparts. Further, the 3D crumpled nanostructures may shed lights onto the development of effective electrocatalytic electrodes due to their open structure that simultaneously allows for efficient water flow and hydrogen escape.

  1. Corrosion-Mediated Self-Assembly (CMSA): Direct Writing Towards Sculpturing of 3D Tunable Functional Nanostructures.

    PubMed

    Wang, Jing; Ho, Ghim Wei

    2015-12-21

    Inexpensive and readily available metal foils have been extracted and sculptured into nanocomposites without the expense of applied energy. The unwanted corrosion phenomenon has been contrarily utilized to realize desirable 3D nanostructures through a corrosion-mediated self-assembly (CMSA) method, which is unattainable by conventional 2D patterning routes. By virtue of electrochemical dissolution/re-deposition initiated by brass corrosion, ionic derivatives (Zn(2+) and Cu(2+) ) are continuously supplied and seized by etchant ions (PO4 (3-) ) to self-assemble into well-defined nanocomposites. Beyond 3D geometry patterning, CMSA enables arbitrarily tailoring of structures and chemical compositions with in situ multiphase amalgamation of hybrid materials, which improves homogeneity and thus mitigates phase separation issues. Importantly, the CMSA technique is demonstrated on transition metals for functional photocatalytic applications.

  2. 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.

  3. From 1D and 2D ZnO nanostructures to 3D hierarchical structures with enhanced gas sensing properties.

    PubMed

    Alenezi, Mohammad R; Henley, Simon J; Emerson, Neil G; Silva, S Ravi P

    2014-01-07

    Facile and low cost hydrothermal routes are developed to fabricate three-dimensional (3D) hierarchical ZnO structures with high surface-to-volume ratios and an increased fraction of (0001) polar surfaces. Hierarchical ZnO nanowires (ZNWs) and nanodisks (ZNDs) assembled from initial ZnO nanostructures are prepared from sequential nucleation and growth following a hydrothermal process. These hierarchical ZnO structures display an enhancement of gas sensing performance and exhibit significantly improved sensitivity and fast response to acetone in comparison to other mono-morphological ZnO, such as nanoparticles, NWs, or NDs. In addition to the high surface-to-volume ratio due to its small size, the nanowire building blocks show the enhanced gas sensing properties mainly ascribed to the increased proportion of exposed active (0001) planes, and the formation of many nanojunctions at the interface between the initial ZnO nanostructure and secondary NWs. This work provides the route for structure induced enhancement of gas sensing performance by designing a desirable nanostructure, which could also be extended to synthesize other metal oxide nanostructures with superior gas sensing performance.

  4. 3D-nanostructured boron-doped diamond for microelectrode array neural interfacing.

    PubMed

    Piret, Gaëlle; Hébert, Clément; Mazellier, Jean-Paul; Rousseau, Lionel; Scorsone, Emmanuel; Cottance, Myline; Lissorgues, Gaelle; Heuschkel, Marc O; Picaud, Serge; Bergonzo, Philippe; Yvert, Blaise

    2015-06-01

    The electrode material is a key element in the design of long-term neural implants and neuroprostheses. To date, the ideal electrode material offering high longevity, biocompatibility, low-noise recording and high stimulation capabilities remains to be found. We show that 3D-nanostructured boron doped diamond (BDD), an innovative material consisting in a chemically stable material with a high aspect ratio structure obtained by encapsulation of a carbon nanotube template within two BDD nanolayers, allows neural cell attachment, survival and neurite extension. Further, we developed arrays of 20-μm-diameter 3D-nanostructured BDD microelectrodes for neural interfacing. These microelectrodes exhibited low impedances and low intrinsic recording noise levels. In particular, they allowed the detection of low amplitude (10-20 μV) local-field potentials, single units and multiunit bursts neural activity in both acute whole embryonic hindbrain-spinal cord preparations and long-term hippocampal cell cultures. Also, cyclic voltammetry measurements showed a wide potential window of about 3 V and a charge storage capacity of 10 mC.cm(-2), showing high potentiality of this material for neural stimulation. These results demonstrate the attractiveness of 3D-nanostructured BDD as a novel material for neural interfacing, with potential applications for the design of biocompatible neural implants for the exploration and rehabilitation of the nervous system.

  5. 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.

  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. Relation between 2D/3D chirality and the appearance of chiroptical effects in real nanostructures.

    PubMed

    Arteaga, Oriol; Sancho-Parramon, Jordi; Nichols, Shane; Maoz, Ben M; Canillas, Adolf; Bosch, Salvador; Markovich, Gil; Kahr, Bart

    2016-02-08

    The optical activity of fabricated metallic nanostructures is investigated by complete polarimetry. While lattices decorated with nanoscale gammadia etched in thin metallic films have been described as two dimensional, planar nanostructures, they are better described as quasi-planar structures with some three dimensional character. We find that the optical activity of these structures arises not only from the dissymmetric backing by a substrate but, more importantly, from the selective rounding of the nanostructure edges. A true chiroptical response in the far-field is only allowed when the gammadia contain these non-planar features. This is demonstrated by polarimetric measurements in conjunction with electrodynamical simulations based on the discrete dipole approximation that consider non-ideal gammadia. It is also shown that subtle planar dissymmetries in gammadia are sufficient to generate asymmetric transmission of circular polarized light.

  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

    2016-04-06

    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.

  9. Pd atomic chain formation as a result of submonolayer deposition of 3d metals on Pd(110).

    PubMed

    Wei, D H; Gao, C L; Zakeri, Kh; Przybylski, M

    2009-11-27

    Submonolayer deposition of 3d transition metals such as Cr, Mn, Fe, Co, and Ni on Pd(110) at room temperature causes the formation of monoatomic chains of Pd as identified with scanning tunneling microscopy and spectroscopy. In agreement with recent theoretical predictions [Phys. Rev. B 79, 155410 (2009)], the substitution of Pd substrate atoms with the deposited atoms of 3d metals is found to be responsible for the formation of Pd atomic chains. This finding clarifies the long-debated issue about the chemical composition of the atomic chains grown on Pd(110) and points out the intriguing processes in the formation of self-assembled and self-organized nanostructures.

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

    PubMed

    Joshi, Ravi K; Schneider, Jörg J

    2012-08-07

    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

  11. 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

  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. Implementation of virtual models from sheet metal forming simulation into physical 3D colour models using 3D printing

    NASA Astrophysics Data System (ADS)

    Junk, S.

    2016-08-01

    Today the methods of numerical simulation of sheet metal forming offer a great diversity of possibilities for optimization in product development and in process design. However, the results from simulation are only available as virtual models. Because there are any forming tools available during the early stages of product development, physical models that could serve to represent the virtual results are therefore lacking. Physical 3D-models can be created using 3D-printing and serve as an illustration and present a better understanding of the simulation results. In this way, the results from the simulation can be made more “comprehensible” within a development team. This paper presents the possibilities of 3D-colour printing with particular consideration of the requirements regarding the implementation of sheet metal forming simulation. Using concrete examples of sheet metal forming, the manufacturing of 3D colour models will be expounded upon on the basis of simulation results.

  14. 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.

  15. Metal oxide nanostructures with hierarchical morphology

    SciTech Connect

    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.

  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. 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.

  18. 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.

  19. Understanding the effects of dielectric medium, substrate, and depth on electric fields and SERS of quasi-3D plasmonic nanostructures.

    PubMed

    Xu, Jiajie; Kvasnička, Pavel; Idso, Matthew; Jordan, Roger W; Gong, Heng; Homola, Jiří; Yu, Qiuming

    2011-10-10

    The local electric field distribution and the effect of surface-enhanced Raman spectroscopy (SERS) were investigated on the quasi-3D (Q3D) plasmonic nanostructures formed by gold nanohole and nanodisc array layers physically separated by a dielectric medium. The local electric fields at the top gold nanoholes and bottom gold nanodiscs as a function of the dielectric medium, substrate, and depth of Q3D plasmonic nanostructures upon the irradiation of a 785 nm laser were calculated using the three-dimensional finite-difference time-domain (3D-FDTD) method. The intensity of the maximum local electric fields was shown to oscillate with the depth and the stronger local electric fields occurring at the top or bottom gold layer strongly depend on the dielectric medium, substrate, and depth of the nanostructure. This phenomenon was determined to be related to the Fabry-Pérot interference effect and the interaction of localized surface plasmons (LSPs). The enhancement factors (EFs) of SERS obtained from the 3D-FDTD simulations were compared to those calculated from the SERS experiments conducted on the Q3D plasmonic nanostructures fabricated on silicon and ITO coated glass substrates with different depths. The same trend was obtained from both methods. The capabilities of tuning not only the intensity but also the location of the maximum local electric fields by varying the depth, dielectric medium, and substrate make Q3D plasmonic nanostructures well suited for highly sensitive and reproducible SERS detection and analysis.

  20. Au or Ag nanoparticle-decorated 3D urchin-like TiO2 nanostructures: synthesis, characterization, and enhanced photocatalytic activity.

    PubMed

    Xiang, Liqin; Zhao, Xiaopeng; Shang, Chaohong; Yin, Jianbo

    2013-08-01

    The semiconductors decorated with noble metals have attracted increasing attention due to their interesting physical and chemical properties. Here, 3D urchin-like hierarchical TiO2 nanostructures decorated with Au or Ag nanoparticles were prepared by wet-chemical process. The morphology and structure were characterized by different techniques. It shows that Au or Ag nanoparticles with narrow distribution are uniformly loaded on urchin-like TiO2 nanostructures, and the resulted composite nanostructures show distinct surface plasmon absorption band and quenched photoluminence compared to pure TiO2 nanostructures. Photocatalytic tests show both Au-decorated TiO2 and Ag-decorated TiO2 exhibit enhanced photocatalytic activity for photodegradation of methyl blue in water.

  1. 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.

  2. 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.

  3. Characterization Of Deformation Properties Of Metals In 3D ICs

    NASA Astrophysics Data System (ADS)

    Wittler, Olaf; Mroßko, Raul; Huber, Saskia; Dowhan, Lukasz; Lang, Klaus-Dieter

    2011-09-01

    The properties of the materials involved in the set-up of 3D ICs need to be known, when the occurring mechanical stresses are to be modeled. Especially elastic-plastic properties are relevant for the metal layers, which form redistribution layers and the through silicon vias. These can be characterized by the nanoindentation experiment, which is an established technique for the determination of Hardness and Young's modulus of thin films. But this standard data set is not sufficient to be used as input to finite element simulations, because stress strain curves are required for the analysis of reliability of metal layers. These stress-strain curves can be obtained by fitting the force displacement curves of the experiment with a finite-element model. This approach enables additionally a solution for the so called substrate effect, because the stiffness of the substrate can be considered in the fitting model. This known approach is being applied and tested on thin (300 nm) gold layers deposited on silicon. It is shown that a good sensitivity for Young's Modulus can be reached even for indents that exceed 10% of the film thickness, but for the plastic data the results are not unique and a range of plastic properties can be fitted.

  4. 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.

  5. Hydrothermal synthesis, characterization and optical properties of 3D flower like indium sulfide nanostructures

    NASA Astrophysics Data System (ADS)

    Ghaderi Sheikhi abadi, Parvaneh; Salavati-Niasari, Masoud; Davar, Fatemeh

    2013-01-01

    High-quality and high-yield 3D flower like indium sulfide (In2S3) nanostructures with cubic structure were synthesized by a wet chemical route, without using any surfactant and organic solvents at 160 °C for 12 h, by using InCl3 and 2-aminothiophenol (2-ATP) as starting reagents. The obtained In2S3 with different morphologies and size was characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible (UV-vis) spectroscopy. The effects of reaction parameters, such as temperature, precursor concentration and reaction time on the morphology, and particle size of products were investigated. Our experimental results showed that temperature and time reaction played key roles in the final morphology of In2S3. The morphology of In2S3 structures could be changed from one-dimensional (1D) structures to three-dimensional (3D) structures by increasing reaction time to 24 h. In the present study the optical properties 3D In2S3 structures were investigated.

  6. Jumplike microdeformation of nanostructured metals

    NASA Astrophysics Data System (ADS)

    Peschanskaya, N. N.; Smirnov, B. I.; Shpeĭzman, V. V.

    2008-05-01

    The parameters of microdeformation jumps for copper, aluminum, titanium, and Armco iron with the initial (annealed) structure and after equal-channel angular pressing are investigated in a creep mode under low compressive stresses. The strain rate is measured with a laser interferometer in 0.15-μm linear displacements. It is demonstrated that the values of the microstrain rate and the mean sizes of jumps for the annealed metals are larger than those for the metals subjected to severe deformation. It is revealed that there is a correlation between the jumps of microplastic deformation and the size of nanometal grains. The inference is made that, for nanostructured metals, as for other materials, the structural heterogeneity is one of the factors responsible for the jumplike deformation.

  7. 3D printing technology using high viscous materials - Synthesis of functional materials and fabrication of 3D metal structure

    NASA Astrophysics Data System (ADS)

    Hong, Seongik

    In the 3D printing technology, the research for using various materials has been performing. In this research work, 3D printable high viscous materials are suggested as one of the solutions for problems in the traditional 3D printing technology. First, Cu-Ag coreshell was synthesized as a functional material. In terms of the reaction rate, reaction rate limiting step was defined as a fundamental research, and then prepared Cu-Ag coreshell was printed and analyzed. Second, the high viscous Cu paste was prepared and then metal 3D printed structure was fabricated by using new printing method. In the synthesis of Cu-Ag coreshell, different sizes of Cu particle, 2μm and 100nm were used, and when 2μm Cu was applied, the reaction rate was limited by film diffusion control. However, when 100nm Cu was applied, reaction rate was controlled by CuO film and the rate of the reaction, which includes removing CuO film in the solution, is limited by chemical reaction control. The shape of Cu-Ag particle is spherical in the 2μm Cu condition and dendrite shape in the 100nm Cu condition respectively. The conductivity of Cu-Ag coreshell paste increased as increasing content of coreshell particle in the paste and sintering temperature. In order to print high viscous metal paste, the high viscous Cu paste was printed by using screw extruder, and the viscosity of Cu paste was measured as a fundamental research. As increasing wt.% of Cu in the paste, the viscosity also increased. In addition, the shrinkage factor was reduced by increasing wt.% of Cu in the paste. An optimized printing condition for the high viscous material was obtained, and by using this condition, 3D metal structure was fabricated. The final product was heat treated and polished. Through these processes, a fine quality of metal 3D structure was printed.

  8. Review on Chalcogenide 3D Nano-structured Crystals: Synthesis and Growth Mechanism.

    PubMed

    Qiu, Qi

    2015-01-01

    Three dimensional (3D) nano-structured crystals have received extensive attention for their superior properties over zero dimensional (0D), one dimensional (1D), or two dimensional (2D) nanomaterials in many areas. This review is generalized for the group of chalcogenide nanoflowers (NFs) by the synthetic techniques, such as solvothermal, wet chemical, sol-gel, surface oxidation, microwave, coating, electrochemical, and several other methods. The formation mechanism was also described for the purpose of opening up new food for thoughts to bring up new functionality of materials by tuning the morphology of crystals. The pH value or the template plays fundamental role in forming the nano-flowered structure. Moreover, the correlations between the surface area (SA), contact angle (CA), and the NFs are also discussed within the context. Here, we also discussed some patents relevant to the topic.

  9. 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.

  10. 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.

  11. 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.

  12. α-Fe2O3/TiO2 3D hierarchical nanostructures for enhanced photoelectrochemical water splitting.

    PubMed

    Han, Hyungkyu; Riboni, Francesca; Karlicky, Frantisek; Kment, Stepan; Goswami, Anandarup; Sudhagar, Pitchaimuthu; Yoo, Jeongeun; Wang, Lei; Tomanec, Ondrej; Petr, Martin; Haderka, Ondrej; Terashima, Chiaki; Fujishima, Akira; Schmuki, Patrik; Zboril, Radek

    2017-01-07

    We report the fabrication of 3D hierarchical hetero-nanostructures composed of thin α-Fe2O3 nanoflakes branched on TiO2 nanotubes. The novel α-Fe2O3/TiO2 hierarchical nanostructures, synthesized on FTO through a multi-step hydrothermal process, exhibit enhanced performances in photo-electrochemical water splitting and in the photocatalytic degradation of an organic dye, with respect to pure TiO2 nanotubes. An enhanced separation of photogenerated charge carriers is here proposed as the main factor for the observed photo-activities: electrons photogenerated in TiO2 are efficiently collected at FTO, while holes are transferred to the α-Fe2O3 nanobranches that serve as charge mediators to the electrolyte. The morphology of α-Fe2O3 that varies from ultrathin nanoflakes to nanorod/nanofiber structures depending on the Fe precursor concentration was shown to have a significant impact on the photo-induced activity of the α-Fe2O3/TiO2 composites. In particular, it is shown that for an optimized photo-electrochemical structure, a combination of critical factors should be achieved such as (i) TiO2 light absorption and photo-activation vs.α-Fe2O3-induced shadowing effect and (ii) the availability of free TiO2 surface vs.α-Fe2O3-coated surface. Finally, theoretical analysis, based on DFT calculations, confirmed the optical properties experimentally determined for the α-Fe2O3/TiO2 hierarchical nanostructures. We anticipate that this new multi-step hydrothermal process can be a blueprint for the design and development of other hierarchical heterogeneous metal oxide electrodes suitable for photo-electrochemical applications.

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

    PubMed

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

    2015-09-02

    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.

  14. 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.

  15. Predicting the band gap of ternary oxides containing 3d10 and 3d0 metals

    NASA Astrophysics Data System (ADS)

    McLeod, J. A.; Moewes, A.; Zatsepin, D. A.; Kurmaev, E. Z.; Wypych, A.; Bobowska, I.; Opasinska, A.; Cholakh, S. O.

    2012-11-01

    We present soft x-ray spectroscopy measurements and electronic structure calculations of ZnTiO3, a ternary oxide that is related to wurtzite ZnO and rutile TiO2. The electronic structure of ZnTiO3 was calculated using a variety of exchange-correlation functionals, and we compare the predicted band gaps of this material obtained from each functional with estimates from our experimental data and optical gaps quoted from the literature. We find that the main hybridizations in the electronic structure of ZnTiO3 can be predicted from the electronic structures of the two binary oxides. We further find that ZnTiO3 has weaker O 2p-Zn 3d repulsion than in ZnO, resulting in a relatively lower valence band maximum and consequently a larger band gap. Although we find a significant core hole shift in the measured O K XAS of ZnTiO3, we provide a simple empirical scheme for estimating the band gap that may prove to be applicable for any d10-d0 ternary oxide, and could be useful in finding a ternary oxide with a band gap tailored to a specific energy.

  16. 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.

  17. 3D and 2D structural characterization of 1D Al/Al2 O3 biphasic nanostructures.

    PubMed

    Miró, M Martinez; Veith, M; Lee, J; Soldera, F; Mücklich, F; Bennewitz, R; Aktas, C

    2015-05-01

    1D Al/Al2 O3 nanostructures have been synthesized by chemical vapour deposition (CVD) of the molecular precursor [(t) BuOAlH2 ]2 . The deposited nanostructures grow chaotically on the substrate forming a layer with a high porosity (80%). Depending on the deposition time, diverse nanostructured surfaces with different distribution densities were achieved. A three-dimensional (3D) reconstruction has been evaluated for every nanostructure density using the Focus Ion Beam (FIB) tomography technique and reconstruction software tools. Several structural parameters such as porosity, Euler number, geometrical tortuosity and aspect ratio have been quantified through the analysis with specified software of the reconstructions. Additionally roughness of the prepared surfaces has been characterized at micro- and nanoscale using profilometry and AFM techniques, respectively. While high aspects ratio around 20-30 indicates a strong anisotropy in the structure, high porosity values (around 80%) is observed as a consequence of highly tangled geometry of such 1D nanostructures.

  18. Metallic Nanostructures Based on DNA Nanoshapes

    PubMed Central

    Shen, Boxuan; Tapio, Kosti; Linko, Veikko; Kostiainen, Mauri A.; Toppari, Jari Jussi

    2016-01-01

    Metallic nanostructures have inspired extensive research over several decades, particularly within the field of nanoelectronics and increasingly in plasmonics. Due to the limitations of conventional lithography methods, the development of bottom-up fabricated metallic nanostructures has become more and more in demand. The remarkable development of DNA-based nanostructures has provided many successful methods and realizations for these needs, such as chemical DNA metallization via seeding or ionization, as well as DNA-guided lithography and casting of metallic nanoparticles by DNA molds. These methods offer high resolution, versatility and throughput and could enable the fabrication of arbitrarily-shaped structures with a 10-nm feature size, thus bringing novel applications into view. In this review, we cover the evolution of DNA-based metallic nanostructures, starting from the metallized double-stranded DNA for electronics and progress to sophisticated plasmonic structures based on DNA origami objects. PMID:28335274

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

    PubMed

    Yuan, Liang Leon; Herman, Peter R

    2016-02-29

    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.

  20. 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.

  1. 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

  2. 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

  3. Fabrication of complex metallic nanostructures by nanoskiving.

    PubMed

    Xu, Qiaobing; Rioux, Robert M; Whitesides, George M

    2007-10-01

    This paper describes the use of nanoskiving to fabricate complex metallic nanostructures by sectioning polymer slabs containing small, embedded metal structures. This method begins with the deposition of thin metallic films on an epoxy substrate by e-beam evaporation or sputtering. After embedding the thin metallic film in an epoxy matrix, sectioning (in a plane perpendicular or parallel to the metal film) with an ultramicrotome generates sections (which can be as thin as 50 nm) of epoxy containing metallic nanostructures. The cross-sectional dimensions of the metal wires embedded in the resulting thin epoxy sections are controlled by the thickness of the evaporated metal film (which can be as small as 20 nm) and the thickness of the sections cut by the ultramicrotome; this work uses a standard 45 degrees diamond knife and routinely generates slabs 50 nm thick. The embedded nanostructures can be transferred to, and positioned on, planar or curved substrates by manipulating the thin polymer film. Removal of the epoxy matrix by etching with an oxygen plasma generates free-standing metallic nanostructures. Nanoskiving can fabricate complex nanostructures that are difficult or impossible to achieve by other methods of nanofabrication. These include multilayer structures, structures on curved surfaces, structures that span gaps, structures in less familiar materials, structures with high aspect ratios, and large-area structures comprising two-dimensional periodic arrays. This paper illustrates one class of application of these nanostructures: frequency-selective surfaces at mid-IR wavelengths.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Metallic glass nanostructures: fabrication, properties, and applications.

    PubMed

    Liu, Lianci; Hasan, Molla; Kumar, Golden

    2014-02-21

    Remarkable progress has been made in fabrication and characterization of metal nanostructures because of their crucial role in energy conversion, nanophotonics, nanoelectronics, and biodiagnostics. Less emphasis has been placed on the synthesis of nanostructures from metallic alloys, which are better suited than elemental metals for certain applications such as fuel-cell catalysts. The main challenges in fabrication of alloy nanostructures are controlling their chemical stoichiometry, crystal structures, and shapes because of anisotropic nucleation and growth rates. These limitations can be overcome by using metallic glasses (amorphous metal alloys) which are isotropic and provide additional control handles through their tunable compositions and degree of crystallinity. Here, we review the recent developments in fabrication and characterization of metallic glass (MG) nanostructures. The focus is on sub-micron structures synthesized by unconventional thermoplastic techniques. A concept of self-assembly is introduced for fashioning functional structures using MG nanostructures as building blocks. The article concludes with a brief discussion about unique properties and prospective applications of MG nanostructures.

  9. Electrodeposition-based 3D Printing of Metallic Microarchitectures with Controlled Internal Structures.

    PubMed

    Seol, Seung Kwon; Kim, Daeho; Lee, Sanghyeon; Kim, Jung Hyun; Chang, Won Suk; Kim, Ji Tae

    2015-08-26

    3D printing of metallic microarchitectures with controlled internal structures is realized at room temperature in ambient air conditions by the manipulation of metal ion concentration and pulsed electric potentials in the electrolyte meniscus during the meniscus-guided electrodeposition. Precise control of the printing nozzle enables the drawing of complex 3D microarchitectures with well-defined geometries and positions.

  10. Direct Fabrication of 3D Metallic Networks and Their Performance.

    PubMed

    Ron, Racheli; Gachet, David; Rechav, Katya; Salomon, Adi

    2017-02-01

    Fabrication of macroscopic nanoporous metallic networks is challenging, because it demands fine structures at the nanoscale over a large-scale. A technique to form pure scalable networks is introduced. The networked-metals ("Netals") exhibit a strong interaction with light and indicate a large fraction of hot-electrons generation. These hot-electrons are available to derive photocatalytic processes.

  11. In situ fabrication of 3D Ag@ZnO nanostructures for microfluidic surface-enhanced Raman scattering systems.

    PubMed

    Xie, Yuliang; Yang, Shikuan; Mao, Zhangming; Li, Peng; Zhao, Chenglong; Cohick, Zane; Huang, Po-Hsun; Huang, Tony Jun

    2014-12-23

    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 ∼2×10(6) 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.

  12. 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

  13. Toward 3D Printing of Pure Metals by Laser-Induced Forward Transfer.

    PubMed

    Visser, Claas Willem; Pohl, Ralph; Sun, Chao; Römer, Gert-Willem; Huis in 't Veld, Bert; Lohse, Detlef

    2015-07-15

    3D printing of common metals is highly challenging because metals are generally solid at room conditions. Copper and gold pillars are manufactured with a resolution below 5 μm and a height up to 2 mm, using laser-induced forward transfer to create and eject liquid metal droplets. The solidified drop's shape is crucial for 3D printing and is discussed as a function of the laser energy.

  14. 3D amino-induced electroless plating: a powerful toolset for localized metallization on polymer substrates.

    PubMed

    Garcia, Alexandre; Berthelot, Thomas; Viel, Pascal; Jégou, Pascale; Palacin, Serge

    2011-11-18

    The "3D amino-induced electroless plating" (3D-AIEP) process is an easy and cost-effective way to produce metallic patterns onto flexible polymer substrates with a micrometric resolution and based on the direct printing of the mask with a commercial printer. Its effectiveness is based on the covalent grafting onto substrates of a 3D polymer layer which presents the ability to entrap Pd species. Therefore, this activated Pd-loaded and 3D polymer layer acts both as a seed layer for electroless metal growth and as an interdigital layer for enhanced mechanical properties of the metallic patterns. Consequently, flexible and transparent poly(ethylene terephtalate) (PET) sheets were selectively metalized with nickel or copper patterns. The electrical properties of the obtained metallic patterns were also studied.

  15. Density functional theory optimized basis sets for gradient corrected functionals: 3d transition metal systems.

    PubMed

    Calaminici, Patrizia; Janetzko, Florian; Köster, Andreas M; Mejia-Olvera, Roberto; Zuniga-Gutierrez, Bernardo

    2007-01-28

    Density functional theory optimized basis sets for gradient corrected functionals for 3d transition metal atoms are presented. Double zeta valence polarization and triple zeta valence polarization basis sets are optimized with the PW86 functional. The performance of the newly optimized basis sets is tested in atomic and molecular calculations. Excitation energies of 3d transition metal atoms, as well as electronic configurations, structural parameters, dissociation energies, and harmonic vibrational frequencies of a large number of molecules containing 3d transition metal elements, are presented. The obtained results are compared with available experimental data as well as with other theoretical data from the literature.

  16. Impact of 3D Hierarchical Nanostructures on the Antibacterial Efficacy of a Bacteria-Triggered Self-Defensive Antibiotic Coating.

    PubMed

    Hizal, Ferdi; Zhuk, Iryna; Sukhishvili, Svetlana; Busscher, Henk J; van der Mei, Henny C; Choi, Chang-Hwan

    2015-09-16

    Titanium is often applied in implant surgery, but frequently implicated in infections associated with bacterial adhesion and growth on the implant surface. Here, we show that hierarchical nanostructuring of titanium and the subsequent coating of resulting topographical features with a self-defensive, antibacterial layer-by-layer (LbL) film enables a synergistic action of hierarchical nanotopography and localized, bacteria-triggered antibiotic release to dramatically enhance the antibacterial efficiency of surfaces. Although sole nanostructuring of titanium substrates did not significantly affect adhesion and growth of Staphylococcus aureus, the coating of 3D-nanopillared substrates with an ultrathin tannic acid/gentamicin (TA/G) LbL film resulted in a 10-fold reduction of the number of surface-attached bacteria. This effect is attributed to the enlarged surface area of the nanostructured coating available for localized bacteria-triggered release of antibiotics, as well as to the lower bacterial adhesion forces resulting in subsided activation of bacterial antibiotic-defense mechanisms when bacteria land on nanopillar tips. The result shows that a combination of 3D nanostructuring with a bacteria-triggered antibiotic-releasing coating presents a unique way to dramatically enhance antibacterial efficacy of biomaterial implants.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. Coherent 3D nanostructure of γ-Al2O3: Simulation of whole X-ray powder diffraction pattern

    NASA Astrophysics Data System (ADS)

    Pakharukova, V. P.; Yatsenko, D. A.; Gerasimov, E. Yu.; Shalygin, A. S.; Martyanov, O. N.; Tsybulya, S. V.

    2017-02-01

    The structure and nanostructure features of nanocrystalline γ-Al2O3 obtained by dehydration of boehmite with anisotropic platelet-shaped particles were investigated. The original models of 3D coherent nanostructure of γ-Al2O3 were constructed. The models of nanostructured γ-Al2O3 particles were first confirmed by a direct simulation of powder X-Ray diffraction (XRD) patterns using the Debye Scattering Equation (DSE) with assistance of high-resolution transmission electron microscopy (HRTEM) study. The average crystal structure of γ-Al2O3 was shown to be tetragonally distorted. The experimental results revealed that thin γ-Al2O3 platelets were heterogeneous on a nanometer scale and nanometer-sized building blocks were separated by partially coherent interfaces. The XRD simulation results showed that a specific packing of the primary crystalline blocks in the nanostructured γ-Al2O3 particles with formation of planar defects on {001}, {100}, and {101} planes nicely accounted for pronounced diffuse scattering, anisotropic peak broadening and peak shifts in the experimental XRD pattern. The identified planar defects in cation sublattice seem to be described as filling cation non-spinel sites in existing crystallographic models of γ-Al2O3 structure. The overall findings provided an insight into the complex nanostructure, which is intrinsic to the metastable γ-Al2O3 oxide.

  3. Nanostructured Origami (Trademark) 3D Fabrication and Self Assembly Process for Soldier Combat Systems

    DTIC Science & Technology

    2004-12-01

    the Japanese art of “ origami ”) involves patterning adjacent 2D membranes that can be lifted off (using methods we have developed) of a silicon...innovative process holds immense potential for the Army’s Objective Force Warrior. Nanostructured Origami enables many practical and promising...Nanostructured Origami allows such devices to be formed from a single, micro/nanofabricated layer. In addition, nanoarchitecture can be added

  4. 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.

  5. 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.

  6. 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.

  7. Stretchable array of metal nanodisks on a 3D sinusoidal wavy elastomeric substrate for frequency tunable plasmonics

    NASA Astrophysics Data System (ADS)

    Feng, Di; Zhang, Hui; Xu, Siyi; Tian, Limei; Song, Ningfang

    2017-03-01

    Metal nanostructures integrated with soft, elastomeric substrates provide an unusual platform with capabilities in plasmonic frequency tuning of mechanical strain. In this paper, we have prepared a tunable optical device, dense arrays of plasmonic nanodisks on a low-modulus, and high-elongation elastomeric substrate with a three-dimensional (3D) sinusoidal wavy, and their optical characteristics have been measured and analyzed in detail. Since surface plasmon is located and propagates along metal surfaces with sub-wavelength structures, and those dispersive properties are determined by the coupling strength between the individual structures, in this study, a 3D sinusoidal curve elastomeric substrate is used to mechanically control the inter-nanodisk spacing by applying straining and creating a frequency tunable plasmonic device. Here we study the optical resonance peak shifting generated by stretching this type of flexible device, and the role that 3D sinusoidal curve surface configuration plays in determining the tunable properties. Since only the hybrid dipolar mode has been observed in experiments, the coupled dipole approximation (CDA) method is employed to simulate the optical response of these devices, and the experimental and simulation results show that these devices have high tunability to shift optical resonance peaks at near-infrared wavelengths, which will provide strong potential for new soft optical sensors and wearable plasmonic sensors.

  8. Stretchable array of metal nanodisks on a 3D sinusoidal wavy elastomeric substrate for frequency tunable plasmonics.

    PubMed

    Feng, Di; Zhang, Hui; Xu, Siyi; Tian, Limei; Song, Ningfang

    2017-03-17

    Metal nanostructures integrated with soft, elastomeric substrates provide an unusual platform with capabilities in plasmonic frequency tuning of mechanical strain. In this paper, we have prepared a tunable optical device, dense arrays of plasmonic nanodisks on a low-modulus, and high-elongation elastomeric substrate with a three-dimensional (3D) sinusoidal wavy, and their optical characteristics have been measured and analyzed in detail. Since surface plasmon is located and propagates along metal surfaces with sub-wavelength structures, and those dispersive properties are determined by the coupling strength between the individual structures, in this study, a 3D sinusoidal curve elastomeric substrate is used to mechanically control the inter-nanodisk spacing by applying straining and creating a frequency tunable plasmonic device. Here we study the optical resonance peak shifting generated by stretching this type of flexible device, and the role that 3D sinusoidal curve surface configuration plays in determining the tunable properties. Since only the hybrid dipolar mode has been observed in experiments, the coupled dipole approximation (CDA) method is employed to simulate the optical response of these devices, and the experimental and simulation results show that these devices have high tunability to shift optical resonance peaks at near-infrared wavelengths, which will provide strong potential for new soft optical sensors and wearable plasmonic sensors.

  9. An in-depth spectroscopic examination of molecular bands from 3D hydrodynamical model atmospheres. II. Carbon-enhanced metal-poor 3D model atmospheres

    NASA Astrophysics Data System (ADS)

    Gallagher, A. J.; Caffau, E.; Bonifacio, P.; Ludwig, H.-G.; Steffen, M.; Homeier, D.; Plez, B.

    2017-02-01

    Context. Tighter constraints on metal-poor stars we observe are needed to better understand the chemical processes of the early Universe. Computing a stellar spectrum in 3D allows one to model complex stellar behaviours, which cannot be replicated in 1D. Aims: We examine the effect that the intrinsic CNO abundances have on a 3D model structure and the resulting 3D spectrum synthesis. Methods: Model atmospheres were computed in 3D for three distinct CNO chemical compositions using the CO5BOLD model atmosphere code, and their internal structures were examined. Synthetic spectra were computed from these models using Linfor3D and they were compared. New 3D abundance corrections for the G-band and a selection of UV OH lines were also computed. Results: The varying CNO abundances change the metal content of the 3D models. This had an effect on the model structure and the resulting synthesis. However, it was found that the C/O ratio had a larger effect than the overall metal content of a model. Conclusions: Our results suggest that varying the C/O ratio has a substantial impact on the internal structure of the 3D model, even in the hot turn-off star models explored here. This suggests that bespoke 3D models, for specific CNO abundances should be sought. Such effects are not seen in 1D at these temperature regimes.

  10. Confined Growth of Metal Nanoparticles Within 3D DNA Origami Molds.

    PubMed

    Sun, Wei; Shen, Jie

    2017-01-01

    Manufacturing prescribed shaped metal nanoparticles promises emerging applications in plasmonics, energy, and disease diagnosis. The key to the shape-controllable synthesis is generating local environments encoded with prescribed geometrical information. Here, we describe a general strategy that uses 3D self-assembled DNA origami as mold to confine the casting growth of metal nanoparticle. By transferring the shape information from DNA cavities to metal nanoparticles, metal nanoparticles with prescribed shapes, dimensions, and surface binding features could be rationally designed and synthesized.

  11. Designing 3D interconnected continuous nanoporous Co/CoO core-shell nanostructure electrodes for a high-performance pseudocapacitor

    NASA Astrophysics Data System (ADS)

    Qing, Chen; Zhou, Qin; Qu, Gan; Chen, Xinqi; Wang, Hai; Sun, Daming; Wang, Bixiao; Xu, Lifeng; Tang, Yiwen

    2017-02-01

    A high-performance supercapacitor electrode is designed and fabricated with the 3D interconnected continuous nanoporous Co/CoO core-shell hybrid nanostructure grown on nickel foam. The Co/CoO core-shell hybrid nanostructures are obtained via a hydrothermal method, followed by high-temperature annealing in hydrogen atmosphere, and finally placed in air at 50 °C for 1 h. The Co/CoO core-shell nanostructure assembled by a conductive metal-core and a CoO shell, brings low resistance, high specific capacitance of 5.632 F cm-2 and good capability stability (81.5% capacitance retention after 6000 cycles). An asymmetric supercapacitor device built by the Co/CoO (positive electrode) and activated carbon (negative electrode) can deliver a working voltage of 1.7 V and display a high energy density of 0.002 67 Wh cm-2 at a power density of 0.001 62 W cm-2, which is far superior to that of a supercapacitor at a similar power density.

  12. 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.

  13. 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.

  14. 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

  15. Programmable Bidirectional Folding of Metallic Thin Films for 3D Chiral Optical Antennas.

    PubMed

    Mao, Yifei; Zheng, Yun; Li, Can; Guo, Lin; Pan, Yini; Zhu, Rui; Xu, Jun; Zhang, Weihua; Wu, Wengang

    2017-03-10

    3D structures with characteristic lengths ranging from nanometer to micrometer scale often exhibit extraordinary optical properties, and have been becoming an extensively explored field for building new generation nanophotonic devices. Albeit a few methods have been developed for fabricating 3D optical structures, constructing 3D structures with nanometer accuracy, diversified materials, and perfect morphology is an extremely challenging task. This study presents a general 3D nanofabrication technique, the focused ion beam stress induced deformation process, which allows a programmable and accurate bidirectional folding (-70°-+90°) of various metal and dielectric thin films. Using this method, 3D helical optical antennas with different handedness, improved surface smoothness, and tunable geometries are fabricated, and the strong optical rotation effects of single helical antennas are demonstrated.

  16. 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.

  17. 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.

  18. Spin-polarization energies of 3d impurities in metals and alloys

    NASA Astrophysics Data System (ADS)

    Hoshino, T.; Zeller, R.; Dederichs, P. H.; Asada, T.

    1996-05-01

    The spin-polarization energies (SPEs) of 3d impurities in metals are calculated systematically using the impurity LSD-KKR-Green's function method. We show the importance of magnetism for two kinds of experimental results: (1) the interaction energies of 3d impurities with an In-PAC probe in Ag and Pd; and (2) the effect of environment for Mn spin-flip in NiMn and NiMnFe alloys.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  1. 3D dendritic gold nanostructures: seeded growth of a multi-generation fractal architecture.

    PubMed

    Pan, Ming; Xing, Shuangxi; Sun, Ting; Zhou, Wenwen; Sindoro, Melinda; Teo, Hui Hian; Yan, Qingyu; Chen, Hongyu

    2010-10-14

    In this report, we focus on the synthetic challenges for nanoscale 3D fractal architectures, namely the multi-generation growth with control in both size uniformity and colloidal stability; by directing the simultaneous growth of Au and polyaniline on Au seeds, fractal nanoparticles can be achieved with a topology distinctively different from those of spheres, cubes or rods.

  2. 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.

  3. Diffusion of co-sputtered metals as bonding materials for 3D interconnects during thermal treatments.

    PubMed

    Hsu, S Y; Chen, H Y; Chen, K N

    2012-03-01

    Diffusion behaviors of co-sputtered metals during thermal treatments were investigated, where these co-sputtered metals can be used as bonding materials for 3D Interconnects. In this paper, we report the diffusion behaviors and discuss the diffusion mechanisms of co-sputtered metals before and after annealing. Atom and vacancy volume, vacancy formation energy, and activation energy are proposed to explain the diffusion direction and diffusion rate among different co-sputtered metals. Based on the excellent bonding performance of this method, Cu/metal co-sputtering bonding is considered as a potential candidate for advanced bonding technology.

  4. 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

  5. Highly effective surface-enhanced fluorescence substrates with roughened 3D flowerlike silver nanostructures fabricated in liquid crystalline phase

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Yang, Chengliang; Xiang, Xiangjun; Zhang, Peiguang; Peng, Zenghui; Cao, Zhaoliang; Mu, Quanquan; Xuan, Li

    2017-04-01

    Highly effective surface-enhanced fluorescence substrates with roughened 3D flowerlike silver nanostructures were fabricated by electrodeposition in liquid crystalline template which is simple and controllable. Due to the localized surface plasmon resonance of silver nanostructures, the substrates were used as surface enhanced fluorescence substrates. The morphology and optical properties of the substrates were studied. The fluorescence experiments of the Rhodamine 6G on the substrates for different growth times were carried out and the best enhancement factor of 181 was achieved. Eight substrates with the same growth conditions were used to study the reproducibility of the substrate which shows that the fluctuations are within 9%. This substrate was used in organic distributed feedback lasers and the amplified spontaneous emission of poly(2-methoxy-5-(2‧-ethyl-hexyloxy)-p-phenylenevinylene) was enhanced dramatically which means the reduced threshold and improved slope efficiency. Such easily fabricated flower-like silver nanostructure substrates with strong surface enhanced fluorescence effect and good reproducibility are good candidate for potential applications in optical imaging, biotechnology and material detections.

  6. Glycerol-mediated nanostructure modification leading to improved transparency of porous polymeric scaffolds for high performance 3D cell imaging.

    PubMed

    Zhao, Shan; Shen, Zhiyuan; Wang, Jingyu; Li, Xiaokang; Zeng, Yang; Wang, Bingjie; He, Yonghong; Du, Yanan

    2014-07-14

    Glycerol is among the most commonly used optical clearing agents for tissues clearance largely due to refractive index (RI) matching between glycerol and the submerged tissues. Here we applied glycerol as structure modifier at both macroscopic (as porogen) and nanoscopic (as nanostructure ameliorant) scales to fabricate transparent porous scaffolds made from poly(ethylene glycol) (PEG) as well as other widely used biomaterials (e.g., PLGA, PA, or gelatin), whose nanostructures, in the scale of light wavelength, dominantly improved the optical transmittance of the scaffolds even when immersed in RI mismatched medium (e.g., culture medium or water). We further exploited the clearing mechanisms based on Mie scattering theory, illustrating that conformational changes of polymer chains induced by solvent effects of glycerol enhanced the anisotropy (i.e., directional alignment) of the nanostructures, leading to reduced crystallinity and scattering of the resulted PEG scaffolds. Our findings represent the first and systematic demonstration with both experimental and theoretical evidence in effectively clearing porous polymeric scaffolds by mechanisms other than RI matching, which could tackle the limitations of current optical imaging of cells cultured within three-dimensional (3D) opaque porous scaffolds, such as poor visibility, low spatial resolution, and small penetration depth.

  7. Nanostructured metal sulfides for energy storage

    NASA Astrophysics Data System (ADS)

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-08-01

    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.

  8. Nanostructured metal sulfides for energy storage.

    PubMed

    Rui, Xianhong; Tan, Huiteng; Yan, Qingyu

    2014-09-07

    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.

  9. 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.

  10. Nanolithography. Large-scale nanoshaping of ultrasmooth 3D crystalline metallic structures.

    PubMed

    Gao, Huang; Hu, Yaowu; Xuan, Yi; Li, Ji; Yang, Yingling; Martinez, Ramses V; Li, Chunyu; Luo, Jian; Qi, Minghao; Cheng, Gary J

    2014-12-12

    We report a low-cost, high-throughput benchtop method that enables thin layers of metal to be shaped with nanoscale precision by generating ultrahigh-strain-rate deformations. Laser shock imprinting can create three-dimensional crystalline metallic structures as small as 10 nanometers with ultrasmooth surfaces at ambient conditions. This technique enables the successful fabrications of large-area, uniform nanopatterns with aspect ratios as high as 5 for plasmonic and sensing applications, as well as mechanically strengthened nanostructures and metal-graphene hybrid nanodevices.

  11. 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

  12. 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.

  13. Predicting the electronic properties of 3D, million-atom semiconductor nanostructure architectures

    NASA Astrophysics Data System (ADS)

    Zunger, A.; Franceschetti, A.; Bester, G.; Jones, W. B.; Kim, Kwiseon; Graf, P. A.; Wang, L.-W.; Canning, A.; Marques, O.; Voemel, C.; Dongarra, J.; Langou, J.; Tomov, S.

    2006-09-01

    The past ~10 years have witnessed revolutionary breakthroughs both in synthesis of quantum dots (leading to nearly monodispersed, defect-free nanostructures) and in characterization of such systems, revealing ultra narrow spectroscopic lines of <1 meV width, exposing new intriguing effects, such as multiple exciton generation, fine-structure splitting, quantum entanglement, multiexciton recombination and more. These discoveries have led to new technological applications including quantum computing and ultra-high efficiency solar cells. Our work in this project is based on two realizations/observations: First, that the dots exhibiting clean and rich spectroscopic and transport characteristics are rather big. Indeed, the phenomenology indicated above is exhibited only by the well-passivated defect-free quantum dots containing at least a few thousand atoms (colloidal) and even a few hundred thousand atoms (self assembled). Understanding the behavior of nanotechnology devices requires the study of even larger, million-atom systems composed of multiple components such as wires+dots+films. Second, first-principles many-body computational techniques based on current approaches (Quantum Monte-Carlo, GW, Bethe-Salpeter) are unlikely to be adaptable to such large structures and, at the same time, the effective mass-based techniques are too crude to provide insights on the many-body/atomistic phenomenology revealed by experiment. Thus, we have developed a set of methods that use an atomistic approach (unlike effective-mass based techniques) and utilize single-particle + many body techniques that are readily scalable to ~103-106 atom nanostructures. New mathematical and computational techniques have also been developed to accelerate our calculations and go beyond simple conjugate gradient based methods allowing us to study larger systems. In this short paper based on a poster presented at the DOE SciDAC06 conference we will present the overall structure as well as highlights

  14. 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.

  15. Surface Plasmon Propagation in Nanostructured Metallic Waveguides

    NASA Astrophysics Data System (ADS)

    Calm, Y. M.; Merlo, J. M.; Rose, A. H.; Nesbitt, N. T.; Boyce, A. M.; McMahon, G.; Burns, M. J.; Kempa, K.; Naughton, M. J.

    2015-03-01

    Visible frequencies of light can be routed on subwavelength scales with nanostructured, metallic waveguides by coupling optical energy to surface plasmon (SP) modes at a metal-insulator interface. Epitaxially-grown Ag nanowires and nanocoaxes provide a low-loss, ``model'' system to characterize the propagation of SP waves. We have studied these structures by electron, focused ion, scanning probe, and optical microscopies, and have observed propagation lengths exceeding 15λvac with confinement on the order of 0 . 07(λvac) 2 . Experimental efforts towards lithographically-fabricated metal-insulator-metal waveguides are discussed. Finally, an architecture for a nanocoax-based optical microscope, which extracts near-field (evanescent) information and propagates it into the far-field, is presented. Supported by the W.M. Keck Foundation.

  16. 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

  17. 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

  18. 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.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

    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.

  1. Tuning the electronic and magnetic properties of borophene by 3d transition-metal atom adsorption

    NASA Astrophysics Data System (ADS)

    Li, J. Y.; Lv, H. Y.; Lu, W. J.; Shao, D. F.; Xiao, R. C.; Sun, Y. P.

    2016-12-01

    The electronic and magnetic properties of borophene functionalized by 3d transition metal (TM) atom adsorption are investigated by using first-principles calculations. The results show that the 3d TM atoms can be adsorbed on borophene with high binding energies ranging between 5.9 and 8.3 eV. Interestingly, the originally nonmagnetic borophene tends to be ferromagnetic when Ti, V, Cr, Mn, and Fe atoms are adsorbed, and the magnetic moments are dominated by the TM atoms. The origin of the ferromagnetism is discussed based on the Stoner criterion. Our results indicate that the magnetic properties of borophene can be effectively tuned through the adsorption of 3d TM atoms, which could have promising applications in spintronics and nanoelectronics.

  2. 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.

  3. (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

  4. Periodic table of 3d-metal dimers and their ions.

    PubMed

    Gutsev, G L; Mochena, M D; Jena, P; Bauschlicher, C W; Partridge, H

    2004-10-08

    The ground states of the mixed 3d-metal dimers TiV, TiCr, TiMn, TiFe, TiCo, TiNi, TiCu, TiZn, VCr, VMn, VFe, VCo, VNi, VCu, VZn, CrMn, CrFe, CrCo, CrNi, CrCu, CrZn, MnFe, MnCo, MnNi, MnCu, MnZn, FeCo, FeNi, FeCu, FeZn, CoNi, CoCu, CoZn, NiCu, NiZn, and CuZn along with their singly negatively and positively charged ions are assigned based on the results of computations using density functional theory with generalized gradient approximation for the exchange-correlation functional. Except for TiCo and CrMn, our assignment agrees with experiment. Computed spectroscopic constants (r(e),omega(e),D(o)) are in fair agreement with experiment. The ground-state spin multiplicities of all the ions are found to differ from the spin multiplicities of the corresponding neutral parents by +/-1. Except for TiV, MnFe, and MnCu, the number of unpaired electrons, N, in a neutral ground-state dimer is either N(1)+N(2) or mid R:N(1)-N(2)mid R:, where N(1) and N(2) are the numbers of unpaired 3d electrons in the 3d(n)4s(1) occupation of the constituent atoms. Combining the present and previous results obtained at the same level of theory for homonuclear 3d-metal and ScX (X=Ti-Zn) dimers allows one to construct "periodic" tables of all 3d-metal dimers along with their singly charged ions.

  5. Quasi-3D modeling of surface potential and threshold voltage of Triple Metal Quadruple Gate MOSFETs

    NASA Astrophysics Data System (ADS)

    Gupta, Santosh Kumar; Shah, Mihir Kumar P.

    2017-01-01

    In this paper we present electrostatic model of 3D Triple Metal Quadruple Gate (TMQG) MOSFET of rectangular cross-section based on quasi-3D method. The analytical equations for channel potential and characteristic length have been derived by decomposing TMQG into two 2D perpendicular cross-sections (triple metal double gate, TMDG) and the effective characteristic length of TMQG is found using equivalent number of gates (ENG) method. For each of the TMDG, 2D Poisson's equation is solved by parabolic approximation and proper boundary conditions to calculate channel potential. The threshold voltage expression is developed using inversion carrier charge sheet density method. The developed models for channel potential and threshold voltage are validated using numerical simulations of TMQG. The developed model provides the design guidelines for TMQG with improved HCEs and SCEs.

  6. Design for low-cost gas metal arc weld-based aluminum 3-D printing

    NASA Astrophysics Data System (ADS)

    Haselhuhn, Amberlee S.

    Additive manufacturing, commonly known as 3-D printing, has the potential to change the state of manufacturing across the globe. Parts are made, or printed, layer by layer using only the materials required to form the part, resulting in much less waste than traditional manufacturing methods. Additive manufacturing has been implemented in a wide variety of industries including aerospace, medical, consumer products, and fashion, using metals, ceramics, polymers, composites, and even organic tissues. However, traditional 3-D printing technologies, particularly those used to print metals, can be prohibitively expensive for small enterprises and the average consumer. A low-cost open-source metal 3-D printer has been developed based upon gas metal arc weld (GMAW) technology. Using this technology, substrate release mechanisms have been developed, allowing the user to remove a printed metal part from a metal substrate by hand. The mechanical and microstructural properties of commercially available weld alloys were characterized and used to guide alloy development in 4000 series aluminum-silicon alloys. Wedge casting experiments were performed to screen magnesium, strontium, and titanium boride alloying additions in hypoeutectic aluminum-silicon alloys for their properties and the ease with which they could be printed. Finally, the top performing alloys, which were approximately 11.6% Si modified with strontium and titanium boride were cast, extruded, and drawn into wire. These wires were printed and the mechanical and microstructural properties were compared with those of commercially available alloys. This work resulted in an easier-to-print aluminum-silicon-strontium alloy that exhibited lower porosity, equivalent yield and tensile strengths, yet nearly twice the ductility compared to commercial alloys.

  7. 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.

  8. Metal-polymer composites comprising nanostructures and applications thereof

    DOEpatents

    Wang, Hsing-Lin [Los Alamos, NM; Jeon, Sea Ho [Dracut, MA; Mack, Nathan H [Los Alamos, NM

    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.

  9. Metal-polymer composites comprising nanostructures and applications thereof

    DOEpatents

    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.

  10. 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.

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

    PubMed

    Tiwari, Anand P; Yoo, HeeJoun; Lee, JeongTaik; Kim, Doyoung; Park, Jong Hyeok; Lee, Hyoyoung

    2015-07-28

    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.

  12. 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

    2015-05-28

    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.

  13. 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

  14. 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.

  15. 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.

  16. Detection of inhomogeneities in a metal cylinder using ESPI and 3D pulsed digital holography

    NASA Astrophysics Data System (ADS)

    Saucedo-Anaya, Tonatiuh; Mendoza Santoyo, Fernando; Perez-Lopez, Carlos; de la Torre Ibarra, Manuel

    2004-06-01

    ESPI and 3D pulsed Digital Holography have been applied to detect inhomogeneities inside a metal cylinder. A shaker was employed to produce a mechanical wave that propagates through the inner structure of the cylinder in such a way that it generates vibrational resonant modes on the cylinder surface. An out of plane ESPI optical sensitive configuration was used to detect vibrational resonant modes. A 3D multi-pulse digital holography system was used to obtain quantitative deformation data of the dynamically moving cylinder. The local decrease in structural stiffness inside the cylinder due to an inhomogeneity produces an asymmetry in the resonant mode shape. Results show that the inhomogeneity produces an asymmetry in its vibrational resonant modes. The method may be reliably used to study and compare data from inside homogeneous and inhomogeneous solid materials.

  17. Magnetic engineering in 3d transition metals on phosphorene by strain

    NASA Astrophysics Data System (ADS)

    Cai, Xiaolin; Niu, Chunyao; Wang, Jianjun; Yu, Weiyang; Ren, XiaoYan; Zhu, Zhili

    2017-04-01

    Using first-principles density functional theory (DFT) calculations, we systematically investigate the strain effects on the adsorption energies, magnetic ordering and electronic properties of 3d transition metal (TM) atoms (from Sc to Co) adsorbed on phosphorene (P). We find that the adsorption energy of TM can be enhanced by compressive strain whereas weakened by tensile strain. Our results show that strain plays a decisive role in the magnetic moments as well as the magnetic coupling states of TM adatoms. Importantly, the transitions from antiferromagnetic (AFM) state to ferromagnetic (FM) state or to another different AFM ordering can be induced by strain effect. In addition, we observe the semiconductor to metal or half-metal transitions in some TM@P systems by applying strain. Our findings shed a new light on precisely engineering the magnetic properties and electronic properties of the TM@P systems, which will have great potential applications in spin electronics and other related fields.

  18. 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.

  19. 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.

  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. 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.

  3. Landau damping of surface plasmons in metal nanostructures

    NASA Astrophysics Data System (ADS)

    Shahbazyan, Tigran V.

    2016-12-01

    We develop a quantum-mechanical theory for Landau damping of surface plasmons in metal nanostructures of arbitrary shape. We show that the electron surface scattering, which facilitates plasmon decay in small nanostructures, can be incorporated into the metal dielectric function on par with phonon and impurity scattering. The derived surface scattering rate is determined by the local field polarization relative to the metal-dielectric interface and is highly sensitive to the system geometry. We illustrate our model by providing analytical results for surface scattering rate in some common shape nanostructures. Our results can be used for calculations of hot carrier generation rates in photovoltaics and photochemistry applications.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Strength and scales of itinerant spin fluctuations in 3 d paramagnetic metals

    NASA Astrophysics Data System (ADS)

    Wysocki, Aleksander L.; Kutepov, Andrey; Antropov, Vladimir P.

    2016-10-01

    The full spin density fluctuations (SDF) spectra in 3 d paramagnetic metals are analyzed from first principles using the linear response technique. Using the calculated complete wave vector and energy dependence of the dynamic spin susceptibility, we obtain the most important, but elusive, characteristic of SDF in solids: on-site spin correlator (SC). We demonstrate that the SDF have a mixed character consisting of interacting collective and single-particle excitations of similar strength spreading continuously over the entire Brillouin zone and a wide energy range up to femtosecond time scales. These excitations cannot be adiabatically separated and their intrinsically multiscale nature should always be taken into account for a proper description of metallic systems. Overall, in all studied systems, despite the lack of local moment, we found a very large SC resulting in an effective fluctuating moment of the order of several Bohr magnetons.

  9. Quantum anomalous Hall effect and tunable topological states in 3d transition metals doped silicene.

    PubMed

    Zhang, Xiao-Long; Liu, Lan-Feng; Liu, Wu-Ming

    2013-10-09

    Silicene is an intriguing 2D topological material which is closely analogous to graphene but with stronger spin orbit coupling effect and natural compatibility with current silicon-based electronics industry. Here we demonstrate that silicene decorated with certain 3d transition metals (Vanadium) can sustain a stable quantum anomalous Hall effect using both analytical model and first-principles Wannier interpolation. We also predict the quantum valley Hall effect and electrically tunable topological states could be realized in certain transition metal doped silicene where the energy band inversion occurs. Our findings provide new scheme for the realization of quantum anomalous Hall effect and platform for electrically controllable topological states which are highly desirable for future nanoelectronics and spintronics application.

  10. Strength and scales of itinerant spin fluctuations in 3d paramagnetic metals

    DOE PAGES

    Wysocki, Aleksander L.; Kutepov, Andrey; Antropov, Vladimir P.

    2016-10-10

    The full spin density fluctuations (SDF) spectra in 3d paramagnetic metals are analyzed from first principles using the linear response technique. Using the calculated complete wave vector and energy dependence of the dynamic spin susceptibility, we obtain the most important, but elusive, characteristic of SDF in solids: on-site spin correlator (SC). We demonstrate that the SDF have a mixed character consisting of interacting collective and single-particle excitations of similar strength spreading continuously over the entire Brillouin zone and a wide energy range up to femtosecond time scales. These excitations cannot be adiabatically separated and their intrinsically multiscale nature should alwaysmore » be taken into account for a proper description of metallic systems. Altogether, in all studied systems, despite the lack of local moment, we found a very large SC resulting in an effective fluctuating moment of the order of several Bohr magnetons.« less

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

    DOE PAGES

    Klein, C.; Vollmers, N. J.; Gerstmann, U.; ...

    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

  12. 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.

  13. Positioning of quantum dots on metallic nanostructures.

    PubMed

    Kramer, R K; Pholchai, N; Sorger, V J; Yim, T J; Oulton, R; Zhang, X

    2010-04-09

    The capability to position individual emitters, such as quantum dots, near metallic nanostructures is highly desirable for constructing active optical devices that can manipulate light at the single photon level. The emergence of the field of plasmonics as a means to confine light now introduces a need for high precision and reliability in positioning any source of emission, which has thus far been elusive. Placing an emission source within the influence of plasmonic structures now requires accuracy approaching molecular length scales. In this paper we report the ability to reliably position nanoscale functional objects, specifically quantum dots, with sub-100-nm accuracy, which is several times smaller than the diffraction limit of a quantum dot's emission light. Electron beam lithography-defined masks on metallic surfaces and a series of surface chemical functionalization processes allow the programmed assembly of DNA-linked colloidal quantum dots. The quantum dots are successfully functionalized to areas as small as (100 nm)(2) using the specific binding of thiolated DNA to Au/Ag, and exploiting the streptavidin-biotin interaction. An analysis of the reproducibility of the process for various pattern sizes shows that this technique is potentially scalable to the single quantum dot level with 50 nm accuracy accompanied by a moderate reduction in yield.

  14. 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.

  15. Optical transmission theory for metal-insulator-metal periodic nanostructures

    NASA Astrophysics Data System (ADS)

    Blanchard-Dionne, Andre-Pierre; Meunier, Michel

    2017-01-01

    A semi-analytical formalism for the optical properties of a metal-insulator-metal periodic nanostructure using coupled-mode theory is presented. This structure consists in a dielectric layer in between two metallic layers with periodic one-dimensional nanoslit corrugation. The model is developed using multiple-scattering formalism, which defines transmission and reflection coefficients for each of the interface as a semi-infinite medium. Total transmission is then calculated using a summation of the multiple paths of light inside the structure. This method allows finding an exact solution for the transmission problem in every dimension regime, as long as a sufficient number of diffraction orders and guided modes are considered for the structure. The resonant modes of the structure are found to be related to the metallic slab only and to a combination of both the metallic slab and dielectric layer. This model also allows describing the resonant behavior of the system in the limit of a small dielectric layer, for which discontinuities in the dispersion curves are found. These discontinuities result from the out-of-phase interference of the different diffraction orders of the system, which account for field interaction for both inner interfaces of the structure.

  16. Optical transmission theory for metal-insulator-metal periodic nanostructures

    NASA Astrophysics Data System (ADS)

    Blanchard-Dionne, Andre-Pierre; Meunier, Michel

    2016-11-01

    A semi-analytical formalism for the optical properties of a metal-insulator-metal periodic nanostructure using coupled-mode theory is presented. This structure consists in a dielectric layer in between two metallic layers with periodic one-dimensional nanoslit corrugation. The model is developed using multiple-scattering formalism, which defines transmission and reflection coefficients for each of the interface as a semi-infinite medium. Total transmission is then calculated using a summation of the multiple paths of light inside the structure. This method allows finding an exact solution for the transmission problem in every dimension regime, as long as a sufficient number of diffraction orders and guided modes are considered for the structure. The resonant modes of the structure are found to be related to the metallic slab only and to a combination of both the metallic slab and dielectric layer. This model also allows describing the resonant behavior of the system in the limit of a small dielectric layer, for which discontinuities in the dispersion curves are found. These discontinuities result from the out-of-phase interference of the different diffraction orders of the system, which account for field interaction for both inner interfaces of the structure.

  17. 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

  18. 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.

  19. Metallic glass nanostructures of tunable shape and composition.

    PubMed

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

    2015-04-22

    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.

  20. 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.

  1. Simulation of metal forming processes with a 3D adaptive remeshing procedure

    NASA Astrophysics Data System (ADS)

    Zeramdini, Bessam; Robert, Camille; Germain, Guenael; Pottier, Thomas

    2016-10-01

    In this paper, a fully adaptive 3D numerical methodology based on a tetrahedral element was proposed in order to improve the finite element simulation of any metal forming process. This automatic methodology was implemented in a computational platform which integrates a finite element solver, 3D mesh generation and a field transfer algorithm. The proposed remeshing method was developed in order to solve problems associated with the severe distortion of elements subject to large deformations, to concentrate the elements where the error is large and to coarsen the mesh where the error is small. This leads to a significant reduction in the computation times while maintaining simulation accuracy. In addition, in order to enhance the contact conditions, this method has been coupled with a specific operator to maintain the initial contact between the workpiece nodes and the rigid tool after each remeshing step. In this paper special attention is paid to the data transfer methods and the necessary adaptive remeshing steps are given. Finally, a numerical example is detailed to demonstrate the efficiency of the approach and to compare the results for the different field transfer strategies.

  2. 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.

  3. 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.

  4. Tunable electronic behavior in 3d transition metal doped 2H-WSe2

    NASA Astrophysics Data System (ADS)

    Liu, Shuai; Huang, Songlei; Li, Hongping; Zhang, Quan; Li, Changsheng; Liu, Xiaojuan; Meng, Jian; Tian, Yi

    2017-03-01

    Structural and electronic properties of 3d transition metal Sc, Ti, Cr and Mn incorporated 2H-WSe2 have been systematically investigated by first-principles calculations based on density functional theory. The calculated formation energies reveal that all the doped systems are thermodynamically more favorable under Se-rich condition than W-rich condition. The geometry structures almost hold that of the pristine 2H-WSe2 albeit with slight lattice distortion. More importantly, the electronic properties have been significantly tuned by the dopants, i.e., metal and semimetal behavior has been found in Sc, Ti and Mn-doped 2H-WSe2, respectively, semiconducting nature with narrowed band gap is expected in Cr-doped case, just as that of the pristine 2H-WSe2. In particular, magnetic character is realized by incorporation of Mn impurity with a total magnetic moment of 0.96 μB. Our results suggest chemical doping is an effective way to precisely tailor the electronic structure of layered transition metal dichalcogenide 2H-WSe2 for target technological applications.

  5. Nanocasted synthesis of mesoporous metal oxides and mixed oxides from mesoporous cubic (Ia3d) vinylsilica.

    PubMed

    Wang, Yangang; Wang, Yanqin; Liu, Xiaohui; Guo, Yun; Guo, Yanglong; Lu, Guanzhong; Schüth, Ferdi

    2008-11-01

    Mesoporous metal oxides and mixed oxides, such as NiO, CeO2, Cr2O3, Fe203, Mn2O3, NiFe2O4 and Ce(x)Zr(1-x)O2 (x=0.8 and 0.6) have been synthesized by nanocasting from mesoporous cubic (la3d) vinyl-functionalized silica (vinylsilica). Their structural properties were characterized by XRD, TEM, N2-sorption and Raman spectra. Thus-prepared mesoporous materials possess a high BET surface area (110-190 m2g(-1)), high pore volume (0.25-0.40 cm3g(-1)) and relatively ordered structures. The catalytic properties of Cr2O3 were tested in the oxidation of toluene. The mesoporous Cr2O3 exhibits unusually high catalytic activity in the complete oxidation of toluene as compared with commercial Cr2O3.

  6. Exploring the surface reactivity of 3d metal endofullerenes: a density-functional theory study.

    PubMed

    Estrada-Salas, Rubén E; Valladares, Ariel A

    2009-09-24

    Changes in the preferential sites of electrophilic, nucleophilic, and radical attacks on the pristine C60 surface with endohedral doping using 3d transition metal atoms were studied via two useful reactivity indices, namely the Fukui functions and the molecular electrostatic potential. Both of these were calculated at the density functional BPW91 level of theory with the DNP basis set. Our results clearly show changes in the preferential reactivity sites on the fullerene surface when it is doped with Mn, Fe, Co, or Ni atoms, whereas there are no significant changes in the preferential reactivity sites on the C60 surface upon endohedral doping with Cu and Zn atoms. Electron affinities (EA), ionization potentials (IP), and HOMO-LUMO gaps (Eg) were also calculated to complete the study of the endofullerene's surface reactivity. These findings provide insight into endofullerene functionalization, an important issue in their application.

  7. Multiple-scattering approach to the x-ray-absorption spectra of 3d transition metals

    NASA Astrophysics Data System (ADS)

    Kitamura, Michihide; Muramatsu, Shinji; Sugiura, Chikara

    1986-04-01

    The x-ray-absorption near-edge structure (XANES) has been calculated for the 3d transition metals Cr, Fe, Ni, and Cu from a multiple-scattering approach within the muffin-tin-potential approximation, as a first step to studying the XANES for complicated materials. The muffin-tin potential is constructed via the Mattheiss prescription using the atomic data of Herman and Skillman. It is found that the XANES is sensitive to the potential used and that the calculated XANES spectra reproduce the number of peaks and their separations observed experimentally. The final spectra, including the lifetime-broadening effect, show the general features of each material. We emphasize that the multiple-scattering theory which can be applied to the disordered systems as well as the ordered ones may be promising as a tool to analyze the XANES of complicated materials.

  8. Electronic Properties of COPPER-3d Transition-Metal Pairs in Silicon

    NASA Astrophysics Data System (ADS)

    Justo, João F.; Assali, Lucy V. C.

    We report a theoretical investigation of the chemical trends in the electronic properties of the substitutional Cu-interstitial 3d-transition-metal (Cr, Mn, Fe) trigonal pairs in silicon. The calculations were carried out in the framework of the multiple-scattering Xα molecular cluster model. The electronic structures show that the stability of these pairs is mostly the result of a covalent interaction between the molecular orbitals coming not only from the Cu and TM atoms but also from the neighboring Si atoms. These results are in contrast to an ionic model which has been generally invoked to explain the stability of those pairs, but in agreement with some recent experimental findings. The Fermi contact terms for all the stable pairs in different charge states were computed and compared to available experimental data. We speculate on the existence of a different microscopic structure to explain these Cu-related complex pairs.

  9. 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.

  10. 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.

  11. Structural and property studies on metal-organic compounds with 3-D supramolecular network

    NASA Astrophysics Data System (ADS)

    Zhang, Qi-Ying; Ma, Ke-Fang; Xiao, Hong-Ping; Li, Xin-Hua; Shi, Qian

    2014-07-01

    Two carboxylato-bridged allomeric compounds, {[Cu2(dbsa)2(hmt) (H2O)4]1/2·2H2O}n (1), {[Ni(dbsa)(H2O)2]1/2[Ni(dbsa)(hmt)(H2O)2]1/2·2H2O}n (2) (H2dbsa=meso-2,3-dibromosuccinic acid, hmt=hexamethylenetetramine) have been synthesized and characterized by X-ray structral analyses. The metal ions have two kinds of coordination fashion in one unit, and bridged by carboxylate and hmt ligands along with weak interactions existing in the solid structure, forming a 3-D supramolecular network. Variable-temperature magnetic property studies reveal the existence of antiferromagnetic interactions in 1 and 2 with g=2.2, J1=-3.5 cm-1, J2=-2.8 cm-1 for 1, and g=2.1, J=-3.5 cm-1 for 2.

  12. 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

  13. One-dimensional metal oxide nanostructures for heterogeneous catalysis.

    PubMed

    Zhang, Qian; Wang, Hsin-Yi; Jia, Xinli; Liu, Bin; Yang, Yanhui

    2013-08-21

    Metal oxides are of paramount importance in heterogeneous catalysis as either supports or active phases. Controlled synthesis of one-dimensional (1D) metal oxide nanostructures has received enormous attention in heterogeneous catalysis due to the possibility of tailoring the properties of metal oxides by tuning their shapes, sizes, and compositions. This feature article highlights recent advances in shape controlled synthesis of 1D metal oxide nanostructures and their applications in heterogeneous catalysis, with the aim of introducing new insights into the heterogeneous catalyst design.

  14. 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

  15. Nanostructured Metal Oxides and Sulfides for Lithium-Sulfur Batteries.

    PubMed

    Liu, Xue; Huang, Jia-Qi; Zhang, Qiang; Mai, Liqiang

    2017-02-03

    Lithium-sulfur (Li-S) batteries with high energy density and long cycle life are considered to be one of the most promising next-generation energy-storage systems beyond routine lithium-ion batteries. Various approaches have been proposed to break down technical barriers in Li-S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li-S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li-S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium-metal-anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li-S batteries with nanostructured metal oxides/sulfides are also discussed.

  16. Vibrational density of states and thermodynamics at the nanoscale: the 3D-2D transition in gold nanostructures.

    PubMed

    Carles, R; Benzo, P; Pécassou, B; Bonafos, C

    2016-12-16

    Surface enhanced Raman scattering (SERS) is generally and widely used to enhance the vibrational fingerprint of molecules located at the vicinity of noble metal nanoparticles. In this work, SERS is originally used to enhance the own vibrational density of states (VDOS) of nude and isolated gold nanoparticles. This offers the opportunity of analyzing finite size effects on the lattice dynamics which remains unattainable with conventional techniques based on neutron or x-ray inelastic scattering. By reducing the size down to few nanometers, the role of surface atoms versus volume atoms become dominant, and the "text-book" 3D-2D transition on the dynamical behavior is experimentally emphasized. "Anomalies" that have been predicted by a large panel of simulations at the atomic scale, are really observed, like the enhancement of the VDOS at low frequencies or the occurrence of localized modes at frequencies beyond the cut-off in bulk. Consequences on the thermodynamic properties at the nanoscale, like the reduction of the Debye temperature or the excess of the specific heat, have been evaluated. Finally the high sensitivity of reminiscent bulk-like phonons on the arrangements at the atomic scale is used to access the morphology and internal disorder of the nanoparticles.

  17. Vibrational density of states and thermodynamics at the nanoscale: the 3D-2D transition in gold nanostructures

    NASA Astrophysics Data System (ADS)

    Carles, R.; Benzo, P.; Pécassou, B.; Bonafos, C.

    2016-12-01

    Surface enhanced Raman scattering (SERS) is generally and widely used to enhance the vibrational fingerprint of molecules located at the vicinity of noble metal nanoparticles. In this work, SERS is originally used to enhance the own vibrational density of states (VDOS) of nude and isolated gold nanoparticles. This offers the opportunity of analyzing finite size effects on the lattice dynamics which remains unattainable with conventional techniques based on neutron or x-ray inelastic scattering. By reducing the size down to few nanometers, the role of surface atoms versus volume atoms become dominant, and the “text-book” 3D-2D transition on the dynamical behavior is experimentally emphasized. “Anomalies” that have been predicted by a large panel of simulations at the atomic scale, are really observed, like the enhancement of the VDOS at low frequencies or the occurrence of localized modes at frequencies beyond the cut-off in bulk. Consequences on the thermodynamic properties at the nanoscale, like the reduction of the Debye temperature or the excess of the specific heat, have been evaluated. Finally the high sensitivity of reminiscent bulk-like phonons on the arrangements at the atomic scale is used to access the morphology and internal disorder of the nanoparticles.

  18. Vibrational density of states and thermodynamics at the nanoscale: the 3D-2D transition in gold nanostructures

    PubMed Central

    Carles, R.; Benzo, P.; Pécassou, B.; Bonafos, C.

    2016-01-01

    Surface enhanced Raman scattering (SERS) is generally and widely used to enhance the vibrational fingerprint of molecules located at the vicinity of noble metal nanoparticles. In this work, SERS is originally used to enhance the own vibrational density of states (VDOS) of nude and isolated gold nanoparticles. This offers the opportunity of analyzing finite size effects on the lattice dynamics which remains unattainable with conventional techniques based on neutron or x-ray inelastic scattering. By reducing the size down to few nanometers, the role of surface atoms versus volume atoms become dominant, and the “text-book” 3D-2D transition on the dynamical behavior is experimentally emphasized. “Anomalies” that have been predicted by a large panel of simulations at the atomic scale, are really observed, like the enhancement of the VDOS at low frequencies or the occurrence of localized modes at frequencies beyond the cut-off in bulk. Consequences on the thermodynamic properties at the nanoscale, like the reduction of the Debye temperature or the excess of the specific heat, have been evaluated. Finally the high sensitivity of reminiscent bulk-like phonons on the arrangements at the atomic scale is used to access the morphology and internal disorder of the nanoparticles. PMID:27982080

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  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. Assessing the performance of density functional theory for the electronic structure of metal-salens: the 3d(0)-metals.

    PubMed

    Sears, John S; Sherrill, C David

    2008-04-17

    A series of metal-salen complexes of the 3d(0) metals Sc(III), Ti(IV), V(V), Cr(VI), and Mn(VII) have been explored using high-level electronic structure methods including coupled-cluster theory with singles, doubles, and perturbative triples as well as complete active-space third-order perturbation theory. The performance of three common density functional theory approaches has been assessed for both the geometries and the relative energies of the low-lying electronic states. The nondynamical correlation effects are demonstrated to be extremely large in all of the systems examined. Although density functional theory provides reasonable results for some of the systems, the overall agreement is quite poor. This said, the density functional theory approaches are shown to outperform the single-reference perturbation theory and coupled-cluster theory approaches for cases of strong nondynamical correlation.

  6. The emerging multiple metal nanostructures for enhancing the light trapping of thin film organic photovoltaic cells.

    PubMed

    Choy, Wallace C H

    2014-10-18

    Recently, various metal nanostructures have been introduced into organic solar cells (OSCs) for performance enhancement. Here, we review the recent progress in OSCs incorporated with multiple metal nanostructures including various metal nanopatterns and metal nanomaterials. Multiple physical effects arise from these incorporated nanostructures, which require careful distinction. Changes induced by the metal nanostructures are examined in detail from the optical and electrical aspects. With the comprehensive understanding of the physical mechanisms for various metal nanostructures, further improvement in device performance and emerging applications can be expected for the new class of nanostructure-incorporated OSCs.

  7. High-throughput drawing and testing of metallic glass nanostructures.

    PubMed

    Hasan, Molla; Kumar, Golden

    2017-03-02

    Thermoplastic embossing of metallic glasses promises direct imprinting of metal nanostructures using templates. However, embossing high-aspect-ratio nanostructures faces unworkable flow resistance due to friction and non-wetting conditions at the template interface. Herein, we show that these inherent challenges of embossing can be reversed by thermoplastic drawing using templates. The flow resistance not only remains independent of wetting but also decreases with increasing feature aspect-ratio. Arrays of assembled nanotips, nanowires, and nanotubes with aspect-ratios exceeding 1000 can be produced through controlled elongation and fracture of metallic glass structures. In contrast to embossing, the drawing approach generates two sets of nanostructures upon final fracture; one set remains anchored to the metallic glass substrate while the second set is assembled on the template. This method can be readily adapted for high-throughput fabrication and testing of nanoscale tensile specimens, enabling rapid screening of size-effects in mechanical behavior.

  8. Metal nanostructures for non-enzymatic glucose sensing.

    PubMed

    Tee, Si Yin; Teng, Choon Peng; Ye, Enyi

    2017-01-01

    This review covers the recent development of metal nanostructures in electrochemical non-enzymatic glucose sensing. It highlights a variety of nanostructured materials including noble metals, other transition metals, bimetallic systems, and their hybrid with carbon-based nanomaterials. Particularly, attention is devoted to numerous approaches that have been implemented for improving the sensors performance by tailoring size, shape, composition, effective surface area, adsorption capability and electron-transfer properties. The correlation of the metal nanostructures to the glucose sensing performance is addressed with respect to the linear concentration range, sensitivity and detection limit. In overall, this review provides important clues from the recent scientific achievements of glucose sensor nanomaterials which will be essentially useful in designing better and more effective electrocatalysts for future electrochemical sensing industry.

  9. Towards design rules for covalent nanostructures on metal surfaces.

    PubMed

    Björk, Jonas; Hanke, Felix

    2014-01-20

    The covalent molecular assembly on metal surfaces is explored, outlining the different types of applicable reactions. Density functional calculations for on-surface reactions are shown to yield valuable insights into specific reaction mechanisms and trends across the periodic table. Finally, it is shown how design rules could be derived for nanostructures on metal surfaces.

  10. 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.

  11. Fast Surface Dynamics of Metallic Glass Enable Superlatticelike Nanostructure Growth

    NASA Astrophysics Data System (ADS)

    Chen, L.; Cao, C. R.; Shi, J. A.; Lu, Z.; Sun, Y. T.; Luo, P.; Gu, L.; Bai, H. Y.; Pan, M. X.; Wang, W. H.

    2017-01-01

    Contrary to the formation of complicated polycrystals induced by general crystallization, a modulated superlatticelike nanostructure, which grows layer by layer from the surface to the interior of a Pd40Ni10Cu30P20 metallic glass, is observed via isothermal annealing below the glass transition temperature. The generation of the modulated nanostructure can be solely controlled by the annealing temperature, and it can be understood based on the fast dynamic and liquidlike behavior of the glass surface. The observations have implications for understanding the glassy surface dynamics and pave a way for the controllable fabrication of a unique and sophisticated nanostructure on a glass surface to realize the properties' modification.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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}|.

  18. Advanced Micro/Nanostructures for Lithium Metal Anodes

    PubMed Central

    Zhang, Rui; Li, Nian‐Wu; Cheng, Xin‐Bing; Yin, Ya‐Xia

    2017-01-01

    Owning to their very high theoretical capacity, lithium metal anodes are expected to fuel the extensive practical applications in portable electronics and electric vehicles. However, unstable solid electrolyte interphase and lithium dendrite growth during lithium plating/stripping induce poor safety, low Coulombic efficiency, and short span life of lithium metal batteries. Lately, varies of micro/nanostructured lithium metal anodes are proposed to address these issues in lithium metal batteries. With the unique surface, pore, and connecting structures of different nanomaterials, lithium plating/stripping processes have been regulated. Thus the electrochemical properties and lithium morphologies have been significantly improved. These micro/nanostructured lithium metal anodes shed new light on the future applications for lithium metal batteries. PMID:28331792

  19. Advanced Micro/Nanostructures for Lithium Metal Anodes.

    PubMed

    Zhang, Rui; Li, Nian-Wu; Cheng, Xin-Bing; Yin, Ya-Xia; Zhang, Qiang; Guo, Yu-Guo

    2017-03-01

    Owning to their very high theoretical capacity, lithium metal anodes are expected to fuel the extensive practical applications in portable electronics and electric vehicles. However, unstable solid electrolyte interphase and lithium dendrite growth during lithium plating/stripping induce poor safety, low Coulombic efficiency, and short span life of lithium metal batteries. Lately, varies of micro/nanostructured lithium metal anodes are proposed to address these issues in lithium metal batteries. With the unique surface, pore, and connecting structures of different nanomaterials, lithium plating/stripping processes have been regulated. Thus the electrochemical properties and lithium morphologies have been significantly improved. These micro/nanostructured lithium metal anodes shed new light on the future applications for lithium metal batteries.

  20. 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

  1. 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.

  2. 3D assembly of semiconductor and metal nanocrystals: hybrid CdTe/Au structures with controlled content.

    PubMed

    Lesnyak, Vladimir; Wolf, André; Dubavik, Aliaksei; Borchardt, Lars; Voitekhovich, Sergei V; Gaponik, Nikolai; Kaskel, Stefan; Eychmüller, Alexander

    2011-08-31

    A 3D metal ion assisted assembly of nanoparticles has been developed. The approach relies on the efficient complexation of cadmium ions and 5-mercaptomethyltetrazole employed as the stabilizer of both colloidal CdTe and Au nanoparticles. It enables in a facile way the formation of hybrid metal-semiconductor 3D structures with controllable and tunable composition in aqueous media. By means of critical point drying, these assemblies form highly porous aerogels. The hybrid architectures obtained are characterized by electron microscopy, nitrogen adsorption, and optical spectroscopy methods.

  3. Influence of 3 d metal atoms on the geometry, electronic structure, and stability of a Mg13H26 cluster

    NASA Astrophysics Data System (ADS)

    Shelyapina, M. G.; Siretskiy, M. Yu.

    2010-09-01

    This paper reports on the results of the theoretical investigation of magnesium hydride nanoclusters doped with 3 d metals (from Sc to Zn). The influence of transition metal atoms on the geometry, electronic structure, and energy characteristics of the clusters has been analyzed. The results of the performed calculations have been compared with the available experimental data. This comparison has made it possible to predict which 3 d transition elements can serve as the most effective catalysts for the improvement of the thermodynamic characteristics of MgH2.

  4. Noble-metal nanostructures on carburized W(110)

    NASA Astrophysics Data System (ADS)

    Bachmann, Magdalena; Memmel, Norbert; Bertel, Erminald

    2011-07-01

    Noble metal nanostructures of Au, Ag and Cu were prepared on two types of carbon-modified W(110) surfaces-R(15 × 12) and R(15 × 3)-and investigated by means of scanning tunneling microscopy. For all deposited metals qualitatively the same behaviour is observed: On the R(15 × 12)-template always isotropic clusters are formed. In contrast, on the R(15 × 3)-substrate the anisotropy of the nanostructures can be tuned from clusters at low temperatures via thin nanowires to thicker nanobars at high deposition temperatures. At intermediate temperatures on the R(15 × 3) the anisotropic Au nanowires arrange themselves into straight lines along domain boundaries induced by deposition of the Au metal. Similarities and differences to Au nanostructures as recently reported by Varykhalov et al. [A. Varykhalov, O. Rader, W. Gudat. Physical Review B 77, 035412 (2008).] are discussed.

  5. 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.

  6. Electrically conductive gold- and copper-metallized DNA origami nanostructures.

    PubMed

    Geng, Yanli; Pearson, Anthony C; Gates, Elisabeth P; Uprety, Bibek; Davis, Robert C; Harb, John N; Woolley, Adam T

    2013-03-12

    This work demonstrates the use of a circuit-like DNA origami structure as a template to fabricate conductive gold and copper nanostructures on Si surfaces. We improved over previous results by using multiple Pd seeding steps to increase seed uniformity and density. Our process has also been characterized through atomic force microscopy, particle size distribution analysis, and scanning electron microscopy. We found that four successive Pd seeding steps yielded the best results for electroless metal plating on DNA origami. Electrical resistance measurements were done on both Au- and Cu-metallized nanostructures, with each showing ohmic behavior. Gold-plated DNA origami structures made under optimal conditions had an average resistivity of 7.0 × 10(-5) Ω·m, whereas copper-metallized structures had a resistivity as low as 3.6 × 10(-4) Ω·m. Importantly, this is the first demonstration of electrically conductive Cu nanostructures fabricated on either DNA or DNA origami templates. Although resistivities for both gold and copper samples were larger than those of the bulk metal, these metal nanostructures have the potential for use in electrically connecting small structures. In addition, these metallized objects might find use in surface-enhanced Raman scattering experiments.

  7. Dynamic stress-strain states for metal foams using a 3D cellular model

    NASA Astrophysics Data System (ADS)

    Zheng, Zhijun; Wang, Changfeng; Yu, Jilin; Reid, Stephen R.; Harrigan, John J.

    2014-12-01

    Dynamic uniaxial impact behaviour of metal foams using a 3D cell-based finite element model is examined. At sufficiently high loading rates, these materials respond by forming ‘shock or consolidation waves' (Tan et al., 2005a, 2005b). However, the existing dynamic experimental methods have limitations in fully informing this behaviour, particularly for solving boundary/initial value problems. Recently, the problem of the shock-like response of an open-cell foam has been examined by Barnes et al. (2014) using the Hugoniot-curve representations. The present study is somewhat complementary to that approach and additionally aims to provide insight into the ‘rate sensitivity' mechanism applicable to cellular materials. To assist our understanding of the ‘loading rate sensitivity' behaviour of cellular materials, a virtual ‘test' method based on the direct impact technique is explored. Following a continuum representation of the response, the strain field calculation method is employed to determine the local strains ahead of and behind the resulting ‘shock front'. The dynamic stress-strain states in the densification stage are found to be different from the quasi-static ones. It is evident that the constitutive behaviour of the cellular material is deformation-mode dependent. The nature of the ‘rate sensitivity' revealed for cellular materials in this paper is different from the strain-rate sensitivity of dense metals. It is shown that the dynamic stress-strain states behind a shock front of the cellular material lie on a unique curve and each point on the curve corresponds to a particular ‘impact velocity', referred as the velocity upstream of the shock in this study. The dynamic stress-strain curve is related to a layer-wise collapse mode, whilst the equivalent quasi-static curve is related to a random shear band collapse mode. The findings herein are aimed at improving the experimental test techniques used to characterise the rate-sensitivity behaviour

  8. 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.

  9. 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.

  10. Potential energy curves and electronic structure of 3d transition metal hydrides and their cations.

    PubMed

    Goel, Satyender; Masunov, Artëm E

    2008-12-07

    We investigate gas-phase neutral and cationic hydrides formed by 3d transition metals from Sc to Cu with density functional theory (DFT) methods. The performance of two exchange-correlation functionals, Boese-Martin for kinetics (BMK) and Tao-Perdew-Staroverov-Scuseria (TPSS), in predicting bond lengths and energetics, electronic structures, dipole moments, and ionization potentials is evaluated in comparison with available experimental data. To ensure a unique self-consistent field (SCF) solution, we use stability analysis, Fermi smearing, and continuity analysis of the potential energy curves. Broken-symmetry approach was adapted in order to get the qualitatively correct description of the bond dissociation. We found that on average BMK predicted values of dissociation energies and ionization potentials are closer to experiment than those obtained with high level wave function theory methods. This agreement deteriorates quickly when the fraction of the Hartree-Fock exchange in DFT functional is decreased. Natural bond orbital (NBO) population analysis was used to describe the details of chemical bonding in the systems studied. The multireference character in the wave function description of the hydrides is reproduced in broken-symmetry DFT description, as evidenced by NBO analysis. We also propose a new scheme to correct for spin contamination arising in broken-symmetry DFT approach. Unlike conventional schemes, our spin correction is introduced for each spin-polarized electron pair individually and therefore is expected to yield more accurate energy values. We derive an expression to extract the energy of the pure singlet state from the energy of the broken-symmetry DFT description of the low spin state and the energies of the high spin states (pentuplet and two spin-contaminated triplets in the case of two spin-polarized electron pairs). The high spin states are build with canonical natural orbitals and do not require SCF convergence.

  11. Nanofabrication of Metallic Nanostructures and Integration with Light Detection Devices

    NASA Astrophysics Data System (ADS)

    Huang, Liang

    Metallic nanostructures have been investigated with various applications especially for integration with light detection devices. The incident light can be manipulated by those nanostructures to enhance light absorption therefor improve device performance. However, previous studies focused on optical design. The electrical properties of these integrated light detection devices have not been fully considered. The photon generated carriers transport and collection are critical for light detection devices as well. An optimized device platform considering from both the optical and electrical aspects to fully utilize these nanostructures is highly desired for future light detection devices. This dissertation targeted on three objectives, beginning with the fabrication process development of various nanostructures on different substrates. High quality nanostructures were achieved with minimum 20nm gap and 45nm line width. The second objective was developing the metallic fishnet nanostructures integrated Schottky contact a-Si solar cell to improve both light absorption and photon generated carrier collection. The fishnet was designed as the light trapping structure and 2D connected top contact to collect carriers. The third objective was developing metallic nanostructures integrated GeSn photodetectors. The H shape nano antennas were integrated on GeSn photodetectors. Multiple resonant absorption peaks at infrared range were observed using spectroscopic ellipsometry. However, there was no obvious photoresponse value improvement of developed solar cells and H shape antennas integrated GeSn photodetectors. For further investigation, interdigitated electrodes integrated GeSn photodetectors were designed. With less carrier transit time, the responsivity value of the integrated Ge0.991Sn0.009 photodetector was 72muA/W at 1.55mum at room temperature which was 6 times higher comparing to device without integration. Meanwhile, with the increased carrier life time by decreasing

  12. The Effect of Scattering on the Temperature Stratification of 3D Model Atmospheres of Metal-Poor Red Giants

    NASA Astrophysics Data System (ADS)

    Collet, Remo; Hayek, Wolfgang; Asplund, Martin

    2011-08-01

    We study the effects of different approximations of scattering in 3D radiation-hydrodynamics simulations on the photospheric temperature stratification of metal-poor red giant stars. We find that assuming a Planckian source function and neglecting the contribution of scattering to extinction in optically thin layers provides a good approximation of the effects of coherent scattering on the photospheric temperature balance.

  13. 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

  14. 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.

  15. 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.

  16. 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

    2015-07-07

    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.

  17. Ammonia sensors based on metal oxide nanostructures

    NASA Astrophysics Data System (ADS)

    Sekhar Rout, Chandra; Hegde, Manu; Govindaraj, A.; Rao, C. N. R.

    2007-05-01

    Ammonia sensing characteristics of nanoparticles as well as nanorods of ZnO, In2O3 and SnO2 have been investigated over a wide range of concentrations (1 800 ppm) and temperatures (100 300 °C). The best values of sensitivity are found with ZnO nanoparticles and SnO2 nanostructures. Considering all the characteristics, the SnO2 nanostructures appear to be good candidates for sensing ammonia, with sensitivities of 222 and 19 at 300 °C and 100 °C respectively for 800 ppm of NH3. The recovery and response times are respectively in the ranges 12 68 s and 22 120 s. The effect of humidity on the performance of the sensors is not marked up to 60% at 300 °C. With the oxide sensors reported here no interference for NH3 is found from H2, CO, nitrogen oxides, H2S and SO2.

  18. Effect of 3D physiological loading and motion on elastohydrodynamic lubrication of metal-on-metal total hip replacements.

    PubMed

    Gao, Leiming; Wang, Fengcai; Yang, Peiran; Jin, Zhongmin

    2009-07-01

    An elastohydrodynamic lubrication (EHL) simulation of a metal-on-metal (MOM) total hip implant was presented, considering both steady state and transient physiological loading and motion gait cycle in all three directions. The governing equations were solved numerically by the multi-grid method and fast Fourier transform in spherical coordinates, and full numerical solutions were presented included the pressure and film thickness distribution. Despite small variations in the magnitude of 3D resultant load, the horizontal anterior-posterior (AP) and medial-lateral (ML) load components were found to translate the contact area substantially in the corresponding direction and consequently to result in significant squeeze-film actions. For a cup positioned anatomically at 45 degrees , the variation of the resultant load was shown unlikely to cause the edge contact. The contact area was found within the cup dimensions of 70-130 degrees and 90-150 degrees in the AP and ML direction respectively even under the largest translations. Under walking conditions, the horizontal load components had a significant impact on the lubrication film due to the squeeze-film effect. The time-dependent film thickness was increased by the horizontal translation and decreased during the reverse of this translation caused by the multi-direction of the AP load during walking. The minimum film thickness of 12-20 nm was found at 0.4s and around the location at (95, 125) degrees. During the whole walking cycle both the average and centre film thickness were found obviously increased to a range of 40-65 nm, compared with the range of 25-55 nm under one load (vertical) and one motion (flexion-extension) condition, which suggested the lubrication in the current MOM hip implant was improved under 3D physiological loading and motion. This study suggested the lubrication performance especially the film thickness distribution should vary greatly under different operating conditions and the time and

  19. Theoretical study of the adsorption of 3d- and 4d-metals on a WC(0001) surface

    SciTech Connect

    Bakulin, A. V.; Kulkova, S. E.

    2013-08-15

    The interaction of 3d- and 4d-metals with a WC(0001) surface has been studied theoretically by density-functional theory methods depending on surface termination and adsorbate position. The most stable sites of metal adsorption on the surface have been determined. The binding energy of d-metals with the surface is shown to be higher in the case of carbon terminated surface. This is explained by the predominant ionic-covalent contribution to the chemical bond at the interface, with the bond ionicity being determined by charge transfer from the metals to the electronegative carbon. Analysis of the electronic and structural characteristics has revealed the factors affecting the bonding energetics at the metal-carbide interface depending on the metal d-shell filling with electrons.

  20. Efficient Electrochemical and Photoelectrochemical Water Splitting by a 3D Nanostructured Carbon Supported on Flexible Exfoliated Graphene Foil.

    PubMed

    Hou, Yang; Qiu, Ming; Zhang, Tao; Ma, Ji; Liu, Shaohua; Zhuang, Xiaodong; Yuan, Chris; Feng, Xinliang

    2017-01-01

    A novel 3D Co-Nx |P-complex-doped carbon grown on flexible exfoliated graphene foil is designed and constructed for both electrochemical and photoelectrochemical water splitting. The coordination of Co-Nx active centers hybridized with that of neighboring P atoms enhances the electron transfer and optimizes the charge distribution of the carbon surface, which synergistically promotes reaction kinetics by providing more exposed active sites.

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

    PubMed

    Sakhavand, Navid; Shahsavari, Rouzbeh

    2014-10-02

    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.

  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. 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

  4. 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.

  5. Synthesis of branched metal nanostructures with controlled architecture and composition

    NASA Astrophysics Data System (ADS)

    Ortiz, Nancy

    On account of their small size, metal nanoparticles are proven to be outstanding catalysts for numerous chemical transformations and represent promising platforms for applications in the fields of electronics, chemical sensing, medicine, and beyond. Many properties of metal nanoparticles are size-dependent and can be further manipulated through their shape and architecture (e.g., spherical vs. branched). Achieving morphology control of nanoparticles through solution-based techniques has proven challenging due to limited knowledge of morphology development in nanosyntheses. To overcome these complications, a systematic examination of the local ligand environment of metal precursors on nanostructure formation was undertaken to evaluate its contribution to nanoparticle nucleation rate and subsequent growth processes. Specifically, this thesis will provide evidence from ex situ studies---Transmission Electron Microscopy (TEM) and UV-visible spectroscopy (UV-Vis)---that support the hypothesis that strongly coordinated ligands delay burst-like nucleation to generate spherical metal nanoparticles and ligands with intermediate binding affinity regulate the gradual reduction of metal precursors to promote aggregated assembly of nanodendrites. These ex situ studies were coupled with a new in situ perspective, providing detailed understanding of metal precursor transformation, its direct relation to nanoparticle morphology development, and the ligand influence towards the formation of structurally complex metal nanostructures, using in situ synchrotron X-ray Diffraction (XRD) and Ultra Small-Angle X-ray Scattering (USAXS). The principles extracted from the study of monometallic nanostructure formation were also found to be generally applicable to the synthesis of bimetallic nanostructures, e.g., Pd-Pt architectures, with either core-shell or alloyed structures that were readily achieved by ligand selection. These outcomes provide a direct connection between fundamental

  6. 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

  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. Hardening by annealing and softening by deformation in nanostructured metals.

    PubMed

    Huang, Xiaoxu; Hansen, Niels; Tsuji, Nobuhiro

    2006-04-14

    We observe that a nanostructured metal can be hardened by annealing and softened when subsequently deformed, which is in contrast to the typical behavior of a metal. Microstructural investigation points to an effect of the structural scale on fundamental mechanisms of dislocation-dislocation and dislocation-interface reactions, such that heat treatment reduces the generation and interaction of dislocations, leading to an increase in strength and a reduction in ductility. A subsequent deformation step may restore the dislocation structure and facilitate the yielding process when the metal is stressed. As a consequence, the strength decreases and the ductility increases. These observations suggest that for materials such as the nanostructured aluminum studied here, deformation should be used as an optimizing procedure instead of annealing.

  9. 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.

  10. T4 virus-based toolkit for the direct synthesis and 3D organization of metal quantum particles.

    PubMed

    Hou, Li; Gao, Faming; Li, Na

    2010-12-27

    One of the challenges in building superstructures based on small metal particles is producing stable interparticle separation. Herein, we present a novel assembly method based on the use of the T4 bacteriophage capsid as a scaffold for the construction of 3D monodisperse metal-particle arrays. The highly regular and symmetrical protein surface of the T4 capsid allows the site-directed adsorption and subsequent reduction of metal ions, thus permitting the growth of metal particles in situ to enable them to exist at a quantum size with a high degree of monodispersity. Both these characteristics contribute to a great improvement in the electrocatalytic activity of the patterned noble-metal particles. Organized magnetic particles as small as 2-4 nm still maintain an observable ferromagnetic behavior, which makes them promising for a variety of possible biomedical applications.

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

    SciTech Connect

    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.

  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. Atomic-layer alignment tuning for giant perpendicular magnetocrystalline anisotropy of 3d transition-metal thin films.

    PubMed

    Hotta, K; Nakamura, K; Akiyama, T; Ito, T; Oguchi, T; Freeman, A J

    2013-06-28

    The magnetocrystalline anisotropy (MA) of Fe-based transition-metal thin films, consisting of only magnetic 3d elements, was systematically investigated from full-potential linearized augmented plane-wave calculations. The results predict that giant MA with a perpendicular magnetic easy axis (PMA) can be achieved by tuning the atomic-layer alignments in an Fe-Ni thin film. This giant PMA arises from the spin-orbit coupling interaction between occupied and unoccupied Ni dx2-y2,xy bands crossing the Fermi level. A promising 3d transition-metal thin film for the MgO-based magnetic tunnel junctions with the giant PMA was, thus, demonstrated.

  14. Magnetic properties of Pd atomic chains formed during submonolayer deposition of 3d metals on Pd(110)

    NASA Astrophysics Data System (ADS)

    Stepanyuk, O. V.; Ignatiev, P. A.; Negulyaev, N. N.; Saletsky, A. M.; Hergert, W.

    2012-06-01

    Recently, an unusual intermixing-driven scenario for the growth of atomic Pd chains on a Pd(110) surface during deposition of 3d metal atoms has been predicted (Stepanyuk 2009 Phys. Rev. B 79 155410) and confirmed by STM and STS experiments (Wie et al 2009 Phys. Rev. Lett. 103 225504). Performing ab initio calculations we demonstrate that Pd atomic chains grown above embedded Fe atoms exhibit magnetic properties which depend on the substrate mediated exchange interaction between the Fe atoms.

  15. Magnetic properties of Pd atomic chains formed during submonolayer deposition of 3d metals on Pd(110).

    PubMed

    Stepanyuk, O V; Ignatiev, P A; Negulyaev, N N; Saletsky, A M; Hergert, W

    2012-06-13

    Recently, an unusual intermixing-driven scenario for the growth of atomic Pd chains on a Pd(110) surface during deposition of 3d metal atoms has been predicted (Stepanyuk 2009 Phys. Rev. B 79 155410) and confirmed by STM and STS experiments (Wie et al 2009 Phys. Rev. Lett. 103 225504). Performing ab initio calculations we demonstrate that Pd atomic chains grown above embedded Fe atoms exhibit magnetic properties which depend on the substrate mediated exchange interaction between the Fe atoms.

  16. 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

  17. 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

    2016-06-27

    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.

  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. 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

  20. Stroboscobic near-field scanning optical microscopy for 3D mapping of mode profiles of plasmonic nanostructures (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dana, Aykutlu; Ozgur, Erol; Torunoglu, Gamze

    2016-09-01

    We present a dynamic approach to scanning near field optical microscopy that extends the measurement technique to the third dimension, by strobing the illumination in sync with the cantilever oscillation. Nitrogen vacancy (NV) centers in nanodiamonds placed on cantilever tips are used as stable emitters for emission enhancement. Local field enhancement and modulation of optical density states are mapped in three dimensions based on fluorescence intensity and spectrum changes as the tip is scanned over plasmonic nanostructures. The excitation of NV centers is done using a total internal reflection setup. Using a digital phase locked loop to pulse the excitation in various tip sample separations, 2D slices of fluorescence enhancement can be recorded. Alternatively, a conventional SNOM tip can be used to selectively couple wideband excitation to the collection path, with subdiffraction resolution of 60 nm in x and y and 10 nm in z directions. The approach solves the problem of tip-sample separation stabilization over extended periods of measurement time, required to collect data resolved in emission wavelength and three spatial dimensions. The method can provide a unique way of accessing the three dimensional field and mode profiles of nanophotonics structures.

  1. Sensitivity of Neural Stem Cell Survival, Differentiation and Neurite Outgrowth within 3D Hydrogels to Environmental Heavy Metals

    PubMed Central

    Tasneem, Sameera; Farrell, Kurt; Lee, Moo-Yeal; Kothapalli, Chandrasekhar R.

    2015-01-01

    We investigated the sensitivity of embryonic murine neural stem cells exposed to 10 pM – 10 μM concentrations of three heavy metals (Cd, Hg, Pb), continuously for 14 days within 3D collagen hydrogels. Critical endpoints for neurogenesis such as survival, differentiation and neurite outgrowth were assessed. Results suggest significant compromise in cell viability within the first four days at concentrations ≥ 10 nM, while lower concentrations induced a more delayed effect. Mercury and lead suppressed neural differentiation at as low as 10 pM concentration within 7 days, while all three metals inhibited neural and glial differentiation by day 14. Neurite outgrowth remained unaffected at lower cadmium or mercury concentrations (≤ 100 pM), but was completely repressed beyond day 1 at higher concentrations. Higher metal concentrations (≥ 100 pM) suppressed NSC differentiation to motor or dopaminergic neurons. Cytokines and chemokines released by NSCs, and the sub-cellular mechanisms by which metals induce damage to NSCs have been quantified and correlated to phenotypic data. The observed degree of toxicity in NSC cultures is in the order: lead > mercury > cadmium. Results point to the use of biomimetic 3D culture models to screen the toxic effects of heavy metals during developmental stages, and investigate their underlying mechanistic pathways. PMID:26621541

  2. Sensitivity of neural stem cell survival, differentiation and neurite outgrowth within 3D hydrogels to environmental heavy metals.

    PubMed

    Tasneem, Sameera; Farrell, Kurt; Lee, Moo-Yeal; Kothapalli, Chandrasekhar R

    2016-02-03

    We investigated the sensitivity of embryonic murine neural stem cells exposed to 10 pM-10 μM concentrations of three heavy metals (Cd, Hg, Pb), continuously for 14 days within 3D collagen hydrogels. Critical endpoints for neurogenesis such as survival, differentiation and neurite outgrowth were assessed. Results suggest significant compromise in cell viability within the first four days at concentrations ≥10 nM, while lower concentrations induced a more delayed effect. Mercury and lead suppressed neural differentiation at as low as 10 pM concentration within 7 days, while all three metals inhibited neural and glial differentiation by day 14. Neurite outgrowth remained unaffected at lower cadmium or mercury concentrations (≤100 pM), but was completely repressed beyond day 1 at higher concentrations. Higher metal concentrations (≥100 pM) suppressed NSC differentiation to motor or dopaminergic neurons. Cytokines and chemokines released by NSCs, and the sub-cellular mechanisms by which metals induce damage to NSCs have been quantified and correlated to phenotypic data. The observed degree of toxicity in NSC cultures is in the order: lead>mercury>cadmium. Results point to the use of biomimetic 3D culture models to screen the toxic effects of heavy metals during developmental stages, and investigate their underlying mechanistic pathways.

  3. 3D transient model to predict temperature and ablated areas during laser processing of metallic surfaces

    NASA Astrophysics Data System (ADS)

    Naghshine, Babak. B.; Kiani, Amirkianoosh

    2017-02-01

    Laser processing is one of the most popular small-scale patterning methods and has many applications in semiconductor device fabrication and biomedical engineering. Numerical modelling of this process can be used for better understanding of the process, optimization, and predicting the quality of the final product. An accurate 3D model is presented here for short laser pulses that can predict the ablation depth and temperature distribution on any section of the material in a minimal amount of time. In this transient model, variations of thermal properties, plasma shielding, and phase change are considered. Ablation depth was measured using a 3D optical profiler. Calculated depths are in good agreement with measured values on laser treated titanium surfaces. The proposed model can be applied to a wide range of materials and laser systems.

  4. Chirality effect on nearly half-metallic properties in systematic endo-doping of 3d transition metals of narrow carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Malehmir, M.; Khoshnevisan, B.

    2016-10-01

    Spin polarized density functional calculations were employed to study chirality effect on electronic and magnetic properties of 3d transition metals (TMs) endo-doped co-diameter (∼7 Å) narrow (5,5) and (9,0) single walled carbon nanotubes (CNTs). Various magnetizations up to ∼6μB was obtained for different 3dTM-CNT systems (recall that the magnetization of fcc structure cobalt is ∼1.6μB). In addition nearly half-metallic magnetic behavior has been observed for the most of considered systems. These results would be useful for spintronic and nano-magnetic technology.

  5. 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.

  6. 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

  7. 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.

  8. Synthesis and characterization of different metal oxide nanostructures by simple electrolysis based oxidation of metals.

    PubMed

    Singh, Dinesh Pratap; Srivastava, Onkar Nath

    2009-09-01

    We report the Synthesis of different metal oxide (Cu2O, SnO2, Fe3O4 and PbO2) nanostructures by simple electrolysis based oxidation of metals (Cu, Sn, Fe and Pb). We have utilized the two electrode set up for the electrolysis and used different metal electrodes as anode and platinum as cathode. The synthesized nanomaterials were delaminated in the electrolyte. The microstructural characterization of synthesized materials in electrolytes after electrolysis at different electrode potentials revealed that the nanostructures strongly depend on the applied voltage between the electrodes. Various nanostructures (nanothreads, nanowires, nanocubes, nanotetrapods and hexagons-like) of metal oxides have been synthesized by this method. In case of copper electrode we have found nanothreads and nanowires of cuprous oxide. Tin electrode resulted nanothreads, nanotetrapod and nanocube like structures of tin oxide. Iron electrode resulted, nanowire like structures of iron oxide and lead sheet transformed into hexagon like and six petals like structures of lead oxide.

  9. Noble-metal nanostructures on carburized W(110)

    PubMed Central

    Bachmann, Magdalena; Memmel, Norbert; Bertel, Erminald

    2011-01-01

    Noble metal nanostructures of Au, Ag and Cu were prepared on two types of carbon-modified W(110) surfaces—R(15 × 12) and R(15 × 3)—and investigated by means of scanning tunneling microscopy. For all deposited metals qualitatively the same behaviour is observed: On the R(15 × 12)-template always isotropic clusters are formed. In contrast, on the R(15 × 3)-substrate the anisotropy of the nanostructures can be tuned from clusters at low temperatures via thin nanowires to thicker nanobars at high deposition temperatures. At intermediate temperatures on the R(15 × 3) the anisotropic Au nanowires arrange themselves into straight lines along domain boundaries induced by deposition of the Au metal. Similarities and differences to Au nanostructures as recently reported by Varykhalov et al. [A. Varykhalov, O. Rader, W. Gudat. Physical Review B 77, 035412 (2008).] are discussed. PMID:21779133

  10. Wafer Scale Phase-Engineered 1T- and 2H-MoSe2 /Mo Core-Shell 3D-Hierarchical Nanostructures toward Efficient Electrocatalytic Hydrogen Evolution Reaction.

    PubMed

    Qu, Yindong; Medina, Henry; Wang, Sheng-Wen; Wang, Yi-Chung; Chen, Chia-Wei; Su, Teng-Yu; Manikandan, Arumugam; Wang, Kuangye; Shih, Yu-Chuan; Chang, Je-Wei; Kuo, Hao-Chung; Lee, Chi-Yung; Lu, Shih-Yuan; Shen, Guozhen; Wang, Zhiming M; Chueh, Yu-Lun

    2016-11-01

    The necessity for new sources for greener and cleaner energy production to replace the existing ones has been increasingly growing in recent years. Of those new sources, the hydrogen evolution reaction has a large potential. In this work, for the first time, MoSe2 /Mo core-shell 3D-hierarchical nanostructures are created, which are derived from the Mo 3D-hierarchical nanostructures through a low-temperature plasma-assisted selenization process with controlled shapes grown by a glancing angle deposition system.

  11. Height control of laser metal-wire deposition based on iterative learning control and 3D scanning

    NASA Astrophysics Data System (ADS)

    Heralić, Almir; Christiansson, Anna-Karin; Lennartson, Bengt

    2012-09-01

    Laser Metal-wire Deposition is an additive manufacturing technique for solid freeform fabrication of fully dense metal structures. The technique is based on robotized laser welding and wire filler material, and the structures are built up layer by layer. The deposition process is, however, sensitive to disturbances and thus requires continuous monitoring and adjustments. In this work a 3D scanning system is developed and integrated with the robot control system for automatic in-process control of the deposition. The goal is to ensure stable deposition, by means of choosing a correct offset of the robot in the vertical direction, and obtaining a flat surface, for each deposited layer. The deviations in the layer height are compensated by controlling the wire feed rate on next deposition layer, based on the 3D scanned data, by means of iterative learning control. The system is tested through deposition of bosses, which is expected to be a typical application for this technique in the manufacture of jet engine components. The results show that iterative learning control including 3D scanning is a suitable method for automatic deposition of such structures. This paper presents the equipment, the control strategy and demonstrates the proposed approach with practical experiments.

  12. Direct-Write 3D Nanoprinting of Plasmonic Structures

    DOE PAGES

    Winkler, Robert; Schmidt, Franz-Philipp; Karl-Franzens Univ.; ...

    2016-11-23

    During the past decade, significant progress has been made in the field of resonant optics ranging from fundamental aspects to concrete applications. And while several techniques have been introduced for the fabrication of highly defined metallic nanostructures, the synthesis of complex, free-standing three-dimensional (3D) structures is still an intriguing, but so far intractable, challenge. Here, we demonstrate a 3D direct-write synthesis approach that addresses this challenge. Specifically, we succeeded in the direct-write fabrication of 3D nanoarchitectures via electron-stimulated reactions, which are applicable on virtually any material and surface morphology. Furthermore, by that, complex 3D nanostructures composed of highly compact, puremore » gold can be fabricated, which reveal strong plasmonic activity and pave the way for a new generation of 3D nanoplasmonic architectures that can be printed on-demand.« less

  13. Direct-Write 3D Nanoprinting of Plasmonic Structures.

    PubMed

    Winkler, Robert; Schmidt, Franz-Philipp; Haselmann, Ulrich; Fowlkes, Jason D; Lewis, Brett B; Kothleitner, Gerald; Rack, Philip D; Plank, Harald

    2017-03-08

    During the past decade, significant progress has been made in the field of resonant optics ranging from fundamental aspects to concrete applications. While several techniques have been introduced for the fabrication of highly defined metallic nanostructures, the synthesis of complex, free-standing three-dimensional (3D) structures is still an intriguing, but so far intractable, challenge. In this study, we demonstrate a 3D direct-write synthesis approach that addresses this challenge. Specifically, we succeeded in the direct-write fabrication of 3D nanoarchitectures via electron-stimulated reactions, which are applicable on virtually any material and surface morphology. By that, complex 3D nanostructures composed of highly compact, pure gold can be fabricated, which reveal strong plasmonic activity and pave the way for a new generation of 3D nanoplasmonic architectures that can be printed on-demand.

  14. Direct-Write 3D Nanoprinting of Plasmonic Structures

    SciTech Connect

    Winkler, Robert; Schmidt, Franz-Philipp; Haselmann, Ulrich; Fowlkes, Jason D.; Lewis, Brett B.; Kothleitner, Gerald; Rack, Philip D.; Plank, Harald

    2016-11-23

    During the past decade, significant progress has been made in the field of resonant optics ranging from fundamental aspects to concrete applications. And while several techniques have been introduced for the fabrication of highly defined metallic nanostructures, the synthesis of complex, free-standing three-dimensional (3D) structures is still an intriguing, but so far intractable, challenge. Here, we demonstrate a 3D direct-write synthesis approach that addresses this challenge. Specifically, we succeeded in the direct-write fabrication of 3D nanoarchitectures via electron-stimulated reactions, which are applicable on virtually any material and surface morphology. Furthermore, by that, complex 3D nanostructures composed of highly compact, pure gold can be fabricated, which reveal strong plasmonic activity and pave the way for a new generation of 3D nanoplasmonic architectures that can be printed on-demand.

  15. 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).

  16. 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.

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

    PubMed Central

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

    2016-01-01

    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/cm2 over 80 cycles. PMID:26929378

  18. Nano-structured metallic amyloid fibril networks

    NASA Astrophysics Data System (ADS)

    Batzli, Kiersten; Love, Brian

    2014-03-01

    Amyloid proteins form high aspect ratio fibrillar structures with great chemical and physical stability under specific conditions. By examining the produced networks as novel materials we can envision uses for these high aspect ratio fibrillar structures. Produced fibril networks can be used as templates for the creation of high surface area metallic meshes that may be of use as catalysts or in electronic applications. We have formed fibrillar networks from porcine insulin and have characterized them by TEM, showing that by varying environmental conditions, such as strain rate, the resulting network morphologies may be influenced. We have used electroless deposition techniques to coat insulin fibrils with platinum to produce metallized networks thought to have high catalytic activity. We will present our experience using these coated fibrils to facilitate the reduction of nitrophenol to aminophenol using UV-visible spectroscopy as a gauge.

  19. 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).

  20. 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.

  1. 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.

  2. Ultrafast dynamics of femtosecond laser-induced nanostructure formation on metals

    NASA Astrophysics Data System (ADS)

    Hwang, Taek Yong; Vorobyev, A. Y.; Guo, Chunlei

    2009-09-01

    We perform a comparison study on femtosecond laser-induced nanostructures on three noble metals, Cu, Ag, and Au. Under identical experimental conditions, the three metals each gain a different amount of surface area increase resulting from nanostructuring. We show that the different surface area increase from nanostructuring directly relates to the competition of two ultrafast processes, electron-phonon coupling and hot electron diffusion, following femtosecond laser heating of metals.

  3. 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.

  4. Oxidized carbon fiber supported vertical WS2 nanosheets arrays as efficient 3 D nanostructure electrocatalyts for hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Shang, Xiao; Yan, Kai-Li; Liu, Zi-Zhang; Lu, Shan-Shan; Dong, Bin; Chi, Jing-Qi; Li, Xiao; Liu, Yan-Ru; Chai, Yong-Ming; Liu, Chen-Guang

    2017-04-01

    Oxidized carbon fiber (oCF) as support successfully realizes the vertical growth of uniform WS2 nanosheets arrays for efficient hydrogen evolution reaction (HER) via a facile hydrothermal process. Thanks to oxygen functional groups on oCF, vertical WS2 nanosheets structures have grown more easily on oCF, which can provide better dispersion, short charge transfer distance and more exposed active sites for HER in comparison with bulk WS2 and WS2 nanosheets on bare carbon fiber (CF) fabricated at the same condition. The electrochemical measurements confirmed that WS2/oCF possesses better HER activity than bulk WS2 and WS2/CF. Especially, the 10-h stability with unchanged vertical WS2 nanosheets morphology further demonstrate the positive effect of oxygen functional groups on the enhanced vertical structure and close combination between WS2 and oCF. It may offer a facile way to realize more exposed active sites from stable electrocatalyst hybrids of transition metal sulfides by surface oxidization of carbon supports.

  5. Fabrication of 3D components by laser-aided direct metal deposition

    NASA Astrophysics Data System (ADS)

    Mazumder, Jyotirmoy; Qi, Huan

    2005-03-01

    Breinan and Kear first reported fabrication of three-dimensional metallic components via layer by layer laser cladding in 1978 and subsequently a patent was issued to Brown et al. in 1982. Recently, various groups are working world wide on different types of layered manufacturing techniques for fabrication of near net shape metallic components. Integration of lasers with multi-axis presently available CNC machines, CAD/CAM, sensors and powder metal delivery through co-axial nozzles along with the laser beam are the main innovations for fabrication of 3-Dimensional components. Continuous corrective measures during the manufacturing process are necessary to fabricate net shape functional parts with close tolerances and acceptable residual stress. The closed loop Direct Metal Deposition(DMD) System, using an optical feedback loop along with a CNC working under the instructions from a CAD/CAM software, indicate that it can produce three dimensional components directly from the CAD data eliminating intermediate machining and reduces final machining considerably. This technology is now being commercialized.

  6. Direct writing of metal nanostructures: lithographic tools for nanoplasmonics research.

    PubMed

    Leggett, Graham J

    2011-03-22

    Continued progress in the fast-growing field of nanoplasmonics will require the development of new methods for the fabrication of metal nanostructures. Optical lithography provides a continually expanding tool box. Two-photon processes, as demonstrated by Shukla et al. (doi: 10.1021/nn103015g), enable the fabrication of gold nanostructures encapsulated in dielectric material in a simple, direct process and offer the prospect of three-dimensional fabrication. At higher resolution, scanning probe techniques enable nanoparticle particle placement by localized oxidation, and near-field sintering of nanoparticulate films enables direct writing of nanowires. Direct laser "printing" of single gold nanoparticles offers a remarkable capability for the controlled fabrication of model structures for fundamental studies, particle-by-particle. Optical methods continue to provide a powerful support for research into metamaterials.

  7. 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.

  8. Chemically Modified Metal Oxide Nanostructure for Photoelectrochemical Water Splitting

    NASA Astrophysics Data System (ADS)

    Wang, Gongming

    Hydrogen gas is chemical fuel with high energy density, and represents a clean, renewable and carbon-free burning fuel, which has the potential to solve the more and more urgent energy crisis in today's society. Inspired by natural photosynthesis, artificial photosynthesis to generate hydrogen energy has attracted a lot of attentions in the field of chemistry, physics and material. Photoelectrochemical water splitting based on semiconductors represents a green and low cost method to generate hydrogen fuel. However, the current overall efficiency of solar to hydrogen is quite low, due to some intrinsic limitations such as bandgap, diffusion distance, carrier lifetime and photostability of semiconductors. Although nanostructured semiconductors can improve their photoelectrochemical water splitting performance to some extent, by increasing electrolyte accessible area and shortening minority carrier diffusion distance, nanostructure engineering cannot change their intrinsic electronic properties. Recent development in chemically modified nanostructures such as surface catalyst decoration, element doping, plasmonic modification and interfacial hetero-junction design have led to significant advancement in the photoelectrochemical water splitting, by improving surface reaction kinetics and charge separation, transportation and collection efficiency. In this thesis, I will give a detailed discussion on the chemically modified metal oxide nanostructures for photoelectrocemical hydrogen generation, with a focus on the element doping, hydrogen treatment and catalyst modification. I have demonstrated nitrogen doping on ZnO and Ti doping on hematite can improve their photoelectrochemical performance. In addition, we found hydrogen treatment is a general and effective method to improve the photocatalytic performance, by increasing their carrier desities. Hydrogen treatment has been demonstrated on TiO2, WO3 and BiVO4. In the end, we also used electrochemical catalyt to modify

  9. 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.

  10. 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.

  11. 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.

  12. Quantum transport in 3D Weyl semimetals: Is there a metal-insulator transition?

    NASA Astrophysics Data System (ADS)

    Ziegler, Klaus

    2016-12-01

    We calculate the transport properties of three-dimensional Weyl fermions in a disordered environment. The resulting conductivity depends only on the Fermi energy and the scattering rate. First we study the conductivity at the spectral node for a fixed scattering rate and obtain a continuous transition from an insulator at weak disorder to a metal at stronger disorder. Within the self-consistent Born approximation the scattering rate depends on the Fermi energy. Then it is crucial that the limits of the conductivity for a vanishing Fermi energy and a vanishing scattering rate do not commute. As a result, there is also metallic behavior in the phase with vanishing scattering rate and only a quantum critical point remains as an insulating phase. The latter turns out to be a critical fixed point in terms of a renormalization-group flow.

  13. A Metal Organic Framework with Spherical Protein Nodes: Rational Chemical Design of 3D Protein Crystals.

    PubMed

    Sontz, Pamela A; Bailey, Jake B; Ahn, Sunhyung; Tezcan, F Akif

    2015-09-16

    We describe here the construction of a three-dimensional, porous, crystalline framework formed by spherical protein nodes that assemble into a prescribed lattice arrangement through metal-organic linker-directed interactions. The octahedral iron storage enzyme, ferritin, was engineered in its C3 symmetric pores with tripodal Zn coordination sites. Dynamic light scattering and crystallographic studies established that this Zn-ferritin construct could robustly self-assemble into the desired bcc-type crystals upon coordination of a ditopic linker bearing hydroxamic acid functional groups. This system represents the first example of a ternary protein-metal-organic crystalline framework whose formation is fully dependent on each of its three components.

  14. Tunable electronic and magnetic properties in stanene by 3d transition metal atoms absorption

    NASA Astrophysics Data System (ADS)

    Xing, Dan-Xu; Ren, Ceng-Ceng; Zhang, Shu-Feng; Feng, Yong; Chen, Xin-Lian; Zhang, Chang-Wen; Wang, Pei-Ji

    2017-03-01

    The electronic and magnetic properties of transition metal (TM) atoms (V, Cr, Mn, Fe, Co, Ni) adsorption on stanene are investigated by first-principles calculations. The results indicate that the TM atoms prefer to be relaxed on a H site on stanene except V atom which lies on the valley site. Fe-absorbed stanene is a spin gapless semiconductor with up-spin electron and down-spin hole carriers allowing the coexistence of charge current and the pure spin current. Co-absorbed stanene lies in the half metal phase. The V-, Cr-, Mn-, and Cu-absorbed stanene turn the stanene into metal, while Ni- and Zn-absorbed stanene open a narrow band gap. For V-, Cr-, Mn-, Fe-, and Co-absorbed stanene, the magnetic moment of the TM will survive while the Ni-, Cu-, and Zn-absorbed stanene will be non-magnetic material. These findings may have great potential in the design of new electrically controllable spintronic devices.

  15. 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

  16. Multi-scale Characterisation of the 3D Microstructure of a Thermally-Shocked Bulk Metallic Glass Matrix Composite

    NASA Astrophysics Data System (ADS)

    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.

  17. Localization of metal targets by time reversal of electromagnetic waves . 3D-numerical and experimental study

    NASA Astrophysics Data System (ADS)

    Benhamouche, Mehdi; Bernard, Laurent; Serhir, Mohammed; Pichon, Lionel; Lesselier, Dominique

    2013-11-01

    This paper proposes a criterion for locating obstacles by time reversal (TR) of electromagnetic (EM) waves based on the analysis of the density of EM energy map in time domain. Contrarily to a monochromatic study of the TR, the wide-band approach requires to determine the instant of the wave focus. This enables us to locate the focal spots that are indicative of the positions. The criterion proposed is compared to the inverse of the minimum entropy criterion as used in the literature [X. Xu, E.L. Miller, C.M. Rappaport, IEEE Trans. Geosci. Remote Sens. 41, 1804 (2003)]. An application for the localization of 3D metal targets is proposed using finite integration technique (FIT) as computational tool at the modeling stage. An experimental validation is presented for canonical three-dimensional configurations with two kinds of metal objects. Contribution to the Topical Issue "Numelec 2012", Edited by Adel Razek.

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

    SciTech Connect

    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.

  19. 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).

  20. Compact Bragg grating with embedded metallic nano-structures.

    PubMed

    Mu, Jianwei; Li, Xun; Huang, Wei-Ping

    2010-07-19

    A compact Bragg grating with embedded gapped metallic nano-structures is proposed and investigated theoretically. The Bragg grating consists of periodic planar metallic strips embedded in a dielectric waveguide. The grating exhibits distinct polarization characteristics due to its underlying working mechanisms of the metallic nano-strips. The grating can be considered as insulator-metal-insulator surface plasmonic polariton waveguide grating with improved light confinement for TM polarized waves. For the TE waves, significant field mismatch between metal and non-metal sections of the grating results in strong reflection. Comparison with the conventional deeply-etched grating on the same waveguide structures reveals interesting characteristics. It is concluded that the two types of grating structures share similar guidance, reflection and loss mechanisms for the TE modes. The spectral characteristics and their dependences on grating duty cycle are drastically different for the TM modes, mainly due to the SPP effect for the metal. Although the proposed grating performs slightly worse comparing to the deeply-etched grating for TE waves, its fabrication process should be easier since there will be no narrow trench (in sub-microns) deep-etching process (up to a few microns in depth) involved.

  1. Branching ratio and L2 + L3 intensities of 3d-transition metals in phthalocyanines and the amine complexes

    PubMed

    Koshino; Kurata; Isoda; Kobayashi

    2000-08-01

    L(2,3) inner-shell excitation spectra were obtained by electron energy-loss spectroscopy (EELS) for the divalent first transition series metals in phthalocyanine complexes (MPc) such as titanium oxide phthalocyanine (TiOPc), fluoro-chromium phthalocyanine (CrFPc), manganese phthalocyanine (MnPc), iron phthalocyanine (FePc), cobalt phthalocyanine (CoPc), nickel phthalocyanine (NiPc) and copper phthalocyanine (CuPc). It was found that the value of normalized total intensity of I(L2 + L3) was nearly proportional to the formal electron vacancies of each 3d-state, and the values of the branching ratio, I(L3)/I((L2 + L3), represented a high-spin-state rather than low-spin-state for MnPc, FePc and NiPc. EELS was also applied to charge-transfer complexes of FePc with an amine such as pyridine or gamma-picoline. It was concluded that their I(L2 + L3) intensity of Fe showed the decrease in vacancies of 3d-states on the formation of the charge-transfer complex with these amines, which suggests some electron transfer from the amine to Fe in phthalocyanine. The EELS study provides beneficial information for investigating the electronic states of the specific metal sites in organic materials.

  2. 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.

  3. 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.

  4. 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

  5. Density Functional Theory of Open-Shell Systems. The 3d-Series Transition-Metal Atoms and Their Cations.

    PubMed

    Luo, Sijie; Averkiev, Boris; Yang, Ke R; Xu, Xuefei; Truhlar, Donald G

    2014-01-14

    The 3d-series transition metals (also called the fourth-period transition metals), Sc to Zn, are very important in industry and biology, but they provide unique challenges to computing the electronic structure of their compounds. In order to successfully describe the compounds by theory, one must be able to describe their components, in particular the constituent atoms and cations. In order to understand the ingredients required for successful computations with density functional theory, it is useful to examine the performance of various exchange-correlation functionals; we do this here for 4s(N)3d(N') transition-metal atoms and their cations. We analyze the results using three ways to compute the energy of the open-shell states: the direct variational method, the weighted-averaged broken symmetry (WABS) method, and a new broken-symmetry method called the reinterpreted broken symmetry (RBS) method. We find the RBS method to be comparable in accuracy with the WABS method. By examining the overall accuracy in treating 18 multiplicity-changing excitations and 10 ionization potentials with the RBS method, 10 functionals are found to have a mean-unsigned error of <5 kcal/mol, with ωB97X-D topping the list. For local density functionals, which are more practical for extended systems, the M06-L functional is the most accurate. And by combining the results with our previous studies of p-block and 4d-series elements as well as databases for alkyl bond dissociation, main-group atomization energies, and π-π noncovalent interactions, we find five functionals, namely, PW6B95, MPW1B95, M08-SO, SOGGA11-X, and MPWB1K, to be highly recommended. We also studied the performance of PW86 and C09 exchange functionals, which have drawn wide interest in recent studies due to their claimed ability to reproduce Hartree-Fock exchange at long distance. By combining them with four correlation functionals, we find the performance of the resulting functionals disappointing both for 3d

  6. 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.

  7. Synthesis and bioanalytical applications of specific-shaped metallic nanostructures: a review.

    PubMed

    Tokonami, Shiho; Yamamoto, Yojiro; Shiigi, Hiroshi; Nagaoka, Tsutomu

    2012-02-24

    Many successful synthesis routes for producing different shapes of metallic nanostructures, including sphere, rod, cube, and hollow shapes, have been developed in the past few decades. Many applications using these nanostructures have been studied because the outstanding properties of the nanostructures are not exhibited by their bulk-state counterparts. This review paper reports some recent developments in clinical and biosensor applications. The first part focused on the synthesis methods of metallic nanostructures having various shapes along with their optical properties. The second and third part is an introduction of the gold nanoparticle assemblies and arrays, explaining the conjugation methods of metallic nanostructures with biological entities. The final part reviews on the recent bioanalytical applications using various shapes of metallic nanostructures.

  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. Optical stability of 3d transition metal ions doped-cadmium borate glasses towards γ-rays interaction

    NASA Astrophysics Data System (ADS)

    Marzouk, M.; ElBatal, H.; Eisa, W.

    2016-07-01

    This work reports the preparation of glasses of binary cadmium borate with the basic composition (mol% 45 CdO 55 B2O3) and samples of the same composition containing 0.2 wt% dopants of 3d transition metal (TM) oxides (TiO2 → CuO). The glasses have been investigated by combined optical and Fourier Transform infrared spectroscopic measurements before and after being subjected to gamma irradiation with a dose of 8 Mrad (8 × 104 Gy). Optical absorption of the undoped glass before irradiation reveals strong charge transfer UV absorption which is related to the presence of unavoidable contaminated trace iron impurities (mainly Fe3+) within the raw materials used for the preparation of the base cadmium borate glass. The optical spectra of the 3d TM ions exhibit characteristic bands which are related the stable oxidation state of the 3d TM ions within the host glass. Gamma irradiation produces some limited variations in the optical spectra due to the stability of the host glass containing high percent 45 mol% of heavy metal oxide (CdO) which causes some shielding effects towards irradiation. From the absorption edge data, the values of the optical band gap Eopt and Urbach energy (∆E) have been calculated. The values of the optical energy gap are found to be dependent on the glass composition. Infrared absorption spectral measurements reveal characteristic absorption bands due to both triangular and tetrahedral borate groups with the BO3 units vibrations more intense than BO4 units due to the known limit value for the change of BO3 to BO4 groups. The introduction of 3d TM ions with the doping level (0.2 wt%) causes no changes in the number or position of the IR bands because of the presence of TM ions in modifying sites in the glass network. It is observed that gamma irradiation causes some limited changes in the FT-IR spectral bands due to the stability of the host heavy cadmium borate glass.

  10. 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.

  11. 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.

  12. Relative stability of normal vs. inverse spinel for 3d transition metal oxides as lithium intercalation cathodes.

    PubMed

    Bhattacharya, Jishnu; Wolverton, C

    2013-05-07

    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.

  13. 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.

  14. Time-dependent 3-D modelling of laser surface heating for the hardening of metallic materials

    NASA Astrophysics Data System (ADS)

    Colombo, V.; Mentrelli, A.; Trombetti, T.

    2003-12-01

    A numerical code for the time-dependent three-dimensional modelling of the laser surface heating for the hardening of metallic materials has been developed by the authors. The temperature-dependence of the thermal properties of the material (stainless steel) is taken into account in the frame of a heating process that doesn’t lead to material melting or evaporation. Calculations have been carried out for various dimensions of the parallelepiped-shaped and of the square-shaped spot of the laser beam, as well as for different scanning velocity and for different levels of the laser source power. Various patterns of the laser spot path have also been studied, including a single-pass hardening pattern, a double-pass hardening pattern with and without overlapping, multiple discontinuous and continuous hardening patterns and spiral hardening patterns. The presented results show how the proposed model can be usefully employed in the prediction of the time-evolution of temperature distribution which arises in the workpiece as a consequence of the laser-workpiece interaction under operating conditions typically encountered in industrial applications of the laser hardening process.

  15. Structural, electronic and magnetic properties of 3d metal trioxide clusters-doped monolayer graphene: A first-principles study

    NASA Astrophysics Data System (ADS)

    Rafique, Muhammad; Shuai, Yong; Tan, He-Ping; Hassan, Muhammad

    2017-03-01

    We present first-principles density-functional calculations for the structural, electronic and magnetic properties of monolayer graphene doped with 3d (Ti, V, Cr, Fe, Co, Mn and Ni) metal trioxide TMO3 halogen clusters. In this paper we used two approaches for 3d metal trioxide clusters (i) TMO3 halogen cluster was embedded in monolayer graphene substituting four carbon (C) atoms (ii) three C atoms were substituted by three oxygen (O) atoms in one graphene ring and TM atom was adsorbed at the hollow site of O atoms substituted graphene ring. All the impurities were tightly bonded in the graphene ring. In first case of TMO3 doped graphene layer, the bond length between Csbnd O atom was reduced and bond length between TM-O atom was increased. In case of Cr, Fe, Co and Ni atoms substitution in between the O atoms, leads to Fermi level shifting to conduction band thereby causing the Dirac cone to move into valence band, however a band gap appears at high symmetric K-point. In case of TiO3 and VO3 substitution, system exhibits semiconductor properties. Interestingly, TiO3-substituted system shows dilute magnetic semiconductor behavior with 2.00 μB magnetic moment. On the other hand, the substitution of CoO3, CrO3, FeO3 and MnO3 induced 1.015 μB, 2.347 μB, 2.084 μB and 3.584 μB magnetic moment, respectively. In second case of O atoms doped in graphene and TM atoms adsorbed at the hollow site, the O atom bulges out of graphene plane and bond length between TM-O atom is increased. After TM atoms adsorption at the O substituted graphene ring the Fermi level (EF) shifts into conduction band. In case of Cr and Ni adsorption, system displays indirect band gap semiconductor properties with 0.0 μB magnetic moment. Co adsorption exhibits dilute magnetic semiconductor behavior producing 0.916 μB magnetic moment. Fe, Mn, Ti and V adsorption introduces band gap at high symmetric K-point also inducing 1.54 μB, 0.9909 μB, 1.912 μB, and 0.98 μB magnetic moments, respectively

  16. 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.

  17. 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

  18. 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.

  19. Self-assembly of metal nanostructures on binary alloy surfaces.

    PubMed

    Duguet, T; Han, Yong; Yuen, Chad; Jing, Dapeng; Unal, Barış; Evans, J W; Thiel, P A

    2011-01-18

    Deposition of metals on binary alloy surfaces offers new possibilities for guiding the formation of functional metal nanostructures. This idea is explored with scanning tunneling microscopy studies and atomistic-level analysis and modeling of nonequilibrium island formation. For Au/NiAl(110), complex monolayer structures are found and compared with the simple fcc(110) bilayer structure recently observed for Ag/NiAl(110). We also consider a more complex codeposition system, (Ni + Al)/NiAl(110), which offers the opportunity for fundamental studies of self-growth of alloys including deviations for equilibrium ordering. A general multisite lattice-gas model framework enables analysis of structure selection and morphological evolution in these systems.

  20. Diffusion and surface alloying of gradient nanostructured metals

    PubMed Central

    Lu, Ke

    2017-01-01

    Gradient nanostructures (GNSs) have been optimized in recent years for desired performance. The diffusion behavior in GNS metals is crucial for understanding the diffusion mechanism and relative characteristics of different interfaces that provide fundamental understanding for advancing the traditional surface alloying processes. In this paper, atomic diffusion, reactive diffusion, and surface alloying processes are reviewed for various metals with a preformed GNS surface layer. We emphasize the promoted atomic diffusion and reactive diffusion in the GNS surface layer that are related to a higher interfacial energy state with respect to those in relaxed coarse-grained samples. Accordingly, different surface alloying processes, such as nitriding and chromizing, have been modified significantly, and some diffusion-related properties have been enhanced. Finally, the perspectives on current research in this field are discussed. PMID:28382244

  1. Application of ATHLET/DYN3D coupled codes system for fast liquid metal cooled reactor steady state simulation

    NASA Astrophysics Data System (ADS)

    Ivanov, V.; Samokhin, A.; Danicheva, I.; Khrennikov, N.; Bouscuet, J.; Velkov, K.; Pasichnyk, I.

    2017-01-01

    In this paper the approaches used for developing of the BN-800 reactor test model and for validation of coupled neutron-physic and thermohydraulic calculations are described. Coupled codes ATHLET 3.0 (code for thermohydraulic calculations of reactor transients) and DYN3D (3-dimensional code of neutron kinetics) are used for calculations. The main calculation results of reactor steady state condition are provided. 3-D model used for neutron calculations was developed for start reactor BN-800 load. The homogeneous approach is used for description of reactor assemblies. Along with main simplifications, the main reactor BN-800 core zones are described (LEZ, MEZ, HEZ, MOX, blankets). The 3D neutron physics calculations were provided with 28-group library, which is based on estimated nuclear data ENDF/B-7.0. Neutron SCALE code was used for preparation of group constants. Nodalization hydraulic model has boundary conditions by coolant mass-flow rate for core inlet part, by pressure and enthalpy for core outlet part, which can be chosen depending on reactor state. Core inlet and outlet temperatures were chosen according to reactor nominal state. The coolant mass flow rate profiling through the core is based on reactor power distribution. The test thermohydraulic calculations made with using of developed model showed acceptable results in coolant mass flow rate distribution through the reactor core and in axial temperature and pressure distribution. The developed model will be upgraded in future for different transient analysis in metal-cooled fast reactors of BN type including reactivity transients (control rods withdrawal, stop of the main circulation pump, etc.).

  2. 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.

  3. A general solution-phase approach to oriented nanostructured films of metal chalcogenides on metal foils: the case of nickel sulfide.

    PubMed

    Zhang, Lizhi; Yu, Jimmy C; Mo, Maosong; Wu, Ling; Li, Quan; Kwong, Kwan Wai

    2004-07-07

    Oriented films of nickel sulfide nanostructures, ranging from hierarchical dendrites to nanobelts and nanorods, were hydrothermally grown on Ni foils. This approach has proven to be a general method for preparing nanostructured metal chalcogenides films on corresponding metal foils.

  4. Metal nanocrystal/metal-organic framework core/shell nanostructure from selective self-assembly induced by localization of metal ion precursors on nanocrystal surface.

    PubMed

    Ohhashi, Takashi; Tsuruoka, Takaaki; Matsuyama, Tetsuhiro; Takashima, Yohei; Nawafune, Hidemi; Minami, Hideto; Akamatsu, Kensuke

    2015-08-01

    Metal nanocrystal/metal-organic framework core/shell nanostructures have been constructed using metal ion-trapped nanocrystals as scaffolds through a selective self-assembly of framework components on the nanocrystal surfaces. The resulting nanostructures exhibit unique catalytic activity toward nitrophenol analogs.

  5. 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.

  6. 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.

  7. 3D Online Submicron Scale Observation of Mixed Metal Powder's Microstructure Evolution in High Temperature and Microwave Compound Fields

    PubMed Central

    Xu, Feng; Hu, Xiao-fang; Xiao, Yu; Xiao, Ti-qiao

    2014-01-01

    In order to study the influence on the mechanical properties caused by microstructure evolution of metal powder in extreme environment, 3D real-time observation of the microstructure evolution of Al-Ti mixed powder in high temperature and microwave compound fields was realized by using synchrotron radiation computerized topography (SR-CT) technique; the spatial resolution was enhanced to 0.37 μm/pixel through the designed equipment and the introduction of excellent reconstruction method for the first time. The process of microstructure evolution during sintering was clearly distinguished from 2D and 3D reconstructed images. Typical sintering parameters such as sintering neck size, porosity, and particle size of the sample were presented for quantitative analysis of the influence on the mechanical properties and the sintering kinetics during microwave sintering. The neck size-time curve was obtained and the neck growth exponent was 7.3, which indicated that surface diffusion was the main diffusion mechanism; the reason was the eddy current loss induced by the external microwave fields providing an additional driving force for mass diffusion on the particle surface. From the reconstructed images and the curve of porosity and average particle size versus temperature, it was believed that the presence of liquid phase aluminum accelerated the densification and particle growth. PMID:24737986

  8. 3D online submicron scale observation of mixed metal powder's microstructure evolution in high temperature and microwave compound fields.

    PubMed

    Kang, Dan; Xu, Feng; Hu, Xiao-fang; Dong, Bo; Xiao, Yu; Xiao, Ti-qiao

    2014-01-01

    In order to study the influence on the mechanical properties caused by microstructure evolution of metal powder in extreme environment, 3D real-time observation of the microstructure evolution of Al-Ti mixed powder in high temperature and microwave compound fields was realized by using synchrotron radiation computerized topography (SR-CT) technique; the spatial resolution was enhanced to 0.37  μm/pixel through the designed equipment and the introduction of excellent reconstruction method for the first time. The process of microstructure evolution during sintering was clearly distinguished from 2D and 3D reconstructed images. Typical sintering parameters such as sintering neck size, porosity, and particle size of the sample were presented for quantitative analysis of the influence on the mechanical properties and the sintering kinetics during microwave sintering. The neck size-time curve was obtained and the neck growth exponent was 7.3, which indicated that surface diffusion was the main diffusion mechanism; the reason was the eddy current loss induced by the external microwave fields providing an additional driving force for mass diffusion on the particle surface. From the reconstructed images and the curve of porosity and average particle size versus temperature, it was believed that the presence of liquid phase aluminum accelerated the densification and particle growth.

  9. 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

  10. Effects of oxygen vacancy on 3d transition-metal doped anatase TiO2: First principles calculations

    NASA Astrophysics Data System (ADS)

    Zhao, Ya Fei; Li, Can; Lu, Song; Yan, Li Jin; Gong, Yin Yan; Niu, Leng Yuan; Liu, Xin Juan

    2016-03-01

    In this work, systematic study of the formation energy, crystalline and electronic structures of 3d transition metal (Sc, V, Cr, Mn, Fe, Co and Ni) doped anatase TiO2 specimens with and without oxygen vacancy has been carried out by the first principles calculations. The impurity states located at the band gaps enhance the visible light absorption, and the oxygen vacancy result in the EF move into the CB for some doped systems, which induce the Ti3+ ions and promote the separation of photogenerated carriers. Doping and oxygen vacancy can change the hybrid strength and MP value of TMsbnd O bonding which has the approximately linearly with the band gap.

  11. Spin splitting and reemergence of charge compensation in monolayer WTe2 by 3d transition-metal adsorption.

    PubMed

    Song, Yan; Wang, Xiaocha; Mi, Wenbo

    2017-03-15

    The semimetallic WTe2 has sparked intense interest owing to the non-saturating magnetoresistance, pressure-driven superconductivity and possession of type-II Weyl fermions. The unexpected and fascinating quantum properties are thought to be closely related to its delicate Fermi surface and a special electron-hole-pocket structure. However, in the single-layer limit, the electron-hole-pocket structure is missing owing to the lack of interlayer interaction. Herewith, we demonstrate that 3d transition-metal adsorption is an effective method to modify the electronic properties of monolayer WTe2 by density functional theory. Spin-splitting and spin-degenerate bands are realized in Ti-, V-, Cr-, Mn-, Fe-, and Co- and Sc-, Ni-, Cu-, and Zn-adsorbed systems, respectively. Especially, the reemergence of the electron-hole pockets appears in the Ni-adsorbed system. The calculated results are robust against inclusion of spin-orbit coupling and Coulomb interaction.

  12. 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.

  13. A Triaxial Failure Diagram to predict the forming limit of 3D sheet metal parts subjected to multiaxial stresses

    NASA Astrophysics Data System (ADS)

    Rastellini, F.; Socorro, G.; Forgas, A.; Onate, E.

    2016-08-01

    Accurate prediction of failure and forming limits is essential when modelling sheet metal forming processes. Since traditional Forming Limit Curves (FLCs) are not valid for materials subjected to triaxial loading, a new failure criterion is proposed in this paper based on the stress triaxility and the effective plastic strain accumulated during the history of material loading. Formability zones are identified inside the proposed Triaxial Failure Diagram (TFD). FLCs may be mapped into the TFD defining a new Triaxial Failure Curve, or it can be defined by triaxial failure experiments. Several TFD examples are validated and constrasted showing acceptable accuracy in the numerical prediction of forming failure/limit of 3D thick sheet parts.

  14. Positional isomerism-driven two 3D pillar-layered metal-organic frameworks: Syntheses, topological structures and photoluminescence properties

    SciTech Connect

    Sun, Yayong; Zhao, Siwei; Ma, Haoran; Han, Yi; Liu, Kang; Wang, Lei

    2016-06-15

    Two novel three-dimensional (3D) pillar-layered metal-organic frameworks (MOFs), namely [Zn{sub 2}(μ{sub 2}-OH)(boaba)(1,4-bmimb)]{sub n} (1) and {[Zn_5K_2(μ_2-H_2O)_2(boaba)_4(1,2-bmimb)_2(H_2O)_2]·H_2O}{sub n} (2), were prepared by hydrothermal reactions (H{sub 3}boaba=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 (6{sup 3})(6{sup 9}·8)-gra net with binuclear [Zn{sub 2}(μ{sub 2}-OH)(COO)]{sup 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. - Graphical abstract: Two novel 3D pillar-layered metal-organic coordination networks with aromatic multicarboxylate anion and bis(imidazole) ligands have been synthesized and structurally characterized. Display Omitted - Highlights: • It is rarely reported that metal-organic frameworks prepared with 3,5-bis-oxyacetate-benzoic acid. • Two metal-organic frameworks based on positional isomeric ligands were synthesized and structurally characterized. • Compond 1 displays unique (3,5)-connected binodal gra topology. • Compound 2 exhibits (4,4,5,9)-connected 4-nodal topology based on the Zn(II)-K(I) heterometal rod-like substructures. • The photoluminescence properties of compound 1 and 2 have been investigated.

  15. 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.

  16. 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.

  17. 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

  18. Metal-insulator transition in 3d transition-metal oxides with ABO 3 and A 2BO 4 type structures

    NASA Astrophysics Data System (ADS)

    Eisaki, H.; Ido, T.; Magoshi, K.; Mochizuki, M.; Yamatsu, H.; Ito, T.; Uchida, S.

    1991-12-01

    3d transition-metal oxides with perovskite and K 2NiF 4 crystal structures, (La,Sr)VO 3, (La,Sr)FeO 3, (La,Sr)CoO 3, LaNiO 3 and (La,Sr) 2NiO 4 systems are investigated focusing on the effect of carrier doping performed by the A-site ion substitution. Both (La,Sr)VO 3 and (La,Sr)CoO 3 systems show an insulator to metal transition by Sr substitution, however, the magnetic behavior differs drastically. The mid-infrared structure induced by Sr substitution is observed in the optical spectra of (La,Sr) 2NiO 4 system. Relation between the behavior of metal-insulator transition and the variation of the electronic and/or spin structure in these systems is discussed in comparison with the high-T c copper oxides.

  19. 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.

  20. 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.

  1. Metallic nanostructure formation limited by the surface hydrogen on silicon.

    PubMed

    Perrine, Kathryn A; Teplyakov, Andrew V

    2010-08-03

    Constant miniaturization of electronic devices and interfaces needed to make them functional requires an understanding of the initial stages of metal growth at the molecular level. The use of metal-organic precursors for metal deposition allows for some control of the deposition process, but the ligands of these precursor molecules often pose substantial contamination problems. One of the ways to alleviate the contamination problem with common copper deposition precursors, such as copper(I) (hexafluoroacetylacetonato) vinyltrimethylsilane, Cu(hfac)VTMS, is a gas-phase reduction with molecular hydrogen. Here we present an alternative method to copper film and nanostructure growth using the well-defined silicon surface. Nearly ideal hydrogen termination of silicon single-crystalline substrates achievable by modern surface modification methods provides a limited supply of a reducing agent at the surface during the initial stages of metal deposition. Spectroscopic evidence shows that the Cu(hfac) fragment is present upon room-temperature adsorption and reacts with H-terminated Si(100) and Si(111) surfaces to deposit metallic copper. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) are used to follow the initial stages of copper nucleation and the formation of copper nanoparticles, and X-ray energy dispersive spectroscopy (XEDS) confirms the presence of hfac fragments on the surfaces of nanoparticles. As the surface hydrogen is consumed, copper nanoparticles are formed; however, this growth stops as the accessible hydrogen is reacted away at room temperature. This reaction sets a reference for using other solid substrates that can act as reducing agents in nanoparticle growth and metal deposition.

  2. An in-depth spectroscopic examination of molecular bands from 3D hydrodynamical model atmospheres. I. Formation of the G-band in metal-poor dwarf stars

    NASA Astrophysics Data System (ADS)

    Gallagher, A. J.; Caffau, E.; Bonifacio, P.; Ludwig, H.-G.; Steffen, M.; Spite, M.

    2016-09-01

    Context. Recent developments in the three-dimensional (3D) spectral synthesis code Linfor3D have meant that for the first time, large spectral wavelength regions, such as molecular bands, can be synthesised with it in a short amount of time. Aims: A detailed spectral analysis of the synthetic G-band for several dwarf turn-off-type 3D atmospheres (5850 ≲ Teff [ K ] ≲ 6550, 4.0 ≤ log g ≤ 4.5, - 3.0 ≤ [Fe/H] ≤-1.0) was conducted, under the assumption of local thermodynamic equilibrium. We also examine carbon and oxygen molecule formation at various metallicity regimes and discuss the impact it has on the G-band. Methods: Using a qualitative approach, we describe the different behaviours between the 3D atmospheres and the traditional one-dimensional (1D) atmospheres and how the different physics involved inevitably leads to abundance corrections, which differ over varying metallicities. Spectra computed in 1D were fit to every 3D spectrum to determine the 3D abundance correction. Results: Early analysis revealed that the CH molecules that make up the G-band exhibited an oxygen abundance dependency; a higher oxygen abundance leads to weaker CH features. Nitrogen abundances showed zero impact to CH formation. The 3D corrections are also stronger at lower metallicity. Analysis of the 3D corrections to the G-band allows us to assign estimations of the 3D abundance correction to most dwarf stars presented in the literature. Conclusions: The 3D corrections suggest that A(C) in carbon-enhanced metal-poor (CEMP) stars with high A(C) would remain unchanged, but would decrease in CEMP stars with lower A(C). It was found that the C/O ratio is an important parameter to the G-band in 3D. Additional testing confirmed that the C/O ratio is an equally important parameter for OH transitions under 3D. This presents a clear interrelation between the carbon and oxygen abundances in 3D atmospheres through their molecular species, which is not seen in 1D.

  3. 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.

  4. Constructing 3D branched nanowire coated macroporous metal oxide electrodes with homogeneous or heterogeneous compositions for efficient solar cells.

    PubMed

    Wu, Wu-Qiang; Xu, Yang-Fan; Rao, Hua-Shang; Feng, Hao-Lin; Su, Cheng-Yong; Kuang, Dai-Bin

    2014-05-05

    Light-harvesting and charge collection have attracted increasing attention in the domain of photovoltaic cells, and can be facilitated dramatically by appropriate design of a photonic nanostructure. However, the applicability of current light-harvesting photoanode materials with single component and/or morphology (such as, particles, spheres, wires, sheets) is still limited by drawbacks such as insufficient electron-hole separation and/or light-trapping. Herein, we introduce a universal method to prepare hierarchical assembly of macroporous material-nanowire coated homogenous or heterogeneous metal oxide composite electrodes (TiO2 -TiO2 , SnO2 -TiO2 , and Zn2 SnO4 -TiO2 ; homogenous refers to a material in which the nanowire and the macroporous material have the same composition, i.e. both are TiO2 . Heterogeneous refers to a material in which the nanowires and the macroporous material have different compositions). The dye-sensitized solar cell based on a TiO2 -macroporous material-TiO2 -nanowire homogenous composition electrode shows an impressive conversion efficiency of 9.51 %, which is much higher than that of pure macroporous material-based photoelectrodes to date.

  5. Insights into bonding interactions and excitation energies of 3d-4f mixed lanthanide transition metal macrocyclic complexes.

    PubMed

    Rabanal-León, Walter A; Murillo-López, Juliana A; Arratia-Pérez, Ramiro

    2016-12-07

    In this contribution, a computational study of equatorial bound tetranuclear macrocycle (butylene linked) [LnZn(HOM(Bu))](3+) (Ln = La(3+), Ce(3+)) complexes was carried out. Here, the electronic structure, bonding interaction and excitation energies were studied within the relativistic density functional theory framework. From the electronic structure analysis, the frontier molecular orbitals (FMOs) were strongly localized in the d-orbitals of the Zn centers and the f-orbitals of the lanthanide ions. Besides, the inner MOs were found to exhibit a π-character from the organic part of the macrocyclic chain. EDA-NOCV was used as a tool for evaluating the bonding interaction, taking the trinuclear metallomacrocycle (ZnHOM(Bu)) and the lanthanide center as fragments. This analysis showed that the interaction between these fragments was slightly covalent; with this covalency being the result of a charge transfer from the metallomacrocyclic ring to the lanthanide. This phenomenon was observed in the deformation density channels obtained from the EDA-NOCV study; in which π- and σ-charge transfer was observed. Finally, the TD-DFT study of the excitation energies evidenced three sets of bands: the first set with the highest intensity represented the ligand to metal charge transfer bands; the second set could be attributed to the 3d-4f electronic transitions between the metal centers; and the third set represented the f-f bands found for the open-shell cerium complex. This class of complexes accomplishes the "antenna effect" principle, which states that highly absorptive transition-metal (TM) complexes can be used to enhance the luminescence of poorly emissive systems, and are introduced in this study as self-sensitizer bimetallic d-f systems with potential applications in near infra-red (NIR) technologies.

  6. Anisotropic Electrical Properties of Nanostructured Metallic Thin Films

    NASA Astrophysics Data System (ADS)

    Ahoujja, Mo; Shah, Piyush; Saragan, Andrew; Elhamri, Said; Guliants, Elena

    2011-03-01

    High surface area, porous, metallic (Ti, Cr) nanorod thin films with columnar microstructure can be deposited using conventional physical vapor deposition technique of E-beam evaporation. The technique relies on the physical vapor deposition onto a static substrate oriented in a position where flux from the source material (Ti, Cr) arrives at oblique angle. The adatoms provides geometrical shadowing which results in growth of nanorod columns in the direction of vapor source. Deposition conditions such as angle of the incoming vapor flux, substrate temperature, surface diffusion etc. have strong influence on the shape and arrangement of the columnar thin films. In this work, we demonstrate the growth and electrical characterization of these nanostructured thin films. Preliminary results on these films exhibit electrical resistivity anisotropy, when characterized by measuring their electrical resistivity using conventional van der pauw method. Origin and possible causes of this resistivity anisotropy is discussed.

  7. Discontinuous Galerkin time-domain computations of metallic nanostructures.

    PubMed

    Stannigel, Kai; König, Michael; Niegemann, Jens; Busch, Kurt

    2009-08-17

    We apply the three-dimensional Discontinuous-Galerkin Time-Domain method to the investigation of the optical properties of bar- and V-shaped metallic nanostructures on dielectric substrates. A flexible finite element-like mesh together with an expansion into high-order basis functions allows for an accurate resolution of complex geometries and strong field gradients. In turn, this provides accurate results on the optical response of realistic structures. We study in detail the influence of particle size and shape on resonance frequencies as well as on scattering and absorption efficiencies. Beyond a critical size which determines the onset of the quasi-static limit we find significant deviations from the quasi-static theory. Furthermore, we investigate the influence of the excitation by comparing normal illumination and attenuated total internal reflection setups. Finally, we examine the possibility of coherently controlling the local field enhancement of V-structures via chirped pulses.

  8. 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

  9. Plasmonic nanostructured metal-oxide-semiconductor reflection modulators.

    PubMed

    Olivieri, Anthony; Chen, Chengkun; Hassan, Sa'ad; Lisicka-Skrzek, Ewa; Tait, R Niall; Berini, Pierre

    2015-04-08

    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.

  10. 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

    2015-05-04

    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%).

  11. Theory for self-consistent interplay between light and nanomaterials strongly modified by metallic nanostructures.

    PubMed

    Ishikawa, Akira; Osono, Katsuya; Nobuhiro, Atsushi; Mizumoto, Yoshihiko; Torimoto, Tsukasa; Ishihara, Hajime

    2013-03-28

    The design of the interplay between light and nanomaterials by the effect of localized-surface-plasmon resonance in metallic nanostructures is a fascinating subject, and recently, a lot of research has been carried out from both fundamental and applicational points of view. In this paper, we demonstrate the theories for describing the self-consistent interplay between the electronic states in the nanomaterials, the localized surface plasmons in the metallic nanostructures, and the light field, which provides insight into how the photoexcitation processes are modified through microscopic energy exchanges. As examples of such demonstrations, we show two cases, i.e., the interaction between a single metallic nanosphere and a quantum dot, and that between metallic nanostructures forming a nanogap and dimer molecules, where a peculiar dependence of photoexcitation processes on the distance between the metallic nanostructure and the absorbers arises depending on the respective characteristics of their interplay.

  12. Experimental Analysis of Nano-structures on Anode Metal Surfaces in Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Kovach, Yao; Foster, John

    2016-10-01

    Nano-structures were observed on the metal (tungsten, molybdenum) surface with helium plasma under fusion relevant plasma condition. It could bring serious problems for fusion reactors such as material erosion, dust formation and divertor lifetime etc. However, In order to solve these problems, further studies on topic of finding more unknown conditions of Nano-structure formation will be indispensable. This work focuses on the investigations of Nano-structures with its formation factors in atmospheric pressure. An electron microscopy is used to assess anode metal surface morphological changes. In particular, various Nano-structures are observed on both tungsten and stainless steel anode surfaces by the exposure to helium plasma. The characteristics of Nano-structures are documented in terms of type and size. Furthermore, material composition spectrum and mapping are used to define the status of extra growth and local area on anode metal surface with and without helium plasma effect.

  13. 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

  14. 3D graphene preparation via covalent amide functionalization for efficient metal-free electrocatalysis in oxygen reduction

    PubMed Central

    Ahmed, Mohammad Shamsuddin; Kim, Young-Bae

    2017-01-01

    3D and porous reduced graphene oxide (rGO) catalysts have been prepared with sp3-hybridized 1,4-diaminobutane (sp3-DABu, rGO-sp3-rGO) and sp2-hybridized 1,4-diaminobenzene (sp2-DABe, rGO-sp2-rGO) through a covalent amidation and have employed as a metal-free electrocatalyst for oxygen reduction reaction (ORR) in alkaline media. Both compounds have used as a junction between functionalized rGO layers to improve electrical conductivity and impart electrocatalytic activity to the ORR resulting from the interlayer charge transfer. The successful amidation and the subsequent reduction in the process of catalyst preparation have confirmed by X-ray photoelectron spectroscopy. A hierarchical porous structure is also confirmed by surface morphological analysis. Specific surface area and thermal stability have increased after successful the amidation by sp3-DABu. The investigated ORR mechanism reveals that both functionalized rGO is better ORR active than nonfunctionalized rGO due to pyridinic-like N content and rGO-sp3-rGO is better ORR active than rGO-sp2-rGO due to higher pyridinic-like N content and π-electron interaction-free interlayer charge transfer. Thus, the rGO-sp3-rGO has proven as an efficient metal-free electrocatalyst with better electrocatalytic activity, stability, and tolerance to the crossover effect than the commercially available Pt/C for ORR. PMID:28240302

  15. 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.

  16. Kβ/ Kα intensity ratios for X-ray production in 3d metals by gamma-rays and protons

    NASA Astrophysics Data System (ADS)

    Bhuinya, C. R.; Padhi, H. C.

    1994-04-01

    Systematic measurements of Kβ/ Kα intensity ratios for X-ray production in 3d metals have been carried out using γ-ray and fast proton ionization methods. The measured ratios from proton ionization experiments indicate production of multivacancies in the L shell giving rise to higher Kβ/ Kα ratios compared to the present γRF results and 2 MeV proton ionization results of Perujo et al. [Perujo A., Maxwell J. A., Teesdale W. J. and Cambell J. L. (1987) J. Phys. B: Atom. Molec. Phys.20, 4973]. This is consistent with the SCA model calculation which gives increased simultaneous K- and L-shell ionization at 4 MeV. The present results from γRF experiments are in close agreement with the 2 MeV proton ionization results of Perujo et al. (1987) and also with the theoretical calculation of jankowski and Polasik [Jankowski K. and Polasik M. (1989) J. Phys. B: Atom. Molec. Optic. Phys. 22, 2369] but the theoretical results of Scofield [Scofield J. H. (1974a) Atom. Data Nucl. Data Tables14, 12] are somewhat higher.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. Performance of density functional theory for 3d transition metal-containing complexes: utilization of the correlation consistent basis sets.

    PubMed

    Tekarli, Sammer M; Drummond, Michael L; Williams, T Gavin; Cundari, Thomas R; Wilson, Angela K

    2009-07-30

    The performance of 44 density functionals used in conjunction with the correlation consistent basis sets (cc-pVnZ where n = T and Q) has been assessed for the gas-phase enthalpies of formation at 298.15 K of 3d transition metal (TM) containing systems. Nineteen molecules were examined: ScS, VO, VO(2), Cr(CO)(6), MnS, MnCl(2), Mn(CO)(5)Cl, FeCl(3), Fe(CO)(5), CoH(CO)(4), NiCl(2), Ni(CO)(4), CuH, CuF, CuCl, ZnH, ZnO, ZnCl, and Zn(CH(3))(2). Of the functionals examined, the functionals that resulted in the smallest mean absolute deviation (MAD, in parentheses, kcal mol(-1)) from experiment were B97-1 (6.9), PBE1KCIS (8.1), TPSS1KCIS (9.6), B97-2 (9.7), and B98 (10.7). All five of these functionals include some degree of Hartree-Fock (HF) exchange. The impact of increasing the basis set from cc-pVTZ to cc-pVQZ was found to be slight for the generalized gradient approximation (GGA) and meta-GGA (MGGA) functionals studied, indicating basis set saturation at the triple-zeta level. By contrast, for most of the generalized gradient exchange (GGE), hybrid GGA (HGGA), and hybrid meta-GGA (HMGGA) functionals considered, improvements in the average MAD of 2-3 kcal mol(-1) were seen upon progressing to a quadruple-zeta level basis set. Overall, it was found that the functionals that include Hartree-Fock exchange performed best overall, but those with greater than 40% HF exchange exhibit significantly poor performance for the prediction of enthalpies of formation for 3d TM complexes. Carbonyl-containing complexes, a mainstay in organometallic TM chemistry, are demonstrated to be exceedingly difficult to describe accurately with all but 2 of the 44 functionals considered. The most accurate functional, for both CO-containing and CO-free compounds, is B97-1/cc-pVQZ, which is shown to be capable of yielding results within 1 kcal mol(-1) of high-level ab initio composite methodologies.

  2. 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.

  3. 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

  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. 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.

  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.

  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 [Albuquerque, NM; Tringe, Joseph W [Walnut Creek, CA; Vanamu, Ganesh [Sunnyvale, CA; Prinja, Rajiv [Albuquerque, NM

    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. Nanostructured Carbon Nitride Polymer-Reinforced Electrolyte To Enable Dendrite-Suppressed Lithium Metal Batteries.

    PubMed

    Hu, Jiulin; Tian, Jing; Li, Chilin

    2017-04-05

    Lithium metal batteries (LMBs) containing S, O2, and fluoride cathodes are attracting increasing attention owing to their much higher energy density than that of Li-ion batteries. However, current limitation for the progress of LMBs mainly comes from the uncontrolled formation and growth of Li dendrites at the anode side. In order to suppress dendrite growth, exploring novel nanostructured electrolyte of high modulus without degradation of Li-electrolyte interface appears to be a potential solution. Here we propose a lightweight polymer-reinforced electrolyte based on graphitic carbon nitride (g-C3N4) mesoporous microspheres as electrolyte filler [bis(trifluoromethanesulfonimide) lithium salt/di(ethylene glycol) dimethyl ether mixed with g-C3N4, denoted as LiTFSI-DGM-C3N4] for the first time. This nanostructured electrolyte can effectively suppress lithium dendrite growth during cycling, benefiting from the high mechanical strength and nanosheet-built hierarchical structure of g-C3N4. The Li/Li symmetrical cell based on this slurrylike electrolyte enables long-term cycling of at least 120 cycles with a high capacity of 6 mA·h/cm(2) and small plating/stripping overpotential of ∼100 mV at a high current density of 2 mA/cm(2). g-C3N4 filling also enables a separator(Celgard)-free Li/FeS2 cell with at least 400 cycles. The 3D geometry of g-C3N4 shows advantages on interfacial resistance and Li plating/stripping stability compared to its 2D geometry.

  10. The essential role of spin-memory loss at 3d/5d metallic interfaces in spin pumping

    NASA Astrophysics Data System (ADS)

    Jaffres, Henri

    2015-03-01

    I will present a review of experiments and theory of spin-pumping in Co/(Cu)/Pt 3d/5d metallic systems in the ferromagnetic resonance (FMR) regime of spin injection. By combining i) FMR analyses of the resonance linewidth of the Co spectra in contact with the Pt (or Cu/Pt) reservoir and ii) detection of the inverse spin-hall effect signal vs. Pt thickness, we were able to evidence two different lengthscales for the spin-current profile generated or absorbed at the interfaces. The first lenghscale, extracted from FMR analyses and of the order of 2 nm, represents a typical interface length characteristic of a spin memory loss at the Co/Pt and Co/Cu/Pt interfaces. This represent a typical region of spin-current dissipation by which almost 60-70 % of the total current generated is lost before conversion in bulk Pt. The second lengthscale, roughly equal to 3.4 nm, like determined by Inverse Spin Hall Effect (ISHE) transverse voltage measurement, is more characteristic of the spin-diffusion length of the bulk Pt that governs a part of the spin-to-charge conversion efficiency by ISHE. After careful analyses, we determined a spin-hall angle of 5.6 % for Pt and an intrinsic spin hall conductivity of 3200 (Ohm.cm)-1 for our corresponding Pt resistivity. In the end, I will focus on the physical description of our experiments within a derived Valet-Fert model describing the spin transport/relaxation in a diffusive approach and using relevant boundary conditions for spin-pumping (constant spin accumulation in the ferromagnet). The origin of the spin-memory loss and spin-current discontinuity, also proposed in a very recent work, will be explained in terms of atomic intermixing at interfaces or possible Rashba-split states at Co/Pt interfaces.

  11. A series of 3D metal organic frameworks based on [24-MC-6] metallacrown clusters: structure, magnetic and luminescence properties.

    PubMed

    Wang, Kai; Zou, Hua-Hong; Chen, Zi-Lu; Zhang, Zhong; Sun, Wei-Yin; Liang, Fu-Pei

    2014-09-14

    Four isostructural metal organic frameworks (MOFs), namely [Co6(HipO)6]·6H2O (1), [Mn6(HipO)6]·6H2O (2), [Cd6(HipO)6]·6H2O (3) and [Zn6(HipO)6]·7H2O (4) (H3ipO = 2-hydroxyisophthalic acid), were synthesized and structurally characterized. They have a 3D (4,6)-connected framework based on [24-MC-6] metallacrown clusters ([24-MC-6]-based MOFs). The arrangements of the 24-MC-6 metallacrown SBUs show a regular change indicated by the orientation of their symmetry axes, resulting in a special dense packing mode different from other [24-MC-6]-based MOFs. The analysis of SQUID measurements reveal that compound 1 displays the dominant antiferromagnetic exchanges in 300-10 K between the adjacent Co(II) ions and a ferromagnetic-like behavior at lower temperatures, whereas compound 2 shows an antiferromagnetic interaction between the adjacent Mn(II) ions. Compound 1 exhibits a magnetocaloric effect (MCE) with the resulting entropy change (-ΔS(m)) of 15.20 J kg(-1) K(-1) for ΔH = 50 kG at 6 K, which is the highest value among the cobalt-based MOFs with MCE reported so far. The luminescence properties of compounds 3 and 4 were studied, both of them exhibit photoluminescence in the solid state at room temperature which can be ascribed to intraligand π→π* transitions.

  12. Hybrid nanostructures of metal/two-dimensional nanomaterials for plasmon-enhanced applications.

    PubMed

    Li, Xuanhua; Zhu, Jinmeng; Wei, Bingqing

    2016-06-07

    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.

  13. Theoretical study of inverted sandwich type complexes of 4d transition metal elements: interesting similarities to and differences from 3d transition metal complexes.

    PubMed

    Kurokawa, Yusaku I; Nakao, Yoshihide; Sakaki, Shigeyoshi

    2012-03-08

    Inverted sandwich type complexes (ISTCs) of 4d metals, (μ-η(6):η(6)-C(6)H(6))[M(DDP)](2) (DDPH = 2-{(2,6-diisopropylphenyl)amino}-4-{(2,6-diisopropylphenyl)imino}pent-2-ene; M = Y, Zr, Nb, Mo, and Tc), were investigated with density functional theory (DFT) and MRMP2 methods, where a model ligand AIP (AIPH = (Z)-1-amino-3-imino-prop-1-ene) was mainly employed. When going to Nb (group V) from Y (group III) in the periodic table, the spin multiplicity of the ground state increases in the order singlet, triplet, and quintet for M = Y, Zr, and Nb, respectively, like 3d ISTCs reported recently. This is interpreted with orbital diagram and number of d electrons. However, the spin multiplicity decreases to either singlet or triplet in ISTC of Mo (group VI) and to triplet in ISTC of Tc (group VII), where MRMP2 method is employed because the DFT method is not useful here. These spin multiplicities are much lower than the septet of ISTC of Cr and the nonet of that of Mn. When going from 3d to 4d, the position providing the maximum spin multiplicity shifts to group V from group VII. These differences arise from the size of the 4d orbital. Because of the larger size of the 4d orbital, the energy splitting between two d(δ) orbitals of M(AIP) and that between the d(δ) and d(π) orbitals are larger in the 4d complex than in the 3d complex. Thus, when occupation on the d(δ) orbital starts, the low spin state becomes ground state, which occurs at group VI. Hence, the ISTC of Nb (group V) exhibits the maximum spin multiplicity.

  14. Study of heterogeneous catalysis by iron-squarate based 3D metal organic framework for the transformation of tetrazines to oxadiazole derivatives.

    PubMed

    Goswami, Soumyabrata; Jena, Himanshu Sekhar; Konar, Sanjit

    2014-07-21

    We present here a simple, milder, and environmentally benign heterogeneous catalytic method for the transformation of tetrazines to oxadiazole derivatives at room temperature (25 °C) using our earlier synthesized iron-squarate based 3D metal organic framework, [Fe3(OH)3(C4O4)(C4O4)0.5]n (FeSq-MOF).

  15. Landau damping of quantum plasmons in metal nanostructures

    DOE PAGES

    Li, Xiaoguang; Xiao, Di; Zhang, Zhenyu

    2013-02-06

    Using the random phase approximation with both real space and discrete electron–hole (e–h) pair basis sets, we study the broadening of surface plasmons in metal structures of reduced dimensionality, where Landau damping is the dominant dissipation channel and presents an intrinsic limitation to plasmonics technology. We show that for every prototypical class of systems considered, including zero-dimensional nanoshells, one-dimensional coaxial nanotubes and two-dimensional ultrathin films, Landau damping can be drastically tuned due to energy quantization of the individual electron levels and e–h pairs. Both the generic trend and oscillatory nature of the tunability are in stark contrast with the expectationsmore » of the semiclassical surface scattering picture. Our approach also allows to vividly depict the evolution of the plasmons from the quantum to the classical regime, and to elucidate the underlying physical origin of hybridization broadening of nearly degenerate plasmon modes. Lastly, these findings may serve as a guide in the future design of plasmonic nanostructures of desirable functionalities.« less

  16. Landau damping of quantum plasmons in metal nanostructures

    SciTech Connect

    Li, Xiaoguang; Xiao, Di; Zhang, Zhenyu

    2013-02-06

    Using the random phase approximation with both real space and discrete electron–hole (e–h) pair basis sets, we study the broadening of surface plasmons in metal structures of reduced dimensionality, where Landau damping is the dominant dissipation channel and presents an intrinsic limitation to plasmonics technology. We show that for every prototypical class of systems considered, including zero-dimensional nanoshells, one-dimensional coaxial nanotubes and two-dimensional ultrathin films, Landau damping can be drastically tuned due to energy quantization of the individual electron levels and e–h pairs. Both the generic trend and oscillatory nature of the tunability are in stark contrast with the expectations of the semiclassical surface scattering picture. Our approach also allows to vividly depict the evolution of the plasmons from the quantum to the classical regime, and to elucidate the underlying physical origin of hybridization broadening of nearly degenerate plasmon modes. Lastly, these findings may serve as a guide in the future design of plasmonic nanostructures of desirable functionalities.

  17. 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

  18. Multispectral 3D phase-encoded turbo spin-echo for imaging near metal: Limitations and possibilities demonstrated by simulations and phantom experiments.

    PubMed

    van Gorp, Jetse S; Nizak, Razmara; Bouwman, Job G; Saris, Daniël B F; Seevinck, Peter R

    2017-01-25

    To see improvements in the imaging performance near biomaterial implants we assessed a multispectral fully phase-encoded turbo spin-echo (ms3D-PE-TSE) sequence for artifact reduction capabilities and scan time efficiency in simulation and phantom experiments. For this purpose, ms3D-PE-TSE and ms3D-TSE sequences were implemented to obtain multispectral images (±20kHz) of a cobalt-chromium (CoCr) knee implant embedded in agarose. In addition, a knee implant computer model and the acquired ms3D-PE-TSE images were used to investigate the possibilities for scan time acceleration using field-of-view (FOV) reduction for off-resonance frequency bins and compressed sensing reconstructions of undersampled data. Both acceleration methods were combined to acquire a +10kHz frequency bin in a second experiment. The obtained ms3D-PE-TSE images showed no susceptibility related artifacts, while ms3D-TSE images suffered from hyper-intensity artifacts. The limitations of ms3D-TSE were apparent in the far off-resonance regions (±[10-20]kHz) located close to the implant. The scan time calculations showed that ms3D-PE-TSE can be applied in a clinically relevant timeframe (~12min), when omitting the three central frequency bins. The feasibility of CS acceleration for ms3D-PE-TSE was demonstrated using retrospective reconstructions before combining CS and rFOV imaging to decrease the scan time for the +10kHz frequency bin from ~10.9min to ~3.5min, while also increasing the spatial resolution fourfold. The temporally resolved signal of ms3D-PE-TSE proved to be useful to decrease the intensity ripples after sum-of-squares reconstructions and increase the signal-to-noise ratio. The presented results suggest that the scan time limitations of ms3D-PE-TSE can be sufficiently addressed when focusing on signal acquisitions in the direct vicinity of metal implants. Because these regions cannot be measured with existing multispectral methods, the presented ms3D-PE-TSE method may enable the

  19. 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.

    2016-12-01

    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.

  20. Thermo-mechanical Characterization of Metal/Polymer Composite Filaments and Printing Parameter Study for Fused Deposition Modeling in the 3D Printing Process

    NASA Astrophysics Data System (ADS)

    Hwang, Seyeon; Reyes, Edgar I.; Moon, Kyoung-sik; Rumpf, Raymond C.; Kim, Nam Soo

    2015-03-01

    New metal/polymer composite filaments for fused deposition modeling (FDM) processes were developed in order to observe the thermo-mechanical properties of the new filaments. The acrylonitrile butadiene styrene (ABS) thermoplastic was mixed with copper and iron particles. The percent loading of the metal powder was varied to confirm the effects of metal particles on the thermo-mechanical properties of the filament, such as tensile strength and thermal conductivity. The printing parameters such as temperature and fill density were also varied to see the effects of the parameters on the tensile strength of the final product which was made with the FDM process. As a result of this study, it was confirmed that the tensile strength of the composites is decreased by increasing the loading of metal particles. Additionally, the thermal conductivity of the metal/polymer composite filament was improved by increasing the metal content. It is believed that the metal/polymer filament could be used to print metal and large-scale 3-dimensional (3D) structures without any distortion by the thermal expansion of thermoplastics. The material could also be used in 3D printed circuits and electromagnetic structures for shielding and other applications.

  1. 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

  2. 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.

  3. 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

  4. Suppression of infrared absorption in nanostructured metals by controlling Faraday inductance and electron path length.

    PubMed

    Han, Sang Eon

    2016-02-08

    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.

  5. 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.

  6. About mechanisms of radiation-induced effect of nanostructurization of near-surface volumes of metals

    NASA Astrophysics Data System (ADS)

    Ivchenko, V. A.

    2017-01-01

    Mechanisms of the radiation-induced development of nanostructures in subsurface metal regions have been analyzed based on field-ion microscopy data. It is concluded that the modification of near-surface metal regions on a nanometer scale as a result of the interaction with Ar+ ion beams proceeds by several mechanisms. In particular, for a fluence of F = 1016 ion/cm2 (at an ion energy of E = 30 keV), the main contribution is due to the ion channeling. A tenfold increase in the ion fluence leads to prevailing deformation mechanism in nanostructure formation in the subsurface metal regions.

  7. Quantitative moment study and coupling of 4 f rare earth and 3 d metal by transmitted electrons

    NASA Astrophysics Data System (ADS)

    Fu, X.; Warot-Fonrose, B.; Arras, R.; Dumesnil, K.; Serin, V.

    2016-10-01

    We report a simultaneous investigation of 3 d and 4 f magnetic moments by exploring the Fe -L2 ,3 and Dy -M4 ,5 electron energy-loss edges of a DyF e2/YF e2 superlattice using the energy-loss magnetic chiral dichroism (EMCD) technique. Specific EMCD sum rules for M4 ,5 edges were established and carefully applied to the dichroic signal at Dy -M4 ,5 edges, giving an orbital to the effective spin moment ratio of 5.1 ±1.8 . With dynamic diffraction effects considered, the opposite signs of Fe -L3 and Dy -M5 dichroic peaks unambiguously indicate the antiparallel alignment of net Fe 3 d and Dy 4 f moments. The EMCD technique is shown to be an effective tool to locally characterize the 4 f moment of rare earth elements and study 3 d -4 f moment coupling.

  8. Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy.

    PubMed

    Linic, Suljo; Christopher, Phillip; Ingram, David B

    2011-11-23

    Recent years have seen a renewed interest in the harvesting and conversion of solar energy. Among various technologies, the direct conversion of solar to chemical energy using photocatalysts has received significant attention. Although heterogeneous photocatalysts are almost exclusively semiconductors, it has been demonstrated recently that plasmonic nanostructures of noble metals (mainly silver and gold) also show significant promise. Here we review recent progress in using plasmonic metallic nanostructures in the field of photocatalysis. We focus on plasmon-enhanced water splitting on composite photocatalysts containing semiconductor and plasmonic-metal building blocks, and recently reported plasmon-mediated photocatalytic reactions on plasmonic nanostructures of noble metals. We also discuss the areas where major advancements are needed to move the field of plasmon-mediated photocatalysis forward.

  9. Magnetic domain configurations and huge wall resistivity in half-metallic chromium dioxide nanostructures

    NASA Astrophysics Data System (ADS)

    Zou, Xiaojing

    -wall-resistance (DWR) is determined to be three orders of magnitude larger than that of conventional 3d ferromagnets, as a result of the material's half-metallicity. We have measured DWR and the spin-torque effect along different crystallographic axes and at varying temperatures. Finally, we present the results of a theoretical analysis of this system, based on its half-metallic character and on the intrinsic magnetic behavior of CrO2.

  10. Complex-Morphology Metal-Based Nanostructures: Fabrication, Characterization, and Applications

    PubMed Central

    Gentile, Antonella; Ruffino, Francesco; Grimaldi, Maria Grazia

    2016-01-01

    Due to their peculiar qualities, metal-based nanostructures have been extensively used in applications such as catalysis, electronics, photography, and information storage, among others. New applications for metals in areas such as photonics, sensing, imaging, and medicine are also being developed. Significantly, most of these applications require the use of metals in the form of nanostructures with specific controlled properties. The properties of nanoscale metals are determined by a set of physical parameters that include size, shape, composition, and structure. In recent years, many research fields have focused on the synthesis of nanoscale-sized metallic materials with complex shape and composition in order to optimize the optical and electrical response of devices containing metallic nanostructures. The present paper aims to overview the most recent results—in terms of fabrication methodologies, characterization of the physico-chemical properties and applications—of complex-morphology metal-based nanostructures. The paper strongly focuses on the correlation between the complex morphology and the structures’ properties, showing how the morphological complexity (and its nanoscale control) can often give access to a wide range of innovative properties exploitable for innovative functional device production. We begin with an overview of the basic concepts on the correlation between structural and optical parameters of nanoscale metallic materials with complex shape and composition, and the possible solutions offered by nanotechnology in a large range of applications (catalysis, electronics, photonics, sensing). The aim is to assess the state of the art, and then show the innovative contributions that can be proposed in this research field. We subsequently report on innovative, versatile and low-cost synthesis techniques, suitable for providing a good control on the size, surface density, composition and geometry of the metallic nanostructures. The main

  11. Manipulating the Interfacial Electrical and Optical Properties of Dissimilar Materials with Metallic Nanostructures

    DTIC Science & Technology

    2016-07-30

    optical, structural , and chemically-sensitive techniques. We also examined the optical quality of III-V layers grown above ErAs nanostructures, which... structures . These findings led us to invent a technique to grow GaAs that is free of planar 15. SUBJECT TERMS Molecular Beam Epitaxy, Nanostructures...heterogeneous semiconductor device structure . Metal/semiconductor interfaces are, perhaps, the most fundamental building block of solid-state devices

  12. Room-Temperature Chemical Welding and Sintering of Metallic Nanostructures by Capillary Condensation.

    PubMed

    Yoon, Sung-Soo; Khang, Dahl-Young

    2016-06-08

    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.

  13. Decoration of Micro-/Nanoscale Noble Metal Particles on 3D Porous Nickel Using Electrodeposition Technique as Electrocatalyst for Hydrogen Evolution Reaction in Alkaline Electrolyte.

    PubMed

    Qian, Xin; Hang, Tao; Shanmugam, Sangaraju; Li, Ming

    2015-07-29

    Micro-/nanoscale noble metal (Ag, Au, and Pt) particle-decorated 3D porous nickel electrodes for hydrogen evolution reaction (HER) in alkaline electrolyte are fabricated via galvanostatic electrodeposition technique. The developed electrodes are characterized by field emission scanning electron microscopy and electrochemical measurements including Tafel polarization curves, cyclic voltammetry, and electrochemical impedance spectroscopy. It is clearly shown that the enlarged real surface area caused by 3D highly porous dendritic structure has greatly reinforced the electrocatalytic activity toward HER. Comparative analysis of electrodeposited Ag, Au, and Pt particle-decorated porous nickel electrodes for HER indicates that both intrinsic property and size of the noble metal particles can lead to distinct catalytic activities. Both nanoscale Au and Pt particles have further reinforcement effect toward HER, whereas microscale Ag particles exhibit the reverse effect. As an effective 3D hydrogen evolution cathode, the nanoscale Pt-particle-decorated 3D porous nickel electrode demonstrates the highest catalytic activity with an extremely low overpotential of -0.045 V for hydrogen production, a considerable exchange current density of 9.47 mA cm(-2) at 25 °C, and high durability in long-term electrolysis, all of which are attributed to the intrinsic catalytic property and the extremely small size of Pt particles.

  14. Hollow metal nanostructures for enhanced plasmonics: synthesis, local plasmonic properties and applications

    NASA Astrophysics Data System (ADS)

    Genç, Aziz; Patarroyo, Javier; Sancho-Parramon, Jordi; Bastús, Neus G.; Puntes, Victor; Arbiol, Jordi

    2016-09-01

    Metallic nanostructures have received great attention due to their ability to generate surface plasmon resonances, which are collective oscillations of conduction electrons of a material excited by an electromagnetic wave. Plasmonic metal nanostructures are able to localize and manipulate the light at the nanoscale and, therefore, are attractive building blocks for various emerging applications. In particular, hollow nanostructures are promising plasmonic materials as cavities are known to have better plasmonic properties than their solid counterparts thanks to the plasmon hybridization mechanism. The hybridization of the plasmons results in the enhancement of the plasmon fields along with more homogeneous distribution as well as the reduction of localized surface plasmon resonance (LSPR) quenching due to absorption. In this review, we summarize the efforts on the synthesis of hollow metal nanostructures with an emphasis on the galvanic replacement reaction. In the second part of this review, we discuss the advancements on the characterization of plasmonic properties of hollow nanostructures, covering the single nanoparticle experiments, nanoscale characterization via electron energy-loss spectroscopy and modeling and simulation studies. Examples of the applications, i.e. sensing, surface enhanced Raman spectroscopy, photothermal ablation therapy of cancer, drug delivery or catalysis among others, where hollow nanostructures perform better than their solid counterparts, are also evaluated.

  15. Hollow metal nanostructures for enhanced plasmonics: synthesis, local plasmonic properties and applications

    NASA Astrophysics Data System (ADS)

    Genç, Aziz; Patarroyo, Javier; Sancho-Parramon, Jordi; Bastús, Neus G.; Puntes, Victor; Arbiol, Jordi

    2017-01-01

    Metallic nanostructures have received great attention due to their ability to generate surface plasmon resonances, which are collective oscillations of conduction electrons of a material excited by an electromagnetic wave. Plasmonic metal nanostructures are able to localize and manipulate the light at the nanoscale and, therefore, are attractive building blocks for various emerging applications. In particular, hollow nanostructures are promising plasmonic materials as cavities are known to have better plasmonic properties than their solid counterparts thanks to the plasmon hybridization mechanism. The hybridization of the plasmons results in the enhancement of the plasmon fields along with more homogeneous distribution as well as the reduction of localized surface plasmon resonance (LSPR) quenching due to absorption. In this review, we summarize the efforts on the synthesis of hollow metal nanostructures with an emphasis on the galvanic replacement reaction. In the second part of this review, we discuss the advancements on the characterization of plasmonic properties of hollow nanostructures, covering the single nanoparticle experiments, nanoscale characterization via electron energy-loss spectroscopy and modeling and simulation studies. Examples of the applications, i.e. sensing, surface enhanced Raman spectroscopy, photothermal ablation therapy of cancer, drug delivery or catalysis among others, where hollow nanostructures perform better than their solid counterparts, are also evaluated.

  16. 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.

  17. 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.

  18. The change of the LMM auger spectra in 3d-metals due to oxidation and its correlation with the change of the atomic magnetic moment.

    PubMed

    Zheltysheva, Olga R; Surnin, Dmitry V; Guy, Dmitry E; Gil'mutdinov, Faat Z; Ruts, Yuri V; Grebennikov, Vladimir I

    2005-12-01

    The surfaces of crystalline samples of 3d-metals (Mn, Fe, Co, Ni, and Cu) and their stoichiometric oxides have been studied by Auger spectroscopy. A correlation between the change in the LVV (L-inner level-valence-valence electron transition) Auger intensities and the change of the squares of the corresponding atomic-magnetic moments has been observed. This is because of the complicated nature of the Auger process. That is, the Auger electron emission is a result of the inner atomic level excitation by electron impact and Auger annihilation of the inner-level hole. Therefore, the Auger process has been considered a second-order process, and spin polarization of the valence states has been taken into account for the LMM (L-inner level-M-inner level-M-inner level electron transition) Auger spectra of 3d-metals.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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.

  4. Use of L-edge X-ray absorption spectroscopy to characterize multiple valence states of 3 d transition metals; a new probe for mineralogical and geochemical research

    NASA Astrophysics Data System (ADS)

    Cressey, G.; Henderson, C. M. B.; van der Laan, G.

    1993-07-01

    2 p ( L 2,3) X-ray absorption spectra are presented for a range of minerals to demonstrate the usefulness of L-edge spectroscopy as a symmetry- and valenceselective probe. 2 p XAS provides a sensitive fingerprint of the electronic states of 3 d transition metals and can be applied to phases containing mixtures of such elements. Calculated spectra for 3 d n → 2 p 5 3 d n+1 transitions provide a basis for the interpretation of the measured spectra. Thus, in principle, multiple valence states of a particular 3 d metal can be precisely characterized from a single L-edge spectrum. Examples of vanadium L-edge spectra are presented for a range of minerals; these complex spectra hold information concerning the presence of vanadium in multiple valence states. The Cu L-edge spectrum of sulvanite (Cu3 VS4) indicates the presence of both Cu+ and Cu2+; the V L-edge spectrum of the same sample shows that both V2+ and V5+ are present. Spectral simulations representing mixtures of Fe d 5 and Fe d 6 states are used to quantify Fe3+/ ∑Fe in a spinel, a glass, and an amphibole, all of which contain Fe as a major component. To illustrate the sensitivity of 2 p XAS in a dilute system, the Fe L-edge spectrum of amethyst ( α-SiO2: Fe) has been recorded; this spectrum shows that ˜68% of the Fe in amethyst is Fe2+, and ˜32% is Fe3+. Although previous studies on amethyst using other spectroscopic methods cite evidence for Fe4+, there is no indication in the L-edge spectrum for Fe4+ in amethyst. Comparison of theoretical and experimental spectra not only allows the valence states of 3 d ions to be recognised, but also provides site-symmetry information and crystal field parameters for each ion site.

  5. Kagome-type isostructural 3D-transition metal fluorosulfates with spin 3/2 and 1: synthesis, structure and characterization.

    PubMed

    Marri, Subba R; Kumar, Jitendra; Panyarat, Kitt; Horike, Satoshi; Behera, J N

    2016-11-28

    Two isostructural transition metal fluorosulfates based on Co and Ni metal ions with the molecular composition of [H3O][M(SO4)F] (where M = Co((II)) for 1 and Ni((II)) for 2) were synthesized under solvothermal conditions and structurally characterized by single crystal X-ray analysis. The materials were further characterized by complementary techniques like TGA, FTIR and PXRD. The 3D-crystal lattice consists of a kagome-type entity where sulfate groups replaced one of the metal nodes when compared with true kagome structures. Magnetic studies of the complexes were also performed which showed that the interactions at the metal center are antiferromagnetic in nature. The proton conductivity increases with the increase in humidity and was found to be 7.9 × 10(-6) S cm(-1) for 2 at RH = 98%.

  6. 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

  7. Nanostructural self-organization and dynamic adaptation of metal-polymer tribosystems

    NASA Astrophysics Data System (ADS)

    Mashkov, Yu. K.

    2017-02-01

    The results of investigating the effect of nanosize modifiers of a polymer matrix on the nanostructural self-organization of polymer composites and dynamic adaptation of metal-polymer tribosystems, which considerably affect the wear resistance of polymer composite materials, have been analyzed. It has been shown that the physicochemical nanostructural self-organization processes are developed in metal-polymer tribosystems with the formation of thermotropic liquid-crystal structures of the polymer matrix, followed by the transition of the system to the stationary state with a negative feedback that ensures dynamic adaptation of the tribosystem to given operating conditions.

  8. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

    SciTech Connect

    Hegde, Ganesh Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard; Boykin, Timothy

    2014-03-28

    Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

  9. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

    NASA Astrophysics Data System (ADS)

    Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

    2014-03-01

    Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

  10. Chemical Control of Plasmons in Metal Chalcogenide and Metal Oxide Nanostructures.

    PubMed

    Mattox, Tracy M; Ye, Xingchen; Manthiram, Karthish; Schuck, P James; Alivisatos, A Paul; Urban, Jeffrey J

    2015-10-14

    The field of plasmonics has grown to impact a diverse set of scientific disciplines ranging from quantum optics and photovoltaics to metamaterials and medicine. Plasmonics research has traditionally focused on noble metals; however, any material with a sufficiently high carrier density can support surface plasmon modes. Recently, researchers have made great gains in the synthetic (both intrinsic and extrinsic) control over the morphology and doping of nanoscale oxides, pnictides, sulfides, and selenides. These synthetic advances have, collectively, blossomed into a new, emerging class of plasmonic metal chalcogenides that complement traditional metallic materials. Chalcogenide and oxide nanostructures expand plasmonic properties into new spectral domains and also provide a rich suite of chemical controls available to manipulate plasmons, such as particle doping, shape, and composition. New opportunities in plasmonic chalcogenide nanomaterials are highlighted in this article, showing how they may be used to fundamentally tune the interaction and localization of electromagnetic fields on semiconductor surfaces in a way that enables new horizons in basic research and energy-relevant applications.

  11. Designing deoxidation inhibiting encapsulation of metal oxide nanostructures for fluidic and biological applications

    NASA Astrophysics Data System (ADS)

    Ghosh, Moumita; Ghosh, Siddharth; Seibt, Michael; Schaap, Iwan A. T.; Schmidt, Christoph F.; Mohan Rao, G.

    2016-12-01

    Due to their photoluminescence, metal oxide nanostructures such as ZnO nanostructures are promising candidates in biomedical imaging, drug delivery and bio-sensing. To apply them as label for bio-imaging, it is important to study their structural stability in a bio-fluidic environment. We have explored the effect of water, the main constituent of biological solutions, on ZnO nanostructures with scanning electron microscopy (SEM) and photoluminescence (PL) studies which show ZnO nanorod degeneration in water. In addition, we propose and investigate a robust and inexpensive method to encapsulate these nanostructures (without structural degradation) using bio-compatible non-ionic surfactant in non-aqueous medium, which was not reported earlier. This new finding is an immediate interest to the broad audience of researchers working in biophysics, sensing and actuation, drug delivery, food and cosmetics technology, etc.

  12. Metal-enhanced intrinsic fluorescence of nucleic acids using platinum nanostructured substrates

    PubMed Central

    Akbay, Nuriye; Mahdavi, Farhad; Lakowicz, Joseph R.; Ray, Krishanu

    2012-01-01

    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. PMID:23002289

  13. 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.

  14. New metal catalyzed syntheses of nanostructured boron nitride and alkenyldecaboranes

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shahana

    The goals of the research described in this dissertation were two-fold. The first goal was to develop new methods, employing metal-catalyzed chemical vapor deposition reactions of molecular polyborane precursors, for the production of boron nitride nanostructured materials, including both boron nitride nanotubes (BNNTs) and boron nitride nanosheets (BNNS). The second goal was to develop new systematic metal-catalyzed reactions for polyboranes that would facilitate their functionalization for possible biomedical and/or materials applications. The syntheses of multi- and double-walled BNNTs were achieved with the aid of a floating nickel catalyst via the catalytic chemical vapor deposition (CCVD) of borazine (B3N3H6) or decaborane (B10H14) molecular precursors in ammonia atmospheres, with each precursor having its own advantages. While borazine is a single-source precursor containing both boron and nitrogen, the decaborane-based syntheses required the additional step of reaction with ammonia. However, the higher observed BNNT yields and the ease of handling and commercial availability of decaborane are distinct advantages. The BNNTs derived from both precursors were crystalline with highly ordered structures. The BNNTs grown at 1200 ºC from borazine were mainly double walled, with lengths up to 0.2 µm and ˜2 nm diameters. The BNNTs grown at 1200-1300 ºC from decaborane were double- and multi-walled, with the double-walled nanotubes having ˜2 nm inner diameters and the multi-walled nanotubes (˜10 walls) having ˜4-5 nm inner diameters and ˜12-14 nm outer diameters. BNNTs grown from decaborane at 1300 ºC were longer, averaging ˜0.6 µm, whereas those grown at 1200 ºC had average lengths of ˜0.2 µm. The BNNTs were characterized using scanning and transmission electron microscopies (SEM and TEM), and electron energy loss spectroscopy (EELS). This floating catalyst method now provides a catalytic and potentially scalable route to BNNTs with low defect density

  15. 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.

  16. Image detection of inner wall surface of holes in metal sheets through polarization using a 3D TV monitor

    NASA Astrophysics Data System (ADS)

    Suzuki, Takamasa; Nakano, Katsunori; Muramatsu, Shogo; Oitate, Toshiro

    2012-11-01

    We propose an effective technique for optically detecting images of the inner hole-surface of a hole (hereafter, referred to as the hole-surface) using the polarization property of a 3D television (TV) monitor. The polarized light emitted by the TV monitor illuminates the hole-surfaces present in the test target placed on the screen of the monitor. When the polarizer placed in front of a camera lens is adjusted such that the camera captures a dark image for the transmitted light, only the highlighted hole-surfaces are visible in the captured image.

  17. 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.

  18. 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.

  19. Charge transport across high surface area metal/diamond nanostructured composites.

    PubMed

    Plana, D; Humphrey, J J L; Bradley, K A; Celorrio, V; Fermín, D J

    2013-04-24

    High surface area composites featuring metal nanostructures and diamond particles have generated a lot of interest in the fields of heterogeneous catalysis, electrocatalysis, and sensors. Diamond surfaces provide a chemically robust framework for active nanostructures in comparison with sp(2) carbon supports. The present paper investigates the charge transport properties of high surface area films of high-pressure, high-temperature diamond particles in the presence and absence of metal nanostructures, employing electrochemical field-effect transistors. Oxygen- and hydrogen-terminated surfaces were generated on 500 nm diamond powders. Homogeneously distributed metal nanostructures, with metal volume fractions between ca. 5 and 20%, were either nucleated at the diamond particles by impregnation or incorporated from colloidal solution. Electrochemical field-effect transistor measurements, employing interdigitated electrodes, allowed the determination of composite conductivity as a function of electrode potential, as well as in air. In the absence of metal nanostructures, the lateral conductivity of the diamond assemblies in air is increased by over one order of magnitude upon hydrogenation of the particle surface. This observation is consistent with studies at diamond single crystals, although the somewhat modest change in conductivity suggests that charge transport is not only determined by the intrinsic surface conductivity of individual diamond particles but also by particle-to-particle charge transfer. Interestingly, the latter contribution effectively controls the assembly conductivity in the presence of an electrolyte solution as the difference between hydrogenated and oxygenated particles vanishes. The conductivity in the presence of metal nanoparticles is mainly determined by the metal volume fraction, while diamond surface termination and the presence of electrolyte solutions exert only minor effects. The experimental trends are discussed in terms of the

  20. Nanopatterning the electronic properties of gold surfaces with self-organized superlattices of metallic nanostructures.

    PubMed

    Didiot, Clement; Pons, Stephane; Kierren, Bertrand; Fagot-Revurat, Yannick; Malterre, Daniel

    2007-10-01

    The self-organized growth of nanostructures on surfaces could offer many advantages in the development of new catalysts, electronic devices and magnetic data-storage media. The local density of electronic states on the surface at the relevant energy scale strongly influences chemical reactivity, as does the shape of the nanoparticles. The electronic properties of surfaces also influence the growth and decay of nanostructures such as dimers, chains and superlattices of atoms or noble metal islands. Controlling these properties on length scales shorter than the diffusion lengths of the electrons and spins (some tens of nanometres for metals) is a major goal in electronics and spintronics. However, to date, there have been few studies of the electronic properties of self-organized nanostructures. Here we report the self-organized growth of macroscopic superlattices of Ag or Cu nanostructures on Au vicinal surfaces, and demonstrate that the electronic properties of these systems depend on the balance between the confinement and the perturbation of the surface states caused by the steps and the nanostructures' superlattice. We also show that the local density of states can be modified in a controlled way by adjusting simple parameters such as the type of metal deposited and the degree of coverage.

  1. Formation of nanostructures under femtosecond laser ablation of metals

    SciTech Connect

    Ashitkov, S I; Romashevskii, S A; Komarov, P S; Burmistrov, A A; Agranat, M B; Zhakhovskii, V V; Inogamov, N A

    2015-06-30

    We present the results of studying the morphology of the modified surface of aluminium, nickel and tantalum after ablation of the surface layer by a femtosecond laser pulse. The sizes of characteristic elements of a cellular nanostructure are found to correlate with thermo-physical properties of the material and the intensity of laser radiation. (superstrong light fields)

  2. 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.

  3. Unusual Transformation from a Solvent-Stabilized 1D Coordination Polymer to a Metal-Organic Framework (MOF)-Like Cross-Linked 3D Coordination Polymer.

    PubMed

    Lee, Seung-Chul; Choi, Eun-Young; Lee, Sang-Beom; Kim, Sang-Wook; Kwon, O-Pil

    2015-10-26

    An unusual 1D-to-3D transformation of a coordination polymer based on organic linkers containing highly polar push-pull π-conjugated side chains is reported. The coordination polymers are synthesized from zinc nitrate and an organic linker, namely, 2,5-bis{4-[1-(4-nitrophenyl)pyrrolidin-2-yl]butoxy}terephthalic acid, which possesses highly polar (4-nitrophenyl)pyrrolidine groups, with high dipole moments of about 7 D. The coordination polymers exhibit an unusual transformation from a soluble, solvent-stabilized 1D coordination polymer into an insoluble, metal-organic framework (MOF)-like 3D coordination polymer. The coordination polymer exhibits good film-forming ability, and the MOF-like films are insoluble in conventional organic solvents.

  4. Optical Properties of Self-Ensemble Monolayers of Gold Metallic Nanostructures

    NASA Astrophysics Data System (ADS)

    Macuil, R. Delgado; Gayou, V. López; López, M. Rojas; Contreras, R. Molina; Servin, J. L. Garcí; Ramírez, J. F. Sánchez

    2008-04-01

    This work analyzes the optical properties of nanostructures metallic surfaces of gold, at different sizes, in glass silanized substrates. Silanized substrates were immersed in the colloid solution for one and half hour at room temperature and dried at room temperature for four hours. The optical properties were analyzed by three spectroscopy techniques and by TEM microscopy. UV/VIS was used to observe changes in absorption due to the aminopropiltrimethoxysilane added to the glass substrate and due to the colloid added to silanized substrate. Infrared vibrational spectroscopy in ATR mode was used to observe the new generation peaks due to substrate silanization and SEIRA effect due to the colloid added to silanized substrate. And finally Z-Scan technique was used to observe the nonlinear properties of these funtionalization metallic nanostructures in function of nanostructures size. TEM images confirm the sizes observed in the UV/VIS spectra.

  5. Catalysts of self-assembled Pt@CeO2-δ-rich core-shell nanoparticles on 3D ordered macroporous Ce1-xZrxO2 for soot oxidation: nanostructure-dependent catalytic activity.

    PubMed

    Wei, Yuechang; Jiao, Jinqing; Zhang, Xindong; Jin, Baofang; Zhao, Zhen; Xiong, Jing; Li, Yazhao; Liu, Jian; Li, Jianmei

    2017-03-30

    The catalytic performance in heterogeneous catalytic reactions consisting of solid reactants is strongly dependent on the nanostructure of the catalysts. Metal-oxides core-shell (MOCS) nanostructures have potential to enhance the catalytic activity for soot oxidation reactions as a result of optimizing the density of active sites located at the metal-oxide interface. Here, we report a facile strategy for fabricating nanocatalysts with self-assembled Pt@CeO2-δ-rich core-shell nanoparticles (NPs) supported on three-dimensionally ordered macroporous (3DOM) Ce1-xZrxO2via the in situ colloidal crystal template (CCT) method. The nanostructure-dependent activity of the catalysts for soot oxidation were investigated by means of SEM, TEM, H2-TPR, XPS, O2-isothermal chemisorption, soot-TPO and so on. A CeO2-δ-rich shell on a Pt core is preferentially separated from Ce1-xZrxO2 precursors and could self-assemble to form MOCS nanostructures. 3DOM structures can enhance the contact efficiency between catalysts and solid reactants (soot). Pt@CeO2-δ-rich core-shell nanostructures can optimize the density of oxygen vacancies (Ov) as active sites located at the interface of Pt-Ce1-xZrxO2. Remarkably, 3DOM Pt@CeO2-δ-rich/Ce1-xZrxO2 catalysts show super catalytic performance and strongly nanostructure-dependent activity for soot oxidation in the absence of NO and NO2. For example, the T50 of the 3DOM Pt@CeO2-δ-rich/Ce0.8Zr0.2O2 catalyst is lowered down to 408 °C, and the reaction rate of the 3DOM Pt@CeO2-δ-rich/Ce0.2Zr0.8O2 catalyst (0.12 μmol g(-1) s(-1)) at 300 °C is 4 times that of the 3DOM Pt/Ce0.2Zr0.8O2 catalyst (0.03 μmol g(-1) s(-1)). The structures of 3DOM Ce1-xZrxO2-supported Pt@CeO2-δ-rich core-shell NPs are decent systems for deep oxidation of solid reactants or macromolecules, and this facile technique for synthesizing catalysts has potential to be applied to other element compositions.

  6. Hybrid nickel manganese oxide nanosheet-3D metallic dendrite percolation network electrodes for high-rate electrochemical energy storage.

    PubMed

    Nguyen, Tuyen; Eugénio, Sónia; Boudard, Michel; Rapenne, Laetitia; Carmezim, M João; Silva, Teresa M; Montemor, M Fátima

    2015-08-07

    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.

  7. 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

    2017-02-01

    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.

  8. 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

  9. Nanostructured carbon-metal oxide composite electrodes for supercapacitors: a review.

    PubMed

    Zhi, Mingjia; Xiang, Chengcheng; Li, Jiangtian; Li, Ming; Wu, Nianqiang

    2013-01-07

    This paper presents a review of the research progress in the carbon-metal oxide composites for supercapacitor electrodes. In the past decade, various carbon-metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon-metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.

  10. 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.

  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. 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.

  13. 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,...

  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.

  15. Formation of heteroepitaxy in different shapes of Au-CdSe metal-semiconductor hybrid nanostructures.

    PubMed

    Haldar, Krishna Kanta; Pradhan, Narayan; Patra, Amitava

    2013-10-25

    Formation of heteroepitaxy and designing different-shaped heterostructured nanomaterials of metal and semiconductor in solution remains a frontier area of research. However, it is evident that the synthesis of such materials is not straightforward and needs a selective approach to retain both metal and semiconductor identities in the reaction system during heterostructure formation. Herein, the epitaxial growth of semiconductor CdSe on selected facets of metal Au seeds is reported and different shapes (flower, tetrapod, and core/shell) hetero-nanostructures are designed. These results are achieved by controlling the reaction parameters, and by changing the sequence and timing for introduction of different reactant precursors. Direct evidence of the formation of heteroepitaxy between {111} facets of Au and (0001) of wurtzite CdSe is observed during the formation of these three heterostructures. The mechanism of the evolution of these hetero-nanostructures and formation of their heteroepitaxy with the planes having minimum lattice mismatch are also discussed. This shape-control growth mechanism in hetero-nanostructures should be helpful to provide more information for establishing the fundamental study of heteroepitaxial growth for designing new nanomaterials. Such metal-semiconductor nanostructures may have great potential for nonlinear optical properties, in photovoltaic devices, and as chemical sensors.

  16. 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

  17. Guided evolution of bulk metallic glass nanostructures: A platform for designing three-dimensional electrocatalytic surfaces

    SciTech Connect

    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; Schroers, Jan; Mukherjee, Sundeep; Taylor, Andre D.

    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.

  18. 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.

  19. Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response

    NASA Astrophysics Data System (ADS)

    Kajita, Shin; Yoshida, Tomoko; Kitaoka, Daiki; Etoh, Reo; Yajima, Miyuki; Ohno, Noriyasu; Yoshida, Hisao; Yoshida, Naoaki; Terao, Yoshitaka

    2013-04-01

    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.

  20. 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

  1. 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

  2. Nanoimprint-assisted directed self-assembly of low-molecular weight block copolymers: a route for 3D and multilevel nanostructures

    NASA Astrophysics Data System (ADS)

    Simão, C.; Khunsin, W.; Kehagias, N.; Francone, A.; Zelsmann, M.; Morris, M. A.; Sotomayor Torres, C. M.

    2014-06-01

    Multilevel controllable nanoimprint driven molecular orientation has been obtained in thin films of block copolymer polystyrene-b-polyethylene oxide( PS-b-PEO) by means of solvent vapours assisted nanoimprint lithography (SAIL). The NIL setup using solvent vapours was capable of imprinting nanoscale features over a large area and simultaneously annealing PS-b-PEO thin films. A line pattern stamp was replicated in the BCP film in over a large area with a high resolution registry, and was also observed that the PS-b-PEO film exhibited microphase segregation in the residual layer exhibits a nanodot array from showing hexagonally packed PEO dots in the PS matrix, with a diameter of 20 nm with 40 nm pitch. The order of the hexagonally arranged nanodot lattice seen in the nanodots array was quantified from SEM images using by the opposite partner method from SEM images analysis and compared with to conventionally solvent annealed BCP films, demonstrating an improvement of the ordering of up to 50%. Grazing-incidence small-angle X-ray scattering (GISAXS) study demonstrates the excellent fidelity of the pattern transfer and confirms the periodicity of the BCP in the mesas. In addition, applying the SAIL methodology to BCP thin films in nanopatterned silsequioxane substrates, it was possible to obtain multilevel structures decorated with the BCP microphase segregation. The SAIL technique is a versatile and robust platform to obtain complex high density periodic nanostructures, particularly for second generation block copolymers directed self-assembly.

  3. Ultra-thin resin embedding method for scanning electron microscopy of individual cells on high and low aspect ratio 3D nanostructures.

    PubMed

    Belu, A; Schnitker, J; Bertazzo, S; Neumann, E; Mayer, D; Offenhäusser, A; Santoro, F

    2016-07-01

    The preparation of biological cells for either scanning or transmission electron microscopy requires a complex process of fixation, dehydration and drying. Critical point drying is commonly used for samples investigated with a scanning electron beam, whereas resin-infiltration is typically used for transmission electron microscopy. Critical point drying may cause cracks at the cellular surface and a sponge-like morphology of nondistinguishable intracellular compartments. Resin-infiltrated biological samples result in a solid block of resin, which can be further processed by mechanical sectioning, however that does not allow a top view examination of small cell-cell and cell-surface contacts. Here, we propose a method for removing resin excess on biological samples before effective polymerization. In this way the cells result to be embedded in an ultra-thin layer of epoxy resin. This novel method highlights in contrast to standard methods the imaging of individual cells not only on nanostructured planar surfaces but also on topologically challenging substrates with high aspect ratio three-dimensional features by scanning electron microscopy.

  4. 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.

  5. 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

    2015-10-07

    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.

  6. 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.

  7. Interfacial scanning tunneling spectroscopy (STS) of chalcogenide/metal hybrid nanostructure

    NASA Astrophysics Data System (ADS)

    Saad, Mahmoud M.; Abdallah, Tamer; Easawi, Khalid; Negm, Sohair; Talaat, Hassan

    2015-05-01

    The electronic structure at the interface of chalcogenide/metal hybrid nanostructure (CdSe-Au tipped) had been studied by UHV scanning tunneling spectroscopy (STS) technique at room temperature. This nanostructure was synthesized by a phase transfer chemical method. The optical absorption of this hybrid nanostructure was recorded, and the application of the effective mass approximation (EMA) model gave dimensions that were confirmed by the direct measurements using the scanning tunneling microscopy (STM) as well as the high-resolution transmission electron microscope (HRTEM). The energy band gap obtained by STS agrees with the values obtained from the optical absorption. Moreover, the STS at the interface of CdSe-Au tipped hybrid nanostructure between CdSe of size about 4.1 ± 0.19 nm and Au tip of size about 3.5 ± 0.29 nm shows a band bending about 0.18 ± 0.03 eV in CdSe down in the direction of the interface. Such a result gives a direct observation of the electron accumulation at the interface of CdSe-Au tipped hybrid nanostructure, consistent with its energy band diagram. The presence of the electron accumulation at the interface of chalcogenides with metals has an important implication for hybrid nanoelectronic devices and the newly developed plasmon/chalcogenide photovoltaic solar energy conversion.

  8. High-Efficiency Robust Free-Standing Composited Phosphor Films with 2D and 3D Nanostructures for High-Power Remote White LEDs.

    PubMed

    Lai, Chun-Feng; Li, Jia-Sian; Shen, Chung-Wen

    2017-02-08

    This study demonstrated that combined free-standing quasi-amorphous/micropattern (QA/MP) composited resin film-assisted phosphor films enhanced the mechanical robustness, luminous efficacy, color rendering index (CRI), and special R9 of high-power remote warm white light-emitting diodes (WLEDs). Introducing QA/MP nanostructures into phosphor film resulted in high efficiency of remote warm WLEDs with low phosphor thickness (approximately 25 μm) and reduced the correlated color temperature (CCT) from cold white light (approximately 5565 K) to warm white light (approximately 3178 K). The QA/MP composited phosphor films (CPFs) used for high-power remote WLEDs enhanced the CRI and special R9 and reduced the CCT. These results were attributed to that QA resin film reflected the blue light and re-emitted the added red emission. CIR (84), a natural warm white CCT (3178 K), and an acceptable luminous efficacy (102.5 lm/W) were achieved from the QA/MP CPFs of high-power remote WLEDs during operation at an input power of 10 W (current of 700 mA). The bending strength of QA/MP CPFs at approximately 112 N was significantly enhanced by 40% compared with that of flat CPFs. The QA/MP CPFs applied to high-power remote WLEDs exhibited good thermal and optical stability. QA/MP CPFs were also conducted to a reliability analysis (RA), in which temperature of 85 °C and relative humidity of 85% were applied for 3288 h. Lumen maintenance was degraded by 8% during RA test because the transmittance of trimethylolopropane ethoxylate triacrylate resins was degraded under high temperature. Overall, we implemented a reliable and inexpensive technology that can potentially reduce phosphor thickness, address the out-bin problems of defective WLEDs, and fabricate flat-panel lighting source with good lighting quality.

  9. Surface modified TiO2 nanostructure with 3D urchin-like morphology for dye-sensitized solar cell application.

    PubMed

    Shin, Seong Sik; Kim, Dong Wook; Lee, Sangwook; Cho, In-Sun; Kim, Dong Hoe; Park, Jong Hoon; Hong, Kug Sun

    2012-02-01

    Three-dimensional (3D) urchin-like rutile TiO2 powders were synthesized by a mild hydrothermal method without any templates. An individual urchin-like TiO2 powder consists of self-assembled nanorods with a length of about 150 nm and width of about 10 nm. Additionally, the urchin-like TiO2 nanopowders were coated with an ultra-thin ZnO layer in order to modify the surface properties of the nanopowders, and the ZnO layer was confirmed by high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) analysis. The ZnO-modified TiO2 was used as a photoelectrode of a dye-sensitized solar cell (DSSC) and the solar cell performances were investigated. In comparison with bare TiO2, ZnO-modified TiO2 improved the photovoltaic performances, i.e., energy conversion efficiency, open circuit voltage, and short circuit current were increased. The higher DSSC performance of ZnO-modified TiO2 was attributed to its higher dye loading and lower charge recombination rate.

  10. Spectral, Magnetic and Biological Studie on Some Bivalent 3d Metal Complexes of Hydrazine Derived Schiff-Base Ligands

    PubMed Central

    Sherazi, Syed K. A.

    1997-01-01

    Metal(II) complexes of hydrazine derived Schiff-base ligands of the type M(L)2Cl2 where M = Co, Cu, Ni and Zn and L = L1 and L2 have been prepared and characterised by molar conductance, magnetic moment, elemental analysis and electronic, IR, H-NMR and 13C spectral data.The different modes of chelation of the ligands and their comparative biological properties against different bacterial species are reported. PMID:18475770

  11. 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.

  12. 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.

  13. First-order insulator-to-metal Mott transition in the paramagnetic 3D system GaTa4Se8.

    PubMed

    Camjayi, A; Acha, C; Weht, R; Rodríguez, M G; Corraze, B; Janod, E; Cario, L; Rozenberg, M J

    2014-08-22

    The nature of the Mott transition in the absence of any symmetry breaking remains a matter of debate. We study the correlation-driven insulator-to-metal transition in the prototypical 3D Mott system GaTa(4)Se(8), as a function of temperature and applied pressure. We report novel experiments on single crystals, which demonstrate that the transition is of first order and follows from the coexistence of two states, one insulating and one metallic, that we toggle with a small bias current. We provide support for our findings by contrasting the experimental data with calculations that combine local density approximation with dynamical mean-field theory, which are in very good agreement.

  14. 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.

  15. 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

  16. Nanostructured Metal Oxide Sorbents for the Collection and Recovery of Uranium from Seawater

    SciTech Connect

    Chouyyok, Wilaiwan; Warner, Cynthia L.; Mackie, Katherine E.; Warner, Marvin G.; Gill, Gary A.; Addleman, Raymond S.

    2016-02-07

    The ability to collect uranium from seawater offers the potential for a long-term green fuel supply for nuclear energy. However, extraction of uranium, and other trace minerals, is challenging due to the high ionic strength and low mineral concentrations in seawater. Herein we evaluate the use of nanostructured metal oxide sorbents for the collection and recovery of uranium from seawater. Chemical affinity, chemical adsorption capacity and kinetics of preferred sorbent materials were evaluated. High surface area manganese and iron oxide nanomaterials showed excellent performance for uranium collection from seawater. Inexpensive nontoxic carbonate solutions were demonstrated to be an effective and environmental benign method of stripping the uranium from the metal oxide sorbents. Various formats for the utilization of the nanostructured metals oxide sorbent materials are discussed including traditional and nontraditional methods such as magnetic separation. Keywords: Uranium, nano, manganese, iron, sorbent, seawater, magnetic, separations, nuclear energy

  17. One-step fabrication of crystalline metal nanostructures by direct nanoimprinting below melting temperatures

    PubMed Central

    Liu, Ze

    2017-01-01

    Controlled fabrication of metallic nanostructures plays a central role in much of modern science and technology, because changing the dimensions of a nanocrystal enables tailoring of its mechanical, electronic, optical, catalytic and antibacterial properties. Here we show direct superplastic nanoimprinting (SPNI) of crystalline metals well below their melting temperatures, generating ordered nanowire arrays with aspect ratios up to ∼2,000 and imprinting features as small as 8 nm. Surface-enhanced Raman scattering (SERS) spectra reveal strongly enhanced electromagnetic signals from the prepared nanorod arrays with sizes up to ∼100 nm, which indicates that our technique can provide an ideal way to fabricate robust SERS substrates. SPNI, as a one-step, controlled and reproducible nanofabrication method, could facilitate the applications of metal nanostructures in bio-sensing, diagnostic imaging, catalysis, food industry and environmental conservation. PMID:28348374

  18. 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

    2016-03-21

    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.

  19. 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.

  20. In vitro antileukemia, antibacterial and antifungal activities of some 3d metal complexes: chemical synthesis and structure - activity relationships.

    PubMed

    Gulea, Aurelian; Poirier, Donald; Roy, Jenny; Stavila, Vitalie; Bulimestru, Ion; Tapcov, Victor; Birca, Maria; Popovschi, Lilia

    2008-12-01

    The present paper describes the synthesis, characterization and in vitro biological evaluation screening of different classes (ammoniacates, dioximates, carboxylates, semi- and thiosemicarbazidates) of Co(II), Co(III), Cu(II), Ni(II), Mn(II), Zn(II) and Fe(III) complexes. Schiff bases were obtained from the reaction of some salicyl aldehydes with, respectively, furoylhydrazine, benzoylhydrazine, semicarbazide, thiosemicarbazide and S-methylthiosemicarbazide to give tridentate ligands containing ONO, ONS or ONN as donor atoms. The synthetic metal complexes are of various geometrical and electronic structures, thermodynamic and thermal stabilities, and magnetic and conductance properties. All complexes, except those of Cu, are octahedral. Some Cu, Co and Mn compounds have a dimeric or a polymeric structure. The composition and structure of complexes were analysed by elemental analysis, IR and (1)H NMR and (13)C NMR spectroscopies, and magnetochemical, thermoanalytical and molar conductance measurements. All ligands and metal complexes were tested as inhibitors of human leukemia (HL-60) cells growth, and the most potent, the Cu(II) complexes, have been also tested for their in vitro antibacterial and antifungal activities. Structure-activity relationships were carried out.

  1. Oxygen-deficient metal oxide nanostructures for photoelectrochemical water oxidation and other applications.

    PubMed

    Wang, Gongming; Ling, Yichuan; Li, Yat

    2012-11-07

    This review presents highlights of the latest results of studies directed at developing oxygen-deficient metal oxides, including TiO(2), WO(3), and α-Fe(2)O(3), nanostructures as electrode materials, which show significantly enhanced performance in applications for photoelectrochemical water oxidation. The enhanced photoelectrochemical performance is attributed to improved electrical conductivities by controlled incorporation of oxygen vacancies as shallow donors for metal oxides. We also discuss the potential of these oxygen-deficient metal oxides for other energy conversion and storage applications, such as photocatalytic reactions and charge storage.

  2. Metal Nanostructure Formation on Graphene: Weak versus Strong Bonding

    SciTech Connect

    Hupalo, Myron; Liu, Xiaojie; Wang, Cai-Zhuang; Lu, Wen-Cai; Yao, Yon-Xin; Ho, Kai-Ming; Tringides, Michael C.

    2011-05-10

    Graphene is an exciting material with numerous potential applications. To understand metal graphene interaction two different metals were studied. Two large Pb islands nucleate at 78K indicating fast diffusion and weak interaction(right). On the contrary, for Dysprosium a high island density is observed confirming slow diffusion and strong interaction(left).

  3. Nanostructured metal-polyaniline composites and applications thereof

    SciTech Connect

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

    2012-10-02

    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.

  4. 3D Printed Microfluidic Device with Microporous Mn2O3-Modified Screen Printed Electrode for Real-Time Determination of Heavy Metal Ions.

    PubMed

    Hong, Ying; Wu, Meiyan; Chen, Guangwei; Dai, Ziyang; Zhang, Yizhou; Chen, Guosong; Dong, Xiaochen

    2016-12-07

    Fabricating portable devices for the determination of heavy metal ions is an ongoing challenge. Here, a 3D printing approach was adopted to fabricate a microfluidic electrochemical sensor with the desired shape in which the model for velocity profiles in microfluidic cells was built and optimized by the finite element method (FEM). The electrode in the microfluidic cell was a flexible screen-printed electrode (SPE) modified with porous Mn2O3 derived from manganese containing metal-organic framework (Mn-MOF). The microfluidic device presented superior electrochemical detection properties toward heavy metal ions. The calibration curves at the modified SPE for Cd(II) and Pb(II) covered two linear ranges varying from 0.5 to 8 and 10 to 100 μg L(-1), respectively. The limits of detection were estimated to be 0.5 μg L(-1) for Cd(II) and 0.2 μg L(-1) for Pb(II), which were accordingly about 6 and 50 times lower than the guideline values proposed by the World Health Organization. Furthermore, the microfluidic device was connected to iPad via a USB to enable real-time household applications. Additionally, the sensing system exhibited a better stability and reproducibility compared with traditional detecting system which offered a promising prospect for the detection of heavy metal ions especially in household and resource-limited occasions.

  5. Micromechanics of Amorphous Metal/Polymer Hybrid Structures with 3D Cellular Architectures: Size Effects, Buckling Behavior, and Energy Absorption Capability.

    PubMed

    Mieszala, Maxime; Hasegawa, Madoka; Guillonneau, Gaylord; Bauer, Jens; Raghavan, Rejin; Frantz, Cédric; Kraft, Oliver; Mischler, Stefano; Michler, Johann; Philippe, Laetitia

    2017-02-01

    By designing advantageous cellular geometries and combining the material size effects at the nanometer scale, lightweight hybrid microarchitectured materials with tailored structural properties are achieved. Prior studies reported the mechanical properties of high strength cellular ceramic composites, obtained by atomic layer deposition. However, few studies have examined the properties of similar structures with metal coatings. To determine the mechanical performance of polymer cellular structures reinforced with a metal coating, 3D laser lithography and electroless deposition of an amorphous layer of nickel-boron (NiB) is used for the first time to produce metal/polymer hybrid structures. In this work, the mechanical response of microarchitectured structures is investigated with an emphasis on the effects of the architecture and the amorphous NiB thickness on their deformation mechanisms and energy absorption capability. Microcompression experiments show an enhancement of the mechanical properties with the NiB thickness, suggesting that the deformation mechanism and the buckling behavior are controlled by the brittle-to-ductile transition in the NiB layer. In addition, the energy absorption properties demonstrate the possibility of tuning the energy absorption efficiency with adequate designs. These findings suggest that microarchitectured metal/polymer hybrid structures are effective in producing materials with unique property combinations.

  6. Origin of enhanced visible-light photocatalytic activity of transition-metal (Fe, Cr and Co)-doped CeO2: effect of 3 d orbital splitting

    NASA Astrophysics Data System (ADS)

    Yang, Ke; Li, Dong-Feng; Huang, Wei-Qing; Xu, Liang; Huang, Gui-Fang; Wen, Shuangchun

    2017-01-01

    Enhanced visible-light photocatalytic activity of transition-metal-doped ceria (CeO2) nanomaterials has experimentally been demonstrated, whereas there are very few reports mentioning the mechanism of this behavior. Here, we use first-principles calculations to explore the origin of enhanced photocatalytic performance of CeO2 doped with transition metal impurities (Fe, Cr and Co). When a transition metal atom substitutes a Ce atom into CeO2, t 2g and e g levels of 3 d orbits appear in the middle of band gap owing to the effect of cubic ligand field, and the former is higher than latter. Interestingly, t 2g subset of FeCe (CoCe and CrCe)-Vo-CeO2 splits into two parts: one merges into the conduction band, the other as well as e g will remain in the gap, because O vacancy defect adjacent to transition metal atom will break the symmetry of cubic ligand field. These e g and t 2g levels in the band gap are beneficial for absorbing visible-light and enhancing quantum efficiency because of forbidden transition, which is one key factor for enhanced visible-light photocatalytic activity. The band gap narrowing also leads to a redshift of optical absorbance and high photoactivity. These findings can rationalize the available experimental results and provide some new insights for designing CeO2-based photocatalysts with high photocatalytic performance.

  7. Soft Nanoimprint Lithography for Direct Printing of Crystalline Metal Oxide Nanostructures

    NASA Astrophysics Data System (ADS)

    Kothari, Rohit; Beaulieu, Michael; Watkins, James

    2015-03-01

    We demonstrate a solution-based soft nanoimprint lithography technique to directly print dimensionally-stable crystalline metal oxide nanostructures. A patterned PDMS stamp is used in combination with a UV/thermal cure step to imprint a resist containing high concentrations of crystalline nanoparticles in an inorganic/organic binder phase. The as-imprinted nanostructures are highly crystalline and therefore undergo little shrinkage (less than 5% in some cases) upon thermal annealing. High aspect ratio nanostructures and sub-100 nm features are easily realized. Residual layer free direct imprinting (no etching) was achieved by choosing the resist with the appropriate surface energy to ensure dewetting at stamp-substrate interface. The technique was further extended to stack the nanostructures by deploying a layer-by-layer imprint strategy. The method is scalable and can produce large area device quality nanostructures in a rapid fashion at a low cost. CeO2, ITO and TiO2 nanopatterns are illustrated for their potential use in fuel cell electrodes, solar cell electrodes and photonic devices, respectively.

  8. Photoemission spectra and density functional theory calculations of 3d transition metal-aqua complexes (Ti-Cu) in aqueous solution.

    PubMed

    Yepes, Diana; Seidel, Robert; Winter, Bernd; Blumberger, Jochen; Jaque, Pablo

    2014-06-19

    Photoelectron spectroscopy measurements and density functional calculations are combined to determine the lowest electron binding energies of first-row transition-metal aqua ions, titanium through copper, with 3d(1) through 3d(9) electronic configurations, in their most common oxidation states. Vertical ionization energies are found to oscillate considerably between 6.76 and 9.65 eV for the dications and between 7.05 and 10.28 eV for the respective trivalent cations. The metal cations are modeled as [M(H2O)n](q+) clusters (q = 2, 3, and 4; n = 6 and 18) surrounded by continuum solvent. The performance of 10 exchange-correlation functionals, two GGAs, three MGGAs, two HGGAs and three HMGGAs, combined with the MDF10(ECP)/6-31+G(d,p) basis set is assessed for 11 M-O bond distances, 10 vertical ionization energies, 6 adiabatic ionization energies, and the associated reorganization free energies. We find that for divalent cations the HGGA and HMGGA functionals in combination with the 18 water model show the best agreement with experimental vertical ionization energies and geometries; for trivalent ions, the MGGA functionals perform best. The corresponding reorganization free energies (λo) of the oxidized ions are significantly underestimated with all DFT functionals and cluster models. This indicates that the structural reorganization of the solvation shell upon ionization is not adequately accounted for by the simple solvation models used, emphasizing the importance of extended sampling of thermally accessible solvation structures for an accurate computation of this quantity. The photoelectron spectroscopy measurements reported herein provide a comprehensive set of transition-metal redox energetic quantities for future electronic structure benchmarks.

  9. Nanostructured metal chalcogenides: synthesis, modification, and applications in energy conversion and storage devices.

    PubMed

    Gao, Min-Rui; Xu, Yun-Fei; Jiang, Jun; Yu, Shu-Hong

    2013-04-07

    Advanced energy conversion and storage (ECS) devices (including fuel cells, photoelectrochemical water splitting cells, solar cells, Li-ion batteries and supercapacitors) are expected to play a major role in the development of sustainable technologies that alleviate the energy and environmental challenges we are currently facing. The successful utilization of ECS devices depends critically on synthesizing new nanomaterials with merits of low cost, high efficiency, and outstanding properties. Recent progress has demonstrated that nanostructured metal chalcogenides (MCs) are very promising candidates for efficient ECS systems based on their unique physical and chemical properties, such as conductivity, mechanical and thermal stability and cyclability. In this review, we aim to provide a summary on the liquid-phase synthesis, modifications, and energy-related applications of nanostructured metal chalcogenide (MC) materials. The liquid-phase syntheses of various MC nanomaterials are primarily categorized with the preparation method (mainly 15 kinds of methods). To obtain optimized, enhanced or even new properties, the nanostructured MC materials can be modified by other functional nanomaterials such as carbon-based materials, noble metals, metal oxides, or MCs themselves. Thus, this review will then be focused on the recent strategies used to realize the modifications of MC nanomaterials. After that, the ECS applications of the MC/modified-MC nanomaterials have been systematically summarized based on a great number of successful cases. Moreover, remarks on the challenges and perspectives for future MC research are proposed (403 references).

  10. Ablation and nanostructuring of metals by femtosecond laser pulses

    SciTech Connect

    Ashitkov, S I; Komarov, P S; Ovchinnikov, A V; Struleva, E V; Agranat, M B; Zhakhovskii, V V; Inogamov, N A

    2014-06-30

    Using an interferometric continuous monitoring technique, we have investigated the motion of the surface of an aluminium target in the case of femtosecond laser ablation at picosecond time delays relative to the instant of laser exposure. Measurements of the temporal target dispersion dynamics, molecular dynamics simulation results and the morphology of the ablation crater have demonstrated a thermomechanical (spall) nature of the disruption of the condensed phase due to the cavitation-driven formation and growth of vapour phase nuclei upon melt expansion, followed by the formation of surface nanostructures upon melt solidification. The tensile strength of heated aluminium in a condensed state has been determined experimentally at an expansion rate of ∼10{sup 9} s{sup -1}. (extreme light fields and their applications)

  11. High-performance electrocatalysis using metallic cobalt pyrite (CoS₂) micro- and nanostructures.

    PubMed

    Faber, Matthew S; Dziedzic, Rafal; Lukowski, Mark A; Kaiser, Nicholas S; Ding, Qi; Jin, Song

    2014-07-16

    The development of efficient and robust earth-abundant electrocatalysts for the hydrogen evolution reaction (HER) is an ongoing challenge. We report metallic cobalt pyrite (cobalt disulfide, CoS2) as one such high-activity candidate material and demonstrate that its specific morphology--film, microwire, or nanowire, made available through controlled synthesis--plays a crucial role in determining its overall catalytic efficacy. The increase in effective electrode surface area that accompanies CoS2 micro- and nanostructuring substantially boosts its HER catalytic performance, with CoS2 nanowire electrodes achieving geometric current densities of -10 mA cm(-2) at overpotentials as low as -145 mV vs the reversible hydrogen electrode. Moreover, micro- and nanostructuring of the CoS2 material has the synergistic effect of increasing its operational stability, cyclability, and maximum achievable rate of hydrogen generation by promoting the release of evolved gas bubbles from the electrode surface. The benefits of catalyst micro- and nanostructuring are further demonstrated by the increased electrocatalytic activity of CoS2 nanowire electrodes over planar film electrodes toward polysulfide and triiodide reduction, which suggests a straightforward way to improve the performance of quantum dot- and dye-sensitized solar cells, respectively. Extension of this micro- and nanostructuring strategy to other earth-abundant materials could similarly enable inexpensive electrocatalysts that lack the high intrinsic activity of the noble metals.

  12. Core/shell nano-structuring of metal oxide semiconductors and their photocatalytic studies

    NASA Astrophysics Data System (ADS)

    Balakumar, S.; Rakkesh, R. Ajay

    2013-02-01

    Core/Shell Nanostructures of Metal Oxide Semiconductors (MOS) have attracted much attention because of their most fascinating tunable applications. These core shell morphologies can be easily engineered to enhance the unique properties of the metal-oxide nanostructures, which make them suitable as photocatalyst due to their high catalytic activity, substantial stability, and brilliant perspective in applications. This paper provides an overview on our work on the synthesis of some interesting core/ shell nanostructures of MOS such as ZnO-TiO2, ZnO-MoO3, and V2O5-TiO2 using a low temperature wet chemical route and hydrothermal techniques and their photocatalytic properties from the aspects of different shell materials and shell thicknesses. The effect of process parameters such as pH, temperature, and ratio of core and shell materials, was systematically studied. Here the evidence for the core shell formation with different shell thicknesses came from the X-ray diffraction peak intensities. The shell thickness variation was also confirmed by Transmission Electron Microscopic studies. Effect of shell thickness on optical band gap of the core shell fabricated was also investigated using DRS UV-Visible spectroscopy. A comprehensive study was carried out for the photocatalytic efficiency of core shell nanostructures by evaluating the photo-degradation of Acridine Orange (AO) dye in aqueous solution under visible and solar light irradiations. These results offered simple approaches to the nanoscale engineering and synthesis of MOS hybrid systems to serve as better photocatalytic materials.

  13. A two-storey structured photoanode of a 3D Cu2ZnSnS4/CdS/ZnO@steel composite nanostructure for efficient photoelectrochemical hydrogen generation

    NASA Astrophysics Data System (ADS)

    Choi, Youngwoo; Baek, Minki; Zhang, Zhuo; Dao, Van-Duong; Choi, Ho-Suk; Yong, Kijung

    2015-09-01

    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.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

  14. Asymmetric Supercapacitors Using 3D Nanoporous Carbon and Cobalt Oxide Electrodes Synthesized from a Single Metal-Organic Framework.

    PubMed

    Salunkhe, Rahul R; Tang, Jing; Kamachi, Yuichiro; Nakato, Teruyuki; Kim, Jung Ho; Yamauchi, Yusuke

    2015-06-23

    Nanoporous carbon and nanoporous cobalt oxide (Co3O4) materials have been selectively prepared from a single metal-organic framework (MOF) (zeolitic imidazolate framework, ZIF-67) by optimizing the annealing conditions. The resulting ZIF-derived carbon possesses highly graphitic walls and a high specific surface area of 350 m(2)·g(-1), while the resulting ZIF-derived nanoporous Co3O4 possesses a high specific surface area of 148 m(2)·g(-1) with much less carbon content (1.7 at%). When nanoporous carbon and nanoporous Co3O4 were tested as electrode materials for supercapacitor application, they showed high capacitance values (272 and 504 F·g(-1), respectively, at a scan rate of 5 mV·s(-1)). To further demonstrate the advantages of our ZIF-derived nanoporous materials, symmetric (SSCs) and asymmetric supercapacitors (ASCs) were also fabricated using nanoporous carbon and nanoporous Co3O4 electrodes. Improved capacitance performance was successfully realized for the ASC (Co3O4//carbon), better than those of the SSCs based on nanoporous carbon and nanoporous Co3O4 materials (i.e., carbon//carbon and Co3O4//Co3O4). The developed ASC with an optimal mass loading can be operated within a wide potential window of 0.0-1.6 V, which leads to a high specific energy of 36 W·h·kg(-1). More interestingly, this ASC also exhibits excellent rate capability (with the highest specific power of 8000 W·kg(-1) at a specific energy of 15 W·h·kg(-1)) combined with long-term stability up to 2000 cycles.

  15. Heterometallic 3d-4f single-molecule magnets: ligand and metal ion influences on the magnetic relaxation.

    PubMed

    Langley, Stuart K; Le, Crystal; Ungur, Liviu; Moubaraki, Boujemaa; Abrahams, Brendan F; Chibotaru, Liviu F; Murray, Keith S

    2015-04-06

    Six tetranuclear 3d–4f single-molecule magnet (SMM) complexes formed using N-n-butyldiethanolamine and N-methyldiethanolamine in conjunction with ortho- and para-substituted benzoic acid and hexafluoroacetoacetone ligands yield two families, both having a butterfly metallic core. The first consists of four complexes of type {Co2(III)Dy2(III)} and {Co2(III)Co(II)Dy(III)} using N-n-butyldiethanolamine with variation of the carboxylate ligand. The anisotropy barriers are 80 cm–1, (77 and 96 cm–1—two relaxation processes occur), 117 and 88 cm–1, respectively, each following a relaxation mechanism from a single DyIII ion. The second family consists of a {Co2(III)Dy2(III)} and a {Cr2(III)Dy2(III)} complex, from the ligand combination of N-methyldiethanolamine and hexafluoroacetylacetone. Both show SMM behavior, the Co(III) example displaying an anisotropy barrier of 23 cm–1. The Cr(III) complex displays a barrier of 28 cm–1, with longer relaxation times and open hysteresis loops, the latter of which is not seen in the Co(III) case. This is a consequence of strong Dy(III)–Cr(III) magnetic interactions, with the relaxation arising from the electronic structure of the whole complex and not from a single DyIII ion. The results suggest that the presence of strong exchange interactions lead to significantly longer relaxation times than in isostructural complexes where the exchange is weak. The study also suggests that electron-withdrawing groups on both bridging (carboxylate) and terminal (β-diketonate) ligands enhance the anisotropy barrier.

  16. Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts

    NASA Astrophysics Data System (ADS)

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-04-01

    An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail and using the unique knowledge obtained for rationalizing their synthesis and properties targeted for optimization is described and exemplified on Pt-Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. In particular, PtxRu100-x alloy NPs, where x = 31, 49 and 75, are synthesized by wet chemistry and activated catalytically by a post-synthesis treatment involving heating under controlled N2-H2 atmosphere. So-activated NPs are evaluated as catalysts for gas-phase CO oxidation and ethanol electro-oxidation reactions taking place in fuel cells. Both as-synthesized and activated NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models both for as-synthesized and activated NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modelling Sutton-Chen method. Models are refined against the experimental PDF data by reverse Monte Carlo simulations and analysed in terms of prime structural characteristics such as metal-to-metal bond lengths, bond angles and first coordination numbers for Pt and Ru atoms. Analysis indicates that, though of a similar type, the atomic structure of as-synthesized and respective activated NPs differ in several details of importance to NP catalytic properties. Structural characteristics of activated NPs and data for their catalytic activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the

  17. Synthesis-atomic structure-properties relationships in metallic nanoparticles by total scattering experiments and 3D computer simulations: case of Pt-Ru nanoalloy catalysts.

    PubMed

    Prasai, Binay; Ren, Yang; Shan, Shiyao; Zhao, Yinguang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian; Petkov, Valeri

    2015-05-07

    An approach to determining the 3D atomic structure of metallic nanoparticles (NPs) in fine detail and using the unique knowledge obtained for rationalizing their synthesis and properties targeted for optimization is described and exemplified on Pt-Ru alloy NPs of importance to the development of devices for clean energy conversion such as fuel cells. In particular, PtxRu100-x alloy NPs, where x = 31, 49 and 75, are synthesized by wet chemistry and activated catalytically by a post-synthesis treatment involving heating under controlled N2-H2 atmosphere. So-activated NPs are evaluated as catalysts for gas-phase CO oxidation and ethanol electro-oxidation reactions taking place in fuel cells. Both as-synthesized and activated NPs are characterized structurally by total scattering experiments involving high-energy synchrotron X-ray diffraction coupled to atomic pair distribution functions (PDFs) analysis. 3D structure models both for as-synthesized and activated NPs are built by molecular dynamics simulations based on the archetypal for current theoretical modelling Sutton-Chen method. Models are refined against the experimental PDF data by reverse Monte Carlo simulations and analysed in terms of prime structural characteristics such as metal-to-metal bond lengths, bond angles and first coordination numbers for Pt and Ru atoms. Analysis indicates that, though of a similar type, the atomic structure of as-synthesized and respective activated NPs differ in several details of importance to NP catalytic properties. Structural characteristics of activated NPs and data for their catalytic activity are compared side by side and strong evidence found that electronic effects, indicated by significant changes in Pt-Pt and Ru-Ru metal bond lengths at NP surface, and practically unrecognized so far atomic ensemble effects, indicated by distinct stacking of atomic layers near NP surface and prevalence of particular configurations of Pt and Ru atoms in these layers, contribute to the

  18. Nanostructured Zr-Pd Metallic Glass Thin Film for Biochemical Applications

    NASA Astrophysics Data System (ADS)

    Ketov, Sergey V.; Shi, Xuetao; Xie, Guoqiang; Kumashiro, Ryotaro; Churyumov, Alexander Yu.; Bazlov, Andrey I.; Chen, Na; Ishikawa, Yoshifumi; Asao, Naoki; Wu, Hongkai; Louzguine-Luzgin, Dmitri V.

    2015-01-01

    Zr-Pd metallic glassy thin films with a hierarchical nano-scale structure, produced by magnetron sputtering of the Zr and Pd powder mixture, demonstrate a unique combination of physical and biochemical properties. Thermal stability of the nano-structured glassy samples, their resistance to oxidation in dry air and phase transformation behavior are discussed in the present work. These binary alloy samples also show exceptionally high corrosion resistance and spontaneous passivation in a simulated body fluid. Experiments on the catalytic activity and biocompatibility of this nanostructured metallic glass indicate that this is a very suitable material for biochemical applications. Compared to the multicomponent alloys studied earlier this binary alloy has much simpler chemical composition, which makes preparation of the sample with defined stoichiometry easier, especially when the elements have different sputtering rates.

  19. 3D Framework DNA Origami with Layered Crossovers.

    PubMed

    Hong, Fan; Jiang, Shuoxing; Wang, Tong; Liu, Yan; Yan, Hao

    2016-10-04

    Designer DNA architectures with nanoscale geometric controls provide a programmable molecular toolbox for engineering complex nanodevices. Scaffolded DNA origami has dramatically improved our ability to design and construct DNA nanostructures with finite size and spatial addressability. Here we report a novel design strategy to engineer multilayered wireframe DNA structures by introducing crossover pairs that connect neighboring layers of DNA double helices. These layered crossovers (LX) allow the scaffold or helper strands to travel through different layers and can control the relative orientation of DNA helices in neighboring layers. Using this design strategy, we successfully constructed four versions of two-layer parallelogram structures with well-defined interlayer angles, a three-layer structure with triangular cavities, and a 9- and 15-layer square lattices. This strategy provides a general route to engineer 3D framework DNA nanostructures with controlled cavities and opportunities to design host-guest networks analogs to those produced with metal organic frameworks.

  20. Synthesizing 2D and 3D Selenidostannates in Ionic Liquids: The Synergistic Structure-Directing Effects of Ionic Liquids and Metal-Amine Complexes.

    PubMed

    Du, Cheng-Feng; Shen, Nan-Nan; Li, Jian-Rong; Hao, Min-Ting; Wang, Zi; Huang, Xiao-Ying

    2016-05-20

    Presented are the ionothermal syntheses, characterizations, and properties of a series of two- and three-dimensional selenidostannate compounds synergistically directed by metal-amine complex (MAC) cations and ionic liquids (ILs) of [Bmmim]Cl (Bmmim=1-butyl-2,3-dimethylimidazolium). Four selenidostannates, namely, 2D-(Bmmim)3 [Ni(en)3 ]2 [Sn9 Se21 ]Cl (1, en=ethylenediamine), 2D-(Bmmim)8 [Ni2 (teta)2 (μ-teta)]Sn18 Se42 (2, teta=triethylenetetramine), 2D-(Bmmim)4 [Ni(tepa)Cl]2 [Ni(tepa)Sn12 Se28 ] (3, tepa=tetraethylenepentamine), and 3D-(Bmmim)2 [Ni(1,2-pda)3 ]Sn8 Se18 (4, 1,2-pda=1,2-diaminopropane), were obtained. Single-crystal X-ray diffraction analyses revealed that compounds 1 and 2 possess a lamellar anionic [Sn3 Se7 ]n (2n-) structure comprising distinct eight-membered ring units, whereas 3 features a MAC-decorated anionic [Ni(tepa)Sn12 Se28 ]n (6n-) layered structure. In contrast to 1-3, compound 4 exhibits a 3D open framework of anionic [Sn4 Se9 ]n (2n-) . The structural variation from 1 to 4 clearly indicates that on the basis of the synergistic structure-directing ability of the MACs and ILs, variation of the organic polyamine ligand has a significant impact on the formation of selenidostannates.

  1. Bio-Conjugated CNT-Bridged 3D Porous Graphene Oxide Membrane for Highly Efficient Disinfection of Pathogenic Bacteria and Removal of Toxic Metals from Water.

    PubMed

    Nellore, Bhanu Priya Viraka; Kanchanapally, Rajashekhar; Pedraza, Francisco; Sinha, Sudarson Sekhar; Pramanik, Avijit; Hamme, Ashton T; Arslan, Zikri; Sardar, Dhiraj; Ray, Paresh Chandra

    2015-09-02

    More than a billion people lack access to safe drinking water that is free from pathogenic bacteria and toxic metals. The World Health Organization estimates several million people, mostly children, die every year due to the lack of good quality water. Driven by this need, we report the development of PGLa antimicrobial peptide and glutathione conjugated carbon nanotube (CNT) bridged three-dimensional (3D) porous graphene oxide membrane, which can be used for highly efficient disinfection of Escherichia coli O157:H7 bacteria and removal of As(III), As(V), and Pb(II) from water. Reported results demonstrate that versatile membrane has the capability to capture and completely disinfect pathogenic pathogenic E. coli O157:H7 bacteria from water. Experimentally observed disinfection data indicate that the PGLa attached membrane can dramatically enhance the possibility of destroying pathogenic E. coli bacteria via synergistic mechanism. Reported results show that glutathione attached CNT-bridged 3D graphene oxide membrane can be used to remove As(III), As(V), and Pb(II) from water sample at 10 ppm level. Our data demonstrated that PGLa and glutathione attached membrane has the capability for high efficient removal of E. coli O157:H7 bacteria, As(III), As(V), and Pb(II) simultaneously from Mississippi River water.

  2. Electrochemical detectors based on carbon and metallic nanostructures in capillary and microchip electrophoresis.

    PubMed

    García-Carmona, Laura; Martín, Aida; Sierra, Tania; González, María Cristina; Escarpa, Alberto

    2017-01-01

    Carbon and metallic-based nanostructures have been progressively implemented as innovative electrochemical detectors in CE and microchip electrophoresis (ME). For both type of nanomaterials and toward selected examples, this review details the impact of these nanomaterials for enhanced detection performance in CE, ME, and paper-based microfluidic devices. The analytical performance and the analytical potential in real world applications is also presented and discussed.

  3. Photonic Nanostructures Patterned by Thermal Nanoimprint Directly into Organo-Metal Halide Perovskites.

    PubMed

    Pourdavoud, Neda; Wang, Si; Mayer, André; Hu, Ting; Chen, Yiwang; Marianovich, André; Kowalsky, Wolfgang; Heiderhoff, Ralf; Scheer, Hella-Christin; Riedl, Thomas

    2017-03-01

    Photonic nanostructures are created in organo-metal halide perovskites by thermal nanoimprint lithography at a temperature of 100 °C. The imprinted layers are significantly smoothened compared to the initially rough, polycrystalline layers and the impact of surface defects is substantially mitigated upon imprint. As a case study, 2D photonic crystals are shown to afford lasing with ultralow lasing thresholds at room temperature.

  4. Angle-resolved surface-enhanced Raman scattering on metallic nanostructured plasmonic crystals.

    PubMed

    Baumberg, Jeremy J; Kelf, Timothy A; Sugawara, Yoshihiro; Cintra, Suzanne; Abdelsalam, Mamdouh E; Bartlett, Phillip N; Russell, Andrea E

    2005-11-01

    Surface-enhanced Raman scattering is an ideal tool for identifying molecules from the "fingerprint" of their molecular bonds; unfortunately, this process lacks a full microscopic understanding and, practically, is plagued with irreproducibility. Using nanostructured metal surfaces, we demonstrate strong correlations between plasmon resonances and Raman enhancements. Evidence for simultaneous ingoing and outgoing resonances in wavelength and angle sheds new light on the Raman enhancement process, allowing optimization of a new generation of reproducible Raman substrates.

  5. Nanostructured metal oxide-based materials as advanced anodes for lithium-ion batteries.

    PubMed

    Wu, Hao Bin; Chen, Jun Song; Hng, Huey Hoon; Lou, Xiong Wen David

    2012-04-21

    The search for new electrode materials for lithium-ion batteries (LIBs) has been an important way to satisfy the ever-growing demands for better performance with higher energy/power densities, improved safety and longer cycle life. Nanostructured metal oxides exhibit good electrochemical properties, and they are regarded as promising anode materials for high-performance LIBs. In this feature article, we will focus on three different categories of metal oxides with distinct lithium storage mechanisms: tin dioxide (SnO(2)), which utilizes alloying/dealloying processes to reversibly store/release lithium ions during charge/discharge; titanium dioxide (TiO(2)), where lithium ions are inserted/deinserted into/out of the TiO(2) crystal framework; and transition metal oxides including iron oxide and cobalt oxide, which react with lithium ions via an unusual conversion reaction. For all three systems, we will emphasize that creating nanomaterials with unique structures could effectively improve the lithium storage properties of these metal oxides. We will also highlight that the lithium storage capability can be further enhanced through designing advanced nanocomposite materials containing metal oxides and other carbonaceous supports. By providing such a rather systematic survey, we aim to stress the importance of proper nanostructuring and advanced compositing that would result in improved physicochemical properties of metal oxides, thus making them promising negative electrodes for next-generation LIBs.

  6. Ion irradiation induced element-enriched and depleted nanostructures in Zr-Al-Cu-Ni metallic glass

    SciTech Connect

    Chen, H. C.; Liu, R. D.; Yan, L. E-mail: zhouxingtai@sinap.ac.cn; Zhou, X. T. E-mail: zhouxingtai@sinap.ac.cn; Cao, G. Q.; Wang, G.

    2015-07-21

    The microstructural evolution of a Zr-Al-Cu-Ni metallic glass induced by irradiation with Ar ions was investigated. Under ion irradiation, the Cu- and Ni-enriched nanostructures (diameter of 30–50 nm) consisted of crystalline and amorphous structures were formed. Further, Cu- and Ni-depleted nanostructures with diameters of 5–20 nm were also observed. The formation of these nanostructures can be ascribed to the migration of Cu and Ni atoms in the irradiated metallic glass.

  7. In situ synthesized 3D heterometallic metal-organic framework (MOF) as a high-energy-density material shows high heat of detonation, good thermostability and insensitivity.

    PubMed

    Feng, Yaya; Liu, Xiangyu; Duan, Linqiang; Yang, Qi; Wei, Qing; Xie, Gang; Chen, Sanping; Yang, Xuwu; Gao, Shengli

    2015-02-07

    A reticular 3D heterometallic metal-organic framework (MOF), [Cu4Na(Mtta)5(CH3CN)]n () (N% = 40.08%), has been synthesized, using a 5-methyl tetrazole (Mtta) ligand formed from acetonitrile and azide, through in situ synthesis and structurally characterized by X-ray single crystal diffraction. The fluorescence spectra demonstrate that undergoes an interesting structural transformation in aqueous solution, yielding the compound [Cu4Na(Mtta)5H2O]n () as confirmed by (1)H NMR, IR and PXRD. Thermoanalysis showed that possesses excellent thermostability up to 335 °C. The calculated detonation properties and the sensitivity test illustrate that compound could be used as a potential explosive. In addition, the non-isothermal kinetics for were studied using the Kissinger and Ozawa-Doyle methods. The enthalpy of formation was obtained from the determination of the constant-volume combustion energy.

  8. Modeling STM tips by single absorbed atoms on W(100) films: 3d, 4d and 5d transition metal atoms

    NASA Astrophysics Data System (ADS)

    Hofer, Werner; Redinger, Josef; Kresse, Georg; Podloucky, Raimund

    2000-03-01

    In order to provide comprehensive data on the electronic structure of realistic STM-tips we have calculated W(100) films with single 3d, 4d and 5d transition metal apex atoms by first principles molecular dynamics and full potential methods. Molecular dynamics using ultrasoft pseudopotentials (VASP) has been used to determine the relaxation of the surface layers. The electronic structure of the relaxed film has been calculated by a first principles full potential method with two-dimensional boundary conditions (FLEUR), which seems most suitable to reproduce subtle surface effects. The results suggest that the chemical nature of the tip apex determines to a high degree achievable corrugations and that correct results for the current and corrugation values in a perturbation approach can only be obtained by including the full electronic structure of the tip.

  9. Electronic structure of the chiral helimagnet and 3d-intercalated transition metal dichalcogenide Cr1/3NbS2

    DOE PAGES

    Sirca, N.; Mo, S. -K.; Bondino, F.; ...

    2016-08-18

    The electronic structure of the chiral helimagnet Cr1/3NbS2 has been studied with core level and angle-resolved photoemission spectroscopy (ARPES). Intercalated Cr atoms are found to be effective in donating electrons to the NbS2 layers but also cause significant modifications of the electronic structure of the host NbS2 material. Specifically, the data provide evidence that a description of the electronic structure of Cr1/3NbS2 on the basis of a simple rigid band picture is untenable. The data also reveal substantial inconsistencies with the predictions of standard density functional theory. In conclusion, the relevance of these results to the attainment of a correctmore » description of the electronic structure of chiral helimagnets, magnetic thin films/multilayers, and transition metal dichalcogenides intercalated with 3d magnetic elements is discussed.« less

  10. Electronic structure of the chiral helimagnet and 3d-intercalated transition metal dichalcogenide Cr1/3NbS2

    SciTech Connect

    Sirca, N.; Mo, S. -K.; Bondino, F.; Pis, I.; Nappini, S.; Vilmercati, P.; Yi, Jieyu; Gai, Zheng; Snijders, Paul C.; Das, P. K.; Vobornik, I.; Ghimire, N. J.; Koehler, Michael R.; Sopkota, D.; Parker, David S.; Mandrus, D. G.; Mannella, Norman

    2016-08-18

    The electronic structure of the chiral helimagnet Cr1/3NbS2 has been studied with core level and angle-resolved photoemission spectroscopy (ARPES). Intercalated Cr atoms are found to be effective in donating electrons to the NbS2 layers but also cause significant modifications of the electronic structure of the host NbS2 material. Specifically, the data provide evidence that a description of the electronic structure of Cr1/3NbS2 on the basis of a simple rigid band picture is untenable. The data also reveal substantial inconsistencies with the predictions of standard density functional theory. In conclusion, the relevance of these results to the attainment of a correct description of the electronic structure of chiral helimagnets, magnetic thin films/multilayers, and transition metal dichalcogenides intercalated with 3d magnetic elements is discussed.

  11. Precipitation of heterogeneous nanostructures: Metal nanoparticles and dielectric nanocrystallites

    SciTech Connect

    Masai, Hirokazu; Takahashi, Yoshihiro; Fujiwara, Takumi; Tokuda, Yomei; Yoko, Toshinobu

    2010-07-15

    Heterogeneous precipitation of nanocrystallites of metallic Bi and anatase was observed in CaO-Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-TiO{sub 2} glass-ceramics. Addition of AlN reduced the Bi{sub 2}O{sub 3} to Bi metal nanoparticles, which were uniformly dispersed in the glass. After heat-treatment of the Bi-precipitated glass around the glass transition temperature, nanocrystalline anatase precipitated out without aggregation of the Bi metal particles. It was found that the anatase nanocrystal size was affected by the distance between a nanocrystal and a precipitated Bi nanoparticle. The glass-ceramic produced is a functional material containing a random dispersion of different types of nanoparticles with different dielectric constants.

  12. Intrinsic electrical conductivity of nanostructured metal-organic polymer chains

    PubMed Central

    Hermosa, Cristina; Vicente Álvarez, Jose; Azani, Mohammad-Reza; Gómez-García, Carlos J.; Fritz, Michelle; Soler, Jose M.; Gómez-Herrero, Julio; Gómez-Navarro, Cristina; Zamora, Félix

    2013-01-01

    One-dimensional conductive polymers are attractive materials because of their potential in flexible and transparent electronics. Despite years of research, on the macro- and nano-scale, structural disorder represents the major hurdle in achieving high conductivities. Here we report measurements of highly ordered metal-organic nanoribbons, whose intrinsic (defect-free) conductivity is found to be 104 S m−1, three orders of magnitude higher than that of our macroscopic crystals. This magnitude is preserved for distances as large as 300 nm. Above this length, the presence of structural defects (~ 0.5%) gives rise to an inter-fibre-mediated charge transport similar to that of macroscopic crystals. We provide the first direct experimental evidence of the gapless electronic structure predicted for these compounds. Our results postulate metal-organic molecular wires as good metallic interconnectors in nanodevices. PMID:23591876