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Sample records for atomically flat single-crystalline

  1. Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry

    Energy Technology Data Exchange (ETDEWEB)

    Huang, J.S.; Geisler, P.; Bruening, C.; Kern, J.; Prangsma, J.C.; Wu, X.; Feichtner, Thorsten; Ziegler, J.; Weinmann, P.; Kamp, M.; Forchel, A.; Hecht, B. [Wilhelm-Conrad-Roentgen-Center for Complex Material Systems, University of Wuerzburg (Germany); Biagioni, P. [CNISM, Dipartimento di Fisica, Politecnico di Milano (Italy)

    2011-07-01

    Deep subwavelength integration of high-definition plasmonic nano-structures is of key importance for the development of future optical nanocircuitry. So far the experimental realization of proposed extended plasmonic networks remains challenging, mainly due to the multi-crystallinity of commonly used thermally evaporated gold layers. Resulting structural imperfections in individual circuit elements drastically reduce the yield of functional integrated nanocircuits. Here we demonstrate the use of very large but thin chemically grown single-crystalline gold flakes. After immobilization on any arbitrary surface, they serve as an ideal basis for focused-ion beam milling. We present high-definition ultra-smooth gold nanostructures with reproducible nanosized features over micrometer lengthscales. By comparing multi- and single-crystalline optical antennas we prove that the latter have superior optical properties which are in good agreement with numerical simulations.

  2. Atomically flat single-crystalline gold nanostructures for plasmonic nanocircuitry

    CERN Document Server

    Huang, Jer-Shing; Geisler, Peter; Brüning, Christoph; Kern, Johannes; Prangsma, Jord C; Weinmann, Pia; Kamp, Martin; Forchel, Alfred; Biagioni, Paolo; Sennhauser, Urs; Hecht, Bert

    2010-01-01

    Deep subwavelength integration of high-definition plasmonic nanostructures is of key importance for the development of future optical nanocircuitry for high-speed communication, quantum computation and lab-on-a-chip applications. So far the experimental realization of proposed extended plasmonic networks consisting of multiple functional elements remains challenging, mainly due to the multi-crystallinity of commonly used thermally evaporated gold layers. Resulting structural imperfections in individual circuit elements will drastically reduce the yield of functional integrated nanocircuits. Here we demonstrate the use of very large (>100 micron^2) but thin (<80 nm) chemically grown single-crystalline gold flakes, which, after immobilization, serve as an ideal basis for focused-ion beam milling and other top-down nanofabrication techniques on any desired substrate. Using this methodology we obtain high-definition ultrasmooth gold nanostructures with superior optical properties and reproducible nano-sized fe...

  3. Wet chemical deposition of single crystalline epitaxial manganite thin films with atomically flat surface

    International Nuclear Information System (INIS)

    We report the wet chemical deposition of single crystalline epitaxial thin films of the colossal magneto-resistive manganite La0.67Sr0.33MnO3 on the lattice-matched (001)-face of a La0.3Sr0.7Al0.65Ta0.35O3 substrate. Topographic images of these films taken with a scanning tunneling microscope show atomically flat terraces separated by steps of monatomic height. The resistivity of these films shows an insulator-metal transition at 310 K, nearly coincident with the Curie temperature of 340 K, found from magnetization measurements. The films show a magnetoresistance of 7% at 300 K and 1.2 T. Their saturation magnetization value at low temperatures is consistent with that of the bulk. - Highlights: ► Wet chemical deposition of La0.67Sr0.33MnO3 (LSMO) on a lattice-matched substrate. ► Single crystalline epitaxial LSMO films obtained. ► Flat terraces separated by monatomic steps observed by scanning tunneling microscope

  4. Single Crystalline Film of Hexagonal Boron Nitride Atomic Monolayer by Controlling Nucleation Seeds and Domains

    OpenAIRE

    Qinke Wu; Ji-Hoon Park; Sangwoo Park; Seong Jun Jung; Hwansoo Suh; Noejung Park; Winadda Wongwiriyapan; Sungjoo Lee; Young Hee Lee; Young Jae Song

    2015-01-01

    A monolayer hexagonal boron nitride (h-BN) film with controllable domain morphology and domain size (varying from less than 1 μm to more than 100 μm) with uniform crystalline orientation was successfully synthesized by chemical vapor deposition (CVD). The key for this extremely large single crystalline domain size of a h-BN monolayer is a decrease in the density of nucleation seeds by increasing the hydrogen gas flow during the h-BN growth. Moreover, the well-defined shape of h-BN flakes can ...

  5. Copper diffusion into single-crystalline TiN studied by transmission electron microscopy and atom probe tomography

    International Nuclear Information System (INIS)

    TiN/Cu bilayers were grown by unbalanced DC magnetron sputter deposition on (001)-oriented MgO substrates. Pole figures and electron back-scatter diffraction orientation maps indicate that both layers in the as-deposited state are single-crystalline with a cube-on-cube epitaxial relationship with the substrate. This is confirmed by selected area electron diffraction patterns. To study the efficiency of the TiN barrier layer against in-diffusion of Cu, we annealed samples at 900 °C for 1 h in vacuum and at 1000 °C for 12 h in Ar atmosphere. The single-crystalline structure of the TiN layer is stable up to annealing temperatures of 1000 °C as shown by high resolution transmission electron microscopy. While no Cu diffusion was evident after annealing at 900 °C, scanning transmission electron microscopy images and energy-dispersive X-ray spectrometry maps show a uniform diffusion layer of about 12 nm after annealing at 1000 °C for 12 h. Concentration depth profiles obtained from 3D atom probe tomography reconstructions confirm these findings and reveal that the TiN film is slightly substoichiometric with a N/Ti ratio of 0.92. Considering this composition, we propose a lattice diffusion mechanism of Cu in TiN via the formation of Cu–N vacancy complexes. The excellent diffusion barrier properties of single-crystalline TiN are further attributed to the lack of fast diffusion paths such as grain boundaries. - Highlights: • Sputter deposition of epitaxial, single-crystalline TiN/Cu bilayers on MgO (001) • Cu diffusion into TiN is studied by TEM and atom probe tomography. • No Cu diffusion is evident after annealing at 900 °C for 1 h. • After annealing at 1000 °C for 12 h a uniform diffusion layer of 12 nm is observed

  6. Preparation and Loading Process of Single Crystalline Samples into a Gas Environmental Cell Holder for In Situ Atomic Resolution Scanning Transmission Electron Microscopic Observation.

    Science.gov (United States)

    Straubinger, Rainer; Beyer, Andreas; Volz, Kerstin

    2016-06-01

    A reproducible way to transfer a single crystalline sample into a gas environmental cell holder for in situ transmission electron microscopic (TEM) analysis is shown in this study. As in situ holders have only single-tilt capability, it is necessary to prepare the sample precisely along a specific zone axis. This can be achieved by a very accurate focused ion beam lift-out preparation. We show a step-by-step procedure to prepare the sample and transfer it into the gas environmental cell. The sample material is a GaP/Ga(NAsP)/GaP multi-quantum well structure on Si. Scanning TEM observations prove that it is possible to achieve atomic resolution at very high temperatures in a nitrogen environment of 100,000 Pa. PMID:27026281

  7. Epitaxial growth of homogeneous single-crystalline AlN films on single-crystalline Cu (1 1 1) substrates

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Single-crystalline AlN films have been grown on single-crystalline Cu substrates. • High thickness homogeneity AlN films have been achieved. • Crack free AlN films have been grown single-crystalline Cu substrates. • The as-grown ∼321 nm thick AlN films are only with a compressive strain of 0.48%. - Abstract: The homogeneous and crack free single-crystalline AlN thin films have been epitaxially grown on single-crystalline Cu (1 1 1) substrates with an in-plane alignment of AlN [11–20]//Cu [1–10] by pulsed laser deposition (PLD) technology with an integrated laser rastering program. The as-grown AlN films are studied by spectroscopic ellipsometry, field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), polarized light microscopy, high-resolution X-ray diffraction, and high-resolution transmission electron microscopy (HRTEM). The spectroscopic ellipsometry reveals the excellent thickness uniformity of as-grown AlN films on the Cu (1 1 1) substrates with a root-mean-square (RMS) thickness inhomogeneity less than 2.6%. AFM and FESEM measurements indicate that very smooth and flat surface AlN films are obtained with a surface RMS roughness of 2.3 nm. The X-ray reflectivity image illustrates that there is a maximum of 1.2 nm thick interfacial layer existing between the as-grown AlN and Cu (1 1 1) substrates and is confirmed by HRTEM measurement, and reciprocal space mapping shows that almost fully relaxed AlN films are achieved only with a compressive strain of 0.48% within ∼321 nm thick films. This work demonstrates a possibility to obtain homogeneous and crack free single-crystalline AlN films on metallic substrates by PLD with optimized laser rastering program, and brings up a broad prospect for the application of acoustic filters that require abrupt hetero-interfaces between the AlN films and the metallic electrodes

  8. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, A.I.; Gargas, Daniel; Jeong Hwang, Yun; Yang, Peidong

    2009-08-04

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. These porous nanowires also retain the crystallographic orientation of the wafer from which they are etched. Electron microscopy and diffraction confirm their single-crystallinity and reveal the silicon surrounding the pores is as thin as several nanometers. Confocal fluorescence microscopy showed that the photoluminescence (PL) of these arrays emanate from the nanowires themselves, and their PL spectrum suggests that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices.

  9. A Single-Crystalline Mesoporous Quartz Superlattice.

    Science.gov (United States)

    Matsuno, Takamichi; Kuroda, Yoshiyuki; Kitahara, Masaki; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

    2016-05-10

    There has been significant interest in the crystallization of nanostructured silica into α-quartz because of its physicochemical properties. We demonstrate a single-crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α-quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li(+) only on the surface of silica nanospheres is effective for crystallization. PMID:27060365

  10. Single crystalline mesoporous silicon nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Hochbaum, Allon; Dargas, Daniel; Hwang, Yun Jeong; Yang, Peidong

    2009-08-18

    Herein we demonstrate a novel electroless etching synthesis of monolithic, single-crystalline, mesoporous silicon nanowire arrays with a high surface area and luminescent properties consistent with conventional porous silicon materials. The photoluminescence of these nanowires suggest they are composed of crystalline silicon with small enough dimensions such that these arrays may be useful as photocatalytic substrates or active components of nanoscale optoelectronic devices. A better understanding of this electroless route to mesoporous silicon could lead to facile and general syntheses of different narrow bandgap semiconductor nanostructures for various applications.

  11. Single-crystalline aluminum film for ultraviolet plasmonic nanolasers

    Science.gov (United States)

    Chou, Bo-Tsun; Chou, Yu-Hsun; Wu, Yen-Mo; Chung, Yi-Cheng; Hsueh, Wei-Jen; Lin, Shih-Wei; Lu, Tien-Chang; Lin, Tzy-Rong; Lin, Sheng-Di

    2016-01-01

    Significant advances have been made in the development of plasmonic devices in the past decade. Plasmonic nanolasers, which display interesting properties, have come to play an important role in biomedicine, chemical sensors, information technology, and optical integrated circuits. However, nanoscale plasmonic devices, particularly those operating in the ultraviolet regime, are extremely sensitive to the metal and interface quality. Thus, these factors have a significant bearing on the development of ultraviolet plasmonic devices. Here, by addressing these material-related issues, we demonstrate a low-threshold, high-characteristic-temperature metal-oxide-semiconductor ZnO nanolaser that operates at room temperature. The template for the ZnO nanowires consists of a flat single-crystalline Al film grown by molecular beam epitaxy and an ultrasmooth Al2O3 spacer layer synthesized by atomic layer deposition. By effectively reducing the surface plasmon scattering and metal intrinsic absorption losses, the high-quality metal film and the sharp interfaces formed between the layers boost the device performance. This work should pave the way for the use of ultraviolet plasmonic nanolasers and related devices in a wider range of applications.

  12. Atomically flat superconducting nanofilms: multiband properties and mean-field theory

    Science.gov (United States)

    Shanenko, A. A.; Aguiar, J. Albino; Vagov, A.; Croitoru, M. D.; Milošević, M. V.

    2015-05-01

    Recent progress in materials synthesis enabled fabrication of superconducting atomically flat single-crystalline metallic nanofilms with thicknesses down to a few monolayers. Interest in such nano-thin systems is attracted by the dimensional 3D-2D crossover in their coherent properties which occurs with decreasing the film thickness. The first fundamental aspect of this crossover is dictated by the Mermin-Wagner-Hohenberg theorem and concerns frustration of the long-range order due to superconductive fluctuations and the possibility to track its impact with an unprecedented level of control. The second important aspect is related to the Fabri-Pérot modes of the electronic motion strongly bound in the direction perpendicular to the nanofilm. The formation of such modes results in a pronounced multiband structure that changes with the nanofilm thickness and affects both the mean-field behavior and superconductive fluctuations. Though the subject is very rich in physics, it is scarcely investigated to date. The main obstacle is that there are no manageable models to study a complex magnetic response in this case. Full microscopic consideration is rather time consuming, if practicable at all, while the standard Ginzburg-Landau theory is not applicable. In the present work we review the main achievements in the subject to date, and construct and justify an efficient multiband mean-field formalism which allows for numerical and even analytical treatment of nano-thin superconductors in applied magnetic fields.

  13. Controlled synthesis of single-crystalline graphene

    Directory of Open Access Journals (Sweden)

    Wang Xueshen

    2014-02-01

    Full Text Available This paper reports the controlled synthesis of single-crystalline graphene on the back side of copper foil using CH4 as the precursor. The influence of growth time and the pressure ratio of CH4/H2 on the structure of graphene are examined. An optimized polymer-assisted method is used to transfer the synthesized graphene onto a SiO2/Si substrate. Scanning electron microscopy and Raman spectroscopy are used to characterize the graphene.

  14. Oriented single crystalline titanium dioxide nanowires

    International Nuclear Information System (INIS)

    We report the synthesis of oriented single crystalline titanium dioxide (TiO2) nanowire arrays on titanium foil. The synthesis method relies on the ability to grow single crystal sodium titanate (Na2Ti2O5·H2O) nanowires on titanium foil through a novel alkali hydrothermal growth process. Following growth, the Na2Ti2O5·H2O nanowires are converted to protonated bititanate (H2Ti2O5·H2O) nanowires through an ion-exchange reaction without changing their morphology or crystal structure. Finally, the protonated bititanate nanowires are converted to single crystalline anatase TiO2 nanowires through a topotactic transformation by calcination. These three sequential steps yield a carpet of 2-50 μm long single crystalline nanowires oriented in the [100] direction and primarily normal to the titanium foil. Even longer nanowires can be grown. The single crystal TiO2 nanowire arrays on flexible titanium substrate may be used in photocatalytic and photovoltaic devices such as dye-sensitized solar cells and may enhance their performance by providing fast electron transport. The nanowires can also be used as templates for producing hierarchical nanostructures such as nanowires decorated with nanoparticles on their periphery or nanotubes with walls made of nanoparticles.

  15. STM, SECPM, AFM and Electrochemistry on Single Crystalline Surfaces

    Directory of Open Access Journals (Sweden)

    Ulrich Stimming

    2010-08-01

    Full Text Available Scanning probe microscopy (SPM techniques have had a great impact on research fields of surface science and nanotechnology during the last decades. They are used to investigate surfaces with scanning ranges between several 100 mm down to atomic resolution. Depending on experimental conditions, and the interaction forces between probe and sample, different SPM techniques allow mapping of different surface properties. In this work, scanning tunneling microscopy (STM in air and under electrochemical conditions (EC-STM, atomic force microscopy (AFM in air and scanning electrochemical potential microscopy (SECPM under electrochemical conditions, were used to study different single crystalline surfaces in electrochemistry. Especially SECPM offers potentially new insights into the solid-liquid interface by providing the possibility to image the potential distribution of the surface, with a resolution that is comparable to STM. In electrocatalysis, nanostructured catalysts supported on different electrode materials often show behavior different from their bulk electrodes. This was experimentally and theoretically shown for several combinations and recently on Pt on Au(111 towards fuel cell relevant reactions. For these investigations single crystals often provide accurate and well defined reference and support systems. We will show heteroepitaxially grown Ru, Ir and Rh single crystalline surface films and bulk Au single crystals with different orientations under electrochemical conditions. Image studies from all three different SPM methods will be presented and compared to electrochemical data obtained by cyclic voltammetry in acidic media. The quality of the single crystalline supports will be verified by the SPM images and the cyclic voltammograms. Furthermore, an outlook will be presented on how such supports can be used in electrocatalytic studies.

  16. Nanomechanics of Single Crystalline Tungsten Nanowires

    Directory of Open Access Journals (Sweden)

    Volker Cimalla

    2008-01-01

    Full Text Available Single crystalline tungsten nanowires were prepared from directionally solidified NiAl-W alloys by a chemical release from the resulting binary phase material. Electron back scatter diffraction (EBSD proves that they are single crystals having identical crystallographic orientation. Mechanical investigations such as bending tests, lateral force measurements, and mechanical resonance measurements were performed on 100–300 nm diameter wires. The wires could be either directly employed using micro tweezers, as a singly clamped nanowire or in a doubly clamped nanobridge. The mechanical tests exhibit a surprisingly high flexibility for such a brittle material resulting from the small dimensions. Force displacement measurements on singly clamped W nanowires by an AFM measurement allowed the determination of a Young's modulus of 332 GPa very close to the bulk value of 355 GPa. Doubly clamped W nanowires were employed as resonant oscillating nanowires in a magnetomotively driven resonator running at 117 kHz. The Young's modulus determined from this setup was found to be higher 450 GPa which is likely to be an artefact resulting from the shift of the resonance frequency by an additional mass loading.

  17. Method for forming single phase, single crystalline 2122 BCSCO superconductor thin films by liquid phase epitaxy

    Science.gov (United States)

    Pandey, Raghvendra K. (Inventor); Raina, Kanwal (Inventor); Solayappan, Narayanan (Inventor)

    1994-01-01

    A substantially single phase, single crystalline, highly epitaxial film of Bi.sub.2 CaSr.sub.2 Cu.sub.2 O.sub.8 superconductor which has a T.sub.c (zero resistance) of 83 K is provided on a lattice-matched substrate with no intergrowth. This film is produced by a Liquid Phase Epitaxy method which includes the steps of forming a dilute supercooled molten solution of a single phase superconducting mixture of oxides of Bi, Ca, Sr, and Cu having an atomic ratio of about 2:1:2:2 in a nonreactive flux such as KCl, introducing the substrate, e.g., NdGaO.sub.3, into the molten solution at 850.degree. C., cooling the solution from 850.degree. C. to 830.degree. C. to grow the film and rapidly cooling the substrate to room temperature to maintain the desired single phase, single crystalline film structure.

  18. A single crystalline InP nanowire photodetector

    Science.gov (United States)

    Yan, Xin; Li, Bang; Wu, Yao; Zhang, Xia; Ren, Xiaomin

    2016-08-01

    Single crystalline nanowires are critical for achieving high-responsivity, high-speed, and low-noise nanoscale photodetectors. Here, we report a metal-semiconductor-metal photodetector based on a single crystalline InP nanowire. The nanowires are grown by a self-catalyzed method and exhibit stacking-fault-free zinc blende crystal structure. The nanowire exhibits a typical n-type semiconductor property and shows a low room temperature dark current of several hundred pA at moderate biases. A photoresponsivity of 6.8 A/W is obtained at a laser power density of 0.2 mW/cm2. This work demonstrates that single crystalline InP nanowires are good candidates for future optoelectronic device applications.

  19. The Atomic Views of Flat Supply Chains in China

    Directory of Open Access Journals (Sweden)

    Sekhar Chattopadhyay

    2010-09-01

    Full Text Available China's domestic supply chain networks are getting flat and unbalanced despite its spectacular growth and rise to the enviable position in the global supply chain arena in recent times. The aftermath of continued investment explosion, especially in the coastal areas of the mainland, calls for an interwoven relationship of Chinese companies with the rest of the global supply chains. However, with new information and communication technologies, the real-time problems arising from this flattened supply chains are much more complex, multifaceted and multidimensional. China needs to re-think and re-focus on better alignment to the western values and cultures while managing its global business activities. This paper discusses four recently developed enterprise models in the light of several case studies conducted recently in Australia, China and India to characterise these new flat supply chains: People-Centric, Molecular Organization, Globally Dispersed and Disaggregated Value Chain. These, apparently different but inherently similar models have a vibrant architecture and system behaviour in their core and propose an alternative approach to address challenges of unbalanced domestic flat supply chains in China and helps the Chinese manufacturers to explore an approach to embrace Western values and cultures by enlarging their sphere of influence.

  20. Controlling growth density and patterning of single crystalline silicon nanowires

    International Nuclear Information System (INIS)

    This study examines the usage of well-patterned Au nanoparticles (NPs) as a catalyst for one-dimensional growth of single crystalline Si nanowires (NWs) through the vapor-liquid-solid (VLS) mechanism. The study reports the fabrication of monolayer Au NPs through the self-assembly of Au NPs on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. Results indicate that the spin coating time of Au NPs plays a crucial role in determining the density of Au NPs on the surface of the silicon substrate and the later catalysis growth of Si NWs. The experiments in this study employed optical lithography to pattern Au NPs, treating them as a catalyst for Si NW growth. The patterned Si NW structures easily produced and controlled Si NW density. This approach may be useful for further studies on single crystalline Si NW-based nanodevices and their properties.

  1. Subsurface damage of single crystalline silicon carbide in nanoindentation tests.

    Science.gov (United States)

    Yan, Jiwang; Gai, Xiaohui; Harada, Hirofumi

    2010-11-01

    The response of single crystalline silicon carbide (SiC) to a Berkovich nanoindenter was investigated by examining the indents using a transmission electron microscope and the selected area electron diffraction technique. It was found that the depth of indentation-induced subsurface damage was far larger than the indentation depth, and the damaging mechanism of SiC was distinctly different from that of single crystalline silicon. For silicon, a broad amorphous region is formed underneath the indenter after unloading; for SiC, however, no amorphous phase was detected. Instead, a polycrystalline structure with a grain size of ten nanometer level was identified directly under the indenter tip. Micro cracks, basal plane dislocations and possible cross slips were also found around the indent. These finding provide useful information for ultraprecision manufacturing of SiC wafers. PMID:21138038

  2. Electric dipolar interaction assisted growth of single crystalline organic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jin-ming, Cai [Material Science and Technology Division, Oak Ridge National Laboratory; Yu-Yang, Zhang [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Hao, Hu [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Li-Hong, Bao [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Li-Da, Pan [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Wei, Tang [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Guo, Li [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Shi-Xuan, Du [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Jian, Shen [Material Science and Technology Division, Oak Ridge National Laboratory; Hong-Jun, Gao [Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

    2010-01-01

    We report on a forest-like-to-desert-like pattern evolution in the growth of an organic thin film observed by using an atomic force microscope. We use a modified diffusion limited aggregation model to simulate the growth process and are able to reproduce the experimental patterns. The energy of electric dipole interaction is calculated and determined to be the driving force for the pattern formation and evolution. Based on these results, single crystalline films are obtained by enhancing the electric dipole interaction while limiting effects of other growth parameters.

  3. Magnetisation curves of single-crystalline Tb2Fe17

    International Nuclear Information System (INIS)

    Magnetisation measurements in fields up to 38 T have been performed on single-crystalline Tb2Fe17 at 4.2 K. Tb2Fe17 is confirmed to be an easy-plane ferrimagnet. Along the hard c-axis a transition is observed at 3.9 T. The data have been analysed within a one- and a two-sublattice model. (orig.)

  4. Single Crystalline CVD Diamond Based Devices for Power Electronics Applications

    OpenAIRE

    Adrian, Ehrnebo

    2014-01-01

    Chemical vapor deposited single-crystalline diamond has rare material properties such as thermal conductivity five times as high as copper, a wide band gap, a high breakdown field and high carrier mobilities. This makes it a very interesting material for high power, high frequency and high temperature applications. In this thesis work, metal oxide semiconductor (MOS) capacitors of diamond substrate were fabricated and analyzed. The MOS capacitor is a building block of the metal oxide semicond...

  5. Observation of superconductivity in single crystalline Bi nanowires

    International Nuclear Information System (INIS)

    Bi nanowires have been fabricated by electrochemical deposition into the pores of ion track etched polycarbonate membranes. Transmission electron microscopy and selected area electron diffraction measurements reveal that these Bi nanowires are single crystalline with the rhombohedral lattice structure of bulk Bi at ambient pressure. We have measured the temperature dependence of the resistance and I-V characteristics at various magnetic fields on these Bi nanowires. These measurements show clear evidence for superconductivity below 0.64 K

  6. Freestanding single-crystalline magnetic structures fabricated by ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Schoenherr, P.; Bischof, A.; Boehm, B.; Eib, P.; Grimm, S.; Gross, L.; Allenspach, R., E-mail: ral@zurich.ibm.com [IBM Research – Zurich, 8803 Rüschlikon (Switzerland); Alvarado, S. F. [Department of Materials, ETH Zürich, 8093 Zürich (Switzerland)

    2015-01-19

    Starting from an ultrathin Fe film grown epitaxially on top of a GaAs(001) substrate, we show that freestanding structures can be created by ion-beam treatment. These structures are single-crystalline blisters and only a few nanometers thick. Anisotropic stress in the rim of a blister induces magnetic domain states magnetized in the direction normal to the blister edge. Experimental evidence is provided that the lateral size can be confined by starting from a nanostructured template.

  7. Development of novel UV emitting single crystalline film scintillators

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Gorbenko, V.; Nikl, Martin; Mareš, Jiří A.; Martin, T.; Douissard, P.-A.

    2010-01-01

    Roč. 57, č. 3 (2010), s. 1335-1342. ISSN 0018-9499 R&D Projects: GA ČR GA202/08/0893 Institutional research plan: CEZ:AV0Z10100521 Keywords : Ce 3+ * garnet and perovskite compounds * La 3+ and Sc 3+ dopants * liquid phase epitaxy method * Pr 3+ * single crystalline film scintillators * UV luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.519, year: 2010

  8. Synthesis and characterization of single crystalline selenium nanowire arrays

    International Nuclear Information System (INIS)

    Ordered selenium nanowire arrays with diameters about 40 nm have been fabricated by electrodeposition using anodic porous alumina templates. As determined by X-ray diffraction, Raman spectra, electron diffraction and high-resolution transmission electron microscopy, selenium nanowires have uniform diameters, which are fully controllable. Single crystalline trigonal selenium nanowires have been obtained after postannealing at 180 deg. C. These nanowires are perfect with a c-axis growth orientation. The optical absorption spectra reveal two types of electron transition activity

  9. Preparing arrays of large atomically flat regions on single crystal substrates

    International Nuclear Information System (INIS)

    We report a simple and general procedure to create arrays of atomically flat terraces on single crystal surfaces. Facets of three-dimensional (3D) metal islands formed after hetero-epitaxial growth are often flat and, through annealing or growth at elevated temperature, the formation of rather large (micron-scale) atomically flat-top facets can be promoted. We find that the step-free nature of top facets on such islands can be transferred to the substrate surface through room-temperature ion-sputter etching, followed by an annealing step. We use low-energy electron microscopy (LEEM) and Auger electron spectroscopy (AES) for in situ monitoring of the process steps while fabricating arrays of step-free surface regions on W(110), Ru(0001), Cu(100), and Fe(100) single crystals.

  10. Electroanalytical performance of carbon films with near-atomic flatness.

    Science.gov (United States)

    Ranganathan, S; McCreery, R L

    2001-03-01

    Physicochemical and electrochemical characterization of carbon films obtained by pyrolyzing a commercially available photoresist has been performed. Photoresist spin-coated on to a silicon wafer was pyrolyzed at 1,000 degrees C in a reducing atmosphere (95% nitrogen and 5% hydrogen) to produce conducting carbon films. The pyrolyzed photoresist films (PPF) show unusual surface properties compared to other carbon electrodes. The surfaces are nearly atomically smooth with a root-mean-square roughness of pyrolysis to evaluate the electroanalytical utility of PPF. Heterogeneous electron-transfer kinetics of various redox systems were evaluated. For Ru(NH3)6(3+/2+), Fe(CN)6(3-/4-), and chlorpromazine, fresh PPF surfaces show electron-transfer rates similar to those on GC, but for redox systems such as Fe3+/2+, ascorbic acid, dopamine, and oxygen, the kinetics on PPF are slower. Very weak interactions between the PPF surface and these redox systems lead to their slow electron-transfer kinetics. Electrochemical anodization results in a simultaneous increase in background current, adsorption, and electron-transfer kinetics. The PPF surfaces can be chemically modified via diazonium ion reduction to yield a covalently attached monolayer. Such a modification could help in the preparation of low-cost, high-volume analyte-specific electrodes for diverse electroanalytical applications. Overall, pyrolysis of the photoresist yields an electrode surface with properties similar to a very smooth version of glassy carbon, with some important differences in surface chemistry. PMID:11289433

  11. Single crystalline ultrathin gold nanowires: Promising nanoscale interconnects

    Directory of Open Access Journals (Sweden)

    Ahin Roy

    2013-03-01

    Full Text Available Using first principles based density functional calculation we study the mechanical, electronic and transport properties of single crystalline gold nanowires. While nanowires with the diameter less than 2 nm retain hexagonal cross-section, the larger diameter wires show a structural smoothening leading to circular cross-section. These structural changes significantly affect the mechanical properties of the wires, however, strength remains comparable to the bulk. The transport calculations reveal that the conductivity of these wires are in good agreement with experiments. The combination of good mechanical, electronic and transport properties make these wires promising as interconnects for nano devices.

  12. Atomically flat reconstructed rutile TiO2(001) surfaces for oxide film growth

    Science.gov (United States)

    Wang, Y.; Lee, S.; Vilmercati, P.; Lee, H. N.; Weitering, H. H.; Snijders, P. C.

    2016-02-01

    The availability of low-index rutile TiO2 single crystal substrates with atomically flat surfaces is essential for enabling epitaxial growth of rutile transition metal oxide films. The high surface energy of the rutile (001) surface often leads to surface faceting, which precludes the sputter and annealing treatment commonly used for the preparation of clean and atomically flat TiO2(110) substrate surfaces. In this work, we reveal that stable and atomically flat rutile TiO2(001) surfaces can be prepared with an atomically ordered reconstructed surface already during a furnace annealing treatment in air. We tentatively ascribe this result to the decrease in surface energy associated with the surface reconstruction, which removes the driving force for faceting. Despite the narrow temperature window where this morphology can initially be formed, we demonstrate that it persists in homoepitaxial growth of TiO2(001) thin films. The stabilization of surface reconstructions that prevent faceting of high-surface-energy crystal faces may offer a promising avenue towards the realization of a wider range of high quality epitaxial transition metal oxide heterostructures.

  13. Periodic magnetic domains in single-crystalline cobalt filament arrays

    Science.gov (United States)

    Chen, Fei; Wang, Fan; Jia, Fei; Li, Jingning; Liu, Kai; Huang, Sunxiang; Luan, Zhongzhi; Wu, Di; Chen, Yanbin; Zhu, Jianmin; Peng, Ru-Wen; Wang, Mu

    2016-02-01

    Magnetic structures with controlled domain wall pattern may be applied as potential building blocks for three-dimensional magnetic memory and logic devices. Using a unique electrochemical self-assembly method, we achieve regular single-crystalline cobalt filament arrays with specific geometric profile and crystallographic orientation, and the magnetic domain configuration can be conveniently tailored. We report the transition of periodic antiparallel magnetic domains to compressed vortex magnetic domains depending on the ratio of height to width of the wires. A "phase diagram" is obtained to describe the dependence of the type of magnetic domain and the geometrical profiles of the wires. Magnetoresistance of the filaments demonstrates that the contribution of a series of 180∘ domain walls is over 0.15 % of the zero-field resistance ρ (H =0 ) . These self-assembled magnetic nanofilaments, with controlled periodic domain patterns, offer an interesting platform to explore domain-wall-based memory and logic devices.

  14. Electron microscope observation of single - crystalline beryllium thin foils

    International Nuclear Information System (INIS)

    Thin foils prepared from single crystalline beryllium simples deformed at room temperature, have been observed by transmission electron microscopy. The various deformation modes have been investigated separately, from their early stages and their characteristic dislocation configurations have been observed. Basal slip is characterized at is outset by the presence of numerous dipoles and elongated prismatic loops. More pronounced cold work leads to the formation of dislocation tangles and bundles which eventually give a cellular structure. Prismatic slip begins by the cross-slip of dislocations from the basal plane into the prismatic plane. A cellular structure is equally observed in heavily deformed samples. Sessile dislocations have been observed in twin boundaries; they are produced by reactions between slip dislocations and twin dislocations. Finally, the study of samples quenched from 1100 deg. C and annealed at 200 deg. C has shown that the observed loops lie in prismatic planes and have a Burgers vector b 1/3. (authors)

  15. Synthesis and characterization of single-crystalline alumina nanowires

    Institute of Scientific and Technical Information of China (English)

    ZHAO Qing; XU Xiang-yu; ZHANG Hong-zhou; CHEN Yao-feng; XU Jun; YU Da-peng

    2005-01-01

    Alumina nanowires were synthesized on large-area silicon substrate via simple thermal evaporation method of heating a mixture of aluminum and alumina powders without using any catalyst or template. The phase structure and the surface morphology of the as-grown sample were analyzed by X-ray diffractometry(XRD) and scanning electron microscopy (SEM), respectively. The chemical composition and the microstructure of the as-grown alumina nanowires were characterized using transmission electron microscope(TEM). The nanowires are usually straight and the single crystalline has average diameter of 40 nm and length of 3 - 5 μm. The growth direction is along the [002] direction. Well aligned alumina nanowire arrays were observed on the surface of many large particles. The catalyst-free growth of the alumina nanowires was explained under the framework of a vapor-solid(VS)growth mechanism. This as-synthesized alumina nanowires could find potential applications in the fabrication of nanodevices.

  16. Cold welding of copper nanowires with single-crystalline and twinned structures: A comparison study

    Science.gov (United States)

    Huang, Rao; Shao, Gui-Fang; Wen, Yu-Hua

    2016-09-01

    In this article, molecular simulations were adopted to explore the cold welding processes of copper nanowires with both single-crystalline and fivefold twinned structures. It was verified that the twinned nanowires exhibited enhanced strength but lowered elastic limit and ductility. Both nanowires could be successfully welded through rather small loadings, although their stress-strain responses toward compression were different. Meanwhile, more stress was accumulated in the twinned nanowire due to repulsive force of the twin boundaries against the nucleation and motions of dislocations. Moreover, by characterizing the structure evolutions in the welding process, it can be ascertained that perfect atomic order was finally built at the weld region in both nanowires. This comparison study will be of great importance to future mechanical processing of metallic nanowires.

  17. Nanoscale mechanical surface properties of single crystalline martensitic Ni-Mn-Ga ferromagnetic shape memory alloys

    International Nuclear Information System (INIS)

    Located beyond the resolution limit of nanoindentation, contact resonance atomic force microscopy (CR-AFM) is employed for nano-mechanical surface characterization of single crystalline 14M modulated martensitic Ni-Mn-Ga (NMG) thin films grown by magnetron sputter deposition on (001) MgO substrates. Comparing experimental indentation moduli-obtained with CR-AFM-with theoretical predictions based on density functional theory (DFT) indicates the central role of pseudo plasticity and inter-martensitic phase transitions. Spatially highly resolved mechanical imaging enables the visualization of twin boundaries and allows for the assessment of their impact on mechanical behavior at the nanoscale. The CR-AFM technique is also briefly reviewed. Its advantages and drawbacks are carefully addressed. (paper)

  18. Self-controlled fabrication of single-crystalline silicon nanobeams using conventional micromachining.

    Science.gov (United States)

    Mehdizadeh, Emad; Rahafrooz, Amir; Pourkamali, Siavash

    2014-08-01

    This paper reports on a low-cost top-down approach to the nano-precision fabrication of nanobeams on single-crystalline silicon using only conventional micromachining technology. The fabrication technique takes advantage of the crystalline structure of silicon for controllable feature size reduction of nanobeams with atomically smooth surfaces and sharp edges. Applying a deliberate rotational misalignment in a 2 μm resolution standard lithography process, followed by anisotropic wet etching of the silicon, nanobeams with well uniform widths as small as ∼85 nm are fabricated on thin SOI substrates. As a proof of concept for the incorporation of such nanobeams within electromechancial structures, we successfully demonstrate thermally actuated resonators that show very high frequencies (close to 50 MHz). PMID:25036338

  19. Self-controlled fabrication of single-crystalline silicon nanobeams using conventional micromachining

    International Nuclear Information System (INIS)

    This paper reports on a low-cost top-down approach to the nano-precision fabrication of nanobeams on single-crystalline silicon using only conventional micromachining technology. The fabrication technique takes advantage of the crystalline structure of silicon for controllable feature size reduction of nanobeams with atomically smooth surfaces and sharp edges. Applying a deliberate rotational misalignment in a 2 μm resolution standard lithography process, followed by anisotropic wet etching of the silicon, nanobeams with well uniform widths as small as ∼85 nm are fabricated on thin SOI substrates. As a proof of concept for the incorporation of such nanobeams within electromechancial structures, we successfully demonstrate thermally actuated resonators that show very high frequencies (close to 50 MHz). (paper)

  20. Development of novel UV emitting single crystalline film scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu; Gorbenko, V; Savchyn, V; Voznyak, T [Laboratory of Opoelectronic Materials (LOM), Electronics Department of Ivan Franko National University of Lviv, 79017 Lviv (Ukraine); Nikl, M; Mares, J A [Institute of Physics of ASCR, 162 53 Prague (Czech Republic); Martin, T; Douissard, P-A, E-mail: zorenko@electronics.wups.lviv.ua [ESRF, Instrument Support Group, 6 rue Jules Horoeitz, 38043 Grenoble (France)

    2011-04-01

    The work is dedicated to development of new types of UV -emitting scintillators based on single crystalline films (SCF) of aluminium perovskites and garnets grown by the liquid phase epitaxy (LPE) method. The development of the following three types of UV SCF scintillators is considered in this work: i) Ce-doped SCF of Y-Lu-Al-perovskites with Ce{sup 3+} emission in the 360-370 nm range with a decay time of 16-17 ns; ii) Pr-doped SCF of Y-Lu-Al garnets with Pr{sup 3+} emission in the 300-400 nm range with a decay time of 13-17 ns; iii) La{sup 3+} and Sc{sup 3+} doped SCF of Y-Lu-Al-garnets, emitting in the 290-400 nm range due to formation of the La{sub Y,Lu}, Sc{sub Y,Lu} and Sc{sub Al} centers with decay time of 250-575 ns. The results of testing the several novel UV-emitting SCFs scintillators for visualization of X-ray images at ESFR are presented. It is shown that the UV emission of the LuAG:Sc, LuAG:La and LuAG:Pr SCFs is efficient enough for conversion of X-ray to the UV light and that these scintillators can be used for improvement of the resolution of imaging detectors in synchrotron radiation applications.

  1. Synthesis and Characterization of Atomically Flat Methyl-Terminated Ge(111) Surfaces

    OpenAIRE

    Wong, Keith T.; Kim, Youn-Geun; Soriaga, Manuel P.; Brunschwig, Bruce S.; Lewis, Nathan S.

    2015-01-01

    Atomically flat, terraced H–Ge(111) was prepared by annealing in H_2(g) at 850 °C. The formation of monohydride Ge–H bonds oriented normal to the surface was indicated by angle-dependent Fourier-transform infrared (FTIR) spectroscopy. Subsequent reaction in CCl_3Br(l) formed Br-terminated Ge(111), as shown by the disappearance of the Ge–H absorption in the FTIR spectra concomitant with the appearance of Br photoelectron peaks in X-ray photoelectron (XP) spectra. The Br–Ge(111) surface was met...

  2. Flat metallic surface gratings with sub-10 nm gaps controlled by atomic-layer deposition

    Science.gov (United States)

    Chen, Borui; Ji, Dengxin; Cheney, Alec; Zhang, Nan; Song, Haomin; Zeng, Xie; Thomay, Tim; Gan, Qiaoqiang; Cartwright, Alexander

    2016-09-01

    Atomic layer lithography is a recently reported new technology to fabricate deep-subwavelength features down to 1–2 nm, based on combinations of electron beam lithography (EBL) and atomic layer deposition (ALD). However, the patterning area is relatively small as limited by EBL, and the fabrication yield is not very high due to technical challenges. Here we report an improved procedure to fabricate flat metallic surfaces with sub-10 nm features based on ALD processes. To demonstrate the scalability of the new manufacturing method, we combine the ALD process with large area optical interference patterning, which is particularly promising for the development of practical applications for nanoelectronics and nanophotonics with extremely strong confinement of electromagnetic fields.

  3. Synthesis and Characterization of Atomically Flat Methyl-Terminated Ge(111) Surfaces.

    Science.gov (United States)

    Wong, Keith T; Kim, Youn-Geun; Soriaga, Manuel P; Brunschwig, Bruce S; Lewis, Nathan S

    2015-07-22

    Atomically flat, terraced H-Ge(111) was prepared by annealing in H2(g) at 850 °C. The formation of monohydride Ge-H bonds oriented normal to the surface was indicated by angle-dependent Fourier-transform infrared (FTIR) spectroscopy. Subsequent reaction in CCl3Br(l) formed Br-terminated Ge(111), as shown by the disappearance of the Ge-H absorption in the FTIR spectra concomitant with the appearance of Br photoelectron peaks in X-ray photoelectron (XP) spectra. The Br-Ge(111) surface was methylated by reaction with (CH3)2Mg. These surfaces exhibited a peak at 568 cm(-1) in the high-resolution electron energy loss spectrum, consistent with the formation of a Ge-C bond. The absorption peaks in the FTIR spectra assigned to methyl "umbrella" and rocking modes were dependent on the angle of the incident light, indicating that the methyl groups were bonded directly atop surface Ge atoms. Atomic-force micrographs of CH3-Ge(111) surfaces indicated that the surface remained atomically flat after methylation. Electrochemical scanning-tunneling microscopy showed well-ordered methyl groups that covered nearly all of the surface. Low-energy electron diffraction images showed sharp, bright diffraction spots with a 3-fold symmetry, indicating a high degree of order with no evidence of surface reconstruction. A C 1s peak at 284.1 eV was observed in the XP spectra, consistent with the formation of a C-Ge bond. Annealing in ultrahigh vacuum revealed a thermal stability limit of ∼400 °C of the surficial CH3-Ge(111) groups. CH3-Ge(111) surfaces showed significantly greater resistance to oxidation in air than H-Ge(111) surfaces. PMID:26154680

  4. Control growth of single crystalline ZnO nanorod arrays and nanoflowers with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Feng Jiuju [College of Geography and Environmental Science, Zhejiang Normal University (China); Wang Zhenzhen [School of Chemistry and Chemical Engineering, Henan Normal University (China); Li Yongfang [College of Chemistry and Chemical Engineering, Henan Institute of Science and Technology (China); Chen Jianrong; Wang Aijun, E-mail: ajwang@zjnu.cn [College of Geography and Environmental Science, Zhejiang Normal University (China)

    2013-04-15

    Single crystalline vertical nanorod arrays and nanoflowers of ZnO have been grown in situ on cheap zinc foils under hydrothermal conditions, by means of hexamethylenetetramine and ethanolamine, respectively. Their morphologies and crystal structures are characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The nanorods and flowers of ZnO grew along the {l_brace} 10 1-bar 1{r_brace} and {l_brace} 0001{r_brace} planes, respectively. Both types of ZnO display high photocatalytic ability toward the degradation of methylene orange under UV irradiation. The ZnO nanorods show better performance than that of the ZnO nanoflowers, and the {l_brace} 10 1-bar 1{r_brace} facets of the ZnO nanorods have higher photoactivity than that of the {l_brace} 000 1-bar {r_brace} or {l_brace} 10 1-bar 0{r_brace} crystal planes. This is because the weaker coordinated O atoms on the surface are more likely to be saturated by H atoms in aqueous solution, thereby releasing more free OH radicals.Graphical AbstractA facile method was developed for selective control synthesis of ZnO nanoflowers and nanorod arrays on Zinc foil, with the assistance of ethanolamine and the hexamethylenetetramine, respectively. The illustration shows the time evolution of the two ZnO structures.

  5. Control growth of single crystalline ZnO nanorod arrays and nanoflowers with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Single crystalline vertical nanorod arrays and nanoflowers of ZnO have been grown in situ on cheap zinc foils under hydrothermal conditions, by means of hexamethylenetetramine and ethanolamine, respectively. Their morphologies and crystal structures are characterized by X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The nanorods and flowers of ZnO grew along the { 10 1-bar 1} and { 0001} planes, respectively. Both types of ZnO display high photocatalytic ability toward the degradation of methylene orange under UV irradiation. The ZnO nanorods show better performance than that of the ZnO nanoflowers, and the { 10 1-bar 1} facets of the ZnO nanorods have higher photoactivity than that of the { 000 1-bar } or { 10 1-bar 0} crystal planes. This is because the weaker coordinated O atoms on the surface are more likely to be saturated by H atoms in aqueous solution, thereby releasing more free OH radicals.Graphical AbstractA facile method was developed for selective control synthesis of ZnO nanoflowers and nanorod arrays on Zinc foil, with the assistance of ethanolamine and the hexamethylenetetramine, respectively. The illustration shows the time evolution of the two ZnO structures.

  6. Growth and characterization of single crystalline Ga-doped ZnO films using rf magnetron sputtering

    International Nuclear Information System (INIS)

    In this article it is shown that high quality single crystalline Ga-doped ZnO (GZO) films could be achieved on ac-plane sapphire using conventional rf magnetron sputtering. High-resolution x-ray diffractometry, transmission electron microscopy (TEM), and scanning electron microscopy investigations clearly confirmed that the GZO films with low Ga doping levels up to 1wt% were of high quality single crystal, which is featured by the (0002) rocking curve as narrow as 0.14 deg., symmetric six poles in pole figure, sharply defined spot pattern in the TEM diffraction diagram of the interfacial region, and the flat surface. It was also estimated from the Hall measurements and photoluminescence spectroscopy that these single crystalline GZO films possessed good optical and electrical characteristics including the narrow band-width and higher intensity of exciton-related emission peak, Hall mobility as large as 66 cm2 V-1 s-1, and the resistivity as low as 1.69 x 10-3 Ω cm

  7. Growth and characterization of single crystalline Ga-doped ZnO films using rf magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung-Teak [Department of Materials Science and Engineering, Photonic and Electronic Thin Film Laboratory, Chonnam National University, 300 Yong-bong dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Kim, Tae-Hwan [Department of Materials Science and Engineering, Photonic and Electronic Thin Film Laboratory, Chonnam National University, 300 Yong-bong dong, Buk-gu, Gwangju 500-757 (Korea, Republic of); Jeong, Sang-Hun [Gwangju Center, Korea Basic Science Institute, 300 Yong-bong dong, Buk-gu, Gwangju 500-757 (Korea, Republic of)

    2006-03-07

    In this article it is shown that high quality single crystalline Ga-doped ZnO (GZO) films could be achieved on ac-plane sapphire using conventional rf magnetron sputtering. High-resolution x-ray diffractometry, transmission electron microscopy (TEM), and scanning electron microscopy investigations clearly confirmed that the GZO films with low Ga doping levels up to 1wt% were of high quality single crystal, which is featured by the (0002) rocking curve as narrow as 0.14 deg., symmetric six poles in pole figure, sharply defined spot pattern in the TEM diffraction diagram of the interfacial region, and the flat surface. It was also estimated from the Hall measurements and photoluminescence spectroscopy that these single crystalline GZO films possessed good optical and electrical characteristics including the narrow band-width and higher intensity of exciton-related emission peak, Hall mobility as large as 66 cm{sup 2} V{sup -1} s{sup -1}, and the resistivity as low as 1.69 x 10{sup -3} {omega} cm.

  8. Single crystalline film screens for cathode-ray tubes: New life of television scanning optical microscopy

    International Nuclear Information System (INIS)

    Advantages of television scanning optical microscopy are discussed in comparison with cameral microscopy. Peculiarities of new types of cathode-ray tubes with single crystalline film screens, as a source of scanning beam, are described

  9. Variations in Crystalline Structures and Electrical Properties of Single Crystalline Boron Nitride Nanosheets.

    Science.gov (United States)

    Aldalbahi, Ali; Zhou, Andrew Feng; Feng, Peter

    2015-01-01

    We report the studies of (1) the basic mechanism underlying the formation of defect-free, single crystalline boron nitride nanosheets (BNNSs) synthesized using pulsed laser plasma deposition (PLPD) technique, (2) the variation in the crystalline structure at the edges of the hexagonal boron nitride (h-BN) nanosheets, and (3) the basic electrical properties related to the BNNSs tunneling effect and electrical breakdown voltage. The nanoscale morphologies of BNNSs are characterized using scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM). The results show that each sample consisted of a number of transparent BNNSs that partially overlapped one another. Varying the deposition duration yielded different thicknesses of sample but did not affect the morphology, structure, and thickness of individual BNNSs pieces. Analysis of the SEM and HRTEM data revealed changes in the spatial period of the B3-N3 hexagonal structures and the interlayer distance at the edge of the BNNSs, which occurred due to the limited number of atomic layers and was confirmed further by x-ray diffraction (XRD) study. The experimental results clearly indicate that the values of the electrical conductivities of the super-thin BNNSs and the effect of temperature relied strongly on the direction of observation. PMID:26563901

  10. Equilibrium segregation of sulfur to the free surface of single crystalline titanium

    International Nuclear Information System (INIS)

    Equilibrium segregation of sulfur to the free surface of single crystalline titanium from 560 deg. C to 800 deg. C was investigated using Auger electron spectroscopy (AES) measurements. To describe the concentration evolution in the sulfur overlayer, Fick's first law was modified by adding a local function df(x)/dx, to the concentration gradient to drive the segregation starting from an initially homogeneous distribution. The diffusion equation thus derived was solved for the case f(x)=asexp (-x/ds). It was found that the solution leads to an AES intensity evolution for segregants, IS(t)=IS∞ (1-eα erfc((α)1/2)), α=Dt/ds2, which fits the experimental results extremely well. An exponentially decaying distribution of sulfur beneath the titanium surface at equilibrium was revealed by sputter depth profiling, which in turn justifies our modification to Fick's first law. Without referring to the detailed kinetics, an activation energy Ea =718 meV/atom was determined by comparing the sulfur concentration evolution at different temperatures. (author)

  11. Preparation of highly ordered growth of single-crystalline Gd2O2S:Eu3+ nanostructures

    International Nuclear Information System (INIS)

    Graphical abstract: Fabrication of highly ordered single-crystalline Gd2O2S:Eu3+ nanostructures over a porous anodized aluminum oxide (AAO) template via hydrothermal method is described. Well aligned non-collapsed Gd2O2S:Eu3+ nanostructures are ideal functional components for next generation luminescent devices. Research highlights: → Synthesis of highly ordered Gd2O2S:Eu3+ nanotubes, nanorods and nanoflowers. → Using template-assisted (AAO) hydrothermal method. → Well aligned nanostructures for next generation luminescent devices. → Detailed structural, morphology and the phase composition were studied. -- Abstract: A simple and facile template-assisted hydrothermal route has been demonstrated for the shape-selective preparation of highly ordered single-crystalline Gd2O2S:Eu3+ nanostructures, such as nanotubes, nanorods and nanoflowers. These fabricated nanostructures possess desirable atomic structures, surfaces, morphologies and properties to meet the growing demands and specific requirements of new technologies. The concentration of precursor chemicals, the temperature, the reaction time, and the use of a capping agent are key factors in the morphological control of Gd2O2S:Eu3+ nanostructures. The morphology and the phase composition of the prepared nanostructures were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy disperse spectroscopy (EDS) and photoluminescence (PL). We believe this technique will be readily adopted in realizing other forms of various nanostructured materials.

  12. Modulation-doped growth of mosaic graphene with single-crystalline p-n junctions for efficient photocurrent generation

    Science.gov (United States)

    Yan, Kai; Wu, Di; Peng, Hailin; Jin, Li; Fu, Qiang; Bao, Xinhe; Liu, Zhongfan

    2012-12-01

    Device applications of graphene such as ultrafast transistors and photodetectors benefit from the combination of both high-quality p- and n-doped components prepared in a large-scale manner with spatial control and seamless connection. Here we develop a well-controlled chemical vapour deposition process for direct growth of mosaic graphene. Mosaic graphene is produced in large-area monolayers with spatially modulated, stable and uniform doping, and shows considerably high room temperature carrier mobility of ~5,000 cm2 V-1 s-1 in intrinsic portion and ~2,500 cm2 V-1 s-1 in nitrogen-doped portion. The unchanged crystalline registry during modulation doping indicates the single-crystalline nature of p-n junctions. Efficient hot carrier-assisted photocurrent was generated by laser excitation at the junction under ambient conditions. This study provides a facile avenue for large-scale synthesis of single-crystalline graphene p-n junctions, allowing for batch fabrication and integration of high-efficiency optoelectronic and electronic devices within the atomically thin film.

  13. High carrier mobility in chemically modified graphene on an atomically flat high-resistive substrate

    International Nuclear Information System (INIS)

    Special high-resistive substrates for graphene sheets are suggested with the aim of providing high conductivity and mobility of charge carriers in graphene. The substrates were created from N-methylpyrrolidone-intercalated few-layer graphene (FLG) using anneals given to FLG samples in the temperature range 100–180 °C. Structures containing a highly conductive single-layer graphene on an atomically flat, high-resistive substrate were produced by recovering the top-layer conductivity. The obtained structures have potential in electronic applications due to a high carrier mobility (up to 16 000–42 000 cm2 V−1 s−1) and strong gate-voltage-induced modulation (by 4–5 orders of magnitude) of the current in the top graphene layer. The strong gate-voltage-induced modulation of the current clearly demonstrated that the top layer was chemically modified graphene. The possibility of governing the surface conductivity in the described structures offers a unique tool for two-dimensional nanodesign. (paper)

  14. Preparation of atomically flat TiO2(001) surfaces

    Science.gov (United States)

    Wang, Yang; Weitering, Hanno H.; Snijders, Paul C.

    2015-03-01

    Transition metal oxides with the rutile structure (MO2, M = e.g. Ti, V, or Nb) have highly directional partially occupied t2g orbitals. Some of these orbitals form quasi-1D electronic bands along the rutile c-axis, and Peierls-like ordering phenomena have been observed in VO2 and NbO2. Tailoring the electronic properties of these materials via quantum confinement requires epitaxial growth on suitable substrates such as low index TiO2 surfaces. Because of the high surface energy of rutile TiO2(001), the standard approach of sputtering and annealing usually introduces faceting. Here we demonstrate a facile method to create atomically flat, non-faceted TiO2(001) surfaces. Using scanning tunneling microscopy we observe terraces with a width of approximately 150 nm. Step heights of approximately 0.3 nm are observed, consistent with the c lattice parameter of rutile TiO2. Low energy electron diffraction patterns reveal sharp diffraction spots with an in-plane lattice constant of 0.358 nm which is consistent with a (1x1) ordering of the (001) plane. These TiO2(001) single crystal surfaces can serve as an ideal substrate for further growth of rutile heterostructures. Research sponsored by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  15. On crystallization of polypropylene on atomically flat silicate substrate and relationship to mechanical properties

    International Nuclear Information System (INIS)

    Research highlights: → Phyllosilicate was used to probe the nucleation and chain organization in thin films. → Crystal morphology was altered from leaf-like structure to fully developed spherulites. → The lamellae structure changed from well-oriented to cross-hatched implying epitaxial growth. → The good interfacial bonding favored by epitaxial crystallization is beneficial for toughness. - Abstract: Phyllosilicates including mica offer one of the easiest methods to obtain atomically flat surface of macroscopic size by cleavage. Thus, thin films of polypropylene crystallized at different pressure and as a function of polypropylene concentration were investigated. The objective was to probe the nucleation and chain organization in thin films on basal plane surface from the view point of relating the nucleation and growth process to the intergallery space between the clay layers. The crystal morphology was altered from leaf-like structure at high undercooling to fully developed spherulites at low undercooling. Furthermore, the lamellae structure change from well-oriented to cross-hatched with increase in the crystallization pressure was indicative of epitaxial growth between polymer matrix and mica surface. The possible epitaxial mechanism is discussed here. The study provides a method to explore the macro- and microstructure of polymer and epitaxy between polymer matrix and inorganic particle surface. The good interfacial bonding favored by epitaxial crystallization is beneficial for toughness.

  16. Advanced fabrication of single-crystalline silver nanopillar on SiO2 substrate

    International Nuclear Information System (INIS)

    Nanoscale crystallographic textures have received very little attention in research on surface plasmons using metallic nanostructures. A single-crystalline metallic nanostructure with a controlled crystallographic texture is expected to reduce optical losses. We elucidated the grain growth mechanism in silver thin films deposited on a highly transparent SiO2 substrate by electron backscatter diffraction methods with nanoscale resolution. At higher substrate temperatures, the grain growth was facilitated but the preferred orientation was not achieved. Moreover, we fabricated a single-crystalline silver nanopillar in a (111)-oriented large growing grain, which was controlled by varying the substrate temperature during film deposition by focused ion-beam milling. Furthermore, the light intensity of the scattering spectrum was measured for a single-crystalline silver nanopillar (undersurface diameter: 200 nm) for which surface plasmon resonance was observed. The single-crystalline silver nanopillar exhibits a stronger and sharper spectrum than the polycrystalline silver nanopillar. These results can be applied to the direct fabrication of a single-crystalline silver nanopillar using only physical processing

  17. Advanced fabrication of single-crystalline silver nanopillar on SiO{sub 2} substrate

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Tomohiro, E-mail: tomohiro-mori@wakayama-kg.jp, E-mail: kenzo@eng.kagawa-u.ac.jp [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, Hayashicho 2217-20, Takamatsu, Kagawa 761-0396 (Japan); Industrial Technology Center of Wakayama Prefecture, Ogura 60, Wakayama 649-6261 (Japan); Tanaka, Yasuhiro; Suzaki, Yoshifumi; Yamaguchi, Kenzo, E-mail: tomohiro-mori@wakayama-kg.jp, E-mail: kenzo@eng.kagawa-u.ac.jp [Department of Advanced Materials Science, Faculty of Engineering, Kagawa University, Hayashicho 2217-20, Takamatsu, Kagawa 761-0396 (Japan)

    2016-01-25

    Nanoscale crystallographic textures have received very little attention in research on surface plasmons using metallic nanostructures. A single-crystalline metallic nanostructure with a controlled crystallographic texture is expected to reduce optical losses. We elucidated the grain growth mechanism in silver thin films deposited on a highly transparent SiO{sub 2} substrate by electron backscatter diffraction methods with nanoscale resolution. At higher substrate temperatures, the grain growth was facilitated but the preferred orientation was not achieved. Moreover, we fabricated a single-crystalline silver nanopillar in a (111)-oriented large growing grain, which was controlled by varying the substrate temperature during film deposition by focused ion-beam milling. Furthermore, the light intensity of the scattering spectrum was measured for a single-crystalline silver nanopillar (undersurface diameter: 200 nm) for which surface plasmon resonance was observed. The single-crystalline silver nanopillar exhibits a stronger and sharper spectrum than the polycrystalline silver nanopillar. These results can be applied to the direct fabrication of a single-crystalline silver nanopillar using only physical processing.

  18. Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate

    Science.gov (United States)

    Choi, Sang; King, Glen; Park, Yeonjoon

    2009-01-01

    SiGe is an important semiconductor alloy for high-speed field effect transistors (FETs), high-temperature thermoelectric devices, photovoltaic solar cells, and photon detectors. The growth of SiGe layer is difficult because SiGe alloys have different lattice constants from those of the common Si wafers, which leads to a high density of defects, including dislocations, micro-twins, cracks, and delaminations. This innovation utilizes newly developed rhombohedral epitaxy of cubic semiconductors on trigonal substrates in order to solve the lattice mismatch problem of SiGe by using trigonal single crystals like sapphire (Al2O3) as substrate to give a unique growth-orientation to the SiGe layer, which is automatically controlled at the interface upon sapphire (0001). This technology is different from previous silicon on insulator (SOI) or SGOI (SiGe on insulator) technologies that use amorphous SiO2 as the growth plane. A cubic semiconductor crystal is a special case of a rhombohedron with the inter-planar angle, alpha = 90 deg. With a mathematical transformation, all rhombohedrons can be described by trigonal crystal lattice structures. Therefore, all cubic lattice constants and crystal planes (hkl) s can be transformed into those of trigonal crystal parameters. These unique alignments enable a new opportunity of perfect lattice matching conditions, which can eliminate misfit dislocations. Previously, these atomic alignments were thought to be impossible or very difficult. With the invention of a new x-ray diffraction measurement method here, growth of cubic semiconductors on trigonal crystals became possible. This epitaxy and lattice-matching condition can be applied not only to SiGe (111)/sapphire (0001) substrate relations, but also to other crystal structures and other materials, including similar crystal structures which have pointgroup rotational symmetries by 120 because the cubic (111) direction has 120 rotational symmetry. The use of slightly miscut (less than

  19. Solution-phase synthesis of single-crystalline Fe3O4 magnetic nanobelts

    International Nuclear Information System (INIS)

    Single-crystalline Fe3O4 nanobelt was first synthesized on a large scale by a facile and efficient hydrothermal process. The samples were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). The SAED pattern obtained from a typical individual nanobelt has a highly symmetrical dotted lattice, which reveals the single-crystalline nature of belt-like Fe3O4. The saturation magnetization of the Fe3O4 nanobelt is higher than the wire, hollow sphere and octahedral structure. Such methods are easy and mild, and could synthesize other metal oxide in such experiment situation

  20. Fabrication of Single Crystalline silicon on Glass by Smart-Cut Technique

    Institute of Scientific and Technical Information of China (English)

    SONG Hua-Qing; SHI Jing; ZHANG Miao; LIN Qing; LIN Cheng-Lu

    2003-01-01

    Single crystalline silicon films are transferred on to a glass substrate by the smart-cut technique, which is based on fT*~ ions implantation, anodic bonding and layer transfer. Structures of the resulting thin film silicon on glass (SOG) are characterized by transmission-electron microscopy, scanning electron microscopy and Raman spectroscopy. The results show that SOG substrates fabricated by the smart-cut have advantages of steep top Si/glass interface and good monocrystalline Si quality. The Hall-effect measurement indicates that the single crystalline SOG substrates have a better electrical property compared with polycrystalline silicon SOG substrates.

  1. Single-crystalline AlN growth on sapphire using physical vapor deposition

    International Nuclear Information System (INIS)

    A novel technique for growing single crystalline aluminum nitride (AlN) films is presented. The novelty of the technique, specifically, comes from the use of an innovative physical vapor deposition magnetron sputtering tool, which embeds magnets into the target material. A relatively high deposition rates is achieved (∼0.2 μm/min), at temperatures between 860 and 940 oC. The AlN, grown onto sapphire, is single-crystalline as evidenced by observation using transmission electron microscopy. Tool configuration and growth conditions are discussed, as well as a first set of other analytical results, namely, x-ray diffraction and ultraviolet-visible transmission spectrophotometry.

  2. Wurtzite-type faceted single-crystalline GaN nanotubes

    Science.gov (United States)

    Liu, Baodan; Bando, Yoshio; Tang, Chengchun; Shen, Guozhen; Golberg, Dmitri; Xu, Fangfang

    2006-02-01

    We report on the direct fabrication of single-crystalline wurtzite-type hexagonal GaN nanotubes via a newly designed, controllable, and reproducible chemical thermal-evaporation process. The nanotubes are single crystalline, have one end closed, an average outer diameter of ˜300nm, an inner diameter of ˜100nm, and a wall thickness of ˜100nm. The structure and morphology of the tubes are characterized using a scanning electron microscope and a transmission electron microscope. The cathodoluminescence of individual nanotubes is also investigated. The growth mechanism, formation kinetics, and crystallography of GaN nanotubes are finally discussed.

  3. Pop-in effect in Ge and Si coated single-crystalline Si

    International Nuclear Information System (INIS)

    Complete text of publication follows. Silicon is one of the most important elements in contemporary times. Its central role in semiconductor industry makes all of its properties important. Consequently even its mechanical properties gain wide attention in the research community. Additionally, silicon shows a series of very interesting pressure-dependent phase transformations, drawing even more attention to this field. More than twelve stable and metastable solid phases have been observed, which are arising at high pressure by increasing or decreasing hydrostatic stress. Nanoindentation or depth sensing indentation is often used for studying local mechanical properties, because it is in many cases the only method providing results from the small volume considered, and because of the simplicity of the test. As result of the phase transformation caused by the pressure increase during loading of the indenter a discontinuity (a 'pop-in' effect) can occur in the load curve, represented by a horizontal line (or an elbow), pointing to larger penetration depth. Similarly during unloading of the indenter a second discontinuity (a 'pop-out' effect) can occur, represented by a horizontal line (or an elbow), pointing to shallower depths. In this study single-crystalline silicon substrates covered by amorphous Si and Ge layer, produced by magnetron sputtering, were nanoindented by different types of indenter (Berkovich, cube corner and spherical indenters), to investigate the effect of these coatings on the pop-in and pop-out effects. It has been investigated 20-, 50-, 100-, 150 nm thick layers of amorphous Si and Ge in single- and in multiple load events. The impressions caused by the indentation were imaged by atomic force microscopy (AFM). Our experiments provide a consistent evaluation of the Young's modulus and hardness of the samples and consistent data on the exact shape of the indent impressions. The measured elastic modulus shows a slight decrease of both properties due

  4. Local Weak Ferromagnetism in Single-Crystalline Ferroelectric BiFeO3

    DEFF Research Database (Denmark)

    Ramazanoglu, M.; Laver, Mark; Ratcliff, W.; Watson, S.M.; Chen, W.C.; Jackson, A.; Kothapalli, K.; Lee, S.; Cheong, S.-W.; Kiryukhin, V.

    2011-01-01

    Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO3 reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic...

  5. Magneto-acoustic study of single crystalline UCu.sub.0.95./sub.Ge

    Czech Academy of Sciences Publication Activity Database

    Yasin, S.; Andreev, Alexander V.; Skourski, Y.; Wosnitza, J.; Zherlitsyn, S.; Zvyagin, A.A.

    2011-01-01

    Roč. 83, č. 13 (2011), "134401-1"-"134401-5". ISSN 1098-0121 R&D Projects: GA ČR GA202/09/0339 Institutional research plan: CEZ:AV0Z10100520 Keywords : single crystalline * magneto -acoustic study * pronounced anomalies Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  6. Elastic properties of single-crystalline and consolidated nano-structured yttrium oxide at room temperature

    International Nuclear Information System (INIS)

    High resolution Brillouin spectroscopy was used to characterize the elastic stiffness properties of consolidated nano-crystalline yttrium oxide as well as of the related single-crystalline state. Defect enriched grain boundaries are discussed as sources for the extremely soft elastic properties of the nano-crystalline state. (author)

  7. Controllable growth of ultrathin BiFeO3 from finger-like nanostripes to atomically flat films

    Science.gov (United States)

    Feng, Yu; Wang, Can; Tian, Shilu; Zhou, Yong; Ge, Chen; Guo, Haizhong; He, Meng; Jin, Kuijuan; Yang, Guozhen

    2016-09-01

    BiFeO3 (BFO) ultrathin films with nominal thicknesses from 2 to 12 nm were grown with a SrRuO3 (SRO) buffer layer on TiO2-terminated (001) SrTiO3 (STO) substrates using pulsed laser deposition. The surface morphologies and domain configurations of the thin films were investigated using atomic force microscopy and piezoelectric force microscopy. Periodical one-dimensional finger-like nanostripes of BFO on the SRO covered STO substrates were observed. With increasing thickness, the BFO ultrathin films develop from the finger-like nanostripes to an atomically flat surface. The formation of the finger-like nanostructures of BFO is related to the atomic step or terrace structure of the substrate. The BFO nanostripes and the atomically flat thin films both show good ferroelectricity. The as-grown domain orientations of the BFO ultrathin films are ascribed to the chemical terminations at the surface of the SRO layer. These results indicate that the surface morphologies and the domain configurations of BFO ultrathin films can be artificially designed by using substrates with optimized terrace structures and chemical termination, and these films are potentially useful in multifunctional nanoelectronic devices.

  8. Single-Crystalline SrRuO3 Nanomembranes: A Platform for Flexible Oxide Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Fong, Dillon D.; Paskiewicz, Deborah M.; Sichel-Tissot, Rebecca; Stan, Liliana; Karapetrova, Evguenia

    2016-01-01

    The field of oxide electronics has benefited from the wide spectrum of functionalities available to the ABO3 perovskites, and researchers are now employing defect engineering in single crystalline heterostructures to tailor properties. However, bulk oxide single crystals are not conducive to many types of applications, particularly those requiring mechanical flexibility. Here, we demonstrate the realization of an all-oxide, single-crystalline nanomembrane heterostructure. With a surface-to-volume ratio of 2 × 107 , the nanomembranes are fully flexible and can be readily transferred to other materials for handling purposes or for new materials integration schemes. Using in situ synchrotron X-ray scattering, we find that the nanomembranes can bond to other host substrates near room temperature and demonstrate coupling between surface reactivity and electromechanical properties in ferroelectric nanomembrane systems. The synthesis technique described here represents a significant advancement in materials integration and provides a new platform for the development of flexible oxide electronics.

  9. Proton irradiation effects on thermal transport in individual single-crystalline Bi nanowires

    International Nuclear Information System (INIS)

    We investigated the proton irradiation effect of thermal conductivities for individual single-crystalline Bi nanowires grown by the on-film formation of nanowires (ON-OFF). The thermal conductivities of Bi nanowires with diameter of 154 and 112 nm were measured using suspended devices before and after proton irradiation, respectively. It was founded thermal conductivities of Bi nanowires appreciably decrease after proton irradiation, which was caused by the destruction of single-crystallinity due to the high-energy proton impingement. This result indicates the defects of Bi nanowires created by proton drastically limit the mean free paths of phonons, resulting in the change of thermal transport of Bi nanowires. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Single crystalline graphene synthesized by thermal annealing of humic acid over copper foils

    Science.gov (United States)

    Beall, Gary W.; Duraia, El-Shazly M.; Yu, Q.; Liu, Z.

    2014-02-01

    Production of graphene by thermal annealing on copper foil substrates has been studied with different sources of carbon. The three carbon sources include humic acid derived from leonardite, graphenol, and activated charcoal. Hexagonal single crystalline graphene has been synthesized over the copper foil substrates by thermal annealing of humic acid, derived from leonardite, in argon and hydrogen atmosphere (Ar/H2=20). The annealing temperature was varied between 1050 °C and 1100 °C at atmospheric pressure. Samples have been investigated using scanning electron microscope (SEM) and Raman spectroscopy. At lower temperatures the thermal annealing of the three carbon sources used in this study produces pristine graphene nanosheets which cover almost the whole substrate. However when the annealing temperature has been increased up to 1100 °C, hexagonal single crystalline graphene have been observed only in the case of the humic acid. Raman analysis showed the existence of 2D band around 2690 cm-1.

  11. Investigation of the nonlinear refractive index of single-crystalline thin gold films and plasmonic nanostructures

    Science.gov (United States)

    Goetz, Sebastian; Razinskas, Gary; Krauss, Enno; Dreher, Christian; Wurdack, Matthias; Geisler, Peter; Pawłowska, Monika; Hecht, Bert; Brixner, Tobias

    2016-04-01

    The nonlinear refractive index of plasmonic materials may be used to obtain nonlinear functionality, e.g., power-dependent switching. Here, we investigate the nonlinear refractive index of single-crystalline gold in thin layers and nanostructures on dielectric substrates. In a first step, we implement a z-scan setup to investigate ~100-µm-sized thin-film samples. We determine the nonlinear refractive index of fused silica, n 2(SiO2) = 2.9 × 10-20 m2/W, in agreement with literature values. Subsequent z-scan measurements of single-crystalline gold films reveal a damage threshold of 0.22 TW/cm2 and approximate upper limits of the real and imaginary parts of the nonlinear refractive index, | n 2'(Au)| crystalline gold film). An upper limit for the nonlinear power-dependent phase change between two propagating near-field modes is determined to Δ φ < 0.07 rad.

  12. Magnetisation curves of single-crystalline Tb sub 2 Fe sub 17

    Energy Technology Data Exchange (ETDEWEB)

    Verhoef, R.; Quang, P.H.; Radwanski, R.J.; Marquina, C.; Franse, J.J.M. (Van der Waals-Zeeman Lab., Univ. van Amsterdam (Netherlands))

    1992-02-01

    Magnetisation measurements in fields up to 38 T have been performed on single-crystalline Tb{sub 2}Fe{sub 17} at 4.2 K. Tb{sub 2}Fe{sub 17} is confirmed to be an easy-plane ferrimagnet. Along the hard c-axis a transition is observed at 3.9 T. The data have been analysed within a one- and a two-sublattice model. (orig.).

  13. Experimental measurement of Young’s modulus from a single crystalline cementite

    International Nuclear Information System (INIS)

    Pure Fe–C pearlite was heat-treated and selectively etched to extract [0 0 1]- and [1 0 0]-oriented single crystalline cementite sheets. The elastic properties of the shaped cementite were measured in a simple, in situ bending test system set up inside the scanning electron microscope using a micronewton-range force sensor. The Young’s modulus experimentally measured from a single crystal sheet was lower than the value obtained from theoretical calculation

  14. Single-crystalline ZnO sheet Source-Gated Transistors

    OpenAIRE

    Dahiya, A. S.; Opoku, C.; Sporea,R.A.; Sarvankumar, B.; G. Poulin-Vittrant; F. Cayrel; Camara, N.; D. Alquier

    2016-01-01

    Due to their fabrication simplicity, fully compatible with low-cost large-area device assembly strategies, source-gated transistors (SGTs) have received significant research attention in the area of high-performance electronics over large area low-cost substrates. While usually based on either amorphous or polycrystalline silicon (α-Si and poly-Si, respectively) thin-film technologies, the present work demonstrate the assembly of SGTs based on single-crystalline ZnO sheet (ZS) with asymmetric...

  15. Self-powered cardiac pacemaker enabled by flexible single crystalline PMN-PT piezoelectric energy harvester.

    Science.gov (United States)

    Hwang, Geon-Tae; Park, Hyewon; Lee, Jeong-Ho; Oh, SeKwon; Park, Kwi-Il; Byun, Myunghwan; Park, Hyelim; Ahn, Gun; Jeong, Chang Kyu; No, Kwangsoo; Kwon, HyukSang; Lee, Sang-Goo; Joung, Boyoung; Lee, Keon Jae

    2014-07-23

    A flexible single-crystalline PMN-PT piezoelectric energy harvester is demonstrated to achieve a self-powered artificial cardiac pacemaker. The energy-harvesting device generates a short-circuit current of 0.223 mA and an open-circuit voltage of 8.2 V, which are enough not only to meet the standard for charging commercial batteries but also for stimulating the heart without an external power source. PMID:24740465

  16. Novel UV-emitting single crystalline film phosphors grown by LPE method

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Nikl, Martin; Mareš, Jiří A.; Winnacker, A.

    2010-01-01

    Roč. 45, 3-6 (2010), 444-448. ISSN 1350-4487 R&D Projects: GA ČR GA202/08/0893 Institutional research plan: CEZ:AV0Z10100521 Keywords : UV luminescence * single crystalline film * liquid phase epitaxy * garnets and perovskites * Ce 3+ * Pr 3+ * La 3+ * Sc 3+ * Bi 3+ dopants Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.019, year: 2010

  17. Aerosol-Assisted Synthesis of Monodisperse Single-Crystalline α-Cristobalite Nanospheres

    OpenAIRE

    Jiang, Xingmao; Bao, Lihong; Cheng, Yung-Sung; Dunphy, Darren R.; Li, Xiaodong; Brinker, C. Jeffrey

    2011-01-01

    Monodisperse single-crystalline α-cristobalite nanospheres have been synthesized by hydrocarbon-pyrolysis-induced carbon deposition on amorphous silica aerosol nanoparticles, devitrification of the coated silica at high temperature, and subsequent carbon removal by oxidation. The nanosphere size can be well controlled by tuning the size of the colloidal silica precursor. Uniform, high-purity nanocrystalline α-cristobalite is important for catalysis, nanocomposites, advanced polishing, and und...

  18. Solution coating of large-area organic semiconductor thin films with aligned single-crystalline domains

    KAUST Repository

    Diao, Ying

    2013-06-02

    Solution coating of organic semiconductors offers great potential for achieving low-cost manufacturing of large-area and flexible electronics. However, the rapid coating speed needed for industrial-scale production poses challenges to the control of thin-film morphology. Here, we report an approach - termed fluid-enhanced crystal engineering (FLUENCE) - that allows for a high degree of morphological control of solution-printed thin films. We designed a micropillar-patterned printing blade to induce recirculation in the ink for enhancing crystal growth, and engineered the curvature of the ink meniscus to control crystal nucleation. Using FLUENCE, we demonstrate the fast coating and patterning of millimetre-wide, centimetre-long, highly aligned single-crystalline organic semiconductor thin films. In particular, we fabricated thin films of 6,13-bis(triisopropylsilylethynyl) pentacene having non-equilibrium single-crystalline domains and an unprecedented average and maximum mobilities of 8.1±1.2 cm2 V-1 s -1 and 11 cm2 V-1 s-1. FLUENCE of organic semiconductors with non-equilibrium single-crystalline domains may find use in the fabrication of high-performance, large-area printed electronics. © 2013 Macmillan Publishers Limited. All rights reserved.

  19. FY 1997 report on the study on the formation condition of hetero-structure of single-crystalline semiconductor thin films; 1997 nendo chosa hokokusho (tankessho no handotai usumaku hetero kozo no keisei joken ni kansuru kenkyu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Since ion implantation causes material degradation by formation of crystalline defects, and hydrogen embrittlement deteriorates material strength, reduction of such defects has been positively studied. Study was made on a new active application of hydrogen separation into ion implantation defects. After H ion implantation of a proper depth into single-crystalline Si and SiC and successive annealing, single-crystalline films of sub-micron to several micron thick were obtained by hydrogen-induced delamination at the implantation depth due to hydrogen embrittlement in crystalline defects. The implantation depth is dependent on implantation energy. H atom forms (111) face defect through connection with dangling bond of crystalline defects. This crystal face defect forms a delamination plane through (100) face cleavage. This hydrogen embrittlement delamination by ion implantation is applicable to production of light-weight high-efficiency single-crystalline Si solar cells, and large single-crystalline SiC wafers as new resource saving process. 33 refs., 19 figs., 2 tabs.

  20. Local Weak Ferromagnetism in Single-Crystalline Ferroelectric BiFeO3

    OpenAIRE

    Ramazanoglu, M.; Laver, Mark; Ratcliff, W.; Watson, S. M.; Chen, W. C.; Jackson, A; Kothapalli, K.; Lee, S; Cheong, S.-W.; Kiryukhin, V.

    2011-01-01

    Polarized small-angle neutron scattering studies of single-crystalline multiferroic BiFeO3 reveal a long-wavelength spin density wave generated by ∼1° spin canting of the spins out of the rotation plane of the antiferromagnetic cycloidal order. This signifies weak ferromagnetism within mesoscopic regions of dimension 0.03 microns along [11̅ 0], to several microns along [111], confirming a long-standing theoretical prediction. The average local magnetization is 0.06  μB/Fe. Our results provide...

  1. Theory of phase transformation and reorientation in single crystalline shape memory alloys

    International Nuclear Information System (INIS)

    A constitutive model, based on an (n+1)-phase mixture of the Mori–Tanaka average theory, has been developed for stress-induced martensitic transformation and reorientation in single crystalline shape memory alloys. Volume fractions of different martensite lattice correspondence variants are chosen as internal variables to describe microstructural evolution. Macroscopic Gibbs free energy for the phase transformation is derived with thermodynamics principles and the ensemble average method of micro-mechanics. The critical condition and the evolution equation are proposed for both the phase transition and reorientation. This model can also simulate interior hysteresis loops during loading/unloading by switching the critical driving forces when an opposite transition takes place

  2. Thin-film transistor fabricated in single-crystalline transparent oxide semiconductor.

    Science.gov (United States)

    Nomura, Kenji; Ohta, Hiromichi; Ueda, Kazushige; Kamiya, Toshio; Hirano, Masahiro; Hosono, Hideo

    2003-05-23

    We report the fabrication of transparent field-effect transistors using a single-crystalline thin-film transparent oxide semiconductor, InGaO3(ZnO)5, as an electron channel and amorphous hafnium oxide as a gate insulator. The device exhibits an on-to-off current ratio of approximately 106 and a field-effect mobility of approximately 80 square centimeters per volt per second at room temperature, with operation insensitive to visible light irradiation. The result provides a step toward the realization of transparent electronics for next-generation optoelectronics. PMID:12764192

  3. Size-dependent magnetic properties of single-crystalline multiferroic BiFeO3 nanoparticles.

    Science.gov (United States)

    Park, Tae-Jin; Papaefthymiou, Georgia C; Viescas, Arthur J; Moodenbaugh, Arnold R; Wong, Stanislaus S

    2007-03-01

    As-prepared, single-crystalline bismuth ferrite nanoparticles show strong size-dependent magnetic properties that correlate with: (a) increased suppression of the known spiral spin structure (period length of approximately 62 nm) with decreasing nanoparticle size and (b) uncompensated spins and strain anisotropies at the surface. Zero-field-cooled and field-cooled magnetization curves exhibit spin-glass freezing behavior due to a complex interplay between finite size effects, interparticle interactions, and a random distribution of anisotropy axes in our nanoparticle assemblies. PMID:17324002

  4. Morphology and magnetic flux distribution in superparamagnetic, single-crystalline Fe3O4 nanoparticle rings

    International Nuclear Information System (INIS)

    This study reports on the correlation between crystal orientation and magnetic flux distribution of Fe3O4 nanoparticles in the form of self-assembled rings. High-resolution transmission electron microscopy demonstrated that the nanoparticles were single-crystalline, highly monodispersed, (25 nm average diameter), and showed no appreciable lattice imperfections such as twins or stacking faults. Electron holography studies of these superparamagnetic nanoparticle rings indicated significant fluctuations in the magnetic flux lines, consistent with variations in the magnetocrystalline anisotropy of the nanoparticles. The observations provide useful information for a deeper understanding of the micromagnetics of ultrasmall nanoparticles, where the magnetic dipolar interaction competes with the magnetic anisotropy.

  5. Field emission from single-crystalline CeB_6 nanowires

    Institute of Scientific and Technical Information of China (English)

    赵彦明; 欧阳柳生; 邹春云; 许军旗; 董有忠; 范庆华

    2010-01-01

    We presented a field electron emission measurement of single crystalline CeB6 nanowires.The nanowires exhibited a low turn-on electric field(7.6 V/μm at 10 μA/cm2),and the deviation of Fowler-Nordheim(F-N) plots from straight line was observed in field electron emission measurements.The field enhancement factors were obtained by separate straight line fitting.The nonlinearity in the F-N plots may be attributed to the non-uniform field electron emission of CeB6 nanowires.The field emission properties of the ...

  6. The recombination channels of luminescence excitation in YAG:Yb single crystalline films

    International Nuclear Information System (INIS)

    Absorption and emission spectra, luminescence decay kinetics and thermostimulated luminescence of X-ray irradiated YAG:Yb single crystalline films were studied. Two emission bands peaked at 420 and 488 nm have been detected in the investigated films. The strong thermal quenching of luminescence band at 488 nm was observed above 160 K. The influence of growth conditions and annealing in air on the lifetime of Yb3+ ion excited state in the IR spectral region have been revealed. The recombination mechanisms of the f-f transition at Yb3+ ion excitation, as well as the mechanism of lifetime shortening for the excited Yb3+ luminescence have been discussed

  7. Magnetic anisotropy of the single-crystalline ferromagnetic insulator Cr2Ge2Te6

    Science.gov (United States)

    Zhang, Xiao; Zhao, Yuelei; Song, Qi; Jia, Shuang; Shi, Jing; Han, Wei

    2016-03-01

    Cr2Ge2Te6 (CGT), a layered ferromagnetic insulator, has attracted a great deal of interest recently owing to its potential for integration with Dirac materials to realize the quantum anomalous Hall effect (QAHE) and to develop novel spintronics devices. Here, we study the uniaxial magnetic anisotropy energy of single-crystalline CGT and determine that the magnetic easy axis is directed along the c-axis in its ferromagnetic phase. In addition, CGT is an insulator below the Curie temperature. These properties make CGT a potentially promising candidate substrate for integration with topological insulators for the realization of the high-temperature QAHE.

  8. Machining with micro-size single crystalline diamond tools fabricated by a focused ion beam

    International Nuclear Information System (INIS)

    A study was carried out to understand the physics of micro-scale mechanical machining (henceforth referred to as 'micro-machining') with a micro-size tool using a five-axis ultra-precision machine. A micro-size single crystalline diamond (SCD) tool with sharp cutting edges fabricated by a focused ion beam (FIB) was employed to orthogonal-machine four materials (three polycrystalline metals with various grain sizes and one amorphous metal plating material). Since the wealth of knowledge of macro-machining cannot be successfully used in micro-machining, this study contributes to the understanding of the physics of mechanical machining with micro-size tools

  9. Photoinduced magnetic effects in bulk single-crystalline, polycrystalline, and LPE films of Yttrium Iron Garnet

    Science.gov (United States)

    Hisatake, K.; Matsubara, I.; Maeda, K.; Fujiwara, T.; Peters, M.; Abe, S.; Kudo, K.; Kainuma, S.; Tamaki, T.; Kino, Y.; de Francisco, C.; Munoz, J. M.; Alejos, O.; Hernandez, P.; Torres, C.; Shinagawa, K.

    2002-05-01

    The effect of light on magnetic initial permeability (the so-called photomagnetic effect) and photoinduced disaccommodation were studied in samples of yttrium iron garnet over the temperature range 77-300 K. The samples studied were bulk crystalline, produced by the floating zone method and the flux method, polycrystalline, produced by the usual sintering method, and single-crystalline films, produced by in situ liquid-phase epitaxis. One or both of the studied phenomena were observed in our experimental samples. To explain the experimental results, we suggest there is photoinduced structural distortion around oxygen vacancies due to a photoinduced change of charge imbalance.

  10. Characterization and Optical Properties of the Single Crystalline SnS Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Yue GH

    2009-01-01

    Full Text Available Abstract The SnS nanowire arrays have been successfully synthesized by the template-assisted pulsed electrochemical deposition in the porous anodized aluminum oxide template. The investigation results showed that the as-synthesized nanowires are single crystalline structures and they have a highly preferential orientation. The ordered SnS nanowire arrays are uniform with a diameter of 50 nm and a length up to several tens of micrometers. The synthesized SnS nanowires exhibit strong absorption in visible and near-infrared spectral region and the direct energy gapE gof SnS nanowires is 1.59 eV.

  11. Statistical theory of the boundary friction of atomically flat solid surfaces in the presence of a lubricant layer

    International Nuclear Information System (INIS)

    A rheological model and a thermodynamic model are proposed for describing the melting of an ultrathin lubricant film between atomically flat solid surfaces. Hysteresis phenomena are considered, allowing for the stress and strain dependence of the lubricant shear modulus. The self-similar regime of lubricant melting is studied taking the additive noncorrelated noise of basic parameters into account. The regions of dry, sliding, and stick-slip friction are determined in the phase diagram. Shear stress time series are obtained by numerically analyzing the Langevin equation and are then subjected to multifractal fluctuation analysis. The dependence of the stationary friction force on the lubricant temperature and on the shear velocity of rubbing surfaces is investigated. (reviews of topical problems)

  12. Single-layer MoS2 roughness and sliding friction quenching by interaction with atomically flat substrates

    International Nuclear Information System (INIS)

    We experimentally study the surface roughness and the lateral friction force in single-layer MoS2 crystals deposited on different substrates: SiO2, mica, and hexagonal boron nitride (h-BN). Roughness and sliding friction measurements are performed by atomic force microscopy. We find a strong dependence of the MoS2 roughness on the underlying substrate material, being h-BN the substrate which better preserves the flatness of the MoS2 crystal. The lateral friction also lowers as the roughness decreases, and attains its lowest value for MoS2 flakes on h-BN substrates. However, it is still higher than for the surface of a bulk MoS2 crystal, which we attribute to the deformation of the flake due to competing tip-to-flake and flake-to-substrate interactions

  13. Single-layer MoS{sub 2} roughness and sliding friction quenching by interaction with atomically flat substrates

    Energy Technology Data Exchange (ETDEWEB)

    Quereda, J. [Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049 (Spain); Castellanos-Gomez, A. [Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft (Netherlands); Agraït, N. [Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049 (Spain); Instituto Madrileño de Estudios Avanzados en Nanociencia, IMDEA-Nanociencia, E-28049 Madrid (Spain); Instituto de Ciencia de Materiales Nicolás Cabrera, Campus de Cantoblanco, E-28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid (Spain); Rubio-Bollinger, G., E-mail: gabino.rubio@uam.es [Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, Madrid E-28049 (Spain); Instituto de Ciencia de Materiales Nicolás Cabrera, Campus de Cantoblanco, E-28049 Madrid (Spain); Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, E-28049 Madrid (Spain)

    2014-08-04

    We experimentally study the surface roughness and the lateral friction force in single-layer MoS{sub 2} crystals deposited on different substrates: SiO{sub 2}, mica, and hexagonal boron nitride (h-BN). Roughness and sliding friction measurements are performed by atomic force microscopy. We find a strong dependence of the MoS{sub 2} roughness on the underlying substrate material, being h-BN the substrate which better preserves the flatness of the MoS{sub 2} crystal. The lateral friction also lowers as the roughness decreases, and attains its lowest value for MoS{sub 2} flakes on h-BN substrates. However, it is still higher than for the surface of a bulk MoS{sub 2} crystal, which we attribute to the deformation of the flake due to competing tip-to-flake and flake-to-substrate interactions.

  14. Effect of oxygen vacancy on magnetism of ZnO:Co single-crystalline nanorods

    International Nuclear Information System (INIS)

    Co-doped ZnO single-crystalline nanorods were prepared by the modified microemulsion route. The crystalline structure, morphology, oxygen vacancy emission, and hysteresis loop at low temperature and room temperature of as-prepared materials were characterized by XRD, TEM, PL spectra, and magnetic measurement respectively. The nanorods are 60–90 nm in diameter and about 2 μm in length. X-ray diffraction data, TEM images and selected area electron diffraction patterns confirm that the materials synthesized in optimal conditions are ZnO:Co single crystalline solid solution without any impurities related to Co. Magnetic measurements show that different surfactants as template in synthesis process result in ferromagnetism and paramagnetism in Zn0.95Co0.05O nanorods. The PL spectra show that the ferromagnetic samples exhibit strong oxygen vacancy emission whereas in the paramagnetic samples the oxygen vacancy emission is absent, indicating that the defects may stabilize ferromagnetic order in diluted magnetic semiconductors, resulting in high-temperature ferromagnetism. - Highlights: ► Co-doped ZnO nanorods were prepared by the modified microemulsion route. ► Different magnetic properties were observed in samples with different surfactants. ► Oxygen vacancy may stabilize ferromagnetic order in obtained materials.

  15. PbO networks composed of single crystalline nanosheets synthesized by a facile chemical precipitation method

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Synthesis of PbO networks through a simple chemical precipitation route. • The synthesis method is rapid and low-cost. • Each network is composed of single crystalline PbO nanosheets. • A possible growth mechanism is proposed for synthesized PbO networks. - Abstract: For the field of energy storage, nanostructured lead oxide (PbO) shows immense potential for increased specific energy and deep discharge for lead acid battery technologies. In this work, PbO networks composed of single crystalline nanosheets were synthesized utilizing a simple, low cost and rapid chemical precipitation method. The PbO networks were prepared in a single reaction vessel from starting reagents of lead acetate dehydrate, ammonium hydroxide and deionized water. Lead acetate dehydrate was chosen as a reagent, as opposed to lead nitrate, to eliminate the possibility of nitrate contamination of the final product. X-ray diffraction (XRD) analysis, high resolution scanning electron microscopy (HRSEM) and high resolution transmission electron microscopy (HRTEM) analysis were used to characterize the synthesized PbO networks. The reproducible method described herein synthesized pure β-PbO (massicot) powders, with no byproducts. A possible formation mechanism for these PbO networks is proposed. The growth is found to proceed predominately in the 〈1 1 1〉 and 〈2 0 0〉 directions while being limited in the 〈0 1 1〉 direction

  16. Direct growth of single-crystalline III-V semiconductors on amorphous substrates.

    Science.gov (United States)

    Chen, Kevin; Kapadia, Rehan; Harker, Audrey; Desai, Sujay; Seuk Kang, Jeong; Chuang, Steven; Tosun, Mahmut; Sutter-Fella, Carolin M; Tsang, Michael; Zeng, Yuping; Kiriya, Daisuke; Hazra, Jubin; Madhvapathy, Surabhi Rao; Hettick, Mark; Chen, Yu-Ze; Mastandrea, James; Amani, Matin; Cabrini, Stefano; Chueh, Yu-Lun; Ager Iii, Joel W; Chrzan, Daryl C; Javey, Ali

    2016-01-01

    The III-V compound semiconductors exhibit superb electronic and optoelectronic properties. Traditionally, closely lattice-matched epitaxial substrates have been required for the growth of high-quality single-crystal III-V thin films and patterned microstructures. To remove this materials constraint, here we introduce a growth mode that enables direct writing of single-crystalline III-V's on amorphous substrates, thus further expanding their utility for various applications. The process utilizes templated liquid-phase crystal growth that results in user-tunable, patterned micro and nanostructures of single-crystalline III-V's of up to tens of micrometres in lateral dimensions. InP is chosen as a model material system owing to its technological importance. The patterned InP single crystals are configured as high-performance transistors and photodetectors directly on amorphous SiO2 growth substrates, with performance matching state-of-the-art epitaxially grown devices. The work presents an important advance towards universal integration of III-V's on application-specific substrates by direct growth. PMID:26813257

  17. Versatile method for template-free synthesis of single crystalline metal and metal alloy nanowires.

    Science.gov (United States)

    Scott, John A; Totonjian, Daniel; Martin, Aiden A; Tran, Toan Trong; Fang, Jinghua; Toth, Milos; McDonagh, Andrew M; Aharonovich, Igor; Lobo, Charlene J

    2016-02-01

    Metal and metal alloy nanowires have applications ranging from spintronics to drug delivery, but high quality, high density single crystalline materials have been surprisingly difficult to fabricate. Here we report a versatile, template-free, self-assembly method for fabrication of single crystalline metal and metal alloy nanowires (Co, Ni, NiCo, CoFe, and NiFe) by reduction of metal nitride precursors formed in situ by reaction of metal salts with a nitrogen source. Thiol reduction of the metal nitrides to the metallic phase at 550-600 °C results in nanowire growth. In this process, sulfur acts as a uniaxial structure-directing agent, passivating the surface of the growing nanowires and preventing radial growth. The versatility of the method is demonstrated by achieving nanowire growth from gas-phase, solution-phase or a combination of gas- and solution-phase precursors. The fabrication method is suited to large-area CVD on a wide range of solid substrates. PMID:26763153

  18. Orientation dependent size effects in single crystalline anisotropic nanoplates with regard to surface energy

    Energy Technology Data Exchange (ETDEWEB)

    Assadi, Abbas, E-mail: assadi@aut.ac.ir; Salehi, Manouchehr, E-mail: msalehi@aut.ac.ir; Akhlaghi, Mehdi, E-mail: makhlagi@aut.ac.ir

    2015-07-17

    In this work, size dependent behavior of single crystalline normal and auxetic anisotropic nanoplates is discussed with consideration of material surface stresses via a generalized model. Bending of pressurized nanoplates and their fundamental resonant frequency are discussed for different crystallographic directions and anisotropy degrees. It is explained that the orientation effects are considerable when the nanoplates' edges are pinned but for clamped nanoplates, the anisotropy effect may be ignored. The size effects are the highest when the simply supported nanoplates are parallel to [110] direction but as the anisotropy gets higher, the size effects are reduced. The orientation effect is also discussed for possibility of self-instability occurrence in nanoplates. The results in simpler cases are compared with previous experiments for nanowires but with a correction factor. There are still some open questions for future studies. - Highlights: • Size effects in single crystalline anisotropic nanoplates are discussed. • A generalized model is established containing some physical assumptions. • Orientation dependent size effects due to material anisotropy are explained. • Bending, instability and frequencies are studied at normal/auxetic domain.

  19. Free-Standing Two-Dimensional Single-Crystalline InSb Nanosheets.

    Science.gov (United States)

    Pan, D; Fan, D X; Kang, N; Zhi, J H; Yu, X Z; Xu, H Q; Zhao, J H

    2016-02-10

    Growth of high-quality single-crystalline InSb layers remains challenging in material science. Such layered InSb materials are highly desired for searching for and manipulation of Majorana Fermions in solid state, a fundamental research task in physics today, and for development of novel high-speed nanoelectronic and infrared optoelectronic devices. Here, we report on a new route toward growth of single-crystalline, layered InSb materials. We demonstrate the successful growth of free-standing, two-dimensional InSb nanosheets on one-dimensional InAs nanowires by molecular-beam epitaxy. The grown InSb nanosheets are pure zinc-blende single crystals. The length and width of the InSb nanosheets are up to several micrometers and the thickness is down to ∼10 nm. The InSb nanosheets show a clear ambipolar behavior and a high electron mobility. Our work will open up new technology routes toward the development of InSb-based devices for applications in nanoelectronics, optoelectronics, and quantum electronics and for the study of fundamental physical phenomena. PMID:26788662

  20. Direct growth of single-crystalline III-V semiconductors on amorphous substrates

    Science.gov (United States)

    Chen, Kevin; Kapadia, Rehan; Harker, Audrey; Desai, Sujay; Seuk Kang, Jeong; Chuang, Steven; Tosun, Mahmut; Sutter-Fella, Carolin M.; Tsang, Michael; Zeng, Yuping; Kiriya, Daisuke; Hazra, Jubin; Madhvapathy, Surabhi Rao; Hettick, Mark; Chen, Yu-Ze; Mastandrea, James; Amani, Matin; Cabrini, Stefano; Chueh, Yu-Lun; Ager, Joel W., III; Chrzan, Daryl C.; Javey, Ali

    2016-01-01

    The III-V compound semiconductors exhibit superb electronic and optoelectronic properties. Traditionally, closely lattice-matched epitaxial substrates have been required for the growth of high-quality single-crystal III-V thin films and patterned microstructures. To remove this materials constraint, here we introduce a growth mode that enables direct writing of single-crystalline III-V's on amorphous substrates, thus further expanding their utility for various applications. The process utilizes templated liquid-phase crystal growth that results in user-tunable, patterned micro and nanostructures of single-crystalline III-V's of up to tens of micrometres in lateral dimensions. InP is chosen as a model material system owing to its technological importance. The patterned InP single crystals are configured as high-performance transistors and photodetectors directly on amorphous SiO2 growth substrates, with performance matching state-of-the-art epitaxially grown devices. The work presents an important advance towards universal integration of III-V's on application-specific substrates by direct growth.

  1. A simple method to synthesize single-crystalline lanthanide orthovanadate nanorods

    International Nuclear Information System (INIS)

    Single-crystalline tetragonal LnVO4 (Ln=La, Nd, Sm, Eu, Dy) nanorods were prepared via a simple hydrothermal method, in the absence of any surfactant or template using cheap and simple inorganic salts as raw materials. The products were characterized by XRD, TEM, HRTEM, and PL. It has been shown that after the hydrothermal process, LaVO4 transformed its crystal structure from monoclinic to tetragonal phase, but LnVO4 (Ln=Nd, Sm, Eu, Dy) have not exhibited the structural change. This could be associated with the change of lanthanide ion radius. TEM and HRTEM results show that the nanorods are pure, structurally uniform, single crystalline, and most of them are free from dislocations. Further study reveals the nanorods grow along the [001] direction. A possible growth mechanism of lanthanide orthovanadate nanorods was also proposed. The advantages of our method for the nanorods synthesis lie in the high yield and the low temperature and mild reaction conditions, which permit large scale production at low cost

  2. A simple method to synthesize single-crystalline lanthanide orthovanadate nanorods

    Science.gov (United States)

    Fan, Weiliu; Zhao, Wei; You, Liping; Song, Xinyu; Zhang, Weimin; Yu, Haiyun; Sun, Sixiu

    2004-12-01

    Single-crystalline tetragonal LnVO 4 ( Ln=La, Nd, Sm, Eu, Dy) nanorods were prepared via a simple hydrothermal method, in the absence of any surfactant or template using cheap and simple inorganic salts as raw materials. The products were characterized by XRD, TEM, HRTEM, and PL. It has been shown that after the hydrothermal process, LaVO 4 transformed its crystal structure from monoclinic to tetragonal phase, but LnVO 4 ( Ln=Nd, Sm, Eu, Dy) have not exhibited the structural change. This could be associated with the change of lanthanide ion radius. TEM and HRTEM results show that the nanorods are pure, structurally uniform, single crystalline, and most of them are free from dislocations. Further study reveals the nanorods grow along the [001] direction. A possible growth mechanism of lanthanide orthovanadate nanorods was also proposed. The advantages of our method for the nanorods synthesis lie in the high yield and the low temperature and mild reaction conditions, which permit large scale production at low cost.

  3. Effect of oxygen vacancy on magnetism of ZnO:Co single-crystalline nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Che, Ping, E-mail: cheping@ustb.edu.cn [Department of Chemistry and Chemical Engineering, School of Chemical and Biological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Shixiang; Sun, Changyan; Zhou, Hualei; Li, Weijun [Department of Chemistry and Chemical Engineering, School of Chemical and Biological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Tang, Jinke [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States)

    2013-02-15

    Co-doped ZnO single-crystalline nanorods were prepared by the modified microemulsion route. The crystalline structure, morphology, oxygen vacancy emission, and hysteresis loop at low temperature and room temperature of as-prepared materials were characterized by XRD, TEM, PL spectra, and magnetic measurement respectively. The nanorods are 60-90 nm in diameter and about 2 {mu}m in length. X-ray diffraction data, TEM images and selected area electron diffraction patterns confirm that the materials synthesized in optimal conditions are ZnO:Co single crystalline solid solution without any impurities related to Co. Magnetic measurements show that different surfactants as template in synthesis process result in ferromagnetism and paramagnetism in Zn{sub 0.95}Co{sub 0.05}O nanorods. The PL spectra show that the ferromagnetic samples exhibit strong oxygen vacancy emission whereas in the paramagnetic samples the oxygen vacancy emission is absent, indicating that the defects may stabilize ferromagnetic order in diluted magnetic semiconductors, resulting in high-temperature ferromagnetism. - Highlights: Black-Right-Pointing-Pointer Co-doped ZnO nanorods were prepared by the modified microemulsion route. Black-Right-Pointing-Pointer Different magnetic properties were observed in samples with different surfactants. Black-Right-Pointing-Pointer Oxygen vacancy may stabilize ferromagnetic order in obtained materials.

  4. Epitaxial growth of atomically flat gadolinia-doped ceria thin films by pulsed laser deposition

    International Nuclear Information System (INIS)

    Epitaxial growth of Ce0.8Gd0.2O2(CGO) films on (001) TiO2-terminated SrTiO3 substrates by pulsed laser deposition was investigated using in situ reflective high energy electron diffraction. The initial film growth shows a Stransky-Krastanov growth mode. However, this three-dimensional island formation is replaced by a two-dimensional island nucleation during further deposition, which results in atomically smooth CGO films. The obtained high-quality CGO films may be attractive for the electrolyte of solid-oxide fuel cells operating at low temperature. (orig.)

  5. Generation and the role of dislocations in single-crystalline phase-change In2Se3 nanowires under electrical pulses.

    Science.gov (United States)

    Mafi, Elham; Tao, Xin; Zhu, Wenguang; Gao, Yanfei; Wang, Chongmin; Gu, Yi

    2016-08-19

    We report the observation of the generation of dislocations in single-crystal phase-change In2Se3 nanowires under electrical pulses and the impact of these dislocations on electrical properties. Particularly, we correlated the atomic-scale structural characteristics with local electrical resistance variations, by performing transmission electron microscopy and scanning Kelvin probe microscopy on the same nanowires. By coupling the experimental results with first-principles density functional theory calculations, we show that the immobile dislocations are generated via vacancy condensations. Importantly, these dislocations lead to several orders of magnitude increase in the electrical resistance, while maintaining the single crystallinity of the lattice. These results significantly advance the fundamental understanding of the structure-property relation in this phase-change material under transient electrical excitations. From a practical perspective, the significant increase in the electrical resistance, driven by the formation of dislocations, can be exploited as a new electronic state in the single-crystalline phase in this phase-change material. PMID:27389929

  6. Epitaxial growth of atomically flat gadolinia-doped ceria thin films by pulsed laser deposition

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Pryds, Nini; Schou, Jørgen;

    preparation of ultrathin seed layers in the first stage of the deposition process is often envisaged to control the growth and physical properties of the subsequent coating. This work suggests that the limitations of conventional pulsed laser deposition (PLD), performed at moderate temperature (400°C), to the......10 layers with a thickness of 4 nm, 13 nm and 22 nm, respectively, grown on Mg(100), were studied by atomic force microscopy and X-ray reflectometry....... growth of dense, gas impermeable 10 mol% gadolinia-doped ceria (CGO10) solid electrolyte can be overcome by the seeding process. In order to evaluate the seed layer preparation, the effects of different thermal annealing treatments on the morphology, microstructure and surface roughness of ultrathin CGO...

  7. Improvement of electron mobility in La:BaSnO3 thin films by insertion of an atomically flat insulating (Sr,Ba)SnO3 buffer layer

    Science.gov (United States)

    Shiogai, Junichi; Nishihara, Kazuki; Sato, Kazuhisa; Tsukazaki, Atsushi

    2016-06-01

    One perovskite oxide, ASnO3 (A = Sr, Ba), is a candidate for use as a transparent conductive oxide with high electron mobility in single crystalline form. However, the electron mobility of films grown on SrTiO3 substrates does not reach the bulk value, probably because of dislocation scattering that originates from the large lattice mismatch. This study investigates the effect of insertion of bilayer BaSnO3 / (Sr,Ba)SnO3 for buffering this large lattice mismatch between La:BaSnO3 and SrTiO3 substrate. The insertion of 200-nm-thick BaSnO3 on (Sr,Ba)SnO3 bilayer buffer structures reduces the number of dislocations and improves surface smoothness of the films after annealing as proved respectively by scanning transmission electron microscopy and atomic force microscopy. A systematic investigation of BaSnO3 buffer layer thickness dependence on Hall mobility of the electron transport in La:BaSnO3 shows that the highest obtained value of mobility is 78 cm2V-1s-1 because of its fewer dislocations. High electron mobility films based on perovskite BaSnO3 can provide a good platform for transparent-conducting-oxide electronic devices and for creation of fascinating perovskite heterostructures.

  8. Large-Quantity Synthesis of Single-Crystalline Metal Indium Nano/Sub-Micron Wires

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yang; SHAN Xu-Dong; LIAO Zhi-Min; ZHAO Qing; XU Jun; YU Da-Peng

    2008-01-01

    Large quantities of metal indium single-crystalline wires with diameters ranging from tens of nanometres to a few micrometres were synthesized on Si substrates.Unlike traditional methods for the fabrication of nanowires or nanorods,liquid indium was squeezed out of the pores and cracks from porous an InAlN layer to form the wires.Continuous pushing out of liquid metal indium under strength,lowenng of liquid-solid interfaces and the confinement of the cracks all contribute to the growth of indium wires.Our experiments have shed some light on the possibility of synthesizing large quantities quasi-lD nano/sub-micron structures with specified cross-sectional geometry using the similar method.

  9. Single-crystalline Bi2S3 nanowire network film and its optical switches

    International Nuclear Information System (INIS)

    A single-crystalline bismuth sulfide (Bi2S3) nanowire network film at a centimeter scale is fabricated by the facile hydrothermal method. The Bi2S3 film is easily tape-transferred onto a soft plastic substrate, and is further used to fabricate optical switches by screen-printing an Ag electrode array on its top. Our studies demonstrate that the Bi2S3 nanowire network has a pronounced increase in conductance upon exposure to visible light, and possesses a very fast response time of about 2 ms. This work provides a simple and economic method to fabricate a high performance optical switch array and could offer great potential for a low cost, mass-manufacturing process

  10. Catalytic Growth of Graphene: Toward Large-Area Single-Crystalline Graphene.

    Science.gov (United States)

    Ago, Hiroki; Ogawa, Yui; Tsuji, Masaharu; Mizuno, Seigi; Hibino, Hiroki

    2012-08-16

    For electronic applications, synthesis of large-area, single-layer graphene with high crystallinity is required. One of the most promising and widely employed methods is chemical vapor deposition (CVD) using Cu foil/film as the catalyst. However, the CVD graphene is generally polycrystalline and contains a significant amount of domain boundaries that limit intrinsic physical properties of graphene. In this Perspective, we discuss the growth mechanism of graphene on a Cu catalyst and review recent development in the observation and control of the domain structure of graphene. We emphasize the importance of the growth condition and crystallinity of the Cu catalyst for the realization of large-area, single-crystalline graphene. PMID:26295775

  11. Fabrication and Characterization of Single-Crystalline AgSbTe2 Nanowire Arrays

    International Nuclear Information System (INIS)

    Ternary semiconducting AgSbTe2 nanowire arrays were synthesized for the first time by using the direct-current electrodeposition technique. X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, and transmission electron microscopy analyses indicate that the nanowire arrays are high filling, ordered, single crystalline and the nanowires have a highly preferential orientation grown along the [100] direction. Annealing studies show that compared with other temperatures, annealing at 100°C can significantly increase the crystallinity of AgSbTe2 nanowires. The optical absorbance spectra of the AgSbTe2 nanowire arrays show that the optical band gap has a strong blue shift with decreasing the diameter of the nanowire

  12. Laser ablation of single-crystalline silicon by radiation of pulsed frequency-selective fiber laser

    Science.gov (United States)

    Veiko, V. P.; Skvortsov, A. M.; Huynh, C. T.; Petrov, A. A.

    2015-07-01

    We have studied the process of destruction of the surface of a single-crystalline silicon wafer scanned by the beam of a pulsed ytterbium-doped fiber laser radiation with a wavelength of λ = 1062 nm. It is established that the laser ablation can proceed without melting of silicon and the formation of a plasma plume. Under certain parameters of the process (radiation power, beam scan velocity, and beam overlap density), pronounced oxidation of silicon microparticles with the formation of a characteristic loose layer of fine powdered silicon dioxide has been observed for the first time. The range of lasing and beam scanning regimes in which the growth of SiO2 layer takes place is determined.

  13. The recombination channels of luminescence excitation in YAG:Yb single crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Zakharko, Ya.M. [Faculty of Electronics, Ivan Franko National University of Lviv, 107 Tarnavskogo str., Lviv 79017 (Ukraine)], E-mail: zakharko@electronics.wups.lviv.ua; Luchechko, A.P. [Faculty of Electronics, Ivan Franko National University of Lviv, 107 Tarnavskogo str., Lviv 79017 (Ukraine); Ubizskii, S.B. [Lviv Polytechnic National University, 12, Bandera srt., Lviv 79013 (Ukraine); Syvorotka, I.I. [Scientific Research Company ' Carat' , 202, Stryjska str., Lviv 79031 (Ukraine); Martynyuk, N.V. [Lviv Polytechnic National University, 12, Bandera srt., Lviv 79013 (Ukraine); Syvorotka, I.M. [Scientific Research Company ' Carat' , 202, Stryjska str., Lviv 79031 (Ukraine)

    2007-04-15

    Absorption and emission spectra, luminescence decay kinetics and thermostimulated luminescence of X-ray irradiated YAG:Yb single crystalline films were studied. Two emission bands peaked at 420 and 488 nm have been detected in the investigated films. The strong thermal quenching of luminescence band at 488 nm was observed above 160 K. The influence of growth conditions and annealing in air on the lifetime of Yb{sup 3+} ion excited state in the IR spectral region have been revealed. The recombination mechanisms of the f-f transition at Yb{sup 3+} ion excitation, as well as the mechanism of lifetime shortening for the excited Yb{sup 3+} luminescence have been discussed.

  14. Measuring the mobility of single crystalline wires and its dependence on temperature and carrier density

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Cleber A; Berengue, Olivia M; Kamimura, Hanay; Chiquito, Adenilson J [NanO LaB-Departamento de Fisica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil); Leite, Edson R, E-mail: amorim@df.ufscar.br [Laboratorio Interdisciplinar de EletroquImica e Ceramicas, Departamento de Quimica, Universidade Federal de Sao Carlos, CEP 13565-905, CP 676, Sao Carlos, Sao Paulo (Brazil)

    2011-05-25

    Kinetic transport parameters are fundamental for the development of electronic nanodevices. We present new results for the temperature dependence of mobility and carrier density in single crystalline In{sub 2}O{sub 3} samples and the method of extraction of these parameters which can be extended to similar systems. The data were obtained using a conventional Hall geometry and were quantitatively described by the semiconductor transport theory characterizing the electron transport as being controlled by the variable range hopping mechanism. A comprehensive analysis is provided showing the contribution of ionized impurities (low temperatures) and acoustic phonon (high temperatures) scattering mechanisms to the electron mobility. The approach presented here avoids common errors in kinetic parameter extraction from field effect data, serving as a versatile platform for direct investigation of any nanoscale electronic materials.

  15. Magnetotransport measurements of single crystalline heavy fermion YbNi2B2C

    International Nuclear Information System (INIS)

    We have measured transverse (B perpendicular to I) and longitudinal (B parallel I) magnetoresistance on a single crystalline sample of YbNi2B2C. A remarkably large anisotropic transverse magnetoresistance was found when applying magnetic field parallel or perpendicular to the c-axis of the tetragonal crystallographic structure. A pronounced maximum at 10 T develops below 4 K in the transverse magnetoresistance when the magnetic field is applied along the c-axis, whereas a minimum is found at 7 T below 4 K when the applied field is perpendicular to the c-axis. Above 5 K both configurations (B parallel c and B perpendicular to c) show a negative magnetoresistance. Finally, the possibility of a metamagnetic-like transition in this compound will be discussed in conjunction with high field magnetization experiments. (orig.)

  16. Small-angle neutron scattering from anisotropic single-crystalline materials

    International Nuclear Information System (INIS)

    'Isotropic' small-angle scattering (SAS), i.e. without azimuthal dependence around the primary beam, occurs only for specific configurations of the scattering objects if single-crystalline material is studied. For decomposing Ni-based alloy single crystals, SAS signals are generally highly anisotropic. From analysis of two-dimensional SAS patterns, important information on the evolution of the morphology and on the three-dimensional spatial arrangement of the precipitates from the early stages of decomposition can be extracted. The real-space information obtained from transmission electron microscopy is an excellent complement to the reciprocal-space information extracted from SAS data. The complementary use of these two techniques offers a valuable approach to the study of precipitation phenomena. (orig.)

  17. Exploring metamagnetism of single crystalline EuNiGe3 by neutron scattering

    Science.gov (United States)

    Fabrèges, X.; Gukasov, A.; Bonville, P.; Maurya, A.; Thamizhavel, A.; Dhar, S. K.

    2016-06-01

    We present here a neutron diffraction study, both in zero field and as a function of magnetic field, of the magnetic structure of the tetragonal intermetallic EuNiGe3 on a single crystalline sample. This material is known to undergo a cascade of transitions, first at 13.2 K towards an incommensurate modulated magnetic structure, then at 10.5 K to an antiferromagnetic structure. We show here that the low-temperature phase presents a spiral moment arrangement with wave vector k =(1/4 ,δ ,0 ) . For a magnetic field applied along the tetragonal c axis, the square root of the scattering intensity of the (1 0 1) reflection matches very well the complex metamagnetic behavior of the magnetization along c measured previously. For the magnetic field applied along the b axis, two magnetic transitions are observed below the transition to a fully polarized state.

  18. Formation of carbon nanostructures containing single-crystalline cobalt carbides by ion irradiation method

    Science.gov (United States)

    Wang, Zhipeng; Yusop, Zamri; Ghosh, Pradip; Hayashi, Yasuhiko; Tanemura, Masaki

    2011-02-01

    Carbon nanofibers (CNFs) with a diameter of 17 nm, and carbon nanoneedles (CNNs) with sharp tips have been synthesized on graphite substrates by ion irradiation of argon ions with the Co supplies rate of 1 and 3.4 nm/min, respectively. Energy dispersive X-ray spectrometry, combined with selected area electron diffraction patterns has been used to identify the chemical composition and crystallinity of these carbon nanostructures. The CNFs were found to be amorphous in nature, while the structures of the CNNs consisted of cubic CoCx, orthorhombic Co2C and Co3C depending on the cobalt content in the CNNs. The diameter of the carbide crystals was almost as large as the diameter of the CNN. Compared to the ion-induced nickel carbides and iron carbides, the formation of single-crystalline cobalt carbides might be due to the high temperature produced by the irradiation.

  19. Formation of carbon nanostructures containing single-crystalline cobalt carbides by ion irradiation method

    International Nuclear Information System (INIS)

    Carbon nanofibers (CNFs) with a diameter of 17 nm, and carbon nanoneedles (CNNs) with sharp tips have been synthesized on graphite substrates by ion irradiation of argon ions with the Co supplies rate of 1 and 3.4 nm/min, respectively. Energy dispersive X-ray spectrometry, combined with selected area electron diffraction patterns has been used to identify the chemical composition and crystallinity of these carbon nanostructures. The CNFs were found to be amorphous in nature, while the structures of the CNNs consisted of cubic CoCx, orthorhombic Co2C and Co3C depending on the cobalt content in the CNNs. The diameter of the carbide crystals was almost as large as the diameter of the CNN. Compared to the ion-induced nickel carbides and iron carbides, the formation of single-crystalline cobalt carbides might be due to the high temperature produced by the irradiation.

  20. Synthesis of single crystalline CdS nanowires with polyethylene glycol 400 as inducing template

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Solvothermal technique, an one-step soft solution-processing route was successfully employed to synthesize single crystalline CdS nanowires in ethylenediamine medium at lower temperature (170 □) for 1-8 d. In this route, polyethylene glycol 400 (PEG400)was used as surfactant, which played a crucial role in preferentially oriented growth of semiconductor nanowires. Characterizations of as-prepared CdS nanowires by X-ray powder diffraction(XRD), transmission electron microscopy(TEM) indicate that the naonowires,with typical diameters of 20nm and lengths up to several micrometers, have preferential [001] orientation. Also, investigations into the physical properties of the CdS nanowires were conducted with UV-Vis absorption spectroscopy and photoluminescence emission spectroscopy. The excitonic photo-optical phenomena of the nanowires shows the potential in the practical applications.

  1. Exciton creation in LuAlO3 single crystalline film

    International Nuclear Information System (INIS)

    Single crystalline films (SCF) of LuAP attract attention because of the perspective of its application as 2D screens for X-ray registration with high spatial resolution. An intensive sharp reflectivity peak at the edge of the fundamental absorption region with maximum at 8.37 eV at 10 K was found for a series of LuAP SCF grown by liquid phase epitaxy on YAP substrate. The dependence of the peak maximum and profile on temperature demonstrates its exciton origin. The absorption spectrum was calculated from reflectivity using Kramers-Kronig relations; the bandgap value was determined for LuAP as Eg=8.44 eV at 10 K. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Carrier Transport Mechanism in Single Crystalline Organic Semiconductor Thin Film Elucidated by Visualized Carrier Motion.

    Science.gov (United States)

    Matsubara, Kohei; Abe, Kentaro; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-04-01

    Time-resolved microscopic second harmonic generation (TRM-SHG) measurement was conducted to evaluate temperature dependence of the anisotropic carrier transport process in 6,13-Bis(triisopropylsilylethynyl) (TIPS) pentacene single crystalline domains for two orthogonal directions. Enhancement of the electric field induced SHG (EFI-SHG) signal at the electrode edge at low temperature suggests the presence of potential drop in the injection process. We directly evaluated temperature dependence of the carrier mobility by taking into account the potential drop, and concluded that the Marcus theory is appropriate to interpret the carrier transport in anisotropic TIPS pentacene thin film. TRM-SHG method is a facile and effective way to directly visualize transport process in anisotropic materials and to evaluate injection and transport processes simultaneously. PMID:27451638

  3. Macroscopic Quantum Tunneling in a Bi2Sr2CaCu2O8+δ Single Crystalline Whisker

    Science.gov (United States)

    Kubo, Yuimaru; Takahide, Yamaguchi; Ueda, Shinya; Takano, Yoshihiko; Ootuka, Youiti

    2010-06-01

    Macroscopic quantum tunneling (MQT) has been observed in an intrinsic Josephson junction (IJJ) stack of a Bi2Sr2CaCu2O8+δ (BSCCO) single crystalline whisker with high precision using a home made setup. The cross-over temperature between thermal activation and MQT was about 260 mK, and the Josephson plasma frequency was estimated to be 86 GHz. Both the thermal escape theory and the MQT theory are consistent with the experiments. These facts strongly suggest that single crystalline BSCCO whiskers are high enough quality to be used as intrinsic Josephson quantum devices such as intrinsic Josephson phase qubits. This is the first demonstration of MQT in BSCCO single crystalline whiskers.

  4. Mass production of graphene-like single-crystalline NbSe2 (004) nanosheets via intercalant-assisted thermal cleavage

    International Nuclear Information System (INIS)

    The author reports the mass production of dense inorganic graphene-like exfoliated single-crystalline niobium diselenide (NbSe2) (004) multilayered nanosheets standing on quartz substrate. Similar to the most-used micromechanical cleavage to exfoliated NbSe2 nanosheets, the synthesis was performed starting directly from bulk powdered counterparts, but using a novel type of substrate-irrelevant vapor-phase exfoliation. A possible intercalant-assisted thermal cleavage growth mechanism for the NbSe2-derived nanosheets, including a combination of intercalant injection-atomic delamination-thermal exfoliation-lateral growth, is discussed. This two-component nanosheet-forming technique appears to potentially work on homologous series of sandwich-type inorganic layered 2H transition-metal dichalcogenide compounds under proper experimental conditions as well. (orig.)

  5. One-step synthesis of single-crystalline CdSe nanorods via γ-ray irradiation

    International Nuclear Information System (INIS)

    High aspect ratio single-crystalline CdSe micrometer rods with a uniform and smooth surface texture are synthesized via γ-ray irradiation at 170degC. The length of the rods and the diameter of the CdSe micrometer rods are about tens micron and 240-300 nm, respectively. (author)

  6. Fast growth of inch-sized single-crystalline graphene from a controlled single nucleus on Cu-Ni alloys

    Science.gov (United States)

    Wu, Tianru; Zhang, Xuefu; Yuan, Qinghong; Xue, Jiachen; Lu, Guangyuan; Liu, Zhihong; Wang, Huishan; Wang, Haomin; Ding, Feng; Yu, Qingkai; Xie, Xiaoming; Jiang, Mianheng

    2016-01-01

    Wafer-scale single-crystalline graphene monolayers are highly sought after as an ideal platform for electronic and other applications. At present, state-of-the-art growth methods based on chemical vapour deposition allow the synthesis of one-centimetre-sized single-crystalline graphene domains in ~12 h, by suppressing nucleation events on the growth substrate. Here we demonstrate an efficient strategy for achieving large-area single-crystalline graphene by letting a single nucleus evolve into a monolayer at a fast rate. By locally feeding carbon precursors to a desired position of a substrate composed of an optimized Cu-Ni alloy, we synthesized an ~1.5-inch-large graphene monolayer in 2.5 h. Localized feeding induces the formation of a single nucleus on the entire substrate, and the optimized alloy activates an isothermal segregation mechanism that greatly expedites the growth rate. This approach may also prove effective for the synthesis of wafer-scale single-crystalline monolayers of other two-dimensional materials.

  7. High-Operation-Temperature Plasmonic Nanolasers on Single-Crystalline Aluminum.

    Science.gov (United States)

    Chou, Yu-Hsun; Wu, Yen-Mo; Hong, Kuo-Bin; Chou, Bo-Tsun; Shih, Jheng-Hong; Chung, Yi-Cheng; Chen, Peng-Yu; Lin, Tzy-Rong; Lin, Chien-Chung; Lin, Sheng-Di; Lu, Tien-Chang

    2016-05-11

    The recent development of plasmonics has overcome the optical diffraction limit and fostered the development of several important components including nanolasers, low-operation-power modulators, and high-speed detectors. In particular, the advent of surface-plasmon-polariton (SPP) nanolasers has enabled the development of coherent emitters approaching the nanoscale. SPP nanolasers widely adopted metal-insulator-semiconductor structures because the presence of an insulator can prevent large metal loss. However, the insulator is not necessary if permittivity combination of laser structures is properly designed. Here, we experimentally demonstrate a SPP nanolaser with a ZnO nanowire on the as-grown single-crystalline aluminum. The average lasing threshold of this simple structure is 20 MW/cm(2), which is four-times lower than that of structures with additional insulator layers. Furthermore, single-mode laser operation can be sustained at temperatures up to 353 K. Our study represents a major step toward the practical realization of SPP nanolasers. PMID:27089144

  8. Magnetic and Transport properties of single crystalline FeSi1-xGex

    Science.gov (United States)

    Yeo, Sunmog; Nakatsuji, Satoru; Bianchi, Andrea; Drymiotis, Fivos; Fisk, Zachary

    2002-03-01

    Title : Magnetic and Transport properties of single crystalline FeSi1-xGex Author : S. Yeo, S. Nakatsuji, A. D. Bianchi*, F. R. Drymiotis, Z. Fisk National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32306 The isomorphic iron intermetallic compounds FeSi and FeGe have significantly distinct ground states: Kondo insulator and ferromagnetic metal, respectively. We have recently succeeded in growing single crystals of the whole range of the solution system FeSi1-xGex and performed the susceptibility, resistivity and specific heat measurements throughout the composition range. In the Kondo insulating phase near FeSi, we find that the temperature dependence of the susceptibility is well described by a thermally activated Curie law. Starting from 622 K in the case of FeSi, the activation gap systematically decreases below 190 K for Ge concentration near xc ? 0.25. Above xc, we find the sudden appearance of a ferromagnetic phase with Curie temperature of 125 K, comparable to the gap of the neighboring Kondo insulating phase. Both resistivity and specific measurements suggest that the insulator to metal transition occurs around xc. We will show the phase diagram constructed on the basis of these results, and discuss the origin of the interesting evolution of the ground state. This works were supported by NSF-DMR-9971348 * Present address : Los Alamos National Laboratory, Los Alamos, New Mexico 87545

  9. SXPS studies of single crystalline CdTe/CdS interfaces

    International Nuclear Information System (INIS)

    Highlights: •Investigation of single crystalline surfaces of CdS and CdTe by SXPS. •Investigation of growth of CdS and CdTe on crystalline surfaces by SXPS and LEED. •Determination of band alignment between CdS and CdTe. -- Abstract: The interface formation between CdS and CdTe is investigated by synchrotron induced photoemission measurements at the BESSY II storage ring. CdS and CdTe layers were deposited by thermal evaporation on CdTe and CdS single crystal substrates with two different orientations for each substrate. Surface core level shifts show a passivation of dangling bonds for CdS substrates overgrown by CdTe. Te-Te bonds are found even on a 200 nm thick layer of CdS on CdTe. A valence band offset of 1.02 ± 0.05 eV, corresponding to a conduction band offset of −0.09 ± 0.05 eV is determined, independent of the substrate type and orientation and in agreement with measurements of polycrystalline interfaces. This alignment of every bands with a very small barrier for electron transfer and a maximized barrier for hole transport to the electron accepting front contact promises ideal properties for devices like CdS/CdTe hetero junction thin film solar cells

  10. Heterojunction Diodes and Solar Cells Fabricated by Sputtering of GaAs on Single Crystalline Si

    Directory of Open Access Journals (Sweden)

    Santiago Silvestre

    2015-04-01

    Full Text Available This work reports fabrication details of heterojunction diodes and solar cells obtained by sputter deposition of amorphous GaAs on p-doped single crystalline Si. The effects of two additional process steps were investigated: A hydrofluoric acid (HF etching treatment of the Si substrate prior to the GaAs sputter deposition and a subsequent annealing treatment of the complete layered system. A transmission electron microscopy (TEM exploration of the interface reveals the formation of a few nanometer thick SiO2 interface layer and some crystallinity degree of the GaAs layer close to the interface. It was shown that an additional HF etching treatment of the Si substrate improves the short circuit current and degrades the open circuit voltage of the solar cells. Furthermore, an additional thermal annealing step was performed on some selected samples before and after the deposition of an indium tin oxide (ITO film on top of the a-GaAs layer. It was found that the occurrence of surface related defects is reduced in case of a heat treatment performed after the deposition of the ITO layer, which also results in a reduction of the dark saturation current density and resistive losses.

  11. Fabrication and optical properties of single-crystalline beta barium borate nanorods

    International Nuclear Information System (INIS)

    Single-crystalline beta barium borate (β-BaB2O4, β-BBO) nanorods with a diameter of 10-20 nm and a length up to several micrometers have been fabricated by a cetyltrimethyl ammonium bromide assisted hydrothermal method and subsequent annealing in air at 700 oC. Structure and composition characterizations were performed by X-ray powder diffraction, Fourier transform infrared spectra, Raman spectra and X-ray photoelectron spectra. The results indicate that β-BBO nanorods have an orthorhombic structure with space group of C3v-R3C. Linear and nonlinear optical properties of β-BBO nanorods were examined by the absorption spectra, photoluminescence spectra and the powders second-harmonic generation measurement. The optical characterizations indicate that β-BBO nanorods are transparent from ultraviolet to the mid-infrared regions and exhibit a strong ultraviolet emission band at 382 nm. Compared with that of urea, higher second-harmonic generation conversion efficiency of β-BBO nanorods was measured. The possible growth process of β-BBO nanorods was also discussed briefly.

  12. Surface Engineering of Copper Foils for Growing Centimeter-Sized Single-Crystalline Graphene.

    Science.gov (United States)

    Lin, Li; Li, Jiayu; Ren, Huaying; Koh, Ai Leen; Kang, Ning; Peng, Hailin; Xu, H Q; Liu, Zhongfan

    2016-02-23

    The controlled growth of high-quality graphene on a large scale is of central importance for applications in electronics and optoelectronics. To minimize the adverse impacts of grain boundaries in large-area polycrystalline graphene, the synthesis of large single crystals of monolayer graphene is one of the key challenges for graphene production. Here, we develop a facile surface-engineering method to grow large single-crystalline monolayer graphene by the passivation of the active sites and the control of graphene nucleation on copper surface using the melamine pretreatment. Centimeter-sized hexagonal single-crystal graphene domains were successfully grown, which exhibit ultrahigh carrier mobilities exceeding 25,000 cm(2) V(-1) s(-1) and quantum Hall effects on SiO2 substrates. The underlying mechanism of melamine pretreatments were systematically investigated through elemental analyses of copper surface in the growth process of large single-crystals. This present work provides a surface design of a catalytic substrate for the controlled growth of large-area graphene single crystals. PMID:26832229

  13. Fabrication of 3D fractal structures using nanoscale anisotropic etching of single crystalline silicon

    International Nuclear Information System (INIS)

    When it comes to high-performance filtration, separation, sunlight collection, surface charge storage or catalysis, the effective surface area is what counts. Highly regular fractal structures seem to be the perfect candidates, but manufacturing can be quite cumbersome. Here it is shown-–for the first time—that complex 3D fractals can be engineered using a recursive operation in conventional micromachining of single crystalline silicon. The procedure uses the built-in capability of the crystal lattice to form self-similar octahedral structures with minimal interference of the constructor. The silicon fractal can be used directly or as a mold to transfer the shape into another material. Moreover, they can be dense, porous, or like a wireframe. We demonstrate, after four levels of processing, that the initial number of octahedral structures is increased by a factor of 625. Meanwhile the size decreases 16 times down to 300 nm. At any level, pores of less than 100 nm can be fabricated at the octahedral vertices of the fractal. The presented technique supports the design of fractals with Hausdorff dimension D free of choice and up to D = 2.322. (paper)

  14. Ultrasonic synthesis, formation mechanism and optical properties of single-crystalline Pb(OH)Br microrings

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guizhen, E-mail: wangguizhen0@hotmail.com [Key Laboratory of Ministry of Education for Application Technology of Chemical Materials in Hainan Superior Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China); Key Laboratory of Chinese Education Ministry for Tropical Biological Resources, Hainan University, Haikou 570228 (China); Wan Gengping [Key Laboratory of Ministry of Education for Application Technology of Chemical Materials in Hainan Superior Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China); Key Laboratory of Chinese Education Ministry for Tropical Biological Resources, Hainan University, Haikou 570228 (China); Lin Shiwei; Yu Wenhui [Key Laboratory of Ministry of Education for Application Technology of Chemical Materials in Hainan Superior Resources, College of Materials and Chemical Engineering, Hainan University, Haikou 570228 (China)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Elliptic Pb(OH)Br microrings were synthesized by a simple sonochemical process. Black-Right-Pointing-Pointer Size distribution of the median holes could be controlled. Black-Right-Pointing-Pointer Microrings were formed by ultrasonic etching accompanying the Ostwald ripening. Black-Right-Pointing-Pointer Pb(OH)Br microrings exhibit optical properties of semiconductors. - Abstract: Novel elliptic Pb(OH)Br microrings have been controllably synthesized on a large scale by a simple sonochemical process in aqueous solution. The structure characterizations of such microrings were investigated in detail by means of X-ray powder diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the uniform orthorhombic phase of Pb(OH)Br microrings with good crystallinity can be obtained and such ring-like Pb(OH)Br is single crystalline with the (0 1 1) plane as the 2D exposed surface. The influence of reaction time and alkali sources on the evolution of structures has been studied. The possible hollowing growth mechanism for the Pb(OH)Br microrings has been discussed. Meanwhile, the ultraviolet-visible absorbance spectra and photoluminescence microrings show their ultraviolet absorption and green emitting behavior, indicating that the elliptic Pb(OH)Br microrings have great potential to be applied in luminescent and optoelectronic devices.

  15. Ultrasonic synthesis, formation mechanism and optical properties of single-crystalline Pb(OH)Br microrings

    International Nuclear Information System (INIS)

    Highlights: ► Elliptic Pb(OH)Br microrings were synthesized by a simple sonochemical process. ► Size distribution of the median holes could be controlled. ► Microrings were formed by ultrasonic etching accompanying the Ostwald ripening. ► Pb(OH)Br microrings exhibit optical properties of semiconductors. - Abstract: Novel elliptic Pb(OH)Br microrings have been controllably synthesized on a large scale by a simple sonochemical process in aqueous solution. The structure characterizations of such microrings were investigated in detail by means of X-ray powder diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the uniform orthorhombic phase of Pb(OH)Br microrings with good crystallinity can be obtained and such ring-like Pb(OH)Br is single crystalline with the (0 1 1) plane as the 2D exposed surface. The influence of reaction time and alkali sources on the evolution of structures has been studied. The possible hollowing growth mechanism for the Pb(OH)Br microrings has been discussed. Meanwhile, the ultraviolet–visible absorbance spectra and photoluminescence microrings show their ultraviolet absorption and green emitting behavior, indicating that the elliptic Pb(OH)Br microrings have great potential to be applied in luminescent and optoelectronic devices.

  16. Exfoliation of Threading Dislocation-Free, Single-Crystalline, Ultrathin Gallium Nitride Nanomembranes

    KAUST Repository

    ElAfandy, Rami T.

    2014-04-01

    Despite the recent progress in gallium nitride (GaN) growth technology, the excessively high threading dislocation (TD) density within the GaN crystal, caused by the reliance on heterogeneous substrates, impedes the development of high-efficiency, low-cost, GaN-based heterostructure devices. For the first time, the chemical exfoliation of completely TD-free, single-crystalline, ultrathin (tens of nanometers) GaN nanomembranes is demonstrated using UV-assisted electroless chemical etching. These nanomembranes can act as seeding layers for subsequent overgrowth of high-quality GaN. A model is proposed, based on scanning and transmission electron microscopy as well as optical measurements to explain the physical processes behind the formation of the GaN nanomembranes. These novel nanomembranes, once transferred to other substrates, present a unique and technologically attractive path towards integrating high-efficiency GaN optical components along with silicon electronics. Interestingly, due to their nanoscale thickness and macroscopic sizes, these nanomembranes may enable the production of flexible GaN-based optoelectronics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Single-crystalline ZnO sheet Source-Gated Transistors

    Science.gov (United States)

    Dahiya, A. S.; Opoku, C.; Sporea, R. A.; Sarvankumar, B.; Poulin-Vittrant, G.; Cayrel, F.; Camara, N.; Alquier, D.

    2016-01-01

    Due to their fabrication simplicity, fully compatible with low-cost large-area device assembly strategies, source-gated transistors (SGTs) have received significant research attention in the area of high-performance electronics over large area low-cost substrates. While usually based on either amorphous or polycrystalline silicon (α-Si and poly-Si, respectively) thin-film technologies, the present work demonstrate the assembly of SGTs based on single-crystalline ZnO sheet (ZS) with asymmetric ohmic drain and Schottky source contacts. Electrical transport studies of the fabricated devices show excellent field-effect transport behaviour with abrupt drain current saturation (IDSSAT) at low drain voltages well below 2 V, even at very large gate voltages. The performance of a ZS based SGT is compared with a similar device with ohmic source contacts. The ZS SGT is found to exhibit much higher intrinsic gain, comparable on/off ratio and low off currents in the sub-picoamp range. This approach of device assembly may form the technological basis for highly efficient low-power analog and digital electronics using ZnO and/or other semiconducting nanomaterial.

  18. Nb-doped single crystalline MoS2 field effect transistor

    International Nuclear Information System (INIS)

    We report on the demonstration of a p-type, single crystalline, few layer MoS2 field effect transistor (FET) using Niobium (Nb) as the dopant. The doping concentration was extracted and determined to be ∼3 × 1019/cm3. We also report on bilayer Nb-doped MoS2 FETs with ambipolar conduction. We found that the current ON-OFF ratio of the Nb-doped MoS2 FETs changes significantly as a function of the flake thickness. We attribute this experimental observation to bulk-type electrostatic effect in ultra-thin MoS2 crystals. We provide detailed analytical modeling in support of our claims. Finally, we show that in the presence of heavy doping, even ultra-thin 2D-semiconductors cannot be fully depleted and may behave as a 3D material when used in transistor geometry. Our findings provide important insights into the doping constraints of 2D materials, in general

  19. Reversible Sodium Ion Insertion in Single Crystalline Manganese Oxide Nanowires with Long Cycle Life

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Yuliang; Xiao, Lifen; Wang, Wei; Choi, Daiwon; Nie, Zimin; Yu, Jianguo; Saraf, Laxmikant V.; Yang, Zhenguo; Liu, Jun

    2011-07-26

    Single crystalline Na4Mn9O18 nanowires were synthesized via pyrolysis of polyacrylate salt precursors prepared by in-situ polymerization of the metal salts and acrylate acid, followed by calcinations at an appropriate temperature to achieve good crystalline structure and uniform nanowire morphology with an average diameter of 50 nm. The Na4Mn9O18 nanowires have shown a high, reversible, and near theoretical sodium ion insertion capacity (128 mA h g-1 at 0.1C), excellent long cyclability (77% capacity retention for 1000 cycles at 0.5 C), along with good rate capability. Good capacity and charge-discharge stability are also observed for full cell experiments using a pyrolyzed carbon as the anode, therefore demonstrating the potential of these materials for sodium-ion batteries for large scale energy storage. Furthermore, this research shows that a good crystallinity and small particles are required to enhance the Na-ion diffusion and increase the stability of the electrode materials for long charge-discharge cycles.

  20. Synthesis and structure of large single crystalline silver hexagonal microplates suitable for micromachining

    International Nuclear Information System (INIS)

    We report a simple one-step synthesis method of large single crystalline Ag (111) hexagonal microplates with sharp edges and a size of up to tens of microns. Single silver crystals were produced by reduction silver nitrate aqueous solution with 4-(methylamino)phenol sulfate. Scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, selected area electron diffraction and optical microscopy techniques were combined to characterize the crystals. It is shown that the microplates can be easily dispersed and transferred as single objects onto different substrates and subsequently used as a high quality plasmonic starting material for micromachining of future nanocomponents, using modern top-down techniques like focused-ion beam milling and gas injection deposition. - Highlights: • Synthesis of large Ag hexagonal microplates with high crystallinity. • It is shown and discussed the role of twinning for the anisotropic 2D growth. • The Ag plates are stable in water and can be dispersed onto different substrates. • Their positioning and subsequent micromachining with FIB/GIS is demonstrated. • Suitable starting material for future plasmonic nanocomponents

  1. Synthesis and structure of large single crystalline silver hexagonal microplates suitable for micromachining

    Energy Technology Data Exchange (ETDEWEB)

    Lyutov, Dimitar L.; Genkov, Kaloyan V.; Zyapkov, Anton D.; Tsutsumanova, Gichka G.; Tzonev, Atanas N. [Department of Solid State Physics and Microelectronics, Faculty of Physics, University of Sofia, 5, J. Bouchier Blvd, Sofia (Bulgaria); Lyutov, Lyudmil G. [Department of General and Inorganic Chemistry, Faculty of Chemistry, University of Sofia, 1, J. Bouchier Blvd, Sofia (Bulgaria); Russev, Stoyan C., E-mail: scr@phys.uni-sofia.bg [Department of Solid State Physics and Microelectronics, Faculty of Physics, University of Sofia, 5, J. Bouchier Blvd, Sofia (Bulgaria)

    2014-01-15

    We report a simple one-step synthesis method of large single crystalline Ag (111) hexagonal microplates with sharp edges and a size of up to tens of microns. Single silver crystals were produced by reduction silver nitrate aqueous solution with 4-(methylamino)phenol sulfate. Scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, selected area electron diffraction and optical microscopy techniques were combined to characterize the crystals. It is shown that the microplates can be easily dispersed and transferred as single objects onto different substrates and subsequently used as a high quality plasmonic starting material for micromachining of future nanocomponents, using modern top-down techniques like focused-ion beam milling and gas injection deposition. - Highlights: • Synthesis of large Ag hexagonal microplates with high crystallinity. • It is shown and discussed the role of twinning for the anisotropic 2D growth. • The Ag plates are stable in water and can be dispersed onto different substrates. • Their positioning and subsequent micromachining with FIB/GIS is demonstrated. • Suitable starting material for future plasmonic nanocomponents.

  2. Recovery Act : Near-Single-Crystalline Photovoltaic Thin Films on Polycrystalline, Flexible Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Venkat Selvamanickam; Alex Freundlich

    2010-11-29

    III-V photovoltaics have exhibited efficiencies above 40%, but have found only a limited use because of the high cost of single crystal substrates. At the other end of the spectrum, polycrystalline and amorphous thin film solar cells offer the advantage of low-cost fabrication, but have not yielded high efficiencies. Our program is based on single-crystalline-like thin film photovoltaics on polycrystalline substrates using biaxially-textured templates made by Ion Beam-Assisted Deposition (IBAD). MgO templates made by IBAD on flexible metal substrate have been successfully used for epitaxial growth of germanium films. In spite of a 4.5% lattice mismatch, heteroepitaxial growth of Ge was achieved on CeO2 that was grown on IBAD MgO template. Room temperature optical bandgap of the Ge films was identified at 0.67 eV indicating minimal residual strain. Refraction index and extinction coefficient values of the Ge films were found to match well with that measured from a reference Ge single crystal. GaAs has been successfully grown epitaxially on Ge on metal substrate by molecular beam epitaxy. RHEED patterns indicate self annihilation of antiphase boundaries and the growth of a single domain GaAs. The GaAs is found to exhibit strong photoluminescence signal and, an existence of a relatively narrow (FWHM~20 meV) band-edge excitons measured in this film indicates a good optoelectronic quality of deposited GaAs. While excellent epitaxial growth has been achieved in GaAs on flexible metal substrates, the defect density of the films as measured by High Resolution X-ray Diffraction and etch pit experiments showed a high value of 5 * 10^8 per cm^2. Cross sectional transmission electron microscopy of the multilayer architecture showed concentration of threading dislocations near the germanium-ceria interface. The defect density was found decrease as the Ge films were made thicker. The defects appear to originate from the MgO layer presumably because of large lattice mismatches

  3. Vertical Single-Crystalline Organic Nanowires on Graphene: Solution-Phase Epitaxy and Optical Microcavities.

    Science.gov (United States)

    Zheng, Jian-Yao; Xu, Hongjun; Wang, Jing Jing; Winters, Sinéad; Motta, Carlo; Karademir, Ertuğrul; Zhu, Weigang; Varrla, Eswaraiah; Duesberg, Georg S; Sanvito, Stefano; Hu, Wenping; Donegan, John F

    2016-08-10

    Vertically aligned nanowires (NWs) of single crystal semiconductors have attracted a great deal of interest in the past few years. They have strong potential to be used in device structures with high density and with intriguing optoelectronic properties. However, fabricating such nanowire structures using organic semiconducting materials remains technically challenging. Here we report a simple procedure for the synthesis of crystalline 9,10-bis(phenylethynyl) anthracene (BPEA) NWs on a graphene surface utilizing a solution-phase van der Waals (vdW) epitaxial strategy. The wires are found to grow preferentially in a vertical direction on the surface of graphene. Structural characterization and first-principles ab initio simulations were performed to investigate the epitaxial growth and the molecular orientation of the BPEA molecules on graphene was studied, revealing the role of interactions at the graphene-BPEA interface in determining the molecular orientation. These free-standing NWs showed not only efficient optical waveguiding with low loss along the NW but also confinement of light between the two end facets of the NW forming a microcavity Fabry-Pérot resonator. From an analysis of the optical dispersion within such NW microcavities, we observed strong slowing of the waveguided light with a group velocity reduced to one-tenth the speed of light. Applications of the vertical single-crystalline organic NWs grown on graphene will benefit from a combination of the unique electronic properties and flexibility of graphene and the tunable optical and electronic properties of organic NWs. Therefore, these vertical organic NW arrays on graphene offer the potential for realizing future on-chip light sources. PMID:27438189

  4. High-quality single crystalline NiO with twin phases grown on sapphire substrate by metalorganic vapor phase epitaxy

    Directory of Open Access Journals (Sweden)

    Kazuo Uchida

    2012-12-01

    Full Text Available High-quality single crystalline twin phase NiO grown on sapphire substrates by metalorganic vapor phase epitaxy is reported. X-ray rocking curve analysis of NiO films grown at different temperatures indicates a minimum full width at half maximum of the cubic (111 diffraction peak of 0.107° for NiO film grown at as low as 550 °C. Detailed microstructural analysis by Φ scan X-ray diffraction and transmission electron microscopy reveal that the NiO film consists of large single crystalline domains with two different crystallographic orientations which are rotated relative to each other along the [111] axis by 60°. These single crystal domains are divided by the twin phase boundaries.

  5. Single-crystalline nanowires of SiC synthesized by carbothermal reduction of electrospun PVP/TEOS composite fibres

    International Nuclear Information System (INIS)

    Nanowires of SiC were synthesized by carbothermally reducing PVP/TEOS composite fibres obtained by electrospinning. High-resolution transmission electron microscopy (HRTEM) and selected-area electron diffraction (SAED) indicated that the SiC nanowires are single crystalline in nature. Both Fourier-transformed infrared spectroscopy and HRTEM indicated that a thin layer of SiO2 was formed on the outer surface of the nanowire as a result of post-heat treatment for the removal of residual carbon. Such SiO2 layer protects the inner SiC fibre from further oxidation. The formation mechanism of single-crystalline SiC nanowires was proposed based on our understanding and characterizations. The growth of the nanowire is believed to be along the (111) of its cubic cell

  6. Enhanced non-volatile resistive switching in suspended single-crystalline ZnO nanowire with controllable multiple states

    Science.gov (United States)

    Zhang, Rui; Pang, Wei; Zhang, Qing; Chen, Yan; Chen, Xuejiao; Feng, Zhihong; Yang, Jianhua; Zhang, Daihua

    2016-08-01

    Resistive switching nanostructures are a promising candidate for next-generation non-volatile memories. In this report, we investigate the switching behaviors of single-crystalline ZnO nanowires suspended in air. They exhibit significantly higher current density, lower switching voltage, and more pronounced multiple conductance states compared to nanowires in direct contact with substrate. We attribute the effect to enhanced Joule heating efficiency, reduced surface scattering, and more significantly, the positive feedback established between the current density and local temperature in the suspended nanowires. The proposed mechanism has been quantitatively examined by finite element simulations. We have also demonstrated an innovative approach to initiating the current–temperature mutual enhancement through illumination by ultraviolet light, which further confirmed our hypothesis and enabled even greater enhancement. Our work provides further insight into the resistive switching mechanism of single-crystalline one-dimensional nanostructures, and suggests an effective means of performance enhancement and device optimization.

  7. Fluorescence signals of core-shell quantum dots enhanced by single crystalline gold caps on silicon nanowires

    International Nuclear Information System (INIS)

    We use nanoscale (20-300 nm in diameter) single crystalline gold (Au)-caps on silicon nanowires (NWs) grown by the vapor-liquid-solid (VLS) growth mechanism to enhance the fluorescence photoluminescence (PL) signals of highly dilute core/shell CdSeTe/ZnS quantum dots (QDs) in aqueous solution (10-5 M). For NWs without Au-caps, as they appear, for example, after Au etching in aqua regia or buffered KI/I2-solution, essentially no fluorescence signal of the same diluted QDs could be observed. Fluorescence PL signals were measured using excitation with a laser wavelength of 633 nm. The signal enhancement by single crystalline, nanoscale Au-caps is discussed and interpreted based on finite element modeling (FEM).

  8. Aligned Single-Crystalline Perovskite Microwire Arrays for High-Performance Flexible Image Sensors with Long-Term Stability.

    Science.gov (United States)

    Deng, Wei; Zhang, Xiujuan; Huang, Liming; Xu, Xiuzhen; Wang, Liang; Wang, Jincheng; Shang, Qixun; Lee, Shuit-Tong; Jie, Jiansheng

    2016-03-16

    A simple, low-cost blade-coating method is developed for the large-area fabrication of single-crystalline aligned CH3NH3PbI3 microwire (MW) arrays. The solution-coating method is applicable to flexible substrates, enabling the fabrication of MW-array-based photodetectors with excellent long-term stability, flexibility, and bending durability. Integrated devices from such photodetectors demonstrate high performance for high-resolution, flexible image sensors. PMID:26780594

  9. Dynamic response of single crystalline copper subjected to quasi-isentropic laser and gas-gun driven loading

    Science.gov (United States)

    Meyers, M.; Jarmakani, H.; McNaney, J. M.; Schneider, M.; Nguyen, J. H.; Kad, B.

    2006-08-01

    Single crystalline copper was subjected to quasi-isentropic compression via gas-gun and laser loading at pressures between 18 GPa and 59 GPa. The deformation substructure was analyzed via transmission electron microscopy (TEM). Twins and laths were evident at the highest pressures, and stacking faults and dislocation cells in the intermediate and lowest pressures, respectively. The Preston-Tonks-Wallace (PTW) constitutive description was used to model the slip-twinning process in both cases.

  10. Magnetocrystalline anisotropy and exchange interaction of single crystalline RCo4M (R=Y,Gd,Ho; M=Al,B)

    International Nuclear Information System (INIS)

    The RCo4M compounds (R: rare earth; M: Al, B) can be obtained from RCo5 by substituting M for Co. For the first time, large single crystalline samples of RCo4M (R: Y, Gd, Ho) have been grown. Some differences have been found between the effects of Al and B substitution. In particular, a first-order magnetisation process associated with the Co sublattice is reported for RCo4B (R: Gd, Y). (orig.)

  11. A simple one-pot synthesis of single-crystalline magnetite hollow spheres from a single iron precursor

    International Nuclear Information System (INIS)

    This paper presents a facile route using a simple solvothermal reaction to synthesize monodisperse and single-crystalline Fe3O4 hollow spheres. Fe3O4 hollow spheres with a mean diameter of 200 nm are fabricated using the coordination compound [Fe(urea)6]Cl3 as the sole iron source, in the absence of any other additives. TEM, SEM and HRTEM results show that single-crystalline Fe3O4 hollow spheres are composed of well-aligned nanoparticles. The as-prepared hollow spheres have a Brunauer-Emmett-Teller (BET) surface area of about 16.251 m2 g-1 with an average pore size of 3.537 nm. The hollow spheres display obvious ferromagnetism at room temperature with a saturation magnetization of 79.58 emu g-1, a remanent magnetization of 19.1 emu g-1 and coercivity of 133.5 Oe. The growth mechanism of single-crystalline Fe3O4 hollow spheres is attributed to the cooperation of oriented aggregation and Ostwald ripening.

  12. Nonhydrolytic colloidal synthesis of ligand-capped single-crystalline NdOCl nanocubes and their magnetic properties

    International Nuclear Information System (INIS)

    Highlights: • Single-crystalline NdOCl nanocubes were fabricated by nonhydrolytic colloidal route. • The NdOCl nanocubes have a pure tetragonal PbFCl matlockite phase. • The NdOCl nanocubes show ferromagnetism at room temperature. - Abstract: In the present study, monodisperse NdOCl nanocubes with single-crystalline structure were fabricated through a novel nonhydrolytic colloidal route, in which NdCl3⋅6H2O was only used as the neodymium source and oleylamine was the coordinating ligand as well as the surfactant. TEM image indicates that the nanostructures show cubic shape with an edge length of about 27 nm. XRD pattern and SAED analysis of numerous nanocubes indicate that the NdOCl nanocubes have a pure tetragonal PbFCl matlockite phase. HRTEM image and FFT pattern of individual NdOCl nanocubes reveal that each cube is single crystalline. Magnetization analysis suggests that the NdOCl nanocubes show ferromagnetic characteristic at room temperature. These results are significant for the investigations of rare earth-based nanocrystals. Besides, this novel nonhydrolytic colloidal route is believed to be a potential general strategy for the synthesis of monodispersed rare earth oxychlorides nanocrystals

  13. A facile one-step method for synthesising a parallelogram-shaped single-crystalline ZnO nanosheet

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • A simple method to synthesise ZnO nanosheets is described. • Parallelogram-shaped ZnO nanosheets were obtained with single-crystalline structure. • A specific mechanism of the growth was suggested. - Abstract: ZnO nanosheets are found to be useful in many fields such as sensors and electronics. Non-uniform-shaped ZnO nanosheets are synthesised using several methods; moreover, uniformly shaped ones are less studied. Here, we report on a simple one-step method to synthesise parallelogram-shaped single-crystalline ZnO nanosheets. By controlling the reaction of Zn(NO3)2 and hexamethylenetetramine (HMT) in ethanol, average 30 nm-thick nanosheets with a high aspect ratio of 1:100 were obtained. The parallelogram angles were between 97° and 99°. Transmission electron microscopy (TEM) diffraction and X-ray diffraction (XRD) showed that the nanosheets were wurtzite-structured single-crystalline ZnO. Moreover, a growth mechanism of these parallelogram nanosheets is suggested based on the experimental results. These results suggest a new simple solution process to synthesise uniformly shaped ZnO nanosheets allowing large-scale production to be employed

  14. Single-crystalline spherical β-Ga2O3 particles: Synthesis, N-doping and photoluminescence properties

    International Nuclear Information System (INIS)

    We report on the synthesis of single-crystalline spherical β-Ga2O3 particles by a simple method in ambient atmosphere. No pre-treatment, catalyst, substrate, or gas flow was required during the synthesis process. The well-dispersed Ga2O3 particles display uniform spherical morphology with an average diameter of ∼200 nm. Photoluminescence studies indicate that the Ga2O3 particles exhibit a broad blue-green light emission and an interesting red light emission at room temperature. The red light emission can be further tuned by post-annealing of the particles in ammonia atmosphere. The present single-crystalline β-Ga2O3 particles with spherical morphology, uniform sub-micrometer sizes and tunable light emission are envisaged to be of high promise for applications in white-LED phosphors and optoelectronic devices. -- Highlights: ► We prepared single-crystalline spherical β-Ga2O3 particles in ambient atmosphere. ► The particles display uniform spherical morphology with an average diameter of ∼200 nm. ► The Ga2O3 particles exhibit a broad blue-green light and an interesting red light emission. ► The red light emission can be further tuned by post-annealing of the particles

  15. A model system for carbohydrates interactions on single-crystalline Ru surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thanh Nam

    2015-07-01

    In this thesis, I present a model system for carbohydrate interactions with single-crystalline Ru surfaces. Geometric and electronic properties of copper phthalocyanine (CuPc) on top of graphene on hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10) surfaces have been studied. First, the Fermi surfaces and band structures of the three Ru surfaces were investigated by high-resolution angle-resolved photoemission spectroscopy. The experimental data and theoretical calculations allow to derive detailed information about the momentum-resolved electronic structure. The results can be used as a reference to understand the chemical and catalytic properties of Ru surfaces. Second, graphene layers were prepared on the three different Ru surfaces. Using low-energy electron diffraction and scanning tunneling microscopy, it was found that graphene can be grown in well-ordered structures on all three surfaces, hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10), although they have different surface symmetries. Evidence for a strong interaction between graphene and Ru surfaces is a 1.3-1.7 eV increase in the graphene π-bands binding energy with respect to free-standing graphene sheets. This energy variation is due to the hybridization between the graphene pi bands and the Ru 4d electrons, while the lattice mismatch does not play an important role in the bonding between graphene and Ru surfaces. Finally, the geometric and electronic structures of CuPc on Ru(10 anti 10), graphene/Ru(10 anti 10), and graphene/Ru(0001) have been studied in detail. CuPc molecules can be grown well-ordered on Ru(10 anti 10) but not on Ru(0001). The growth of CuPc on graphene/Ru(10 anti 10) and Ru(0001) is dominated by the Moire pattern of graphene. CuPc molecules form well-ordered structures with rectangular unit cells on graphene/Ru(10 anti 10) and Ru(0001). The distance of adjacent CuPc molecules is 15±0.5 Aa and 13±0.5 Aa on graphene/Ru(0001

  16. High-perfomance Ce-doped multicomponent garnet single crystalline film scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu.; Gorbenko, V.; Zorenko, T. [Institute of Physics, Kazimierz Wielki, University in Bydgoszcz, Powstancow, Wielkopolskich str., 2, 85090, Bydgoszcz (Poland); Department of Electronics of Ivan Franko, National University of Lviv, Gen. Tarnavskiy str. 17, 79017, Lviv (Ukraine); Sidletskiy, O. [Institute for Single Crystals, National Academy of Sciences of Ukraine, Lenina str., 60, 61001, Kharkiv (Ukraine); Fedorov, A. [SSI Institute for Single Crystals, National Academy of Sciences of Ukraine, Lenina str., 60, 61178, Kharkiv (Ukraine); Bilski, P.; Twardak, A. [Institute of Nuclear Physic, Polish Academy of Sciences, Radzikowskiego str., 176, 31-342, Krakow (Poland)

    2015-08-15

    We report for the first time the optimized content and excellent scintillation properties of single crystalline film (SCF) scintillators of multicomponent Gd{sub 3-x}Lu{sub x} Al{sub 5-y}Ga{sub y} O{sub 12}:Ce garnet compounds grown by liquid phase epitaxy (LPE) method. The Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce and Gd{sub 3}Al{sub 2.75-2}Ga{sub 2.25-3}O{sub 12}:Ce SCF show the light yield (LY) comparable with that of high-quality bulk crystal analogues of these garnets but faster scintillation decay and very low thermoluminescence in the above room temperature range. To our knowledge, these SCF possess the highest LY values ever obtained in LPE grown garnet SCF scintillators exceeding by at least 1.5-1.6 times the values previously reported for SCF scintillators. Left figure: image of Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (PbO) (inset, left) and Gd{sub 3}Al{sub 2.35}Ga{sub 2.65}O{sub 12}:Ce (BaO) (inset, right) SCF scintillators, grown by LPE method onto Gd{sub 3}Al{sub 2.5}Ga{sub 2.5}O{sub 12} (GAGG) substrate; in the middle, green-yellow light emitting by Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (BaO) SCF under 350 nm laser illumination. Right figure: XRD pattern of (1200) planes of the Gd{sub 1.5}Lu{sub 1.5}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (PbO) (black) and Gd{sub 3}Al{sub 2.75}Ga{sub 2.25}O{sub 12}:Ce (BaO) (red) SCFs, grown onto GAGG substrates. The film/substrate lattice misfit is -0.73% and -0.3%, respectively. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Growth, structure and magnetic properties of single crystalline Fe/CoO/Ag(001) bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Abrudan, R.M.

    2007-07-16

    The structural and magnetic properties of epitaxially deposited single-crystalline CoO layers and Fe/CoO bilayers on Ag(001) were investigated. CoO films on Ag(001) exhibit (1 x 1) Low Energy Electron Diffraction (LEED) patterns similar to the clean Ag(001) substrate. The vertical interlayer spacing of the CoO films, deduced from a kinematic analysis of LEED I(E) curves, is a {sub perpendicular} {sub to} /2=2.17 Aa, slightly expanded along the film normal. Scanning Tunneling Microscopy (STM) show a big improvement in the surface roughness after annealing the CoO films at 750 K in oxygen atmosphere. Magnetic measurements using the magneto-optical Kerr effect (MOKE) show a characteristic increase of the coercive field when the Fe/CoO bilayer system is cooled down from room temperature to 150 K. The ordering temperature for the antiferromagnetic layer is in the same range as the Neel temperature for bulk CoO (T{sub N}=290 K). X-ray absorption spectroscopy was employed to probe magnetic and electronic properties with elemental selectivity. Absorption spectra taken from bilayers with different amounts of deposited Fe show only a weak indication for the formation of Fe oxide at the Fe/CoO interface (0.3 ML Fe). From the spectral shape it is concluded that an FeO type of oxide is formed. X-ray Magnetic Circular Dichroism (XMCD) measurements exhibit a sizeable induced ferromagnetic signal at the Co L{sub 2,3} absorption edge, corresponding to an interface layer of 1.1 ML in which the magnetic spins couple with the Fe layer. The angular dependence of the X-ray Magnetic Linear Dichroism (XMLD) and X-ray Magnetic Circular Dichroism XMCD at both the Co and Fe L{sub 2,3} edges shows the orientation of the Co and Fe moments in the bilayers with respect to the crystallographic direction. PhotoElectron Emission Microscope (PEEM) is used to image each ferromagnetic and antiferromagnetic layer separately. Magnetic contrast due to the induced magnetic spins at the interface is also

  18. Nanoscale magneto-structural coupling in as-deposited and freestanding single-crystalline Fe7Pd3 ferromagnetic shape memory alloy thin films

    Directory of Open Access Journals (Sweden)

    Anja Landgraf, Alexander M Jakob, Yanhong Ma and Stefan G Mayr

    2013-01-01

    Full Text Available Ferromagnetic shape memory alloys are characterized by strong magneto-mechanical coupling occurring at the atomic scale causing large magnetically inducible strains at the macroscopic level. Employing combined atomic and magnetic force microscopy studies at variable temperature, we systematically explore the relation between the magnetic domain pattern and the underlying structure for as-deposited and freestanding single-crystalline Fe7Pd3 thin films across the martensite–austenite transition. We find experimental evidence that magnetic domain appearance is strongly affected by the presence and absence of nanotwinning. While the martensite–austenite transition upon temperature variation of as-deposited films is clearly reflected in topography by the presence and absence of a characteristic surface corrugation pattern, the magnetic domain pattern is hardly affected. These findings are discussed considering the impact of significant thermal stresses arising in the austenite phase. Freestanding martensitic films reveal a hierarchical structure of micro- and nanotwinning. The associated domain organization appears more complex, since the dominance of magnetic energy contributors alters within this length scale regime.

  19. Structure, morphology, and magnetic properties of Fe nanoparticles deposited onto single-crystalline surfaces

    Directory of Open Access Journals (Sweden)

    Armin Kleibert

    2011-01-01

    Full Text Available Background: Magnetic nanostructures and nanoparticles often show novel magnetic phenomena not known from the respective bulk materials. In the past, several methods to prepare such structures have been developed – ranging from wet chemistry-based to physical-based methods such as self-organization or cluster growth. The preparation method has a significant influence on the resulting properties of the generated nanostructures. Taking chemical approaches, this influence may arise from the chemical environment, reaction kinetics and the preparation route. Taking physical approaches, the thermodynamics and the kinetics of the growth mode or – when depositing preformed clusters/nanoparticles on a surface – the landing kinetics and subsequent relaxation processes have a strong impact and thus need to be considered when attempting to control magnetic and structural properties of supported clusters or nanoparticles.Results: In this contribution we focus on mass-filtered Fe nanoparticles in a size range from 4 nm to 10 nm that are generated in a cluster source and subsequently deposited onto two single crystalline substrates: fcc Ni(111/W(110 and bcc W(110. We use a combined approach of X-ray magnetic circular dichroism (XMCD, reflection high energy electron diffraction (RHEED and scanning tunneling microscopy (STM to shed light on the complex and size-dependent relation between magnetic properties, crystallographic structure, orientation and morphology. In particular XMCD reveals that Fe particles on Ni(111/W(110 have a significantly lower (higher magnetic spin (orbital moment compared to bulk iron. The reduced spin moments are attributed to the random particle orientation being confirmed by RHEED together with a competition of magnetic exchange energy at the interface and magnetic anisotropy energy in the particles. The RHEED data also show that the Fe particles on W(110 – despite of the large lattice mismatch between iron and tungsten – are

  20. Conducting LaAlO3/SrTiO3 heterointerfaces on atomically-flat substrates prepared by deionized-water.

    Science.gov (United States)

    Connell, J G; Nichols, J; Gruenewald, J H; Kim, D-W; Seo, S S A

    2016-01-01

    We have investigated how the recently-developed water-leaching method for atomically-flat SrTiO3 (STO) substrates affects the transport properties of LaAlO3 (LAO) and STO heterointerfaces. Using pulsed laser deposition at identical growth conditions, we have synthesized epitaxial LAO thin-films on two different STO substrates, which are prepared by water-leaching and buffered hydrofluoric acid (BHF) etching methods. The structural, transport, and optical properties of LAO/STO heterostructures grown on water-leached substrates show the same high-quality as the samples grown on BHF-etched substrates. These results indicate that the water-leaching method can be used to grow complex oxide heterostructures with atomically well-defined heterointerfaces without safety concerns. PMID:27033248

  1. Metallic ground state and glassy transport in single crystalline URh$_2$Ge$_2$: Enhancement of disorder effects in a strongly correlated electron system

    OpenAIRE

    Süllow, S.; Maksimov, I.; Otop, A.; Litterst, F. J.; Perucchi, A.; Degiorgi, L.; Mydosh, J. A.

    2004-01-01

    We present a detailed study of the electronic transport properties on a single crystalline specimen of the moderately disordered heavy fermion system URh$_2$Ge$_2$. For this material, we find glassy electronic transport in a single crystalline compound. We derive the temperature dependence of the electrical conductivity and establish metallicity by means of optical conductivity and Hall effect measurements. The overall behavior of the electronic transport properties closely resembles that of ...

  2. Single crystalline Er2O3:sapphire films as potentially high-gain amplifiers at telecommunication wavelength

    International Nuclear Information System (INIS)

    Single crystalline thin films of Er2O3, demonstrating efficient 1.5 μm luminescence of Er3+ at room temperature were grown on Al2O3 substrate by molecular beam epitaxy. The absorption coefficient at 1.536 μm was found to reach 270 cm−1 translating in a maximal possible gain of 1390 dBcm−1. In conjunction with the 10% higher refractive index as compared to Al2O3, this opens the possibility to use Er2O3:sapphire films as short-length waveguide amplifiers in telecommunication

  3. Mechanical energy losses in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Zelada, Griselda I. [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Lambri, Osvaldo Agustin [Laboratorio de Materiales, Escuela de Ingenieria Electrica, Facultad de Ciencias Exactas, Ingenieria y Agrimensura, Universidad Nacional de Rosario, Avda. Pellegrini 250, 2000 Rosario (Argentina); Instituto de Fisica Rosario - CONICET, Member of the CONICET& #x27; s Research Staff, Avda. Pellegrini 250, 2000 Rosario (Argentina); Bozzano, Patricia B. [Laboratorio de Microscopia Electronica, Unidad de Actividad Materiales, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499, 1650 San Martin (Argentina); Garcia, Jose Angel [Departamento de Fisica Aplicada II, Facultad de Ciencias y Tecnologia, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao, Pais Vasco (Spain)

    2012-10-15

    Mechanical spectroscopy (MS) and transmission electron microscopy (TEM) studies have been performed in plastically deformed and electron plus neutron irradiated high purity single crystalline molybdenum, oriented for single slip, in order to study the dislocation dynamics in the temperature range within one third of the melting temperature. A damping peak related to the interaction of dislocation lines with both prismatic loops and tangles of dislocations was found. The peak temperature ranges between 900 and 1050 K, for an oscillating frequency of about 1 Hz. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Current-direction dependence of the transport properties in single-crystalline face-centered-cubic cobalt films

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, X.; Liang, J. H.; Chen, B. L.; Li, J. X.; Ding, Z.; Wu, Y. Z., E-mail: wuyizheng@fudan.edu.cn [Department of Physics, State Key Laboratory of Surface Physics and Collaborative Innovation Center of Advanced Microstructures, Fudan University, Shanghai 200433 (China); Ma, D. H. [Department of Energy Engineering, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-07-28

    Face-centered-cubic cobalt films are epitaxially grown on insulating LaAlO{sub 3}(001) substrates by molecular beam epitaxy. Transport measurements are conducted in different current directions relative to the crystal axes. We find that the temperature dependent anisotropic magnetoresistance ratio strongly depends on the current direction. However, the anomalous Hall effect shows isotropic behavior independent of the current direction. Our results demonstrate the interplay between the current direction and the crystalline lattice in single-crystalline ferromagnetic films. A phenomenological analysis is presented to interpret the experimental data.

  5. Investigation of electrically-active deep levels in single-crystalline diamond by particle-induced charge transient spectroscopy

    Science.gov (United States)

    Kada, W.; Kambayashi, Y.; Ando, Y.; Onoda, S.; Umezawa, H.; Mokuno, Y.; Shikata, S.; Makino, T.; Koka, M.; Hanaizumi, O.; Kamiya, T.; Ohshima, T.

    2016-04-01

    To investigate electrically-active deep levels in high-resistivity single-crystalline diamond, particle-induced charge transient spectroscopy (QTS) techniques were performed using 5.5 MeV alpha particles and 9 MeV carbon focused microprobes. For unintentionally-doped (UID) chemical vapor deposition (CVD) diamond, deep levels with activation energies of 0.35 eV and 0.43 eV were detected which correspond to the activation energy of boron acceptors in diamond. The results suggested that alpha particle and heavy ion induced QTS techniques are the promising candidate for in-situ investigation of deep levels in high-resistivity semiconductors.

  6. Self-Assembled Organic Single Crystalline Nanosheet for Solution Processed High-Performance n-Channel Field-Effect Transistors.

    Science.gov (United States)

    Kim, Jin Hong; Park, Sang Kyu; Kim, Jong H; Whang, Dong Ryeol; Yoon, Won Sik; Park, Soo Young

    2016-07-01

    Submillimeter sized n-channel organic single crystalline nanosheet based on dicyanodistyrylbenzene derivative, (2E,2'E)-3,3'-(2,5-dimethoxy-1,4-pheny-lene)bis(2-(5-(4-(trifluoromethyl)phenyl)thiophen-2-yl)acrylonitrile) (Me-4-TFPTA), is developed. Strong π-π interaction, hydrogen bonding interactions derived from cyano group (CN) as well as solvent inclusion along the lateral direction play a key role in forming nanosheet morphology. Me-4-TFPTA nanosheets exhibit excellent field-effect electron mobility of up to 7.81 cm(2) v(-1) s(-1) . PMID:27165653

  7. High quality single atomic layer deposition of hexagonal boron nitride on single crystalline Rh(111) four-inch wafers.

    Science.gov (United States)

    Hemmi, A; Bernard, C; Cun, H; Roth, S; Klöckner, M; Kälin, T; Weinl, M; Gsell, S; Schreck, M; Osterwalder, J; Greber, T

    2014-03-01

    The setup of an apparatus for chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) and its characterization on four-inch wafers in ultra high vacuum (UHV) environment is reported. It provides well-controlled preparation conditions, such as oxygen and argon plasma assisted cleaning and high temperature annealing. In situ characterization of a wafer is accomplished with target current spectroscopy. A piezo motor driven x-y stage allows measurements with a step size of 1 nm on the complete wafer. To benchmark the system performance, we investigated the growth of single layer h-BN on epitaxial Rh(111) thin films. A thorough analysis of the wafer was performed after cutting in atmosphere by low energy electron diffraction, scanning tunneling microscopy, and ultraviolet and X-ray photoelectron spectroscopies. The apparatus is located in a clean room environment and delivers high quality single layers of h-BN and thus grants access to large area UHV processed surfaces, which had been hitherto restricted to expensive, small area single crystal substrates. The facility is versatile enough for customization to other UHV-CVD processes, e.g., graphene on four-inch wafers. PMID:24689614

  8. Production and characterization of nanocomposite thin films based on Ni matrix reinforced with SnO{sub 2} single-crystalline nanowires for electrical contact applications

    Energy Technology Data Exchange (ETDEWEB)

    Miguel, F.L., E-mail: f.miguel@mx.uni-saarland.de [Saarland University, Functional Materials, 66123 Saarbrücken (Germany); Müller, R. [University of Cologne, Inorganic and Materials Chemistry, 50939 Cologne (Germany); Weinmann, M.; Hempelmann, R. [Saarland University, Physical Chemistry, 66123 Saarbrücken (Germany); Mathur, S. [University of Cologne, Inorganic and Materials Chemistry, 50939 Cologne (Germany); Mücklich, F. [Saarland University, Functional Materials, 66123 Saarbrücken (Germany)

    2014-08-01

    Highlights: • Metal-matrix nanocomposites obtained, reinforced by nanowires attached to substrate. • Nanocrystalline matrix in spite of direct-current electrodeposition being used. • Strong influence of SnO{sub 2} nanowires on surface and microstructural properties. • Previous coating of nanowires (with Ag) improved the matrix deposition. - Abstract: Nanocomposite thin films based on electrodeposited Ni matrix reinforced with SnO{sub 2} single-crystalline nanowires grown onto Si substrates by chemical vapor deposition were produced. The composites were characterized by means of scanning and transmission electron microscopy (for imaging, selected area diffraction and transmission Kikuchi diffraction), atomic force microscopy (for 3D surface profiling and roughness evaluation) and 4-point probe electrical resistivity measurements. The Ni matrices obtained were nanocrystalline in nature (41 nm crystallite mean size) even though low direct current electrodeposition was used. The topography and roughness of the samples were strongly affected by the presence of the nanowires as so was the electrical resistivity, which could be improved by Ag-coating the nanowires. A comparison with pure Ni produced in the same way is presented for determining the effects of the SnO{sub 2} nanowires.

  9. Experimental investigation of off-stoichiometry and 3d transition metal (Mn, Ni, Cu-substitution in single-crystalline FePt thin films

    Directory of Open Access Journals (Sweden)

    Takuya Ono

    2016-05-01

    Full Text Available 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 ( K u comp of FePt-Mn and FePt-Cu followed a similar trend to that predicted by the rigid-band model, although the K u comp of the FePt-Mn thin films dropped more rapidly than the rigid band calculation. However, it followed the recent first-principles calculation.

  10. Effect of electron irradiation on nanogroove-networked single-crystalline and dendritic polycrystalline platinum nanosheets prepared from lyotropic surfactant liquid-crystal templates

    International Nuclear Information System (INIS)

    Using transmission electron microscopy (TEM) electron irradiation effects were studied for nanogroove-network structured single-crystalline and dendritic polycrystalline Pt nanosheets 50-60 nm in size. These two nanosheets with nearly the same average groove-width or dendritic spacing of 1.3-1.4 nm were prepared from the mixed and single surfactant liquid crystalline templates, respectively. On exposure to electron beam for 20 min at the acceleration voltage of 200 kV, the nanogrooved nanosheets were morphologically little affected, but the dendritic ones were transformed into less branched polycrystalline structures with spacings distributed around ∼1.7 nm. The shape transformation of the latter occurred by the combined mechanism of segmental migration and atomic diffusion. These observations indicate that the nanogrooved Pt nanosheets are highly stabilized by the grooved but crystallographically continuous Pt framework, leading to their extremely high thermo-resistance, in marked contrast to the polycrystalline dendritic structures constructed of crystallographically discontinuous linkages of nanoblocks

  11. Oriented single crystalline TiO2 nano-pillar arrays directly grown on titanium substrate in tetramethylammonium hydroxide solution

    International Nuclear Information System (INIS)

    Oriented single crystalline titanium dioxide (TiO2) nano-pillar arrays were directly synthesized on the Ti plate in tetramethylammonium hydroxide (TMAOH) solution by one-pot hydrothermal method. The samples were characterized respectively by means of field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). Results showed that the TiO2 nano-pillar with a tetrahydral bipyramidal tip grew vertically on the titanium substrate. HRTEM and Raman results confirmed that the TiO2 nano-pillar arrays were single crystalline anatase. The controls of morphology, size, and orientation of the nano-pillar could be achieved by varying the solution concentration and hydrothermal temperature. Furthermore, the special morphology of the TiO2 nano-pillar arrays was caused by the selectively absorption of the tetramethylammonium (TMA) through hydrogen bonds on the lattice planes parallel to (0 0 1) of anatase TiO2. Less grain boundaries and direct electrical pathway for electron transferring were crucial for the superior photoelectrochemical properties of the single anatase TiO2 nano-pillar arrays. This approach provides a facile in situ method to synthesize TiO2 nano-pillar arrays with a special morphology on titanium substrate.

  12. Anisotropic surface strain in single crystalline cobalt nanowires and its impact on the diameter-dependent Young's modulus

    KAUST Repository

    Huang, Xiaohu

    2013-01-01

    Understanding and measuring the size-dependent surface strain of nanowires are essential to their applications in various emerging devices. Here, we report on the diameter-dependent surface strain and Young\\'s modulus of single-crystalline Co nanowires investigated by in situ X-ray diffraction measurements. Diameter-dependent initial longitudinal elongation of the nanowires is observed and ascribed to the anisotropic surface stress due to the Poisson effect, which serves as the basis for mechanical measurements. As the nanowire diameter decreases, a transition from the "smaller is softer" regime to the "smaller is tougher" regime is observed in the Young\\'s modulus of the nanowires, which is attributed to the competition between the elongation softening and the surface stiffening effects. Our work demonstrates a new nondestructive method capable of measuring the initial surface strain and estimating the Young\\'s modulus of single crystalline nanowires, and provides new insights on the size effect. © 2013 The Royal Society of Chemistry.

  13. Hydrothermal transformation of titanate nanotubes into single-crystalline TiO2 nanomaterials with controlled phase composition and morphology

    International Nuclear Information System (INIS)

    Single-crystalline TiO2 nanomaterials were synthesized by hydrothermally treating suspensions of H-titanate nanotubes and characterized by XRD, TEM, and HRTEM. The effects of the pH values of the suspensions and the hydrothermal temperatures on the phase composition and morphology of the obtained TiO2 nanomaterials were systematically investigated. The H-titanate nanotubes were predominately transformed into anatase nanoparticle with rhombic shape when the pH value was greater than or equal to 1.0, whereas primarily turned into rutile nanorod with two pyramidal ends at the pH value less than or equal to 0.5. We propose a possible mechanism for hydrothermal transformation of H-titanate nanotubes into single-crystalline TiO2 nanomaterials. While the H-titanate nanotubes transform into tiny anatase nanocrystallites of ca. 3 nm in size, the formed nanocrystallites as an intermediate grow into the TiO2 nanomaterials with controlled phase composition and morphology. This growth process involves the steps of protonation, oriented attachment, and Ostwald ripening.

  14. Single Crystalline Co3O4 Nanocrystals Exposed with Different Crystal Planes for Li-O2 Batteries

    Science.gov (United States)

    Su, Dawei; Dou, Shixue; Wang, Guoxiu

    2014-08-01

    Single crystalline Co3O4 nanocrystals exposed with different crystal planes were synthesised, including cubic Co3O4 nanocrystals enclosed by {100} crystal planes, pseudo octahedral Co3O4 enclosed by {100} and {110} crystal planes, Co3O4 nanosheets exposed by {110} crystal planes, hexagonal Co3O4 nanoplatelets exposed with {111} crystal planes, and Co3O4 nanolaminar exposed with {112} crystal planes. Well single crystalline features of these Co3O4 nanocrystals were confirmed by FESEM and HRTEM analyses. The electrochemical performance for Li-O2 batteries shows that Co3O4 nanocrystals can significantly reduce the discharge-charge over-potential via the effect on the oxygen evolution reaction (OER). From the comparison on their catalytic performances, we found that the essential factor to promote the oxygen evolution reactions is the surface crystal planes of Co3O4 nanocrystals, namely, crystal planes-dependent process. The correlation between different Co3O4 crystal planes and their effect on reducing charge-discharge over-potential was established: {100} < {110} < {112} < {111}.

  15. Magnetic properties of single crystalline expanded austenite obtained by plasma nitriding of austenitic stainless steel single crystals.

    Science.gov (United States)

    Menéndez, Enric; Templier, Claude; Garcia-Ramirez, Pablo; Santiso, José; Vantomme, André; Temst, Kristiaan; Nogués, Josep

    2013-10-23

    Ferromagnetic single crystalline [100], [110], and [111]-oriented expanded austenite is obtained by plasma nitriding of paramagnetic 316L austenitic stainless steel single crystals at either 300 or 400 °C. After nitriding at 400 °C, the [100] direction appears to constitute the magnetic easy axis due to the interplay between a large lattice expansion and the expected decomposition of the expanded austenite, which results in Fe- and Ni-enriched areas. However, a complex combination of uniaxial (i.e., twofold) and biaxial (i.e., fourfold) in-plane magnetic anisotropies is encountered. It is suggested that the former is related to residual stress-induced effects while the latter is associated to the in-plane projections of the cubic lattice symmetry. Increasing the processing temperature strengthens the biaxial in-plane anisotropy in detriment of the uniaxial contribution, in agreement with a more homogeneous structure of expanded austenite with lower residual stresses. In contrast to polycrystalline expanded austenite, single crystalline expanded austenite exhibits its magnetic easy axes along basic directions. PMID:24028676

  16. Position-controlled vertical arrays of single-crystalline ZnO nanowires on periodically polarity inverted templates

    International Nuclear Information System (INIS)

    Highlights: ► We demonstrated a vertically aligned ZnO nanorods on isolated 1D patterns based on periodically polarity-inverted ZnO template. ► Successful position control of single crystalline ZnO nanostructures without using of any catalyst. ► Suggestion of new application field of PPI ZnO structures as a templates. - Abstract: Position controlled single crystalline ZnO nanowires are grown on periodically polarity-inverted (PPI) ZnO heterostructures without catalyst. PPI ZnO templates were fabricated by using selective growth method of polarity with Cr-compound intermediate layers by plasma assisted molecular beam epitaxy. In order to control the position, we used the in-plane two-dimensionally discrete PPI ZnO templates. The lateral polarity inversion in PPI template was confirmed by piezo response microscopy. After syntheses of ZnO nanowires, vertically aligned ZnO nanowires were grown only onto the Zn-polar regions without the O-polar regions. The results clearly show that the position control of ZnO nanowires is possible using the PPI ZnO templates.

  17. Large-area aligned growth of single-crystalline organic nanowire arrays for high-performance photodetectors

    International Nuclear Information System (INIS)

    Due to their extraordinary properties, single-crystalline organic nanowires (NWs) are important building blocks for future low-cost and efficient nano-optoelectronic devices. However, it remains a critical challenge to assemble organic NWs rationally in an orientation-, dimensionality- and location-controlled manner. Herein, we demonstrate a feasible method for aligned growth of single-crystalline copper phthalocyanine (CuPc) NW arrays with high density, large-area uniformity and perfect crossed alignment by using Au film as a template. The growth process was investigated in detail. The Au film was found to have a critical function in the aligned growth of NWs, but may only serve as the active site for NW nucleation because of the large surface energy, as well as direct the subsequent aligned growth. The as-prepared NWs were then transferred to construct single NW-based photoconductive devices, which demonstrated excellent photoresponse properties with robust stability and reproducibility; the device showed a high switching ratio of ∼180, a fast response speed of ∼100 ms and could stand continuous operation up to 2 h. Importantly, this strategy can be extended to other organic molecules for their synthesis of NW arrays, revealing great potential for use in the construction of large-scale high-performance functional nano-optoelectronic devices. (paper)

  18. Highly mesoporous single-crystalline zeolite beta synthesized using a nonsurfactant cationic polymer as a dual-function template

    KAUST Repository

    Zhu, Jie

    2014-02-12

    Mesoporous zeolites are useful solid catalysts for conversion of bulky molecules because they offer fast mass transfer along with size and shape selectivity. We report here the successful synthesis of mesoporous aluminosilicate zeolite Beta from a commercial cationic polymer that acts as a dual-function template to generate zeolitic micropores and mesopores simultaneously. This is the first demonstration of a single nonsurfactant polymer acting as such a template. Using high-resolution electron microscopy and tomography, we discovered that the resulting material (Beta-MS) has abundant and highly interconnected mesopores. More importantly, we demonstrated using a three-dimensional electron diffraction technique that each Beta-MS particle is a single crystal, whereas most previously reported mesoporous zeolites are comprised of nanosized zeolitic grains with random orientations. The use of nonsurfactant templates is essential to gaining single-crystalline mesoporous zeolites. The single-crystalline nature endows Beta-MS with better hydrothermal stability compared with surfactant-derived mesoporous zeolite Beta. Beta-MS also exhibited remarkably higher catalytic activity than did conventional zeolite Beta in acid-catalyzed reactions involving large molecules. © 2014 American Chemical Society.

  19. Unit-Cell by Unit-Cell Homoepitaxial Growth Using Atomically Flat SrTiO3(001) Substrates and Pulsed Laser Deposition

    Institute of Scientific and Technical Information of China (English)

    FEI Yi-Yan; WANG Xu; LU Hui-Bin; YANG Guo-Zhen; ZHU Xiang-Dong

    2005-01-01

    @@ Using a combination of chemical etching and thermal annealing methods, we have obtained atomically flat TiO2-terminated SrTiO3 (001) with large terraces.The average width of the terrace is only determined by miscut angles.When we continuously grow tens of SrTiO3 monolayers on such a surface under pulsed laser ablation deposition condition at 621℃, the growth proceeds in a layer-by-layer mode characterized by un-damped oscillations of the specular RHEED intensity.After the growth of 180 monolayers, the surface morphology is restored to the pre-growth condition with similarly large terraces after annealing in vacuum for only 30 min, indicating efficient mass transfer on TiO2-terminated terraces.

  20. Single crystalline monoclinic La0.7Sr0.3MnO3 nanowires with high temperature ferromagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Carretero-Genevrier, Adrian [ICMAB, Barcelona, Spain; Gazquez Alabart, Jaume [ORNL; Idrobo Tapia, Juan C [ORNL; Oro, Judith [ICMAB, Barcelona, Spain; Arbiol, Jordi [ICMAB, Barcelona, Spain; Varela del Arco, Maria [ORNL; Ferain, Etienne [Universite catholique de Louvain, Belgium (UCL); Rodriguez-Carvajal, Juan [Institut Laue-Langevin (ILL); Puig, Teresa [ICMAB, Barcelona, Spain; Mestres, Narcis [ICMAB, Barcelona, Spain; Obradors, Xavier [ICMAB, Barcelona, Spain

    2011-01-01

    Porous mixed-valent manganese oxides are a group of multifunctional materials that can be used as molecular sieves, catalysts, battery materials, and gas sensors. However, material properties and thus activity can vary significantly with different synthesis methods or process conditions, such as temperature and time. Here, we report on a new synthesis route for MnO{sub 2} and LaSr-doped molecular sieve single crystalline nanowires based on a solution chemistry methodology combined with the use of nanoporous polymer templates supported on top of single crystalline substrates. Because of the confined nucleation in high aspect ratio nanopores and of the high temperatures attained, new structures with novel physical properties have been produced. During the calcination process, the nucleation and crystallization of {var_epsilon}-MnO{sub 2} nanoparticles with a new hexagonal structure is promoted. These nanoparticles generated up to 30 {mu}m long and flexible hexagonal nanowires at mild growth temperatures (T{sub g} = 700 C) as a consequence of the large crystallographic anisotropy of {var_epsilon}-MnO{sub 2}. The nanocrystallites of MnO{sub 2} formed at low temperatures serve as seeds for the growth of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanowires at growth temperatures above 800 C, through the diffusion of La and Sr into the empty 1D-channels of {var_epsilon}-MnO{sub 2}. Our particular growth method has allowed the synthesis of single crystalline molecular sieve (LaSr-2 x 4) monoclinic nanowires with composition La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and with ordered arrangement of La{sup 3+} and Sr{sup 2+} cations inside the 1D-channels. These nanowires exhibit ferromagnetic ordering with strongly enhanced Curie temperature (T{sub c} > 500 K) that probably results from the new crystallographic order and from the mixed valence of manganese.

  1. Phase identification on the intermetallic compound formed between eutectic SnIn solder and single crystalline Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Feifei; Liu, Zhi-Quan, E-mail: zqliu@imr.ac.cn; Shang, Pan-Ju; Guo, Jingdong

    2014-04-05

    Graphical abstract: Two kinds of intermetallic compounds were formed in three sublayers during interfacial reaction between eutectic SnIn solder and single crystalline Cu substrate, which are Cu(In,Sn){sub 2} layer with tetragonal crystal structure at solder side, coarse-grain Cu{sub 2}(In,Sn) sublayer and fine-grain Cu{sub 2}(In,Sn) sublayer with hexagonal crystal structure at Cu side. -- Highlights: • Reflowing at 160 °C Cu(In,Sn){sub 2} and Cu{sub 2}(In,Sn) were formed on single crystalline Cu. • Large Cu(In,Sn){sub 2} grain has tetragonal crystal structure with chunk-type morphology. • Cu(In,Sn){sub 2} layer is prone of spalling into solder in liquid soldering process. • Cu{sub 2}(In,Sn) is made up of fine and coarse sublayers with hexagonal crystal structure. • Fine Cu{sub 2}(In,Sn) grain has granular morphology and coarse one is elongated. -- Abstract: The intermetallic compound (IMC) formed between eutectic SnIn solder and single crystalline Cu substrate during reflow and solid-state aging was investigated precisely utilizing electron microscope. Two kinds of crystal structures with different morphologies were identified, which are Cu(In,Sn){sub 2} at the solder side and the Cu{sub 2}(In,Sn) at the Cu substrate side. The Cu(In,Sn){sub 2} layer with chunk-type morphology suffered spalling easily during slightly increased liquid soldering at 160 °C, and Cu{sub 2}(In,Sn) was in the form of duplex structure with coarse-grain and fine-grain sublayers. During solid-state aging at 60 °C, the morphology of fine-grain Cu{sub 2}(In,Sn) kept granule-type, while that of the coarse-grain Cu{sub 2}(In,Sn) was substrate-dependent with elongated morphology.

  2. Constructing MnO2/single crystalline ZnO nanorod hybrids with enhanced photocatalytic and antibacterial activity

    Science.gov (United States)

    Yu, Weiwei; Liu, Tiangui; Cao, Shiyi; Wang, Chen; Chen, Chuansheng

    2016-07-01

    In order to improve the photocatalytic and antibacterial activity of ZnO nanorods, ZnO nanorods decorated with MnO2 nanoparticles (MnO2/ZnO nanorod hybrids) were prepared by using microwave assisted coprecipitation method under the influence of hydrogen peroxide, and the structure, photocatalytic activity and antibacterial property of the products were studied. Experimental results indicated that MnO2 nanoparticles are decorated on the surface of single crystalline ZnO nanorods. Moreover, the resultant MnO2/ZnO nanorod hybrids have been proven to possess good photocatalytic and antibacterial activity, which their degradated efficiency for Rhodamin B (RhB) is twice as the pure ZnO nanorods. Enhancement for photocatalytic and antibacterial activity is mainly attributed to the low band gap energy and excellent electrochemical properties of MnO2 nanoparticles.

  3. Cobalt-doping effects in single crystalline and polycrystalline EuFe2-xCoxAs2 compounds

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A series of Co-doped EuFe2-xCoxAs2 compounds were prepared in both of single crystalline and polycrystalline forms.The Co-doping effects on the crystal structure,electrical resistivity and magnetic susceptibility were systematically studied.Superconductivity was found in polycrystalline Co-doped samples from zero resistivity effects,with the highest onset superconducting transition temperature at 26 K in the optimum doped EuFe1.84Co0.16As2 compound.While due to the stronger competition between the superconducting order and the Eu2+ magnetic order,the zero resistivity effect is absent in the Co-doped single crystal samples.

  4. The unusually high Tc in rare-earth-doped single crystalline CaFe2As2

    Science.gov (United States)

    Wei, Fengyan; Lv, Bing; Deng, Liangzi; Meen, James K.; Xue, Yu-Yi; Chu, Ching-Wu

    2014-08-01

    In rare-earth-doped single crystalline CaFe2As2, the mysterious small volume fraction which superconducts up to 49 K, much higher than the bulk Tc ~ 30 s K, has prompted a long search for a hidden variable that could enhance the Tc by more than 30% in iron-based superconductors of the same structure. Here we report a chemical, structural and magnetic study of CaFe2As2 systematically doped with La, Ce, Pr and Nd. Coincident with the high Tc phase, we find extreme magnetic anisotropy, accompanied by an unexpected doping-independent Tc and equally unexpected superparamagnetic clusters associated with As vacancies. These observations lead us to conjecture that the tantalizing Tc enhancement may be associated with naturally occurring chemical interfaces and may thus provide a new paradigm in the search for superconductors with higher Tc.

  5. Synthesis of single-crystalline hollow β-FeOOH nanorods via a controlled incomplete-reaction course

    International Nuclear Information System (INIS)

    The single-crystalline β-FeOOH hollow nanorods with a diameter ranging from 20∼30 nm and length in the range of 70-110 nm have been successfully synthesized through a two-step route in the solution. The phase transformation and the morphologies of the hollow β-FeOOH nanorods were investigated with X-ray powdered diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electric diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), infrared spectrum (IR) and thermo-gravimetric analysis (TGA). These studies indicate that the first step is an incomplete-reaction course. Furthermore, The formation mechanism of the hollow nanorods has been discussed. It is found that the mixed system including chitosan and n-propanol is essential for the final formation of the hollow β-FeOOH nanorods

  6. The modulation of surface texture for single-crystalline Si solar cells using calibrated silver nanoparticles as a catalyst

    International Nuclear Information System (INIS)

    We have employed Ag nanoparticles with calibrated size as catalysts to modulate the surface texture of single-crystalline Si surfaces for reducing sunlight reflectivity. Both experiments and theoretical analysis have proved that a well-organized microporous structure on the pyramids can be obtained by optimizing the size of Ag nanoparticles and the texturing time, and the Si wafer with such structures can effectively reduce the reflectivity of sunlight. However, based on the conventional cell fabrication process, the performance of silicon solar cells with such microporous structures gets degraded. It is closely associated with the strong surface recombination and the high phosphorus diffusion barrier induced by the microporous textures. These results are interesting for us to understand the application of nanotechnology on the silicon solar cell.

  7. Environmentally friendly growth of single-crystalline K2Ti6O13 nanoribbons from KCl flux

    International Nuclear Information System (INIS)

    Single-crystalline K2Ti6O13 nanoribbons with typical width ranging from one hundred nanometers to a few hundred nanometers and length up to tens of microns were prepared from KCl flux. The nanoribbons were characterized by a range of methods including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, selected area electron diffraction and high-resolution transmission electron microscopy. Ultraviolet-visible experiments showed that the K2Ti6O13 nanoribbons were wide-band semiconductors with a band width Eg = 3.4 eV. The mechanism of one-dimensional growth of the nanoribbons was attributed to the oriented attachment mechanism.

  8. Features of static and dynamic friction profiles in one and two dimensions on polymer and atomically flat surfaces using atomic force microscopy

    International Nuclear Information System (INIS)

    In this paper we correlate the Atomic Force Microscope probe movement with surface location while scanning in the imaging and Force versus distance modes. Static and dynamic stick-slip processes are described on a scale of nanometres to microns on a range of samples. We demonstrate the limits and range of the tip apex being fixed laterally in the force versus distance mode and static friction slope dependence on probe parameters. Micron scale static and dynamic friction can be used to purposefully manipulate soft surfaces to produce well defined frictional gradients

  9. Construction of single-crystalline supramolecular networks of perchlorinated hexa-peri-hexabenzocoronene on Au(111).

    Science.gov (United States)

    Zhang, Yi; Zhang, Yanfang; Li, Geng; Lu, Jianchen; Lin, Xiao; Tan, Yuanzhi; Feng, Xinliang; Du, Shixuan; Müllen, Klaus; Gao, Hong-Jun

    2015-03-14

    The self-assembly of the perchlorinated hexa-peri-hexabenzocoronene (PCHBC) molecules on Au(111) has been studied by a low temperature scanning tunneling microscopy (STM) combining with density functional theory based first principle calculations. Highly ordered supramolecular networks with single domains limited by the terraces are formed on Au(111) substrate. High resolution images of the PCHBC molecules, confirmed by first principle simulations, are obtained. It reveals the close-packed arrangement of the PCHBC molecules on Au(111). The calculated charge distribution of PCHBC molecules shows the existence of attractive halogen-halogen interaction between neighboring molecules. Compared with the disordered adsorption of hexa-peri-hexabenzocoronene on Au(111), we conclude that the formation of attractive Cl∙∙∙Cl interactions between neighbors is the key factor to form the highly ordered, close-packed networks. Due to the steric hindrance resulted from the peripheral chlorine atoms, the PCHBC molecule is contorted and forms the doubly concave conformation, which is different from the hexa-peri-hexabenzocoronene with a planar structure. By using this supramolecular network as a template, we deposited C60 molecules on it at room temperature with low coverage. The STM images taken at low temperature show that the C60 molecules are mono-dispersed on the networks and adsorb on top of the PCHBC molecules, forming a typical concave-convex host-guest system. PMID:25770500

  10. Construction of single-crystalline supramolecular networks of perchlorinated hexa-peri-hexabenzocoronene on Au(111)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yi; Zhang, Yanfang; Li, Geng; Lu, Jianchen; Du, Shixuan, E-mail: sxdu@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn; Gao, Hong-Jun, E-mail: sxdu@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn [Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China); Lin, Xiao [University of Chinese Academy of Sciences and Institute of Physics, Chinese Academy of Sciences, Beijing 100049 (China); Tan, Yuanzhi [Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany); Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Feng, Xinliang [Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany); School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Müllen, Klaus [Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany)

    2015-03-14

    The self-assembly of the perchlorinated hexa-peri-hexabenzocoronene (PCHBC) molecules on Au(111) has been studied by a low temperature scanning tunneling microscopy (STM) combining with density functional theory based first principle calculations. Highly ordered supramolecular networks with single domains limited by the terraces are formed on Au(111) substrate. High resolution images of the PCHBC molecules, confirmed by first principle simulations, are obtained. It reveals the close-packed arrangement of the PCHBC molecules on Au(111). The calculated charge distribution of PCHBC molecules shows the existence of attractive halogen–halogen interaction between neighboring molecules. Compared with the disordered adsorption of hexa-peri-hexabenzocoronene on Au(111), we conclude that the formation of attractive ClCl interactions between neighbors is the key factor to form the highly ordered, close-packed networks. Due to the steric hindrance resulted from the peripheral chlorine atoms, the PCHBC molecule is contorted and forms the doubly concave conformation, which is different from the hexa-peri-hexabenzocoronene with a planar structure. By using this supramolecular network as a template, we deposited C{sub 60} molecules on it at room temperature with low coverage. The STM images taken at low temperature show that the C{sub 60} molecules are mono-dispersed on the networks and adsorb on top of the PCHBC molecules, forming a typical concave-convex host-guest system.

  11. Scanning Tunneling Microscopy study of single-crystalline Sr3Ru2O7

    International Nuclear Information System (INIS)

    Full text: Perovskite oxides play an important role as cathodes in solid oxide fuel cells (SOFC) and in catalysis. Investigating surface defects such as oxygen vacancies and the adsorption of relevant molecules helps gaining more insight into the physics behind SOFCs and catalytic processes. High quality Sr3Ru2O7 (SRO) single crystals were grown using the floating zone technique. The SRO samples were cleaved at 150 K under UHV conditions and subsequently investigated by STM at 78 K and 6 K. To determine which species are imaged in STM, doped SRO samples were investigated and STM simulations were performed. Furthermore, we have characterized the defects that are present at the as-cleaved surfaces, and how reactive they are if exposed to CO and O2. STM shows that CO binds to some defects at the surface and, possibly, also to apical oxygen atoms at the perfect surface. The interaction between the clean surface and CO was also investigated by DFT calculations. (author)

  12. Construction of single-crystalline supramolecular networks of perchlorinated hexa-peri-hexabenzocoronene on Au(111)

    International Nuclear Information System (INIS)

    The self-assembly of the perchlorinated hexa-peri-hexabenzocoronene (PCHBC) molecules on Au(111) has been studied by a low temperature scanning tunneling microscopy (STM) combining with density functional theory based first principle calculations. Highly ordered supramolecular networks with single domains limited by the terraces are formed on Au(111) substrate. High resolution images of the PCHBC molecules, confirmed by first principle simulations, are obtained. It reveals the close-packed arrangement of the PCHBC molecules on Au(111). The calculated charge distribution of PCHBC molecules shows the existence of attractive halogen–halogen interaction between neighboring molecules. Compared with the disordered adsorption of hexa-peri-hexabenzocoronene on Au(111), we conclude that the formation of attractive ClCl interactions between neighbors is the key factor to form the highly ordered, close-packed networks. Due to the steric hindrance resulted from the peripheral chlorine atoms, the PCHBC molecule is contorted and forms the doubly concave conformation, which is different from the hexa-peri-hexabenzocoronene with a planar structure. By using this supramolecular network as a template, we deposited C60 molecules on it at room temperature with low coverage. The STM images taken at low temperature show that the C60 molecules are mono-dispersed on the networks and adsorb on top of the PCHBC molecules, forming a typical concave-convex host-guest system

  13. Flower-like hierarchical structures consisting of porous single-crystalline ZnO nanosheets and their gas sensing properties to volatile organic compounds (VOCs)

    International Nuclear Information System (INIS)

    Highlights: • Flower-like hierarchical structures consisting of porous single-crystalline ZnO nanosheets were synthesized. • The flower-like hierarchical structured ZnO exhibited higher response and shorter response and recovery times. • The sensing mechanism of the flower-like hierarchical has been systematically analyzed. - Abstract: Flower-like hierarchical structures consisting of porous single-crystalline ZnO nanosheets (FHPSCZNs) were synthesized by a one-pot wet-chemical method followed by an annealing treatment, which combined the advantages between flower-like hierarchical structure and porous single-crystalline structure. XRD, SEM and HRTEM were used to characterize the synthesized FHPSCZN samples. The sensing properties of the FHPSCZN sensor were also investigated by comparing with ZnO powder sensor, which exhibited higher response and shorter response and recovery times. The sensing mechanism of the FHPSCZN sensor has been further analyzed from the aspects of electronic transport and gas diffusion

  14. Defect evolution in single crystalline tungsten following low temperature and low dose neutron irradiation

    Science.gov (United States)

    Hu, Xunxiang; Koyanagi, Takaaki; Fukuda, Makoto; Katoh, Yutai; Snead, Lance L.; Wirth, Brian D.

    2016-03-01

    The tungsten plasma-facing components of fusion reactors will experience an extreme environment including high temperature, intense particle fluxes of gas atoms, high-energy neutron irradiation, and significant cyclic stress loading. Irradiation-induced defect accumulation resulting in severe thermo-mechanical property degradation is expected. For this reason, and because of the lack of relevant fusion neutron sources, the fundamentals of tungsten radiation damage must be understood through coordinated mixed-spectrum fission reactor irradiation experiments and modeling. In this study, high-purity (110) single-crystal tungsten was examined by positron annihilation spectroscopy and transmission electron microscopy following low-temperature (∼90 °C) and low-dose (0.006 and 0.03 dpa) mixed-spectrum neutron irradiation and subsequent isochronal annealing at 400, 500, 650, 800, 1000, 1150, and 1300 °C. The results provide insights into microstructural and defect evolution, thus identifying the mechanisms of different annealing behavior. Following 1 h annealing, ex situ characterization of vacancy defects using positron lifetime spectroscopy and coincidence Doppler broadening was performed. The vacancy cluster size distributions indicated intense vacancy clustering at 400 °C with significant damage recovery around 1000 °C. Coincidence Doppler broadening measurements confirm the trend of the vacancy defect evolution, and the S-W plots indicate that only a single type of vacancy cluster is present. Furthermore, transmission electron microscopy observations at selected annealing conditions provide supplemental information on dislocation loop populations and visible void formation. This microstructural information is consistent with the measured irradiation-induced hardening at each annealing stage, providing insight into tungsten hardening and embrittlement due to irradiation-induced matrix defects.

  15. Metallic ground state and glassy transport in single crystalline URh2Ge2: enhancement of disorder effects in a strongly correlated electron system.

    Science.gov (United States)

    Süllow, S; Maksimov, I; Otop, A; Litterst, F J; Perucchi, A; Degiorgi, L; Mydosh, J A

    2004-12-31

    We present a detailed study of the electronic transport properties on a single crystalline specimen of the moderately disordered heavy-fermion system URh2Ge2. For this material, we find glassy electronic transport in a single crystalline compound. We derive the temperature dependence of the electrical conductivity and establish metallicity by means of optical conductivity and Hall effect measurements. The overall behavior of the electronic transport properties closely resembles that of metallic glasses, with at low temperatures an additional minor spin disorder contribution. We argue that this glassy electronic behavior in a crystalline compound reflects the enhancement of disorder effects as a consequence of strong electronic correlations. PMID:15698001

  16. Ti3+-self doped brookite TiO2 single-crystalline nanosheets with high solar absorption and excellent photocatalytic CO2 reduction.

    Science.gov (United States)

    Xin, Xiaoye; Xu, Tao; Wang, Lan; Wang, Chuanyi

    2016-01-01

    Black brookite TiO2 single-crystalline nanosheets with outstanding photocatalytic activity toward CO2 reduction is prepared by a facile oxidation-based hydrothermal reaction method combined with post-annealing treatment. Large amount of Ti(3+) defects are introduced into the bulk of brookite nanoparticles, which increases the solar energy absorption and enhances the photocatalytic activity. PMID:27021203

  17. Ti3+-self doped brookite TiO2 single-crystalline nanosheets with high solar absorption and excellent photocatalytic CO2 reduction

    OpenAIRE

    Xiaoye Xin; Tao Xu; Lan Wang; Chuanyi Wang

    2016-01-01

    Black brookite TiO2 single-crystalline nanosheets with outstanding photocatalytic activity toward CO2 reduction is prepared by a facile oxidation-based hydrothermal reaction method combined with post-annealing treatment. Large amount of Ti3+ defects are introduced into the bulk of brookite nanoparticles, which increases the solar energy absorption and enhances the photocatalytic activity.

  18. Photoluminescence and excited state structure in Bi.sup.3+./sup.-doped Y.sub.2./sub.SiO.sub.5./sub. single crystalline films

    Czech Academy of Sciences Publication Activity Database

    Babin, Vladimir; Gorbenko, V.; Krasnikov, A.; Mihóková, Eva; Nikl, Martin; Zazubovich, S.; Zorenko, Y.

    2013-01-01

    Roč. 56, Sept (2013), s. 90-93. ISSN 1350-4487 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : luminescence * Bi 3+ -doped oxyorthosilicates * single crystalline films Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.140, year: 2013

  19. Luminescent properties and energy transfer processes in Ce-Tb doped single crystalline film screens of Lu-based silicate, perovskite and garnet compounds

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Zorenko, T.; Martin, T.; Douissard, P.-A.; Nikl, Martin; Mareš, Jiří A.

    2013-01-01

    Roč. 56, Sept (2013), s. 415-419. ISSN 1350-4487 Institutional support: RVO:68378271 Keywords : single crystalline films * liquid phase epitaxy * perovskite s * luminescence * scintillators Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.140, year: 2013

  20. Facile synthesis of porous single crystalline ZnO nanoplates and their application in photocatalytic reduction of Cr(VI) in the presence of phenol

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Zhen [Research Center for Biomimetic Functional Materials and Sensing Devices, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Zhang, Yong-Xing [School of Physics and Electronic Information, Huaibei Normal University, Huaibei, Anhui 235000 (China); Meng, Fan-Li; Jia, Yong; Luo, Tao; Yu, Xin-Yao; Wang, Jin; Liu, Jin-Huai [Research Center for Biomimetic Functional Materials and Sensing Devices, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Xing-Jiu, E-mail: xingjiuhuang@iim.ac.cn [Research Center for Biomimetic Functional Materials and Sensing Devices, Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2014-07-15

    Graphical abstract: - Highlights: • Porous single crystalline ZnO nanoplates were successfully synthesized. • The nanoplates were with 12 nm in thickness and tens nanometers in pore size. • A synergistic effect of enhanced Cr(VI) photoreduction and phenol degradation was observed. • A possible reaction mechanism was discussed. - Abstract: Porous single crystalline ZnO nanoplates were successfully synthesized through a facile and cost-effective hydrothermal process at low temperature condition, followed by annealing of the zinc carbonate hydroxide hydrate precursors. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) measurements. The porous single crystalline ZnO nanoplates are with 12 nm thickness and pore ranging from 10 nm to several tens of nanometers. The porous structure of the ZnO nanoplates caused large amount of surface defects which worked as photogenerated holes’ shallow trappers and largely restrained the recombination of photogenerated electrons and holes, resulting in a significantly high photocatalytic activity and durability toward the photoreduction of Cr(VI) under UV irradiation. Moreover, a synergistic effect, that is, increased photocatalytic reduction of Cr(VI) and degradation of phenol, can be observed. Furthermore, the synergistic photocatalytic mechanism has also been discussed. Those results present an enlightenment to employ porous single crystalline nanomaterials to remove Cr(VI) and organic pollutants simultaneously.

  1. Creation of atomically flat Si{111}7 × 7 side-surfaces on a three-dimensionally-architected Si(110) substrate

    Science.gov (United States)

    Hattori, Azusa N.; Hattori, Ken; Takemoto, Shohei; Daimon, Hiroshi; Tanaka, Hidekazu

    2016-02-01

    The realization of atomically flat side-surfaces, which are vertical planes on a substrate, would make an enormous contribution to a paradigm shift from two-dimensional planar film structures to three-dimensional (3D) nanostructures. In this paper, we demonstrate the successful creation of well-defined Si{111}7 × 7 side-surfaces on a 3D-architected Si(110) substrate by the combination of 3D Si patterning and surface preparation techniques, as confirmed by reflection high-energy electron diffraction (RHEED). The RHEED patterns consisted of 7 × 7 diffraction spots from the Si{111} side-surfaces and 2 × 16 diffraction spots from the Si(110) top/bottom surface. We also performed the deposition of metals (Au and Ag) onto the side-surfaces, leading to the formation of Si(1 bar 11) √3 × √3R30°-Au and Si(1 1 bar 1 bar) √3 × √3R30°-Ag structures. This is the first demonstration indicating super-reconstructions of such well-defined side-surfaces.

  2. Direct Observation of Defect Range and Evolution in Ion-Irradiated Single Crystalline Ni and Ni Binary Alloys

    Science.gov (United States)

    Lu, Chenyang; Jin, Ke; Béland, Laurent K.; Zhang, Feifei; Yang, Taini; Qiao, Liang; Zhang, Yanwen; Bei, Hongbin; Christen, Hans M.; Stoller, Roger E.; Wang, Lumin

    2016-02-01

    Energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters far exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance.

  3. Morphological evolution in single-crystalline Bi2Te3 nanoparticles, nanosheets and nanotubes with different synthesis temperatures

    Indian Academy of Sciences (India)

    Punita Srivastava; Kedar Singh

    2013-10-01

    A general surfactant-assisted wet chemical route has been developed for the synthesis of a variety of bismuth telluride (Bi2Te3) single-crystalline nanostructures with varied morphologies at different temperatures in which hydrazine hydrate plays as an important solvent. Bi2Te3 sheet grown nanoparticles, nanosheets and nanotubes have been synthesized by a simplest wet chemical route at 50, 70 and 100 °C within 4 h. Bi2Te3 sheet grown nanoparticles are obtained in agglomerate state and they are found with many wrinkles. Various types of Bi2Te3 nanotubes are also found which are tapered with one end open and the other closed. X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) pattern and energy dispersive X-ray (EDX) spectroscopy were employed to characterize the powder product. It is found that all nanoparticles, nanosheets and nanotubes are well-crystallized nanocrystals and morphologies of the powder products are greatly affected by different synthesis temperatures. The formation mechanisms of bismuth telluride nanostructures are also discussed.

  4. Near Edge X-ray Absorption Fine Structure Spectroscopy Studies of Single-Crystalline V2O5 Nanowire Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Velazquez, J.; Jaye, C; Fischer, D; Banerjee, S

    2009-01-01

    Near edge X-ray absorption fine structure (NEXAFS) spectroscopy is used to precisely probe the alignment, uniformity in crystal growth direction, and electronic structure of single-crystalline V2O5 nanowire arrays prepared by a cobalt-catalyzed vapor transport process. The dipole selection rules operational for core-level electron spectroscopy enable angle-dependent NEXAFS spectroscopy to be used as a sensitive probe of the anisotropy of these systems and provides detailed insight into bond orientation and the symmetry of the frontier orbital states. The experimental spectra are matched to previous theoretical predictions and allow experimental verification of features such as the origin of the split-off conduction band responsible for the semiconducting properties of V2O5 and the strongly anisotropic nature of vanadyl-oxygen-derived (VO) states thought to be involved in catalysis. The strong anisotropy observed across thousands of nanowires in the NEXAFS measurements clearly demonstrates the uniformity of crystal growth direction in these nanowire arrays.

  5. Unusually high critical current of clean P-doped BaFe2As2 single crystalline thin film

    International Nuclear Information System (INIS)

    Microstructurally clean, isovalently P-doped BaFe2As2 (Ba-122) single crystalline thin films have been prepared on MgO (001) substrates by molecular beam epitaxy. These films show a superconducting transition temperature (Tc) of over 30 K although P content is around 0.22, which is lower than the optimal one for single crystals (i.e., 0.33). The enhanced Tc at this doping level is attributed to the in-plane tensile strain. The strained film shows high transport self-field critical current densities (Jc) of over 6 MA/cm2 at 4.2 K, which are among the highest for Fe based superconductors (FeSCs). In-field Jc exceeds 0.1 MA/cm2 at μ0H=35 T for H‖ab and μ0H=18 T for H‖c at 4.2 K, respectively, in spite of moderate upper critical fields compared to other FeSCs with similar Tc. Structural investigations reveal no defects or misoriented grains pointing to strong pinning centers. We relate this unexpected high Jc to a strong enhancement of the vortex core energy at optimal Tc, driven by in-plane strain and doping. These unusually high Jc make P-doped Ba-122 very favorable for high-field magnet applications

  6. Application of single-crystalline PMN-PT and PIN-PMN-PT in high-performance pyroelectric detectors.

    Science.gov (United States)

    Yu, Ping; Ji, Yadong; Neumann, Norbert; Lee, Sang-Goo; Luo, Hasou; Es-Souni, Mohammed

    2012-09-01

    The suitability for use in pyroelectric detectors of single-crystalline doped and undoped lead indium niobate-lead magnesium niobate-lead titanate was tested and compared with high-quality Mn-doped lead magnesium niobate-lead titanate and standard lithium tantalate. Pyroelectric and dielectric measurements confirmed an increased processing and operating temperature range because of the higher phase transitions of lead indium niobate-lead magnesium niobate-lead titanate. Pyroelectric coefficients of 705 to 770 μC/m(2)K were obtained with doped and undoped lead indium niobate-lead magnesium niobate-lead titanate, which are about 70% to 80% of the pyroelectric coefficient of lead magnesium niobate-lead titanate but 4 times higher than standard lithium tantalate. Manganese doping has been proved as a solution to decrease the dielectric loss of lead magnesium niobate-lead titanate and it also works well for lead indium niobate-lead magnesium niobate-lead titanate. An outstanding specific detectivity D* of about 1.1 · 10(9) cm·Hz(1/2)/W was achieved at a frequency of 2 Hz for Mn-doped lead magnesium niobate-based detectors. PMID:23007771

  7. Synthesis of ternary Ni{sub 1−x}Fe{sub x}S single crystalline nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Xiaoying [College of Physical Science and Technology, Xinjiang University, Urumqi 830046, Xinjiang (China); Zhang, Zhihua [Liaoning Key Materials Laboratory for Railway, School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028 (China); Wu, Rong; Li, Jin [College of Physical Science and Technology, Xinjiang University, Urumqi 830046, Xinjiang (China); Jian, Jikang, E-mail: jikangjian@gmail.com [College of Physical Science and Technology, Xinjiang University, Urumqi 830046, Xinjiang (China)

    2014-12-05

    Highlights: • Ternary Ni{sub 1−x}Fe{sub x}S single-crystal nanorods were synthesized by a solvothermal technique. • Crystal structures, morphology and compositions of the ternary nanorods were characterized in details. • The band gaps of the Ni{sub 1−x}Fe{sub x}S nanorods were determined by optical absorption test. - Abstract: Single-crystalline Fe-doped NiS ternary nanorods with uniform morphology have been successfully synthesized in ethylenediamine solvent by a solvothermal technique using Ni, S and FeCl{sub 2}⋅4H{sub 2}O as starting materials. The phase, morphology, compositions and microstructure of the products have been characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The results show that the Ni{sub 1−x}Fe{sub x}S nanorods are well crystallized and the highest Fe doping concentration x is about 17.51%. The addition of Fe{sup 2+} ions can facilitate the one-dimensional growth and enlarge the band gaps of the nanorods.

  8. Temperature dependent exchange bias training effect in single-crystalline BiFeO3/Co bilayers

    International Nuclear Information System (INIS)

    Single-crystalline BiFeO3 (BFO)/Co bilayers were prepared by combined pulsed laser deposition and magnetron sputtering on (001) SrTiO3 substrates. Exchange bias (EB) and accompanying training effect have been studied as a function of temperature (T) between 5 K and 300 K. A non-monotonic exchange field variation with sharp increase below 100 K has been observed. In the meanwhile, strong training effect was recorded when T < 100 K and it weakens monotonically with increasing T up to 300 K. These temperature dependent EB and training effect may be caused by the uncompensated spins in both the interfacial spin-glass (SG) phase at low temperature and the antiferromagnetic BFO layer at higher temperature. The low temperature EB training results can be well fitted by a modified Binek's model considering asymmetric changes of the pinning SG spins at the descending and the ascending branches

  9. Shape- and dimension-controlled single-crystalline silicon and SiGe nanotubes: toward nanofluidic FET devices.

    Science.gov (United States)

    Ben Ishai, Moshit; Patolsky, Fernando

    2009-03-18

    We report here on the formation of robust and entirely hollow single-crystalline silicon nanotubes, from various tubular to conical structures, with uniform and well-controlled inner diameter, ranging from as small as 1.5 up to 500 nm, and controllable wall thickness. Second, and most important, these nanotubes can be doped in situ with different concentrations of boron and phosphine to give p/n-type semiconductor nanotubes. Si(x)Ge(1-x)-alloy nanotubes can also be prepared. This synthetic approach enables independent and precise control of diameter, wall thickness, shape, taper angle, crystallinity, and chemical/electrical characteristics of the nanotubular structures obtained. Notably, diameter and wall thickness of nearly any size can be obtained. This unique advantage allows the achievement of novel and perfectly controlled high-quality electronic materials and the tailoring of the tube properties to better fit many biological, chemical, and electrical applications. Electrical devices based on this new family of electrically active nanotubular building-block structures are also described with a view toward the future realization of nanofluidic FET devices. PMID:19226180

  10. Atoms

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  11. Atoms

    International Nuclear Information System (INIS)

    Completed by recent contributions on various topics (atoms and the Brownian motion, the career of Jean Perrin, the evolution of atomic physics since Jean Perrin, relationship between scientific atomism and philosophical atomism), this book is a reprint of a book published at the beginning of the twentieth century in which the author addressed the relationship between atomic theory and chemistry (molecules, atoms, the Avogadro hypothesis, molecule structures, solutes, upper limits of molecular quantities), molecular agitation (molecule velocity, molecule rotation or vibration, molecular free range), the Brownian motion and emulsions (history and general features, statistical equilibrium of emulsions), the laws of the Brownian motion (Einstein's theory, experimental control), fluctuations (the theory of Smoluchowski), light and quanta (black body, extension of quantum theory), the electricity atom, the atom genesis and destruction (transmutations, atom counting)

  12. Well-Defined Nanostructured, Single-Crystalline TiO2 Electron Transport Layer for Efficient Planar Perovskite Solar Cells.

    Science.gov (United States)

    Choi, Jongmin; Song, Seulki; Hörantner, Maximilian T; Snaith, Henry J; Park, Taiho

    2016-06-28

    An electron transporting layer (ETL) plays an important role in extracting electrons from a perovskite layer and blocking recombination between electrons in the fluorine-doped tin oxide (FTO) and holes in the perovskite layers, especially in planar perovskite solar cells. Dense TiO2 ETLs prepared by a solution-processed spin-coating method (S-TiO2) are mainly used in devices due to their ease of fabrication. Herein, we found that fatal morphological defects at the S-TiO2 interface due to a rough FTO surface, including an irregular film thickness, discontinuous areas, and poor physical contact between the S-TiO2 and the FTO layers, were inevitable and lowered the charge transport properties through the planar perovskite solar cells. The effects of the morphological defects were mitigated in this work using a TiO2 ETL produced from sputtering and anodization. This method produced a well-defined nanostructured TiO2 ETL with an excellent transmittance, single-crystalline properties, a uniform film thickness, a large effective area, and defect-free physical contact with a rough substrate that provided outstanding electron extraction and hole blocking in a planar perovskite solar cell. In planar perovskite devices, anodized TiO2 ETL (A-TiO2) increased the power conversion efficiency by 22% (from 12.5 to 15.2%), and the stabilized maximum power output efficiency increased by 44% (from 8.9 to 12.8%) compared with S-TiO2. This work highlights the importance of the ETL geometry for maximizing device performance and provides insights into achieving ideal ETL morphologies that remedy the drawbacks observed in conventional spin-coated ETLs. PMID:27183030

  13. 两类扇形雾喷头雾化过程比较研究%Comparative research of two kinds of flat fan nozzle atomization process

    Institute of Scientific and Technical Information of China (English)

    谢晨; 何雄奎; 宋坚利; Andreas.Herbst

    2013-01-01

      为了探究标准扇形雾喷头(ST)与防飘喷头(IDK)的雾化特性,利用雾滴粒径分析仪(PDIA)对以上2种类型喷头的雾化过程进行了试验研究与可视化图形分析.结果表明:ST喷头具有面积较大的液膜区,且具有波纹结构,破裂区内的破裂孔洞呈现不规则撕裂状;IDK 喷头液膜区面积较 ST 喷头小,具有气泡状结构,但并未发现波纹区.随着ST与IDK喷头孔径的增大,液膜长度、破裂区长度分别由20 mm增长至40 mm、10 mm增长至20 mm.随着压力的增加,ST110-03型喷头的液膜长度由35 mm降低至22 mm,雾滴体积中径由128.2μm降低至92.4μm;IDK120-03型喷头的液膜-破裂区长度由40 mm降低至30 mm,雾滴体积中径由366.4μm降低至285.3μm.该研究可为进一步研究新型防飘喷头的雾化特性以及新型喷雾设备的生产提供参考.%The objectives of this research were to study the atomization characteristics of normal flat fan nozzles and air induction flat fan nozzles which were made by the LECHLER Company by a particle droplet image analysis system (PDIA) with visualized features. Images of ST110-03 and IDK120-03 nozzles’spraying fan from orifice to 30 mm below nozzle were taken at 0.3 MPa to observe the structure of the spraying fan. Spraying visualizations were conduct from 10 to 70 mm with the interval of 10 mm below the nozzle in the spraying fan centerline of ST110-01、02、03、04 and IDK120-01、02、03、04 at 0.3 MPa to analyze the influence of orifice width on spraying sheet length. To research the influence of spraying pressure on liquid sheet length and droplet size, spraying visualizations were performed from 10 to 70mm with the interval 10mm below the nozzle in the spraying fan centerline of ST110-03 and IDK120-03 at 0.2、0.3、0.4、0.5、0.6 MPa. The results showed that there was a larger liquid sheet in the ST110-03 spraying fan. It was very easy to observe the wave formation and irregular atomization

  14. Experimental evidence for self-assembly of CeO2 particles in solution: Formation of single-crystalline porous CeO2 nanocrystals

    DEFF Research Database (Denmark)

    Tan, Hui Ru; Tan, Joyce Pei Ying; Boothroyd, Chris;

    2012-01-01

    Single-crystalline porous CeO2 nanocrystals, with sizes of ∼20 nm and pore diameters of 1-2 nm, were synthesized successfully using a hydrothermal method. Using electron tomography, we imaged the three-dimensional structure of the pores in the nanocrystals and found that the oriented aggregation of...... small CeO2 nanoparticles resulted in the growth of CeO2 nanocrystals with an irregular truncated octahedral shape and pores extending along the 〈110〉 directions. Oxygen vacancies were found on the crystal surfaces and internal walls of the pores by scanning transmission electron microscopy and electron...... energy-loss spectroscopy. The oxygen vacancies might play an important role in oxygen diffusion in the crystals and the catalytic activities of single-crystalline porous CeO 2 structures. © 2011 American Chemical Society....

  15. Molecular-dynamics simulations of stacking-fault-induced dislocation annihilation in pre-strained ultrathin single-crystalline copper films

    OpenAIRE

    Kolluri, Kedarnath; Gungor, M. Rauf; Maroudas, Dimitrios

    2009-01-01

    We report results of large-scale molecular-dynamics (MD) simulations of dynamic deformation under biaxial tensile strain of pre-strained single-crystalline nanometer-scale-thick face-centered cubic (fcc) copper films. Our results show that stacking faults, which are abundantly present in fcc metals, may play a significant role in the dissociation, cross-slip, and eventual annihilation of dislocations in small-volume structures of fcc metals. The underlying mechanisms are mediated by interacti...

  16. Luminiscence of La.sup.3+./sup. and Sc.sup.3+./sup. impurity centers in YAlO.sub.3./sub. single-crystalline films

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.V.; Gorbenko, V.; Voznyak, T.; Zorenko, T.; Nikl, Martin; Nejezchleb, K.

    2008-01-01

    Roč. 128, č. 4 (2008), s. 595-602. ISSN 0022-2313 R&D Projects: GA ČR GA202/05/2471 Grant ostatní: INTAS(XE) 04-78-7083 Institutional research plan: CEZ:AV0Z10100521 Keywords : perovskites * single-crystalline films * luminiscence * excitons Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.628, year: 2008

  17. High mobility single-crystalline-like GaAs thin films on inexpensive flexible metal substrates by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, P., E-mail: pdutta2@central.uh.edu; Rathi, M.; Gao, Y.; Yao, Y.; Selvamanickam, V. [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); Zheng, N.; Ahrenkiel, P. [Department of Nanoscience and Nanoengineering, South Dakota School of Mines and Technology, Rapid City, South Dakota 57701 (United States); Martinez, J. [Materials Evaluation Laboratory, NASA Johnson Space Center, Houston, Texas 77085 (United States)

    2014-09-01

    We demonstrate heteroepitaxial growth of single-crystalline-like n and p-type doped GaAs thin films on inexpensive, flexible, and light-weight metal foils by metal-organic chemical vapor deposition. Single-crystalline-like Ge thin film on biaxially textured templates made by ion beam assisted deposition on metal foil served as the epitaxy enabling substrate for GaAs growth. The GaAs films exhibited strong (004) preferred orientation, sharp in-plane texture, low grain misorientation, strong photoluminescence, and a defect density of ∼10{sup 7 }cm{sup −2}. Furthermore, the GaAs films exhibited hole and electron mobilities as high as 66 and 300 cm{sup 2}/V-s, respectively. High mobility single-crystalline-like GaAs thin films on inexpensive metal substrates can pave the path for roll-to-roll manufacturing of flexible III-V solar cells for the mainstream photovoltaics market.

  18. Thermodynamic and transport properties of single crystalline RCo2Ge2 (R=Y, La–Nd, Sm–Tm)

    International Nuclear Information System (INIS)

    Single crystals of RCo2Ge2 (R=Y, La–Nd, Sm–Tm) were grown using a self-flux method and were characterized by room-temperature powder X-ray diffraction; anisotropic, temperature and field dependent magnetization; temperature and field dependent, in-plane resistivity; and specific heat measurements. In this series, the majority of the moment-bearing members order antiferromagnetically; YCo2Ge2 and LaCo2Ge2 are non-moment-bearing. Ce is trivalent in CeCo2Ge2 at high temperatures, and exhibits an enhanced electronic specific heat coefficient due to the Kondo effect at low temperatures. In addition, CeCo2Ge2 shows two low-temperature anomalies in temperature-dependent magnetization and specific heat measurements. Three members (R=Tb–Ho) have multiple phase transitions above 1.8 K. Eu appears to be divalent with total angular momentum L=0. Both EuCo2Ge2 and GdCo2Ge2 manifest essentially isotropic paramagnetic properties consistent with J=S=7/2. Clear magnetic anisotropy for rare-earth members with finite L was observed, with ErCo2Ge2 and TmCo2Ge2 manifesting planar anisotropy and the rest members manifesting axial anisotropy. The experimentally estimated crystal electric field (CEF) parameters B20 were calculated from the anisotropic paramagnetic θab and θc values and follow a trend that agrees well with theoretical predictions. The ordering temperatures, TN, as well as the polycrystalline averaged paramagnetic Curie–Weiss temperature, Θavg, for the heavy rare-earth members deviate from the de Gennes scaling, as the magnitude of both is the highest for Tb, which is sometimes seen for extremely axial systems. Except for SmCo2Ge2, metamagnetic transitions were observed at 1.8 K for all members that ordered antiferromagnetically. - Highlights: • Single crystalline RCo2Ge2 (R=Y, La–Nd, Sm–Tm) has been synthesized. • Anisotropies and antiferromagnetic ordering temperatures were determined down to 1.8 K. • Metamagnetic transitions for R=Pr, Nd, Eu

  19. Smoothing single-crystalline SiC surfaces by reactive ion etching using pure NF3 and NF3/Ar mixture gas plasmas

    International Nuclear Information System (INIS)

    In pure NF3 plasma, the etching rates of four kinds of single-crystalline SiC wafer etched at NF3 pressure of 2 Pa were the highest and it decreased with an increase in NF3 pressure. On the other hand, they increased with an increase in radio frequency (RF) power and were the highest at RF power of 200 W. A smooth surface was obtained on the single-crystalline 4H-SiC after reactive ion etching at NF3/Ar gas pressure of 2 Pa and addition of Ar to NF3 plasma increased the smoothness of SiC surface. Scanning electron microscopy observation revealed that the number of pillars decreased with an increase in the Ar-concentration in the NF3/Ar mixture gas. The roughness factor (Ra) values were decreased from 51.5 nm to 25.5 nm for the As-cut SiC, from 0.25 nm to 0.20 nm for the Epi-SiC, from 5.0 nm to 0.7 nm for the Si-face mirror-polished SiC, and from 0.20 nm to 0.16 nm for the C-face mirror-polished SiC by adding 60% Ar to the NF3 gas. Both the Ra values of the Epi- and the C-face mirror-polished wafer surfaces etched using the NF3/Ar (40:60) plasma were similar to that treated with mirror polishing, so-called the Catalyst-Referred Etching (CARE) method, with which the lowest roughness of surface was obtained among the chemical mirror polishing methods. Etching duration for smoothing the single-crystalline SiC surface using its treatment was one third of that with the CARE method

  20. Synthesis, structural and electronic properties of monodispersed self-organized single crystalline nanobricks of isocubanite CuFe2S3

    International Nuclear Information System (INIS)

    The nanoparticles with a pure cubic phase of isocubanite CuFe2S3 are successfully synthesized for the first time. The particles are self-organized into the single crystalline nanocomposites with a shape of “bricks” which are well ordered in a certain anisotropic orientation. All bricks have nearly the same shape and dimensions and may be considered as monodispersed nanobricks. Magnetic measurements show paramagnetic behavior of the compound down to 4.2 K with the antiferromagnetic correlation between iron ions. An average magnetic moment is about 2.8–3.0 μB per formula unit CuFe2S3. Mössbauer spectroscopy data reveal that the ferric ions in isocubanite are in the high-spin state (spin S=5/2) whereas the ferrous ions are in the intermediate-spin state (S=1). The Fe3+ and Fe2+ ions are distributed randomly over tetrahedral sites and the electron exchange between these ions is absent. This can explain nonmagnetic behavior of isocubanite. In the suggested method, the combined nanocomposites containing the magnetic chalcopyrite CuFeS2 and the nonmagnetic isocubanite CuFe2S3 can be synthesized in a certain sequence. Such composites could be useful for the applied nanotechnology. - Graphical abstract: Self-organized single crystalline “nanobricks” of isocubanite CuFe2S3 synthesized by a thermal pyrolysis method. - Highlights: • Self-organized single crystalline “nanobricks” of CuFe2S3 were synthesized. • All bricks are nearly monodispersed and well-ordered in a certain anisotropic orientation. • XRD, HRTEM, magnetic measurements and Mössbauer spectroscopy were used for characterization. • Nanobricks are paramagnetic down to 4.2 K with effective magnetic moment about 3.0 μB per f.u. • Mössbauer spectroscopy data indicate different spin states of Fe2+ and Fe3+ ions

  1. Temperature-Induced Metamagnetic Transition and Domain Structures of Single-Crystalline FeRh Thin Films on MgO(100)

    OpenAIRE

    Zhou, Xianzhong

    2013-01-01

    Exchange systems of FeRh with a hard magnetic layer are a promising approach for heat-assisted magnetic recording that can largely increase the storage density of hard disk drives. The FeRh alloy is known to undergo a temperature-induced metamagnetic transition from antiferromagnetic (AFM) to ferromagnetic (FM) just above the room temperature. But the AFM and FM phases coexist across the transition in single-crystalline FeRh thin lms with thin capping layers (e.g. Au, Al, or MgO). In order to...

  2. Temperature-Induced Metamagetic Transition and Domain Structure of Single-Crystalline FeRh Thin Films on MgO(100)

    OpenAIRE

    Zhou, Xianzhong

    2013-01-01

    Exchange systems of FeRh with a hard magnetic layer are a promising approach for heat-assisted magnetic recording that can largely increase the storage density of hard disk drives. The FeRh alloy is known to undergo a temperature-induced metamagnetic transition from antiferromagnetic (AFM) to ferromagnetic (FM) just above the room temperature. But the AFM and FM phases coexist across the tran- sition in single-crystalline FeRh thin films with thin capping layers (e.g. Au, Al, or MgO). In orde...

  3. Single crystalline YAG:Ce phosphor for powerful solid-state sources of white light. The influence of production conditions on luminescence properties and lighting characteristics

    Science.gov (United States)

    Nizhankovskyi, S. V.; Tan'ko, A. V.; Savvin, Yu. N.; Krivonogov, S. I.; Budnikov, A. T.; Voloshin, A. V.

    2016-06-01

    It is shown that the spectral properties and spatial distribution of LED radiation with a YAG:Ce single crystalline luminescent converter significantly depend on the morphology of the converter surface. The variation of surface roughness enables one to obtain a light source with a wide range of color characteristics. As a result of optimization of converter parameters we demonstrate a possibility of creating a white light LED with correlated color temperature TCC ~ 5000-6500 K and color rendering index CRI ≈ 60-70.

  4. Growth of atomically flat thin films of the electronically phase-separated manganite (La0.5Pr0.5)0.67Ca0.33MnO3

    International Nuclear Information System (INIS)

    Atomically flat and epitaxial thin films of the electronically phase-separated compound (La0.5Pr0.5)0.67Ca0.33MnO3 were grown on as-received and treated (110) NdGaO3 substrates by fine tuning of oxygen pressure during deposition. The optimal conditions were determined using surface morphology, transport, magnetization, and X-ray diffraction measurements. Optimal thin films show step flow growth mode and bulk-like physical properties compared to thin films grown in off-optimal oxygen pressures, viz. the highest maximum temperature coefficient of resistance, the highest peak resistivity temperature, and reduced coercive fields. (orig.)

  5. Synthesis and measurements of the optical bandgap of single crystalline complex metal oxide BaCuV2O7 nanowires by UV–VIS absorption

    International Nuclear Information System (INIS)

    Highlights: • Synthesis of single crystalline complex metal oxides BaCuV2O7 nanowires. • Surfactant free, economically favorable chemical solution deposition method. • Complex metal oxides nanowires with controlled stoichiometry. • Simply controlling the temperature and thickness of the coated film, we can easily obtain high quality BaCuV2O7 nanowires. - Abstract: The synthesis of single crystalline complex metal oxides BaCuV2O7 nanowires were attained by using surfactant free, economically favorable chemical solution deposition method. A thin layer of BaCuV2O7 nanocrystals is formed by the decomposition of complex metal oxide solution at 150 °C to provide nucleation sites for the growth of nanowires. The synthesized nanowires were typically 1–5 μm long with diameter from 50 to 150 nm. We showed that by simply controlling the temperature and thickness of the coated film, we can easily obtain high quality BaCuV2O7 nanowires. The UV–VIS absorption spectra show indirect bandgap of 2.65 ± 0.05 eV of nanowires. The temperature-dependent resistances of BaCuV2O7 nanowires agree with the exponential correlation, supporting that the conducting carriers are the quasi-free electrons. We believe that our methodology will provides a simple and convenient route for the synthesis of variety of complex metal oxides nanowires with controlled stoichiometry

  6. On the Mesoporogen-Free Synthesis of Single-Crystalline Hierarchically Structured ZSM-5 Zeolites in a Quasi-Solid-State System.

    Science.gov (United States)

    Ge, Tongguang; Hua, Zile; He, Xiaoyun; Lv, Jian; Chen, Hangrong; Zhang, Lingxia; Yao, Heliang; Liu, Ziwei; Lin, Chucheng; Shi, Jianlin

    2016-06-01

    Hierarchically structured zeolites (HSZs) have gained much academic and industrial interest owing to their multiscale pore structures and consequent excellent performances in varied chemical processes. Although a number of synthetic strategies have been developed in recent years, the scalable production of HSZs single crystals with penetrating and three-dimensionally (3-D) interconnected mesopore systems but without using a mesoscale template is still a great challenge. Herein, based on a steam-assisted crystallization (SAC) method, we report a facile and scalable strategy for the synthesis of single-crystalline ZSM-5 HSZs by using only a small amount of micropore-structure-directing agents (i.e., tetrapropylammonium hydroxide). The synthesized materials exhibited high crystallinity, a large specific surface area of 468 m(2)  g(-1) , and a pore volume of 0.43 cm(3)  g(-1) without sacrificing the microporosity (≈0.11 cm(3)  g(-1) ) in a product batch up to 11.7 g. Further, a kinetically controlled nucleation-growth mechanism is proposed for the successful synthesis of single-crystalline ZSM-5 HSZs with this novel process. As expected, compared with the conventional microporous ZSM-5 and amorphous mesoporous Al-MCM-41 counterparts, the synthesized HSZs exhibited significantly enhanced activity and stability and prolonged lifetime in model reactions, especially when bulky molecules were involved. PMID:27106662

  7. Observation of intrinsic Josephson effects in tetragonally synthesized single-crystalline NdBa2Cu3O6.65 films grown by tri-phase epitaxy

    Science.gov (United States)

    Yun, Kyung Sung; Hatano, Takeshi; Arisawa, Shunichi; Ishii, Akira; Wang, Huabing; Yamashita, Tsutomu; Iguchi, Ienari; Kawasaki, Masashi; Koinuma, Hideomi

    2008-07-01

    In this work twin-free tetragonal NdBa2Cu3O7-δ films were fabricated that exhibited superconductivity with sufficient anisotropy which produced intrinsic Josephson junction (IJJ) characteristics in the films. The intrinsic Josephson effects (IJEs) were observed in oxygen-deficient single-crystalline NdBa2Cu3O6.65 (NBCO) films grown on SrTiO3 (STO) substrates, using tri-phase epitaxy (TPE). The single-crystalline nature of NBCO films on well-matched STO substrates, and the precisely controlled oxygen content of the films, lead to the IJEs of the thin films. Furthermore, the films exhibit high anisotropy and clear multiple-branch structures, with hysteresis observed in the current-voltage characteristics. Periodic Josephson vortex-flow resistance oscillations were also observed for a magnetic field higher than 64 kOe, which was applied normal to the junctions. These results strongly support the single-crystal nature of TPE films, which play an important role in both the fundamental study and the practical applications of high-frequency devices.

  8. Characterization and photocatalytic activity of large-area single crystalline anatase TiO{sub 2} nanotube films hydrothermal synthesized on Plasma electrolytic oxidation seed layers

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Qiang [State Key Lab of Material Processing and Dies and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Cai, Qizhou, E-mail: caiqizhou@hust.edu.cn [State Key Lab of Material Processing and Dies and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Li, Xinwei [State Key Lab of Material Processing and Dies and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, Xidi [State Key Lab of Material Processing and Dies and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Institute of Functional Materials, Wuyi University, Jiangmen 529020 (China)

    2014-06-01

    Highlights: • Plasma electrolytic oxidation layer was used for synthesis of TiO{sub 2} nanotube film. • The prepared nanotube film was large-area single crystalline anatase. • The formation mechanism and properties of films were systematically investigated. - Abstract: The layer produced by Plasma electrolytic oxidation technique was used as seed layer for hydrothermal synthesis of large-area TiO{sub 2} nanotube film in this paper. The effects of hydrothermal parameters on the surface morphologies of films were investigated by field emission scanning electron microscopy (FSEM). The results showed that the surface morphologies of films can be easily changed by varying the NaOH concentration, reaction temperature and reaction time. In addition, the effect of calcination temperature on the morphologies, crystal structure, photophysical properties and photocatalytic activity of the nanotube films were also studied using field emission scanning electron microscopy (FSEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–Vis spectrophotometry and Fluorescence spectrophotometry. Calcination resulted in crystallization of the nanotubes from amorphous state to single-crystalline anatase phase. Furthermore, the increase of calcination temperature was beneficial to the improvement of crystallization degree. However, the nanotubes completely collapsed to form short nanorods when the calcination temperature increased to 700 °C. The TiO{sub 2} nanotube film calcined at 600 °C exhibited the narrowest band gap energy, the strongest UV light absorption, the weakest band–band PL intensity and the best photocatalytic activity.

  9. Synthesis, structural and electronic properties of monodispersed self-organized single crystalline nanobricks of isocubanite CuFe{sub 2}S{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Lyubutin, Igor S., E-mail: lyubutinig@mail.ru [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333 (Russian Federation); Lin, Chun-Rong, E-mail: crlin@mail.nptu.edu.tw [Department of Applied Physics, National Pingtung University, No.4-18 Minsheng Rd., Pingtung City, Pingtung 90003, Taiwan (China); Starchikov, Sergey S. [Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninsky av. 59, Moscow 119333 (Russian Federation); Siao, Yu-Jhan [Institute of Nanotechnology and Department of Mechanical Engineering, Southern Taiwan University, Tainan County 710, Taiwan (China); Tseng, Yaw-Teng [Department of Applied Physics, National Pingtung University, No.4-18 Minsheng Rd., Pingtung City, Pingtung 90003, Taiwan (China)

    2015-01-15

    The nanoparticles with a pure cubic phase of isocubanite CuFe{sub 2}S{sub 3} are successfully synthesized for the first time. The particles are self-organized into the single crystalline nanocomposites with a shape of “bricks” which are well ordered in a certain anisotropic orientation. All bricks have nearly the same shape and dimensions and may be considered as monodispersed nanobricks. Magnetic measurements show paramagnetic behavior of the compound down to 4.2 K with the antiferromagnetic correlation between iron ions. An average magnetic moment is about 2.8–3.0 μ{sub B} per formula unit CuFe{sub 2}S{sub 3}. Mössbauer spectroscopy data reveal that the ferric ions in isocubanite are in the high-spin state (spin S=5/2) whereas the ferrous ions are in the intermediate-spin state (S=1). The Fe{sup 3+} and Fe{sup 2+} ions are distributed randomly over tetrahedral sites and the electron exchange between these ions is absent. This can explain nonmagnetic behavior of isocubanite. In the suggested method, the combined nanocomposites containing the magnetic chalcopyrite CuFeS{sub 2} and the nonmagnetic isocubanite CuFe{sub 2}S{sub 3} can be synthesized in a certain sequence. Such composites could be useful for the applied nanotechnology. - Graphical abstract: Self-organized single crystalline “nanobricks” of isocubanite CuFe{sub 2}S{sub 3} synthesized by a thermal pyrolysis method. - Highlights: • Self-organized single crystalline “nanobricks” of CuFe{sub 2}S{sub 3} were synthesized. • All bricks are nearly monodispersed and well-ordered in a certain anisotropic orientation. • XRD, HRTEM, magnetic measurements and Mössbauer spectroscopy were used for characterization. • Nanobricks are paramagnetic down to 4.2 K with effective magnetic moment about 3.0 μ{sub B} per f.u. • Mössbauer spectroscopy data indicate different spin states of Fe{sup 2+} and Fe{sup 3+} ions.

  10. Smoothing single-crystalline SiC surfaces by reactive ion etching using pure NF{sub 3} and NF{sub 3}/Ar mixture gas plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Tasaka, Akimasa, E-mail: aki-tasaka-load@yahoo.co.jp [Department of Molecular Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, 1-3 Miyako-dani, Tatara, Kyotanabe, Kyoto 610-0321, Japan and Department of Applied Chemistry, Graduate School of Engineering, Doshisha University, 1-3 Miyako-dani, Tatara, Kyotanabe, Kyoto 610-0321 (Japan); Kotaka, Yuki [Department of Applied Chemistry, Graduate School of Engineering, Doshisha University, 1-3 Miyako-dani, Tatara, Kyotanabe, Kyoto 610-0321 (Japan); Oda, Atsushi; Saito, Morihiro [Department of Molecular Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, 1-3 Miyako-dani, Tatara, Kyotanabe, Kyoto 610-0321 (Japan); Tojo, Tetsuro [Toyo Tanso Co, Ltd., 5-7-2 Takeshima, Nishi yodogawa-ku, Osaka 555-0011 (Japan); Inaba, Minoru [Department of Molecular Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, 1-3 Miyako-dani, Tatara, Kyotanabe, Kyoto 610-0321, Japan and Department of Applied Chemistry, Graduate School of Science and Engineering, Doshisha University, 1-3 Miyako-dani, Tatara, Kyotanabe, Kyoto 610-0321 (Japan)

    2014-09-01

    In pure NF{sub 3} plasma, the etching rates of four kinds of single-crystalline SiC wafer etched at NF{sub 3} pressure of 2 Pa were the highest and it decreased with an increase in NF{sub 3} pressure. On the other hand, they increased with an increase in radio frequency (RF) power and were the highest at RF power of 200 W. A smooth surface was obtained on the single-crystalline 4H-SiC after reactive ion etching at NF{sub 3}/Ar gas pressure of 2 Pa and addition of Ar to NF{sub 3} plasma increased the smoothness of SiC surface. Scanning electron microscopy observation revealed that the number of pillars decreased with an increase in the Ar-concentration in the NF{sub 3}/Ar mixture gas. The roughness factor (R{sub a}) values were decreased from 51.5 nm to 25.5 nm for the As-cut SiC, from 0.25 nm to 0.20 nm for the Epi-SiC, from 5.0 nm to 0.7 nm for the Si-face mirror-polished SiC, and from 0.20 nm to 0.16 nm for the C-face mirror-polished SiC by adding 60% Ar to the NF{sub 3} gas. Both the R{sub a} values of the Epi- and the C-face mirror-polished wafer surfaces etched using the NF{sub 3}/Ar (40:60) plasma were similar to that treated with mirror polishing, so-called the Catalyst-Referred Etching (CARE) method, with which the lowest roughness of surface was obtained among the chemical mirror polishing methods. Etching duration for smoothing the single-crystalline SiC surface using its treatment was one third of that with the CARE method.

  11. Synthesis, structural and magnetic properties of self-organized single-crystalline nanobricks of chalcopyrite CuFeS2

    International Nuclear Information System (INIS)

    A thermal pyrolysis method has been developed to synthesize the tetragonal phase of chalcopyrite magnetic semiconductor CuFeS2 nanoparticles. All nanoparticles have the same anisotropic brick-like shape, and the “bricks” are self-organized in a certain orientation, creating well-ordered nanocomposites. High-resolution transmission electron microscopy and electron diffraction data show that every nanobrick is a single crystal with a layered atomic structure and characteristic dimensions of about 5 nm × 20 nm in plane. Magnetic measurements support the antiferromagnetic spin structure and reveal the appearance of a small ferromagnetic component below 60 K. Magnetic anomalies observed in the zero-field cooled magnetization curves at low temperatures may be related to an appearance of magnetic moment at the Cu ion site. The Mössbauer spectra show that only about 50% of Fe atoms are in the magnetically ordered α-phase of chalcopyrite. The remaining Fe is non-magnetic and may be located either in the γ-phase of chalcopyrite or in isocubanite

  12. Critical current densities amd pinning mechanisms of high-Tc films on single crystalline and technologically relevant substrates. Final report

    International Nuclear Information System (INIS)

    The report deals with six project tasks: (1) Effects of impurity additions at atomic level on the pinning behaviour and the critical current densities, examined in epitactic YBA2(Cu1-xNix)3O7 films. It could be proven that the Ni atoms increase the activation energy for flux movement and the critical current density in a concentration range of 02Sr2Can-1CunO2n+4+δ films (n = 2 and 3) with good crystalline properties, high critical currents, and high current densities were prepared. Thin YBa2Cu3O7 films of high quality could be grown on saphire substrates, both by the MO-CVD process and by MBE. The aim of depositing biaxially textured YBa2Cu3O7 films with high critical current densities on polycrystalline, metallic substrates was achieved by the IBAD process combined with MBE. The buffer layer was YSZ. Heterostructures of the layer sequence YBa2Cu3O7/CeO2/Y0.3Pr0.7Ba2Cu3O7/YBa2Cu3O7 and YBa2Cu3O7/CeO2/Au were prepared by laser ablation and sputtering processes, in order to examine Josephson ramp contacts and superconducting field-effect transistors. (orig./MM)

  13. Zero lattice mismatch and twin-free single crystalline ScN buffer layers for GaN growth on silicon

    International Nuclear Information System (INIS)

    We report the growth of thin ScN layers deposited by plasma-assisted molecular beam epitaxy on Sc2O3/Y2O3/Si(111) substrates. Using x-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we find that ScN films grown at 600 °C are single crystalline, twin-free with rock-salt crystal structure, and exhibit a direct optical band gap of 2.2 eV. A high degree of crystalline perfection and a very good lattice matching between ScN and GaN (misfit < 0.1%) makes the ScN/Sc2O3/Y2O3 buffer system a very promising template for the growth of high quality GaN layers on silicon

  14. One-step synthesis and near-infrared luminescent properties of Er3+ and Ni2+ doped single-crystalline Al18B4O33 nanorods

    International Nuclear Information System (INIS)

    Er3+ and Ni2+ doped single-crystalline Al18B4O33 nanorods were synthesized by a facile one-step toxic-free combustion method. The products were characterized by x-ray diffraction, transmission electron microscopy, selected area electron diffraction, and integrated and time-resolved photoluminescence (PL) measurements. The phase purity, morphology, and PL properties of Er3+ and Ni2+ doped Al18B4O33 nanorods can be readily controlled by tailoring the annealing temperature. The mechanism for the formation of Al18B4O33 nanorods with different aspect ratio is discussed. Er3+ doped Al18B4O33 nanorods show strong PL centered at 1531 nm, while Ni2+ doped products show superwide PL with a full width at half maximum of up to 250 nm. These aluminum borate nanostructures are promising building blocks for optoelectronics nanodevices.

  15. Single-crystalline CaMoO3 and SrMoO3 films grown by pulsed laser deposition in a reductive atmosphere

    International Nuclear Information System (INIS)

    Single-crystalline thin films of CaMoO3 and SrMoO3 with a Mo4+ state perovskite structure have been epitaxially grown by pulsed-laser deposition from Mo6+ state ceramic targets. Phase-pure films were obtained on nearly lattice-matched perovskite substrates using argon gas flow during the deposition. Transport properties of the films are consistent with those of paramagnetic and metallic phases, whereas the residual resistivities are far lower than those reported previously for films and bulk polycrystals. These results indicate that this growth method can be useful for exploring the interfaces and junction properties of 4d and 5d transition metal oxides that are unstable in a conventional oxidative atmosphere.

  16. Vortex dynamics in Bi2Sr2CaCu2O8+y single crystalline thin films with submicron structures

    International Nuclear Information System (INIS)

    To investigate vortex dynamics in Bi2Sr2CaCu2O8+y single crystalline thin films with regular holes array, we have already studied the vortex-flow resistance in various samples which have triangular, square, and randomly distributed holes arrays. A matching effect has been observed in the vortex-flow resistance in samples with the regular holes arrays. In addition to them, we measured the vortex-flow resistance, the critical current, and I-V characteristics in a sample with a regular surface structure of ∼30 nm depth. It is found that even that kind of the small surface structure induces the remarkable matching effect in the vortex liquid as well as the vortex solid

  17. Single crystalline Er{sub 2}O{sub 3}:sapphire films as potentially high-gain amplifiers at telecommunication wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, A. S.; Sadofev, S.; Schäfer, P.; Kalusniak, S.; Henneberger, F., E-mail: fh@physik.hu-berlin.de [Institut für Physik, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin (Germany)

    2014-11-10

    Single crystalline thin films of Er{sub 2}O{sub 3}, demonstrating efficient 1.5 μm luminescence of Er{sup 3+} at room temperature were grown on Al{sub 2}O{sub 3} substrate by molecular beam epitaxy. The absorption coefficient at 1.536 μm was found to reach 270 cm{sup −1} translating in a maximal possible gain of 1390 dBcm{sup −1}. In conjunction with the 10% higher refractive index as compared to Al{sub 2}O{sub 3}, this opens the possibility to use Er{sub 2}O{sub 3}:sapphire films as short-length waveguide amplifiers in telecommunication.

  18. Transformation of valence states and luminescence of chromium ions in the YAG:Cr, Mg and GGG:Cr, Mg single crystalline films

    Science.gov (United States)

    Zakharko, Ya. M.; Luchechko, A. P.; Syvorotka, I. M.; Syvorotka, I. I.; Ubizskii, S. B.; Melnyk, S. S.

    2005-01-01

    Peculiarities of absorption spectra and recombination luminescence of Y3Al5O12 (YAG) and Cd3Ga5O12 (GGG) single crystalline films co-doped with chromium and magnesium have been studied. The change of impurities concentration and annealing of samples in the reducing atmosphere have an influence on absorption in the visible and UV range. Using the results on absorption coefficient measurements in the band of 480 nm and in the absorption bands of Cr3+ ions, it was determined, that near 50% of the chromium ions located in octahedral sites are in the Cr4+ state in films with high chromium concentration. The investigation of thermostimulated luminescence confirms the existence of Cr2+ trap centres in the irradiated films caused by the magnesium dopant.

  19. Transformation of valence states and luminescence of chromium ions in the YAG:Cr, Mg and GGG:Cr, Mg single crystalline films

    International Nuclear Information System (INIS)

    Peculiarities of absorption spectra and recombination luminescence of Y3Al5O12 (YAG) and Cd3Ga5O12 (GGG) single crystalline films co-doped with chromium and magnesium have been studied. The change of impurities concentration and annealing of samples in the reducing atmosphere have an influence on absorption in the visible and UV range. Using the results on absorption coefficient measurements in the band of 480 nm and in the absorption bands of Cr3+ ions, it was determined, that near 50% of the chromium ions located in octahedral sites are in the Cr4+ state in films with high chromium concentration. The investigation of thermostimulated luminescence confirms the existence of Cr2+ trap centres in the irradiated films caused by the magnesium dopant. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Zero lattice mismatch and twin-free single crystalline ScN buffer layers for GaN growth on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Lupina, L.; Zoellner, M. H.; Dietrich, B.; Capellini, G. [IHP, Im Technologiepark 25, 15236 Frankfurt, Oder (Germany); Niermann, T.; Lehmann, M. [Technische Universität Berlin, Institut für Optik und Atomare Physik, Straße des 17. Juni 135, 10623 Berlin (Germany); Thapa, S. B.; Haeberlen, M.; Storck, P. [SILTRONIC AG, Hanns-Seidel-Platz 4, 81737 München (Germany); Schroeder, T. [IHP, Im Technologiepark 25, 15236 Frankfurt, Oder (Germany); BTU Cottbus, Konrad-Zuse-Str. 1, 03046 Cottbus (Germany)

    2015-11-16

    We report the growth of thin ScN layers deposited by plasma-assisted molecular beam epitaxy on Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) substrates. Using x-ray diffraction, Raman spectroscopy, and transmission electron microscopy, we find that ScN films grown at 600 °C are single crystalline, twin-free with rock-salt crystal structure, and exhibit a direct optical band gap of 2.2 eV. A high degree of crystalline perfection and a very good lattice matching between ScN and GaN (misfit < 0.1%) makes the ScN/Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} buffer system a very promising template for the growth of high quality GaN layers on silicon.

  1. Growth and luminescent properties of scintillators based on the single crystalline films of Lu3−xGdxAl5O12:Ce garnet

    International Nuclear Information System (INIS)

    Highlights: • Single crystalline films of Lu3−xGdxAl5O12 garnets at x = 0 ÷ 3.0 were grown by LPE method onto YAG substrates. • Lattice constant of Lu3−GdxAl5O12:Ce film and the misfit m between films and YAG substrate changed linearly with increasing of Gd content. • Effective Gd3+–Ce3+ energy transfer occurs in the Lu3−xGdxAl5O12:Ce films. • Best scintillation light yield is observed in the Lu3Al5O12:Ce and Lu2.4Gd0.6Al5O12:Ce films. • Increase of the Gd content in x = 1.5–2.5 range results in decreasing the scintillation LY of Lu3−xGdxAl5O12:Ce films. - Abstract: The work is related to the growth of scintillators based on the single crystalline films (SCF) of Ce3+ doped Lu3−GdxAl5O12 mixed rare-earth garnets by Liquid Phase Epitaxy (LPE) method. We have shown, that full set of Lu3−GdxAl5O12 SCFs with x values ranging from 0 to 3.0 can be successfully crystallized by the LPE method onto Y3Al5O12 (YAG) substrates from the melt-solutions based on PbO-B2O3 flux. The absorption, X-ray excited luminescence, photoluminescence, thermoluminescence and light yield measurements, the latter under excitation by α-particles of 239Pu and 241Am radioisotopes, were applied for their characterization

  2. Engineering the semiconductor/oxide interaction for stacking twin suppression in single crystalline epitaxial silicon(111)/insulator/Si(111) heterostructures

    International Nuclear Information System (INIS)

    The integration of alternative semiconductor layers on the Si material platform via oxide heterostructures is of interest to increase the performance and/or functionality of future Si-based integrated circuits. The single crystalline quality of epitaxial (epi) semiconductor-insulator-Si heterostructures is however limited by too high defect densities, mainly due to a lack of knowledge about the fundamental physics of the heteroepitaxy mechanisms at work. To shed light on the physics of stacking twin formation as one of the major defect mechanisms in (111)-oriented fcc-related heterostructures on Si(111), we report a detailed experimental and theoretical study on the structure and defect properties of epi-Si(111)/Y2O3/Pr2O3/Si(111) heterostructures. Synchrotron radiation-grazing incidence x-ray diffraction (SR-GIXRD) proves that the engineered Y2O3/Pr2O3 buffer dielectric heterostructure on Si(111) allows control of the stacking sequence of the overgrowing single crystalline epi-Si(111) layers. The epitaxy relationship of the epi-Si(111)/insulator/Si(111) heterostructure is characterized by a type A/B/A stacking configuration. Theoretical ab initio calculations show that this stacking sequence control of the heterostructure is mainly achieved by electrostatic interaction effects across the ionic oxide/covalent Si interface (IF). Transmission electron microscopy (TEM) studies detect only a small population of misaligned type B epi-Si(111) stacking twins whose location is limited to the oxide/epi-Si IF region. Engineering the oxide/semiconductor IF physics by using tailored oxide systems opens thus a promising approach to grow heterostructures with well-controlled properties.

  3. Initial step of hydride formation in single crystalline gadolinium thin films and islands studied on the nm-scale

    Energy Technology Data Exchange (ETDEWEB)

    Wanjelik, Sara, E-mail: Sara.Wanjelik@hhu.de [Institute of Applied Physics, Universitätsstrasse 1, 40225 Düsseldorf (Germany); Stolboushkina, Oxana [Institute of Applied Physics, Universitätsstrasse 1, 40225 Düsseldorf (Germany); Sibirian State University of Industry, Novokuznetsk 654007 (Russian Federation); Königshofen, Samuel; Getzlaff, Mathias [Institute of Applied Physics, Universitätsstrasse 1, 40225 Düsseldorf (Germany)

    2015-10-05

    Highlights: • Hydride formation in Gd films depends on hydrogen pressure and annealing conditions. • Chain formation of disclike islands (diameter about 4 nm) in 1 0 1 0 direction appears. • A triangular shaped structure is observed together with discs. • Transformation to hydride in islands starts from the edges. • All hydrogen induced structures can be removed stepwise by annealing up to 350 °C. - Abstract: The initial steps of hydrogen absorption in gadolinium systems are investigated by means of scanning tunneling microscopy (STM) under ultra high vacuum conditions. Gadolinium is grown on a W(1 1 0) substrate. Smooth films or islands can be obtained depending on the preparation conditions. Exposure to hydrogen leads to modifications of the Gd surface. Small discs with a diameter of a few nm and a height of one atomic step appear. The discs form chains with distinct directions. A triangular shaped structure is observed together with the discs. Areas that are completely transformed to GdH{sub 2} appear, too. The absorption process in islands was also investigated and compared to the behaviour of thin films. All measurements are performed at room temperature. By increasing the temperature, changes of the different modifications can be observed up to the point at which they vanish.

  4. Initial step of hydride formation in single crystalline gadolinium thin films and islands studied on the nm-scale

    International Nuclear Information System (INIS)

    Highlights: • Hydride formation in Gd films depends on hydrogen pressure and annealing conditions. • Chain formation of disclike islands (diameter about 4 nm) in 1 0 1 0 direction appears. • A triangular shaped structure is observed together with discs. • Transformation to hydride in islands starts from the edges. • All hydrogen induced structures can be removed stepwise by annealing up to 350 °C. - Abstract: The initial steps of hydrogen absorption in gadolinium systems are investigated by means of scanning tunneling microscopy (STM) under ultra high vacuum conditions. Gadolinium is grown on a W(1 1 0) substrate. Smooth films or islands can be obtained depending on the preparation conditions. Exposure to hydrogen leads to modifications of the Gd surface. Small discs with a diameter of a few nm and a height of one atomic step appear. The discs form chains with distinct directions. A triangular shaped structure is observed together with the discs. Areas that are completely transformed to GdH2 appear, too. The absorption process in islands was also investigated and compared to the behaviour of thin films. All measurements are performed at room temperature. By increasing the temperature, changes of the different modifications can be observed up to the point at which they vanish

  5. Growth of atomically flat thin films of the electronically phase-separated manganite (La{sub 0.5}Pr{sub 0.5}){sub 0.67}Ca{sub 0.33}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Jeen, Hyoungjeen [University of Florida, Department of Physics, Gainesville, FL (United States); Pusan National University, Department of Physics, Busan (Korea, Republic of); Javed, Rafiya; Biswas, Amlan [University of Florida, Department of Physics, Gainesville, FL (United States)

    2016-01-15

    Atomically flat and epitaxial thin films of the electronically phase-separated compound (La{sub 0.5}Pr{sub 0.5}){sub 0.67}Ca{sub 0.33}MnO{sub 3} were grown on as-received and treated (110) NdGaO{sub 3} substrates by fine tuning of oxygen pressure during deposition. The optimal conditions were determined using surface morphology, transport, magnetization, and X-ray diffraction measurements. Optimal thin films show step flow growth mode and bulk-like physical properties compared to thin films grown in off-optimal oxygen pressures, viz. the highest maximum temperature coefficient of resistance, the highest peak resistivity temperature, and reduced coercive fields. (orig.)

  6. New method of verificating optical flat flatness

    Science.gov (United States)

    Sun, Hao; Li, Xueyuan; Han, Sen; Zhu, Jianrong; Guo, Zhenglai; Fu, Yuegang

    2014-11-01

    Optical flat is commonly used in optical testing instruments, flatness is the most important parameter of forming errors. As measurement criteria, optical flat flatness (OFF) index needs to have good precision. Current measurement in China is heavily dependent on the artificial visual interpretation, through discrete points to characterize the flatness. The efficiency and accuracy of this method can not meet the demand of industrial development. In order to improve the testing efficiency and accuracy of measurement, it is necessary to develop an optical flat verification system, which can obtain all surface information rapidly and efficiently, at the same time, in accordance with current national metrological verification procedures. This paper reviews current optical flat verification method and solves the problems existing in previous test, by using new method and its supporting software. Final results show that the new system can improve verification efficiency and accuracy, by comparing with JJG 28-2000 metrological verification procedures method.

  7. One-pot high-yield synthesis of single-crystalline gold nanorods using glycerol as a low-cost and eco-friendly reducing agent

    Energy Technology Data Exchange (ETDEWEB)

    Parveen, Rashida [University of São Paulo, Institute of Chemistry of São Carlos (Brazil); Gomes, Janaina F. [Universidade Federal de São Carlos, Departamento de Engenharia Química (Brazil); Ullah, Sajjad [University of São Paulo, Institute of Chemistry of São Carlos (Brazil); Acuña, José J. S. [Universidade Federal do ABC, Centro de Ciências Naturais e Humanas (Brazil); Tremiliosi-Filho, Germano, E-mail: germano@iqsc.usp.br [University of São Paulo, Institute of Chemistry of São Carlos (Brazil)

    2015-10-15

    The formation of gold nanorods (AuNRs) has recently attracted great attention due to their shape-dependent optical properties that are important for many applications. The development of simpler and safer methods for the high-yield synthesis of AuNRs employing low-cost and easily handled reagents is thus of great importance. Here, we introduce, for the first time, a one-pot seedless method for the preparation of single-crystalline AuNRs in almost 100 % yield based on the use of glycerol in alkaline medium as an eco-friendly, low-cost and pH-tunable reducing agent. The synthesized AuNRs were characterized by UV–Vis–NIR spectroscopy, FEG–SEM and HRTEM. The effect of the presence of capping agent (CTAB) and the concentration of reactants (glycerol, NaOH and AgNO{sub 3}) on the yield and aspect ratio (AR) of AuNRs is discussed. The AR and yield of AuNRs showed a clear dependence on the pH and temperature of the reaction mixture as well as on the concentration of AgNO{sub 3} added as an auxiliary reagent. The longitudinal plasmon resonance band of the resulting AuNRs can be tuned between 620 and 1200 nm by varying the reaction conditions. AuNRs with an aspect ratio (AR) of around 4 were obtained in almost 100 % yield at room temperature and under mild reducing environment. The formation of AuNRs is faster at higher pH (>11) and higher temperature (>30 °C), but the AuNR yield is smaller (<70 %). Variation in the pH of the reaction mixture in the range 12–13.5 results in the formation of AuNRs with different ARs and in different yields (27–99 %). Detailed study of the AuNRs crystallography by HRTEM showed that the AuNRs grow in [001] direction and have a perfect single-crystalline fcc structure, free from structural faults or dislocations. The present green method, which introduces glycerol as a tunable reducing agent with a pH-dependent reducing power, can provide a more general strategy for the preparation of a wide range of metallic nanoparticles.

  8. Enhanced photoelectrochemical and photocatalytic performance of single-crystalline anatase TiO2 (1 0 1) nanobelts arrays originating from nanotubes arrays

    International Nuclear Information System (INIS)

    Graphical abstract: Single-crystalline anatase TiO2 (1 0 1) nanobelts arrays originating from nanotubes arrays were successfully prepared via simple anodization. This structure gives rise to faster electron mobility and less electron-trapping sites in the bulk, thereby effectively improving the separation efficiency of photogenerated charge carriers and photocatalytic activity. Thus, it can be utilized for solar energy conversion and environmental remediation. Highlights: ► Anatase TiO2 nanobelts arrays originating from nanotubes arrays were prepared. ► TiO2 nanobelts arrays exhibit higher PEC and PC properties. ► The performance enhanced mechanism was discussed in detail. ► It can be utilized for solar energy conversion and environmental remediation. - Abstract: TiO2 photocatalysts with high photocatalytic activity are potentially applied to degrade pollutants, split water and transform solar energy. Herein, TiO2 nanobelts (TiO2 NB) arrays originating from nanotubes arrays were successfully prepared via simple anodization. The surface morphology, structure, elemental composition, photoluminescence spectra (PL), photoelectrochemical (PEC) properties and photocatalytic activity of the resulting samples were investigated. The results show that as-prepared TiO2 NB arrays exhibited significant enhancement in separation efficiency of photogenerated electrons (e−) and holes (h+) pairs and then in photocatalytic activity under simulative solar irradiation compared with TiO2 nanotubes (TiO2 NT) arrays, which could be attributed to the following aspects: (i) specific belt-like morphology leads to higher accessibility of TiO2 NB arrays for reactants and more active sites on the surface of TiO2 NB; (ii) single-crystalline anatase phase structure gives rise to faster electron mobility and less electron-trapping sites in the bulk; and (iii) exposed crystal face (1 0 1) yields an enhanced reactivity with molecular O2, facilitating the trapping of photogenerated

  9. Luminescence and origin of lead-related centers in single crystalline films of Y.sub.2./sub.SiO.sub.5./sub. and Lu.sub.2./sub.SiO.sub.5./sub..

    Czech Academy of Sciences Publication Activity Database

    Babin, Vladimir; Gorbenko, V.; Krasnikov, A.; Mihóková, Eva; Nikl, Martin; Zazubovich, S.; Zorenko, Y.

    2013-01-01

    Roč. 56, Sept (2013), s. 124-128. ISSN 1350-4487 R&D Projects: GA ČR GAP204/12/0805; GA AV ČR IAA100100810 Institutional support: RVO:68378271 Keywords : luminescence * oxyorthosilicates * single crystalline films Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.140, year: 2013

  10. Influence of lead-related centers on luminescence of Ce.sup.3+./sup. and Pr.sup.3+./sup. centers in single crystalline films of aluminium perovskites and garnets

    Czech Academy of Sciences Publication Activity Database

    Babin, V.; Gorbenko, V.; Krasnikov, A.; Makhov, A.; Nikl, Martin; Zazubovich, S.; Zorenko, Y.

    2010-01-01

    Roč. 45, 3-6 (2010), 415-418. ISSN 1350-4487 R&D Projects: GA ČR GA202/08/0893 Institutional research plan: CEZ:AV0Z10100521 Keywords : aluminium perovskite s and garnets * single crystalline films Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.019, year: 2010

  11. Single crystalline SnO2 nanowires obtained from heat-treated SnO2 and C mixture and their electrochemical properties

    International Nuclear Information System (INIS)

    One-dimensional semiconductor nanostructures have demonstrated significant advantages for electrochemical electrode due to their remarkable size-dependent and structure-related properties. In this work, large-scale single-crystalline SnO2 nanowires have been successfully synthesized by thermal evaporation of a SnO2 and C powder under atmospheric conditions without any carrier gas or noble metal catalysts-coated substrate. The as-prepared samples exhibit uniform morphology with a thin diameter of 100–200 nm and length up to several tens of micrometers. The SnO2 nanowires directly grown on the initially deposition layer are found to grow along [301] direction, which is possibly dominated by a vapor–solid (VS) mechanism. The SnO2 nanowires synthesized by this simple and cheap method deliver a very high lithium storage capacity with good cycle stability and high rate capability, allowing for the achievement of high energy density and long cycle life for the next-generation energy conversion and storage devices. - Highlights: • Large-scale SnO2 nanowires were prepared by thermal evaporation without any carrier gas or noble metal catalysts. • A growth model based on vapor–solid (VS) mechanism is constructed for the formation of the 1D nanostructure. • SnO2 nanowires delivered high lithium storage capacity with good cycle stability and high rate capability

  12. One-step synthesis route of the aligned and non-aligned single crystalline α-Si3N4 nanowires

    Institute of Scientific and Technical Information of China (English)

    Mashkoor AHMAD; ZHAO Jiong; ZHANG Fan; PAN CaoFeng; ZHU Jing

    2009-01-01

    This paper reports the bulk synthesis route of the aligned and non-aligned high-quality α-Si3N4 nanowires (NWS) which were grown directly from the Si substrate by vapor phase deposition at 1050℃. The as-grown products were characterized by employing XRD, SEM, HRTEM and photoluminescence. The microscopic results revealed that the products consist of single crystalline aligned and non-aligned α-Si3N4 NWs having a same diameter range of 30-100 nm and different lengths of about hun-dreds of microns. The XRD observation revealed that the products consist of co-phase Si3N4 NWs. The room temperature PL spectra indicated that the NWs have good emission property. The non-aligned NWs were formed at lower temperature as compared with aligned NWs. Our method is a simple and one-step procedure to synthesize the bulk-quantity and high-purity aligned and non-aligned α-Si3N4NWs at s relatively low temperature. The possible growth mechanism was also briefly discussed.

  13. Highly Ordered Single Crystalline Nanowire Array Assembled Three-Dimensional Nb3O7(OH) and Nb2O5 Superstructures for Energy Storage and Conversion Applications.

    Science.gov (United States)

    Zhang, Haimin; Wang, Yun; Liu, Porun; Chou, Shu Lei; Wang, Jia Zhao; Liu, Hongwei; Wang, Guozhong; Zhao, Huijun

    2016-01-26

    Three-dimensional (3D) metal oxide superstructures have demonstrated great potentials for structure-dependent energy storage and conversion applications. Here, we reported a facile hydrothermal method for direct growth of highly ordered single crystalline nanowire array assembled 3D orthorhombic Nb3O7(OH) superstructures and their subsequent thermal transformation into monoclinic Nb2O5 with well preserved 3D nanowire superstructures. The performance of resultant 3D Nb3O7(OH) and Nb2O5 superstructures differed remarkably when used for energy conversion and storage applications. The thermally converted Nb2O5 superstructures as anode material of lithium-ion batteries (LiBs) showed higher capacity and excellent cycling stability compared to the Nb3O7(OH) superstructures, while directly hydrothermal grown Nb3O7(OH) nanowire superstructure film on FTO substrate as photoanode of dye-sensitized solar cells (DSSCs) without the need for further calcination exhibited an overall light conversion efficiency of 6.38%, higher than that (5.87%) of DSSCs made from the thermally converted Nb2O5 film. The high energy application performance of the niobium-based nanowire superstructures with different chemical compositions can be attributed to their large surface area, superior electron transport property, and high light utilization efficiency resulting from a 3D superstructure, high crystallinity, and large sizes. The formation process of 3D nanowire superstructures before and after thermal treatment was investigated and discussed based on our theoretical and experimental results. PMID:26579783

  14. Three-Dimensional Cu Foam-Supported Single Crystalline Mesoporous Cu2O Nanothorn Arrays for Ultra-Highly Sensitive and Efficient Nonenzymatic Detection of Glucose.

    Science.gov (United States)

    Dong, Chaoqun; Zhong, Hua; Kou, Tianyi; Frenzel, Jan; Eggeler, Gunther; Zhang, Zhonghua

    2015-09-16

    Highly sensitive and efficient biosensors play a crucial role in clinical, environmental, industrial, and agricultural applications, and tremendous efforts have been dedicated to advanced electrode materials with superior electrochemical activities and low cost. Here, we report a three-dimensional binder-free Cu foam-supported Cu2O nanothorn array electrode developed via facile electrochemistry. The nanothorns growing in situ along the specific direction of have single crystalline features and a mesoporous surface. When being used as a potential biosensor for nonenzyme glucose detection, the hybrid electrode exhibits multistage linear detection ranges with ultrahigh sensitivities (maximum of 97.9 mA mM(-1) cm(-2)) and an ultralow detection limit of 5 nM. Furthermore, the electrode presents outstanding selectivity and stability toward glucose detection. The distinguished performances endow this novel electrode with powerful reliability for analyzing human serum samples. These unprecedented sensing characteristics could be ascribed to the synergistic action of superior electrochemical catalytic activity of nanothorn arrays with dramatically enhanced surface area and intimate contact between the active material (Cu2O) and current collector (Cu foam), concurrently supplying good conductivity for electron/ion transport during glucose biosensing. Significantly, our findings could guide the fabrication of new metal oxide nanostructures with well-organized morphologies and unique properties as well as low materials cost. PMID:26305112

  15. Front Side Metallization of n- and p-Type, High-Efficiency, Single-Crystalline Si Solar Cells: Assessing the Temperature-Dependent Series Resistance

    Science.gov (United States)

    Willsch, Benjamin; Kumar, Praveen; Eibl, Oliver

    2016-06-01

    The series resistance of high-quality, single crystalline p-type and n-type solar cells was measured in a temperature range between 80 K and room temperature. Among one cell type ( n or p), cells were processed identically. Only the processing of the front side metallization was varied by using different processing conditions and screen printing pastes. High-efficiency n- ( η = 20.0%) and p-type ( η = 18.0%) cells yielded similar contact and series resistance and common features of the microstructure of the front side contact, i.e. a glass layer containing Ag colloids with typical diameters of 5-200 nm. Temperature-dependent current voltage curves ( I- V curves) were acquired and evaluated with respect to the series resistance by using two different methods yielding different results. On average the series resistance follows the trends of the contact resistance of the front side metallization determined at room temperature. Optimally processed cells yielded series resistances of less than 25 mΩ cm2 (method #1) both for n- and p-type cells. It could be shown that the series resistance reflected the processing conditions and paste properties and yielded similar temperature dependence for p- and n-type cells with small contact resistance. Therefore, the relevant current paths of high-efficiency n- and p-type cells appear to be similar in the front side metallization and include the glass layer which contains a high density of Ag colloids.

  16. Fabrication of GaN epitaxial thin film on InGaZnO{sub 4} single-crystalline buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Shinozaki, Tomomasa, E-mail: shinozaki@lucid.msl.titech.ac.j [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); Nomura, Kenji [ERATO-SORST, Japan Science and Technology Agency (JST), in Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); Katase, Takayoshi [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); Kamiya, Toshio [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); ERATO-SORST, Japan Science and Technology Agency (JST), in Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); Hirano, Masahiro [ERATO-SORST, Japan Science and Technology Agency (JST), in Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); Hosono, Hideo [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); ERATO-SORST, Japan Science and Technology Agency (JST), in Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan); Frontier Research Center, Tokyo Institute of Technology, 4259 Nagatuta, Midori-ku, Yokohama (Japan)

    2010-03-31

    Epitaxial (0001) films of GaN were grown on (111) YSZ substrates using single-crystalline InGaZnO{sub 4} (sc-IGZO) lattice-matched buffer layers by molecular beam epitaxy with a NH{sub 3} source. The epitaxial relationships are (0001){sub GaN}//(0001){sub IGZO}//(111){sub YSZ} in out-of-plane and [112-bar 0]{sub GaN}//[112-bar 0]{sub IGZO}//[11-bar 0]{sub YSZ} in in-plane. This is different from those reported for GaN on many oxide crystals; the in-plane orientation of GaN crystal lattice is rotated by 30{sup o} with respect to those of oxide substrates except for ZnO. Although these GaN films showed relatively large tilting and twisting angles, which would be due to the reaction between GaN and IGZO, the GaN films grown on the sc-IGZO buffer layers exhibited stronger band-edge photoluminescence than GaN grown on a low-temperature GaN buffer layer.

  17. Transformation of valence states and luminescence of chromium ions in the YAG:Cr, Mg and GGG:Cr, Mg single crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Zakharko, Ya.M.; Luchechko, A.P. [Faculty of Electronics, Ivan Franko National University of Lviv, 107 Tarnavskogo St., Lviv 79017 (Ukraine); Syvorotka, I.M.; Syvorotka, I.I.; Melnyk, S.S. [Institute for Materials SRC ' ' Carat' ' , 202 Stryjska St., Lviv 79031 (Ukraine); Ubizskii, S.B. [Institute for Materials SRC ' ' Carat' ' , 202 Stryjska St., Lviv 79031 (Ukraine); Institute for Telecommunication, Radioelectronics and Electronic Engineering, Lviv Polytechnic National University, 12 Bandera St., Lviv 79013 (Ukraine)

    2005-01-01

    Peculiarities of absorption spectra and recombination luminescence of Y{sub 3}Al{sub 5}O{sub 12} (YAG) and Cd{sub 3}Ga{sub 5}O{sub 12} (GGG) single crystalline films co-doped with chromium and magnesium have been studied. The change of impurities concentration and annealing of samples in the reducing atmosphere have an influence on absorption in the visible and UV range. Using the results on absorption coefficient measurements in the band of 480 nm and in the absorption bands of Cr{sup 3+} ions, it was determined, that near 50% of the chromium ions located in octahedral sites are in the Cr{sup 4+} state in films with high chromium concentration. The investigation of thermostimulated luminescence confirms the existence of Cr{sup 2+} trap centres in the irradiated films caused by the magnesium dopant. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. Front Side Metallization of n- and p-Type, High-Efficiency, Single-Crystalline Si Solar Cells: Assessing the Temperature-Dependent Series Resistance

    Science.gov (United States)

    Willsch, Benjamin; Kumar, Praveen; Eibl, Oliver

    2016-03-01

    The series resistance of high-quality, single crystalline p-type and n-type solar cells was measured in a temperature range between 80 K and room temperature. Among one cell type (n or p), cells were processed identically. Only the processing of the front side metallization was varied by using different processing conditions and screen printing pastes. High-efficiency n- (η = 20.0%) and p-type (η = 18.0%) cells yielded similar contact and series resistance and common features of the microstructure of the front side contact, i.e. a glass layer containing Ag colloids with typical diameters of 5-200 nm. Temperature-dependent current voltage curves (I-V curves) were acquired and evaluated with respect to the series resistance by using two different methods yielding different results. On average the series resistance follows the trends of the contact resistance of the front side metallization determined at room temperature. Optimally processed cells yielded series resistances of less than 25 mΩ cm2 (method #1) both for n- and p-type cells. It could be shown that the series resistance reflected the processing conditions and paste properties and yielded similar temperature dependence for p- and n-type cells with small contact resistance. Therefore, the relevant current paths of high-efficiency n- and p-type cells appear to be similar in the front side metallization and include the glass layer which contains a high density of Ag colloids.

  19. The crystal structure and luminescence quenching of poly- and single-crystalline KYW{sub 2}O{sub 8}:Tb{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Schwung, Sebastian [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Rytz, Daniel, E-mail: rytz@fee-io.de [Forschungsinstitut für mineralische und metallische Werkstoffe-Edelsteine/ Edelmetalle-GmbH (FEE), Struthstraße 2, 55743 Idar-Oberstein (Germany); Heying, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30 48149 Münster (Germany); Enseling, David [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Jüstel, Thomas, E-mail: tj@fh-muenster.de [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Pöttgen, Rainer, E-mail: pottgen@uni-muenster.de [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30 48149 Münster (Germany)

    2015-10-15

    Terbium-substituted KYW{sub 2}O{sub 8} single crystals of high optical quality were grown by the top seeded solution growth technique. The degree of yttrium–terbium mixed occupancy was determined for two samples through structure refinements on the basis of single crystal X-ray diffractometer data. Temperature dependent magnetic susceptibility data underline the paramagnetic nature of terbium doped crystals. No magnetic ordering is evident down to 2 K. Luminescence measurements yield the typical excitation and emission spectra as expected for Tb{sup 3+} activated materials. The decay time of Tb{sup 3+} decreases linearly with the Tb{sup 3+} concentration, while the excess of thermal quenching does not change significantly. At about 405 K the decay time is reduced by roughly 50% relative to the low-temperature value, both for the powders as for the single crystals. - Highlights: • Single crystalline and powder series of K(Y,Tb)W{sub 2}O{sub 8.} • Refined XRD data of high quality crystals. • Linear decrease of the decay time with Tb{sup 3+} content.

  20. One-pot synthesis of CoNiO{sub 2} single-crystalline nanoparticles as high-performance electrode materials of asymmetric supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Du, Weimin, E-mail: dwmchem@163.com; Gao, Yanping; Tian, Qingqing; Li, Dan; Zhang, Zhenhu; Guo, Jiaojiao [Anyang Normal University, College of Chemistry and Chemical Engineering (China); Qian, Xuefeng [Shanghai Jiao Tong University, School of Chemistry and Chemical Technology (China)

    2015-09-15

    A facile one-pot solvothermal method has been developed to synthesize CoNiO{sub 2} single-crystalline nanoparticles. Crystal phase, morphology, crystal lattice, and composition of the obtained products were characterized by X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis, respectively. Results revealed that the as-synthesized CoNiO{sub 2} nanoparticles belong to cubic structure with narrow size-distribution (8–10 nm). Subsequently, new asymmetric supercapacitors were successfully assembled with CoNiO{sub 2} nanoparticles as positive electrode and activated carbon as negative electrode. The electrochemical results show that asymmetric supercapacitors based on CoNiO{sub 2} nanoparticles possess excellent supercapacitor properties, i.e., a stable electrochemical window of 0–1.7 V, higher energy density of 24.0 Wh/kg at a power density of 415.4 W/kg, and excellent cycling stability (96.8 % capacitance retention after 5000 charge–discharge cycles). Meanwhile, both a light-emitting diode and a mini fan can be powered by two series connection asymmetric supercapacitors. These results imply that the present asymmetric supercapacitors based on CoNiO{sub 2} nanoparticles possess the promising potential application in the field of high-performance energy storage.

  1. One-pot synthesis of CoNiO2 single-crystalline nanoparticles as high-performance electrode materials of asymmetric supercapacitors

    International Nuclear Information System (INIS)

    A facile one-pot solvothermal method has been developed to synthesize CoNiO2 single-crystalline nanoparticles. Crystal phase, morphology, crystal lattice, and composition of the obtained products were characterized by X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis, respectively. Results revealed that the as-synthesized CoNiO2 nanoparticles belong to cubic structure with narrow size-distribution (8–10 nm). Subsequently, new asymmetric supercapacitors were successfully assembled with CoNiO2 nanoparticles as positive electrode and activated carbon as negative electrode. The electrochemical results show that asymmetric supercapacitors based on CoNiO2 nanoparticles possess excellent supercapacitor properties, i.e., a stable electrochemical window of 0–1.7 V, higher energy density of 24.0 Wh/kg at a power density of 415.4 W/kg, and excellent cycling stability (96.8 % capacitance retention after 5000 charge–discharge cycles). Meanwhile, both a light-emitting diode and a mini fan can be powered by two series connection asymmetric supercapacitors. These results imply that the present asymmetric supercapacitors based on CoNiO2 nanoparticles possess the promising potential application in the field of high-performance energy storage.

  2. Magnetotransport of single crystalline YSb

    Science.gov (United States)

    Ghimire, N. J.; Botana, A. S.; Phelan, D.; Zheng, H.; Mitchell, J. F.

    2016-06-01

    We report magnetic field dependent transport measurements on a single crystal of cubic YSb together with first principles calculations of its electronic structure. The transverse magnetoresistance does not saturate up to 9 T and attains a value of 75 000% at 1.8 K. The Hall coefficient is electron-like at high temperature, changes sign to hole-like between 110 and 50 K, and again becomes electron-like below 50 K. First principles calculations show that YSb is a compensated semimetal with a qualitatively similar electronic structure to that of isostructural LaSb and LaBi, but with larger Fermi surface volume. The measured electron carrier density and Hall mobility calculated at 1.8 K, based on a single band approximation, are 6.5× {{10}20} cm‑3 and 6.2× {{10}4} cm2 Vs‑1, respectively. These values are comparable with those reported for LaBi and LaSb. Like LaBi and LaSb, YSb undergoes a magnetic field-induced metal-insulator-like transition below a characteristic temperature T m, with resistivity saturation below 13 K. Thickness dependent electrical resistance measurements show a deviation of the resistance behavior from that expected for a normal metal; however, they do not unambiguously establish surface conduction as the mechanism for the resistivity plateau.

  3. Graphene Oxide-Assisted Synthesis of Microsized Ultrathin Single-Crystalline Anatase TiO2 Nanosheets and Their Application in Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Chen, Biao; Sha, Junwei; Li, Wei; He, Fang; Liu, Enzuo; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Zhao, Naiqin

    2016-02-01

    High-quality microsized ultrathin single-crystalline anatase TiO2 nanosheets (MS-TiO2) with exposed {001} facets were synthesized by a facile and low-cost two-step process that combines a graphene oxide (GO)-assisted hydrothermal method with calcination. Both GO and HF play an important role in the formation of well dispersed MS-TiO2. As a novel microsized (1-4 μm) ultrathin two-dimensional (2D) material, MS-TiO2 possesses much higher lateral size and aspect ratio compared to common 2D nanosized (30-60 nm) ultrathin TiO2 nanosheets (NS-TiO2), resulting in excellent electronic conductivity and superior electron transfer and diffusion properties. Here, we fabricated MS-TiO2 and NS-TiO2, both of which were incorporated with the TiO2 nanoparticles (P25) to constitute the hybrid photoanode of dye-sensitized solar cells (DSSCs), and explored the effect of the lateral size (nano- and micro-) of ultrathin TiO2 nanosheets on their electron transfer and diffusion properties. Benefiting from the faster electron transfer rate and short diffusion path of the MS-TiO2, the MS-TiO2/P25 gains the more superior performance compared to pure P25 and NS-TiO2/P25 in the application of DSSCs. Moreover, it is expected that the novel high aspect ratio MS-TiO2 may be applied in diverse fields including photocatalysis, photodetectors, lithium-ion batteries and others concerning the environment and energy. PMID:26745514

  4. Unusually high critical current of clean P-doped BaFe{sub 2}As{sub 2} single crystalline thin film

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, F., E-mail: fritz.kurth@ifw-dresden.de; Engelmann, J.; Schultz, L. [Institute for Metallic Materials, IFW Dresden, 01171 Dresden (Germany); TU Dresden, 01062 Dresden (Germany); Tarantini, C.; Jaroszynski, J. [Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, 2031 East Paul Dirac Drive, Tallahassee, Florida 32310 (United States); Grinenko, V.; Reich, E.; Hühne, R. [Institute for Metallic Materials, IFW Dresden, 01171 Dresden (Germany); Hänisch, J. [Institute for Metallic Materials, IFW Dresden, 01171 Dresden (Germany); Karlsruhe Institute of Technology, Institute for Technical Physics, Hermann von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Mori, Y.; Sakagami, A.; Kawaguchi, T.; Ikuta, H. [Department of Crystalline Materials Science, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Holzapfel, B. [Karlsruhe Institute of Technology, Institute for Technical Physics, Hermann von Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Iida, K., E-mail: iida@nuap.nagoya-u.ac.jp [Institute for Metallic Materials, IFW Dresden, 01171 Dresden (Germany); Department of Crystalline Materials Science, Nagoya University, Chikusa, Nagoya 464-8603 (Japan)

    2015-02-16

    Microstructurally clean, isovalently P-doped BaFe{sub 2}As{sub 2} (Ba-122) single crystalline thin films have been prepared on MgO (001) substrates by molecular beam epitaxy. These films show a superconducting transition temperature (T{sub c}) of over 30 K although P content is around 0.22, which is lower than the optimal one for single crystals (i.e., 0.33). The enhanced T{sub c} at this doping level is attributed to the in-plane tensile strain. The strained film shows high transport self-field critical current densities (J{sub c}) of over 6 MA/cm{sup 2} at 4.2 K, which are among the highest for Fe based superconductors (FeSCs). In-field J{sub c} exceeds 0.1 MA/cm{sup 2} at μ{sub 0}H=35 T for H‖ab and μ{sub 0}H=18 T for H‖c at 4.2 K, respectively, in spite of moderate upper critical fields compared to other FeSCs with similar T{sub c}. Structural investigations reveal no defects or misoriented grains pointing to strong pinning centers. We relate this unexpected high J{sub c} to a strong enhancement of the vortex core energy at optimal T{sub c}, driven by in-plane strain and doping. These unusually high J{sub c} make P-doped Ba-122 very favorable for high-field magnet applications.

  5. On-Demand Guided Bone Regeneration with Microbial Protection of Ornamented SPU Scaffold with Bismuth-Doped Single Crystalline Hydroxyapatite: Augmentation and Cartilage Formation.

    Science.gov (United States)

    Selvakumar, M; Srivastava, Priyanka; Pawar, Harpreet Singh; Francis, Nimmy K; Das, Bodhisatwa; Sathishkumar, G; Subramanian, Bhuvaneshwaran; Jaganathan, Saravana Kumar; George, Gibin; Anandhan, S; Dhara, Santanu; Nando, Golok B; Chattopadhyay, Santanu

    2016-02-17

    Guided bone regeneration (GBR) scaffolds are futile in many clinical applications due to infection problems. In this work, we fabricated GBR with an anti-infective scaffold by ornamenting 2D single crystalline bismuth-doped nanohydroxyapatite (Bi-nHA) rods onto segmented polyurethane (SPU). Bi-nHA with high aspect ratio was prepared without any templates. Subsequently, it was introduced into an unprecedented synthesized SPU matrix based on dual soft segments (PCL-b-PDMS) of poly(ε-caprolactone) (PCL) and poly(dimethylsiloxane) (PDMS), by an in situ technique followed by electrospinning to fabricate scaffolds. For comparison, undoped pristine nHA rods were also ornamented into it. The enzymatic ring-opening polymerization technique was adapted to synthesize soft segments of PCL-b-PDMS copolymers of SPU. Structure elucidation of the synthesized polymers is done by nuclear magnetic resonance spectroscopy. Sparingly, Bi-nHA ornamented scaffolds exhibit tremendous improvement (155%) in the mechanical properties with excellent antimicrobial activity against various human pathogens. After confirmation of high osteoconductivity, improved biodegradation, and excellent biocompatibility against osteoblast cells (in vitro), the scaffolds were implanted in rabbits by subcutaneous and intraosseous (tibial) sites. Various histological sections reveal the signatures of early cartilage formation, endochondral ossification, and rapid bone healing at 4 weeks of the critical defects filled with ornamented scaffold compared to SPU scaffold. This implies osteogenic potential and ability to provide an adequate biomimetic microenvironment for mineralization for GBR of the scaffolds. Organ toxicity studies further confirm that no tissue architecture abnormalities were observed in hepatic, cardiac, and renal tissue sections. This finding manifests the feasibility of fabricating a mechanically adequate nanofibrous SPU scaffold by a biomimetic strategy and the advantages of Bi

  6. Flat for Free Flow

    Institute of Scientific and Technical Information of China (English)

    Yan Manman

    2010-01-01

    @@ Just as Thomas Fried man's famous book,The World Is Flat,if not completely flat,it is anyway tending to be shaped flat.January 1,2010 saw the formation of the China-ASEAN Free Trade Agreement(CAFTA),which was another historical event flattening majority of Asia continent for international trade.

  7. MAMA NUV Flats

    Science.gov (United States)

    Sana, Hugues

    2013-10-01

    This program is aimed at obtaining NUV-MAMA flat-field observations for the construction of pixel-to-pixel flats {p-flats} with a SNR of 100 per binned pixel. The flats are obtained with the DEUTERIUM-lamp and the MR grisms G230M. The actual choice of central wavelength and slit combination depends on the observed count level within each exposure.Note that STIS NUV-MAMA flats are taken every other cycles{i.e. during odd number cycles} in order to not drain the DEUTERIUMlamp lifetime.

  8. Growth and luminescent properties of Lu.sub.2./sub.SiO.sub.5./sub. and Lu.sub.2./sub.SiO.sub.5./sub.:Ce single crystalline films

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Nikl, Martin; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Kučerková, Romana; Sidletskiy, O.; Grynyov, B.; Fedorov, A.

    2011-01-01

    Roč. 33, č. 6 (2011), s. 846-852. ISSN 0925-3467 R&D Projects: GA ČR GA202/08/0893 Institutional research plan: CEZ:AV0Z10100521 Keywords : luminescence * Lu 2 SiO 5 :Ce * single crystalline fil * liquid phase epitaxy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.023, year: 2011

  9. Strongly Gorenstein Flat Dimensions

    Institute of Scientific and Technical Information of China (English)

    Chun Xia ZHANG; Li Min WANG

    2011-01-01

    This article is concerned with the strongly Gorenstein flat dimensions of modules and rings.We show this dimension has nice properties when the ring is coherent,and extend the well-known Hilbert's syzygy theorem to the strongly Gorenstein flat dimensions of rings.Also,we investigate the strongly Gorenstein flat dimensions of direct products of rings and (almost)excellent extensions of rings.

  10. Creating flat design websites

    CERN Document Server

    Pratas, Antonio

    2014-01-01

    This book contains practical, step-by-step tutorials along with plenty of explanation about designing your flat website. Each section is introduced sequentially, building up your web design skills and completing your website.Creating Flat Design Websites is ideal for you if you are starting on your web development journey, but this book will also benefit seasoned developers wanting to start developing in flat.

  11. MAMA FUV Flats

    Science.gov (United States)

    Mason, Elena

    2012-10-01

    This program aims at obtaining FUV-MAMA flat-field observations to create a new p-flats with a SNR of 100 per {low resolution} pixel. The flats are obtained with the Krypton-lamp and the MR grating G140M, similarly to the cycle 17 and 18 programs. However the exact instrument setup {slit width and central wavelength} might change depending on the desired count level {which will be close to the internally allowed global rate limit}.

  12. Flat Pack Toy Design

    Science.gov (United States)

    Hutcheson, Brian

    2007-01-01

    In this article, the author introduces the concept of flat pack toys. Flat pack toys are designed using a template on a single sheet of letter-sized card stock paper. Before being cut out and built into a three-dimensional toy, they are scanned into the computer and uploaded to a website. With the template accessible from the website, anyone with…

  13. Flat Band Quastiperiodic Lattices

    Science.gov (United States)

    Bodyfelt, Joshua; Flach, Sergej; Danieli, Carlo

    2014-03-01

    Translationally invariant lattices with flat bands (FB) in their band structure possess irreducible compact localized flat band states, which can be understood through local rotation to a Fano structure. We present extension of these quasi-1D FB structures under incommensurate lattices, reporting on the FB effects to the Metal-Insulator Transition.

  14. Growth and luminescent properties of Lu.sub.2./sub.SiO.sub.5./sub. and Lu.sub.2./sub.SiO.sub.5./sub.:Ce single crystalline films

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Nikl, Martin; Gorbenko, V.; Mareš, Jiří A.; Savchyn, V.; Voznyak, T.; Solsky, I.; Grynyov, B.; Sidletskiy, O.; Kurtsev, D.; Beitlerová, Alena; Kučerková, Romana

    Bristol : IOP Publishing, 2010, 012010/1-012010/12. ISSN 1757-8981. - (IOP Conference Series: Materials Science and Engineering. vol. 15). [Europhysical Conference on Defects in Insulating Materials /11./ (EURODIM 2010). Pecs (HU), 12.07.2010-16.07.2010] R&D Projects: GA ČR GA202/08/0893 Institutional research plan: CEZ:AV0Z10100521 Keywords : luminescent properties * single crystalline films (SCF) * Lu 2 SiO 5 (LSO) * Ce-doped Subject RIV: BM - Solid Matter Physics ; Magnetism http://dx.doi.org/10.1088/1757-899X/15/1/012010

  15. X-ray-photoemission-spectroscopy evidence for anomalous oxidation states of silicon after exposure of hydrogen-terminated single-crystalline (100) silicon to a diluted N2:N2O atmosphere

    International Nuclear Information System (INIS)

    The early oxidation stages of hydrogen-terminated single-crystalline (100) silicon exposed to a diluted N2 : N2O atmosphere at 8500C for different durations have been studied by x-ray photoemission spectroscopy, following the evolution of the Si 2p signal. Evidence is given that the usual analysis, in terms of five pairs of peaks attributed to silicon in the oxidation states from 0 to +4, does not account for the observed Si 2p signal. An explanation for silicon in unusual oxidation states is proposed. (author)

  16. Individual energy savings for individual flats in blocks of flats

    DEFF Research Database (Denmark)

    Nielsen, Anker; Rose, Jørgen

    2014-01-01

    is distributed on the individual flats. Today, most blocks of flats have individual heat meters to save energy and to ensure a fair distribution of the cost. If all flats have the same indoor temperature, the distribution is correct. In practice, the inhabitants of the different flats maintain......It is well known that similar flats in a block do not have the same energy demand. Part of the explanation for this is the location of the flat in the building, e.g. on the top floor, at the house end or in the middle of the building. It is possible to take this into account when the heating bill...... different indoor temperatures. The result is that heat flows between individual flats. This decreases the energy consumption in the flat where the owner maintains a lower temperature. The neighbouring flats will have higher energy consumption. Calculations were performed for Danish blocks of flats from 1920...

  17. Rocky Flats Compliance Program

    International Nuclear Information System (INIS)

    The Department of Energy (DOE) established the Office of Technology Development (EM-50) (OTD) as an element of Environmental Restoration and Waste Management (EM) in November 1989. The primary objective of the Office of Technology Development, Rocky Flats Compliance Program (RFCP), is to develop altemative treatment technologies for mixed low-level waste (wastes containing both hazardous and radioactive components) to use in bringing the Rocky Flats Plant (RFP) into compliance with Federal and state regulations and agreements. Approximately 48,000 cubic feet of untreated low-level mixed waste, for which treatment has not been specified, are stored at the RFP. The cleanup of the Rocky Flats site is driven by agreements between DOE, the Environmental Protection Agency (EPA), and the Colorado Department of Health (CDH). Under these agreements, a Comprehensive Treatment and Management Plan (CTMP) was drafted to outline the mechanisms by which RFP will achieve compliance with the regulations and agreements. This document describes DOE's strategy to treat low-level mixed waste to meet Land Disposal Restrictions and sets specific milestones related to the regulatory aspects of technology development. These milestones detail schedules for the development of technologies to treat all of the mixed wastes at the RFP. Under the Federal Facilities Compliance Act (FFCA), the CTMP has been incorporated into Rocky Flats Plant Conceptual Site Treatment Plan (CSTP). The CSTP will become the Rocky Flats Plant site Treatment Plan in 1995 and will supersede the CTMP

  18. Study of the Non-enzymatic Glucose Sensor Based on Single-crystalline Porous Palladium Nanoflowers%基于单晶多孔钯纳米花的无酶型葡萄糖传感器研究

    Institute of Scientific and Technical Information of China (English)

    王强; 王其钰; 祁琨; 管伟明; 崔小强

    2015-01-01

    The preparation method of single-crystalline porous Palladium nanoflowers and electrocatalytic performance for non-enzymatic glucose biosensor was studied. As-prepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), which confirm that the Palladium nanoflowers are single- crystalline nature and enclosed by {100} facets. Palladium nanocubes and Palladium nanooctahedrons with the same size as Palladium nanoflower were prepared, electrocatalytic performance for non- enzymatic glucose biosensor of three nanoparticles were compared. Experimental results show that Palladium nanoflowers and nanocubes enclosed by {100} have better catalytic performance than Palladium nanooctahedrons enclosed by {111} for non-enzymatic glucose biosensor. Single-crystalline porous Palladium nanoflowers have the best catalytic performance, good stability and resistance to interferences. The detection range is 0.05~6.5 mmol/L (R2=0.9984), with a detection limit of 1 µmol/L (signal-to-noise ratio of 3), and a sensitivity of 1.1721 µA/(mmol/L cm2).%悁究了单晶多孔钯纳米花的制备惣及它作为无酶型葡萄糖传感器的催化性能。通过XRD、TEM惣及HRTEM表征手段证实合成的产物为惣{100}为主导晶面的单晶多孔钯纳米花,并合成了与钯纳米花尺寸相近的钯纳米立方体和钯纳米八面体,比较了3种纳米粒子对葡萄糖的催化能力。实悚结果表明,惣{100}为主导晶面的单晶多孔钯纳米花和钯纳米立方体对葡萄糖的催化活性优于惣{111}为主导晶面的钯纳米八面体。单晶多孔的钯纳米花是3者中催化活性最强,具有较好的稳定性惣及抗干扰能力,检测范围为0.05~6.5 mmol/L (R2=0.9984),最低检测限为1µmol/L (S/N=3),灵敏度为1.1721µA/(mmol/L cm2)。

  19. Flat flame burner

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Y.; Mitsudomi, H.

    1976-02-24

    Osaka Gas Co., Ltd.'s new flat-flame heat-treatment burner offers lower material costs, reduced combustion noise, and elimination of the need for a high-pressure fuel gas to provide a high-velocity combustion burner. The flat-flame burner contains an air-swirling chamber with a flame opening in one side; the wall defining the flame opening has a small thickness around the opening and a flat outer face. This construction causes the combustion gas to be forced out from the flame opening in a spiral direction by the swirling air current within the air chamber; together with the orifice effect of permitting the flame to emanate from a small opening to an unconfined outer space, this helps assure the formation of a flat flame spreading out over a very wide area for very rapid, uniform, and highly efficient heat treatment of an article to be heated. This approach also permits the thickness of the overall device to be reduced. The supply of combustion air in the form of a swirling stream makes it possible to provide a high-velocity combustion burner without using a high-pressure fuel gas, with the advantage of satisfactory mixture of the fuel gas and combustion air and consequently markedly reduced combustion noise.

  20. Fabricating metal-oxide-semiconductor field-effect transistors on a polyethylene terephthalate substrate by applying low-temperature layer transfer of a single-crystalline silicon layer by meniscus force

    Energy Technology Data Exchange (ETDEWEB)

    Sakaike, Kohei; Akazawa, Muneki; Nakamura, Shogo [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, Hiroshima 739-8530 (Japan); Higashi, Seiichiro [Department of Semiconductor Electronics and Integration Science, Graduate School of Advanced Sciences of Matter, Hiroshima University, Kagamiyama 1-3-1, Higashihiroshima, Hiroshima 739-8530 (Japan); Research Institute for Nanodevice and Bio Systems, Hiroshima University, Kagamiyama 1-4-2, Higashihiroshima, Hiroshima 739-8527 (Japan)

    2013-12-02

    A low-temperature local-layer technique for transferring a single-crystalline silicon (c-Si) film by using a meniscus force was proposed, and an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) was fabricated on polyethylene terephthalate (PET) substrate. It was demonstrated that it is possible to transfer and form c-Si films in the required shape at the required position on PET substrates at extremely low temperatures by utilizing a meniscus force. The proposed technique for layer transfer was applied for fabricating high-performance c-Si MOSFETs on a PET substrate. The fabricated MOSFET showed a high on/off ratio of more than 10{sup 8} and a high field-effect mobility of 609 cm{sup 2} V{sup −1} s{sup −1}.

  1. Superconducting properties of single crystalline FeTe1-xSex (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50)

    International Nuclear Information System (INIS)

    In this paper we have grown single crystalline samples of Se-doped FeTe compound using self-flux technique and studied the structural and electrical transport properties of the as-grown crystals. The samples have been grown with compositions FeTe1-xSex (x = 0, 0.15, 0.25, 0.35, 0.40 and 0.50). The as-grown samples are then investigated for their structural and superconducting properties by means of X-ray diffraction and physical property measurements. The XRD results of powdered samples reveal a single (tetragonal) phase with space group symmetry P4/nmm for all the samples. The lattice parameters are observed to reduce with increase of Se-doping at Te-site. Highest Hc2(0) (∼180 T) value has been observed for FeTe0.5Se0.5 sample

  2. One-step in-diffusion as a result of multipulse laser irradiation of LiNbO3 single-crystalline substrates covered with thin Ti deposits on the effect of the radiation wavelength

    International Nuclear Information System (INIS)

    We studied Ti in-diffusion as an effect of multiple laser irradiation, in either visible of ultraviolet (u.v.) spectral ranges, of LiNbO3 single-crystalline structures with Ti coatings of two different thickness. It is shown that while u.v. (excimer, λ approx. 308 nm) laser irradiation causes a complete expulsion of the Ti deposit, the visible (ruby, λ approx. 694.3 nm) laser irradiation at intermediate incident laser fluence (up to approx. 0.7J cm-2) promotes efficient Ti in-diffusion from the thin (400 A width) Ti deposit down to a micrometre range implantation depth. (author). 7 refs, 6 figs

  3. The Critical Effect of Niobium Doping on the Formation of Mesostructured TiO2 : Single-Crystalline Ordered Mesoporous Nb-TiO2 and Plate-like Nb-TiO2 with Ordered Mesoscale Dimples.

    Science.gov (United States)

    Kitahara, Masaki; Shimasaki, Yuta; Matsuno, Takamichi; Kuroda, Yoshiyuki; Shimojima, Atsushi; Wada, Hiroaki; Kuroda, Kazuyuki

    2015-09-01

    Highly ordered mesoporous niobium-doped TiO2 with a single-crystalline framework was prepared by using silica colloidal crystals with ca. 30 nm in diameter as templates. The preparation of colloidal crystals composed of uniform silica nanoparticles is a key to obtain highly ordered mesoporous Nb-doped TiO2 . The XPS measurements of Nb-doped TiO2 showed the presence of Nb(5+) and correspondingly Ti(3+) . With the increase in the amount of doped Nb, the crystalline phase of the product was converted from rutile into anatase, and the lattice spacings of both rutile and anatase phases increased. Surprisingly, the increase in the amount of Nb led to the formation of plate-like TiO2 with dimpled surfaces on one side, which was directly replicated from the surfaces of the colloidal silica crystals. PMID:26216465

  4. Luminescent and scintillation properties of Bi{sup 3+} doped Y{sub 2}SiO{sub 5} and Lu{sub 2}SiO{sub 5} single crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu., E-mail: zorenko@ukw.edu.pl [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Gorbenko, V.; Zorenko, T. [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Laboratory for Optoelectronic Materials (LOM), Department of Electronics of Ivan Franko National University of Lviv, 79017 Lviv (Ukraine); Malinowski, P. [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85-090 Bydgoszcz (Poland); Jary, V.; Kucerkova, R.; Beitlerova, A.; Mares, J.A.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16253 Prague (Czech Republic); Fedorov, A. [Institute for Single Crystals NAS of Ukraine, 60 Lenin ave., 61001 Kharkiv (Ukraine)

    2014-10-15

    In this paper we report our follow-up research on the Bi{sup 3+} luminescence in orthosilicate compounds, focusing on absorption, luminescent and scintillation properties of YSO:Bi and LSO:Bi SCFs with the Bi concentration ranging from 0.05 to 0.18 at%. For purpose of this research, single crystalline films (SCF) of Y{sub 2}SiO{sub 5}:Bi and Lu{sub 2}SiO{sub 5}:Bi have been grown by the LPE method onto YSO and LSO substrates from the melt-solution based on Bi{sub 2}O{sub 3} flux. - Highlights: • YSO:Bi and LSO:Bi films have been grown by liquid phase epitaxy. • Bi{sup 3+} absorption and luminescence depends on Bi concentration. • Scintillation properties of YSO:Bi and LSO:Bi films have been studied.

  5. Facile hydrothermal synthesis of single crystalline TiOF2 nanocubes and their phase transitions to TiO2 hollow nanocages as anode materials for lithium-ion battery

    International Nuclear Information System (INIS)

    Highlights: ► Using titanium (IV) isopropoxide as titanium source to fabiricate the uniform single crystalline TiOF2 nanocubes with edge length of around 200–300 nm. ► Confirm that acetic acid play a crucial role in TiO2 hollow structure formation. ► Both such nanosized TiOF2 and hollow cubic TiO2 nanocage with dominantly exposed {0 0 1} crystal planes have not yet been synthesized for lithium ion battery application presently, furthermore, exhibit outstanding electrochemical properties. - Abstract: Single-crystalline TiOF2 nanocubes with edge length of around 200–300 nm have been synthesized under hydrothermal conditions using titanium (IV) isopropoxide (TIP) as titanium source, HF as etchant. The corresponding hollow TiO2 nanocages with dominantly exposed {0 0 1} crystal planes can be easily obtained by calcinating TiOF2 nanocubes under air atmosphere. It is also found that the presence of acetic acid not only being chemical modifier of TIP to lower its reactivity at relatively acid environment, but also gives rise to a uniform hollow TiO2 nanocages which play the crucial role in hollow formation. The TiOF2 electrode presented here exhibits much excellent electrochemical performance. The initial high specific capacity of TiOF2 can be up to 1045 mAh g−1 at a rate of 30 mA g−1. The specific discharge capacity is 510 mAh g−1 after 40 cycles.

  6. Synthesis and measurements of the optical bandgap of single crystalline complex metal oxide BaCuV{sub 2}O{sub 7} nanowires by UV–VIS absorption

    Energy Technology Data Exchange (ETDEWEB)

    Shakir, Imran, E-mail: shakir@skku.edu [Sustainable Energy Technologies Center, King Saudi University, PO-BOX 800, Riyadh 11421 (Saudi Arabia); Shahid, Muhammad [Sustainable Energy Technologies Center, King Saudi University, PO-BOX 800, Riyadh 11421 (Saudi Arabia); Aboud, Mohamed F.A. [Sustainable Energy Technologies Center, King Saudi University, PO-BOX 800, Riyadh 11421 (Saudi Arabia); Mining and Petroleum Engineering Department, Faculty of Engineering, Al-Azhar University, Nasr City 11371, Cairo (Egypt)

    2015-08-25

    Highlights: • Synthesis of single crystalline complex metal oxides BaCuV{sub 2}O{sub 7} nanowires. • Surfactant free, economically favorable chemical solution deposition method. • Complex metal oxides nanowires with controlled stoichiometry. • Simply controlling the temperature and thickness of the coated film, we can easily obtain high quality BaCuV{sub 2}O{sub 7} nanowires. - Abstract: The synthesis of single crystalline complex metal oxides BaCuV{sub 2}O{sub 7} nanowires were attained by using surfactant free, economically favorable chemical solution deposition method. A thin layer of BaCuV{sub 2}O{sub 7} nanocrystals is formed by the decomposition of complex metal oxide solution at 150 °C to provide nucleation sites for the growth of nanowires. The synthesized nanowires were typically 1–5 μm long with diameter from 50 to 150 nm. We showed that by simply controlling the temperature and thickness of the coated film, we can easily obtain high quality BaCuV{sub 2}O{sub 7} nanowires. The UV–VIS absorption spectra show indirect bandgap of 2.65 ± 0.05 eV of nanowires. The temperature-dependent resistances of BaCuV{sub 2}O{sub 7} nanowires agree with the exponential correlation, supporting that the conducting carriers are the quasi-free electrons. We believe that our methodology will provides a simple and convenient route for the synthesis of variety of complex metal oxides nanowires with controlled stoichiometry.

  7. Flat flame burner

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Y.; Mitsudomi, H.

    1976-03-09

    Osaka Gas Co., Ltd.'s new flat-flame burner has an air-swirling chamber with a flame opening in one side so constructed that combustion gas is forced out from the flame opening in a spiral direction by the swirling air current within the air chamber. The orifice effect of permitting the flame to emanate from a small opening to an unconfined outer space assures formation of a flat flame spreading out over a very wide area, thereby ensuring very rapid, uniform and highly efficient heat treatment of an article to be heated. With the present invention, moreover, it is possible to materially reduce the thickness of the overall device.

  8. Flat covers of modules

    CERN Document Server

    Xu, Jinzhong

    1996-01-01

    Since the injective envelope and projective cover were defined by Eckmann and Bas in the 1960s, they have had great influence on the development of homological algebra, ring theory and module theory. In the 1980s, Enochs introduced the flat cover and conjectured that every module has such a cover over any ring. This book provides the uniform methods and systematic treatment to study general envelopes and covers with the emphasis on the existence of flat cover. It shows that Enochs' conjecture is true for a large variety of interesting rings, and then presents the applications of the results. Readers with reasonable knowledge in rings and modules will not have difficulty in reading this book. It is suitable as a reference book and textbook for researchers and graduate students who have an interest in this field.

  9. Preparation of flat gold terraces for protein chip developments

    OpenAIRE

    Elie-Caille, Céline; Rauch, Jean-Yves; Rouleau, Alain; Boireau, Wilfrid

    2009-01-01

    A simple method to prepare flat gold terraces on mica for atomic force microscopy biomolecular characterisation is described. The procedure includes preheating of the substrate, metal deposition and an annealing step. All of these steps are at elevated temperatures (300–420°C). This approach allows one to prepare large flat gold terraces (200– 500 nm), which constitute ideal substrates for visualisation and characterisation of a self-assembly monolayer of biomolecules at the nanoscale. The au...

  10. Flat Earth图片

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    欢迎来到这期的光盘介绍。本月的附刊光盘中,除了每月的精彩教程外,您可在光盘中找到15张由Flat Earth友情提供的库存图片。当然还有Twixtor和最新的Acrobat Reader 7。

  11. Exact Piecewise Flat Gravitational Waves

    OpenAIRE

    van de Meent, Maarten

    2011-01-01

    We generalize our previous linear result [1] in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to construct a piecewise flat spacetime that describes an impulsive plane wavefront. From these wavefronts more general plane waves may be constructed.

  12. In situ direct growth of single crystalline metal (Co, Ni) selenium nanosheets on metal fibers as counter electrodes toward low-cost, high-performance fiber-shaped dye-sensitized solar cells

    Science.gov (United States)

    Chen, Liang; Yin, Hexing; Zhou, Yong; Dai, Hui; Yu, Tao; Liu, Jianguo; Zou, Zhigang

    2016-01-01

    Highly crystalline metal (Co, Ni) selenium (Co0.85Se or Ni0.85Se) nanosheets were in situ grown on metal (Co, Ni) fibers (M-M0.85Se). Both M-M0.85Se (Co-Co0.85Se and Ni-Ni0.85Se) fibers prove to function as excellent, low-cost counter electrodes (CEs) in fiber-shaped dye-sensitized solar cells (FDSSCs) with high power conversion efficiency (Co-Co0.85Se 6.55% and Ni-Ni0.85Se 7.07%), comparable or even superior to a Pt fiber CE (6.54%). The good performance of the present Pt-free CE-based solar cell was believed to originate from: (1) the intrinsic electrocatalytic properties of the single-crystalline M-M0.85Se (2) the enough void space among M0.85Se nanosheets that allows easier redox ion diffusion; (3) the two-dimensional morphology that provides a large contact area between the CE catalytic material and electrolyte; (4) in situ direct growth of the M0.85Se on metal fibers that renders good electrical contact between the active material and the electron collector.Highly crystalline metal (Co, Ni) selenium (Co0.85Se or Ni0.85Se) nanosheets were in situ grown on metal (Co, Ni) fibers (M-M0.85Se). Both M-M0.85Se (Co-Co0.85Se and Ni-Ni0.85Se) fibers prove to function as excellent, low-cost counter electrodes (CEs) in fiber-shaped dye-sensitized solar cells (FDSSCs) with high power conversion efficiency (Co-Co0.85Se 6.55% and Ni-Ni0.85Se 7.07%), comparable or even superior to a Pt fiber CE (6.54%). The good performance of the present Pt-free CE-based solar cell was believed to originate from: (1) the intrinsic electrocatalytic properties of the single-crystalline M-M0.85Se (2) the enough void space among M0.85Se nanosheets that allows easier redox ion diffusion; (3) the two-dimensional morphology that provides a large contact area between the CE catalytic material and electrolyte; (4) in situ direct growth of the M0.85Se on metal fibers that renders good electrical contact between the active material and the electron collector. Electronic supplementary information (ESI

  13. Growth and luminescent properties of scintillators based on the single crystalline films of Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12}:Ce garnet

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Yu, E-mail: zorenko@ukw.edu.pl [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85090 Bydgoszcz (Poland); Laboratory for Optoelectronic Materials, Department of Electronics of Ivan Franko National University of Lviv, 79017 Lviv (Ukraine); Gorbenko, V. [Institute of Physics, Kazimierz Wielki University in Bydgoszcz, 85090 Bydgoszcz (Poland); Laboratory for Optoelectronic Materials, Department of Electronics of Ivan Franko National University of Lviv, 79017 Lviv (Ukraine); Vasylkiv, Ja [Laboratory for Optoelectronic Materials, Department of Electronics of Ivan Franko National University of Lviv, 79017 Lviv (Ukraine); Zelenyj, A. [Danylo Halytskyy Lviv National Medical University, 79010 Lviv (Ukraine); Fedorov, A. [Institute for Scintillation Materials, NAS of Ukraine, 61001 Kharkiv (Ukraine); Kucerkova, R.; Mares, J.A.; Nikl, M. [Institute of Physics, AS CR, 16253 Prague (Czech Republic); Bilski, P.; Twardak, A. [Institute of Nuclear Physic, Polish Academy of Science, 31-342 Krakow (Poland)

    2015-04-15

    Highlights: • Single crystalline films of Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12} garnets at x = 0 ÷ 3.0 were grown by LPE method onto YAG substrates. • Lattice constant of Lu{sub 3−}Gd{sub x}Al{sub 5}O{sub 12}:Ce film and the misfit m between films and YAG substrate changed linearly with increasing of Gd content. • Effective Gd{sup 3+}–Ce{sup 3+} energy transfer occurs in the Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12}:Ce films. • Best scintillation light yield is observed in the Lu{sub 3}Al{sub 5}O{sub 12}:Ce and Lu{sub 2.4}Gd{sub 0.6}Al{sub 5}O{sub 12}:Ce films. • Increase of the Gd content in x = 1.5–2.5 range results in decreasing the scintillation LY of Lu{sub 3−x}Gd{sub x}Al{sub 5}O{sub 12}:Ce films. - Abstract: The work is related to the growth of scintillators based on the single crystalline films (SCF) of Ce{sup 3+} doped Lu{sub 3−}Gd{sub x}Al{sub 5}O{sub 12} mixed rare-earth garnets by Liquid Phase Epitaxy (LPE) method. We have shown, that full set of Lu{sub 3−}Gd{sub x}Al{sub 5}O{sub 12} SCFs with x values ranging from 0 to 3.0 can be successfully crystallized by the LPE method onto Y{sub 3}Al{sub 5}O{sub 12} (YAG) substrates from the melt-solutions based on PbO-B{sub 2}O{sub 3} flux. The absorption, X-ray excited luminescence, photoluminescence, thermoluminescence and light yield measurements, the latter under excitation by α-particles of {sup 239}Pu and {sup 241}Am radioisotopes, were applied for their characterization.

  14. Temperature-modulated annealing of c-plane sapphire for long-range-ordered atomic steps

    Science.gov (United States)

    Yatsui, Takashi; Kuribara, Kazunori; Sekitani, Tsuyoshi; Someya, Takao; Yoshimoto, Mamoru

    2016-03-01

    High-quality single-crystalline sapphire is used to prepare various semiconductors because of its thermal stability. Here, we applied the tempering technique, which is well known in the production of chocolate, to prepare a sapphire substrate. Surprisingly, we successfully realised millimetre-range ordering of the atomic step of the sapphire substrate. We also obtained a sapphire atomic step with nanometre-scale uniformity in the terrace width and atomic-step height. Such sapphire substrates will find applications in the preparation of various semiconductors and devices.

  15. Detection and imaging of the oxygen deficiency in single crystalline YBa{sub 2}Cu{sub 3}O{sub 7−δ} thin films using a scanning positron beam

    Energy Technology Data Exchange (ETDEWEB)

    Reiner, M.; Gigl, T.; Hugenschmidt, C. [Lehrstuhl E21 at Physics Department and FRM II at Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, James-Franck Straße, 85748 Garching (Germany); Jany, R.; Hammerl, G. [Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg, Universitätsstraße 1, 86135 Augsburg (Germany)

    2015-03-16

    Single crystalline YBa{sub 2}Cu{sub 3}O{sub 7−δ} (YBCO) thin films were grown by pulsed laser deposition in order to probe the oxygen deficiency δ using a mono-energetic positron beam. The sample set covered a large range of δ (0.191 < δ < 0.791) yielding a variation of the critical temperature T{sub c} between 25 and 90 K. We found a linear correlation between the Doppler broadening of the positron electron annihilation line and δ determined by X-ray diffraction. Ab-initio calculations have been performed in order to exclude the presence of Y vacancies and to ensure the negligible influence of potentially present Ba or Cu vacancies to the found correlation. Moreover, scanning with the positron beam allowed us to analyze the spatial variation of δ, which was found to fluctuate with a standard deviation of up to 0.079(5) within a single YBCO film.

  16. Novel porous single-crystalline ZnO nanosheets fabricated by annealing ZnS(en)0.5 (en = ethylenediamine) precursor. Application in a gas sensor for indoor air contaminant detection

    International Nuclear Information System (INIS)

    Novel single-crystalline ZnO nanosheets with porous structure have been fabricated by annealing ZnS(en)0.5 (en = ethylenediamine) complex precursor. The morphology and structure observations performed by field emission scanning electronic microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) indicate that numerous mesopores with a diameter of about 26.1 nm distribute all through each nanosheet with a high density. The transformation of structure and composition of samples obtained during thermal treatment processes were investigated by x-ray diffraction (XRD), x-ray photoelectron spectrometry (XPS), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) absorption spectroscopy. The formation mechanism of the porous structure is proposed. For indoor air contaminant detection in which formaldehyde and ammonia are employed as target gases, the as-prepared ZnO nanosheets were applied for the fabrication of gas sensors. It was found that the as-fabricated sensors not only exhibit highly sensitive performance, e.g., high gas-sensing responses, short response and recovery time, but also possess significant long-term stability. It is indicated that these ZnO nanostructures could promisingly be applied in electronic devices for environmental evaluation.

  17. Effects of high-energy proton irradiation on the density and Hall mobility of majority carriers in single crystalline n-type CuInSe2 thin films

    International Nuclear Information System (INIS)

    Proton irradiation effects in CuInSe2 (CIS) thin films have been investigated as a function of proton energy (0.38, 1 and 3 MeV). Single crystalline n-CIS thin films were prepared by radio frequency sputtering. The electrical properties of as-grown and irradiated samples were measured. The typical electron concentration and Hall mobility in as-grown samples were 4 x 1016 cm-3 and 120 cm2/Vs, respectively. After 0.38 and 1MeV proton irradiation, both of the electron concentration and Hall mobility were decreased as the fluence exceeded 1 x 1013 cm-2, but for 3 MeV proton irradiation, they were decreased over the fluence of 1 x 1014 cm-2. The damage by high-energy proton irradiation was lower than that by low-energy proton irradiation. The carrier removal rate with proton fluence was estimated about from 1800 to 300 cm-1as proton energy was changed from 0.38 to 3 MeV. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. IS THE WORLD FLAT?

    Directory of Open Access Journals (Sweden)

    Cristian Încalţărău

    2010-06-01

    Full Text Available Globalization became more and more prominent during the last decades. There is no way to argue that globalization led to more interconnected economies, facilitating the communication and the collaboration around the world. But where is this going? Doesglobalization mean uniformity or diversity? As the world begins to resemble more, the people are trying to distinguish between them more, which can exacerbate nationalistic feeling. Friedman argues that globalization made the world smaller and flatter, allowing all countries to take chance of the available opportunities equally. But is this really true? Although politic and cultural factors can stand in front of a really flat world, what is the key for Chinese and Indian success and which are theirs perspectives?

  19. Flat Helical Nanosieves

    CERN Document Server

    Mei, Shengtao; Hussain, Sajid; Huang, Kun; Ling, Xiaohui; Siew, Shawn Yohanes; Liu, Hong; Teng, Jinghua; Danner, Aaron; Qiu, Cheng-Wei

    2016-01-01

    Compact and miniaturized devices with flexible functionalities are always highly demanded in optical integrated systems. Plasmonic nanosieve has been successfully harnessed as an ultrathin flat platform for complex manipulation of light, including holography, vortex generation and non-linear processes. Compared with most of reported single-functional devices, multi-functional nanosieves might find more complex and novel applications across nano-photonics, optics and nanotechnology. Here, we experimentally demonstrate a promising roadmap for nanosieve-based helical devices, which achieves full manipulations of optical vortices, including its generation, hybridization, spatial multiplexing, focusing and non-diffraction propagation etc., by controlling the geometric phase of spin light via over 121 thousands of spatially-rotated nano-sieves. Thanks to such spin-conversion nanosieve helical elements, it is no longer necessary to employ the conventional two-beam interferometric measurement to characterize optical ...

  20. Flat Bands Under Correlated Perturbations

    OpenAIRE

    Bodyfelt, Joshua D.; Leykam, Daniel; Danieli, Carlo; Yu, Xiaoquan; Flach, Sergej

    2014-01-01

    Flat band networks are characterized by coexistence of dispersive and flat bands. Flat bands (FB) are generated by compact localized eigenstates (CLS) with local network symmetries, based on destructive interference. Correlated disorder and quasiperiodic potentials hybridize CLS without additional renormalization, yet with surprising consequencies: (i) states are expelled from the FB energy $E_{FB}$, (ii) the localization length of eigenstates vanishes as $\\xi \\sim 1 / \\ln (E- E_{FB})$, (iii)...

  1. More Ricci-flat branes

    CERN Document Server

    Figueroa-O'Farrill, J M

    1999-01-01

    Certain supergravity solutions (including domain walls and the magnetic fivebrane) have recently been generalised by Brecher and Perry by relaxing the condition that the brane worldvolume be flat. In this way they obtain examples in which the brane worldvolume is a static spacetime admitting parallel spinors. In this note we simply point out that the restriction to static spacetimes is unnecessary, and in this way exhibit solutions where the brane worldvolume is an indecomposable Ricci-flat lorentzian manifold admitting parallel spinors. We discuss more Ricci-flat fivebranes and domain walls, as well as new Ricci-flat D3-branes.

  2. Is classical flat Kasner spacetime flat in quantum gravity?

    Science.gov (United States)

    Singh, Parampreet

    2016-05-01

    Quantum nature of classical flat Kasner spacetime is studied using effective spacetime description in loop quantum cosmology (LQC). We find that even though the spacetime curvature vanishes at the classical level, nontrivial quantum gravitational effects can arise. For the standard loop quantization of Bianchi-I spacetime, which uniquely yields universal bounds on expansion and shear scalars and results in a generic resolution of strong singularities, we find that a flat Kasner metric is not a physical solution of the effective spacetime description, except in a limit. The lack of a flat Kasner metric at the quantum level results from a novel feature of the loop quantum Bianchi-I spacetime: quantum geometry induces nonvanishing spacetime curvature components, making it not Ricci flat even when no matter is present. The noncurvature singularity of the classical flat Kasner spacetime is avoided, and the effective spacetime transits from a flat Kasner spacetime in asymptotic future, to a Minkowski spacetime in asymptotic past. Interestingly, for an alternate loop quantization which does not share some of the fine features of the standard quantization, flat Kasner spacetime with expected classical features exists. In this case, even with nontrivial quantum geometric effects, the spacetime curvature vanishes. These examples show that the character of even a flat classical vacuum spacetime can alter in a fundamental way in quantum gravity and is sensitive to the quantization procedure.

  3. Graphene nanoribbons production from flat carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Melo, W. S.; Guerini, S.; Diniz, E. M., E-mail: eduardo.diniz@ufma.br [Departamento de Física, Universidade Federal do Maranhão, São Luís - MA 65080-805 (Brazil)

    2015-11-14

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons.

  4. Graphene nanoribbons production from flat carbon nanotubes

    International Nuclear Information System (INIS)

    Graphene nanoribbons are of great interest for pure and applied sciences due to their unique properties which depend on the nanoribbon edges, as, for example, energy gap and antiferromagnetic coupling. Nevertheless, the synthesis of nanoribbons with well-defined edges remains a challenge. To collaborate with this subject, here we propose a new route for the production of graphene nanoribbons from flat carbon nanotubes filled with a one-dimensional chain of Fe atoms by first principles calculations based on density functional theory. Our results show that Fe-filled flat carbon nanotubes are energetically more stable than non flattened geometries. Also we find that by hydrogenation or oxygenation of the most curved region of the Fe-filled flat armchair carbon nanotube, it occurred a spontaneous production of zigzag graphene nanoribbons which have metallic or semiconducting behavior depending on the edge and size of the graphene nanoribbon. Such findings can be used to create a new method of synthesis of regular-edge carbon nanoribbons

  5. Exact piecewise flat gravitational waves

    NARCIS (Netherlands)

    van de Meent, M.

    2011-01-01

    We generalize our previous linear result (van de Meent 2011 Class. Quantum Grav 28 075005) in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to constr

  6. Asymptotic Flatness in Rainbow Gravity

    OpenAIRE

    Hackett, Jonathan

    2005-01-01

    A construction of conformal infinity in null and spatial directions is constructed for the Rainbow-flat space-time corresponding to doubly special relativity. From this construction a definition of asymptotic DSRness is put forward which is compatible with the correspondence principle of Rainbow gravity. Furthermore a result equating asymptotically flat space-times with asymptotically DSR spacetimes is presented.

  7. Irritated Method for Flat warts

    Institute of Scientific and Technical Information of China (English)

    LiBingxu

    2004-01-01

    Summary Background The relation between spontaneous regression of Flat warts and T cells depended immunity was confirmed. Cells immunity against HPV was induced by presenting of HPV related antigens, and thrived by cytokine and some chemistry agent. So how to make HPV which incubated in keratinocyte to present PHV antigens and keratinocyte to secret cytokine or chemistry agents should be a pursuance for dermatologist who are looking for a efficient method to deal with flat warts. Present research had exhibited inflammable agents can induce dermatitis when apply to the skin surface, so it might bring flat warts to spontaneous regression. Objective To observe the effectiveness of irritant drugs on flat warts, and at same time to understand more on the mechanism of the regression. Methods Compared with Control we treat 88 case of flat warts with retinoid gel or 3% hydrogen peroxide solution plus 5 % salicylic acid cream (HPSC). Results Both retinoid gel and HPSC reveal significant effect on flat warts. Conclusion Retinoid gel or SPHC was effective on the treatment of flat warts. The possible explanation for this is the drugs when put on the skin will induce dermatitis and dissolve or denude keratin.

  8. Is classical flat Kasner spacetime flat in quantum gravity?

    OpenAIRE

    Singh, Parampreet

    2016-01-01

    Quantum nature of classical flat Kasner spacetime is studied using effective spacetime description in loop quantum cosmology. We find that even though the spacetime curvature vanishes at the classical level, non-trivial quantum gravitational effects can arise. For the standard loop quantization of Bianchi-I spacetime, which uniquely yields universal bounds on expansion and shear scalars and results in a generic resolution of strong singularities, we find that a flat Kasner metric is not a phy...

  9. X-ray photoelectron diffraction for pure and Nb-doped KTaO3: site determination for the Nb atoms

    International Nuclear Information System (INIS)

    We present a set of polar-angle-dependent x-ray photoelectron spectra (XPS) obtained from in situ cleaved single-crystalline pure KTaO3. The variation of the intensity for different angles can be explained by the diffraction of the emitted electrons by the surrounding atoms of the emitter and thus may be used as a 'fingerprint' for the location of emitting impurity atoms. Measurements were carried out on niobium-doped KTaO3. The atomic position of the niobium atoms was deduced from the comparison of the angle-dependent spectra, giving a clear hint that tantalum is replaced by niobium. (author)

  10. Is classical flat Kasner spacetime flat in quantum gravity?

    CERN Document Server

    Singh, Parampreet

    2016-01-01

    Quantum nature of classical flat Kasner spacetime is studied using effective spacetime description in loop quantum cosmology. We find that even though the spacetime curvature vanishes at the classical level, non-trivial quantum gravitational effects can arise. For the standard loop quantization of Bianchi-I spacetime, which uniquely yields universal bounds on expansion and shear scalars and results in a generic resolution of strong singularities, we find that a flat Kasner metric is not a physical solution of the effective spacetime description, except in a limit. The lack of a flat Kasner metric at the quantum level results from a novel feature of the loop quantum Bianchi-I spacetime: quantum geometry induces non-vanishing spacetime curvature components, making it not Ricci flat even when no matter is present. The non-curvature singularity of the classical flat Kasner spacetime is avoided, and the effective spacetime transits from a flat Kasner spacetime in asymptotic future, to a Minkowski spacetime in asym...

  11. Lu.sub.2./sub.SiO.sub.5./sub.:Ce and Y.sub.2./sub.SiO.sub.5./sub.:Ce single crystals and single crystalline film scintillators: comparison of the luminescent and scintillation properties

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Voznyak, T.; Grinyov, B.; Sidletskiy, O.; Fedorov, A.; Gerasymov, I.; Jarý, Vítězslav; Mareš, Jiří A.; Beitlerová, Alena; Nikl, Martin; Dlouhý, Jaroslav; Jurek, Karel

    Halle(Saale) : Martin Luther University of Halle-Wittenberg, 2012 - (Schweizer, S.; Ahrens, B.). O-Tue-09-O-Tue-09 [International Conference on Luminescent Detectors and Transformers of Ionizing Radiation 2012 /8./, LUMDETR 2012. 10.09.2012-14.09.2012, Halle (Saale)] Institutional research plan: CEZ:AV0Z10100521 Keywords : Lu 2 SiO 5 and Y 2 SiO 5 * single crystalline film * scintillators Subject RIV: BM - Solid Matter Physics ; Magnetism

  12. Research on Flat Solar Collector

    OpenAIRE

    Kavolynas, Antanas

    2005-01-01

    The Thesis analyzes one of the spheres of alternative energy supply – the solar energy. The main objective of the Thesis is to determine the energy rates of the solar collector and its accumulative capacity. The Paper introduces a stand on the solar collector research which consists of a flat solar collector, heat accumulator and auxiliary equipment. The research object of the Thesis is a laboratory flat solar collector and its system. The Thesis analyses the constructions of the solar collec...

  13. Fabrication of Y1-xRE xBa2Cu3O y films on single crystalline substrates and IBAD buffered metallic tapes by advanced TFA-MOD process

    International Nuclear Information System (INIS)

    We fabricated Y1-xSm xBa2Cu3O y and YSm xBa2Cu3O y (YSmBCO) films on SrTiO3 (STO) single crystalline substrates and IBAD buffered metallic tapes (PLD-CeO2/IBAD-GZO/Hastelloy) by the advanced TFA-MOD process by mixing TFA salts of Y, Sm, Ba and Cu naphthenate, and tried to improve the superconductivity properties compared with those of the pure YBa2Cu3O7-δ (YBCO). As a result, J c values of Y1-xSm xBa2Cu3O y films with x = 0.05 or 0.3, which were fabricated on STO substrates, were improved under the high magnetic fields compared with those of the YBCO without substitution. However, Sm segregation was detected near the STO substrate which was obtained by the TEM-EDS (transmission electron microscopy-energy-dispersive X-ray spectroscopy) analysis. On the other hand, Y1-xSm xBa2Cu3O y films with x = 0.05 and YSm xBa2Cu3O y films with x = 0.3, which were fabricated on IBAD buffered metallic substrates, also improved I c value under the high magnetic fields compared with those of the YBCO without substitution. Moreover, from the TEM-EDS analysis, Y or Sm segregation was not found. The difference in the Sm segregation behavior between the film on STO and CeO2 buffered substrates could be explained by the difference in the ratios of the misfit parameters between YBCO/substrate and SmBCO/substrate. Additionally, it was considered that the above phenomenon might be unique in the MOD system and could not be observed in the PLD system, because of the difference in the crystal growth mechanism. In the film of YSm0.3Ba2Cu3O y, we observed the grains of (Y, Sm)2O3 and (Y, Sm)2Cu2O5 by TEM observation. We will further investigate the origin of pinning centers

  14. Bi{sup 3+}–Pr{sup 3+} energy transfer processes and luminescent properties of LuAG:Bi,Pr and YAG:Bi,Pr single crystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Zorenko, Y., E-mail: zorenko@ukw.edu.pl [Institute of Physics of Kazimierz Wielki University in Bydgoszcz, Powstańców Wielkopolskich str., 2, 85-090 Bydgoszcz (Poland); Laboratory of Optoelectronic Materials (LOM), Department of Electronics of Ivan Franko, National University of Lviv, Gen. Tarnavskyj str., 107, 70017 Lviv (Ukraine); Gorbenko, V. [Laboratory of Optoelectronic Materials (LOM), Department of Electronics of Ivan Franko, National University of Lviv, Gen. Tarnavskyj str., 107, 70017 Lviv (Ukraine); Savchyn, V. [Laboratory of Optoelectronic Materials (LOM), Department of Electronics of Ivan Franko, National University of Lviv, Gen. Tarnavskyj str., 107, 70017 Lviv (Ukraine); Cukrovarnicka str., 10, 162 53 Prague (Czech Republic); Zorenko, T. [Laboratory of Optoelectronic Materials (LOM), Department of Electronics of Ivan Franko, National University of Lviv, Gen. Tarnavskyj str., 107, 70017 Lviv (Ukraine); Nikl, M.; Mares, J.A.; Beitlerova, A.; Jary, V. [Institute of Physics of Academy of Sciences of Czech Republic (Czech Republic)

    2013-09-15

    Absorption, cathodoluminescence, excitation spectra of photoluminescence (PL) and PL decay kinetics were studied at 300 K for the double doped with Bi{sup 3+}–Pr{sup 3+} and separately doped with Bi{sup 3+} and Pr{sup 3+} Lu{sub 3}Al{sub 5}O{sub 12} (LuAG) and Y{sub 3}Al{sub 5}O{sub 12} (YAG) single crystalline film (SCF) phosphors grown by the liquid phase epitaxy method. The emission bands in the UV range arising from the intrinsic radiative transitions of Bi{sup 3+} based centers, and emission bands in the visible range, related to the luminescence of excitons localized around Bi{sup 3+} based centers, were identified both in Bi–Pr and Bi-doped LuAG and YAG SCFs. The energy transfer processes from the host lattice simultaneously to Bi{sup 3+} and Pr{sup 3+} ions and from Bi{sup 3+} to Pr{sup 3+} ions were investigated. Competition between Pr{sup 3+} and Bi{sup 3+} ions in the energy transfer processes from the LuAG and YAG hosts was evidenced. The strong decrease of the intensity of Pr{sup 3+} luminescence both in LuAG:Pr and YAG:Pr SCFs phosphors, grown from Bi{sub 2}O{sub 3} flux, is observed due to the quenching influence of Bi{sup 3+} flux related impurity. Due to overlap of the UV emission band of Bi{sup 3+} centers with the f–d absorption bands of Pr{sup 3+} ions in the UV range and the luminescence of excitons localized around Bi ions with the f–f absorption bands of Pr{sup 3+} ions in the visible range, an effective energy transfer from Bi{sup 3+} ions to Pr{sup 3+} ions takes place in LuAG:Bi,Pr and YAG:Bi,Pr SCFs, resulting in the appearance of slower component in the decay kinetics of the Pr{sup 3+} d–f luminescence. -- Highlights: • Bi and Pr doped film phosphor grown by liquid phase epitaxy method. • Energy transfer from Bi{sup 3+} to Pr{sup 3+} ions. • Strong quenching of the Pr{sup 3+} luminescence by Bi{sup 3+} co-dopant.

  15. On Flat Objects of Finitely Accessible Categories

    Directory of Open Access Journals (Sweden)

    Septimiu Crivei

    2013-01-01

    Full Text Available Flat objects of a finitely accessible additive category are described in terms of some objects of the associated functor category of , called strongly flat functors. We study closure properties of the class of strongly flat functors, and we use them to deduce the known result that every object of a finitely accessible abelian category has a flat cover.

  16. Dual polarization flat plate antenna

    Science.gov (United States)

    Kelly, Kenneth C.

    Rectangular waveguides with radiating slots are used in groups to form planar array microwave antennas with large apertures and small depth. Such flat plate antennas are widely used on spacecraft and aircraft. Typically, flat plate antennas provide fixed linear polarization. The present paper describes a new flat plate antenna which produces two coincident beams that are distinguished by their orthogonal linear polarizations. The antenna has two ports, one for each of the coicident beams. Completely external to the antenna, connecting a simple network to those terminal ports enables the antenna to provide right circular polarization from one port and left from the other. A different external network enables the antenna to have arbitrarily adjustable polarizations.

  17. The Fallacies of Flatness: Thomas Friedman's "The World Is Flat"

    Science.gov (United States)

    Abowitz, Kathleen Knight; Roberts, Jay

    2007-01-01

    Thomas Friedman's best-selling "The World is Flat" has exerted much influence in the west by providing both an accessible analysis of globalization and its economic and social effects, and a powerful cultural metaphor for globalization. In this review, we more closely examine Friedman's notion of the social contract, the moral center of his…

  18. Nonlocal gravity: Conformally flat spacetimes

    CERN Document Server

    Bini, Donato

    2016-01-01

    The field equations of the recent nonlocal generalization of Einstein's theory of gravitation are presented in a form that is reminiscent of general relativity. The implications of the nonlocal field equations are studied in the case of conformally flat spacetimes. Even in this simple case, the field equations are intractable. Therefore, to gain insight into the nature of these equations, we investigate the structure of nonlocal gravity in two-dimensional spacetimes. While any smooth 2D spacetime is conformally flat and satisfies Einstein's field equations, only a subset containing either a Killing vector or a homothetic Killing vector can satisfy the field equations of nonlocal gravity.

  19. Liquid-gated interface superconductivity on an atomically flat film

    NARCIS (Netherlands)

    Ye, J. T.; Inoue, S.; Kobayashi, K.; Kasahara, Y.; Yuan, H. T.; Shimotani, H.; Iwasa, Y.

    2010-01-01

    Liquid/solid interfaces are attracting growing interest not only for applications in catalytic activities and energy storage(1,2), but also for their new electronic functions in electric double-layer transistors (EDLTs) exemplified by high-performance organic electronics(3-7), field-induced electron

  20. Wafer-Size and Single-Crystal MoSe2 Atomically Thin Films Grown on GaN Substrate for Light Emission and Harvesting.

    Science.gov (United States)

    Chen, Zuxin; Liu, Huiqiang; Chen, Xuechen; Chu, Guang; Chu, Sheng; Zhang, Hang

    2016-08-10

    Two-dimensional (2D) atomic-layered semiconductors are important for next-generation electronics and optoelectronics. Here, we designed the growth of an MoSe2 atomic layer on a lattice-matched GaN semiconductor substrate. The results demonstrated that the MoSe2 films were less than three atomic layers thick and were single crystalline of MoSe2 over the entire GaN substrate. The ultrathin MoSe2/GaN heterojunction diode demonstrated ∼850 nm light emission and could also be used in photovoltaic applications. PMID:27409977

  1. The complexity of flat origami

    Energy Technology Data Exchange (ETDEWEB)

    Bern, M. [Xerox, Palo Alto, CA (United States); Hayes, B. [ParcPlace-Digitalk, Inc., Sunnyvale, CA (United States)

    1996-12-31

    We study a basic problem in mathematical origami: determine if a given crease pattern can be folded to a flat origami. We show that assigning mountain and valley folds is NP-hard. We also show that determining a suitable overlap order for flaps is NP-hard, even assuming a valid mountain and valley assignment.

  2. Flat space physics from holography

    CERN Document Server

    Bousso, R

    2004-01-01

    We point out that aspects of quantum mechanics can be derived from the holographic principle, using only a perturbative limit of classical general relativity. In flat space, the covariant entropy bound reduces to the Bekenstein bound. The latter does not contain Newton's constant and cannot operate via gravitational backreaction. Instead, it is protected by - and in this sense, predicts - the Heisenberg uncertainty principle

  3. Crystal and local atomic structure of Co-doped MgFeBO_4 warwickites

    OpenAIRE

    Kazak, N. V.; Platunov, M. S.; Knyazev, Yu. V.; Ivanova, N. B.; Zubavichus, Y. V.; Veligzhanin, A. A.; Vasiliev, A. D.; Bezmaternykh, L. N.; Bayukov, O. A.; Arauzo, A.; Bartolomé, J.; Lamonova, K. V.; Ovchinnikov, S. G.

    2014-01-01

    Single crystalline MgFeBO_4, Mg_0.5Co_0.5FeBO_4 and CoFeBO_4 have been grown by the flux method. The samples have been characterized by X-ray spectral analysis, X-ray diffraction and X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra have been measured at the Fe andCoK-edges over a wide temperature range (6.5 - 300 K). The composition, the charge state and local environment of both Fe and Co atoms have b...

  4. Lu.sub.2./sub.SiO.sub.5./sub.:Ce and Y.sub.2./sub.SiO.sub.5./sub.:Ce single crystals and single crystalline film scintillators: comparisom of the luminescent and scintillation properties

    Czech Academy of Sciences Publication Activity Database

    Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Zorenko, T.; Grinyov, B.; Sidletskiy, O.; Fedorov, A.; Mareš, Jiří A.; Nikl, Martin; Kučera, M.

    2013-01-01

    Roč. 56, SEP (2013), s. 84-89. ISSN 1350-4487. [International Conference on Luminescent Detectors and Transformers of Ionizing Radiation 2012 /8./, LUMDETR 2012. Halle (Saale), 10.09.2012-14.09.2012] R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : Lu 2 SiO 5 :Ce * Y 2 SiO 2 * single crystalline film, * single crystal * luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.140, year: 2013

  5. Focal Rigidity of Flat Tori

    CERN Document Server

    Kwakkel, Ferry; Peixoto, Mauricio

    2011-01-01

    Given a closed Riemannian manifold (M, g), there is a partition \\Sigma_i of its tangent bundle TM called the focal decomposition. The sets \\Sigma_i are closely associated to focusing of geodesics of (M, g), i.e. to the situation where there are exactly i geodesic arcs of the same length joining points p and q in M. In this note, we study the topological structure of the focal decomposition of a closed Riemannian manifold and its relation with the metric structure of the manifold. Our main result is that the flat n-tori are focally rigid, in the sense that if two flat tori are focally equivalent, then the tori are isometric up to rescaling.

  6. 49 CFR 231.6 - Flat cars.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Flat cars. 231.6 Section 231.6 Transportation... TRANSPORTATION RAILROAD SAFETY APPLIANCE STANDARDS § 231.6 Flat cars. (Cars with sides 12 inches or less above the floor may be equipped the same as flat cars.) (a) Hand brakes—(1) Number. Same as specified...

  7. Flat panel display - Impurity doping technology for flat panel displays

    International Nuclear Information System (INIS)

    Features of the flat panel displays (FPDs) such as liquid crystal display (LCD) and organic light emitting diode (OLED) display, etc. using low temperature poly-Si (LTPS) thin film transistors (TFTs) are briefly reviewed comparing with other FPDs. The requirements for fabricating TFTs used for high performance FPDs and system on glass (SoG) are addressed. This paper focuses on the impurity doping technology, which is one of the key technologies together with crystallization by laser annealing, formation of high quality gate insulator and gate-insulator/poly-Si interface. The issues to be solved in impurity doping technology for state of the art and future TFTs are clarified

  8. Flat panel display - Impurity doping technology for flat panel displays

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Toshiharu [Advanced Technology Planning, Sumitomo Eaton Nova Corporation, SBS Tower 9F, 10-1, Yoga 4-chome, Setagaya-ku, 158-0097 Tokyo (Japan)]. E-mail: suzuki_tsh@senova.co.jp

    2005-08-01

    Features of the flat panel displays (FPDs) such as liquid crystal display (LCD) and organic light emitting diode (OLED) display, etc. using low temperature poly-Si (LTPS) thin film transistors (TFTs) are briefly reviewed comparing with other FPDs. The requirements for fabricating TFTs used for high performance FPDs and system on glass (SoG) are addressed. This paper focuses on the impurity doping technology, which is one of the key technologies together with crystallization by laser annealing, formation of high quality gate insulator and gate-insulator/poly-Si interface. The issues to be solved in impurity doping technology for state of the art and future TFTs are clarified.

  9. Defining Contact at the Atomic Scale

    OpenAIRE

    Cheng, Shengfeng; Robbins, Mark O.

    2010-01-01

    Molecular dynamics simulations are used to study different definitions of contact at the atomic scale. The roles of temperature, adhesive interactions and atomic structure are studied for simple geometries. An elastic, crystalline substrate contacts a rigid, atomically flat surface or a spherical tip. The rigid surface is formed from a commensurate or incommensurate crystal or an amorphous solid. Spherical tips are made by bending crystalline planes or removing material outside a sphere. In c...

  10. Radioactive waste package development at the Rocky Flats Plant

    International Nuclear Information System (INIS)

    Information is presented on some of the historical and current package developments for the plutonium-239 wastes generated at the Rocky Flats Plant. The two basic packages used for waste containment during transportation and storage are the steel drum and the plywood box. For steel drums, a discussion on a series of liners and liner characteristics designed to provide long package life is presented. This discussion includes data on the liner specifications, materials of construction, sealing techniques, seal strengths, and drop tests. For the plywood box, some experience and developments are described on the design, construction and drop testing of boxes coated with fiberglass reinforced plastic (FRP). Cost data and comparisons as appropriate for different drum liners and for the FRP coated plywood box are also included. The Rocky Flats facility is operated by Rockwell International, Atomics International Division, for the United States Energy Research and Development Administration (U.S. ERDA). (author)

  11. Engineering flat electronic bands in quasiperiodic and fractal loop geometries

    Science.gov (United States)

    Nandy, Atanu; Chakrabarti, Arunava

    2015-11-01

    Exact construction of one electron eigenstates with flat, non-dispersive bands, and localized over clusters of various sizes is reported for a class of quasi-one-dimensional looped networks. Quasiperiodic Fibonacci and Berker fractal geometries are embedded in the arms of the loop threaded by a uniform magnetic flux. We work out an analytical scheme to unravel the localized single particle states pinned at various atomic sites or over clusters of them. The magnetic field is varied to control, in a subtle way, the extent of localization and the location of the flat band states in energy space. In addition to this we show that an appropriate tuning of the field can lead to a re-entrant behavior of the effective mass of the electron in a band, with a periodic flip in its sign.

  12. Flat lens for seismic waves

    CERN Document Server

    Brule, Stephane; Guenneau, Sebastien

    2016-01-01

    A prerequisite for achieving seismic invisibility is to demonstrate the ability of civil engineers to control seismic waves with artificially structured soils. We carry out large-scale field tests with a structured soil made of a grid consisting of cylindrical and vertical holes in the ground and a low frequency artificial source (< 10 Hz). This allows the identification of a distribution of energy inside the grid, which can be interpreted as the consequence of an effective negative refraction index. Such a flat lens reminiscent of what Veselago and Pendry envisioned for light opens avenues in seismic metamaterials to counteract the most devastating components of seismic signals.

  13. Reflections on a flat wall

    International Nuclear Information System (INIS)

    This paper describes an investigation into whether estimates of attenuation in the flat sidewalls of the tunnel for the MC main ring can be based on a simple point-source/line-of-sight model. Having seen the limitations of such a model, an alternative is proposed where the main radiation source is not the initial object struck by the beam but the plane source provided by the first interactions of secondaries from the target in the shield-wall. This is shown to have a closer relation to reality than the point-source/line-of-sight model. (author)

  14. A flat laser array aperture

    Science.gov (United States)

    Papadakis, Stergios J.; Ricciardi, Gerald F.; Gross, Michael C.; Krill, Jerry A.

    2010-04-01

    We describe a design concept for a flat (or conformal) thin-plate laser phased-array aperture. The aperture consists of a substrate supporting a grid of single-mode optical waveguides fabricated from a linear electro-optic material. The waveguides are coupled to a single laser source or detector. An arrangement of electrodes provides for two-dimensional beam steering by controlling the phase of the light entering the grid. The electrodes can also be modulated to simultaneously provide atmospheric turbulence modulation for long-range free-space optical communication. An approach for fabrication is also outlined.

  15. Abrasion of flat rotating shapes

    OpenAIRE

    Roth, A.E.; Marques, C. M.; Durian, D. J.

    2010-01-01

    We report on the erosion of flat linoleum "pebbles" under steady rotation in a slurry of abrasive grit. To quantify shape as a function of time, we develop a general method in which the pebble is photographed from multiple angles with respect to the grid of pixels in a digital camera. This reduces digitization noise, and allows the local curvature of the contour to be computed with a controllable degree of uncertainty. Several shape descriptors are then employed to follow the evolution of dif...

  16. National construction, Denmark. Flat roofs

    Energy Technology Data Exchange (ETDEWEB)

    Rode, C.

    1995-04-01

    The Paris meeting of IEA Annex 24 (held in the spring of 1991) declared a set of typical building constructions, the Heat, Air and Moisture characteristics of which should be dealt with as part of the Annex work. Each type of construction was assigned to one or more countries as their National Construction, and it has been the responsibility of each country to prepare a report on what may be regarded as common knowledge in the country on the hygrothermal behaviour of their construction. This knowledge is in part due to experimental work carried out by research bodies in the countries, and due to experience form practice. This report has two main sections: Section 2 gives a general overview of the design of the most common variants of flat roofs and common knowledge reported for such roofs. Section 3 gives an account of research projects carried out in Denmark on flat roofs to analyze their hygrothermal performance. Whenever possible, an emphasis will be put on the hygrothermal consequences of thermally insulating such constructions. (EG) 19 refs.

  17. Atom Chips

    CERN Document Server

    Folman, R; Cassettari, D; Hessmo, B; Maier, T; Schmiedmayer, J; Folman, Ron; Krüger, Peter; Cassettari, Donatella; Hessmo, Björn; Maier, Thomas

    1999-01-01

    Atoms can be trapped and guided using nano-fabricated wires on surfaces, achieving the scales required by quantum information proposals. These Atom Chips form the basis for robust and widespread applications of cold atoms ranging from atom optics to fundamental questions in mesoscopic physics, and possibly quantum information systems.

  18. "Flat-Fish" Vacuum Chamber

    CERN Multimedia

    1978-01-01

    The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.

  19. Flat bunches in the LHC

    CERN Document Server

    Shaposhnikova, E; Baudrenghien, P; Mastoridis, T; Muller, J E; Papotti, G; Salvant, B; Timko, H; Bhat, C; Burov, A

    2014-01-01

    A high harmonic RF system which could serve multiple purposes was proposed for the LHC. Possible applications of the second harmonic RF system include beam stabilisation in the longitudinal plane in absence of wide-band longitudinal feedback and reduction of bunch peak line density. Apart from other useful features flat bunches are expected to produce less beam-induced heating below 1 GHz, the frequency region critical for some LHC equipment. The latter however can also be achieved by de-populating the bunch center. This was demonstrated during the dedicated machine development session in the LHC using RF phase modulation. In this paper the results of tests with single bunches and nominal LHC beams are presented and possible use of this technique in LHC operation is discussed.

  20. Flat laminated microbial mat communities

    Science.gov (United States)

    Franks, Jonathan; Stolz, John F.

    2009-10-01

    Flat laminated microbial mats are complex microbial ecosystems that inhabit a wide range of environments (e.g., caves, iron springs, thermal springs and pools, salt marshes, hypersaline ponds and lagoons, methane and petroleum seeps, sea mounts, deep sea vents, arctic dry valleys). Their community structure is defined by physical (e.g., light quantity and quality, temperature, density and pressure) and chemical (e.g., oxygen, oxidation/reduction potential, salinity, pH, available electron acceptors and donors, chemical species) parameters as well as species interactions. The main primary producers may be photoautotrophs (e.g., cyanobacteria, purple phototrophs, green phototrophs) or chemolithoautophs (e.g., colorless sulfur oxidizing bacteria). Anaerobic phototrophy may predominate in organic rich environments that support high rates of respiration. These communities are dynamic systems exhibiting both spatial and temporal heterogeneity. They are characterized by steep gradients with microenvironments on the submillimeter scale. Diel oscillations in the physical-chemical profile (e.g., oxygen, hydrogen sulfide, pH) and species distribution are typical for phototroph-dominated communities. Flat laminated microbial mats are often sites of robust biogeochemical cycling. In addition to well-established modes of metabolism for phototrophy (oxygenic and non-oxygenic), respiration (both aerobic and anaerobic), and fermentation, novel energetic pathways have been discovered (e.g., nitrate reduction couple to the oxidation of ammonia, sulfur, or arsenite). The application of culture-independent techniques (e.g., 16S rRNA clonal libraries, metagenomics), continue to expand our understanding of species composition and metabolic functions of these complex ecosystems.

  1. Representability of Hom Implies Flatness

    Indian Academy of Sciences (India)

    Nitin Nitsure

    2004-02-01

    Let be a projective scheme over a noetherian base scheme , and let $\\mathcal{F}$ be a coherent sheaf on . For any coherent sheaf $\\mathcal{E}$ on , consider the set-valued contravariant functor $\\hom_{(\\mathcal{E},\\mathcal{F})}$ on -schemes, defined by $\\hom_{(\\mathcal{E},\\mathcal{F})}(T)=\\mathrm{Hom}(\\mathcal{E}_T,\\mathcal{F}_T)$ where $\\mathcal{E}_T$ and $\\mathcal{F}_T$ are the pull-backs of $\\mathcal{E}$ and $\\mathcal{F}$ to $X_T=X×_s T$. A basic result of Grothendieck ([EGA], III 7.7.9) says that if $\\mathcal{F}$ is flat over then $\\hom_{(\\mathcal{E},\\mathcal{F})}$ is representable for all $\\mathcal{E}$. We prove the converse of the above, in fact, we show that if is a relatively ample line bundle on over such that the functor $\\hom_{(L^{-n},\\mathcal{F})}$ is representable for infinitely many positive integers , then $\\mathcal{F}$ is flat over . As a corollary, taking $X=S$, it follows that if $\\mathcal{F}$ is a coherent sheaf on then the functor $T\\mapsto H^0(T,\\mathcal{F}_T)$ on the category of -schemes is representable if and only if $\\mathcal{F}$ is locally free on . This answers a question posed by Angelo Vistoli. The techniques we use involve the proof of flattening stratification, together with the methods used in proving the author's earlier result (see [N1]) that the automorphism group functor of a coherent sheaf on is representable if and only if the sheaf is locally free.

  2. Gravitating cosmic strings with flat directions

    OpenAIRE

    Hartmann, Betti; Lopez-Eiguren, Asier; Sousa, Kepa; Urrestilla, Jon

    2012-01-01

    We study field theoretical models for cosmic strings with flat directions in curved space-time. More precisely, we consider minimal models with semilocal, axionic and tachyonic strings, respectively. In flat space-time, the string solutions of these models have a flat direction, i.e., a uniparametric family of configurations with the same energy exists which is associated to a zero mode. We prove that the zero mode survives coupling to gravity, and study the role of the flat direction when co...

  3. Flat-band engineering of mobility edges

    Science.gov (United States)

    Danieli, Carlo; Bodyfelt, Joshua D.; Flach, Sergej

    2015-06-01

    Properly modulated flat-band lattices have a divergent density of states at the flat-band energy. Quasiperiodic modulations are known to host a metal-insulator transition already in one space dimension. Their embedding into flat-band geometries consequently allows for a precise engineering and fine tuning of mobility edges. We obtain analytic expressions for singular mobility edges for two flat-band lattice examples. In particular, we engineer cases with arbitrarily small energy separations of mobility edge, zeroes, and divergencies.

  4. Flat conductor cable design, manufacture, and installation

    Science.gov (United States)

    Angele, W.; Hankins, J. D.

    1973-01-01

    Pertinent information for hardware selection, design, manufacture, and quality control necessary for flat conductor cable interconnecting harness application is presented. Comparisons are made between round wire cable and flat conductor cable. The flat conductor cable interconnecting harness systems show major cost, weight, and space savings, plus increased system performance and reliability. The design application section includes electrical characteristics, harness design and development, and a full treatise on EMC considerations. Manufacturing and quality control sections pertain primarily to the developed conductor-contact connector system and special flat conductor cable to round wire cable transitions.

  5. Production of annular flat-topped vortex beams

    Institute of Scientific and Technical Information of China (English)

    Jiannong Chen; Yongjiang Yu; Feifei Wang

    2011-01-01

    @@ A model of an annular flat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.%A model of an annular fiat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.

  6. Natural convection between flat parallel plates

    International Nuclear Information System (INIS)

    The rate of heat transfer between two flat parallel plates inclined at some angle to the horizone is of abvious important in performance of the flat plat collectors. A complete computer program have been made for calculating free convection heat transfer coefficient, h. Angle plays as an important parameter for determining Nusselt values for plate spacing more than 5mm.(Author)

  7. Radiation monitor training program at Rocky Flats

    International Nuclear Information System (INIS)

    The Rocky Flats Radiation Monitor Training Program is tailored to train new health physics personnel in the field of radiation monitoring. The purpose of the prescribed materials and media is to be consistent in training in all areas of Rocky Flats radiation monitoring job involvement

  8. Structural and magnetic properties of single-crystalline spinel systems ZnCr2-xAl xSe4 (x = 0.15 and 0.23)

    International Nuclear Information System (INIS)

    Single crystals of the spinel solid solutions ZnCr2-xAl xSe4 with x = 0.15 and 0.23 were grown and studied by X-ray diffraction and macroscopic magnetic measurements. The solubility of Al3+ ions in the parent compound ZnCr2Se4 is very limited and only weakly substituted single crystals can be obtained. The spinel structure is hardly modified by this admixture and regular cation distribution is preserved. Alike ZnCr2Se4, the two compounds investigated order antiferromagnetically at low temperatures. Both the Neel temperatures and the paramagnetic Curie temperatures are similar to that reported for the parent selenide. Also the effective magnetic moments are close to that of ZnCr2Se4 and compatible with trivalent Cr ions. In contrast, the saturation magnetic moments measured above the metamagnetic phase transitions in strong magnetic fields and calculated per one Cr atom, appear to be strongly affected by the Al-substitution, being rapidly suppressed with rising Al-content

  9. Atomic energy

    CERN Multimedia

    1996-01-01

    Interviews following the 1991 co-operation Agreement between the Department of Atomic Energy (DAE) of the Government of India and the European Organization for Nuclear Research (CERN) concerning the participation in the Large Hadron Collider Project (LHC) . With Chidambaram, R, Chairman, Atomic Energy Commission and Secretary, Department of Atomic Energy, Department of Atomic Energy (DAE) of the Government of India and Professor Llewellyn-Smith, Christopher H, Director-General, CERN.

  10. Atom chips

    CERN Document Server

    Reichel, Jakob

    2010-01-01

    This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.

  11. High pressure synthesis and characterization of single crystalline YBa2Cu4O8(Tc=80 K) and Y2Ba4Cu7O15±χ (14 K ≤ Tc ≤ 94 K)

    International Nuclear Information System (INIS)

    The merits of the high oxygen pressure synthesis of the YBaCuO oxides and the advantages of a two-chamber autoclave are briefly reviewed. The P-T-x and the flux P-T phase diagrams are presented for the first time. The P-T-x diagram shows the P-T cuts across the compositions 123, 123.5 and 124; the 123 is not stable in the low temperature region and the 123.5 must be cooled through the stability range of 124, with the corresponding implications. The flux P-T diagram shows the fields of crystallisation under high oxygen pressure of the above three HTc-phases. Crystallization experiments give some first results about the complex growth mechanism of 124 and 123.5, in which also the vapour phase seems to be important. A brief survey of the physical properties of the double chain compounds is also given: STM investigations show that micron range areas of as grown surfaces are atomically smooth with perfect singular steps with unit cell height. Although the Tc of the 124 crystals is 7-9 K lower than that of the ceramic (81 K) - probably due to traces of aluminum - the diamagnetic transition of single crystals is very steep (ΔT=2 K). Due to the thermodynamic stability of the double chains, 124 and 123.5 do not have a-b twins and, therefore, are ideal for measurements of anisotropy. Transport and optical properties show an anisotropy of 3-5. Electronic Raman scattering in single crystals of 124 shows the existence of two gaps, attributed to the chains and the plains. Also the critical fields Hc1 and Hc2 of 124 have been measured and found approx. 3 times lower than those of 123. This means that the coherence length is also longer in 124. (orig.)

  12. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  13. Atomic Physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  14. Atomic polarizabilities

    International Nuclear Information System (INIS)

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed

  15. Atom interferometry

    International Nuclear Information System (INIS)

    We will first present a development of the fundamental principles of atom interferometers. Next we will discuss a few of the various methods now available to split and recombine atomic De Broglie waves, with special emphasis on atom interferometers based on optical pulses. We will also be particularly concerned with high precision interferometers with long measurement times such those made with atomic fountains. The application of atom interferometry to the measurement of the acceleration due to gravity will be detailed. We will also develop the atom interferometry based on adiabatic transfer and we will apply it to the measurement of the photon recoil in the case of the Doppler shift of an atomic resonance caused by the momentum recoil from an absorbed photon. Finally the outlook of future developments will be given. (A.C.)

  16. Phase decomposition and ordering in Ni-11.3 at.% Ti studied with atom probe tomography.

    Science.gov (United States)

    Al-Kassab, T; Kompatscher, M; Kirchheim, R; Kostorz, G; Schönfeld, B

    2014-09-01

    The decomposition behavior of Ni-rich Ni-Ti was reassessed using Tomographic Atom Probe (TAP) and Laser Assisted Wide Angle Tomographic Atom Probe. Single crystalline specimens of Ni-11.3 at.% Ti were investigated, the states selected from the decomposition path were the metastable γ″ and γ' states introduced on the basis of small-angle neutron scattering (SANS) and the two-phase model for evaluation. The composition values of the precipitates in these states could not be confirmed by APT data as the interface of the ordered precipitates may not be neglected. The present results rather suggest to apply a three-phase model for the interpretation of SANS measurements, in which the width of the interface remains nearly unchanged and the L12 structure close to 3:1 stoichiometry is maintained in the core of the precipitates from the γ″ to the γ' state. PMID:24981213

  17. Phase decomposition and ordering in Ni-11.3 at.% Ti studied with atom probe tomography

    KAUST Repository

    Al-Kassab, Talaat

    2014-09-01

    The decomposition behavior of Ni-rich Ni-Ti was reassessed using Tomographic Atom Probe (TAP) and Laser Assisted Wide Angle Tomographic Atom Probe. Single crystalline specimens of Ni-11.3at.% Ti were investigated, the states selected from the decomposition path were the metastable γ″ and γ\\' states introduced on the basis of small-angle neutron scattering (SANS) and the two-phase model for evaluation. The composition values of the precipitates in these states could not be confirmed by APT data as the interface of the ordered precipitates may not be neglected. The present results rather suggest to apply a three-phase model for the interpretation of SANS measurements, in which the width of the interface remains nearly unchanged and the L12 structure close to 3:1 stoichiometry is maintained in the core of the precipitates from the γ″ to the γ\\' state. © 2014 Elsevier Ltd.

  18. Long-range Rocky Flats utilization study

    International Nuclear Information System (INIS)

    The purpose of this Study was to provide information concerning the Rocky Flats Plant and its operations that will be useful to the Nation's decision-makers in determining the long-range future of the Plant. This Study was conducted under the premise that national defense policy must be supported and, accordingly, the capabilities at Rocky Flats must be maintained there or at some other location(s). The Study, therefore, makes no attempt to speculate on how possible future changes in national defense policy might affect decisions regarding the utilization of Rocky Flats. Factors pertinent to decisions regarding Rocky Flats, which are included in the Study, are: physical condition of the Plant and its vulnerabilities to natural phenomena; risks associated with plutonium to Plant workers and the public posed by postulated natural phenomena and operational accidents; identification of alternative actions regarding the future use of the Rocky Flats Plant with associated costs and time scales; local socioeconomic impacts if Rocky Flats operations were relocated; and potential for other uses if Rocky Flats facilities were vacated. The results of the tasks performed in support of this Study are summarized in the context of these five factors

  19. Communication: Two types of flat-planes conditions in density functional theory

    Science.gov (United States)

    Yang, Xiaotian Derrick; Patel, Anand H. G.; Miranda-Quintana, Ramón Alain; Heidar-Zadeh, Farnaz; González-Espinoza, Cristina E.; Ayers, Paul W.

    2016-07-01

    Using results from atomic spectroscopy, we show that there are two types of flat-planes conditions. The first type of flat-planes condition occurs when the energy as a function of the number of electrons of each spin, Nα and Nβ, has a derivative discontinuity on a line segment where the number of electrons, Nα + Nβ, is an integer. The second type of flat-planes condition occurs when the energy has a derivative discontinuity on a line segment where the spin polarization, Nα - Nβ, is an integer, but does not have a discontinuity associated with an integer number of electrons. Type 2 flat planes are rare—we observed just 15 type 2 flat-planes conditions out of the 4884 cases we tested—but their mere existence has implications for the design of exchange-correlation energy density functionals. To facilitate the development of functionals that have the correct behavior with respect to both fractional number of electrons and fractional spin polarization, we present a dataset for the chromium atom and its ions that can be used to test new functionals.

  20. AdS/Ricci-flat correspondence

    International Nuclear Information System (INIS)

    We present a comprehensive analysis of the AdS/Ricci-flat correspondence, a map between a class of asymptotically locally AdS spacetimes and a class of Ricci-flat spacetimes. We provide a detailed derivation of the map, discuss a number of extensions and apply it to a number of important examples, such as AdS on a torus, AdS black branes and fluids/gravity metrics. In particular, the correspondence links the hydrodynamic regime of asymptotically flat black p-branes or the Rindler fluid with that of AdS. It implies that this class of Ricci-flat spacetimes inherits from AdS a generalized conformal symmetry and has a holographic structure. We initiate the discussion of holography by analyzing how the map acts on boundary conditions and holographic 2-point functions

  1. Fuzzy Neural Model for Flatness Pattern Recognition

    Institute of Scientific and Technical Information of China (English)

    JIA Chun-yu; SHAN Xiu-ying; LIU Hong-min; NIU Zhao-ping

    2008-01-01

    For the problems occurring in a least square method model,a fuzzy model,and a neural network model for flatness pattern recognition,a fuzzy neural network model for flatness pattern recognition with only three-input and three-output signals was proposed with Legendre orthodoxy polynomial as basic pattern,based on fuzzy logic expert experiential knowledge and genetic-BP hybrid optimization algorithm.The model not only had definite physical meanings in its inner nodes,but also had strong self-adaptability,anti-interference ability,high recognition precision,and high velocity,thereby meeting the demand of high-precision flatness control for cold strip mill and providing a convenient,practical,and novel method for flatness pattern recognition.

  2. AdS/Ricci-flat correspondence

    CERN Document Server

    Caldarelli, M M; Goutéraux, B; Skenderis, K

    2014-01-01

    We present a comprehensive analysis of the AdS/Ricci-flat correspondence, a map between a class of asymptotically locally AdS spacetimes and a class of Ricci-flat spacetimes. We provide a detailed derivation of the map, discuss a number of extensions and apply the map to a number of important examples, such as AdS on a torus, AdS black branes and fluids/gravity metrics. In particular, the map links the hydrodynamic regime of asymptotically flat black $p$-branes or the Rindler fluid with that of AdS. The map implies that this class of Ricci-flat spacetimes inherits from AdS a generalized conformal symmetry and has a holographic structure. We initiate the discussion of holography by analyzing how the map acts on boundary conditions and holographic 2-point functions.

  3. Flat-package DIP handling tool

    Science.gov (United States)

    Angelou, E.; Fraser, R.

    1977-01-01

    Device, using magnetic attraction, can facilitate handling of integrated-circuit flat packages and prevent contamination and bent leads. Tool lifts packages by their cases and releases them by operation of manual plunger.

  4. Schroedinger atom

    International Nuclear Information System (INIS)

    Features of an electrodynamical interpretation suggested by Schroedinger for the wave function are discribed. According to this conception electron charges are continuously distributed all over the volume of an atomic system. The proof is given that classical electrodynamics keeps its action inside atom. Schroedinger's atom has been shown to be the only model in which electrones do not lose their energy for emission when they move around nucleus. A significance of the distributed electron charge self-field is estimated. Practical applications of this conception have been noted including the new trend in quantum electrodynamics. Experimental and theoretical corroborations of the atom model with a continuous electron charge are adduced

  5. Atomic physics

    International Nuclear Information System (INIS)

    Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 23Po,2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 23Po level of helium-like krypton

  6. Post-Punching Behavior of Flat Slabs

    OpenAIRE

    Fernández Ruiz, Miguel; Mirzaei, Yaser; Muttoni, Aurelio

    2013-01-01

    Reinforced concrete flat slabs are a common structural system for cast-in-place concrete slabs. Failures in punching shear near the column regions are typically governing at ultimate. In case no punching shear or integrity reinforcement is placed, failures in punching develop normally in a brittle manner with almost no warning signs. Furthermore, the residual strength after punching is, in general, significantly lower than the punching load. Thus, punching of a single column of a flat slab ov...

  7. Flat Taxes and Effective Tax Planning

    OpenAIRE

    Calegari, Michael

    1998-01-01

    Stiglitz (1985) shows that income deferral opportunities and differentially taxed economic activities provide incentives for investors to engage in tax avoidance strategies. In this paper, I describe several tax avoidance strategies that can be used by taxpayers in a Hall-Rabushka flat tax system to reduce or eliminate their tax liabilities. Effective tax planning continues to be viable in a flat tax regime because the idealized environment envisioned by the proposal does not consider taxpaye...

  8. Loop Quantum Gravity and Asymptotically Flat Spaces

    OpenAIRE

    Arnsdorf, Matthias

    2000-01-01

    After motivating why the study of asymptotically flat spaces is important in loop quantum gravity, we review the extension of the standard framework of this theory to the asymptotically flat sector based on the GNS construction. In particular, we provide a general procedure for constructing new Hilbert spaces for loop quantum gravity on non-compact spatial manifolds. States in these Hilbert spaces can be interpreted as describing fluctuations around fiducial fixed backgrounds. When the backgr...

  9. Flat H Frangible Joint Evolution

    Science.gov (United States)

    Diegelman, Thomas E.; Hinkel, Todd J.; Benjamin, Andrew; Rochon, Brian V.; Brown, Christopher W.

    2016-01-01

    Space vehicle staging and separation events require pyrotechnic devices. They are single-use mechanisms that cannot be tested, nor can failure-tolerant performance be demonstrated in actual flight articles prior to flight use. This necessitates the implementation of a robust design and test approach coupled with a fully redundant, failure-tolerant explosive mechanism to ensure that the system functions even in the event of a single failure. Historically, NASA has followed the single failure-tolerant (SFT) design philosophy for all human-rated spacecraft, including the Space Shuttle Program. Following the end of this program, aerospace companies proposed building the next generation human-rated vehicles with off-the-shelf, non-redundant, zero-failure-tolerant (ZFT) separation systems. Currently, spacecraft and launch vehicle providers for both the Orion and Commercial Crew Programs (CCPs) plan to deviate from the heritage safety approach and NASA's SFT human rating requirements. Both programs' partners have base-lined ZFT frangible joints for vehicle staging and fairing separation. These joints are commercially available from pyrotechnic vendors. Non-human-rated missions have flown them numerous times. The joints are relatively easy to integrate structurally within the spacecraft. In addition, the separation event is debris free, and the resultant pyro shock is lower than that of other design solutions. It is, however, a serious deficiency to lack failure tolerance. When used for critical applications on human-rated vehicles, a single failure could potentially lead to loss of crew (LOC) or loss of mission (LOM)). The Engineering and Safety & Mission Assurance directorates within the NASA Johnson Space Center took action to address this safety issue by initiating a project to develop a fully redundant, SFT frangible joint design, known as the Flat H. Critical to the ability to retrofit on launch vehicles being developed, the SFT mechanisms must fit within the same

  10. Atomic physics

    CERN Document Server

    Born, Max

    1989-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  11. Dynamic and atomic-scale understanding of the twin thickness effect on dislocation nucleation and propagation activities by in situ bending of Ni nanowires

    International Nuclear Information System (INIS)

    Although their mechanical behavior has been extensively studied, the atomic-scale deformation mechanisms of metallic nanowires (NWs) with growth twins are not completely understood. Using our own atomic-scale and dynamic mechanical testing techniques, bending experiments were conducted on single-crystalline and twin-structural Ni NWs (D = ∼40 nm) using a high-resolution transmission electron microscope (HRTEM). Atomic-scale and time-resolved dislocation nucleation and propagation activities were captured in situ. A large number of in situ HRTEM observations indicated strong effects from the twin thickness (TT) on dislocation type and glide system. In thick twin lamella (TT > ∼12 nm) and single-crystalline NWs, the plasticity was controlled by full dislocation nucleation. For NWs with twin thicknesses of ∼9 nm < TT < ∼12 nm, full and partial dislocation nucleation occurred from the free surface, and the dislocations glided on multiple systems and interacted with each other during plastic deformation. For NWs with twin thicknesses of ∼6 nm < TT < ∼9 nm, partial dislocation nucleation from the free surface and the gliding of those dislocations on the plane that intersected the twin boundaries (TBs) were the dominant plasticity events. For the NWs with twin thicknesses of ∼1 nm < TT < ∼6 nm, the plasticity was accommodated by a partial dislocation nucleation process and glide parallel to the TBs. When TT < ∼1 nm, TB migration and detwinning processes resulting from partial dislocation nucleation and glide adjacent to the TBs were frequently observed

  12. Andean flat subduction maintained by slab tunneling

    Science.gov (United States)

    Schepers, Gerben; van Hinsbergen, Douwe; Kosters, Martha; Boschman, Lydian; McQuarrie, Nadine; Spakman, Wim

    2016-04-01

    In two segments below the Andean mountain belt, the Nazca Plate is currently subducting sub-horizontally below South America over a distance of 200-300 km before the plate bends into the mantle. Such flat slab segments have pronounced effects on orogenesis and magmatism and are widely believed to be caused by the downgoing plate resisting subduction due to its local positive buoyancy. In contrast, here we show that flat slabs primarily result from a local resistance against rollback rather than against subduction. From a kinematic reconstruction of the Andean fold-thrust belt we determine up to ~390 km of shortening since ~50 Ma. During this time the South American Plate moved ~1400 km westward relative to the mantle, thus forcing ~1000 km of trench retreat. Importantly, since the 11-12 Ma onset of flat slab formation, ~1000 km of Nazca Plate subduction occurred, much more than the flat slab lengths, which leads to our main finding that the flat slabs, while being initiated by arrival of buoyant material at the trench, are primarily maintained by locally impeded rollback. We suggest that dynamic support of flat subduction comes from the formation of slab tunnels below segments with the most buoyant material. These tunnels trap mantle material until tearing of the tunnel wall provides an escape route. Fast subduction of this tear is followed by a continuous slab and the process can recur during ongoing rollback of the 7000 km wide Nazca slab at segments with the most buoyant subducting material, explaining the regional and transient character of flat slabs. Our study highlights the importance of studying subduction dynamics in absolute plate motion context.

  13. Do intertidal flats ever reach equilibrium?

    Science.gov (United States)

    Maan, D. C.; Prooijen, B. C.; Wang, Z. B.; De Vriend, H. J.

    2015-11-01

    Various studies have identified a strong relation between the hydrodynamic forces and the equilibrium profile for intertidal flats. A thorough understanding of the interplay between the hydrodynamic forces and the morphology, however, concerns more than the equilibrium state alone. We study the basic processes and feedback mechanisms underlying the long-term behavior of the intertidal system, restricting ourselves to unvegetated intertidal flats that are controlled by cross-shore tidal currents and wind waves and applying a 1-D cross-shore morphodynamic model. The results indicate that by an adjustment of the profile slope and shape, an initial imbalance between deposition and erosion is minimized within a few decades. What follows is a state of long-term seaward progradation or landward retreat of the intertidal flat, in which the cross-shore profile shape is largely maintained and the imbalance between deposition and erosion is not further reduced. These long-term trends can be explained by positive feedbacks from the morphology onto the hydrodynamic forces over the flat: initial accretion (erosion) decreases (increases) the shear stresses over the flat, which induces further accretion (erosion). This implies that a static equilibrium state cannot exist; the flat either builds out or retreats. The modeled behavior is in accordance with observations in the Yangtze Estuary. To treat these unbalanced systems with a one-dimensional numerical model, we propose a moving (Lagrangian) framework in which a stable cross-sectional shape and progradation speed can be derived for growing tidal flats, as a function of the wave climate and the sediment concentration in deeper water.

  14. Downsizing of single crystalline high aspect ratio tungsten nanowires

    International Nuclear Information System (INIS)

    Directional solidification of eutectic NiAl-W alloys offers an intuitive method to produce tungsten nanowires. Through the use of two different methods, the well-established Bridgman method and a newer type floating zone method, the direct influence of process parameters, like the withdrawal rate and the temperature gradient, onto the sample microstructure were studied. The sharp temperature gradient, built up using a four mirror system focusing the light emitted by halogen lamps inside the optical floating zone furnace allows producing nanowires with a diameter as small as 75 nm. Differences in the solid/liquid interface morphology depending on the solidification method used are discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Planar-integrated single-crystalline perovskite photodetectors

    KAUST Repository

    Saidaminov, Makhsud I.

    2015-11-09

    Hybrid perovskites are promising semiconductors for optoelectronic applications. However, they suffer from morphological disorder that limits their optoelectronic properties and, ultimately, device performance. Recently, perovskite single crystals have been shown to overcome this problem and exhibit impressive improvements: low trap density, low intrinsic carrier concentration, high mobility, and long diffusion length that outperform perovskite-based thin films. These characteristics make the material ideal for realizing photodetection that is simultaneously fast and sensitive; unfortunately, these macroscopic single crystals cannot be grown on a planar substrate, curtailing their potential for optoelectronic integration. Here we produce large-area planar-integrated films made up of large perovskite single crystals. These crystalline films exhibit mobility and diffusion length comparable with those of single crystals. Using this technique, we produced a high-performance light detector showing high gain (above 104 electrons per photon) and high gain-bandwidth product (above 108 Hz) relative to other perovskite-based optical sensors.

  16. Magnetic properties of single crystalline NpAs-NpSe

    Energy Technology Data Exchange (ETDEWEB)

    Mattenberger, K.; Vogt, O. (Lab. fuer Festkoerperphysik, ETH, Zuerich (Switzerland)); Rebizant, J.; Spirlet, J.C. (CEC, JRC, European Inst. for Transuranium Elements, Karlsruhe (Germany)); Bourdarot, F.; Burlet, P.; Rossat-Mignod, J.; Bouillet, M.N.; Blaise, A.; Sanchez, J.P. (CEN Grenoble, DRFM/SPSMSMDN 85X, 38 (France))

    1992-02-01

    The antiferromagnetic 3k-structure of NpAs transformes to a ferrimagnetic one in magnetic fields <60 kOe. The magnetic moment of the Np ion as determined by neutrons is 2.5 {mu}{sub B}. NpSe becomes antiferromagnetic below 38 K with a not yet resolved magnetic structure. The moment is only 1.35 {mu}{sub B}. In samples of NpAs mixed with 5, 10 and 15% NpSe we observed ferrimagnetic structures. The structure of the 5% sample was determined using neutrons and is described in detail. Admixture of NpSe increases the ferromagnetic exchange forces and reduces the ionic magnetic moment. The moment reduction is clearly evidenced by Moessbauer experiments. The exchange forces are anisotropic. Antiferromagnetic exchange favours the <100> direction, ferromagnetic exchange aligns the spins along <111>. (orig.).

  17. Downsizing of single crystalline high aspect ratio tungsten nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Milenkovic, Srdjan [IMDEA Materials Institute, Eric Kandel 2, 28906, Getafe (Spain); Drensler, Stefanie [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenberger Str. 69, 4040, Linz (Austria); Hassel, Achim Walter [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenberger Str. 69, 4040, Linz (Austria); Christian Doppler Laboratory for Combinatorial Oxide Chemistry, Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, Altenberger Str. 69, 4040, Linz (Austria)

    2015-06-15

    Directional solidification of eutectic NiAl-W alloys offers an intuitive method to produce tungsten nanowires. Through the use of two different methods, the well-established Bridgman method and a newer type floating zone method, the direct influence of process parameters, like the withdrawal rate and the temperature gradient, onto the sample microstructure were studied. The sharp temperature gradient, built up using a four mirror system focusing the light emitted by halogen lamps inside the optical floating zone furnace allows producing nanowires with a diameter as small as 75 nm. Differences in the solid/liquid interface morphology depending on the solidification method used are discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Sharp and Bright Photoluminescence Emission of Single Crystalline Diacetylene Nanoparticles

    CERN Document Server

    Kima, Seokho; Kima, Hyeong Tae; Cuic, Chunzhi; Park, Dong Hyuk

    2016-01-01

    Amorphous nanoparticles (NPs) of diacetylene (DA) molecules were prepared by using a reprecipitation method. After crystallization through solvent-vapor annealing process, the highly crystalline DA NPs show different structural and optical characteristics compared with the amorphous DA NPs. The single crystal structure of DA NPs was confirmed by high-resolution transmission electron microscopy (HR-TEM) and wide angle X-ray scattering (WAXS). The luminescence color and photoluminescence (PL) characteristics of the DA NPs were measured using color charge-coupled device (CCD) images and high-resolution laser confocal microscope (LCM). The crystalline DA NPs emit bright green light emission compared with amorphous DA NPs and the main PL peak of the crystalline DA NPs exhibits relative narrow and blue shift phenomena due to enhanced interaction between DA molecular in the nano-size crystal structure.

  19. Magnetic properties of single crystalline NpAs-NpSe

    International Nuclear Information System (INIS)

    The antiferromagnetic 3k-structure of NpAs transformes to a ferrimagnetic one in magnetic fields B. NpSe becomes antiferromagnetic below 38 K with a not yet resolved magnetic structure. The moment is only 1.35 μB. In samples of NpAs mixed with 5, 10 and 15% NpSe we observed ferrimagnetic structures. The structure of the 5% sample was determined using neutrons and is described in detail. Admixture of NpSe increases the ferromagnetic exchange forces and reduces the ionic magnetic moment. The moment reduction is clearly evidenced by Moessbauer experiments. The exchange forces are anisotropic. Antiferromagnetic exchange favours the direction, ferromagnetic exchange aligns the spins along . (orig.)

  20. Inorganic single crystalline fibers for dual-readout calorimetry

    CERN Document Server

    Pauwels, Kristof; Lecoq, Paul

    This thesis focuses on the improvement of the energy resolution of hadron calorimeters. The approach is based on dual-readout, which consists in the simultaneous detection of both scintillation and Cherenkov light. The comparison of these two signals allows a compensation of the energy fluctuations, which are inherent to the detection of hadronic showers. Lutetium aluminium garnets (LuAG), which are efficient scintillators when activated with rare-earth dopants (i.e. Cerium), can also act as Cherenkov radiators when undoped. Both undoped and doped crystals can then be assembled to build an efficient dual-readout calorimeter. With the objective to investigate the feasibility of this concept, the effects of the doping concentration and the use of various co-dopant on the light output and the timing properties of LuAG were studied. The growth method was demonstrated to induce significant differences in the nature and concentration of structural defects. The optimum geometry, which is based on single-crystals sha...

  1. The influence of instrumental parameters on the adhesion force in a flat-on-flat contact geometry

    Science.gov (United States)

    Çolak, Arzu; Wormeester, Herbert; Zandvliet, Harold J. W.; Poelsema, Bene

    2014-07-01

    Atomic force microscopy (AFM) has been used to measure the adhesion force between a flat Si(0 0 1) wafer and a micrometer sized flat silicon AFM tip. Force-distance curves have been recorded at different setpoints in order to elucidate their individual effect on the derived adhesion force. No dependence of the derived adhesion force on the applied load has been detected, making sure that no plastic changes in the morphology of either tip and/or sample occur. Other setpoints as the residence time of the tip at the substrate, the relative humidity, the size of the tip and the retraction velocity of the tip have been varied systematically. We have found that the adhesion force depends strongly on the velocity of the z-piezo and the tip size while, at least within the 0.5-41 s time window, the residence time does not have any measurable effect on the adhesion force. The time scale of the retraction varies between 0.2 and 25 s. The increase of the adhesion force with increasing retraction speed is ascribed to the viscous force. Finally, the adhesion force increases with increasing relative humidity.

  2. The influence of instrumental parameters on the adhesion force in a flat-on-flat contact geometry

    Energy Technology Data Exchange (ETDEWEB)

    Çolak, Arzu; Wormeester, Herbert, E-mail: h.wormeester@utwente.nl; Zandvliet, Harold J.W.; Poelsema, Bene

    2014-07-01

    Atomic force microscopy (AFM) has been used to measure the adhesion force between a flat Si(0 0 1) wafer and a micrometer sized flat silicon AFM tip. Force–distance curves have been recorded at different setpoints in order to elucidate their individual effect on the derived adhesion force. No dependence of the derived adhesion force on the applied load has been detected, making sure that no plastic changes in the morphology of either tip and/or sample occur. Other setpoints as the residence time of the tip at the substrate, the relative humidity, the size of the tip and the retraction velocity of the tip have been varied systematically. We have found that the adhesion force depends strongly on the velocity of the z-piezo and the tip size while, at least within the 0.5–41 s time window, the residence time does not have any measurable effect on the adhesion force. The time scale of the retraction varies between 0.2 and 25 s. The increase of the adhesion force with increasing retraction speed is ascribed to the viscous force. Finally, the adhesion force increases with increasing relative humidity.

  3. Aspects of warm-flat directions

    CERN Document Server

    Matsuda, Tomohiro

    2009-01-01

    We consider the evolution of the flat direction when there is a significant dissipation of the kinetic energy. The field may obtain Hubble-scale mass, but a slow-roll is possible due to the damping caused by the dissipation. Besides the damping effect, radiation may be created continuously by the dissipation and may enhance the fluctuations of the field. These effects may alter the usual cosmological scenarios associated with the flat direction. An example is the Affleck-Dine mechanism in which the dissipation may create significant (both qualitative and quantitative) discrepancies between the cold and the warm scenarios. We discuss several mechanisms of generating curvature perturbations that can be related to the warm-flat direction.

  4. Intermittent tracking of flat plate collectors

    International Nuclear Information System (INIS)

    A theoretical analysis of different intervals of intermittent two-axis tracking of the sun, on the amount of annual energy received by flat-plate collectors, has been carried out. The analysis was done for Ipoh, a city near the university at a latitude of 40 34 North in Malaysia. For the analysis, a computer program was developed to calculate the solar insulation according to the interval settings, considering ASHRAE Standard Sky assumption. Both direct and diffused components of solar radiation have been considered. The tracking system was targeted for flat plate collectors where the degree of tracking accuracy would be much lower Hence, the tracking mechanism will be much simpler and lower in costs. Results showed that by a 3-hour intermittent tracking, a flat-plate collector could get as much as 35% more annual energy than a fixed one. The 3-hour interval tracking greatly simplifies the gear mechanism from the motor to the solar collector. (Author)

  5. Compton detector with flat energy response

    International Nuclear Information System (INIS)

    The work focuses on the study of vacuum Compton detector (VCD) with flat energy response. The proposed VCD adopts a compensation design of' the emitter, i. e. a superimposition of materials of varied thicknesses, and is optimized with Monte Carlo method. The optimally designed VCD consists of an emitter with the superimposition of 0.01, 1 mm-thick Au, a 3 mm-thick Fe front window and a 3 mm-thick Pb shielding. Its non-flatness of energy response to gamma-ray is less than 10.7% over 0.4-7.0 MeV energy zone. The flatness of energy response to gamma ray of this VCD is more excellent than current gamma detectors'. (authors)

  6. The flat phase of quantum polymerized membranes

    CERN Document Server

    Coquand, O

    2016-01-01

    We investigate the flat phase of quantum polymerized phantom membranes by means of a nonperturbative renormalization group approach. We first implement this formalism for general quantum polymerized membranes and derive the flow equations that encompass both quantum and thermal fluctuations. We then deduce and analyze the flow equations relevant to study the flat phase and discuss their salient features : quantum to classical crossover and, in each of these regimes, strong to weak coupling crossover. We finally illustrate these features in the context of free standing graphene physics.

  7. Scalar Curvature and Intrinsic Flat Convergence

    CERN Document Server

    Sormani, Christina

    2016-01-01

    Herein we present open problems and survey examples and theorems concerning sequences of Riemannian manifolds with uniform lower bounds on scalar curvature and their limit spaces. Examples of Gromov and of Ilmanen which naturally ought to have certain limit spaces do not converge with respect to smooth or Gromov-Hausdorff convergence. Thus we focus here on the notion of Intrinsic Flat convergence, developed jointly with Wenger. This notion has been applied successfully to study sequences that arise in General Relativity. Gromov has suggested it should be applied in other settings as well. We first review intrinsic flat convergence, its properties, and its compactness theorems, before presenting the applications and the open problems.

  8. Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films

    Science.gov (United States)

    Ghasemi, A.; Kepaptsoglou, D.; Collins-McIntyre, L. J.; Ramasse, Q.; Hesjedal, T.; Lazarov, V. K.

    2016-05-01

    We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film.

  9. Atomic secrecy

    International Nuclear Information System (INIS)

    An article, The H-Bomb Secret: How We Got It, Why We're Telling It, by Howard Morland was to be published in The Progressive magazine in February, 1979. The government, after learning of the author's and the editors' intention to publish the article and failing to persuade them to voluntarily delete about 20% of the text and all of the diagrams showing how an H-bomb works, requested a court injunction against publication. Acting under the Atomic Energy Act of 1954, US District Court Judge Robert W. Warren granted the government's request on March 26. Events dealing with the case are discussed in this publication. Section 1, Progressive Hydrogen Bomb Case, is discussed under the following: Court Order Blocking Magazine Report; Origins of the Howard Morland Article; Author's Motives, Defense of Publication; and Government Arguments Against Disclosure. Section 2, Access to Atomic Data Since 1939, contains information on need for secrecy during World War II; 1946 Atomic Energy Act and its effects; Soviet A-Bomb and the US H-Bomb; and consequences of 1954 Atomic Energy Act. Section 3, Disputed Need for Atomic Secrecy, contains papers entitled: Lack of Studies on H-Bomb Proliferation; Administration's Position on H-Bombs; and National Security Needs vs Free Press

  10. MSSM flat direction as a curvaton

    CERN Document Server

    Enqvist, Kari; Kasuya, S; Mazumdar, A; Enqvist, Kari; Jokinen, Asko; Kasuya, Shinta; Mazumdar, Anupam

    2003-01-01

    We study in detail the possibility that the flat directions of the Minimal Supersymmetric Standard Model (MSSM) could act as a curvaton and generate the observed adiabatic density perturbations. For that the flat direction energy density has to dominate the Universe at the time when it decays. We point out that this is not possible if the inflaton decays into MSSM degrees of freedom. If the inflaton is completely in the hidden sector, its decay products do not couple to the flat direction, and the flat direction curvaton can dominate the energy density. This requires the absence of a Hubble-induced mass for the curvaton, e.g. by virtue of the Heisenberg symmetry. In the case of hidden radiation, $n=9$ is the only admissible direction; for other hidden equations of state, directions with lower $n$ may also dominate. We show that the MSSM curvaton is further constrained severely by the damping of the fluctuations, and as an example, demonstrate that in no-scale supergravity it would fragment into $Q$ balls rath...

  11. Remediation of the Maxey Flats Site

    International Nuclear Information System (INIS)

    This report describes issues associated with remedial action of Maxey Flats, a low-level radioactive waste disposal site from 1963-1977, located in Fleming County, Kentucky. Present remedial action alternatives being considered are discussed along with emergency plans, ground water monitoring plans, and budgets

  12. Design scenarios for flat panel photobioreactors

    NARCIS (Netherlands)

    Slegers, P.M.; Wijffels, R.H.; Straten, van G.; Boxtel, van A.J.B.

    2011-01-01

    Evaluation of the potential of algae production for biofuel and other products at various locations throughout the world requires assessment of algae productivity under varying light conditions and different reactor layouts. A model was developed to predict algae biomass production in flat panel pho

  13. Promoting Employability in a "Flat" World

    Science.gov (United States)

    Parker, Polly

    2008-01-01

    T. L. Friedman (2005) described a "flat" world platform where competition and collaboration take place in real time among people all over the planet. Implications exist for people to assume responsibility for managing their own careers and ensuring their own security in a global economy. This article addresses those challenges from both the…

  14. Vortices in theories with flat directions

    NARCIS (Netherlands)

    Achucarro, A; Davis, AC; Pickles, M; Urrestilla, J

    2002-01-01

    In theories with flat directions containing vortices, such as supersymmetric QED, there is a vacuum selection effect in the allowed asymptotic configurations. We explain the role played by gauge fields in this effect and give a simple criterion for determining what vacua will be chosen, namely, thos

  15. 40 CFR 230.42 - Mud flats.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Mud flats. 230.42 Section 230.42 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) OCEAN DUMPING SECTION 404(b)(1) GUIDELINES FOR SPECIFICATION OF DISPOSAL SITES FOR DREDGED OR FILL MATERIAL Potential Impacts on...

  16. Asymptotically flat and regular Cauchy data

    CERN Document Server

    Dain, S

    2002-01-01

    I describe the construction of a large class of asymptotically flat initial data with non-vanishing mass and angular momentum for which the metric and the extrinsic curvature have asymptotic expansions at space-like infinity in terms of powers of a radial coordinate. I emphasize the motivations and the main ideas behind the proofs.

  17. 8. Asymptotically Flat and Regular Cauchy Data

    Science.gov (United States)

    Dain, Sergio

    I describe the construction of a large class of asymptotically flat initial data with non-vanishing mass and angular momentum for which the metric and the extrinsic curvature have asymptotic expansions at space-like infinity in terms of powers of a radial coordinate. I emphasize the motivations and the main ideas behind the proofs.

  18. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  19. Atoms as Qed bound atoms

    International Nuclear Information System (INIS)

    The relevance of Quantum Electrodynamics (Qed) in contemporary atomic structure theory is reviewed. Recent experimental advances allow both the production of heavy ions of high charge as well as the measurement of atomic properties with a precision never achieved before. The description of heavy atoms with few electrons via the successive incorporation of one, two, etcetera photons in a rigorous manner and within the bound state Furry representation of Qed is technically feasible. For many-electron atoms the many-body (correlation) effects are very important and it is practically impossible to evaluate all the relevant Feynman diagrams to the required accuracy. Thus, it is necessary to develop a theoretical scheme in which the radiative and nonradiative effects are taken into account in an effective way making emphasis in electronic correlation. Preserving gauge invariance, and avoiding both continuum dissolution and variational collapse are basic problems that must be solved when using effective potential methods and finite-basis representations of them. In this context, we shall discuss advances and problems in the description of atoms as Qed bound states. (Author)

  20. Flat-on-flat, nonconstrained, compression molded polyethylene total knee replacement.

    Science.gov (United States)

    Ritter, M A; Worland, R; Saliski, J; Helphenstine, J V; Edmondson, K L; Keating, E M; Faris, P M; Meding, J B

    1995-12-01

    Flat-on-flat, posterior cruciate ligament-sparing total knee prostheses recently have shown problems of wear, loosening, and multiple design changes. Two thousand one Anatomical Graduated Components total knee arthroplasties with compression molded, nonmodular polyethylene tibial components were done between 1983 and 1991 at 3 institutions. All knees were evaluated clinically and radiographically every 2 to 3 years; 71 knees were seen in followup > 10 years. There were 8 failures secondary to revision (5 tibial failures; 2 secondary to metalosis from patellar polyethylene dissociation; and 3 femoral failures) resulting in a 98% survival rate at 10 years. The tibial design was flat-on-flat with a compression molded polyethylene that the authors believe is the primary reason for its success. PMID:7497689

  1. Efficient flat metasurface lens for terahertz imaging.

    Science.gov (United States)

    Yang, Quanlong; Gu, Jianqiang; Wang, Dongyang; Zhang, Xueqian; Tian, Zhen; Ouyang, Chunmei; Singh, Ranjan; Han, Jiaguang; Zhang, Weili

    2014-10-20

    Metamaterials offer exciting opportunities that enable precise control of amplitude, polarization and phase of the light beam at a subwavelength scale. A gradient metasurface consists of a class of anisotropic subwavelength metamaterial resonators that offer abrupt amplitude and phase changes, thus enabling new applications in optical device design such as ultrathin flat lenses. We propose a highly efficient gradient metasurface lens based on a metal-dielectric-metal structure that operates in the terahertz regime. The proposed structure consists of slotted metallic resonator arrays on two sides of a thin dielectric spacer. By varying the geometrical parameters, the metasurface lens efficiently manipulates the spatial distribution of the terahertz field and focuses the beam to a spot size on the order of a wavelength. The proposed flat metasurface lens design is polarization insensitive and works efficiently even at wide angles of incidence. PMID:25401626

  2. Modelling Flat Spring performance using FEA

    International Nuclear Information System (INIS)

    This paper reports how the stiffness of a Flat Spring can be predicted using nonlinear Finite Element Analysis (FEA). The analysis of a Flat Spring is a nonlinear problem involving contact mechanics, geometric nonlinearity and material property nonlinearity. Research has been focused on improving the accuracy of the model by identifying and exploring the significant assumptions contributing to errors. This paper presents results from some of the models developed using FEA software. The validation process is shown to identify where improvements can be made to the model assumptions to increase the accuracy of prediction. The goal is to achieve an accuracy level of ±10 % as the intention is to replace practical testing with FEA modelling, thereby reducing the product development time and cost. Results from the FEA models are compared with experimental results to validate the accuracy.

  3. Towards a flat 45%-efficient concentrator module

    Energy Technology Data Exchange (ETDEWEB)

    Mohedano, Rubén, E-mail: rmohedano@lpi-europe.com; Hernandez, Maikel; Vilaplana, Juan; Chaves, Julio; Sorgato, S.; Falicoff, Waqidi [LPI, Altadena, CA, USA and Madrid (Spain); Miñano, Juan C.; Benitez, Pablo [LPI, Altadena, CA, USA and Madrid (Spain); Universidad Politécnica de Madrid (UPM), Campus de Montegancedo, Madrid (Spain)

    2015-09-28

    The so-called CCS{sup 4}FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations.

  4. Towards a flat 45%-efficient concentrator module

    Science.gov (United States)

    Mohedano, Rubén; Hernandez, Maikel; Vilaplana, Juan; Chaves, Julio; Miñano, Juan C.; Benitez, Pablo; Sorgato, S.; Falicoff, Waqidi

    2015-09-01

    The so-called CCS4FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations.

  5. Standard specification for silvered flat glass mirror

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This specification covers the requirements for silvered flat glass mirrors of rectangular shape supplied as cut sizes, stock sheets or as lehr ends and to which no further processing (such as edgework or other fabrication) has been done. 1.2 This specification covers the quality requirements of silvered annealed monolithic clear and tinted flat glass mirrors up to 6 mm (¼ in.) thick. The mirrors are intended to be used indoors for mirror glazing, for components of decorative accessories or for similar uses. 1.3 This specification does not address safety glazing materials nor requirements for mirror applications. Consult model building codes and other applicable standards for safety glazing applications. 1.4 Mirrors covered in this specification are not intended for use in environments where high humidity or airborne corrosion promoters, or both, are consistently present (such as swimming pool areas, ocean-going vessels, chemical laboratories and other corrosive environments). 1.5 The dimensional val...

  6. History of Rocky Flats waste streams

    International Nuclear Information System (INIS)

    An analysis of the waste streams at Rocky Flats was done to provide information for the Waste Certification program. This program has involved studying the types and amounts of retrievable transuranic (TRU) waste from Rocky Flats that is stored at the Idaho National Engineering Laboratory (INEL). The information can be used to estimate the types and amounts of waste that will need to be permanently stored in the Waste Isolation Pilot Plant (WIPP). The study covered mostly the eight-year period from June 1971 to June 1979. The types, amounts, and plutonium content of TRU waste and the areas or operations responsible for generating the waste are summarized in this waste stream history report. From the period studied, a total of 24,546,153 lbs of waste containing 211,148 g of plutonium currently occupies 709,497 cu ft of storage space at INEL

  7. Flat-spectrum, variable radio sources

    International Nuclear Information System (INIS)

    The general behavior of flat-spectrum (compact) radio sources is examined in terms of adiabatic-jet models. Two puzzling properties - namely, (1) the broad, rather flat spectrum (over a large range of radio frequencies) and (2) the relatively slow decay of burst amplitude (with decreasing radio frequency) - are explained. Acceptable models are characterized by the following: (1) a nearly conical, adiabatic jet, with conserved magnetic flux transverse to the axis of the jet; (2) prolonged injection (for which the duration of an event exceeds the apparent transit time scale); and (3) a transparent spectral index which is not too steep. It is suggested that the acceleration mechanism in the core of compact jets may differ substantially from that far from the core, producing a flatter electron number index s = 1.4-2.6. 42 references

  8. Gorenstein flatness and injectivity over Gorenstein rings

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Let R be a Gorenstein ring.We prove that if I is an ideal of R such that R/I is a semi-simple ring,then the Gorenstein flat dimension of R/I as a right R-module and the Gorenstein injective dimension of R/I as a left R-module are identical.In addition,we prove that if R→S is a homomorphism of rings and SE is an injective cogenerator for the category of left S-modules,then the Gorenstein flat dimension of S as a right R-module and the Gorenstein injective dimension of E as a left R-module are identical.We also give some applications of these results.

  9. Improving the durability of flat roof constructions

    DEFF Research Database (Denmark)

    Rudbeck, Claus Christian; Svendsen, Sv Aa Højgaard

    Flat roof constructions are mainly used on commercial, institutional and industrial buildings, where insulation is placed on top of the load-bearing deck and then covered with a roof membrane. Through time, there is a risk that the membrane will allow water passage as holes might form due to...... there is no easy method of drying it. To be able to dry the insulation, and thereby regain the functional requirements of the roofing system, two new solutions for insulating flat roofs with existing materials are proposed for high density mineral wool and expanded polystyrene. Monitoring equipment are......, they have a longer life span reducing the overall cost. Furthermore systems, where moisture can be removed, offer a high probability that the thermal conductivity remains at its designed value through the entire life of the roofing system. If the roofing membrane should fail, the insulation can be...

  10. Towards a flat 45%-efficient concentrator module

    International Nuclear Information System (INIS)

    The so-called CCS4FK is an ultra-flat photovoltaic system of high concentration and high efficiency, with potential to convert, ideally, the equivalent of a 45% of direct solar radiation into electricity by optimizing the usage of sun spectrum and by collecting part of the diffuse radiation, as a flat plate does. LPI has recently finished a design based on this concept and is now developing a prototype based on this technology, thanks to the support of FUNDACION REPSOL-Fondo de Emprendedores, which promotes entrepreneur projects in different areas linked to energy. This works shows some details of the actual design and preliminary potential performance expected, according to accurate spectral simulations

  11. Flat roof integration. CPT solar (AET IV)

    Energy Technology Data Exchange (ETDEWEB)

    Chianese, D.; Pola, I.; Bernasconi, A.; Bura, E.; Cereghetti, N.; Realini, A.; Pasinelli, P.; Rioggi, S.

    2007-11-15

    This illustrated final report for the Swiss Federal Office of Energy (SFOE) takes a look at a 15.4 kWp solar power installation in Trevano, Switzerland, that features flexible amorphous silicon triple-junction modules, mounted nearly horizontally and directly laminated to flexible polyolefin membranes that form the covering of a flat roof. The main objective of this study was to verify in which order of magnitude the better thermal behaviour of amorphous silicon cells can compensate for losses due to the quasi-horizontal roof integration (lower irradiation and higher reflection), and thus be competitive in the flat roof construction and refurbishment markets. The modules used and their characteristics are described. Performance, temperature levels and energy-production are reviewed for the panels of the installation. The performance of the inverter used is also reviewed. Data on temperatures and production are presented in graphical form and optical losses are examined.

  12. Improving the durability of flat roof constructions

    DEFF Research Database (Denmark)

    Rudbeck, Claus Christian; Svendsen, Sv Aa Højgaard

    there is no easy method of drying it. To be able to dry the insulation, and thereby regain the functional requirements of the roofing system, two new solutions for insulating flat roofs with existing materials are proposed for high density mineral wool and expanded polystyrene. Monitoring equipment are......Flat roof constructions are mainly used on commercial, institutional and industrial buildings, where insulation is placed on top of the load-bearing deck and then covered with a roof membrane. Through time, there is a risk that the membrane will allow water passage as holes might form due to...... weathering effects or physical loads. Water will then enter the insulation, and as a vapor retarder is normally found below the insulation thus trapping the water in the insulation, the leak can remain undetected for a long period. When the leak is finally discovered, the insulation has to be discharged as...

  13. Immobilization of Rocky Flats graphite fines residues

    International Nuclear Information System (INIS)

    The Savannah River Technology Center (SRTC) is developing an immobilization process for graphite fines residues generated during nuclear materials production activities at the Rocky Flats Environmental Technology Site (Rocky Flats). The continued storage of this material has been identified as an item of concern. The residue was generated during the cleaning of graphite casting molds and potentially contains reactive plutonium metal. The average residue composition is 73 wt% graphite, 15 wt% calcium fluoride (CaF2), and 12 wt% plutonium oxide (PuO2). Approximately 950 kg of this material are currently stored at Rocky Flats. The strategy of the immobilization process is to microencapsulate the residue by mixing with a sodium borosilicate (NBS) glass frit and heating at nominally 700 C. The resulting waste form would be sent to the Waste Isolation Pilot Plant (WIPP) for disposal. Since the PuO2 concentration in the residue averages 12 wt%, the immobilization process was required to meet the intent of safeguards termination criteria by limiting plutonium recoverability based on a test developed by Rocky Flats. The test required a plutonium recovery of less than 4 g/kg of waste form when a sample was leached using a nitric acid/CaF2 dissolution flowsheet. Immobilization experiments were performed using simulated graphite fines with cerium oxide (CeO2) as a surrogate for PuO2 and with actual graphite fines residues. Small-scale surrogate experiments demonstrated that a 4:1 frit to residue ratio was adequate to prevent recovery of greater than 4 g/kg of cerium from simulated waste forms. Additional experiments investigated the impact of varying concentrations of CaF2 and the temperature/heating time cycle on the cerium recovery. Optimal processing conditions developed during these experiments were subsequently demonstrated at full-scale with surrogate materials and on a smaller scale using actual graphite fines

  14. Microwave solidification development for Rocky Flats waste

    International Nuclear Information System (INIS)

    The Microwave Engineering Team at the Rocky Flats Plant has developed a production-scale system for the treatment of hazardous, radioactive, and mixed wastes using microwave energy. The system produces a vitreous final form which meets the acceptance criteria for shipment and disposal. The technology also has potential for application on various other waste streams from the public and private sectors. Technology transfer opportunities are being identified and pursued for commercialization of the microwave solidification technology

  15. Flat band superconductivity in strained Dirac materials

    OpenAIRE

    Kauppila, V. J.; Aikebaier, F.; Heikkilä, T. T.

    2016-01-01

    We consider superconducting properties of a two-dimensional Dirac material such as graphene under strain that produces a flat band spectrum in the normal state. We show that in the superconducting state, such a model results in a highly increased critical temperature compared to the case without the strain, inhomogenous order parameter with two-peak shaped local density of states and yet a large and almost uniform and isotropic supercurrent. This model could be realized in strained graphene o...

  16. Soil decontamination at Rocky Flats Plant

    International Nuclear Information System (INIS)

    A description is given of work being done at Rocky Flats Plant (RFP) to decontaminate soil contaminated with plutonium-239. How the contamination came about is described, as well as what has been done to contain it while decontamination methods are being developed. The purpose of the work is to decontaminate the soil so that it can be returned to the site instead of having to package, ship, and store it

  17. Differential flat control for rotorcraft trajectory tracking

    OpenAIRE

    Nan Zhang; Geanina Andrei; Antoine Drouin; Felix Mora-Camino

    2009-01-01

    The purpose of this communication is to investigate the usefulness of the differential flatness control approach to solve the trajectory tracking problem for a four rotor aircraft. After introducing simplifying assumptions, the flight dynamics equations for the four rotor aircraft are considered. A trajectory tracking control structure based on a two layer non linear approach is then proposed. A supervision level is introduced to take into account the actuators limitations.

  18. Stable flatness of nonarchimedean hyperenveloping algebras

    OpenAIRE

    Schmidt, Tobias

    2008-01-01

    Let L be a p-adic local field and g a finite dimensional Lie algebra over L. We show that its hyperenveloping algebra F(g) is a stably flat completion of its universal enveloping algebra. As a consequence the relative cohomology for the locally convex algebra F(g) coincides with the underlying Lie algebra cohomology. Final version. Some minor items corrected. Appeared in Journal of Algebra (2010).

  19. Wash Flats Management Plan Chincoteague National Wildlife Refuge 1980

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Wash Flats impoundments comprise an area of approximately 1,200 acres. Prior to 1963, the Wash Flats was subject to periodic wash-over during extremely high...

  20. Shrinkage and trajectory of the flat jet with inclination angle

    Institute of Scientific and Technical Information of China (English)

    Shufeng Ye; Yusheng Xie; Hongzhi Guo; Ye Huang; Shantong Jin

    2003-01-01

    The performance of the flat jet with an inclination angle was investigated by a water model. A mathematical model for theshrinkage and the trajectory of the flat jet with an inclination angle was derived theoretically and verified by experimental data of thewater model. The experimental results indicate that the inclination angle (α) has no influence on the shrinkage of the flat jet, theshrinkage of the flat jet along the width direction decreases with the increasing of the initial velocity at the exit (u0) and the initialthickness of the flat jet (t0). Enough bigger initial exit velocity (u0) and initial thickness can suppress the shrinkage of the flat jetalong the width direction and keep the flat jet stabilized. In addition, the trajectory of the flat jet with an inclination angle is parabolicand must be taking into consideration when to determine the striking distance.

  1. Design scenarios for flat panel photobioreactors

    International Nuclear Information System (INIS)

    Evaluation of the potential of algae production for biofuel and other products at various locations throughout the world requires assessment of algae productivity under varying light conditions and different reactor layouts. A model was developed to predict algae biomass production in flat panel photobioreactors using the interaction between light and algae growth for the algae species Phaeodactylum tricornutum and Thalassiosira pseudonana. The effect of location, variable sunlight and reactor layout on biomass production in single standing and parallel positioned flat panels was considered. Three latitudes were studied representing the Netherlands, France and Algeria. In single standing reactors the highest yearly biomass production is achieved in Algeria. During the year biomass production fluctuates the most in the Netherlands, while it is almost constant in Algeria. Several combinations of path lengths and biomass concentrations can result in the same optimal biomass production. The productivity in parallel place flat panels is strongly influenced by shading and diffuse light penetration between the panels. Panel orientation has a large effect on productivity and at higher latitudes the difference between north-south and east-west orientation may go up to 50%.

  2. How flat is our Universe really?

    International Nuclear Information System (INIS)

    Distance measurement provides no constraints on curvature independent of assumptions about the dark energy, raising the question, how flat is our Universe if we make no such assumptions? Allowing for general evolution of the dark energy equation of state with 20 free parameters that are allowed to cross the phantom divide, w(z)=−1, we show that while it is indeed possible to match the first peak in the Cosmic Microwave Background with non-flat models and arbitrary Hubble constant, H0, the full WMAP7 and supernova data alone imply −0.12k0 prior, this tightens significantly to Ωk=0.002±0.009. These constitute the most conservative and model-independent constraints on curvature available today, and illustrate that the curvature-dynamics degeneracy is broken by current data, with a key role played by the Integrated Sachs Wolfe effect rather than the distance to the surface of last scattering. If one imposes a quintessence prior on the dark energy (−1⩽w(z)⩽1) then just the WMAP7 and supernova data alone force the Universe to near flatness: Ωk=0.013±0.012. Finally, allowing for curvature, we find that all datasets are consistent with a Harrison–Zel'dovich spectral index, ns=1, at 2σ, illustrating the interplay between early and late Universe constraints

  3. Exotic atoms

    International Nuclear Information System (INIS)

    The experiments use a solid hydrogen layer to form muonic hydrogen isotopes that escape into vacuum. The method relies on transfer of the muon from protium to either a deuteron or a triton. The resulting muonic deuterium or muonic tritium will not immediately thermalize because of the very low elastic cross sections, and may be emitted from the surface of the layer. Measurements which detect decay electrons, muonic x-rays, and fusion products have been used to study the processes. A target has been constructed which exploits muonic atom emission in order to learn more about the energy dependence of transfer and muon molecular formation

  4. Atomic Clocks

    Science.gov (United States)

    Wynands, Robert

    Time is a strange thing. On the one hand it is arguably the most inaccessible physical phenomenon of all: both in that it is impossible to manipulate or modify—for all we know—and in that even after thousands of years mankind's philosophers still have not found a fully satisfying way to understand it. On the other hand, no other quantity can be measured with greater precision. Today's atomic clocks allow us to reproduce the length of the second as the SI unit of time with an uncertainty of a few parts in 1016—orders of magnitude better than any other quantity. In a sense, one can say [1

  5. Hubungan Kejadian Flat Foot dengan Obesitas pada Anak

    OpenAIRE

    Levenia

    2016-01-01

    Introduction. Flat foot is usually occurs and do not cause symptoms in under 5 years old children. But if occur in older children can cause pain even injury in children’s foot. One of flat foot’s risk factor is obesity. Although the prevalence of obesity is increasing every year, research of relationship between obesity and flat foot is still limited. The purpose of this research were to detect prevalence of obesity and flat foot, also to detect the relationship between obesity and flat foot ...

  6. Single atom measurement and atomic manipulation using atomic force microscope

    International Nuclear Information System (INIS)

    This paper explains studies to measure atomic force as the force linking an atom and atom, using an atomic force microscope (AFM). First, it describes the principle and device configuration of AFM, and as an example of the atomic force measurement of Si atoms on the surface of Si(111)-(7x7), it describes the technique to measure atomic force using AFM, as well as the uncertainty of probe tip against atomic force. In addition, it describes the following items on the measurement results of chemical bonding force: (1) chemical bonding force vs physical force and chemical bonding force vs current on the surface of Si(111)-(7x7), (2) chemical bonding force and element dependence on the surface of Si/Sn(111)-(√3x√3), (3) atomic manipulation based on AMF, and (4) relationship between atomic manipulation and the size of chemical bonding force with a probe. (A.O.)

  7. REVIEW OF PERFORMANCE AND ANALYSIS ISI FLAT PLATE COLLECTOR WITH MODIFIED FLAT PLATE COLLECTOR

    Directory of Open Access Journals (Sweden)

    MR.Y.Y.NANDURKAR

    2012-03-01

    Full Text Available The market of solar water heater of natural circulation type (thermo-siphon is fast growing in India. Initial cost of the solar water heater system at present is high because of store type design. It is necessary to make the product more popular by reducing the cost. This is possible by reducing area of liquid flat plate collector by increasing tube diameter and reducing riser length. Hence it is essential to make solar water heater in affordable range of the general public class. Present work is based on review of comparative performance and analysis of ISI flat plate collector with modified flat plat collector. The paper will be helpful for those who are working in the area of solar water heating system and their use in domestic areas.

  8. Buyers’ Attitude and Preference towards Flat/Apartments

    Directory of Open Access Journals (Sweden)

    R. Renganathan

    2015-04-01

    Full Text Available Nowadays people would like to have and live in their own house. Because of the growing population and lack of sufficient place, cities cannot grow horizontally. Building promoters and contractors in real estate industry are concentrating on the construction of flats/apartments even in cities like Trichy/Tamilnadu. In order to thrive and excel in the competitive environment flat promoters have to understand the expectations, tastes, preferences and lifestyle of the buyers. Two hundred and fifty customers who were living in the flats at Trichy area were included for this study. Findings of this study reveal that people living in the flats are giving importance to location of the flat, price, Swimming pool, Surveillance camera, living space, parking facility, lighting facility, lift and safety. This study will be useful for the customers to express about their opinion with regard to various aspects of flats and also useful for the flat promoters to understand about their buyers.

  9. Jet Screech Reduction with Perforated Flat Reflector

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In the present experimental study, investigations have been carried out to evaluate the performance of the new control technique of jet screech with different perforated flat reflectors. Mainly two types of porous flat reflectors had been used in the experiment. One reflector (reflector-V) designed for placing the reflector surface vertical to the jet axis, when, another type of reflector (reflector-H) designed for placing the reflecting surface horizontal to the jet axis. In both cases the reflectors had been placed at the nozzle (base tube with uniform cross-sectional area)exit. The diameter of the reflector-V was 15D when the diameter of the reflector-H was 10D. The porous area of the reflector-V was 6D and 4.5D for reflector-H where D indicated the diameter of the nozzle exit. The placement of the reflector at the exit of the nozzle reduces the sound pressure at the nozzle exit. Thus the muted sound can not excite the unstable disturbance at the nozzle exit and the loop of the feedback mechanism disappeared, finally,the generation of jet screech be cancelled. The suction space located at the back side of the porous surface of the reflector-V improves the efficiency of the screech control technique. However, in the case of reflector-H, the receptivity process of feedback loop had been controlled by reducing the disturbances at the effective shock fronts as well as at the nozzle exit. The performance of the proposed method was verified with a flat reflector concept and good performance in jet screech suppression has been confirmed in the case of porous reflector.

  10. Geotechnical risk analysis by flat dilatometer (DMT)

    Science.gov (United States)

    Amoroso, Sara; Monaco, Paola

    2015-04-01

    In the last decades we have assisted at a massive migration from laboratory testing to in situ testing, to the point that, today, in situ testing is often the major part of a geotechnical investigation. The State of the Art indicates that direct-push in situ tests, such as the Cone Penetration Test (CPT) and the Flat Dilatometer Test (DMT), are fast and convenient in situ tests for routine site investigation. In most cases the DMT estimated parameters, in particular the undrained shear strength su and the constrained modulus M, are used with the common design methods of Geotechnical Engineering for evaluating bearing capacity, settlements etc. The paper focuses on the prediction of settlements of shallow foundations, that is probably the No. 1 application of the DMT, especially in sands, where undisturbed samples cannot be retrieved, and on the risk associated with their design. A compilation of documented case histories that compare DMT-predicted vs observed settlements, was collected by Monaco et al. (2006), indicating that, in general, the constrained modulus M can be considered a reasonable "operative modulus" (relevant to foundations in "working conditions") for settlement predictions based on the traditional linear elastic approach. Indeed, the use of a site investigation method, such as DMT, that improve the accuracy of design parameters, reduces risk, and the design can then center on the site's true soil variability without parasitic test variability. In this respect, Failmezger et al. (1999, 2015) suggested to introduce Beta probability distribution, that provides a realistic and useful description of variability for geotechnical design problems. The paper estimates Beta probability distribution in research sites where DMT tests and observed settlements are available. References Failmezger, R.A., Rom, D., Ziegler, S.R. (1999). "SPT? A better approach of characterizing residual soils using other in-situ tests", Behavioral Characterics of Residual Soils, B

  11. Flat plate electrohydrodynamic heat pipe experiments

    Energy Technology Data Exchange (ETDEWEB)

    Loehrke, R.I.; Sebits, D.R.

    1975-07-01

    Performance capabilities of electrohydrodynamic (EHD) flat heat pipes were investigated using Freon 113 and Freon 11 as working fluids. All of the pipes employed straight rod electrodes to form axial liquid flow channels and tranverse grooves for capillary surface wetting. Results show: (1) the EHD pipe will prime under load; (2) voltage controlled conductance can be achieved by varying the active area of the evaporator; and (3) the average evaporator conductances measured in these experiments were consistent with those obtained in other experiments with heat pipes of similar surface geometry using the same or similar working fluids.

  12. Evolution of multidimensional flat anisotropic cosmological models

    International Nuclear Information System (INIS)

    We study the dynamics of a flat multidimensional anisotropic cosmological model filled with an anisotropic fluidlike medium. By an appropriate choice of variables, the dynamical equations reduce to a two-dimensional dynamical system. We present a detailed analysis of the time evolution of this system and the conditions of the existence of spacetime singularities. We investigate the conditions under which violent, exponential, and power-law inflation is possible. We show that dimensional reduction cannot proceed by anti-inflation (rapid contraction of internal space). Our model indicates that it is very difficult to achieve dimensional reduction by classical means

  13. Flexible Polyhedral Surfaces with Two Flat Poses

    Directory of Open Access Journals (Sweden)

    Hellmuth Stachel

    2015-05-01

    Full Text Available We present three types of polyhedral surfaces, which are continuously flexible and have not only an initial pose, where all faces are coplanar, but pass during their self-motion through another pose with coplanar faces (“flat pose”. These surfaces are examples of so-called rigid origami, since we only admit exact flexions, i.e., each face remains rigid during the motion; only the dihedral angles vary. We analyze the geometry behind Miura-ori and address Kokotsakis’ example of a flexible tessellation with the particular case of a cyclic quadrangle. Finally, we recall Bricard’s octahedra of Type 3 and their relation to strophoids.

  14. Prunus hybrids rootstocks for flat peach

    OpenAIRE

    Pilar Legua; Jorge Pinochet; María Ángeles Moreno; Juan José Martínez; Francisca Hernández

    2012-01-01

    Peach (Prunus persica L.) is the most important stone fruit tree grown in Spain and is the second most important fruit crop in Europe. The influence of eight Prunus rootstocks (GF-677, Krymsk® 86, PADAC 97-36, PADAC 99-05, PADAC 9912-03, PADAC 0024-01, PAC 0021-01 and PAC 0022-01) on vigor, yield and fruit quality traits of 'UFO 3' flat peach cultivar was studied. The highest trunk cross sectional area was exhibited by GF-677 and the lowest by PADAC 99-05, while intermediate values were found...

  15. Comment on "Conformally flat stationary axisymmetric metrics"

    CERN Document Server

    Barnes, A; Senovilla, José MM

    2003-01-01

    Garcia and Campuzano claim to have found a previously overlooked family of stationary and axisymmetric conformally flat spacetimes, contradicting an old theorem of Collinson. In both these papers it is tacitly assumed that the isometry group is orthogonally transitive. Under the same assumption, we point out here that Collinson's result still holds if one demands the existence of an axis of symmetry on which the axial Killing vector vanishes. On the other hand if the assumption of orthogonal transitivity is dropped, a wider class of metrics is allowed and it is possible to find explicit counterexamples to Collinson's result.

  16. Conformally flat anisotropic spheres in general relativity

    CERN Document Server

    Herrera, L; Ospina, J F; Fuenmayor, E

    2001-01-01

    The condition for the vanishing of the Weyl tensor is integrated in the spherically symmetric case. Then, the resulting expression is used to find new, conformally flat, interior solutions to Einstein equations for locally anisotropic fluids. The slow evolution of these models is contrasted with the evolution of models with similar energy density or radial pressure distribution but non-vanishing Weyl tensor, thereby bringing out the different role played by the Weyl tensor, the local anisotropy of pressure and the inhomogeneity of the energy density in the collapse of relativistic spheres.

  17. Euler angles as torsional flat spaces

    Science.gov (United States)

    Trejo-Mandujano, Hector A.

    In this work we use general tensor calculus to compare the geodesic equation of motion and Newton's first law for force-free classical systems that are described by an arbitrary number of generalized coordinates in spaces with and without torsion. We choose as objects of study the flat torsional Euler angle metric spaces for rigid rotators. We tested the equivalence of the two motion equations using computational software that allowed algebraic manipulation. The main result is that the equivalence only holds for torsion-free spaces, and for isotropic force-free rotators. We present analytical calculations for the isotropic case and computational results for the general case.

  18. Ultrabarrier Flexible Substrates for Flat Panel Displays

    Energy Technology Data Exchange (ETDEWEB)

    Burrows, Paul E.; Graff, Gordon L.; Gross, Mark E.; Martin, Peter M.; Shi, Ming-Kun; Hall, Michael G.; Mast, Eric S.; Bonham, Charles C.; Bennett, Wendy D.; Sullivan, Michael B.

    2001-05-01

    We describe a flexible, transparent plastic substrate for flat panel display applications. Using roll-coating techniques, we apply a composite thin film barrier to commercially available polymers, which restricts moisture and oxygen permeation to undetectable levels. The barrier film can be capped with a thin film of transparent conductive oxide in the same roll-coater, yielding an engineered substrate (Barix™) for next generation, rugged, lightweight or flexible displays. The substrate is sufficiently impermeable to moisture and oxygen for application to moisture-sensitive display applications, such as organic light emitting displays (OLEDs). This enables, for the first time, lightweight and flexible emissive organic displays.

  19. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  20. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes

    Energy Technology Data Exchange (ETDEWEB)

    Klug, Jeffrey A., E-mail: jklug@anl.gov; Emery, Jonathan D.; Martinson, Alex B. F.; Proslier, Thomas, E-mail: prolier@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Weimer, Matthew S. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Chemistry, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Yanguas-Gil, Angel; Elam, Jeffrey W. [Energy Systems Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Seifert, Sönke; Schlepütz, Christian M. [X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Hock, Adam S. [Department of Chemistry, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Chemical Science and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2015-11-15

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er{sub 2}O{sub 3} ALD on amorphous ALD alumina and single crystalline sapphire.

  1. A modular reactor design for in situ synchrotron X-ray investigation of atomic layer deposition processes

    Energy Technology Data Exchange (ETDEWEB)

    Klug, Jeffrey A.; Weimer, Matthew S.; Emery, Jonathan D.; Yanguas-Gil, Angel; Seifert, Sonke; Schleputz, Christian M.; Martinson, Alex B. F.; Elam, Jeffrey W.; Hock, Adam S.; Proslier, Thomas

    2015-11-01

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present \\textit{in situ} results for 1.) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, 2.) grazing-incidence small angle scattering of MnO nucleation on silicon, and 3.) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire.

  2. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes

    Science.gov (United States)

    Klug, Jeffrey A.; Weimer, Matthew S.; Emery, Jonathan D.; Yanguas-Gil, Angel; Seifert, Sönke; Schlepütz, Christian M.; Martinson, Alex B. F.; Elam, Jeffrey W.; Hock, Adam S.; Proslier, Thomas

    2015-11-01

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire.

  3. A modular reactor design for in situ synchrotron x-ray investigation of atomic layer deposition processes

    International Nuclear Information System (INIS)

    Synchrotron characterization techniques provide some of the most powerful tools for the study of film structure and chemistry. The brilliance and tunability of the Advanced Photon Source allow access to scattering and spectroscopic techniques unavailable with in-house laboratory setups and provide the opportunity to probe various atomic layer deposition (ALD) processes in situ starting at the very first deposition cycle. Here, we present the design and implementation of a portable ALD instrument which possesses a modular reactor scheme that enables simple experimental switchover between various beamlines and characterization techniques. As first examples, we present in situ results for (1) X-ray surface scattering and reflectivity measurements of epitaxial ZnO ALD on sapphire, (2) grazing-incidence small angle scattering of MnO nucleation on silicon, and (3) grazing-incidence X-ray absorption spectroscopy of nucleation-regime Er2O3 ALD on amorphous ALD alumina and single crystalline sapphire

  4. Cold atom microtraps above a videotape surface

    International Nuclear Information System (INIS)

    Much progress has been made in the last two years towards miniaturizing magnetic traps for cold atoms. This will enable manipulation of coherent samples of atoms, such as Bose-Einstein condensates, or single atoms, on the scale of the atomic de Broglie wavelength. This thesis concerns an array of microscopic magnetic potentials formed close to the surface of magnetized videotape, when a uniform bias field is applied. The recorded magnetization is a 100 μm sine wave, which covers a 12.5mm x 22mm piece of commercial videotape. This videotape is glued flat onto a thin glass substrate and is gold coated by evaporation so that atoms can be trapped close to the surface in a mirror-MOT. An 'atom chip' has been developed, incorporating the videotape and current-carrying wires located below the magnetized surface. A single wire and bias field create a magnetic tube potential, oriented parallel with the microtraps and with a quadrupole radial field. This allows the mirror-MOT to be compressed and distorted in order to match it to a magnetic trap formed by the same wire and bias field. Increasing the bias field and reducing the wire current further compresses the atom cloud and brings it closer to the surface, until it is fully transferred to the videotape microtraps. The atom cloud is confined axially by the potential produced by two parallel current-carrying wires with 8mm separation. This is the first demonstration of loading cold atoms into microtraps formed above a permanently magnetized surface. It is interesting to compare the properties of such traps with those formed above current carrying wires. We present measurements of the lifetimes of trapped atom clouds as a function of height and trap frequency. These results suggest that this technology may prove to be a promising basis for future experiments with atom chips. (author)

  5. Risk, media, and stigma at Rocky Flats

    International Nuclear Information System (INIS)

    Public responses to nuclear technologies are often strongly negative. Events, such as accidents or evidence of unsafe conditions at nuclear facilities, receive extensive and dramatic coverage by the news media. These news stories affect public perceptions of nuclear risks and the geographic areas near nuclear facilities. One result of these perceptions, avoidance behavior, is a form of technological stigma that leads to losses in property values near nuclear facilities. The social amplification of risk is a conceptual framework that attempts to explain how stigma is created through media transmission of information about hazardous places and public perceptions and decisions. This paper examines stigma associated with the US Department of energy's Rocky Flats facility, a major production plant in the nation's nuclear weapons complex, located near Denver, Colorado. This study, based upon newspaper analyses and a survey of Denver area residents, finds that the social amplification theory provides a reasonable framework for understanding the events and public responses that took place in regard to Rocky Flats during a 6-year period, beginning with an FBI raid of the facility in 1989

  6. Development of flat panel digital radiography system

    International Nuclear Information System (INIS)

    We developed the Digital Radiography System CXDI-11 which digitizes the X-ray image in high quality by using a self-developed flat panel detector. The CXDI-11 has a large image area of 43 cm x 43 cm (17'' x 17''), and it can display the image on the pre-view monitor after only 3 seconds of exposure. In this report, we present the principle and the physical characteristics of the CXDI-11. The X-ray detector installed in the CXDI-11 is a combination of a rare-earth scintillator and an amorphous silicon flat panel detector (LANMIT). The X-ray is converted to the visible fluorescent light at the scintillator and the light is detected by the LANMIT. The image-processed data is transferred to the DICOM3.0 conformed devices such as the diagnosis work station, the archiver and the laser imager through the network. We also show some measurement results of the dynamic range, the pre-sampling Modulation Transfer Function and the tube voltage dependent sensitivity. The CXDI-11 is superior in real time operation and image quality, thus it is the digital radiography system of the next generation. (author)

  7. Maxey Flats in situ waste grouting demonstration

    International Nuclear Information System (INIS)

    The Maxey Flats Disposal Site located in Fleming County, Kentucky was added to the US EPA National Priority List in 1986 and is currently being evaluated for remediation and closure under the CERCLA/Superfund program. The Commonwealth of Kentucky has cosponsored a program with the US DOE Low Level Waste Management Program to demonstrate various remedial technologies which may be applied to source containment at the Maxey Flats site. This paper describes the field demonstration of in-situ waste grouting using a particulate (cement) grout. This demonstration is a follow-on to a similar demonstration using a solution grout. Both programs were designed to develop injection techniques, to assess the ability of the grout to fill the accessible voids within the waste/backfill matrix, to measure the reduction in the hydraulic conductivity of the waste/backfill matrix, and to determine the operational difficulties in implementing a site-wide grouting program. The paper concludes with lessons-learned during the project and estimated costs for full scale implementation

  8. Cosmological consequences of supersymmetric flat directions

    CERN Document Server

    Riva, Francesco; Sarkar, Subir; Giudice, Gian

    In this work we analyze various implications of the presence of large field vacum expectation values (VEVs) along supersymmetric flat direct ions during the early universe. First, we discuss supersymmetric leptogenesis and the grav itino bound. Supersym- metric thermal leptogenesis with a hierarchical right-han ded neutrino mass spectrum normally requires the mass of the lightest right-handed neu trino to be heavier than about 10 9 GeV. This is in conflict with the upper bound on the reheating t empera- ture which is found by imposing that the gravitinos generate d during the reheating stage after inflation do not jeopardize successful nucleosy nthesis. We show that a solution to this tension is actually already incorporated i n the framework, because of the presence of flat directions in the supersymmetric scalar potential. Massive right- handed neutrinos are efficiently produced non-thermally and the observed baryon asymmetry can be explained even for a reheating temperature respecting the grav- itino bound...

  9. Pond fractals in a tidal flat.

    Science.gov (United States)

    Cael, B B; Lambert, Bennett; Bisson, Kelsey

    2015-11-01

    Studies over the past decade have reported power-law distributions for the areas of terrestrial lakes and Arctic melt ponds, as well as fractal relationships between their areas and coastlines. Here we report similar fractal structure of ponds in a tidal flat, thereby extending the spatial and temporal scales on which such phenomena have been observed in geophysical systems. Images taken during low tide of a tidal flat in Damariscotta, Maine, reveal a well-resolved power-law distribution of pond sizes over three orders of magnitude with a consistent fractal area-perimeter relationship. The data are consistent with the predictions of percolation theory for unscreened perimeters and scale-free cluster size distributions and are robust to alterations of the image processing procedure. The small spatial and temporal scales of these data suggest this easily observable system may serve as a useful model for investigating the evolution of pond geometries, while emphasizing the generality of fractal behavior in geophysical surfaces. PMID:26651668

  10. Pure and Zn-doped Pt Clusters go Flat and Upright on MgO(100)

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Lu; Dadras, Mostafa J.; Alexandrova, Anastassia N.

    2014-12-28

    Pure and doped sub-nanoclusters can exhibit superb catalytic activity, which, however, strongly depends on their size, shape, composition, and the nature of the support. This work is about surface-deposited sub-nano Pt-based clusters, which are promising catalysts for the reactions of dehydrogenation. Using density functional theory and ab initio calculations, and an ab initio genetic algorithm for finding the global minima of clusters, we found a peculiar effect that Pt₅ and Pt₄Zn clusters exhibit upon deposition on MgO(100). Both of them change shapes from the gas phase 3-D form to a planar form, and they stand upright on the support. Several reasons are responsible for this behaviour. In part, clusters go flat due to the electron transfer from the support. Indeed, the anionic Pt₅- and Pt₄Zn- species are flat also in the gas phase. Charging induces the second-order Jahn–Teller effect (or partial covalency) facilitated by the recruitment of the higher-energy 6p atomic orbitals on Pt into the valence manifold, and that is the reason for the planarization of the anions. Secondly, clusters maximize interactions with the surface O atoms (resulting in further favouring of 2-D structures over 3-D), and avoid contacts with surface Mg atoms (resulting in upright morphologies).

  11. Trophic relationships in tidal flat areas: To what extent are tidal flats dependent on imported food?

    Science.gov (United States)

    Asmus, Harald; Asmus, Ragnhild M.

    In four intertidal areas of 'Königshafen' (island of Sylt, FRG), biomass and production of macrozoobenthos were measured monthly in 1980 and 1984. The areas were characterized by different macrofauna assemblages ( Nereis-Corophium belt, seagrass bed, Arenicola flat and mussel bed). Biomass and production of macrofauna were partitioned with regard to food preference of single species as well as to the food availability within their habitat. In the Nereis-Corophium belt, seagrass bed and the Arenicola flat, most of the secondary production of the macrofauna was formed by grazing animals. Secondary production of mussel beds was nearly 10 times higher than in the other three assemblages. The suspension feeder assemblage depended on planktonic food imported from outside the bay. Considering the secondary production of the total tidal flat area, suspension feeders dominated the other trophic groups, indicating a key position of this group relative to the other macrofaunal assemblages. Mussel beds regulate the seston input to other communities situated further landward. Because of this dominance of the suspension feeder group, the energy and material flow of the total tidal flat is strongly dependent on the seston input from the coastal waters of the North Sea or from other parts of the Wadden Sea.

  12. Single phase ZnO submicrotubes as a replica of electrospun polymer fiber template by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gyeong-Man, E-mail: gmkim@ceit.es [CEIT and TECNUN, University of Navarra, Paseo de Mikeletegi 48, 20009 Donostia-San Sebastian (Spain); Lee, Seung-Mo [Nano-Mechanical Systems Research Division, Korea Institute of Machinery and Materials (KIMM), 156 Gajungbukno, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Knez, Mato [Nanomaterials Group, CIC nanoGUNE, Tolosa Hiribidea 76, E-20018 Donostia-San Sebastian (Spain); Simon, Paul [Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, D-01187 Dresden (Germany)

    2014-07-01

    Free-standing and highly interconnected ZnO tubes consisting of nanostructured single phase grains are fabricated by atomic layer deposition (ALD) combined with the electrospinning technique. Hereby, electrospun poly(vinyl pyrrolidone) fiber mat is used as a soft template for coating with zinc oxide. The deposition is conducted onto the template at 70 °C by using diethylzinc and water as ALD precursors. The crystal structure, microstructure and optical properties of the ZnO deposited layers are studied in detail by transmission electron microscopy and X-ray diffraction before and after calcination. After calcination in air at 500 °C for 4 h the morphology of the wedge-like grains transforms into platelet-like structures with lattice parameters similar to those of the standard bulk polycrystalline ZnO. The resulting nanostructured ZnO tubes exhibit unique optical properties, which arose from the quantum-confinement of ZnO thin films prepared by ALD. The measured band gap energies for both the as-deposited and the calcined ZnO films are much lower than that of bulk ZnO or the single crystalline ZnO. Furthermore, the ultraviolet light is completely absorbed in both cases. The self-supported free-standing polycrystalline ZnO tubes can be easily handled and are bearing high potential for future applications related to catalysis, electronics, photonics, sensing, medicine and controlled drug release. - Highlights: • ZnO tubes were replicated from the electrospun fibers by atomic layer deposition. • ZnO tubes exhibited unique optical properties from their quantum-confinement. • Band gap energies for ZnO films are much lower than for single crystalline ZnO. • Ultraviolet light is completely absorbed by ZnO tubes. • Such self-supported ZnO tubes can be reclaimed for use in future applications.

  13. Effects of atomic geometry and electronic structure of platinum surfaces on molecular adsorbates studied by gap-mode SERS.

    Science.gov (United States)

    Hu, Jian; Tanabe, Masahiro; Sato, Jun; Uosaki, Kohei; Ikeda, Katsuyoshi

    2014-07-23

    Surface enhanced Raman scattering (SERS) spectra of organic monolayers were measured on various types of polycrystalline and single crystalline Pt substrates with nanometric or atomic surface features, including heteroepitaxial Pt monolayers, using sphere-plane type nanogap structures. Although atomic geometry and electronic structures of a metal surface significantly influence metal-molecule interactions, such effects are often hindered in conventional SERS measured on a roughened surface because of the spectral information averaging at various adsorption sites. In this study, the use of atomically defined Pt surfaces revealed detailed surface effects; the observed preferential adsorption geometry on each surface was well explained by atomic surface arrangements. The peak shift of the intramolecular vibration in the anchor group was in good agreement with the variation of the d-band center of Pt substrates. Moreover, in electrochemical SERS study the Stark shift of an extramolecular vibrational mode at around 400 cm(-1), which is not accessible in infrared absorption spectroscopy, was monitored on an atomically defined heteroepitaxial Pt monolayer electrode. PMID:24802029

  14. Examination of the anisotropy of the wetting behaviour of liquid Al-Cu alloys on single crystalline oriented Al{sub 2}O{sub 3}-substrates; Untersuchung der Anisotropie im Benetzungsverhalten fluessiger Al-Cu Legierungen auf einkristallinen orientierten Al{sub 2}O{sub 3}-Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Julianna

    2011-02-04

    The wetting behaviour of liquid Al-Cu alloys and pure metals on oriented single crystalline Al{sub 2}O{sub 3}-substrates was examined, utilising the sessile drop technique. Measurements were performed at moderate temperatures of 1100 C, where the alloys are liquid. Different Al{sub 2}O{sub 3}-surfaces were studied, which are terminated by the crystallographic planes (0001), (11 anti 20), and (1 anti 102), also called C-, A-, and R-surfaces. After deposition, pure Cu-droplets show an exponential increase of the wetting angle to a value of about 115 for all investigated Al{sub 2}O{sub 3}-surfaces. The timescale of this increase is of the order of 100 s. The effect of surface- and interfacial energies on the wetting angle is discussed considering Young's equation. The most probable reason for its time-dependence seems to be an increase of the interfacial energy due to deoxidation of the droplet. Therefore it is reasonable to regard the isotropic contact angle value as the intrinsic one of the Cu/Al{sub 2}O{sub 3} system. In contrast, the wetting angle of pure Al metal with the different Al{sub 2}O{sub 3}-substrates shows a qualitatively different behaviour. In this system, it rises from about 90 to 115 roughly for C-substrates, twice as fast as in the Cu case but to a comparable value. On the other substrates a wetting angle of about 90 establishes immediately, and no pronounced time dependence is obvious. In order to study changes in the wetting behaviour of Al-Cu-alloys, which is isotropic for Cu and anisotropic for Al-rich alloys, contact angles of Al{sub 50}Cu{sub 50}, Al{sub 30}Cu{sub 70} und Al{sub 17}Cu{sub 83} on Al{sub 2}O{sub 3} were determined. For each alloy composition the wetting angle is about 120 after 300 s. The initial values on distinct surfaces hardly differ and become non-wetting with increasing Cu-content. Hence, anisotropy decreases. To determine the work of adhesion of the solid-liquid interface, the temperature- and composition

  15. Holography of 3D Asymptotically Flat Black Holes

    CERN Document Server

    Fareghbal, Reza

    2014-01-01

    We study the asymptotically flat rotating hairy black hole solution of a three-dimensional gravity theory which is given by taking flat-space limit (zero cosmological constant limit) of New Massive Gravity (NMG). We propose that the dual field theory of the flat-space limit of NMG can be described by a Contracted Conformal Field Theory (CCFT). Using Flat/CCFT correspondence we construct a stress tensor which yields the conserved charges of the asymptotically flat black hole solution. Furthermore, by taking appropriate limit of the Cardy formula in the parent CFT, we find a Cardy-like formula which reproduces the Wald's entropy of the 3D asymptotically flat black hole.

  16. Spin–orbit-coupled BEC in a double-well potential: Quantum energy spectrum and flat band

    International Nuclear Information System (INIS)

    Spin–orbit-coupled Bose–Einstein condensates (BECs) provide a powerful platform for studies on physical problems in various fields. Here we study the energy spectrum of a tunable spin–orbit-coupled BEC in a double-well potential with adjustable Raman laser intensity. We find in the single-particle spectrum there is a highly degenerate flat band in the ground state of the BEC, which remains stable against changes of the Raman strength. Many-body interactions between atoms remove this high degeneracy. Analytical results for particular cases are obtained by using the perturbation theory, which are in good agreement with the numerical results. - Highlights: • Energy spectrum of a tunable SOC BEC in a double-well potential is obtained. • Single-particle spectrum shows a highly degenerate flat band in the ground state. • Weak interactions between atoms remove this high degeneracy. • Analytical results are obtained by perturbation theory

  17. Knitting Force Measurement on Flat Knitting Machines

    Directory of Open Access Journals (Sweden)

    A. Fouda

    2014-01-01

    Full Text Available Knittability can be defined as the ability of yarns to run on knitting machines without problems. Knittability can be achieved when less stress is applied on the knitting machine parts by the knitting yarns. This paper presents a novel measuring system for the knitting force needed to perform knitting yarns on flat knitting machine based on data acquisition system (DAS. The proposed system is used to measure the knitting force at different machine settings and different properties of the knitting yarns to determine the optimal production conditions. For this reason, three types of knitted fabric structures (single jersey, Rib 1 × 1, and full cardigan with three different loop lengths and five different twists of ply yarn were produced. The obtained results showed the optimal yarn ply twist factor (αe which gave minimum knitting force (less stress on needles or knitting yarns at different loop lengths for each structure.

  18. Traversable asymptotically flat wormholes in Rastall gravity

    CERN Document Server

    Moradpour, H

    2016-01-01

    Having introduced the Rastall gravitational theory, and by virtue of the fact that this theory has two unknown parameters, we take the Newtonian limit to define a new parameter for Rastall gravitational theory; a useful dimensionless parameter for simplifying calculations in the Rastall framework. Equipped with basics of the theory, we study the properties of traversable asymptotically flat wormholes in Rastall framework. Then, we investigate the possibility of supporting such geometries by a source with the same state parameter as that of the baryonic matters. Our survey indicates that the parameters of Rastall theory affect the wormhole parameters. It also shows the weak energy condition is violated for all of the studied cases. We then come to investigate the possibility of supporting such geometries by a source of negative energy density and the same state parameter as that of dark energy. Such dark energy-like sources have positive radial and transverse pressures.

  19. A quantum kinematics for asymptotically flat spacetimes

    CERN Document Server

    Campiglia, Miguel

    2014-01-01

    We construct a quantum kinematics for asymptotically flat spacetimes based on the Koslowski-Sahlmann (KS) representation. The KS representation is a generalization of the representation underlying Loop Quantum Gravity (LQG) which supports, in addition to the usual LQG operators, the action of `background exponential operators' which are connection dependent operators labelled by `background' $su(2)$ electric fields. KS states have, in addition to the LQG state label corresponding to 1 dimensional excitations of the triad, a label corresponding to a `background' electric field which describes 3 dimensional excitations of the triad. Asymptotic behaviour in quantum theory is controlled through asymptotic conditions on the background electric fields which label the {\\em states} and the background electric fields which label the {\\em operators}. Asymptotic conditions on the triad are imposed as conditions on the background electric field state label while confining the LQG spin net graph labels to compact sets. We...

  20. Flat tensile specimen design for advanced composites

    Science.gov (United States)

    Worthem, Dennis W.

    1990-01-01

    Finite element analyses of flat, reduced gage section tensile specimens with various transition region contours were performed. Within dimensional constraints, such as maximum length, tab region width, gage width, gage length, and minimum tab length, a transition contour radius of 41.9 cm produced the lowest stress values in the specimen transition region. The stresses in the transition region were not sensitive to specimen material properties. The stresses in the tab region were sensitive to specimen composite and/or tab material properties. An evaluation of stresses with different specimen composite and tab material combinations must account for material nonlinearity of both the tab and the specimen composite. Material nonlinearity can either relieve stresses in the composite under the tab or elevate them to cause failure under the tab.

  1. Pulsar Magnetospheres: Beyond the Flat Spacetime Dipole

    CERN Document Server

    Gralla, Samuel E; Philippov, Alexander

    2016-01-01

    Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields may have a significant nondipolar component. We introduce a general analytical method for studying the axisymmetric force-free magnetosphere of a slowly-rotating star of arbitrary magnetic field, mass, radius and moment of inertia, including all the effects of general relativity. We confirm that spacelike current is generically present in the polar caps (suggesting a pair production region), irrespective of the stellar magnetic field. We show that general relativity introduces a ~60% correction to the formula for the dipolar component of the surface magnetic field inferred from spindown. Finally, we show that the location and size of the polar caps can be modified dramatically by even modestly strong higher moments. This can affect emission processes occurring near the star ...

  2. Rigidity of noncompact complete Bach-flat manifolds

    Science.gov (United States)

    Kim, Seongtag

    2010-04-01

    Let (M,g) be a noncompact complete Bach-flat manifold with positive Yamabe constant. We prove that (M,g) is flat if (M,g) has zero scalar curvature and sufficiently small L2 bound of curvature tensor. When (M,g) has nonconstant scalar curvature, we prove that (M,g) is conformal to the flat space if (M,g) has sufficiently small L2 bound of curvature tensor and L bound of scalar curvature.

  3. Geometric origin of superfluidity in the Lieb lattice flat band

    OpenAIRE

    Julku, Aleksi; Peotta, Sebastiano; Vanhala, Tuomas; Kim, Dong-Hee; Törmä, Päivi

    2016-01-01

    The ground state and transport properties of the Lieb lattice flat band in the presence of an attractive Hubbard interaction are considered. It is shown that the superfluid weight can be large even for an isolated and strictly flat band. Moreover the superfluid weight is proportional to the interaction strength and to the quantum metric, a band structure invariant obtained from the flat-band Bloch functions. These predictions are amenable to verification with ultracold gases and may explain t...

  4. Flat connection, conformal field theory and quantum group

    International Nuclear Information System (INIS)

    General framework of linear first order differential equation for four-point conformal block is studied by using flat connection. Integrability and SL2 invariance restrict possible form of flat connection. Under a special ansatz classical Yang-Baxter equation appears as an integrability condition and the WZW model turns to be unique conformal field theory in that case. Monodromy property of conformal block can be easily determined by the flat connection. 11 refs

  5. Hyperbolic groups have flat-rank at most 1

    CERN Document Server

    Baumgartner, Udo; Willis, George A

    2009-01-01

    The flat-rank of a totally disconnected, locally compact group G is an integer, which is an invariant of G as a topological group. We generalize the concept of hyperbolic groups to the topological context and show that a totally disconnected, locally compact, hyperbolic group has flat-rank at most 1. It follows that the simple totally disconnected locally compact groups constructed by Paulin and Haglund have flat-rank at most 1.

  6. Transverse modes for flat inter-bunch wakes

    CERN Document Server

    Burov, Alexey

    2013-01-01

    If inter-bunch wake fields are flat, i.e. their variations over a bunch length can be neglected, all coherent modes have the same coupled-bunch structure, provided the bunches can be treated as identical by their inner qualities (train theorem). If a flat feedback is strong enough, the transverse modes are single-bunch, provided the inter-bunch wakes are also flat (damper theorem).

  7. TRANSVERSE MODES FOR FLAT INTER-BUNCH WAKES*

    CERN Document Server

    Burov, A

    2013-01-01

    If inter-bunch wake fields are flat, i.e. their variations over a bunch length can be neglected, all coherent modes have the same coupled-bunch structure, provided the bunches can be treated as identical by their inner qualities (train theorem). If a flat feedback is strong enough, the transverse modes are single-bunch, provided the inter-bunch wakes are also flat (damper theorem).

  8. Treatment field specific IMRT QA using flat panel

    International Nuclear Information System (INIS)

    Electronic portal imaging devices are commonly used for geometric verification of patient positioning during the treatment. However their use has been increasingly extended in extracting dosimetric information of the radiation treatment. To extend the use of flat panel for dosimetric purposes few characteristics of the flat panel like reproducibility, temporal stability, ghosting effect, dose-response relationship have to be studied. This work presents the use of flat panel for the relative verification of individual treatment field fluence for IMRT

  9. Creation Of Constructed Tidal Flats Using Ocean Dredged Sediment

    Science.gov (United States)

    Park, S.; Yi, B.; Lee, I.; Sung, K.

    2007-12-01

    The enforcement of London dumping convention (1972) and protocols (1996) which are comprehensive assessment system for ocean dumping wastes needs environmentally sound treatment and/or reuse of dredged sediment. Creation of constructed tidal flats using dredged sediments could be one of the useful alternatives among other dredged sediment treatments. In this study, the pilot-scale constructed tidal flats with 4 different mixing ratio of ocean dredged sediment were constructed in Nakdong river estuary, Korea. The reed was transplanted from the adjacent reed community after construction, and then the survival and growth rate of the planted reed was measured. Also the changes of Chemical Oxygen Demand (COD), Ignition loss (IL), and the heterotrophic microbial numbers were monitored. The survival rate of the planted reed decreased as the mixing ratio of dredged sediment increased. The survival rate of reed in the constructed tidal flat with 100% dredged sediment was 54% while that in the tidal flat with 0% dredged sediment (original soil of Nakdong river estuary) was 90%. There was little difference of length and diameter of the reed shoot among the 4 different constructed tidal flats. 30% of COD and 9% of IL in the tidal flat with 100% dredged sediment decreased after 202 day, however, the consistent tendency in the change of COD and IL in the other tidal flats was not found possibly due to the open system. It was suggested that the construction of tidal flats using ocean dredged sediment can be possible considering the growth rate of transplanted reeds and the contaminated ocean dredged sediment might be biologically remediated considering the results of decrease of organic matter and increased heterotrophic microbial number in the tidal flat with 100% dredged sediment. However, the continuous monitoring on the vegetation and various environmental factors in the constructed tidal flats should be necessary to evaluate the success of creation of constructed flats using

  10. Rocky Flats Closure Unit Cost Data

    International Nuclear Information System (INIS)

    The Rocky Flats Closure Project has completed the process of stabilizing residual nuclear materials, decommissioning nuclear facilities, remediating environmental media and closing the Rocky Flats Site (Site). The project cost approximately $4.1 B and included the decommissioning of over 700 structures including 5 major plutonium facilities and 5 major uranium facilities, shipping over 14,600 cubic meters of transuranic and 565,000 cubic meters of low level radioactive waste, and remediating a 385-acre industrial area and the surrounding land. Actual costs were collected for a large variety of closure activities. These costs can be correlated with metrics associated with the facilities and environmental media to capture cost factors from the project that could be applicable to a variety of other closure projects both within and outside of the Department of Energy's weapons complex. The paper covers four general topics: the process to correlate the actual costs and metrics, an example of the correlated data for one large sub-project, a discussion of the results, and the additional activities that are planned to correlate and make this data available to the public. The process to collect and arrange the project control data of the Closure Project relied on the actual Closure Project cost information. It was used to correlate these actual costs with the metrics for the physical work, such as building area or waste generated, to support the development of parametric cost factors. The example provides cost factors for the Industrial Sites Project. The discussion addresses the strengths and weaknesses of the data, followed by a section identifying future activities to improve and extend the analyses and integrate it within the Department's Environmental Cost Analysis System. (authors)

  11. Constitution method of flat-band. Harmony played by molecules

    International Nuclear Information System (INIS)

    This paper introduces the constitution method of a tight-binding model where flat-band appears. Firstly, it describes the display of tight-binding model using the second quantization, as well as the constitution of the eigenstate, graph, and hopping matrix. Then, it takes up the flat-band that robustly appears regardless of the details of elements of the hopping matrix, and introduces the constitution method of flat-band for each of bipartite graph and non-bipartite graph. This type of flat-band in the case of bipartite depends on difference in the number of the sites of A sublattice and B sublattice. On the other hand, the flat-band that depends on the details of elements of the hopping matrix appears when the energy levels of molecules embedded on the lattice resonate. The following are described on this type of flat-band: (1) system where rings with magnetic flux that are seemingly not related to flat-band combine, (2) flat-band of decorated square lattice, and (3) relationship between flat-band and localization state. (A.O.)

  12. Integrin-Specific Mechanoresponses to Compression and Extension Probed by Cylindrical Flat-Ended AFM Tips in Lung Cells

    OpenAIRE

    Irene Acerbi; Tomás Luque; Alícia Giménez; Marta Puig; Noemi Reguart; Ramon Farré; Daniel Navajas; Jordi Alcaraz

    2012-01-01

    Cells from lung and other tissues are subjected to forces of opposing directions that are largely transmitted through integrin-mediated adhesions. How cells respond to force bidirectionality remains ill defined. To address this question, we nanofabricated flat-ended cylindrical Atomic Force Microscopy (AFM) tips with ~1 µm(2) cross-section area. Tips were uncoated or coated with either integrin-specific (RGD) or non-specific (RGE/BSA) molecules, brought into contact with lung epithelial cells...

  13. Doping Scheme in Atomic Chain Electronics

    Science.gov (United States)

    Toshishige, Yamada

    1997-01-01

    Due to the dramatic reduction in MOS size, there appear many unwanted effects. In these small devices, the number of dopant atoms in the channel is not macroscopic and electrons may suffer significantly different scattering from device to device since the spatial distribution of dopant atoms is no longer regarded as continuous. This prohibits integration, while it is impossible to control such dopant positions within atomic scale. A fundamental solution is to create electronics with simple but atomically precise structures, which could be fabricated with recent atom manipulation technology. All the constituent atoms are placed as planned, and then the device characteristics are deviation-free, which is mandatory for integration. Atomic chain electronics belongs to this category. Foreign atom chains or arrays form devices, and they are placed on the atomically flat substrate surface. We can design the band structure and the resultant Fermi energy of these structures by manipulating the lattice constant. Using the tight-binding theory with universal parameters, it has been predicted that isolated Si chains and arrays are metallic, Mg chains are insulating, and Mg arrays have metallic and insulating phases [1]. The transport properties along a metallic chain have been studied, emphasizing the role of the contact to electrodes [2]. For electronic applications, it is essential to establish a method to dope a semiconducting chain, which is to control the Fermi energy position without altering the original band structure. If we replace some of the chain atoms with dopant atoms randomly, the electrons will see random potential along die chain and will be localized strongly in space (Anderson localization). However, if we replace periodically, although the electrons can spread over the chain, there will generally appear new bands and band gaps reflecting the new periodicity of dopant atoms. This will change the original band structure significantly. In order to overcome

  14. Optimization of Neutral Atom Imagers

    Science.gov (United States)

    Shappirio, M.; Coplan, M.; Balsamo, E.; Chornay, D.; Collier, M.; Hughes, P.; Keller, J.; Ogilvie, K.; Williams, E.

    2008-01-01

    The interactions between plasma structures and neutral atom populations in interplanetary space can be effectively studied with energetic neutral atom imagers. For neutral atoms with energies less than 1 keV, the most efficient detection method that preserves direction and energy information is conversion to negative ions on surfaces. We have examined a variety of surface materials and conversion geometries in order to identify the factors that determine conversion efficiency. For chemically and physically stable surfaces smoothness is of primary importance while properties such as work function have no obvious correlation to conversion efficiency. For the noble metals, tungsten, silicon, and graphite with comparable smoothness, conversion efficiency varies by a factor of two to three. We have also examined the way in which surface conversion efficiency varies with the angle of incidence of the neutral atom and have found that the highest efficiencies are obtained at angles of incidence greater then 80deg. The conversion efficiency of silicon, tungsten and graphite were examined most closely and the energy dependent variation of conversion efficiency measured over a range of incident angles. We have also developed methods for micromachining silicon in order to reduce the volume to surface area over that of a single flat surface and have been able to reduce volume to surface area ratios by up to a factor of 60. With smooth micro-machined surfaces of the optimum geometry, conversion efficiencies can be increased by an order of magnitude over instruments like LENA on the IMAGE spacecraft without increase the instruments mass or volume.

  15. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  16. Portable low-cost flat panel detectors for real-time digital radiography

    International Nuclear Information System (INIS)

    The X-ray inspection is one of the most common used non-destructive testing methods in industry applications, but for the portable X-ray digital solution are not so many accessible, low-cost and versatile detection devices. The efficiency of a non-destructive X-ray portable device is represented by the quality of digital images, by its low acquisition time combined with a high resolution, in condition of low noise and at an affordable cost. The paper presents two X-ray portable imaging systems developed by us, suitable also for aerospace NDT applications, which are also very versatile for being easily adapted for other fields that requires mobile solutions. The first device described in the paper represent a portable large-size (210 mm X 550 mm) and high-resolution (27/54 microns) flat panel detector based on linear translation of a X-Ray TDI detector, destined for various components/parts real-time transmission measurements. The second system it is also a flat panel detectors, with a size of 510 mm X 610 mm, with the detector size from 0.2 mm until 1.5 mm, which can operate by applying the dual-energy method, very useful for discriminating materials by evaluating their Atomic effective number. The high resolution and low-cost of this flat-panels widens their applicability by covering large requirements, from identifying unwanted materials within a structure until detection of very thin cracks in complex components.

  17. Portable low-cost flat panel detectors for real-time digital radiography

    Energy Technology Data Exchange (ETDEWEB)

    Iovea, Mihai; Neagu, Marian; Stefanescu, Bogdan; Mateiasi, Gabriela; Porosnicu, Ioana; Angheluta, Elena [Accent Pro 2000 S.R.L., Bucharest (Romania)

    2015-07-01

    The X-ray inspection is one of the most common used non-destructive testing methods in industry applications, but for the portable X-ray digital solution are not so many accessible, low-cost and versatile detection devices. The efficiency of a non-destructive X-ray portable device is represented by the quality of digital images, by its low acquisition time combined with a high resolution, in condition of low noise and at an affordable cost. The paper presents two X-ray portable imaging systems developed by us, suitable also for aerospace NDT applications, which are also very versatile for being easily adapted for other fields that requires mobile solutions. The first device described in the paper represent a portable large-size (210 mm X 550 mm) and high-resolution (27/54 microns) flat panel detector based on linear translation of a X-Ray TDI detector, destined for various components/parts real-time transmission measurements. The second system it is also a flat panel detectors, with a size of 510 mm X 610 mm, with the detector size from 0.2 mm until 1.5 mm, which can operate by applying the dual-energy method, very useful for discriminating materials by evaluating their Atomic effective number. The high resolution and low-cost of this flat-panels widens their applicability by covering large requirements, from identifying unwanted materials within a structure until detection of very thin cracks in complex components.

  18. Cold atom microtraps above a videotape surface

    CERN Document Server

    Retter, J A

    2002-01-01

    Much progress has been made in the last two years towards miniaturizing magnetic traps for cold atoms. This will enable manipulation of coherent samples of atoms, such as Bose-Einstein condensates, or single atoms, on the scale of the atomic de Broglie wavelength. This thesis concerns an array of microscopic magnetic potentials formed close to the surface of magnetized videotape, when a uniform bias field is applied. The recorded magnetization is a 100 mu m sine wave, which covers a 12.5mm x 22mm piece of commercial videotape. This videotape is glued flat onto a thin glass substrate and is gold coated by evaporation so that atoms can be trapped close to the surface in a mirror-MOT. An 'atom chip' has been developed, incorporating the videotape and current-carrying wires located below the magnetized surface. A single wire and bias field create a magnetic tube potential, oriented parallel with the microtraps and with a quadrupole radial field. This allows the mirror-MOT to be compressed and distorted in order t...

  19. Atomic Energy Basics, Understanding the Atom Series.

    Science.gov (United States)

    Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

    This booklet is part of the "Understanding the Atom Series," though it is a later edition and not included in the original set of 51 booklets. A basic survey of the principles of nuclear energy and most important applications are provided. These major topics are examined: matter has molecules and atoms, the atom has electrons, the nucleus,…

  20. Sensor emplacement testing at Poker Flat, Alaska

    Science.gov (United States)

    Reusch, A.; Beaudoin, B. C.; Anderson, K. E.; Azevedo, S.; Carothers, L.; Love, M.; Miller, P. E.; Parker, T.; Pfeifer, M.; Slad, G.; Thomas, D.; Aderhold, K.

    2013-12-01

    PASSCAL provides equipment and support for temporary seismic projects. Speed and efficiency of deployments are essential. A revised emplacement technique of putting broadband sensors directly into soil (aka direct burial) is being tested. The first phase (fall 2011 to spring 2013) comparing data quality and sensor stability between the direct burial and the traditional 1 m deep temporary PASSCAL-style vault in a wet and noisy site near San Antonio, NM is complete. Results suggest there is little or no difference in sensor performance in the relatively high-noise environment of this initial test. The second phase was started in November 2012 with the goal of making the same comparison, but at Poker Flat, Alaska, in a low-noise, high-signal, cold and wet environment, alongside a Transportable Array (TA) deployment to be used as a performance control. This location is in an accessible and secure area with very low site noise. In addition to benefiting future worldwide PASSCAL deployments, the Poker Flat experiment serves a secondary purpose of testing modifications necessary to successfully deploy and recover broadband stations in a cold environment with the limited logistics anticipated for remote Flexible Array (FA) and PASSCAL Program deployments in Alaska. Developing emplacement techniques that maintain high data quality and data return while minimizing logistics is critical to enable principle investigators to effectively and efficiently co-locate within the future TA Alaska footprint. Three Nanometrics sensors were installed in November 2012 in power-augered holes 76 cm in depth: a Trillium Compact Posthole (PH) and two Trillium 120PH units (one standard PH and one enhanced PHQ). The installations took less than 8 hours in -30°C conditions with 4 hours of usable daylight. The Compact PH and the 120PHQ are delivering data in realtime, while the 120PH is testing standalone power and data collection systems. Preliminary results compare favorably to each other as

  1. The Psycholinguistics of Literacy in a Flat World

    Science.gov (United States)

    Horning, Alice S.

    2009-01-01

    If Friedman is right that the world is "flat," we need to understand the linguistic implications of that claim. In this increasingly flat world, classical critical literacy is both urgently needed and poorly understood from a linguistic perspective. Three claims based on research on reading can improve both the understanding of the common…

  2. The Discourses of OERs: How "Flat" Is This World?

    Science.gov (United States)

    dos Santos, Andreia Inamorato

    2008-01-01

    This paper proposes Critical Discourse Analysis (Fairclough, 2000) as a tool for identifying the various discourses that can be found in the provision of open educational resources. The argument will be built upon the concept of a "flat world", a powerful metaphor used by Friedman in his famous book "The World is Flat" (2005). The discussion will…

  3. The World Is Not Flat: Can People Reorient Using Slope?

    Science.gov (United States)

    Nardi, Daniele; Newcombe, Nora S.; Shipley, Thomas F.

    2011-01-01

    Studies of spatial representation generally focus on flat environments and visual input. However, the world is not flat, and slopes are part of most natural environments. In a series of 4 experiments, we examined whether humans can use a slope as a source of allocentric, directional information for reorientation. A target was hidden in a corner of…

  4. Tom Friedman on Education in the "Flat World"

    Science.gov (United States)

    School Administrator, 2008

    2008-01-01

    In his best-selling book, "The World Is Flat," Thomas Friedman describes that the real world is becoming "flat." He describes how 10 forces are "flattening" the 21st century--making it easier for people in India, China and around the world to compete with Americans and others who had triumphed the century before. This article presents an interview…

  5. On exterior calculus and curvature in piecewise-flat manifolds

    CERN Document Server

    McDonald, Jonathan R; Alsing, Paul M; Gu, Xianfeng D; Wang, Xuping; Yau, Shing-Tung

    2012-01-01

    Simplicial, piecewise-flat discretizations of manifolds provide a clear path towards curvature analysis on discrete geometries and for solutions of PDE's on manifolds of complex topologies. In this manuscript we review and expand on discrete exterior calculus methods using hybrid domains. We then analyze the geometric structure of curvature operators in a piecewise-flat lattice.

  6. On the Picard group of a compact flat projective variety

    NARCIS (Netherlands)

    Michelacakis, NJ

    1996-01-01

    In this note, we describe the Picard group of the class of compact, smooth, flat, projective varieties. In view of Charlap's work and Johnson's characterization, we construct line bundles over such manifolds as the holonomy-invariant elements of the Neron-Severi group of a projective flat torus cove

  7. The Generation of Curved Clathrin Coats from Flat Plaques

    NARCIS (Netherlands)

    Otter, den Wouter K.; Briels, Wim J.

    2011-01-01

    Flat clathrin lattices or ‘plaques’ are commonly believed to be the precursors to clathrin-coated buds and vesicles. The sequence of steps carrying the flat hexagonal lattice into a highly curved polyhedral cage with exactly 12 pentagons remains elusive, however, and the large numbers of disrupted i

  8. Free energy of topologically massive gravity and flat space holography

    OpenAIRE

    Grumiller, Daniel; Merbis, Wout

    2015-01-01

    We calculate the free energy from the on-shell action for topologically massive gravity with negative and vanishing cosmological constant, thereby providing a first principles derivation of the free energy of BTZ black holes and flat space cosmologies. We summarize related recent checks of flat space holography.

  9. Temporal bed level variations in the Yangtze tidal flats (abstract)

    NARCIS (Netherlands)

    Yan, H.; Van Prooijen, B.C.

    2013-01-01

    The Yangtze River is one of the largest rivers in the world and the longest one in Asia. Its estuary forms an important entrance for shipping, but is also a key ecological system. Especially the inter-tidal flats are valuable habitats. The health and integrity of the estuarine tidal flat are however

  10. 75 FR 12981 - Eligibility for Commercial Flats Failing Deflection

    Science.gov (United States)

    2010-03-18

    ... May 2009 was published in the Federal Register (74 FR 15380-15384) on April 6, 2009. The final rule... being drawn into the Flats Sequencing Sortation (FSS) workflow and possible negative effects on service... changing the design or production of their mailpieces. Flat-size pieces that do not meet...

  11. New face-centered photonic square lattices with flat bands

    CERN Document Server

    Zhang, Yiqi; Li, Changbiao; Zhang, Zhaoyang; Zhang, Yanpeng; Xiao, Min

    2016-01-01

    We report two new classes of face-centered photonic square lattices with flat bands which we call the Lieb-I and the Lieb-II lattices. There are 5 and 7 sites in the corresponding unit cells of the simplest Lieb-I and Lieb-II lattices, respectively. The number of flat bands $m$ in the new Lieb lattices is related to the number of sites $N$ in the unit cell by $m=(N-1)/2$. Physical properties of the lattices with even and odd number of flat bands are different. We also consider localization of light in such Lieb lattices. If the input beam excites the flat-band mode, it will not diffract during propagation, owing to the strong localization in the flat-band mode. For the Lieb-II lattice, we also find that the beam will oscillate and still not diffract during propagation, because of the intrinsic oscillating properties of certain flat-band modes. The period of oscillation is determined by the energy difference between the two flat bands. This study provides a new platform for the investigation of flat-band modes...

  12. Teach us atom structure

    International Nuclear Information System (INIS)

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  13. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  14. In situ atomic scale mechanical microscopy discovering the atomistic mechanisms of plasticity in nano-single crystals and grain rotation in polycrystalline metals

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xiaodong, E-mail: xdhan@bjut.edu.cn [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology (China); Wang, Lihua; Yue, Yonghai [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology (China); Zhang, Ze, E-mail: zezhang@zju.edu.cn [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology (China); Department of Materials Science, National Key Lab of Silicon Materials, Zhejiang University (China)

    2015-04-15

    In this review, we briefly introduce our in situ atomic-scale mechanical experimental technique (ASMET) for transmission electron microscopy (TEM), which can observe the atomic-scale deformation dynamics of materials. This in situ mechanical testing technique allows the deformation of TEM samples through a simultaneous double-tilt function, making atomic-scale mechanical microscopy feasible. This methodology is generally applicable to thin films, nanowires (NWs), tubes and regular TEM samples to allow investigation of the dynamics of mechanically stressed samples at the atomic scale. We show several examples of this technique applied to Pt and Cu single/polycrystalline specimens. The in situ atomic-scale observation revealed that when the feature size of these materials approaches the nano-scale, they often exhibit “unusual” deformation behaviours compared to their bulk counterparts. For example, in Cu single-crystalline NWs, the elastic–plastic transition is size-dependent. An ultra-large elastic strain of 7.2%, which approaches the theoretical elasticity limit, can be achieved as the diameter of the NWs decreases to ∼6 nm. The crossover plasticity transition from full dislocations to partial dislocations and twins was also discovered as the diameter of the single-crystalline Cu NWs decreased. For Pt nanocrystals (NC), the long-standing uncertainties of atomic-scale plastic deformation mechanisms in NC materials (grain size G less than 15 nm) were clarified. For larger grains with G<∼10 nm, we frequently observed movements and interactions of cross-grain full dislocations. For G between 6 and 10 nm, stacking faults resulting from partial dislocations become more frequent. For G<∼6 nm, the plasticity mechanism transforms from a mode of cross-grain dislocation to a collective grain rotation mechanism. This grain rotation process is mediated by grain boundary (GB) dislocations with the assistance of GB diffusion and shuffling. These in situ atomic

  15. In situ atomic scale mechanical microscopy discovering the atomistic mechanisms of plasticity in nano-single crystals and grain rotation in polycrystalline metals

    International Nuclear Information System (INIS)

    In this review, we briefly introduce our in situ atomic-scale mechanical experimental technique (ASMET) for transmission electron microscopy (TEM), which can observe the atomic-scale deformation dynamics of materials. This in situ mechanical testing technique allows the deformation of TEM samples through a simultaneous double-tilt function, making atomic-scale mechanical microscopy feasible. This methodology is generally applicable to thin films, nanowires (NWs), tubes and regular TEM samples to allow investigation of the dynamics of mechanically stressed samples at the atomic scale. We show several examples of this technique applied to Pt and Cu single/polycrystalline specimens. The in situ atomic-scale observation revealed that when the feature size of these materials approaches the nano-scale, they often exhibit “unusual” deformation behaviours compared to their bulk counterparts. For example, in Cu single-crystalline NWs, the elastic–plastic transition is size-dependent. An ultra-large elastic strain of 7.2%, which approaches the theoretical elasticity limit, can be achieved as the diameter of the NWs decreases to ∼6 nm. The crossover plasticity transition from full dislocations to partial dislocations and twins was also discovered as the diameter of the single-crystalline Cu NWs decreased. For Pt nanocrystals (NC), the long-standing uncertainties of atomic-scale plastic deformation mechanisms in NC materials (grain size G less than 15 nm) were clarified. For larger grains with G<∼10 nm, we frequently observed movements and interactions of cross-grain full dislocations. For G between 6 and 10 nm, stacking faults resulting from partial dislocations become more frequent. For G<∼6 nm, the plasticity mechanism transforms from a mode of cross-grain dislocation to a collective grain rotation mechanism. This grain rotation process is mediated by grain boundary (GB) dislocations with the assistance of GB diffusion and shuffling. These in situ atomic

  16. Flat Surface Damage Detection System (FSDDS)

    Science.gov (United States)

    Williams, Martha; Lewis, Mark; Gibson, Tracy; Lane, John; Medelius, Pedro; Snyder, Sarah; Ciarlariello, Dan; Parks, Steve; Carrejo, Danny; Rojdev, Kristina

    2013-01-01

    The Flat Surface Damage Detection system (FSDDS} is a sensory system that is capable of detecting impact damages to surfaces utilizing a novel sensor system. This system will provide the ability to monitor the integrity of an inflatable habitat during in situ system health monitoring. The system consists of three main custom designed subsystems: the multi-layer sensing panel, the embedded monitoring system, and the graphical user interface (GUI). The GUI LABVIEW software uses a custom developed damage detection algorithm to determine the damage location based on the sequence of broken sensing lines. It estimates the damage size, the maximum depth, and plots the damage location on a graph. Successfully demonstrated as a stand alone technology during 2011 D-RATS. Software modification also allowed for communication with HDU avionics crew display which was demonstrated remotely (KSC to JSC} during 2012 integration testing. Integrated FSDDS system and stand alone multi-panel systems were demonstrated remotely and at JSC, Mission Operations Test using Space Network Research Federation (SNRF} network in 2012. FY13, FSDDS multi-panel integration with JSC and SNRF network Technology can allow for integration with other complementary damage detection systems.

  17. Prunus hybrids rootstocks for flat peach

    Directory of Open Access Journals (Sweden)

    Pilar Legua

    2012-02-01

    Full Text Available Peach (Prunus persica L. is the most important stone fruit tree grown in Spain and is the second most important fruit crop in Europe. The influence of eight Prunus rootstocks (GF-677, Krymsk® 86, PADAC 97-36, PADAC 99-05, PADAC 9912-03, PADAC 0024-01, PAC 0021-01 and PAC 0022-01 on vigor, yield and fruit quality traits of 'UFO 3' flat peach cultivar was studied. The highest trunk cross sectional area was exhibited by GF-677 and the lowest by PADAC 99-05, while intermediate values were found on the other rootstocks. The highest yield efficiency was found on PADAC 99-05, PAC 0021-01, PAC 0022-01 and PADAC 0024-01 and the lowest was shown on Krymsk® 86. The fruit quality parameters measured were color, fruit and stone weights, equatorial diameter, pulp thickness, pulp yield, firmness, pH, soluble solids content and titratable acidity. 'UFO 3' grafted on GF-677 resulted in the largest fruit weight, while the smallest was on PADAC 99-05. Fruits of 'UFO 3' showed a tendency to have higher firmness, higher red colored skin and RI when grafted on PADAC 99-05.

  18. Seismic hazard analysis at Rocky Flats Plant

    International Nuclear Information System (INIS)

    A probabilistic seismic hazard analysis is being conducted for the DOE Rocky Flats Plan, Jefferson County, Colorado. This is part of the overall review of the seismic exposure to facilities being conducted by DOE. The study has four major elements. (1) The historical seismicity in Colorado is being reviewed and synthesized to estimate historical rates of earthquake activity in the region of the site. (2) The geologic and tectonic evidence in Colorado and along the Front Range is being reviewed to determine appropriate seismic zones, potentially active faults, and constraints on fault slip rates. (3) Earthquake ground motion equations are being derived based on seismological knowledge of the earth's crust. Site specific soil amplification factors are also being developed using on-site shear wave velocity measurements. (4) The probability of exceedence of various seismic ground motion levels is being calculated based on the inputs developed on tectonic sources, faults, ground motion, and soil amplification. Deterministic ground motion estimates are also being made. This study is a state-of-the-art analysis of seismic hazard. It incorporates uncertainties in the major aspects governing seismic hazard, and has a documented basis founded on solid data interpretations for the ranges of inputs used. The results will be a valid basis on which to evaluate plant structures, equipment, and components for seismic effects

  19. Electrohydrodynamic Printing on Flat and Uneven Surfaces

    Science.gov (United States)

    Maktabi, Sepehr; Chiarot, Paul

    2015-11-01

    In electronics manufacturing, the need for high resolution patterns can be met by generating fine droplets using materials printing techniques. Other desirable features are high print speeds, high frequency droplet generation, and large stand-off distances. In this work, an array of emission modes for a tunable electrohydrodynamic (EHD) printing method is reported. Among these, the promising microdripping mode generated droplets an order of magnitude smaller than the nozzle's inner diameter at a frequency range of 2-8 kHz. This method is applied to print organic resistors using the conductive ink poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS). They were printed on flat and uneven substrates at speeds up to 50 mm/s. They had a width from 50 to 500 um and resistance from 1 to 70 Ω/um. The effect of supply flow rate, applied voltage, stand-off distance, and target substrate material properties with respect to droplet generation frequency was investigated. Experimental results reveal that frequency increases nonlinearly with the applied voltage, which is strongly influenced by the non-Newtonian shear thinning effect of PEDOT:PSS. The topology of a 3-dimensional substrate is shown to have a significant effect on the structure and function of a printed resistor.

  20. Atomic phase diagram

    Institute of Scientific and Technical Information of China (English)

    LI Shichun

    2004-01-01

    Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.