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Sample records for quasi-two-dimensional molecular conductor

  1. Electron and electron-phonon effects in quasi-two-dimensional molecular conductor theta-(BETS) sub 4 HgBr sub 4 (C sub 6 H sub 5 Cl): optical investigations at 300-15 K

    CERN Document Server

    Vlasova, R M; Petrov, B V; Semkin, N D; Zhilyaeva, E I; Bogdanova, O A; Lyubovskaya, R N; Graja, A

    2002-01-01

    One studied the polarized spectra of reflection and spectra of optical transmission of theta-(BETS) sub 4 HgBr sub 4 (C sub 6 H sub 5 Cl) quasi-two-dimensional molecular conductor within 700-6500 cm sup - sup 1 range under 300-15 K temperatures and within 9000-40000 cm sup - sup 1 under 300 K for two principal directions within crystal plane parallel to conducting layers of BETS molecules. Under 300 K within IR region the spectra are characterized by the intensive essential peculiarities (1200-1400 cm sup - sup 1) caused by electron-oscillation coupling (EOC). At temperature drop within 180-80 K range one observes in the spectra a Lorentz term with omega sub t = 2900 cm sup - sup 1 and three extra bands within 800-1180 cm sup - sup 1 region caused by EOC. The derived results are indicative of unstable structural distortions along two principal directions in a crystal followed by formation of a charge density comparable wave

  2. Origin of anomalous magnetic breakdown frequencies in quasi-two-dimensional organic conductors

    Science.gov (United States)

    Sandhu, P. S.; Kim, Ju H.; Brooks, J. S.

    1997-11-01

    We investigate the origin of anomalous magnetic breakdown frequencies in the de Haas-van Alphen (dHvA) effect in quasi-two-dimensional organic conductors such as α-(BEDT-TTF)2KHg(SCN)4 and κ-(BEDT-TTF)2Cu(NCS)2. A tight-binding model based on their realistic band structure is constructed and solved numerically to compute the field dependence of the magnetization. The present model provides a natural description for the phenomenon of magnetic breakdown between coexisting closed and open Fermi surfaces and accounts for the experimentally observed frequencies that are forbidden in the semiclassical picture. We find that the appearance of these anomalous frequencies in the dHvA signal is a quantum-mechanical effect which arises from differences in field dependence of the states in the two partially occupied bands near the Fermi level.

  3. Magnetic breakdown phenomenon in quasi-two-dimensional organic conductors: A quantum model inspired by a realistic band structure

    Science.gov (United States)

    Kim, Ju H.; Han, S. Y.; Brooks, J. S.

    1999-08-01

    We investigate the phenomenon of magnetic breakdown in quasi-two-dimensional organic conductors such as α-(ET)2KHg(SCN)4 and κ-(ET)2Cu(NCS)2 by constructing a tight-binding model based on a realistic band structure which is derived from the crystallographic data. We solve the model numerically to compute the magnetic field dependence of the magnetization and show that the present model accounts naturally for the experimentally observed magnetization oscillation frequencies that are forbidden in the semiclassical picture. The computed values of the fundamental and magnetic breakdown frequencies with no adjustable parameters are close to the experimentally measured values. For completeness, we carry out the computation for both canonical (fixed number of particles) and grand canonical (fixed chemical potential) ensembles, and show that the forbidden frequencies appear in both cases. Hence, the appearance of anomalous frequencies in the de Haas-van Alphen effect has a quantum-mechanical origin and arises from the interplay of electronic states from two partially occupied bands near the Fermi energy as a function of magnetic field. We also compute the temperature dependence of the magnetization and apply ad hoc the Lifshitz-Kosevich analysis to the amplitudes of the Fourier components at moderately high temperatures. This yields effective mass values for α-(ET)2KHg(SCN)4 in good agreement with experimental values.

  4. Drude weight in quasi-two-dimensional organic conductors close to the Mott transition: Optical studies of the bandwidth, filling and temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Drichko, Natalia [Ioffe Physico-Technical Institute, Polytekhnicheskaya 26, 194021 St. Petersburg (Russian Federation); 1. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany)], E-mail: drichko@pi1.physik.uni-stuttgart.de; Dumm, Michael; Faltermeier, Daniel; Dressel, Martin [1. Physikalisches Institut, Universitaet Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Merino, Jaime [Dept. de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid (Spain); Greco, Andres [Facultad de Ciencias Exactas Ingenieria y Agrimensura e Instituto de Fisica Rosario (UNR-CONICET), Rosario (Argentina)

    2007-09-01

    We explore the effects of electronic correlations in quasi-two-dimensional BEDT-TTF-based organic conductors with half, quarter and 1/5-filled bands. Close to the Mott transition but still on the metallic side, quasiparticles are observed in the 1/2-filled systems only at temperatures well below 100 K, with a considerable growth of the Drude-like contribution. In contrast, the 1/4-filled conductors show a zero-frequency conduction peak already at room temperature which increases slightly upon cooling. Basically no change with temperature is observed for the Drude contribution of the 1/5-filled compound. Optical studies allow us to investigate the formation of quasiparticles at low temperature for systems of different filling. The strongest effect is observed in 1/2-filled compounds, it becomes weaker in 1/4 filled, while in the 1/5-filled compound no change of the Dude-peak on temperature is seen.

  5. Non-Linear Conduction in the Density Wave State of Quasi-Two Dimensional Organic Conductor α-(BEDT-TTF)2KHg(SCN)4

    Science.gov (United States)

    Fujita, Toshiyuki; Sasaki, Takahiko; Yoneyama, Naoki; Kobayashi, Norio

    2004-06-01

    Current-voltage characteristics are measured in the quasi-two dimensional organic conductor α-(BEDT-TTF)2KHg(SCN)4 at temperatures down to 0.5 K and in the magnetic field up to 25 T. The non-linear conduction with a threshold electric field is found in the density wave state. The features of threshold electric field obtained in the low magnetic field region are explained by the unconventional charge density wave model. In the high magnetic field region, where the Shubnikov-de Haas oscillations appear, the current-voltage characteristics reveal that the density wave state synchronizes with the filling of the electron on the Landau level and continues even above a kink field 23 T.

  6. Magnetic ground state of quasi-two-dimensional organic conductor, τ-(EDO-S,S-DMEDT-TTF)2(AuCl2)1+y

    Science.gov (United States)

    Nakanishi, T.; Yasuzuka, S.; Yoshino, H.; Fujiwara, H.; Sugimoto, T.; Nishio, Y.; Kajita, K.; Anyfantis, G. A.; Papavassiliou, G. C.; Murata, K.

    2006-11-01

    To understand the interplay between transport and magnetic properties, quasi-two-dimensional (Q2D) organic conductor τ-(EDO-S,S-DMEDTTTF)2(AuCl2)1+y was studied by measurements of electric resistivity ( ρa, ρc), magnetoresistance (MR), susceptibility (χ) and specific heat (C) in the temperature region between 1 K and 300 K. In spite of the fact that the drastic changes were observed in ρa, ρc, MR and χ at TC = 20 K, no anomaly was seen in C. The concentration of spins estimated from M-H curve is about 360 ppm, which is difficult to detect anomaly in C. These data suggest that the number of spins is very small in the ground state like spin-glass system.

  7. The use of experimental data in constraining the tight-binding band parameters of quasi-two-dimensional organic molecular metals: application to α-(BEDT- TTF)2KHg(SCN)4

    Science.gov (United States)

    Harrison, N.; Rzepniewski, E.; Singleton, J.; Gee, P. J.; Honold, M. M.; Day, P.; Kurmoo, M.

    1999-09-01

    Whilst tight-binding bandstructure calculations are very successful in describing the Fermi-surface configuration in many quasi-two-dimensional organic molecular metals, the detailed topology of the predicted Fermi surface often differs from that measured in experiments. This is very significant when, for example, the formation of a density-wave state depends critically on details of the nesting of Fermi-surface sheets. These differences between theory and experiment probably result from the limited accuracy to which the icons/Journals/Common/pi" ALT="pi" ALIGN="TOP"/>-orbitals of the component molecules (which give rise to the transfer integrals of the tight-binding bandstructure) are known. In order to surmount this problem, we have derived a method whereby the transfer integrals within a tight-binding bandstructure model are adjusted until the detailed Fermi-surface topology is in good agreement with a wide variety of experimental data. The method is applied to the charge-transfer salt icons/Journals/Common/alpha" ALT="alpha" ALIGN="TOP"/>-(BEDT-TTF)2KHg(SCN)4, the Fermi surface of which has been the source of much speculation in recent years. The Fermi surface obtained differs in detail from previous bandstructure calculation findings. In particular, the quasi-one-dimensional component of the Fermi surface is more strongly warped. This implies that upon nesting of these sheets, significant parts of the quasi-one-dimensional sheets remain, leading to a complicated Fermi-surface topology within the low-temperature, low-magnetic-field phase. In contrast to previous models of this phase, the model for the reconstructed Fermi surface in this work can explain virtually all of the current experimental observations in a consistent manner.

  8. Quasi-Two-Dimensional Magnetism in Co-Based Shandites

    Science.gov (United States)

    Kassem, Mohamed A.; Tabata, Yoshikazu; Waki, Takeshi; Nakamura, Hiroyuki

    2016-06-01

    We report quasi-two-dimensional (Q2D) itinerant electron magnetism in the layered Co-based shandites. Comprehensive magnetization measurements were performed using single crystals of Co3Sn2-xInxS2 (0 ≤ x ≤ 2) and Co3-yFeySn2S2 (0 ≤ y ≤ 0.5). The magnetic parameters of both systems; the Curie temperature TC, effective moment peff and spontaneous moment ps; exhibit almost identical variations against the In- and Fe-concentrations, indicating significance of the electron count on the magnetism in the Co-based shandite. The ferromagnetic-nonmagnetic quantum phase transition is found around xc ˜ 0.8. Analysis based on the extended Q2D spin fluctuation theory clearly reveals the highly Q2D itinerant electron character of the ferromagnetism in the Co-based shandites.

  9. Antiferromagnetic fluctuations in a quasi-two-dimensional organic superconductor detected by Raman spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Drichko, Natalia; Hackl, Rudi; Schlueter, John A.

    2015-10-15

    Using Raman scattering, the quasi-two-dimensional organic superconductor kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br (T-c = 11.8 K) and the related antiferromagnet kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl are studied. Raman scattering provides unique spectroscopic information about magnetic degrees of freedom that has been otherwise unavailable on such organic conductors. Below T = 200 K a broad band at about 500 cm(-1) develops in both compounds. We identify this band with two-magnon excitation. The position and the temperature dependence of the spectral weight are similar in the antiferromagnet and in the metallic Fermi liquid. We conclude that antiferromagnetic correlations are similarly present in the magnetic insulator and the Fermi-liquid state of the superconductor.

  10. Kinetic Theory of a Confined Quasi-Two-Dimensional Gas of Hard Spheres

    Directory of Open Access Journals (Sweden)

    J. Javier Brey

    2017-02-01

    Full Text Available The dynamics of a system of hard spheres enclosed between two parallel plates separated a distance smaller than two particle diameters is described at the level of kinetic theory. The interest focuses on the behavior of the quasi-two-dimensional fluid seen when looking at the system from above or below. In the first part, a collisional model for the effective two-dimensional dynamics is analyzed. Although it is able to describe quite well the homogeneous evolution observed in the experiments, it is shown that it fails to predict the existence of non-equilibrium phase transitions, and in particular, the bimodal regime exhibited by the real system. A critical revision analysis of the model is presented , and as a starting point to get a more accurate description, the Boltzmann equation for the quasi-two-dimensional gas has been derived. In the elastic case, the solutions of the equation verify an H-theorem implying a monotonic tendency to a non-uniform steady state. As an example of application of the kinetic equation, here the evolution equations for the vertical and horizontal temperatures of the system are derived in the homogeneous approximation, and the results compared with molecular dynamics simulation results.

  11. Ordered quasi-two-dimensional structure of nanoparticles in semiflexible ring polymer brushes under compression

    Science.gov (United States)

    Hua, Yunfeng; Deng, Zhenyu; Jiang, Yangwei; Zhang, Linxi

    2017-06-01

    Molecular dynamics simulations of a coarse-grained bead-spring model of ring polymer brushes under compression are presented. Flexible polymer brushes are always disordered during compression, whereas semiflexible polymer brushes tend to be ordered under sufficiently strong compression. Further, the polymer monomer density of the semiflexible polymer brush is very high near the brush surface, inducing a peak value of the free energy near the surface. Therefore, when nanoparticles are compressed in semiflexible ring polymer brushes, they tend to exhibit a closely packed single-layer structure between the brush surface and the impenetrable wall, and a quasi-two-dimensional ordered structure near the brush surface is formed under strong compression. These findings provide a new approach to designing responsive applications.

  12. Quasi-two-dimensional Dirac fermions and quantum magnetoresistance in LaAgBi$_2$

    OpenAIRE

    Wang, Kefeng; Graf, D.; Petrovic, C.

    2016-01-01

    We report quasi-two-dimensional Dirac fermions and quantum magnetoresistance in LaAgBi$_2$. The band structure shows several narrow bands with nearly linear energy dispersion and Dirac-cone-like points at the Fermi level. The quantum oscillation experiments revealed one quasi-two-dimensional Fermi pocket and another complex pocket with small cyclotron resonant mass. The in-plane transverse magnetoresistance exhibits a crossover at a critical field $B^*$ from semiclassical weak-field $B^2$ dep...

  13. Collective modes of a quasi-two-dimensional Bose condensate in large gas parameter regime

    Indian Academy of Sciences (India)

    S R Mishra; S P Ram; Arup Banerjee

    2007-06-01

    We have theoretically studied the collective modes of a quasi-two-dimensional (Q2D) Bose condensate in the large gas parameter regime by using a formalism which treats the interaction energy beyond the mean-field approximation. The results show that incorporation of this higher order term leads to significant modifications in the mode frequencies.

  14. Quasi-particle properties in a quasi-two-dimensional electron liquid

    Indian Academy of Sciences (India)

    R Asgari; B Tanatar

    2008-02-01

    We consider the quasi-particle properties such as the effective mass and spin susceptibility of quasi-two-dimensional electron systems. The finite quantum well width effects are incorporated into the local-field factors that describe the charge and spin correlations. We employ the Fermi-hypernetted chain formalism in conjunction with fluctuation-dissipation theorem to obtain the local-field factors. Our results are in good agreement with recent experiments.

  15. Three-body recombination in a quasi-two-dimensional quantum gas

    Science.gov (United States)

    Huang, Bo; Zenesini, Alessandro; Grimm, Rudolf

    2016-05-01

    Quantum three-body recombination in three-dimensional systems is influenced by a series of weakly bound trimers known as Efimov states, which are induced by short-range interactions and exhibit a discrete scaling symmetry. On the other hand, two-dimensional systems with contact interactions are characterized by continuous scale invariance and support no Efimov physics. This raises questions about the behaviour of three-body recombination in the transition from three to two dimensions. We use ultracold caesium atoms trapped in anisotropic potentials formed by a pair of counter-propagating laser beams to experimentally investigate three-body recombination in quasi-two-dimensional systems with tunable confinement and tunable interactions. In our recent experiments, we observed a smooth transition of the three-body recombination rate coefficient from a three-dimensional to a deeply quasi-two-dimensional system. A comparison between the results obtained near two Feshbach resonances indicates a universal behaviour of three-body recombination in the quasi-two-dimensional regime. Austrian Science Fund FWF within project P23106.

  16. Negative static permittivity and violation of Kramers-Kronig relations in quasi-two-dimensional crystals

    Science.gov (United States)

    Nazarov, V. U.

    2015-10-01

    We investigate the wave vector and frequency-dependent screening of the electric field in atomically thin (quasi-two-dimensional) crystals. For graphene and hexagonal boron nitride we find that, above a critical wave vector qc, the static permittivity ɛ (q >qc,ω =0 ) becomes negative and the Kramers-Kronig relations do not hold for ɛ (q >qc,ω ) . Thus, in quasi-two-dimensional crystals, we reveal the physical confirmation of a proposition put forward decades ago [D. A. Kirzhnits, Sov. Phys. Usp. 19, 530 (1976), 10.1070/PU1976v019n06ABEH005268], allowing for the breakdown of Kramers-Kronig relations and for negative static permittivity. In the vicinity of the critical wave vector, we find a giant growth of the permittivity. Our results, obtained in the ab initio calculations using both the random-phase approximation and the adiabatic time-dependent local-density approximation, and further confirmed with a simple slab model, allow us to argue that the above properties, being exceptional in the three-dimensional case, are common to quasi-two-dimensional systems.

  17. Quasi-two-dimensional complex plasma containing spherical particles and their binary agglomerates

    CERN Document Server

    Chaudhuri, M; Nosenko, V; Thomas, H M

    2015-01-01

    A new type of quasi-two-dimensional complex plasma system was observed which consisted of monodisperse microspheres and their binary agglomerations (dimers). The particles and their dimers levitated in a plasma sheath at slightly different heights and formed two distinct sublayers. The sys- tem did not crystallize and may be characterized as disordered solid. The dimers were identified based on their characteristic appearance in defocused images, i.e., rotating interference fringe pat- terns. The in-plane and inter-plane particle separations exhibit nonmonotonic dependence on the discharge pressure which agrees well with theoretical predictions.

  18. Block copolymer micelle coronas as quasi-two-dimensional dilute or semidilute polymer solutions

    DEFF Research Database (Denmark)

    Svaneborg, C.; Pedersen, J.S.

    2001-01-01

    Chain-chain interactions in a corona of polymers tethered to a spherical core under good solvent conditions are studied using Monte Carlo simulations. The total scattering function of the corona as well as different partial contributions are sampled. By combining the different contributions...... in a self-consistent approach, it is demonstrated that the corona can be regarded as a quasi-two-dimensional polymer solution, with a concentration dependence analogous to that of an ordinary polymer solution. Scattering due to the corona profile and density fluctuation correlations are separated...

  19. Characterizing Mixing in a Quasi-Two-Dimensional Flow using Persistent Homology

    Science.gov (United States)

    Tithof, Jeffrey; Kelley, Douglas

    2016-11-01

    Fluid mixing is a tremendously important phenomenon present in numerous physical systems, both natural and human-made. Describing, understanding, and predicting the mixing behavior of fluid flows poses an immense challenge. In this work, we explore the utility of topological data analysis in quantifying fluid mixing. We analyze Eulerian and Lagrangian quantities obtained from a quasi-two-dimensional flow realized by driving a thin layer of fluid with electromagnetic forces. Our analysis employs persistent homology, which offers a unique framework for quantifying topological features associated with connectivity in the fluid flow. Preliminary results suggest that this topological approach offers new physical insight, complementing existing methods for quantifying fluid mixing.

  20. Slow dynamics in a quasi-two-dimensional binary complex plasma

    CERN Document Server

    Du, Cheng-Ran; Thomas, Hubertus M; Morfill, Gregor E; Ivlev, Alexei V

    2016-01-01

    Slow dynamics in an amorphous quasi-two-dimensional complex plasma, comprised of microparticles of two different sizes, was studied experimentally. The motion of individual particles was observed using video microscopy, and the self part of the intermediate scattering function as well as the mean-squared particle displacement was calculated. The long-time structural relaxation reveals the characteristic behavior near the glass transition. Our results suggest that binary complex plasmas can be an excellent model system to study slow dynamics in classical supercooled fluids.

  1. Hall Conductivity in a Quasi-Two-Dimensional Disordered Electron System

    Institute of Scientific and Technical Information of China (English)

    YANG Yong-Hong; WANG Yong-Gang; LIU Mei

    2002-01-01

    By making use of the diagrammatic techniques in perturbation theory,we have investigated the Hall effect in a quasi-two-dimensional disordered electron system.In the weakly localized regime,the analytical expression for quantum correction to Hall conductivity has been obtained using the Kubo formalism and quasiclassical approximation.The relevant dimensional crossover behavior from three dimensions to two dimensions with decreasing the interlayer hopping energy is discussed.The quantum interference effect is shown to have a vanishing correction t,o the Hall coefficient.

  2. An intrinsic growth instability in isotropic materials leads to quasi-two-dimensional nanoplatelets

    Science.gov (United States)

    Riedinger, Andreas; Ott, Florian D.; Mule, Aniket; Mazzotti, Sergio; Knüsel, Philippe N.; Kress, Stephan J. P.; Prins, Ferry; Erwin, Steven C.; Norris, David J.

    2017-07-01

    Colloidal nanoplatelets are atomically flat, quasi-two-dimensional sheets of semiconductor that can exhibit efficient, spectrally pure fluorescence. Despite intense interest in their properties, the mechanism behind their highly anisotropic shape and precise atomic-scale thickness remains unclear, and even counter-intuitive for commonly studied nanoplatelets that arise from isotropic crystal structures (such as zincblende CdSe and lead halide perovskites). Here we show that an intrinsic instability in growth kinetics can lead to such highly anisotropic shapes. By combining experimental results on the synthesis of CdSe nanoplatelets with theory predicting enhanced growth on narrow surface facets, we develop a model that explains nanoplatelet formation as well as observed dependencies on time and temperature. Based on standard concepts of volume, surface and edge energies, the resulting growth instability criterion can be directly applied to other crystalline materials. Thus, knowledge of this previously unknown mechanism for controlling shape at the nanoscale can lead to broader libraries of quasi-two-dimensional materials.

  3. Diffusivity and weak clustering in a quasi-two-dimensional granular gas.

    Science.gov (United States)

    Perera-Burgos, J A; Pérez-Ángel, G; Nahmad-Molinari, Y

    2010-11-01

    We present results from a detailed simulation of a quasi-two-dimensional dissipative granular gas, kept in a noncondensed steady state via vertical shaking over a rough substrate. This gas shows a weak power-law decay in the tails of its pair distribution functions, indicating clustering. This clustering depends monotonically on the dissipation coefficient and disappears when the sphere-sphere collisions are conservative. Clustering is also sensitive to the packing fraction. This gas also displays the standard nonequilibrium characteristics of similar systems, including non-Maxwellian velocity distributions. The diffusion coefficients are calculated over all the conditions of the simulations, and it is found that diluted gases are more diffusive for smaller restitution coefficients.

  4. Hydrodynamics for a model of a confined quasi-two-dimensional granular gas.

    Science.gov (United States)

    Brey, J Javier; Buzón, V; Maynar, P; García de Soria, M I

    2015-05-01

    The hydrodynamic equations for a model of a confined quasi-two-dimensional gas of smooth inelastic hard spheres are derived from the Boltzmann equation for the model, using a generalization of the Chapman-Enskog method. The heat and momentum fluxes are calculated to Navier-Stokes order, and the associated transport coefficients are explicitly determined as functions of the coefficient of normal restitution and the velocity parameter involved in the definition of the model. Also an Euler transport term contributing to the energy transport equation is considered. This term arises from the gradient expansion of the rate of change of the temperature due to the inelasticity of collisions, and it vanishes for elastic systems. The hydrodynamic equations are particularized for the relevant case of a system in the homogeneous steady state. The relationship with previous works is analyzed.

  5. Motility of Escherichia coli in a quasi-two-dimensional porous medium

    Science.gov (United States)

    Sosa-Hernández, Juan Eduardo; Santillán, Moisés; Santana-Solano, Jesús

    2017-03-01

    Bacterial migration through confined spaces is critical for several phenomena, such as biofilm formation, bacterial transport in soils, and bacterial therapy against cancer. In the present work, E. coli (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-two-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98-μ m -diameter spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing several trajectory parameters (instantaneous velocity, turn angle, mean squared displacement, etc.), and contrasting with the results of a random-walk model developed ad hoc, we were able to quantify the effects that different obstacle concentrations have upon bacterial motility.

  6. Dynamical transition in a jammed state of a quasi-two-dimensional foam

    Science.gov (United States)

    Kurita, Rei; Furuta, Yujiro; Yanagisawa, Naoya; Oikawa, Noriko

    2017-06-01

    The states of foam are empirically classified into dry foam and wet foam by the volume fraction of the liquid. Recently, a transition between the dry foam state and the wet foam state has been found by characterizing the bubble shapes [Furuta et al., Sci. Rep. 6, 37506 (2016), 10.1038/srep37506]. In the literature, it is indirectly ascertained that the transition from the dry to the wet form is related to the onset of the rearrangement of the bubbles, namely, the liquid fraction at which the bubbles become able to move to replace their positions. The bubble shape is a static property, and the rearrangement of the bubbles is a dynamic property. Thus, we investigate the relation between the bubble shape transition and the rearrangement event occurring in a collapsing process of the bubbles in a quasi-two-dimensional foam system. The current setup brings a good advantage to observe the above transitions, since the liquid fraction of the foam continuously changes in the system. It is revealed that the rearrangement of the bubbles takes place at the dry-wet transition point where the characteristics of the bubble shape change.

  7. Valence and conduction band structure of the quasi-two-dimensional semiconductor Sn S2

    Science.gov (United States)

    Racke, David A.; Neupane, Mahesh R.; Monti, Oliver L. A.

    2016-02-01

    We present the momentum-resolved photoemission spectroscopy of both the valence and the conduction band region in the quasi-two-dimensional van der Waals-layered indirect band gap semiconductor Sn S2 . Using a combination of angle-resolved ultraviolet photoemission and angle-resolved two-photon photoemission (AR-2PPE) spectroscopy, we characterize the band structure of bulk Sn S2 . Comparison with density functional theory calculations shows excellent quantitative agreement in the valence band region and reveals several localized bands that likely originate from defects such as sulfur vacancies. Evidence for a moderate density of defects is also observed by AR-2PPE in the conduction band region, leading to localized bands not present in the computational results. The energetic structure and dispersion of the conduction bands is captured well by the computational treatment, with some quantitative discrepancies remaining. Our results provide a broader understanding of the electronic structure of Sn S2 in particular and van der Waals-layered semiconductors in general.

  8. General solution of the Dirac equation for quasi-two-dimensional electrons

    Energy Technology Data Exchange (ETDEWEB)

    Eremko, Alexander, E-mail: eremko@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Str., 14-b, Kyiv, 03680 (Ukraine); Brizhik, Larissa, E-mail: brizhik@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Str., 14-b, Kyiv, 03680 (Ukraine); Loktev, Vadim, E-mail: vloktev@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Str., 14-b, Kyiv, 03680 (Ukraine); National Technical University of Ukraine “KPI”, Peremohy av., 37, Kyiv, 03056 (Ukraine)

    2016-06-15

    The general solution of the Dirac equation for quasi-two-dimensional electrons confined in an asymmetric quantum well, is found. The energy spectrum of such a system is exactly calculated using special unitary operator and is shown to depend on the electron spin polarization. This solution contains free parameters, whose variation continuously transforms one known particular solution into another. As an example, two different cases are considered in detail: electron in a deep and in a strongly asymmetric shallow quantum well. The effective mass renormalized by relativistic corrections and Bychkov–Rashba coefficients are analytically obtained for both cases. It is demonstrated that the general solution transforms to the particular solutions, found previously (Eremko et al., 2015) with the use of spin invariants. The general solution allows to establish conditions at which a specific (accompanied or non-accompanied by Rashba splitting) spin state can be realized. These results can prompt the ways to control the spin degree of freedom via the synthesis of spintronic heterostructures with the required properties.

  9. Experimental Observation of Exact Coherent Structures in a Weakly Turbulent Quasi-Two-Dimensional Flow

    Science.gov (United States)

    Suri, Balachandra; Tithof, Jeffrey; Pallantla, Ravi Kumar; Grigoriev, Roman; Schatz, Michael

    2015-11-01

    The dynamical systems approach to fluid turbulence relies on understanding the role of unstable, non-chaotic solutions - such as equilibria, traveling waves, and periodic orbits - of the Navier-Stokes equations. These solutions, called Exact Coherent Structures, exist in the same parameter regime as turbulence, but being unstable, are observed in experiments only as short transients. In this talk, we present experimental evidence for the existence and dynamical relevance of unstable equilibria in a weakly turbulent quasi-two-dimensional (Q2D) Kolmogorov flow. In the experiment, this Q2D flow is generated in an electromagnetically driven shallow layer of electrolyte. The numerical simulations, however, use a strictly 2D model which incorporates the effects of the finite thickness of the fluid layer in the experiment. During its evolution, there are instances when the dynamics of a weakly turbulent flow slow down, rather dramatically. Using experimental flow fields from such instances, and by means of a Newton-Solver, we numerically compute several unstable equilibria. Additionally, using numerical simulations, we show that the dynamics of a turbulent flow in the neighbourhood of an equilibrium are accurately described by the unstable manifold of the equilibrium. This work is supported in part by the National Science Foundation under grants CBET-0900018, and CMMI-1234436.

  10. Vibrational properties of quasi-two-dimensional colloidal glasses with varying interparticle attraction.

    Science.gov (United States)

    Gratale, Matthew D; Ma, Xiaoguang; Davidson, Zoey S; Still, Tim; Habdas, Piotr; Yodh, A G

    2016-10-01

    We measure the vibrational modes and particle dynamics of quasi-two-dimensional colloidal glasses as a function of interparticle interaction strength. The interparticle attractions are controlled via a temperature-tunable depletion interaction. Specifically, the interparticle attraction energy is increased gradually from a very small value (nearly hard-sphere) to moderate strength (∼4k_{B}T), and the variation of colloidal particle dynamics and vibrations are concurrently probed. The particle dynamics slow monotonically with increasing attraction strength, and the particle motions saturate for strengths greater than ∼2k_{B}T, i.e., as the system evolves from a nearly repulsive glass to an attractive glass. The shape of the phonon density of states is revealed to change with increasing attraction strength, and the number of low-frequency modes exhibits a crossover for glasses with weak compared to strong interparticle attraction at a threshold of ∼2k_{B}T. This variation in the properties of the low-frequency vibrational modes suggests a new means for distinguishing between repulsive and attractive glass states.

  11. Anomalous metallic state in quasi-two-dimensional BaNiS2

    Science.gov (United States)

    Santos-Cottin, David; Gauzzi, Andrea; Verseils, Marine; Baptiste, Benoit; Feve, Gwendal; Freulon, Vincent; Plaçais, Bernard; Casula, Michele; Klein, Yannick

    2016-03-01

    We report on a systematic study of the thermodynamic, electronic, and charge transport properties of high-quality single crystals of BaNiS2, the metallic end member of the quasi-two-dimensional BaCo1 -xNixS2 system characterized by a metal-insulator transition at xc r=0.22 . Our analysis of magnetoresistivity and specific heat data consistently suggests a picture of compensated semimetal with two hole bands and one electron band, where electron-phonon scattering dominates charge transport and the minority holes exhibit, below ˜100 K, a very large mobility, μh˜15000 cm2V-1s-1 , which is explained by a Dirac-like band. Evidence of unconventional metallic properties is given by an intriguing crossover of the resistivity from a Bloch-Grüneisen regime to a linear-T regime occurring at 2 K and by a strong linear term in the paramagnetic susceptibility above 100 K. We discuss the possibility that these anomalies reflect a departure from conventional Fermi-liquid properties in presence of short-range AF fluctuations and of a large Hund coupling.

  12. Three-dimensional magnetic interactions in quasi-two-dimensional PdAs2O6

    Science.gov (United States)

    Zhao, Z. Y.; Wu, Y.; Cao, H. B.; Zhou, H. D.; Yan, J.-Q.

    2017-06-01

    Millimeter-sized PdAs2O6 single crystals are grown using the vapor transport technique. The magnetic order at {{T}\\text{N}}=140 K is studied by measuring magnetic properties, specific heat, and neutron single crystal diffraction. The anisotropic magnetic susceptibility and a metamagnetic transition observed in magnetic fields above 20 kOe suggest that the magnetic moment lies in the ab plane, consistent with the magnetic structure determined by neutron single crystal diffraction. Below 140 K, Pd2+ ions order ferromagnetically in the ab plane but antiferromagnetically along the crystallographic c axis. The ordered moment is refined to be 2.09(2) {μ\\text{B}} /Pd2+ using the fitted magnetic form factor of Pd2+ . A weak λ-type anomaly around T N was observed in specific heat and the magnetic entropy change across T N is 1.72 J mol-1 K.This small entropy change and the temperature dependence of the magnetic susceptibility support the presence of short range correlations in a wide temperature range {{T}\\text{N}} 250 K. The comparison with SrRu2O6 suggests that the magnetic interactions in PdAs2O6 are dominated by Pd-(O-\\text{As}\\text{As} -O)-Pd super-superexchange and three dimensional despite the quasi-two-dimensional arrangement of magnetic ions. The comparison with NiAs2O6 suggests that increasing covalency of isostructural compounds is an effective approach to design and to discover new materials with higher magnetic order temperatures in the localized regime.

  13. Protected Fe valence in quasi-two-dimensional α-FeSi2

    Science.gov (United States)

    Miiller, W.; Tomczak, J. M.; Simonson, J. W.; Smith, G.; Kotliar, G.; Aronson, M. C.

    2015-05-01

    We report the first comprehensive study of the high temperature form (α-phase) of iron disilicide. Measurements of the magnetic susceptibility, magnetization, heat capacity and resistivity were performed on well characterized single crystals. With a nominal iron d6 configuration and a quasi-two-dimensional crystal structure that strongly resembles that of LiFeAs, α-FeSi2 is a potential candidate for unconventional superconductivity. Akin to LiFeAs, α-FeSi2 does not develop any magnetic order and we confirm its metallic state down to the lowest temperatures (T = 1.8 K). However, our experiments reveal that paramagnetism and electronic correlation effects in α-FeSi2 are considerably weaker than in the pnictides. Band theory calculations yield small Sommerfeld coefficients of the electronic specific heat γ = Ce/T that are in excellent agreement with experiment. Additionally, realistic many-body calculations further corroborate that quasi-particle mass enhancements are only modest in α-FeSi2. Remarkably, we find that the natural tendency to vacancy formation in the iron sublattice has little influence on the iron valence and the density of states at the Fermi level. Moreover, Mn doping does not significantly change the electronic state of the Fe ion. This suggests that the iron valence is protected against hole doping and indeed the substitution of Co for Fe causes a rigid-band like response of the electronic properties. As a key difference from the pnictides, we identify the smaller inter-iron layer spacing, which causes the active orbitals near the Fermi level to be of a different symmetry in α-FeSi2. This change in orbital character might be responsible for the lack of superconductivity in this system, providing constraints on pairing theories in the iron based pnictides and chalcogenides.

  14. On calculation of quasi-two-dimensional divergence-free projections for visualization of three-dimensional incompressible flows

    OpenAIRE

    Gelfgat, Alexander

    2015-01-01

    A visualization of three-dimensional incompressible flows by divergence-free quasi-two-dimensional projections of the velocity field on three coordinate planes was recently proposed. The projections were calculated using divergence-free Galerkin bases, which resulted in the whole procedure being complicated and CPU-time consuming. Here we propose an alternative way based on the Chorin projection combined with a SIMPLE-like iteration. The approach proposed is much easier in realization, allows...

  15. Mixed valence as a necessary criteria for quasi-two dimensional electron gas in oxide hetero-interfaces

    Science.gov (United States)

    Singh, Vijeta; Pulikkotil, J. J.

    2017-02-01

    The origin of quasi-two dimensional electron gas at the interface of polar-nonpolar oxide hetero-structure, such as LaAlO3/SrTiO3, is debated over electronic reconstruction and defects/disorder models. Common to these models is the partial valence transformation of substrate Ti ions from its equilibrium 4 + state to an itinerant 3 + state. Given that the Hf ions have a lower ionization potential than Ti due to the 4 f orbital screening, one would expect a hetero-interface conductivity in the polar-nonpolar LaAlO3/SrHfO3 system as well. However, our first principles calculations show the converse. Unlike the Ti3+ -Ti4+ valence transition which occur at a nominal energy cost, the barrier energy associated with its isoelectronic Hf3+ -Hf4+ counterpart is very high, hence suppressing the formation of quasi-two dimensional electron gas at LaAlO3/SrHfO3 hetero-interface. These calculations, therefore, emphasize on the propensity of mixed valence at the interface as a necessary condition for an oxide hetero-structure to exihibit quasi two-dimensional electron gas.

  16. Magnetothermopower study of the quasi-two-dimensional organic conductor α-(BEDT-TTF)2KHg(SCN)4

    Science.gov (United States)

    Choi, E. S.; Brooks, J. S.; Qualls, J. S.

    2002-05-01

    We have used a low-frequency magneto-thermopower (MTEP) method to probe the high-magnetic-field ground-state behavior of α-(BEDT-TTF)2KHg(SCN)4 along all three principal crystallographic axes at low temperatures. The thermopower tensor coefficients (Sxx,Syx, and Szz) have been measured to 30 T, beyond the anomalous low-temperature, field-induced transition at 22.5 T. We find a significant anisotropy in the MTEP signal, and also observe large quantum oscillations associated with Landau quantization. The anisotropy indicates that the ground-state properties are clearly driven by mechanisms that occur along specific directions for the in-plane electronic structure. Both transverse and longitudinal magnetothermopower show asymptotic behaviors in the field, which can be explained in terms of magnetic breakdown of compensated closed orbits.

  17. Probing the Scale Invariance of the Inflationary Power Spectrum in Expanding Quasi-Two-Dimensional Dipolar Condensates

    Science.gov (United States)

    Chä, Seok-Yeong; Fischer, Uwe R.

    2017-03-01

    We consider an analogue de Sitter cosmos in an expanding quasi-two-dimensional Bose-Einstein condensate with dominant dipole-dipole interactions between the atoms or molecules in the ultracold gas. It is demonstrated that a hallmark signature of inflationary cosmology, the scale invariance of the power spectrum of inflaton field correlations, experiences strong modifications when, at the initial stage of expansion, the excitation spectrum displays a roton minimum. Dipolar quantum gases thus furnish a viable laboratory tool to experimentally investigate, with well-defined and controllable initial conditions, whether primordial oscillation spectra deviating from Lorentz invariance at trans-Planckian momenta violate standard predictions of inflationary cosmology.

  18. Visualization of three-dimensional incompressible flows by quasi-two-dimensional divergence-free projections in arbitrary flow regions

    Science.gov (United States)

    Gelfgat, Alexander Yu.

    2016-08-01

    A visualization of three-dimensional incompressible flows by divergence-free quasi-two-dimensional projections of the velocity field onto three coordinate planes is revisited. An alternative and more general way to compute the projections is proposed. The approach is based on the Chorin projection combined with a SIMPLE-like iteration. Compared to the previous methodology based on divergence-free Galerkin-Chebyshev bases, this technique, formulated in general curvilinear coordinates, is applicable to any flow region and allows for faster computations. To illustrate this visualization method, examples in Cartesian and spherical coordinates, as well as post-processing of experimental 3D-PTV data, are presented.

  19. PREFACE: International Symposium on Molecular Conductors: Novel Functions of Molecular Conductors under Extreme Conditions (ISMC 2008)

    Science.gov (United States)

    Takahashi, Toshihiro; Suzumura, Yoshikazu

    2008-02-01

    The International Symposium on Molecular Conductors 2008 (ISMC2008) was held as the second international symposium of the project entitled `Novel Functions of Molecular Conductors under Extreme Conditions', which was supported by the Grant-in-aid for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science and Technology in Japan. The project lasted from September 2003 to March 2008, and was completed by this symposium held at Okazaki Conference Center, Institute for Molecular Science, Okazaki, Japan (23-25 July 2008), which about 100 scientists attended. During the symposium, five project teams gave summary talks and exciting talks were given on the topics developed recently not only by the members of the project but also by other scientists including invited speakers from abroad, who are doing active research on molecular conductors. It is expected that papers presented in the symposium will give valuable hints for the next step in the research of this field. Therefore the organizers of this symposium decided to publish this proceedings in order to demonstrate these activities, not only for the local community of the project, but also for the broad society of international scientists who are interested in molecular conductors. The editors, who are also the organizers of this symposium, believe that this proceedings provides a significant and relevant contribution to the field of molecular conductors since it is the first time we have published such a proceedings as an electronic journal. We note that all papers published in this volume of Journal of Physics: Conference Series have been peer reviewed by expert referees. Editors made every effort to satisfy the criterion of a proceedings journal published by IOP Publishing. Toshihiro Takahashi and Yoshikazu Suzumura Editors: Toshihiro Takahashi (Gakushuin University) (Chairman) Kazushi Kanoda (University of Tokyo) Seiichi Kagoshima (University of Tokyo) Takehiko Mori (Tokyo

  20. d-wave superconductivity, antiferromagnetism and spin liquid in quasi-two-dimensional organic superconductors

    Directory of Open Access Journals (Sweden)

    P. Sahebsara

    2006-09-01

    Full Text Available   The self-energy-functional approach is a powerful many-body tool to investigate different broken symmetry phases of strongly correlated electron systems. We use the variational cluster perturbation theory (also called the variational cluster approximation to investigate the interplay between the antiferromagnetism and d-wave superconductivity of κ-(ET2 X conductors. These compounds are described by the so-called dimer Hubbard model, with various values of the on-site repulsion U and diagonal hopping amplitude t. At strong coupling, our zero-temperature calculations show a transition from Néel antiferromagnetism to a spin-liquid phase with no long range order, at around t ~ 0.9. At lower values of U, we find d-wave superconductivity. Taking into account the point group symmetries of the lattice, we find a transition between dx2-y2 and dxy pairing symmetries, the latter happening for smaller values of U.

  1. Spin-Dependent Scattering Effects and Dimensional Crossover in a Quasi-Two-Dimensional Disordered Electron System

    Institute of Scientific and Technical Information of China (English)

    YANG YongHong; WANG YongGang; LIU Mei; WANG Jin

    2002-01-01

    Two kinds of spin-depcndcnt scattering effects (magnetic-iinpurity and spin-orbit scatterings) axe investi-gated theoretically in a quasi-two-dimensional (quasi-2D) disordered electron system. By making use of the diagrammatictechniques in perturbation theory, we have calculated the dc conductivity and magnetoresistance due to weak-localizationeffects, the analytical expressions of them are obtained as functions of the interlayer hopping energy and the charac-teristic times: elastic, inelastic, magnetic and spin-orbit scattering times. The relevant dimensional crossover behaviorfrom 3D to 2D with decreasing the interlayer coupling is discussed, and the condition for the crossover is shown to bedependent on the aforementioned scattering times. At low temperature there exists a spin-dcpendent-scattering-induccddimensional crossover in this system.

  2. On calculation of quasi-two-dimensional divergence-free projections for visualization of three-dimensional incompressible flows

    CERN Document Server

    Gelfgat, Alexander

    2015-01-01

    A visualization of three-dimensional incompressible flows by divergence-free quasi-two-dimensional projections of the velocity field on three coordinate planes was recently proposed. The projections were calculated using divergence-free Galerkin bases, which resulted in the whole procedure being complicated and CPU-time consuming. Here we propose an alternative way based on the Chorin projection combined with a SIMPLE-like iteration. The approach proposed is much easier in realization, allows for faster computations, and can be generalized for arbitrary curvilinear orthogonal coordinates. To illustrate the visualization method, examples of flow visualization in cylindrical and spherical coordinates, as well as post-processing of experimental 3D-PTV data are presented.

  3. Semi-phenomenological analysis of neutron scattering results for quasi-two dimensional quantum anti-ferromagnet

    Science.gov (United States)

    Sarkar, Subhajit; Chaudhury, Ranjan; Paul, Samir K.

    2017-01-01

    The available results from the inelastic neutron scattering experiment performed on the quasi-two dimensional spin 1/2 anti-ferromagnetic material La2CuO4 have been analysed theoretically. The formalism of ours is based on a semi-classical like treatment involving a model of an ideal gas of mobile vortices and anti-vortices built on the background of the Néel state, using the bipartite classical spin configuration corresponding to an XY-anisotropic Heisenberg anti-ferromagnet on a square lattice. The results for the integrated intensities for our spin 1/2 model corresponding to different temperatures, show occurrence of vigorous unphysical oscillations, when convoluted with a realistic spectral window function. These results indicate failure of the conventional semi-classical theoretical model of ideal vortex/anti-vortex gas arising in the Berezinskii-Kosterlitz-Thouless theory for the low spin magnetic systems. A full fledged quantum mechanical formalism and calculations seem crucial for the understanding of topological excitations in such low spin systems. Furthermore, a severe disagreement is found to occur at finite values of energy transfer between the integrated intensities obtained theoretically from the conventional formalism and those obtained experimentally. This further suggests strongly that the full quantum treatment should also incorporate the interaction between the fragile-magnons and the topological excitations. This is quite plausible in view of the recent work establishing such a process in XXZ quantum ferromagnet on 2D lattice. The high spin XXZ quasi-two dimensional antiferromagnet like MnPS3 however follows the conventional theory quite well.

  4. Near-degeneracy of extended s +dx2-y2 and dx y order parameters in quasi-two-dimensional organic superconductors

    Science.gov (United States)

    Guterding, Daniel; Altmeyer, Michaela; Jeschke, Harald O.; Valentí, Roser

    2016-07-01

    The symmetry of the superconducting order parameter in quasi-two-dimensional bis-ethylenedithio-tetrathiafulvalene (BEDT-TTF) organic superconductors is a subject of ongoing debate. We report ab initio density-functional-theory calculations for a number of organic superconductors containing κ -type layers. Using projective Wannier functions, we derive the parameters of a common low-energy Hamiltonian based on individual BEDT-TTF molecular orbitals. In a random-phase approximation spin-fluctuation approach, we investigate the evolution of the superconducting pairing symmetry within this model, and we point out a phase transition between extended s +dx2-y2 and dx y symmetry. We discuss the origin of the mixed order parameter and the relation between the realistic molecule description and the widely used dimer approximation. Based on our ab initio calculations, we position the investigated materials in the obtained molecule model phase diagram, and we simulate scanning tunneling spectroscopy experiments for selected cases. Our calculations show that many κ -type materials lie close to the phase-transition line between the two pairing symmetry types found in our calculation, possibly explaining the multitude of contradictory experiments in this field.

  5. Short-time dynamics of monomers and dimers in quasi-two-dimensional colloidal mixtures

    Science.gov (United States)

    Sarmiento-Gómez, Erick; Villanueva-Valencia, José Ramón; Herrera-Velarde, Salvador; Ruiz-Santoyo, José Arturo; Santana-Solano, Jesús; Arauz-Lara, José Luis; Castañeda-Priego, Ramón

    2016-07-01

    We report on the short-time dynamics in colloidal mixtures made up of monomers and dimers highly confined between two glass plates. At low concentrations, the experimental measurements of colloidal motion agree well with the solution of the Navier-Stokes equation at low Reynolds numbers; the latter takes into account the increase in the drag force on a colloidal particle due to wall-particle hydrodynamic forces. More importantly, we find that the ratio of the short-time diffusion coefficient of the monomer and that of the center of mass of the dimmer is almost independent of both the dimer molar fraction, xd, and the total packing fraction, ϕ , up to ϕ ≈0.5 . At higher concentrations, this ratio displays a small but systematic increase. A similar physical scenario is observed for the ratio between the parallel and the perpendicular components of the short-time diffusion coefficients of the dimer. This dynamical behavior is corroborated by means of molecular dynamics computer simulations that include explicitly the particle-particle hydrodynamic forces induced by the solvent. Our results suggest that the effects of colloid-colloid hydrodynamic interactions on the short-time diffusion coefficients are almost identical and factorable in both species.

  6. High-field studies of quantum oscillations in quasi-two-dimensional organic metals

    Science.gov (United States)

    Sandhu, Pravindrajit

    The organic metals derived from the molecule BEDT-TTF (or ET for short) are important as model systems for the study of low-dimensional phenomena. These materials are molecular crystals with a low Fermi energy (10--100 meV), high mobility (˜104 cm2/Vs) and highly anisotropic Fermi surfaces. We have conducted experimental studies of ( i) the Shubnikov-de Haas (SdH) effect in pulsed fields up to 50 T and (ii) the de Haas-van Alphen (dHvA) effect in steady fields up to 33 T on alpha - (ET)2 MHg(SCN) 4 (where M = K, Tl and NH4) and kappa - (ET)2 Cu (NCS)2. At these high fields, the wave shape as well as the temperature and field-dependence of the oscillations deviate from the behavior predicted by the standard Lifshitz-Kosevich theory. These measurements reveal the limits of the conventional theory of metals and lay the ground-work for extending the theory to low-dimensional systems. We have also performed extended Huckel tight-binding calculations to model the effects of pressure and uniaxial stress on the electronic band structure of kappa - (ET)2 KHg (SCN)4 and kappa - (ET)2 Cu (NCS)2. The calculated changes in the Fermi surface topology are in excellent agreement with the experimental values determined from SdH measurements. We also report predictions of the effects of uniaxial stress in the transverse directions and discuss the behavior of the effective mass and magnetic breakdown probability. Finally, we have investigated the origin of anomalous magnetic breakdown frequencies in the dHvA effect that are forbidden according to semi-classical theories. We construct a tight-binding model based on the realistic band-structure of the system, which is then solved numerically to compute the field-dependence of the magnetization. This model provides a natural description for the phenomenon of magnetic breakdown between co-existing closed and open Fermi surfaces and accounts for the anomalous frequencies that are observed experimentally. The occurrence of these

  7. Controlled Electronic Transport through Branched Molecular Conductors

    OpenAIRE

    2008-01-01

    Abstract The conductance through a branched conductor placed between two electrodes is analyzed using the Landauer transport formulation within the framework of the single electron, and the tight binding approximations. Terminal side chains are expressed as self energy terms which map the branched conductor onto an effective linear chain Hamiltonian. The effect of uniform side branches on resonant zero-bias conductance is shown to be analytically solvable and particularly simple, w...

  8. Axis and velocity determination for quasi two-dimensional plasma/field structures from Faraday's law: A second look

    Science.gov (United States)

    Sonnerup, Bengt U. Ö.; Denton, Richard E.; Hasegawa, Hiroshi; Swisdak, M.

    2013-05-01

    We re-examine the basic premises of a single-spacecraft data analysis method, developed by Sonnerup and Hasegawa (2005), for determining the axis orientation and proper frame velocity of quasi two-dimensional, quasi-steady structures of magnetic field and plasma. The method, which is based on Faraday's law, makes use of magnetic and electric field data measured by a single spacecraft traversing the structure, although in many circumstances the convection electric field, - v × B, can serve as a proxy for E. It has been used with success for flux ropes observed at the magnetopause but has usually failed to provide acceptable results when applied to real space data from reconnection events as well as to virtual data from numerical MHD simulations of such events. In the present paper, the reasons for these shortcomings are identified, analyzed, and discussed in detail. Certain basic properties of the method are presented in the form of five theorems, the last of which makes use of singular value decomposition to treat the special case where the magnetic variance matrix is non-invertible. These theorems are illustrated using data from analytical models of flux ropes and also from MHD simulations as well as a 2-D kinetic simulation of reconnection. The results make clear that the method requires the presence of a significant, non-removable electric field distribution in the plane transverse to the invariant direction and that it is sensitive to deviations from strict two-dimensionality and strict time stationarity.

  9. Evolution of the vortex state in the BCS-BEC crossover of a quasi two-dimensional superfluid Fermi gas

    Science.gov (United States)

    Luo, Xuebing; Zhou, Kezhao; Zhang, Zhidong

    2016-11-01

    We use the path-integral formalism to investigate the vortex properties of a quasi-two dimensional (2D) Fermi superfluid system trapped in an optical lattice potential. Within the framework of mean-field theory, the cooper pair density, the atom number density, and the vortex core size are calculated from weakly interacting BCS regime to strongly coupled while weakly interacting BEC regime. Numerical results show that the atoms gradually penetrate into the vortex core as the system evolves from BEC to BCS regime. Meanwhile, the presence of the optical lattice allows us to analyze the vortex properties in the crossover from three-dimensional (3D) to 2D case. Furthermore, using a simple re-normalization procedure, we find that the two-body bound state exists only when the interaction is stronger than a critical one denoted by G c which is obtained as a function of the lattice potential’s parameter. Finally, we investigate the vortex core size and find that it grows with increasing interaction strength. In particular, by analyzing the behavior of the vortex core size in both BCS and BEC regimes, we find that the vortex core size behaves quite differently for positive and negative chemical potentials. Project supported by the National Natural Science Foundation of China (Grant Nos. 51331006, 51590883, and 11204321) and the Project of Chinese Academy of Sciences (Grant No. KJZD-EW-M05-3).

  10. Size-Dependent Biexciton Quantum Yields and Carrier Dynamics of Quasi-Two-Dimensional Core/Shell Nanoplatelets.

    Science.gov (United States)

    Ma, Xuedan; Diroll, Benjamin T; Cho, Wooje; Fedin, Igor; Schaller, Richard D; Talapin, Dmitri V; Gray, Stephen K; Wiederrecht, Gary P; Gosztola, David J

    2017-09-05

    Quasi-two-dimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zero-dimensional quantum dots. We study lateral size-dependent photon emission statistics and carrier dynamics of individual NPLs using second-order photon correlation (g((2))(τ)) spectroscopy and photoluminescence (PL) intensity-dependent lifetime analysis. Room-temperature radiative lifetimes of NPLs can be derived from maximum PL intensity periods in PL time traces. It first decreases with NPL lateral size and then stays constant, deviating from the electric dipole approximation. Analysis of the PL time traces further reveals that the single exciton quantum yield in NPLs decreases with NPL lateral size and increases with protecting shell thickness, indicating the importance of surface passivation on NPL emission quality. Second-order photon correlation (g((2))(τ)) studies of single NPLs show that the biexciton quantum yield is strongly dependent on the lateral size and single exciton quantum yield of the NPLs. In large NPLs with unity single exciton quantum yield, the corresponding biexciton quantum yield can reach unity. These findings reveal that by careful growth control and core-shell material engineering, NPLs can be of great potential for light amplification and integrated quantum photonic applications.

  11. Effects of anisotropy and magnetic fields on the specific heat of a quasi-two-dimensional Boltzmann gas in an elliptical parabolic quantum dot

    Institute of Scientific and Technical Information of China (English)

    Zhai Zhi-Yuan; Li Yu-Qi; Pan Xiao-Yin

    2012-01-01

    We investigate the effects due to anisotropy and magnetic field interaction for a quasi-two-dimensional Boltzmann gas in an elliptical parabolic quantum dot.The specific heat is studied with varying temperature,anisotropy,and magnetic field strength.The cases without and with the inclusion of the spin Zeeman interaction are considered.

  12. Nuclear-magnetic-resonance relaxation due to the translational diffusion of fluid confined to quasi-two-dimensional pores

    Science.gov (United States)

    Faux, D. A.; McDonald, P. J.; Howlett, N. C.

    2017-03-01

    Nuclear-magnetic-resonance (NMR) relaxation experimentation is an effective technique for nondestructively probing the dynamics of proton-bearing fluids in porous media. The frequency-dependent relaxation rate T1-1 can yield a wealth of information on the fluid dynamics within the pore provided data can be fit to a suitable spin diffusion model. A spin diffusion model yields the dipolar correlation function G (t ) describing the relative translational motion of pairs of 1H spins which then can be Fourier transformed to yield T1-1. G (t ) for spins confined to a quasi-two-dimensional (Q2D) pore of thickness h is determined using theoretical and Monte Carlo techniques. G (t ) shows a transition from three- to two-dimensional motion with the transition time proportional to h2. T1-1 is found to be independent of frequency over the range 0.01-100 MHz provided h ≳5 nm and increases with decreasing frequency and decreasing h for pores of thickness h <3 nm. T1-1 increases linearly with the bulk water diffusion correlation time τb allowing a simple and direct estimate of the bulk water diffusion coefficient from the high-frequency limit of T1-1 dispersion measurements in systems where the influence of paramagnetic impurities is negligible. Monte Carlo simulations of hydrated Q2D pores are executed for a range of surface-to-bulk desorption rates for a thin pore. G (t ) is found to decorrelate when spins move from the surface to the bulk, display three-dimensional properties at intermediate times, and finally show a bulk-mediated surface diffusion (Lévy) mechanism at longer times. The results may be used to interpret NMR relaxation rates in hydrated porous systems in which the paramagnetic impurity density is negligible.

  13. Laserlike Vibrational Instability in Rectifying Molecular Conductors

    DEFF Research Database (Denmark)

    Lu, Jing Tao; Hedegård, Per; Brandbyge, Mads

    2011-01-01

    We study the damping of molecular vibrations due to electron-hole pair excitations in donor-acceptor (D-A) type molecular rectifiers. At finite voltage additional nonequilibrium electron-hole pair excitations involving both electrodes become possible, and contribute to the stimulated emission and...

  14. Negative differential resistance in molecular conductors

    Science.gov (United States)

    Kozhushner, Mortko; Oleynik, Ivan

    2007-03-01

    Negative differential resistance σd=dI/dVassymetrical. This results in an initial increase of the resonant molecular current as a resonant level appears in the interval of energies [EF, EF-eV] and a subsequent decrease of the current as the asymmetry in localization at the right and left interfaces is amplified upon further increase of applied bias.

  15. Binary cooperative NiCo2O4 on the nickel foams with quasi-two-dimensional precursors: a bridge between 'supercapacitor' and 'battery' in electrochemical energy storage.

    Science.gov (United States)

    Peng, Tao; Qian, Zhongyu; Wang, Jun; Qu, Liangti; Wang, Peng

    2015-02-28

    Some inorganic quasi-two-dimensional nanomaterials such as cobalt-nickel hydroxides are kinetically facile for a capacitive charge storage process. However, high performance capacitive charge storage needs a balance of the ionic and electronic transporting, and to build up an integrated architecture on substrates step by step and utilize the interface better is still a key challenge. As the interfacial assembly has conflicted with our goals for high-performance capacitive charge storage process, we identify theoretically and experimentally binary cooperative nanoscale interfacial materials to solve the problem. Co-Ni-hydroxide precursors were prepared by hybrid quasi-two-dimensional nanosheets and hetero-oriented nanocrystallines walls. Followed by dip-dry and annealing, NiCo2O4 could adhere to the nickel foams robustly with a solution-based surface treatment. Moreover, an unusual phenomenon in the electrochemical test inspired us to establish a bridge between 'supercapacitor' and 'battery'. The bridged gap highlights a new design idea for high-performance energy storage.

  16. Linear stability of horizontal, laminar fully developed, quasi-two-dimensional liquid metal duct flow under a transverse magnetic field and heated from below

    Science.gov (United States)

    Vo, Tony; Pothérat, Alban; Sheard, Gregory J.

    2017-03-01

    This study considers the linear stability of Poiseuille-Rayleigh-Bénard flows subjected to a transverse magnetic field, to understand the instabilities that arise from the complex interaction between the effects of shear, thermal stratification, and magnetic damping. This fundamental study is motivated in part by the desire to enhance heat transfer in the blanket ducts of nuclear fusion reactors. In pure magnetohydrodynamic flows, the imposed transverse magnetic field causes the flow to become quasi-two-dimensional and exhibit disturbances that are localized to the horizontal walls. However, the vertical temperature stratification in Rayleigh-Bénard flows feature convection cells that occupy the interior region, and therefore the addition of this aspect provides an interesting point for investigation. The linearized governing equations are described by the quasi-two-dimensional model proposed by Sommeria and Moreau [J. Fluid Mech. 118, 507 (1982), 10.1017/S0022112082001177], which incorporates a Hartmann friction term, and the base flows are considered fully developed and one-dimensional. The neutral stability curves for critical Reynolds and Rayleigh numbers, Rec and Rac, respectively, as functions of Hartmann friction parameter H have been obtained over 10-2≤H ≤104 . Asymptotic trends are observed as H →∞ following Rec∝H1 /2 and Rac∝H . The linear stability analysis reveals multiple instabilities which alter the flow both within the Shercliff boundary layers and the interior flow, with structures consistent with features from plane Poiseuille and Rayleigh-Bénard flows.

  17. Electronic band structure and Fermi surfaces of the quasi-two-dimensional monophosphate tungsten bronze, P4W12O44

    Science.gov (United States)

    Paul, S.; Ghosh, A.; Sato, T.; Sarma, D. D.; Takahashi, T.; Wang, E.; Greenblatt, M.; Raj, S.

    2014-02-01

    The electronic structure of quasi-two-dimensional monophosphate tungsten bronze, P4W12O44, has been investigated by high-resolution angle-resolved photoemission spectroscopy and density functional theoretical calculations. Experimental electron-like bands around \\Gamma point and Fermi surfaces have similar shapes as predicted by calculations. Fermi surface mapping at different temperatures shows a depletion of density of states at low temperature in certain flat portions of the Fermi surfaces. These flat portions of the Fermi surfaces satisfy the partial nesting condition with incommensurate nesting vectors q_1 and q_2 , which leads to the formation of charge density waves in this phosphate tungsten bronzes. The setting up of charge density wave in these bronzes can well explain the anomaly observed in its transport properties.

  18. O2- -to-F- substitution on the quasi-two-dimensional quantum antiferromagnet (CuCl)LaNb2O7

    Science.gov (United States)

    Tassel, C.; Kobayashi, Y.; Mitsuoka, S.; Takeiri, F.; Ajiro, Y.; Kageyama, H.

    2011-09-01

    We present the preparation of the electron-doped quasi-two dimensional quantum antiferromagnet (CuCl)LaNb2O7 by two step-wise topochemical reactions. The first step involves a reductive fluorination of the insulating layered perovskite RbLaNb2O7 using polytetrafluoroethylene that allows electric conduction in the perovskite blocks. The product RbLaNb2O6F was then ion-exchanged with copper dichloride to yield (CuCl)LaNb2O6F. The synchrotron x-ray diffraction study indicates that the structure of the final compound is different from that of the pure (CuCl)LaNb2O7.

  19. Quasi-two-dimensional quantum states of H{sub 2} in stage-2 Rb-intercalated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Smith, A.P.; Benedek, R.; Trouw, F.R.; Minkoff, M. [Argonne National Lab., IL (United States); Yang, L.H. [Lawrence Livermore National Lab., CA (United States). Physics/H-Div.

    1995-10-30

    Inelastic-incoherent-neutron scattering can be a valuable nanostructural probe of H{sub 2}-doped porous materials, provided the spectral peaks can be interpreted in terms of crystal-field-split hydrogen-molecule energy levels, which represent a signature of the local symmetry. Inelastic-neutron-scattering measurements as well as extensive theoretical analyses have been performed on stage-2 Rb-intercalated graphite (Rb-GIC), with physisorbed H{sub 2}, HD, and D{sub 2}, a layered porous system with abundant spectral peaks, to assess whether the crystal-field-state picture enables a quantitative understanding of the observed structure. Potential-energy surfaces for molecular rotational and translational motion, as well as the intermolecular interactions of hydrogen molecules in Rb-GIC, were calculated within local-density-functional theory (LDFT). Model potentials, parameterized using results of the LDFT calculations, were employed in schematic calculations of rotational and translational excited state spectra of a single physisorbed H{sub 2} molecule in Rb-GIC. Results of the analysis are basically consistent with the assignment by Stead et al. of the lowest-lying peak at 1.4 meV to a rotational-tunneling transition of an isotropic hindered-rotor oriented normal to the planes, but indicate a small azimuthal anisotropy and a lower barrier than for the isotropic case. Based on the experimental isotope shifts and the theoretically predicted states, they conclude that spectral peaks at 11 and 22 meV are most likely related to center of mass excitations.

  20. Interplay between Ferroelastic and Metal-Insulator Phase Transitions in Strained Quasi-Two-Dimensional VO2 Nanoplatelets

    Energy Technology Data Exchange (ETDEWEB)

    Tselev, Alexander [ORNL; Strelcov, Evgheni [Southern Illinois University; Luk' yanchuk, Prof. Igor A. [University of Picardie Jules Verne, Amiens, France; Ivanov, Ilia N [ORNL; Budai, John D [ORNL; Tischler, Jonathan Zachary [ORNL; Jones, Keith M [ORNL; Proksch, Roger [Asylum Research, Santa Barbara, CA; Kalinin, Sergei V [ORNL; Kolmakov, Andrei [ORNL

    2010-01-01

    Formation of ferroelastic twin domains in VO_2 nanosystems can strongly affect local strain distributions, and hence couple to the strain-controlled metal-insulator transition. Here we report polarized-light optical and scanning microwave microscopy studies of interrelated ferroelastic and metal-insulator transitions in single-crystalline vanadium dioxide (VO_2) quasi-two-dimensional (quasi-2D) nanoplatelets (NPls). In contrast to quasi-1D single-crystalline nanobeams, the geometric frustration results in emergence of several possible families of ferroelastic domains in NPls, thus allowing systematic studies of strain-controlled transitions in the presence of geometrical frustration. We demonstrate possibility of controlling the ferroelastic domain population by the strength of the NPl-substrate interaction, mechanical stress, and by the NPl lateral size. Ferroelastic domain species and domain walls are identified based on standard group-theoretical considerations. Using variable temperature microscopy, we imaged the development of domains of metallic and semiconducting phases during the metal-insulator phase transition and non-trivial strain-driven reentrant domain formation. A long-range reconstruction of ferroelastic structures accommodating metal-insulator domain formation has been observed. These studies illustrate that complete picture of the phase transitions in single-crystalline and disordered VO_2 structures can be drawn only if both ferroelastic and metal-insulator strain effects are taken into consideration and understood.

  1. Quasi-two-dimensional subthreshold current model of deep submicrometer SOI drive-in gate controlled hybrid transistors with lateral non-uniform doping profile

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We have analyzed the operating mechanism of the novel deep submicrometer SOI drive-in gate controlled hybrid transistor (DGCHT), which can effectively alleviate the contradiction between speed enhancement and power reduction in conventional MOS devices and can improve the output resistance. On the basis of this, the subthreshold current model of DGCHTs is proposed. The model takes into account the impact of lateral non-uniform doping profile on body effect, short-channel effect and carrier mobility. Considering the mobile charge, two-dimensional Poisson equation is solved with quasi-two-dimensional analysis and parabolic approximation of surface potential. With the surface potential obtained, the subthreshold current is figured out, including both the diffusion and drift component. The calculated results are in good agreement with the MEDICI numerical simulation results, indicating the correct description of the current characteristics of SOI DGCHT by the presented model. The model can also be considered as an important reference to the current simulation of deep submicrometer MOSFET with pocket implantation.

  2. H-T phase diagram and the nature of vortex-glass phase in a quasi-two-dimensional superconductor: Sn-metal layer sandwiched between graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Masatsugu; Suzuki, Itsuko S.; Walter, Juergen

    2004-02-15

    The magnetic properties of a quasi-two-dimensional (2D) superconductor, Sn-metal graphite (MG), are studied using DC and AC magnetic susceptibility. Sn-MG has a unique layered structure where Sn metal layer is sandwiched between adjacent graphene sheets. This compound undergoes a superconducting transition at T{sub c}=3.75 K at H=0. The H-T diagram of Sn-MG is similar to that of a quasi-2D superconductors. The phase boundaries of vortex liquid, vortex glass, and vortex lattice phase merge into a multicritical point located at T*=3.4 K and H*=40 Oe. There are two irreversibility lines denoted by H{sub gl} (de Almeida-Thouless type) and H{sub gl{sup '}} (Gabay-Toulouse type), intersecting at T{sub 0}{sup '}=2.5 K and H{sub 0}{sup '}=160 Oe. The nature of slow dynamic and nonlinearity of the vortex glass phase is studied.

  3. Quasi-two-dimensional Bose-Einstein condensation of spin triplets in the dimerized quantum magnet Ba2CuSi2O6Cl2

    Science.gov (United States)

    Okada, Makiko; Tanaka, Hidekazu; Kurita, Nobuyuki; Johmoto, Kohei; Uekusa, Hidehiro; Miyake, Atsushi; Tokunaga, Masashi; Nishimoto, Satoshi; Nakamura, Masaaki; Jaime, Marcelo; Radtke, Guillaume; Saúl, Andrés

    2016-09-01

    We synthesized single crystals of composition Ba2CuSi2O6Cl2 and investigated their quantum magnetic properties. The crystal structure is closely related to that of the quasi-two-dimensional (2D) dimerized magnet BaCuSi2O6 also known as Han purple. Ba2CuSi2O6Cl2 has a singlet ground state with an excitation gap of Δ /kB=20.8 K. The magnetization curves for two different field directions almost perfectly coincide when normalized by the g factor except for a small jump anomaly for a magnetic field perpendicular to the c axis. The magnetization curve with a nonlinear slope above the critical field is in excellent agreement with exact-diagonalization calculations based on a 2D coupled spin-dimer model. Individual exchange constants are also evaluated using density functional theory (DFT). The DFT results demonstrate a 2D exchange network and weak frustration between interdimer exchange interactions, supported by weak spin-lattice coupling implied from our magnetostriction data. The magnetic-field-induced spin ordering in Ba2CuSi2O6Cl2 is described as the quasi-2D Bose-Einstein condensation of triplets.

  4. Anisotropic electronic and magnetic properties of the quasi-two-dimensional heavy-fermion antiferromagnet CeRhIn{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Cornelius, A. L.; Arko, A. J.; Sarrao, J. L.; Hundley, M. F.; Fisk, Z.

    2000-12-01

    We have used high pulsed magnetic fields to 50 T to observe de Haas--van Alphen oscillations in the tetragonal antiferromagnet CeRhIn{sub 5}, which has an enhanced value of the electronic specific heat coefficient {gamma}{approx}>420 mJ/molK{sup 2}. For Tquasi-two-dimensional crystal structure.

  5. Synthesis and Structure of A Novel Quasi-Two Dimensional Organic-inorganic Hybrid Coordination Polymer:{[Cu(en)2][Ag2I4]}n

    Institute of Scientific and Technical Information of China (English)

    SUN Ling-Guo; LI Hao-Hong; CHEN Zhi-Rong; HUANG Chang-Cang; ZHAO Bin; LI Jun-Qian

    2006-01-01

    A novel coordination polymer {[Cu(en)2][Ag2I4]}n (en = ethylenediamine) was synthesized by the reaction of NaAgI2 and Cu(en)2(NO3)2·2H2O at room temperature with pH = 6.0, and the structure was characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group C2/m, with a=10.646(2), b = 13.304(3), c = 6.8445(14)(A), β = 118.95(3)°, C4H16N4CuAg2I4, Mr = 907.10, V = 848.3(4)(A)3, Z = 2, Dc = 3.551 g/cm3, F(000) = 806, μ(MoKα) = 10.787 mm(1, the final R1 = 0.0256 and wR2 = 0.0654 for 900 observed reflections with I > 2σ(I). According to structural analysis, the title compound consists of template cation [Cu(en)2]2+ and inorganic chain [Ag2I4]n2-. The polymeric negative chain [Ag2I4]n2- is built up from pairs of AgI4 tetrahedron by sharing one edge. Through N-H…I hydrogen-bonding interactions, the whole structure represents a quasi-two dimensional arrangement. Electrostatic attraction exists between organic cations and inorganic chains, leading to a so-called organic-inorganic hybrid structure.

  6. Optical investigation of the quasi-two-dimensional Mott system Ca_2-xSr_xRuO4 (0.0<= x<= 2.0)

    Science.gov (United States)

    Lee, J. S.; Noh, T. W.; Lee, Y. S.; Oh, S.-J.; Nakatsuji, S.; Maeno, Y.

    2002-03-01

    The doping and temperature dependent optical conductivity spectra σ (ω ) in the ab-plane of the quasi-two-dimensional system Ca_2-xSr_xRuO4 (0.0= 0.2, the σ (ω ) show features of the Mott-Hubbard system. However, the insulating spectra of x=0.00 and 0.06 show an unusual two-peak structure around 1.0 and 2.0 eV. From the systematic changes with doping, it was found that both excitations have the correlation-induced Ru 4 d characters. Interestingly, for the x=0.06 sample, softening of the streching phonon mode and strong spectral weight redistribution between these two peaks were observed with decreasing temperature. These could be understood by the orbital occupancy changes with the RuO6 octahedral flattening. Possible connections to the critical behaviors of the specific heat and susceptibility at x=0.5 will be also discussed.

  7. Quasi-two-dimensional superconductivity in FeSe0.3Te0.7 thin films and electric-field modulation of superconducting transition.

    Science.gov (United States)

    Lin, Zhu; Mei, Chenguang; Wei, Linlin; Sun, Zhangao; Wu, Shilong; Huang, Haoliang; Zhang, Shu; Liu, Chang; Feng, Yang; Tian, Huanfang; Yang, Huaixin; Li, Jianqi; Wang, Yayu; Zhang, Guangming; Lu, Yalin; Zhao, Yonggang

    2015-09-18

    We report the structural and superconducting properties of FeSe0.3Te0.7 (FST) thin films with different thicknesses grown on ferroelectric Pb(Mg1/3Nb2/3)0.7Ti0.3O3 substrates. It was shown that the FST films undergo biaxial tensile strains which are fully relaxed for films with thicknesses above 200 nm. Electrical transport measurements reveal that the ultrathin films exhibit an insulating behavior and superconductivity appears for thicker films with Tc saturated above 200 nm. The current-voltage curves around the superconducting transition follow the Berezinskii-Kosterlitz-Thouless (BKT) transition behavior and the resistance-temperature curves can be described by the Halperin-Nelson relation, revealing quasi-two-dimensional phase fluctuation in FST thin films. The Ginzburg number decreases with increasing film thickness indicating the decrease of the strength of thermal fluctuations. Upon applying electric field to the heterostructure, Tc of FST thin film increases due to the reduction of the tensile strain in FST. This work sheds light on the superconductivity, strain effect as well as electric-field modulation of superconductivity in FST films.

  8. Free Molecular Heat Transfer Programs for Setup and Dynamic Updating the Conductors in Thermal Desktop

    Science.gov (United States)

    Malroy, Eric T.

    2007-01-01

    The programs, arrays and logic structure were developed to enable the dynamic update of conductors in thermal desktop. The MatLab program FMHTPRE.m processes the Thermal Desktop conductors and sets up the arrays. The user needs to manually copy portions of the output to different input regions in Thermal Desktop. Also, Fortran subroutines are provided that perform the actual updates to the conductors. The subroutines are setup for helium gas, but the equations can be modified for other gases. The maximum number of free molecular conductors allowed is 10,000 for a given radiation task. Additional radiation tasks for FMHT can be generated to account for more conductors. Modifications to the Fortran subroutines may be warranted, when the mode of heat transfer is in the mixed or continuum mode. The FMHT Thermal Desktop model should be activated by using the "Case Set Manager" once the model is setup. Careful setup of the model is needed to avoid excessive solve times.

  9. Quasi-two-dimensional Fermi surfaces in the flat antiferromagnetic Brillouin zone of NpRhGa{sub 5} studied by dHvA experiments and energy band calculations

    Energy Technology Data Exchange (ETDEWEB)

    Aoki, Dai [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Yamagami, Hiroshi [Department of Physics, Faculty of Science, Kyoto Sangyo University, Kyoto 603-8555 (Japan); Homma, Yoshiya [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Shiokawa, Yoshinobu [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Yamamoto, Etsuji [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Nakamura, Akio [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Haga, Yoshinori [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Settai, Rikio [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan); Onuki, Yoshichika [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan)

    2005-05-04

    We succeeded in growing a high-quality single crystal of NpRhGa{sub 5} by the Ga-flux method and observed the de Haas-van Alphen oscillation in the antiferromagnetic state. Four kinds of nearly cylindrical Fermi surfaces, which correspond to main Fermi surfaces, were clearly detected. These quasi-two-dimensional Fermi surfaces are formed in the flat antiferromagnetic Brillouin zone and are well explained on the basis of spin- and orbital-polarized LAPW energy band calculations. The cyclotron masses are moderately enhanced, ranging from 8.1 to 11.7 m{sub 0}, which are approximately four times larger than the corresponding band masses. This is the first case where the 5f-itinerant band model is applicable to a neptunium magnetic compound. (letter to the editor)

  10. Evidence for the quasi-two dimensional behavior of the vortex structure in Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8] single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Pastoriza, H. (Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina)); Arribere, A. (Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina)); Goffman, M.F. (Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina)); Cruz, F. de la (Comision Nacional de Energia Atomica, Centro Atomico Bariloche (Argentina)); Mitzi, D.B. (Dept. of Applied Physics, Stanford Univ., CA (United States)); Kapitulnik, A. (Dept. of Applied Physics, Stanford Univ., CA (United States))

    1994-02-01

    AC susceptibility and dc magnetization measurements on Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8] (BSCCO) single crystals in a wide range of temperatures clearly show that below the dc irreversibility line the vortex system loss the long range order in the c direction. The susceptibility data taken at 7 Hz show the different nature of two dissipation peaks: One related to the interplane currents at temperatures well below the dc irreversibility line and the other associated with the intraplane ones at temperatures above that line. In this sense the irreversibility line corresponds to the temperature where quasi-two dimensional vortices are depinned. (orig.)

  11. Quasi-two-dimensional electron gas at the epitaxial alumina/SrTiO{sub 3} interface: Control of oxygen vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Kormondy, Kristy J.; Posadas, Agham B.; Demkov, Alexander A., E-mail: demkov@physics.utexas.edu [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Ngo, Thong Q.; Ekerdt, John G. [Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States); Lu, Sirong; Smith, David J.; McCartney, Martha R. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States); Goble, Nicholas; Gao, Xuan P. A. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Jordan-Sweet, Jean [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

    2015-03-07

    In this paper, we report on the highly conductive layer formed at the crystalline γ-alumina/SrTiO{sub 3} interface, which is attributed to oxygen vacancies. We describe the structure of thin γ-alumina layers deposited by molecular beam epitaxy on SrTiO{sub 3} (001) at growth temperatures in the range of 400–800 °C, as determined by reflection-high-energy electron diffraction, x-ray diffraction, and high-resolution electron microscopy. In situ x-ray photoelectron spectroscopy was used to confirm the presence of the oxygen-deficient layer. Electrical characterization indicates sheet carrier densities of ∼10{sup 13 }cm{sup −2} at room temperature for the sample deposited at 700 °C, with a maximum electron Hall mobility of 3100 cm{sup 2}V{sup −1}s{sup −1} at 3.2 K and room temperature mobility of 22 cm{sup 2}V{sup −1}s{sup −1}. Annealing in oxygen is found to reduce the carrier density and turn a conductive sample into an insulator.

  12. Effects of electron-phonon interaction on thermal and electrical transport through molecular nano-conductors

    Energy Technology Data Exchange (ETDEWEB)

    Lü, Jing-Tao, E-mail: jtlu@hust.edu.cn [School of Physics, Huazhong University of Science and Technology, 430074 Wuhan (China); Zhou, Hangbo [Department of Physics and Center for Computational Science and Engineering, National University of Singapore, 117551 Singapore (Singapore); NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, 117456 Singapore (Singapore); Jiang, Jin-Wu [Shanghai Institute of Applied Mathematics and Mechanics, Shanghai Key Laboratory of Mechanics in Energy Engineering, Shanghai University, 200072 Shanghai (China); Wang, Jian-Sheng [Department of Physics and Center for Computational Science and Engineering, National University of Singapore, 117551 Singapore (Singapore)

    2015-05-15

    The topic of this review is the effects of electron-phonon interaction (EPI) on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green’s function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system’s thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor’s atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons.

  13. Effects of electron-phonon interaction on thermal and electrical transport through molecular nano-conductors

    Directory of Open Access Journals (Sweden)

    Jing-Tao Lü

    2015-05-01

    Full Text Available The topic of this review is the effects of electron-phonon interaction (EPI on the transport properties of molecular nano-conductors. A nano-conductor connects to two electron leads and two phonon leads, possibly at different temperatures or chemical potentials. The EPI appears only in the nano-conductor. We focus on its effects on charge and energy transport. We introduce three approaches. For weak EPI, we use the nonequilibrium Green’s function method to treat it perturbatively. We derive the expressions for the charge and heat currents. For weak system-lead couplings, we use the quantum master equation approach. In both cases, we use a simple single level model to study the effects of EPI on the system’s thermoelectric transport properties. It is also interesting to look at the effect of currents on the dynamics of the phonon system. For this, we derive a semi-classical generalized Langevin equation to describe the nano-conductor’s atomic dynamics, taking the nonequilibrium electron system, as well as the rest of the atomic degrees of freedom as effective baths. We show simple applications of this approach to the problem of energy transfer between electrons and phonons.

  14. Chemical synthesis and assembly of quasi-two-dimensional metal chalcogenides graphene analogues%准二维金属硫属化合物类石墨烯结构的化学合成与组装

    Institute of Scientific and Technical Information of China (English)

    冯冯; 冯骏; 吴长征; 谢毅

    2012-01-01

    Inorganic graphene analogues are regarded as a typical quasi-two-dimensional nanostructure system. Graphene analogues entail more structural parameters that could be controlled compared with the pure-carbon graphene, which leads to the well controlled energy-band type and gap width, showing the promising signs in constructing electronic device in the field of energy conversion and energy storage. In this regard, metal chalcogenides (MCs) have drawn extensive attention as an important graphene analogue material system due to its unique quasi-two dimensional crystallographic structure. Herein, we reviewed the synthesis and assembly methodologies for graphene analogues of MCs, as well as their functional applications of their assembled nanostructures. We put forward the strategies that utilizing chemical methods to weaken interlayer force and embodying the highly anisotropic characteristics in the internal structural lattices to successfully realize the fabrication of graphene analogues. Finally, we also summarized the assembly strategy of graphene analogues and their promising applications in the area of energy storage and intelligent responsiveness nanodevices.%无机类石墨烯属于准二维纳米结构体系,因其具有比纯碳石墨烯本身更多的调控参数,比如带隙类型及其带隙宽度可调节等,在电子器件构筑和能量转化存储等领域有着重要的科学意义和广阔的应用前景.近年来,具有准二维特征的金属硫属化合物(metal chalcogenides,MCs)作为类石墨烯结构的重要材料体系受到了广泛关注.本文概述了近年来金属硫属化合物类石墨烯结构的化学制备方法及其可能的组装应用,提出了通过系列方法影响层间作用力及利用晶体各向异性等材料设计与合成策略来实现类石墨烯的化学合成,并展望了类石墨烯的组装结构在能量存储与智能传感领域的应用前景.

  15. ab initio Studies on Molecular Conductor (BEDSe-TTF)2[Fe(CN)5NO

    Institute of Scientific and Technical Information of China (English)

    YAO Kai-Lun; TU Hai-Bo; WANG Wei-Zhong

    2001-01-01

    In this paper the ab initio study using pseudopotential plane wave method with the local spin density functional approximation is presented for the molecular conductor (BEDSe-TTF)2[Fe(CN)5NO]. The mean electronic density distributions are obtained, and we find that the extended π orbital of the selenium does not affect the properties of material as assumed in other papers and the "side-by-side" type S...S interaction is the primary interaction between donors. From band structure calculations we analyze the influence of the NO groups on the electronic structure and magnetic properties of molecule. It is shown that the itinerant electrons important to electronic properties in these types of hybrids are delocalized electrons contributed by NO groups, instead of by the 3d electrons of Fe. Additionally, we have found that the localized magnetic moment is also contributed by the NO groups in this molecular conductor. From total energy calculations the molecular structure with the lowest energy is found due to the interaction between split spins, and the particular positions of the NO groups are obtained.

  16. Topological phase transition of decoupling quasi-two-dimensional vortex pairs in La1- y Sm y MnO3 + δ ( y = 0.85, 1.0)

    Science.gov (United States)

    Bukhanko, F. N.; Bukhanko, A. F.

    2016-10-01

    Characteristic signs of the universal Nelson-Kosterlitz jump of the superconducting liquid density in the temperature dependences of the magnetization of La1- y Sm y MnO3 + δ samples with samarium concentrations y = 0.85 and 1.0, which are measured in magnetic fields 100 Oe ≤ H ≤ 3.5 kOe, are detected. As the temperature increases, the sample with y = 0.85 exhibits a crescent-shaped singularity in the dc magnetization curve near the critical temperature of decoupling vortex-antivortex pairs ( T KT ≡ T c ≈ 43 K), which is independent of measuring magnetic field H and is characteristic of the dissociation of 2D vortex pairs. A similar singularity is also detected in the sample with a samarium concentration y = 1.0 at a significantly lower temperature ( T KT ≈ 12 K). The obtained experimental results are explained in terms of the topological Kosterlitz-Thouless phase transition of dissociation of 2D vortex pairs in a quasi-two-dimensional weak Josephson coupling network.

  17. Fingerprints of field-induced Berezinskii-Kosterlitz-Thouless transition in quasi-two-dimensional S=1/2 Heisenberg magnets Cu(en)(H2O)2SO4 and Cu(tn)Cl2

    Science.gov (United States)

    Baranová, Lucia; Orendáčová, Alžbeta; Čižmár, Erik; Tarasenko, Róbert; Tkáč, Vladimír; Orendáč, Martin; Feher, Alexander

    2016-04-01

    Organo-metallic compounds Cu(en)(H2O)2SO4 (en=C2H8N2) and Cu(tn)Cl2 (tn=C3H10N2) representing S=1/2 quasi-two-dimensional Heisenberg antiferromagnets with an effective intra-layer exchange coupling J/kB≈3 K, have been examined by specific heat measurements at temperatures down to nominally 50 mK and magnetic fields up to 14 T. A comparative analysis of magnetic specific heat in zero magnetic field revealed nearly identical contribution of short-range magnetic correlations and significant differences were observed at lowest temperatures. A phase transition to long-range order was observed in Cu(en)(H2O)2SO4 at TC=0.9 K while hidden in Cu(tn)Cl2. A response of both compounds to the application of magnetic field has rather universal features characteristic for a field-induced Berezinskii-Kosterlitz-Thouless transition theoretically predicted for ideal two-dimensional magnets.

  18. Commensurate and incommensurate states of a spin density wave in a quasi-two-dimensional system with an anisotropic energy spectrum in an external magnetic field of arbitrary direction relative to magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Palistrant, M. E., E-mail: mepalistrant@yandex.com; Ursu, V. A. [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of)

    2013-04-15

    A theory of thermodynamic properties of a spin density wave (SDW) in a quasi-two-dimensional system (with a preset impurity concentration x) is constructed. We choose an anisotropic dispersion relation for the electron energy and assume that external magnetic field H has an arbitrary direction relative to magnetic moment M{sub Q}. The system of equations defining order parameters M{sub Q}{sup z}, M{sub Q}{sup {sigma}}, M{sub z}, and M{sup {sigma}} is constructed and transformed with allowance for the Umklapp processes. Special cases when H Double-Vertical-Line M{sub Q} and H Up-Tack M{sub Q} (H{sub Z}H{sup {sigma}} = 0) are considered in detail as well as cases of weak fields H of arbitrary direction. The condition for the transition of the system to the commensurate and incommensurate states of the SDW is analyzed. The concentration dependence of magnetic transition temperature T{sub M} is calculated, and the components of the order parameter for the incommensurate phase are determined. The phase diagram (T,{approx}x) is constructed. The effect of the magnetic field on magnetic transition temperature T{sub M} is analyzed for H{sub Z}H{sup {sigma}} = 0, and longitudinal magnetic susceptibility {chi} Double-Vertical-Line is calculated; this quantity demonstrates the temperature dependence corresponding to a system with a gap for x < x{sub c} and to a gapless state for x > x{sub c}. In the immediate vicinity of the critical impurity concentration (x {approx} x{sub c}), the temperature dependence of the magnetic susceptibility acquires a local maximum. The effect of anisotropy of the electron energy spectrum on the investigated physical quantities is also analyzed.

  19. Quasi-two-dimensional electron gas at the interface of γ-Al{sub 2}O{sub 3}/SrTiO{sub 3} heterostructures grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ngo, Thong Q.; McDaniel, Martin D.; Ekerdt, John G., E-mail: ekerdt@che.utexas.edu [Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States); Goble, Nicholas J.; Gao, Xuan P. A. [Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Posadas, Agham; Kormondy, Kristy J.; Demkov, Alexander A. [Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States); Lu, Sirong [School of Engineering for Matter, Transport and Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Jordan-Sweet, Jean [IBM T.J. Watson Research Center, Yorktown Heights, New York 10598 (United States); Smith, David J. [Department of Physics, Arizona State University, Tempe, Arizona 85287 (United States)

    2015-09-21

    We report the formation of a quasi-two-dimensional electron gas (2-DEG) at the interface of γ-Al{sub 2}O{sub 3}/TiO{sub 2}-terminated SrTiO{sub 3} (STO) grown by atomic layer deposition (ALD). The ALD growth of Al{sub 2}O{sub 3} on STO(001) single crystal substrates was performed at temperatures in the range of 200–345 °C. Trimethylaluminum and water were used as co-reactants. In situ reflection high energy electron diffraction, ex situ x-ray diffraction, and ex situ cross-sectional transmission electron microscopy were used to determine the crystallinity of the Al{sub 2}O{sub 3} films. As-deposited Al{sub 2}O{sub 3} films grown above 300 °C were crystalline with the γ-Al{sub 2}O{sub 3} phase. In situ x-ray photoelectron spectroscopy was used to characterize the Al{sub 2}O{sub 3}/STO interface, indicating that a Ti{sup 3+} feature in the Ti 2p spectrum of STO was formed after 2–3 ALD cycles of Al{sub 2}O{sub 3} at 345 °C and even after the exposure to trimethylaluminum alone at 300 and 345 °C. The interface quasi-2-DEG is metallic and exhibits mobility values of ∼4 and 3000 cm{sup 2} V{sup −1} s{sup −1} at room temperature and 15 K, respectively. The interfacial conductivity depended on the thickness of the Al{sub 2}O{sub 3} layer. The Ti{sup 3+} signal originated from the near-interfacial region and vanished after annealing in an oxygen environment.

  20. Conformational Solvation Studies of LIGNOLs with Molecular Dynamics and Conductor-Like Screening Model

    Directory of Open Access Journals (Sweden)

    Thomas Sandberg

    2012-08-01

    Full Text Available Molecular dynamics (MD simulations were performed on sterically hindered -conidendrin-based chiral 1,4-diols (LIGNOLs from the naturally occurring lignan hydroxymatairesinol (HMR using the GROMACS software. The aim of this study was to explore the conformational behaviour of the LIGNOLs in aqueous solution adopting the TIP4P model. The topologies of the LIGNOLs were constructed manually and they were modeled with the OPLS-AA force field implemented in GROMACS. The four most relevant torsional angles in the LIGNOLs were properly analyzed during the simulations. The determining property for the conformation preferred in aqueous solution was found to be the lowest energy in gas phase. The solvation effects on the LIGNOLs were also studied by quantum chemical calculations applying the COnductor-like Screening MOdel (COSMO. The hydration studies of the MD simulations showed that several of these LIGNOLs, produced from a renewable source, have a great potential of acting as chiral catalysts.

  1. La modelización molecular como herramienta para el diseño de nuevos polímeros conductores

    OpenAIRE

    Casanovas, Jordi; Armelin,Elaine; Iribarren,José Ignacio; Alemán, Carlos; Liesa,Francisco

    2005-01-01

    Se presenta la capacidad de las técnicas de modelización molecular basadas en métodos de la química cuántica para predecir la estructura molecular y electrónica de polímeros conductores. Concretamente, se discute la aplicabilidad de estas herramientas computacionales al estudio de diferentes aspectos del politiofeno y sus derivados: geometría molecular y planaridad, cambios estructurales producidos por el dopado, propiedades electrónicas y desarrollo de nuevos materiales conductores.

  2. Multidimensional Nature of Molecular Organic Conductors Revealed by Angular Magnetoresistance Oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Pashupati Dhakal, Harukazu Yoshino, Jeong-Il Oh, Koichi Kikuchi, Michael J. Naughton

    2012-09-01

    Angle-dependent magnetoresistance experiments on organic conductors exhibit a wide range of angular oscillations associated with the dimensionality and symmetry of the crystal structure and electron energy dispersion. In particular, characteristics associated with 1, 2, and 3-dimensional electronic motion are separately revealed when a sample is rotated through different crystal planes in a magnetic field. Originally discovered in the TMTSF-based conductors, these effects are particularly pronounced in the related system (DMET){sub 2}I{sub 3}. Here, experimental and computational results for magnetoresistance oscillations in this material, over a wide range of magnetic field orientations, are presented in such a manner as to uniquely highlight this multidimensional behavior. The calculations employ the Boltzmann transport equation that incorporates the system's triclinic crystal structure, which allows for accurate estimates of the transfer integrals along the crystallographic axes, verifying the 1D, 2D and 3D nature of (DMET){sub 2}I{sub 3}, as well as crossovers between dimensions in the electronic behavior.

  3. Blowing the fuse: Berry's phase and runaway vibrations in molecular conductors.

    Science.gov (United States)

    Lü, Jing-Tao; Brandbyge, Mads; Hedegård, Per

    2010-05-12

    We examine a molecular bridge connecting two metallic electrodes. We find that an electronic current passing across the bridge can cause a vibrational instability of the molecule, which ultimately can lead to a breakdown of the bridge. This instability is generated by a hitherto never considered mechanism, which surprisingly involves the quantum mechanical phase of the electronic waves, the "Berry phase". This mechanism works for highly conducting bridges, and contrary to breakdown by traditional Joule heating, this instability is deterministic and occurs at certain critical voltages. We demonstrate the new mechanism using state-of-the-art ab initio calculations on realistic molecular bridges.

  4. Synthesis of Ruthenium(III Phthalocyanine with Di-axial Bromo Ligands - A Promising Molecular Conductor with Giant Negative Magnetoresistance

    Directory of Open Access Journals (Sweden)

    Mario A.V. Gamboa

    2015-01-01

    Full Text Available The electron transport of Phthalocyanines (Pc with central metal and di-axial ligands (such as FeIII(PcL2; where L = CN, Cl, Br originates from its intermolecular Pc π-π orbital overlap while its giant negative magnetoresistance (GNMR arises from its intramolecular Pc-π(HOMO and Fe-d (s=1/2 interaction. However, the π-d interaction tends to localize itinerant electrons resulting in the decrease in the conductivity of the FeIII(PcL2 series compared to the non-magnetic CoIII(PcL2 where π-d interaction is absent. More so, the axial ligand field energy of the FeIII(PcL2 system is found to have the ability to proportionally modulate the π-d interaction. In reference thereof, theoretical calculations point that isostructural RuIII(PcBr2 would provide the best balance of π-d orbital energy interplay. That is, RuIII(PcBr2 is expected to be a molecule with high electrical conductivity and GNMR which would make it an ideal magnetic molecular conductor. This paper reports on the synthesis of RuIII(PcBr2.

  5. Anomalous metallic state of the one-dimensional molecular conductor (EDO-TTFBr2)3I3

    Science.gov (United States)

    Miyazaki, A.; Kato, T.; Yamazaki, H.; Enoki, T.; Ogura, E.; Kuwatani, Y.; Iyoda, M.; Yamaura, J.

    2003-08-01

    The structure and physical properties of the one-dimensional (1D) molecular conductor (EDO-TTFBr2)3I3 are reported. This salt is composed of quasi-1D uniform stacks of the donor molecules and counter anions which are translationally disordered at room temperature. The temperature dependence of the lattice constants shows that, as the temperature decreases, the thermal contraction takes place along the donor columns, leading to the enhancement of the one-dimensionality of the π-electron system. The electrical conductivity and thermoelectric power show a metallic conductivity down to circa 140 K, where a metal-insulator transition takes place. The transition temperature decreases to circa 60 K as the hydrostatic pressure is applied up to 1.1 GPa. Although the transport properties give the itinerant feature of the π electrons, the static susceptibility behaves as a 1D Heisenberg antiferromagnetlike behavior of localized spins from room temperature down to 15 K, which is consistent with the ESR linewidth governed by the 1D diffusion mechanism of localized spins. The coexistence of the itinerant character of the transport properties and the localized character of the magnetic properties of the π-electron system is attributed to the strongly correlated nature of the quasi-1D electron system.

  6. La modelización molecular como herramienta para el diseño de nuevos polímeros conductores Molecular modeling tools to design new conducting polymers

    Directory of Open Access Journals (Sweden)

    Jordi Casanovas

    2005-11-01

    Full Text Available Se presenta la capacidad de las técnicas de modelización molecular basadas en métodos de la química cuántica para predecir la estructura molecular y electrónica de polímeros conductores. Concretamente, se discute la aplicabilidad de estas herramientas computacionales al estudio de diferentes aspectos del politiofeno y sus derivados: geometría molecular y planaridad, cambios estructurales producidos por el dopado, propiedades electrónicas y desarrollo de nuevos materiales conductores.The ability of molecular modeling techniques based on quantum chemical methods to predict the molecular and electronic structure of organic conducting polymers is examined. More specifically, we report on the applicability of these computational tools to study different aspects of polythiophene and its derivatives: molecular geometry and planarity, the structural changes induced by the doping process, the electronic properties and the design of new conducting materials.

  7. Mechanically driven growth of quasi-two dimensional microbial colonies

    CERN Document Server

    Farrell, F D C; Marenduzzo, D; Waclaw, B

    2013-01-01

    We study colonies of non-motile, rod-shaped bacteria growing on solid substrates. In our model, bacteria interact purely mechanically, by pushing each other away as they grow, and consume a diffusing nutrient. We show that mechanical interactions control the velocity and shape of the advancing front, which leads to features that cannot be captured by established Fisher-Kolmogorov models. In particular, we find that the velocity depends on the elastic modulus of bacteria or their stickiness to the surface. Interestingly, we predict that the radius of an incompressible, strictly two-dimensional colony cannot grow linearly in time. Importantly, mechanical interactions can also account for the nonequilibrium transition between circular and branching colonies, often observed in the lab.

  8. Quasi two-dimensional astigmatic solitons in soft chiral metastructures

    Science.gov (United States)

    Laudyn, Urszula A.; Jung, Paweł S.; Karpierz, Mirosław A.; Assanto, Gaetano

    2016-03-01

    We investigate a non-homogeneous layered structure encompassing dual spatial dispersion: continuous diffraction in one transverse dimension and discrete diffraction in the orthogonal one. Such dual diffraction can be balanced out by one and the same nonlinear response, giving rise to light self-confinement into astigmatic spatial solitons: self-focusing can compensate for the spreading of a bell-shaped beam, leading to quasi-2D solitary wavepackets which result from 1D transverse self-localization combined with a discrete soliton. We demonstrate such intensity-dependent beam trapping in chiral soft matter, exhibiting one-dimensional discrete diffraction along the helical axis and one-dimensional continuous diffraction in the orthogonal plane. In nematic liquid crystals with suitable birefringence and chiral arrangement, the reorientational nonlinearity is shown to support bell-shaped solitary waves with simple astigmatism dependent on the medium birefringence as well as on the dual diffraction of the input wavepacket. The observations are in agreement with a nonlinear nonlocal model for the all-optical response.

  9. Blast shocks in quasi-two-dimensional supersonic granular flows.

    Science.gov (United States)

    Boudet, J F; Cassagne, J; Kellay, H

    2009-11-27

    In a thin, dilute, and fast flowing granular layer, the impact of a small sphere generates a fast growing hole devoid of matter. The growth of this hole is studied in detail, and its dynamics is found to mimic that of blast shocks in gases. This dynamics can be decomposed into two stages: a fast initial stage (the blast) and a slower growth regime whose growth velocity is given by the speed of sound in the medium used. A simple model using ingredients already invoked for the case of blast shocks in gases but including the inelastic nature of collisions between grains accounts accurately for our results. The system studied here allows for a detailed study of the full dynamics of a blast as it relaxes from a strong to a weak shock and later to an acoustic disturbance.

  10. Drift modes of a quasi-two-dimensional current sheet

    Energy Technology Data Exchange (ETDEWEB)

    Artemyev, A. V.; Malova, Kh. V.; Popov, V. Yu.; Zelenyi, L. M. [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    2012-03-15

    Stability of a plasma configuration consisting of a thin one-dimensional current sheet embedded into a two-dimensional background current sheet is studied. Drift modes developing in plasma as unstable waves along the current direction are considered. Dispersion relations for kink and sausage perturbation modes are obtained depending on the ratio of parameters of thin and background current sheets. It is shown that the existence of the background sheet results in a decrease in the instability growth rates and a significant increase in the perturbation wavelengths. The role of drift modes in the excitation of oscillations observed in the current sheet of the Earth's magnetotail is discussed.

  11. Focus on Organic Conductors

    Directory of Open Access Journals (Sweden)

    Shinya Uji, Takehiko Mori and Toshihiro Takahashi

    2009-01-01

    Full Text Available Organic materials are usually thought of as electrical insulators. Progress in chemical synthesis, however, has brought us a rich variety of conducting organic materials, which can be classified into conducting polymers and molecular crystals. Researchers can realize highly conducting molecular crystals in charge-transfer complexes, where suitable combinations of organic electron donor or acceptor molecules with counter ions or other organic molecules provide charge carriers. By means of a kind of chemical doping, the charge-transfer complexes exhibit high electrical conductivity and, thanks to their highly crystalline nature, even superconductivity has been observed. This focus issue of Science and Technology of Advanced Materials is devoted to the research into such 'organic conductors'The first organic metal was (TTF(TCNQ, which was found in 1973 to have high conductivity at room temperature and a metal–insulator transition at low temperatures. The first organic superconductor was (TMTSF2PF6, whose superconductivity under high pressures was reported by J´erome in 1980. After these findings, the research on organic conductors exploded. Hundreds of organic conductors have been reported, among which more than one hundred exhibit superconductivity. Recently, a single-component organic conductor has been found with metallic conductivity down to low temperatures.In these organic conductors, in spite of their simple electronic structures, much new physics has arisen from the low dimensionality. Examples are charge and spin density waves, characteristic metal–insulator transitions, charge order, unconventional superconductivity, superconductor–insulator transitions, and zero-gap conductors with Dirac cones. The discovery of this new physics is undoubtedly derived from the development of many intriguing novel organic conductors. High quality single crystals are indispensable to the precise measurement of electronic states.This focus issue

  12. Molecular dynamics studies of the melting of butane and hexane monolayers adsorbed on the basal-plane surface of graphite

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Newton, J. C.; Taub, H.

    1993-01-01

    The effect of molecular steric properties on the melting of quasi-two-dimensional solids is investigated by comparing results of molecular dynamics simulations of the melting of butane and hexane monolayers adsorbed on the basal-plane surface of graphite. These molecules differ only in their leng...

  13. Blowing the Fuse: Berry's Phase and Runaway Vibrations in Molecular Conductors

    DEFF Research Database (Denmark)

    Lu, Jing Tao; Brandbyge, Mads; Hedegård, P.

    2010-01-01

    We examine a molecular bridge connecting two metallic electrodes. We find that an electronic current passing across the bridge can cause a vibrational instability of the molecule, which ultimately can lead to a breakdown of the bridge. This instability is generated by a hitherto never considered...... mechanism, which surprisingly involves the quantum mechanical phase of the electronic waves, the "Berry phase". This mechanism works for highly conducting bridges, and contrary to breakdown by traditional joule heating, this instability is deterministic and occurs at certain critical voltages. We...

  14. Interplay between spin-density wave and 3 d local moments with random exchange in a molecular conductor

    Science.gov (United States)

    Kawaguchi, Genta; Maesato, Mitsuhiko; Komatsu, Tokutaro; Imakubo, Tatsuro; Kitagawa, Hiroshi

    2016-02-01

    We present the results of high-pressure transport measurements on the anion-mixed molecular conductors (DIETSe)2M Br2Cl2 [DIETSe = diiodo(ethylenedithio)tetraselenafulvalene; M =Fe , Ga]. They undergo a metal-insulator (M-I) transition below 9 K at ambient pressure, which is suppressed by applying pressure, indicating a spin-density-wave (SDW) transition caused by a nesting instability of the quasi-one-dimensional (Q1D) Fermi surface, as observed in the parent compounds (DIETSe)2M Cl4 (M =Fe , Ga). In the metallic state, the existence of the Q1D Fermi surface is confirmed by observing the Lebed resonance. The critical pressures of the SDW, Pc, of the M Br2Cl2 (M =Fe , Ga) salts are significantly lower than those of the the M Cl4 (M = Fe, Ga) salts, suggesting chemical pressure effects. Above Pc, field-induced SDW transitions appear, as evidenced by kink structures in the magnetoresistance (MR) in both salts. The FeBr2Cl2 salt also shows antiferromagnetic (AF) ordering of d spins at 4 K, below which significant spin-charge coupling is observed. A large positive MR change up to 150% appears above the spin-flop field at high pressure. At low pressure, in particular below Pc, a dip or kink structure appears in MR at the spin-flop field, which shows unconventionally large hysteresis at low temperature (T hysteresis region clearly decreases with increasing pressure towards Pc, strongly indicating that the coexisting SDW plays an important role in the enhancement of magnetic hysteresis besides the random exchange interaction.

  15. Molecular modeling, spectroscopic signature and NBO analysis of some building blocks of organic conductors.

    Science.gov (United States)

    Mukherjee, V

    2014-11-11

    Vibrational spectra with IR and Raman intensities in optimum state have been calculated for 2,2'-Bi-1,3-diselenole (commonly known as tetraselenafulvalene) and its halogen derivatives. All these calculations have been done by employing density functional theory (DFT) and second order Moller-Plesset perturbation theory (MP2) methods incorporated with suitable functionals and basis sets. Normal coordinate analysis has also been performed to calculate potential energy distributions (PEDs) to make a conspicuous assignment. The vibrational frequencies of all the four molecules have been assigned using PEDs and the results are compared with available values for the most similar molecules like tetrathiafulvalene. The molecular stability and bond strength have investigated by applying the Natural Bond Orbital (NBO) analysis. The energy gap between HOMO and LUMO is 2.041 eV for tetraselenafulvalene and it is slightly less than 2eV for halogen derivatives which implies that these molecules fall in the wide band gap semiconductor groups.

  16. Angle-dependent magnetoresistance oscillations in the quasi-two-dimensional organic conductor α-(BEDT- TTF)2NH4Hg(SCN)4: Origin of the difference in ground state between α-(BEDT- TTF)2NH4Hg(SCN)4 and α-(BEDT-TTF)2KHg(SCN)4

    Science.gov (United States)

    Hanasaki, N.; Kagoshima, S.; Miura, N.; Saito, G.

    2001-06-01

    We studied the difference between the ground states of α-(BEDT-TTF)2NH4Hg(SCN)4 and its isostructural compound α-(BEDT-TTF)2KHg(SCN)4 by measuring angle-dependent magnetoresistance. In the NH4 compound, we found resistance minima due to the Lebed resonances. These findings suggest the presence of the one-dimensional Fermi surface parallel to the b*c* plane. Detailed analyses of these resistance minima suggest a large warp in the planarlike Fermi surface along the c* axis. Second and higher harmonic components are necessary to describe the warping of the Fermi surface. We also analyzed the small closed-orbit effect, that is, the peak structure in the resistance for the magnetic field nearly parallel to the conducting plane. It was found that the corrugation in the Fermi surface perpendicular to the a*c* plane was also large in the NH4 compound compared to the K compound. We conclude that such large warps in the Fermi surface suppressed the nesting of the quasi-one-dimensional Fermi surface in the NH4 compound.

  17. Theoretical study of the zero-gap organic conductor α-(BEDT-TTF2I3

    Directory of Open Access Journals (Sweden)

    Akito Kobayashi, Shinya Katayama and Yoshikazu Suzumura

    2009-01-01

    Full Text Available The quasi-two-dimensional molecular conductor α-(BEDT-TTF2I3 exhibits anomalous transport phenomena where the temperature dependence of resistivity is weak but the ratio of the Hall coefficient at 10 K to that at room temperature is of the order of 104. These puzzling phenomena were solved by predicting massless Dirac fermions, whose motions are described using the tilted Weyl equation with anisotropic velocity. α-(BEDT-TTF2I3 is a unique material among several materials with Dirac fermions, i.e. graphene, bismuth, and quantum wells such as HgTe, from the view-points of both the structure and electronic states described as follows. α-(BEDT-TTF2I3 has the layered structure with highly two-dimensional massless Dirac fermions. The anisotropic velocity and incommensurate momenta of the contact points, ±k0, originate from the inequivalency of the BEDT-TTF sites in the unit cell, where ±k0 moves in the first Brillouin zone with increasing pressure. The massless Dirac fermions exist in the presence of the charge disproportionation and are robust against the increase in pressure. The electron densities on those inequivalent BEDT-TTF sites exhibit anomalous momentum distributions, reflecting the angular dependences of the wave functions around the contact points. Those unique electronic properties affect the spatial oscillations of the electron densities in the vicinity of an impurity. A marked behavior of the Hall coefficient, where the sign of the Hall coefficient reverses sharply but continuously at low temperatures around 5 K, is investigated by treating the interband effects of the magnetic field exactly. It is shown that such behavior is possible by assuming the existence of the extremely small amount of electron doping. The enhancement of the orbital diamagnetism is also expected. The results of the present research shed light on a new aspect of Dirac fermion physics, i.e. the emergence of unique electronic properties owing to the structure

  18. Mott-Anderson Transition in Molecular Conductors: Influence of Randomness on Strongly Correlated Electrons in the κ-(BEDT-TTF2X System

    Directory of Open Access Journals (Sweden)

    Takahiko Sasaki

    2012-05-01

    Full Text Available The Mott-Anderson transition has been known as a metal-insulator (MI transition due to both strong electron-electron interaction and randomness of the electrons. For example, the MI transition in doped semiconductors and transition metal oxides has been investigated up to now as a typical example of the Mott-Anderson transition for changing electron correlations by carrier number control in concurrence with inevitable randomness. On the other hand, molecular conductors have been known as typical strongly correlated electron systems with bandwidth controlled Mott transition. In this paper, we demonstrate our recent studies on the randomness effect of the strongly correlated electrons of the BEDT-TTF molecule based organic conductors. X-ray irradiation on the crystals introduces molecular defects in the insulating anion layer, which cause random potential modulation of the correlated electrons in the conductive BEDT-TTF layer. In combination with hydrostatic pressure, we are able to control the parameters for randomness and correlations for electrons approaching the Mott-Anderson transition.

  19. Diamagnetic phase transitions in two-dimensional conductors

    Science.gov (United States)

    Bakaleinikov, L. A.; Gordon, A.

    2014-11-01

    A theory describing the susceptibility amplitude and the magnetic induction bifurcation near the dHvA driven diamagnetic phase transitions in quasi two-dimensional (2D) organic conductors of the (ET)2X with X=Cu(NCS)2, KHg(SCN)4, I3, AuBr2, IBr2, etc. is presented. We show that there is a drastic increase in the temperature and magnetic field dependence of the susceptibility amplitude on approaching the diamagnetic phase transition point. Near the phase transition point the temperature and magnetic field dependences are fitted by the ones typical of the mean-field phase transition theory. These dependences confirm the long-range character of the magnetic interactions among the conduction electrons leading to diamagnetic phase transitions. We demonstrate that the magnetic induction splitting of nuclear magnetic resonance (NMR) and muon spin-rotation spectroscopy (μSR) lines due to two Condon domains decreases tending to zero on approaching the diamagnetic phase transition. This decrease is fitted by the temperature and magnetic field dependence of the susceptibility characteristic of the mean-field theory of phase transitions. Performing new susceptibility, NMR and μSR experiments will enable to detect diamagnetic phase transitions and Condon domains in quasi 2D metals.

  20. Magneto-optical studies of low-dimensional organic conductors

    Directory of Open Access Journals (Sweden)

    Hitoshi Ohta, Motoi Kimata and Yugo Oshima

    2009-01-01

    Full Text Available Our periodic orbit resonance (POR results on quasi-two-dimensional (q2D, highly anisotropic q2D and quasi-one-dimensional (q1D organic conductors are reviewed together with our rotational cavity magneto-optical measurement system. Higher order POR up to seventh order has been observed in the q2D system (BEDT-TTF2Br(DIA, and the experimental conditions to observe POR and the cyclotron resonance (CR are discussed. Highly anisotropic q2D Fermi surface (FS in β''-(BEDT-TTF(TCNQ, which was considered to have q1D FS previously, is proposed by our POR measurements, and the possible interpretations of other experimental results of β''-(BEDT-TTF(TCNQ are discussed assuming the highly anisotropic q2D FS. Finally, detailed q1D FS of (DMET2I3, obtained from our POR results, is discussed in connection with the typical q1D system (TMTSF2ClO4.

  1. Charge Transport in Antiferromagnetic Insulating Phase of Two-Dimensional Organic Conductor λ-(BETS)2FeCl4

    Science.gov (United States)

    Sugiura, Shiori; Shimada, Kazuo; Tajima, Naoya; Nishio, Yutaka; Terashima, Taichi; Isono, Takayuki; Kobayashi, Akiko; Zhou, Biao; Kato, Reizo; Uji, Shinya

    2016-06-01

    Resistance and dielectric constants have been measured in the antiferromagnetic insulating phase of the quasi-two-dimensional organic conductor λ-(BETS)2FeCl4 to understand charge transport. Nonlinear current-voltage characteristics are observed at low temperatures, which are explained by a charge transport model based on the electric-field dependent Coulomb potential between the thermally excited electron and hole. A small dip in the magnetic field dependence of the resistance is found at 1.2 T, which is ascribed to a spin-flop transition. The large difference between the in-plane and out-of-plane dielectric constants shows the two-dimensionality of the Coulomb potential, which is consistent with the charge transport model. The angular dependence of the metal-insulator transition field is determined, which suggests that the Zeeman effect of the 3d spins of the Fe ions plays an essential role.

  2. Electron Magnetic Resonance Fermi Surface Imaging. Applications to Organic Conductors and Sr2RuO4

    Science.gov (United States)

    Hill, S.; Kovalev, A.; Mola, M. M.; Palassis, C.; Mao, Z. Q.; Maeno, Y.; Qualls, J. S.

    We report detailed angle dependent studies of the metallic state microwave (40 to 200 GHz) magneto-conductivity of single crystal samples of the α-(BEDT-TTF)2KHg(SCN)4 organic charge density wave conductor, and the perovskite superconductor Sr2RuO4. We observe series' of resonant absorptions which we attribute to periodic orbit resonances - a phenomenon closely related to cyclotron resonance. By performing measurements on several samples, and in different electromagnetic field configurations, we are able to couple to different orbital modes (+ harmonics), which derive from deformations (warpings) of the quasi-one and quasi-two-dimensional Fermi surfaces of these compounds. These studies provide vital information concerning interlayer dispersion which, in turn, affects the Fermi surface nesting characteristics which are believed to play a crucial role in the low temperature physics of these exotic materials.

  3. Conductive Mechanism of Organic Conductor

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Organic conductor is a kind of organic compound which has special electronic and magnetic properties. The research of the organic compounds has received considerable attention because of their potential applications in many areas. The molecular conductive units are theoretically investigated as well as their energy gap and charge distribution. The relationship of conductivity and micro-mechanism is discussed.

  4. Diamagnetic phase transitions in two-dimensional conductors

    Energy Technology Data Exchange (ETDEWEB)

    Bakaleinikov, L.A., E-mail: bakal.ammp@mail.ioffe.ru [A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg 194021 (Russian Federation); Department of Mathematics and Physics, Faculty of Natural Sciences, University of Haifa, Campus Oranim, Tivon 36006 (Israel); Gordon, A. [Department of Mathematics and Physics, Faculty of Natural Sciences, University of Haifa, Campus Oranim, Tivon 36006 (Israel)

    2014-11-15

    A theory describing the susceptibility amplitude and the magnetic induction bifurcation near the dHvA driven diamagnetic phase transitions in quasi two-dimensional (2D) organic conductors of the (ET){sub 2}X with X=Cu(NCS){sub 2},KHg(SCN){sub 4},I{sub 3},AuBr{sub 2},IBr{sub 2}, etc. is presented. We show that there is a drastic increase in the temperature and magnetic field dependence of the susceptibility amplitude on approaching the diamagnetic phase transition point. Near the phase transition point the temperature and magnetic field dependences are fitted by the ones typical of the mean-field phase transition theory. These dependences confirm the long-range character of the magnetic interactions among the conduction electrons leading to diamagnetic phase transitions. We demonstrate that the magnetic induction splitting of nuclear magnetic resonance (NMR) and muon spin-rotation spectroscopy (μSR) lines due to two Condon domains decreases tending to zero on approaching the diamagnetic phase transition. This decrease is fitted by the temperature and magnetic field dependence of the susceptibility characteristic of the mean-field theory of phase transitions. Performing new susceptibility, NMR and μSR experiments will enable to detect diamagnetic phase transitions and Condon domains in quasi 2D metals. - Highlights: • A theory of diamagnetic phase transitions (DPTs) is presented in 2D organic conductors. • The behaviour of the susceptibility amplitude and the induction splitting is shown near the DPT. • The calculated quantities are described by the mean-field theory of phase transitions.

  5. Photoconduction in CDW conductors

    Energy Technology Data Exchange (ETDEWEB)

    Zaitsev-Zotov, S.V., E-mail: serzz@cplire.ru [Kotel' nikov IRE RAS, Mokhovaya 11, Bld. 7, 125009 Moscow (Russian Federation); Minakova, V.E.; Nasretdinova, V.F.; Zybtsev, S.G. [Kotel' nikov IRE RAS, Mokhovaya 11, Bld. 7, 125009 Moscow (Russian Federation)

    2012-06-01

    Photoconduction study of quasi-1D conductors allows to distinguish between the single-particle and collective linear conduction, investigate the effect of screening on collective transport and obtain interesting new details of the electronic energy structure of pure and doped CDW conductors. Here we present results of photoconduction study in quasi-1D conductors o-TaS{sub 3}, K{sub 0.3}MoO{sub 3}, and NbS{sub 3}(I).

  6. Towards Single-component Molecular Conductor [Ni(dmit)2] by Charge Disproportionation:2[Ni(dmit)2]-0.5 →[Ni(dmit)2 ]+ [Ni(dmit)2]-

    Institute of Scientific and Technical Information of China (English)

    Qi FANG; Hong LEI; Wen XU

    2003-01-01

    A new method of synthesizing single-component molecular conductor [Ni(dmit)2] by the reaction 2(Me4N)[Ni(dmit)2]2→[Ni(dmit)2] + (Me4N)[Ni(dmit)2] is reported. [Ni(dmit)2] exhibits a semiconductive behavior above 167 K, while from 167 K down to the measuring limit of 60 K, it exhibits metallic conductivity.

  7. Variation of diffusivity with the cation radii in molten salts of superionic conductors containing iodine anion: A molecular dynamics study

    Indian Academy of Sciences (India)

    Srinivasa R Varanasi; S Yashonath

    2012-01-01

    A molecular dynamics study of the dependence of diffusivity of the cation on ionic radii in molten AgI is reported.We have employed modified Parinello-Rahman-Vashistha interionic pair potential proposed by Shimojo and Kobayashi. Our results suggest that the diffusivity of the cation exhibits an increase followed by a decrease as the ionic radius is increased. Several structural and dynamical properties are reported.

  8. Doping of Semi Conductors

    Directory of Open Access Journals (Sweden)

    V. V. Agashe

    1960-07-01

    Full Text Available Most of the semi-conductors are formed by addition of foreign substances in an insulator. This is called 'Doping'. These doped semi-conductors today are widely used in many electrical devices. Some of them are rectifiers, transistors, thermistors, oxides cathodes and photo-sensitive elements. This paper reviews the fundamental concept of impurity in semi-conductors and recent work on doping of the latter. Purification methods are described in the case of group IV elements and semi-conducting intermetallic compounds. Results of different physical measurements have been discussed in order to understand the role of 'doping'.

  9. Organic Conductors: Evidence for Correlation Effects in Infrared Properties

    DEFF Research Database (Denmark)

    Jacobsen, Claus Schelde; Johannsen, Ib; Bechgaard, Klaus

    1984-01-01

    The infrared conductivities of four organic conductors with partially filled one-electron bands are compared. The behavior ranges from near Drude type in the best metal to semiconductorlike in the moderate conductor. Electron-molecular-vibration coupling effects of varying degree are seen in all...

  10. Cyclotron resonance and De Haas-Van Alphen effect in (BEDT-TTF) sub 8 Hg sub 4 Cl sub 1 sub 2 (C sub 6 H sub 5 Cl) sub 2 organic conductor

    CERN Document Server

    Voskobojnikov, I B; Samarin, N A; Cluchanko, N E; Lyubovskaya, R N; Moshchalkov, V V

    2002-01-01

    Within 0.33-1.44 K temperature range at B <= 50 T magnetic field values one measured the De Haas-Van Alphen effect for (BEDT-TTF) sub 8 Hg sub 4 Cl sub 1 sub 2 (C sub 6 H sub 5 Cl) sub 2 organic quasi-two-dimensional conductor. Analysis of quantum oscillations with regard to data on cyclotron resonance derived for 40-120 GHz frequency interval enabled to determine that a complex spectrum of quantum oscillations was formed by alpha approx 256 T and beta approx 670-610 T fundamental frequencies as well as, by combination and multiple frequencies. It is shown that nature of temperature rearrangement of oscillation spectrum may be interpreted in terms of model taking account of occurrence of magnetic phase transition at T sub c approx 0.9 K and proximity of a fundamental frequency with m* = 1.48m sub 0 efficient mass to the spin dumping condition

  11. Determination of Band-filling Change in the Two-dimensional Organic Conductor, τ-(EDO-S,S-DMEDT-TTF)2(AuBr2)1+y, (y ≤ 0.875) by the Quantum Oscillation of Magnetoresistance

    Science.gov (United States)

    Yoshino, Harukazu; Murata, Keizo; Nakanishi, Tsutomu; Li, Lin; Choi, Eun Sang; Graf, David; Brooks, James S.; Nogami, Yoshio; Papavassiliou, George C.

    2005-01-01

    The effect of thermal treatment on the transport properties is studied for a two-dimensional organic conductor τ-(EDO-S,S-DMEDT-TTF)2(AuBr2)1+y, (y ≤ 0.875). The temperature dependence of the electric resistivity below room temperature was found to be changed from metallic down to low temperature to semiconducting by heating up to 420 K. One of the two frequencies of Shubnikov--de Haas oscillations are found to be different between the non-heated and heated parts from a single crystal, while no evidence of structural change in X-ray photograph was observed. The present result clearly shows that nominal valence or band filling can be controlled by simple thermal treatment for the quasi-two-dimensional organic metal. The mechanism of the change in the band filling is discussed in terms of anion decomposition.

  12. Plasmonic transparent conductors

    Science.gov (United States)

    Liapis, Andreas C.; Sfeir, Matthew Y.; Black, Charles T.

    2016-09-01

    Many of today's technological applications, such as solar cells, light-emitting diodes, displays, and touch screens, require materials that are simultaneously optically transparent and electrically conducting. Here we explore transparent conductors based on the excitation of surface plasmons in nanostructured metal films. We measure both the optical and electrical properties of films perforated with nanometer-scale features and optimize the design parameters in order to maximize optical transmission without sacrificing electrical conductivity. We demonstrate that plasmonic transparent conductors can out-perform indium tin oxide in terms of both their transparency and their conductivity.

  13. 76 FR 69801 - Conductor Certification

    Science.gov (United States)

    2011-11-09

    ... definition of ``conductor'' is a fundamental element of the conductor certification regulation and FRA does... and 219. G. Vision and Hearing Acuity BLET/UTU commented that proposed Sec. 242.117(k) should...

  14. Well Conductor Strain Monitoring

    Science.gov (United States)

    2014-05-06

    comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE JUL 2014 2. REPORT TYPE 3. DATES...849,429; filed on June 26, 2013 by the inventor, Dr. Anthony Ruffa and entitled “ SUBSEA WELL CONDUCTOR STRAIN MONITORING”. STATEMENT OF

  15. Theory of Superionic Conductors

    Science.gov (United States)

    1981-09-01

    TYPE OF REPORT 6 PERIOO COVERED Final Technical )THEORY OF SUPERIONIC CONDUCTORS 9/30/76 to 9/30/81 SVIERFORMI- 4G ORG REPURT NUMBER AI I 1,701 ,- S...several mathematical models of ion and electron conduction in many-particle systems. . DD AN 1473 SECURIT "-CLASSIiCAt N OF THIS PAGE 1 (Wen D E / / A

  16. The CMS conductor

    CERN Document Server

    Blau, Bertrand; Curé, B; Folch, R; Hervé, A; Horváth, I L; Kircher, F; Musenich, R; Neuenschwander, J; Riboni, P; Seeber, B; Tavares, S; Sgobba, Stefano; Smith, R P

    2002-01-01

    The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4 T, the magnetic length is 12.5 m and the free bore is 6 m. The magnetic field is achieved by means of a four-layer superconducting solenoid. The stored magnetic energy is 2.7 GJ at nominal current of 20 kA (at 4.5 K operating temperature). The coil is wound from a high purity aluminum- stabilized Rutherford type conductor. Unlike other existing Al- stabilized thin solenoids, the structural integrity of the CMS coil is ensured both by the Al-alloy reinforcement welded to the conductor and an external support cylinder. The flat NbTi cable is embedded in high purity aluminum by a continuous co-extrusion process. (7 refs).

  17. Physics of superionic conductors

    CERN Document Server

    1979-01-01

    Superionic conductors are solids whose ionic conductivities approach, and in some cases exceed, those of molten salts and electrolyte solutions. This implies an un­ usual state of matter in which some atoms have nearly liquidlike mobility while others retain their regular crystalline arrangement. This liquid-solid duality has much appeal to condensed matter physicists, and the coincident development of powerful new methods for studying disordered solids and interest in superionic conductors for technical applications has resulted in a new surge of activity in this venerable field. It is the purpose of this book to summarize the current re­ search in the physics of superionic conduction. with special emphasis on those aspects which set these materials apart from other solids. The volume is aimed to­ wards the materials community and will, we expect, stimulate further research on these potentially useful substances. The usual characterization of the superionic phase lists high ionic conductivity; low activat...

  18. Plasmonic Graphene Transparent Conductors

    Science.gov (United States)

    2012-01-01

    www.MaterialsViews.com www.advopticalmat.de FU LL P A P ER Guowei Xu,* Jianwei Liu, Qian Wang , Rongqing Hui, Zhijun Chen, Victor A. Maroni, and Judy Wu Plasmonic...decision, unless so designated by other documentation. 12. DISTRIBUTION AVAILIBILITY STATEMENT Approved for public release; distribution is unlimited. UU...Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS surface plasmon, graphene, transparent conductors Guowei Xu, Jianwei Liu, Qian

  19. The CMS conductor

    CERN Document Server

    Horváth, I L; Marti, H P; Neuenschwander, J; Smith, R P; Fabbricatore, P; Musenich, R; Calvo, A; Campi, D; Curé, B; Desirelli, Alberto; Favre, G; Riboni, P L; Sgobba, Stefano; Tardy, T; Sequeira-Lopes-Tavares, S

    2000-01-01

    The Compact Muon Solenoid (CMS) is one of the experiments, which are being designed in the framework of the Large Hadron Collider (LHC) project at CERN, the design field of the CMS magnet is 4 T, the magnetic length is 13 m and the aperture is 6 m. This high magnetic field is achieved by means of a 4 layer, 5 modules superconducting coil. The coil is wound from an Al-stabilized Rutherford type conductor. The nominal current of the magnet is 20 kA at 4.5 K. In the CMS coil the structural function is ensured, unlike in other existing Al-stabilized thin solenoids, both by the Al-alloy reinforced conductor and the external former. In this paper the retained manufacturing process of the 50-km long reinforced conductor is described. In general the Rutherford type cable is surrounded by high purity aluminium in a continuous co-extrusion process to produce the Insert. Thereafter the reinforcement is joined by Electron Beam Welding to the pure Al of the insert, before being machined to the final dimensions. During the...

  20. Alternative HTS coated conductors

    Science.gov (United States)

    Blaugher, R. D.; Bhattacharya, R. N.; Chen, J.; Padmanabhan, R.

    2002-10-01

    The availability of Bi-2223 high-temperature-superconductor (HTS) powder-in-tube (PIT) tape, with acceptable performance for long lengths, has provided the ability to construct a wide range of HTS electric power components. As a result, there are major worldwide projects in developing HTS electric power components for demonstration in a utility environment. Utility acceptance for superconducting power equipment will depend on several key factors: improved system performance, lower life-cycle costs, higher efficiency versus conventional technology, reliability and maintenance comparable to conventional power equipment, and a competitive installed cost. The latter is impacted by the current high cost of HTS conductors, which must be lowered to costs comparable to conventional Nb-Ti wire, i.e., $2-5/kAm. The present performance and cost of state-of-the-art Bi-2223 HTS tape, although acceptable for prototype construction, is viewed as a major deterrent that may compromise eventual commercialization for most of these electric power devices. The so-called second-generation coated conductor development, with emphasis on conductors employing HTS YBCO films, is viewed as the solution to this performance and cost issue. The potential for the Tl, Hg, and Bi-oxide superconductors for producing an HTS tape as alternatives to Bi-2223 PIT (and YBCO) will be discussed with some recent results on Bi-2212 “coated conductor” development.

  1. Direct observation of strong localization of quasi-two-dimensional light waves

    DEFF Research Database (Denmark)

    Bozhevolnyi, Sergey I.

    1999-01-01

    Scattering of surface plasmon polaritons on rough metal surfaces is investigated by using scanning near-field optical microscopy. Different scattering regimes, i.e. single, double and multiple scattering, are observed and related to the spatial Fourier spectra of the corresponding near......-field optical images. For the regime of strong multiple scattering, the near-field optical images exhibit spatially localized (within 150-250 nm) intensity enhancement by 10-50 times. This feature is attributed to strong localization of surface polaritons due to interference effects in multiple scattering...... caused by surface roughness. Similar bright light spots are observed with light scattering by silver colloid clusters deposited on glass substrates. Differences and similarities in these scattering phenomena are discussed....

  2. Uncertainty analysis of quasi-two-dimensional flow simulation in compound channels with overbank flows

    OpenAIRE

    Riahi-Madvar, Hossien; Ayyoubzadeh, Seyed Ali; Namin, Masoud Montazeri; Seifi, Akram

    2011-01-01

    Flow in compound channels with overbank flows becomes more complex because of shear interactions between flows in main channel and flood plains, lateral momentum transfer and secondary flows. Compound channels have interesting applications in flood control, civil engineering and environmental management. Because it is difficult to obtain sufficiently accurate and comprehensive understandings of flow in natural compound rivers, the developed models of flow in overbank flows have many uncertain...

  3. Experimentally determining the exchange parameters of quasi-two dimensional Heisenbert magnets

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, John [Los Alamos National Laboratory; Sengupta, P [Los Alamos National Laboratory; Mcdonald, R D [Los Alamos National Laboratory; Cox, S [Los Alamos National Laboratory; Harrison, N [Los Alamos National Laboratory; Goddard, P A [UNIV OF OXFORD; Lancaster, T [UNIV OF OXFORD; Blundell, S J [UNIV OF OXFORD; Pratt, F L [RUTHERFORD APPLETON LAB; Manson, J L [EASTERN WASHINGTON UNIV; Southerland, H I [EASTERN WASHINGTON UNIV; Schlueter, J A [ANL

    2008-01-01

    Though long-range magnetic order cannot occur at temperatures T > 0 in a perfect two-dimensional (2D) Heisenberg magnet, real quasi-2D materials will invariably possess nonzero inter-plane coupling J{sub {perpendicular}} driving the system to order at elevated temperatures. This process can be studied using quantum Monte Carlo calculations. However, it is difficult to test the results of these calculations experimentally since for highly anisotropic materials in which the in-plane coupling is comparable with attainable magnetic fields J{sub {perpendicular}} is necessarily very small and inaccessible directly. In addition, because of the large anisotropy, the Neel temperatures are low and difficult to determine from thermodynamic measurements. Here, we present an elegant method of assessing the calculations via two independent experimental probes: pulsed-field magnetization in fields of up to 85 T, and muon-spin rotation.

  4. Interactions of a Quasi-Two-Dimensional Vortex with a Stationary and Oscillating Leading-Edge

    Science.gov (United States)

    1996-07-01

    together. I also thank mi hermano Fernando and the members of Hamilton Branch and Kutztown Ward for the fun times we’ve shared that have helped to...19 v K 1.8.2 Summary of Research Objectives .................................................. 20 1.9 Outline of...absence of a uniform flow the vortex will convect to the left with self-induced speed Vs=ic/2a, where K is the vortex strength (F = 2itic) and a is the

  5. Observations of the sedimentation of individual particles in a quasi-two dimensional system

    Science.gov (United States)

    Ramos, Eduardo; Lee, Andrew; Goldman, Daniel; Swinney, Harry

    2002-11-01

    We report observations of single sedimenting acrylic spheres (diameter = 3.175 mm, relative density = 1.19) in a vertical Hele-Shaw cell formed by two parallel glass plates and filled with water. The distance between walls of the cell varies from 1.1 to 1.3 sphere diameters; the corresponding sedimenting Reynolds number varies from 220 to 300. In the narrower cell, a wake was formed by an attached vortical region behind the sphere with two asymetrical branches. These branches oscillated and shed vortices alternately; this structure is similar to the Von Karman vortex street generated by a fixed cylinder exposed to a constant flow at approximately the same Reynolds number. In contrast, the wake of a sphere falling in a cell with a gap of 1.3 diameters was similar to that for a sphere in an infinite system at Reynolds numbers slightly larger than the threshhold for the onset of periodic wake oscillations (Re 300): the sphere sheds vortex loops, which are separated by counterotating pairs of vortex filaments.

  6. Dephasing in the quasi-two-dimensional exciton-biexciton system

    DEFF Research Database (Denmark)

    Langbein, Wolfgang Werner; Hvam, Jørn Märcher

    2000-01-01

    The polarization decay in the exciton-biexciton system of a homogeneously broadened single quantum well is studied by transient four-wave mixing. All three decay rates in the exciton-biexciton three-level system are deduced. The relation between the rates unravels correlations between scattering...... processes of excitons and biexcitons. Density and temperature dependences show that the involved processes are mainly radiative decay and phonon scattering. The radiative decay rate of the biexcitons is found to be comparable to the one of the excitons, and the involved spontaneous photon emissions from...

  7. Motility of \\textit{Escherichia coli} in a quasi-two-dimensional porous medium

    CERN Document Server

    Sosa-Hernández, Juan Eduardo; Santana-Solano, Jesús

    2016-01-01

    Bacterial migration through confined spaces is critical for several phenomena like: biofilm formation, bacterial transport in soils, and bacterial therapy against cancer . In the present work, \\textit{E. coli} (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-2-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98 $\\mu m$ spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing trajectory parameters like: instantaneous velocity and turn angle, as well as mean squared displacement, we were able to quantify the effects that different latex particle concentrations have upon bacterial motility. To better understand our results, bacterial trajectories were simulated by means of a phenomenological random-walk model (developed ad hoc), and the simulated ...

  8. Coexistence of superconductivity and density waves in quasi-two-dimensional metals

    Energy Technology Data Exchange (ETDEWEB)

    Ismer, Jan-Peter

    2011-06-03

    This dissertation deals with the high-temperature superconductivity in the hole- and electron-doped copper superconductors. In the first part, superconducting phases are investigated on a background of different types of density waves. Singlet superconductivity is studied with s- and d-wave symmetry on a background of spin, charge or D-density waves with respect to stability as well as phase structure and impulse dependence of the gap function. In the second part, the dynamic spin susceptibility for different phases is calculated and compared with experimental data extracted from results of inelastic neutron scattering experiments. The observed phases are d-wave superconductivity, D-density wave, and coexistence of the two. For d-wave superconductivity, the influence of a magnetic field parallel to the copper oxide layer and the temperature development of the susceptibility when for T >> T{sub c} a spin density wave phase is present are investigated. [German] Diese Dissertation beschaeftigt sich mit der Hochtemperatursupraleitung in den loch- und elektron-dotierten Kuprat-Supraleitern. Im ersten Teil der Arbeit werden supraleitende Phasen auf einem Hintergrund verschiedener Typen von Dichtewellen untersucht. Es wird Singlett-Supraleitung mit s- und d-Wellen-Symmetrie auf einem Hintergrund von Spin-, Ladungs- oder D-Dichtewelle hinsichtlich Stabilitaet sowie Phasenstruktur und Impulsabhaengigkeit der Gapfunktion untersucht. Im zweiten Teil wird die dynamische Spinsuszeptibilitaet fuer verschiedene Phasen berechnet und mit experimentellen Daten verglichen, die aus Ergebnissen von Inelastischen Neutronenstreuungsexperimenten extrahiert wurden. Die betrachteten Phasen sind d-Wellen-Supraleitung, D-Dichtewelle und Koexistenz der beiden. Fuer d-Wellen-Supraleitung werden der Einfluss eines Magnetfelds parallel zur Kupferoxidschicht und die Temperaturentwicklung der Suszeptibilitaet, wenn fuer T >> T{sub c} eine Spin-Dichtewelle-Phase vorliegt, untersucht.

  9. Bubble statistics and coarsening dynamics for quasi-two-dimensional foams with increasing liquid content.

    Science.gov (United States)

    Roth, A E; Jones, C D; Durian, D J

    2013-04-01

    We report on the statistics of bubble size, topology, and shape and on their role in the coarsening dynamics for foams consisting of bubbles compressed between two parallel plates. The design of the sample cell permits control of the liquid content, through a constant pressure condition set by the height of the foam above a liquid reservoir. We find that in the scaling regime, all bubble distributions are independent not only of time, but also of liquid content. For coarsening, the average rate decreases with liquid content due to the blocking of gas diffusion by Plateau borders inflated with liquid; we achieve a factor of 4 reduction from the dry limit. By observing the growth rate of individual bubbles, we find that von Neumann's law becomes progressively violated with increasing wetness and decreasing bubble size. We successfully model this behavior by explicitly incorporating the border-blocking effect into the von Neumann argument. Two dimensionless bubble shape parameters naturally arise, one of which is primarily responsible for the violation of von Neumann's law for foams that are not perfectly dry.

  10. Final Report - Composite Fermion Approach to Strongly Interacting Quasi Two Dimensional Electron Gas Systems

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, John

    2009-11-30

    Work related to this project introduced the idea of an effective monopole strength Q* that acted as the effective angular momentum of the lowest shell of composite Fermions (CF). This allowed us to predict the angular momentum of the lowest band of energy states for any value of the applied magnetic field simply by determining N{sub QP} the number of quasielectrons (QE) or quasiholes (QH) in a partially filled CF shell and adding angular momenta of the N{sub QP} Fermions excitations. The approach reported treated the filled CF level as a vacuum state which could support QE and QH excitations. Numerical diagonalization of small systems allowed us to determine the angular momenta, the energy, and the pair interaction energies of these elementary excitations. The spectra of low energy states could then be evaluated in a Fermi liquid-like picture, treating the much smaller number of quasiparticles and their interactions instead of the larger system of N electrons with Coulomb interactions.

  11. Quantum critical response function in quasi-two-dimensional itinerant antiferromagnets

    Science.gov (United States)

    Varma, C. M.; Zhu, Lijun; Schröder, Almut

    2015-10-01

    We reexamine the experimental results for the magnetic response function χ''(q ,E ,T ) for q around the antiferromagnetic vectors Q , in the quantum-critical region, obtained by inelastic neutron scattering, on an Fe-based superconductor and on a heavy-fermion compound. The motivation is to compare the results with a recent theory, which shows that the fluctuations in a generic antiferromagnetic model for itinerant fermions map to those in the universality class of the dissipative quantum-XY model. The quantum-critical fluctuations in this model, in a range of parameters, are given by the correlations of spatial and temporal topological defects. The theory predicts a χ''(q ,E ,T ) (i) which is a separable function of (q -Q ) and of (E ,T ) , (ii) at criticality, the energy-dependent part is ∝tanh(E /2 T ) below a cutoff energy, (iii) the correlation time departs from its infinite value at criticality on the disordered side by an essential singularity, and (iv) the correlation length depends logarithmically on the correlation time, so that the dynamical critical exponent z is ∞ . The limited existing experimental results are found to be consistent with the first two unusual predictions from which the linear dependence of the resistivity on T and the T lnT dependence of the entropy also follow. More experiments are suggested, especially to test the theory of variations on the correlation time and length on the departure from criticality.

  12. Quantum Phase Transition in Quasi-two-dimensional Heisenberg Antiferromagnet with Single-Ion Anisotropy

    Institute of Scientific and Technical Information of China (English)

    JI An-Chun; TIAN Guang-Shan

    2007-01-01

    In the present paper, we investigate the quantum phase transition in a spatially anisotropic antiferromagnetic Heisenberg model of S = 1 with single-ion energy anisotropy. By using the Schwinger boson representation, we calculate the Gaussian correction to the critical value Jc⊥ caused by quantum spin fluctuations. We find that, for the positive single-ion energy, a nonzero value of Jc⊥ is always needed to stabilize the antiferromagnetic long-range order in this model. It resolves a difference among literature and shows clearly that the effect of quantum fluctuations may qualitatively change a result obtained by the mean-field theories on lower-dimensional systems.

  13. Spin transport of the frustrated quasi-two-dimensional XY-like antiferromagnet

    Science.gov (United States)

    Lima, L. S.

    2017-01-01

    We use the Self Consistent Harmonic Approximation together with the Kubo formalism of the Linear Response Theory to study the spin transport in the two-dimensional frustrated Heisenberg antiferromagnet in a square lattice with easy-plane ion single anisotropy. The regular part of the spin conductivity σreg(ω) is determined for several values of the critical ion single parameter Dc, that separates the low D region from the large D quantum paramagnetic phase. We have obtained an abrupt change in the spin conductivity in the discontinuity points of the graphic Dc vs. η, where the system presents a quantum phase transition.

  14. Layer-dependent anisotropic electronic structure of freestanding quasi-two-dimensional Mo S 2

    KAUST Repository

    Hong, Jinhua

    2016-02-29

    The anisotropy of the electronic transition is a well-known characteristic of low-dimensional transition-metal dichalcogenides, but their layer-thickness dependence has not been properly investigated experimentally until now. Yet, it not only determines the optical properties of these low-dimensional materials, but also holds the key in revealing the underlying character of the electronic states involved. Here we used both angle-resolved electron energy-loss spectroscopy and spectral analysis of angle-integrated spectra to study the evolution of the anisotropic electronic transition involving the low-energy valence electrons in the freestanding MoS2 layers with different thicknesses. We are able to demonstrate that the well-known direct gap at 1.8 eV is only excited by the in-plane polarized field while the out-of-plane polarized optical gap is 2.4 ± 0.2 eV in monolayer MoS2. This contrasts with the much smaller anisotropic response found for the indirect gap in the few-layer MoS2 systems. In addition, we determined that the joint density of states associated with the indirect gap transition in the multilayer systems and the corresponding indirect transition in the monolayer case has a characteristic three-dimensional-like character. We attribute this to the soft-edge behavior of the confining potential and it is an important factor when considering the dynamical screening of the electric field at the relevant excitation energies. Our result provides a logical explanation for the large sensitivity of the indirect transition to thickness variation compared with that for the direct transition, in terms of quantum confinement effect.

  15. Spin eigen-states of Dirac equation for quasi-two-dimensional electrons

    Energy Technology Data Exchange (ETDEWEB)

    Eremko, Alexander, E-mail: eremko@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Sttr., 14-b, Kyiv, 03680 (Ukraine); Brizhik, Larissa, E-mail: brizhik@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Sttr., 14-b, Kyiv, 03680 (Ukraine); Loktev, Vadim, E-mail: vloktev@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, Metrologichna Sttr., 14-b, Kyiv, 03680 (Ukraine); National Technical University of Ukraine “KPI”, Peremohy av., 37, Kyiv, 03056 (Ukraine)

    2015-10-15

    Dirac equation for electrons in a potential created by quantum well is solved and the three sets of the eigen-functions are obtained. In each set the wavefunction is at the same time the eigen-function of one of the three spin operators, which do not commute with each other, but do commute with the Dirac Hamiltonian. This means that the eigen-functions of Dirac equation describe three independent spin eigen-states. The energy spectrum of electrons confined by the rectangular quantum well is calculated for each of these spin states at the values of energies relevant for solid state physics. It is shown that the standard Rashba spin splitting takes place in one of such states only. In another one, 2D electron subbands remain spin degenerate, and for the third one the spin splitting is anisotropic for different directions of 2D wave vector.

  16. Critical behavior of quasi-two-dimensional semiconducting ferromagnet Cr2Ge2Te6

    Science.gov (United States)

    Liu, Yu; Petrovic, C.

    2017-08-01

    The critical properties of the single-crystalline semiconducting ferromagnet Cr2Ge2Te6 were investigated by bulk dc magnetization around the paramagnetic to ferromagnetic phase transition. Critical exponents β =0.200 ±0.003 with a critical temperature Tc=62.65 ±0.07 K and γ =1.28 ±0.03 with Tc=62.75 ±0.06 K are obtained by the Kouvel-Fisher method whereas δ =7.96 ±0.01 is obtained by a critical isotherm analysis at Tc=62.7 K. These critical exponents obey the Widom scaling relation δ =1 +γ /β , indicating self-consistency of the obtained values. With these critical exponents the isotherm M (H ) curves below and above the critical temperatures collapse into two independent universal branches, obeying the single scaling equation m =f±(h ) , where m and h are renormalized magnetization and field, respectively. The determined exponents match well with those calculated from the results of the renormalization group approach for a two-dimensional Ising system coupled with a long-range interaction between spins decaying as J (r ) ≈r-(d +σ ) with σ =1.52 .

  17. Nanofluidic electrokinetics in quasi-two-dimensional branched U-turn channels

    NARCIS (Netherlands)

    Parikesit, G.O.F.

    2008-01-01

    Lab-on-a-Chip (LOC) is a new technology focused on analyzing and controlling flows of fluids, ions, and (bio) particles on the nanometer and micrometer scales, allowing us to shrink a complete fluid-based laboratory into a coin-sized instrumentation. In this thesis, we study a novel fluidic structur

  18. Three-dimensional vortex solitons in quasi-two-dimensional lattices.

    Science.gov (United States)

    Leblond, Hervé; Malomed, Boris A; Mihalache, Dumitru

    2007-08-01

    We consider the three-dimensional (3D) Gross-Pitaevskii or nonlinear Schrödinger equation with a quasi-2D square-lattice potential (which corresponds to the optical lattice trapping a self-attractive Bose-Einstein condensate, or, in some approximation, to a photonic-crystal fiber, in terms of nonlinear optics). Stable 3D solitons, with embedded vorticity S=1 and 2, are found by means of the variational approximation and in a numerical form. They are built, basically, as sets of four fundamental solitons forming a rhombus, with phase shifts piS2 between adjacent sites, and an empty site in the middle. The results demonstrate two species of stable 3D solitons, which were not studied before, viz., localized vortices ("spinning light bullets," in terms of optics) with S>1 , and vortex solitons (with any S not equal 0 ) supported by a lattice in the 3D space. Typical scenarios of instability development (collapse or decay) of unstable localized vortices are identified too.

  19. Motility of \\textit{Escherichia coli} in a quasi-two-dimensional porous medium

    OpenAIRE

    Sosa-Hernández, Juan Eduardo; Zerón, Moisés Santillán; Santana-Solano, Jesús

    2016-01-01

    Bacterial migration through confined spaces is critical for several phenomena like: biofilm formation, bacterial transport in soils, and bacterial therapy against cancer . In the present work, \\textit{E. coli} (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-2-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98...

  20. Quasi-two-dimensional optomechanical crystals with a complete phononic bandgap

    CERN Document Server

    Alegre, Thiago P Mayer; Winger, Martin; Painter, Oskar

    2010-01-01

    A fully planar two-dimensional optomechanical crystal formed in a silicon microchip is used to create a structure devoid of phonons in the GHz frequency range. A nanoscale photonic crystal cavity is placed inside the phononic bandgap crystal in order to probe the properties of the localized acoustic modes. By studying the trends in mechanical damping, mode density, and optomechanical coupling strength of the acoustic resonances over an array of structures with varying geometric properties, clear evidence of a complete phononic bandgap is shown.

  1. Conditioning flat conductors for flat conductor cable production

    Science.gov (United States)

    1968-01-01

    Apparatus can straighten, anneal, clean, and a tension to stretch a cable one percent to assure uniform cross-sectional area. A conductor passes through temperature controlled distilled water and through a toroid coil. As The conductor enters the water, steam performs the cleaning action. Quenching and annealing also take place.

  2. Oxygen ion conductors

    Directory of Open Access Journals (Sweden)

    Stephen J Skinner

    2003-03-01

    A very interesting subgroup of this class of materials are the oxides that display oxygen ion conductivity. As well as the intrinsic interest in these materials, there has been a continued drive for their development because of the promise of important technological devices such as the solid oxide fuel cell (SOFC, oxygen separation membranes, and membranes for the conversion of methane to syngas1. All of these devices offer the potential of enormous commercial and ecological benefits provided suitable high performance materials can be developed. In this article we will review the materials currently under development for application in such devices with particular reference to some of the newly discovered oxide ion conductors.

  3. Floating insulated conductors for heating subsurface formations

    Science.gov (United States)

    Burns, David; Goodwin, Charles R.

    2014-07-29

    A heating system for a subsurface formation includes a conduit located in a first opening in the subsurface formation. Three electrical conductors are located in the conduit. A return conductor is located inside the conduit. The return conductor is electrically coupled to the ends of the electrical conductors distal from the surface of the formation. Insulation is located inside the conduit. The insulation electrically insulates the three electrical conductors, the return conductor, and the conduit from each other.

  4. Strong Electron Correlation in the High-Temperature Phase of (EDO-TTF)2PF6 as a Quasi-One-Dimensional Molecular Conductor

    Science.gov (United States)

    Iwano, Kaoru; Shimoi, Yukihiro

    2010-10-01

    We focus on the electronic property of the high-temperature phase of (EDO-TTF)2PF6. Applying a cluster-based density-functional theory (DFT) calculation augmented by a self-consistent environment, we recognize a strong electron-electron repulsion in a dimer-Mott-type ground state. On the basis of this ground state, we obtain an absorption spectrum that takes a form of a single peak in the mid-infrared (mid-IR) region. We next analyze a Hubbard model with alternate transfers, of which the values are determined by the DFT calculations. The obtained absorption peak energy is comparable to the mid-IR peak energy observed in the experiment. Finally, we also investigate other one-dimensional conductors, (TMTSF)2PF6 and (TMTTF)2PF6, which are known as correlated metals, and conclude that (EDO-TTF)2PF6 also falls in this category, in spite of its unique (0110)-type charge ordering observed in the low-temperature phase.

  5. 77 FR 6482 - Conductor Certification

    Science.gov (United States)

    2012-02-08

    ... TRANSPORTATION Federal Railroad Administration 49 CFR Part 242 Conductor Certification AGENCY: Federal Railroad..., published on November 9, 2011, which prescribed regulations for certification of conductors as required by... Certification, U.S. Department of Transportation, Federal Railroad Administration, Mail Stop-25, Room...

  6. Shubnikov de Haas oscillations in the two-dimensional organic conductor τ-(EDO-S,S-DMEDT- TTF)2(AuBr2)1+y (y˜0.75)

    Science.gov (United States)

    Konoike, Takako; Iwashita, K.; Yoshino, H.; Murata, Keizo; Sasaki, T.; Papavassiliou, G. C.

    2002-12-01

    The quasi-two-dimensional organic τ-type conductor, τ-(EDO-S,S-DMEDT-TTF)2(AuBr2)1+y (y˜0.75), shows metallic temperature dependence of the resistivity down to Tmin˜50 K, below which resistance upturn is observed. There has been no evidence of the phase transition through Tmin. In this work, in pursuit of direct evidence for metal at low temperature by transport measurement, we show an observation of the Shubnikov de Haas (SdH) oscillations for this salt. The observed frequencies of the oscillations are inconsistent with the previous band calculation. Further, it is remarkable that the amplitude of the oscillation was so giant (|Δρ/ρ0|˜30%), and the oscillation above 20 T corresponds to a N=2 Landau state, i.e., next to a quantum limit. We also observed the SdH oscillations in other τ-type conductor, τ-(P-S,S-DMEDT-TTF)2(AuBr2)1+y (y˜0.75), which almost reproduced the previous report by Storr et al. [Phys. Rev. B 64, 045107 (2001)].

  7. Understanding core conductor fabrics

    Energy Technology Data Exchange (ETDEWEB)

    Swenson, D E, E-mail: deswenson@affinity-esd.com [Affinity Static Control Consulting, LLC 2609 Quanah Drive, Round Rock, Texas, 78681 (United States)

    2011-06-23

    ESD Association standard test method ANSI/ESD STM2.1 - Garments (STM2.1), provides electrical resistance test procedures that are applicable for materials and garments that have surface conductive or surface dissipative properties. As has been reported in other papers over the past several years{sup 1} fabrics are now used in many industries for electrostatic control purposes that do not have surface conductive properties and therefore cannot be evaluated using the procedures in STM2.1{sup 2}. A study was conducted to compare surface conductive fabrics with samples of core conductor fibre based fabrics in order to determine differences and similarities with regards to various electrostatic properties. This work will be used to establish a new work item proposal within WG-2, Garments, in the ESD Association Standards Committee in the USA.

  8. Spin splitting at the high-magnetic-field phase transition of the organic conductor α-(BEDT-TTF)2KHg(SCN)4

    Science.gov (United States)

    Sasaki, Takahiko; Fukase, Tetsuo

    1999-06-01

    Spin splitting of the de Haas-van Alphen (dHvA) effect is studied in the quasi-two-dimensional organic conductor α-(BEDT-TTF)2KHg(SCN)4 by means of the magnetic torque method. The magnetic field direction dependence of the dHvA oscillation amplitude shows that the spin-splitting zero angles change at 23 T, where the phase transition magnetic field between the low-temperature, low-magnetic-field phase [antiferromagnetic (AF) phase] and the high-magnetic-field phase (M* phase) is. This change implies the increase of the g(mc/m0) value in the AF phase, where g is the g value, mc and m0 the cyclotron effective and free electron masses, respectively. The enhancement of the electron-electron interaction may be the origin of the large g(mc/m0) value in the AF phase. This result supports a model which requires a modification of the Lifshitz-Kosevich formulation in the AF phase in order to evaluate the effective mass and Dingle temperature correctly. In addition, anomalous structures on the magnetic torque curves are observed in both the AF and the M* phases. Each structure may correspond to the subsequent phase transitions by changing the magnetic field direction.

  9. Correlation Effects on Charge Order and Zero-Gap State in the Organic Conductor α-(BEDT-TTF)2I3

    Science.gov (United States)

    Tanaka, Yasuhiro; Ogata, Masao

    2016-10-01

    The effects of electron correlation in the quasi-two-dimensional organic conductor α-(BEDT-TTF)2I3 are investigated theoretically by using an extended Hubbard model with on-site and nearest-neighbor Coulomb interactions. A variational Monte Carlo method is applied to study its ground-state properties. We show that there appears a nonmagnetic horizontal-stripe charge order in which nearest-neighbor correlation functions indicate a tendency toward a spin-singlet formation on the bonds with large transfer integrals along the charge-rich stripe. Under uniaxial pressure, a first-order transition from the nonmagnetic charge order to a zero-gap state occurs. Our results on a spin correlation length in the charge-ordered state suggest that a spin gap is almost unaffected by the uniaxial pressure in spite of the suppression of the charge disproportionation. The relevance of these contrasting behaviors in spin and charge degrees of freedom to recent experimental observations is discussed.

  10. Flat conductor cable commercialization project

    Science.gov (United States)

    Hogarth, P.; Wadsworth, E.

    1977-01-01

    An undercarpet flat conductor cable and a baseboard flat conductor cable system were studied for commercialization. The undercarpet system is designed for use in office and commercial buildings. It employs a flat power cable, protected by a grounded metal shield, that terminates in receptacles mounted on the floor. It is designed to interface with a flat conductor cable telephone system. The baseboard system consists of a flat power cable mounted in a plastic raceway; both the raceway and the receptacles are mounted on the surface of the baseboard. It is designed primarily for use in residential buildings, particularly for renovation and concrete and masonry construction.

  11. 33 CFR 183.425 - Conductors: General.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Conductors: General. 183.425... Conductors: General. (a) Each conductor must be insulated, stranded copper. (b) Except for intermittent surges each conductor must not carry a current greater than that specified in Table 5 for the...

  12. 30 CFR 56.12004 - Electrical conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electrical conductors. 56.12004 Section 56....12004 Electrical conductors. Electrical conductors shall be of a sufficient size and current-carrying... insulating materials. Electrical conductors exposed to mechanical damage shall be protected....

  13. 30 CFR 57.12004 - Electrical conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electrical conductors. 57.12004 Section 57... Surface and Underground § 57.12004 Electrical conductors. Electrical conductors shall be of a sufficient... operations will not damage the insulating materials. Electrical conductors exposed to mechanical damage...

  14. 33 CFR 183.445 - Conductors: Protection.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Conductors: Protection. 183.445 Section 183.445 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Conductors: Protection. (a) Each conductor or group of conductors that passes through a bulkhead,...

  15. Electromagnetism of rotating conductors revisited

    Energy Technology Data Exchange (ETDEWEB)

    Redzic, Dragan V. [Faculty of Physics, University of Belgrade, Belgrade (Yugoslavia)]. E-mail: redzic@ff.bg.ac.yu

    2002-03-01

    The charge distribution and electromagnetic fields in a rotating, charged conductor under stationary conditions are investigated, assuming that the electrons are at rest relative to the conductor. The basic equations are found, referred to the inertial rest frame of the rotational axis, in the relativistic case, and applied to the case of a cylindrical conductor. The results obtained are compared with those of Groen and Voeyenli (Groen Oe and Voeyenli K 1982 Eur. J. Phys. 3 210-4) who considered the same problem but without taking into account the relative permittivity of the rotating conductor. It is found that the E- and B-fields do not depend on {epsilon}{sub r} and coincide with those calculated by Groen and Voeyenli; the space and surface charge densities, however, depend on {epsilon}{sub r}. (author)

  16. Graphene, a promising transparent conductor

    National Research Council Canada - National Science Library

    Wassei, Jonathan K; Kaner, Richard B

    2010-01-01

    New electronic devices such as touch screens, flexible displays, printable electronics, solid-state lighting and thin film photovoltaics have led to a rapidly growing market for flexible transparent conductors...

  17. Magnetism and Pressure-Induced Superconductivity of Checkerboard-Type Charge-Ordered Molecular Conductor β-(meso-DMBEDT-TTF2X (X = PF6 and AsF6

    Directory of Open Access Journals (Sweden)

    Yutaka Nishio

    2012-11-01

    Full Text Available The metallic state of the molecular conductor β-(meso-DMBEDT-TTF2X (DMBEDT-TTF = 2-(5,6-dihydro-1,3-dithiolo[4,5-b][1,4]dithiin-2-ylidene-5,6-dihydro-5,6-dimethyl-1,3-dithiolo[4,5-b][1,4]dithiin, X = PF6, AsF6 is transformed into the checkerboard-type charge-ordered state at around 75–80 K with accompanying metal-insulator (MI transition on the anisotropic triangular lattice. With lowering temperatures, the magnetic susceptibility decreases gradually and reveals a sudden drop at the MI transition. By applying pressure, the charge-ordered state is suppressed and superconductivity appears in β-(meso-DMBEDT-TTF2AsF6 as well as in the reported β-(meso-DMBEDT-TTF2PF6. The charge-ordered spin-gapped state and the pressure-induced superconducting state are discussed through the paired-electron crystal (PEC model, where the spin-bonded electron pairs stay and become mobile in the crystal, namely the valence-bond solid (VBS and the resonant valence bonded (RVB state in the quarter-filled band structure.

  18. A lithium superionic conductor.

    Science.gov (United States)

    Kamaya, Noriaki; Homma, Kenji; Yamakawa, Yuichiro; Hirayama, Masaaki; Kanno, Ryoji; Yonemura, Masao; Kamiyama, Takashi; Kato, Yuki; Hama, Shigenori; Kawamoto, Koji; Mitsui, Akio

    2011-07-31

    Batteries are a key technology in modern society. They are used to power electric and hybrid electric vehicles and to store wind and solar energy in smart grids. Electrochemical devices with high energy and power densities can currently be powered only by batteries with organic liquid electrolytes. However, such batteries require relatively stringent safety precautions, making large-scale systems very complicated and expensive. The application of solid electrolytes is currently limited because they attain practically useful conductivities (10(-2) S cm(-1)) only at 50-80 °C, which is one order of magnitude lower than those of organic liquid electrolytes. Here, we report a lithium superionic conductor, Li(10)GeP(2)S(12) that has a new three-dimensional framework structure. It exhibits an extremely high lithium ionic conductivity of 12 mS cm(-1) at room temperature. This represents the highest conductivity achieved in a solid electrolyte, exceeding even those of liquid organic electrolytes. This new solid-state battery electrolyte has many advantages in terms of device fabrication (facile shaping, patterning and integration), stability (non-volatile), safety (non-explosive) and excellent electrochemical properties (high conductivity and wide potential window).

  19. Focus on Organic Conductors

    OpenAIRE

    Shinya Uji, Takehiko Mori and Toshihiro Takahashi

    2009-01-01

    Organic materials are usually thought of as electrical insulators. Progress in chemical synthesis, however, has brought us a rich variety of conducting organic materials, which can be classified into conducting polymers and molecular crystals. Researchers can realize highly conducting molecular crystals in charge-transfer complexes, where suitable combinations of organic electron donor or acceptor molecules with counter ions or other organic molecules provide charge carriers. By means of a ki...

  20. Quartz antenna with hollow conductor

    Science.gov (United States)

    Leung, Ka-Ngo; Benabou, Elie

    2002-01-01

    A radio frequency (RF) antenna for plasma ion sources is formed of a hollow metal conductor tube disposed within a glass tube. The hollow metal tubular conductor has an internal flow channel so that there will be no coolant leakage if the outer glass tube of the antenna breaks. A portion of the RF antenna is formed into a coil; the antenna is used for inductively coupling RF power to a plasma in an ion source chamber. The antenna is made by first inserting the metal tube inside the glass tube, and then forming the glass/metal composite tube into the desired coil shape.

  1. Graphene, a promising transparent conductor

    Directory of Open Access Journals (Sweden)

    Jonathan K. Wassei

    2010-03-01

    Full Text Available New electronic devices such as touch screens, flexible displays, printable electronics, solid-state lighting and thin film photovoltaics have led to a rapidly growing market for flexible transparent conductors. Standard indium tin oxide films are unlikely to satisfy future needs due to losses in conductivity on bending and the escalating cost of indium which is in limited supply. Recent advances in the synthesis and characterization of graphene indicate that it may be suitable for many electronic applications including as a transparent conductor. Graphene hybrids with, for example, carbon nanotubes, may prove to be especially interesting.

  2. Improving YBCO Coated Conductors for Applications (Postprint)

    Science.gov (United States)

    2012-02-01

    AFRL-RZ-WP-TP-2012-0123 IMPROVING YBCO COATED CONDUCTORS FOR APPLICATIONS (POSTPRINT) P.N. Barnes, B.C. Harrison, J.W. Kell, and G.A...SUBTITLE IMPROVING YBCO COATED CONDUCTORS FOR APPLICATIONS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...are lighter in weight and smaller in size than their conventional counterparts. The YBCO coated conductor is expected to be the premiere HTS conductor

  3. 46 CFR 111.15-20 - Conductors.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Conductors. 111.15-20 Section 111.15-20 Shipping COAST... REQUIREMENTS Storage Batteries and Battery Chargers: Construction and Installation § 111.15-20 Conductors. (a) Each conductor penetration to a battery room must be made watertight. (b) The termination of each...

  4. 33 CFR 159.73 - Conductors.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Conductors. 159.73 Section 159.73 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.73 Conductors. Current carrying conductors must...

  5. 75 FR 69165 - Conductor Certification

    Science.gov (United States)

    2010-11-10

    ... From the Federal Register Online via the Government Publishing Office ] Part II Department of Transportation Federal Railroad Administration 49 CFR Part 242 Conductor Certification; Proposed Rule #0;#0;Federal Register / Vol. 75, No. 217 / Wednesday, November 10, 2010 / Proposed Rules#0;#0; ] DEPARTMENT...

  6. Temperature limited heater utilizing non-ferromagnetic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar,; Harold J. (Bellaire, TX), Harris; Kelvin, Christopher [Houston, TX

    2012-07-17

    A heater is described. The heater includes a ferromagnetic conductor and an electrical conductor electrically coupled to the ferromagnetic conductor. The ferromagnetic conductor is positioned relative to the electrical conductor such that an electromagnetic field produced by time-varying current flow in the ferromagnetic conductor confines a majority of the flow of the electrical current to the electrical conductor at temperatures below or near a selected temperature.

  7. Method for making conductors for ferrite memory arrays. [from pre-formed metal conductors

    Science.gov (United States)

    Heckler, C. H.; Baba, P. D.; Bhiwandker, N. C. (Inventor)

    1974-01-01

    The ferrite memory arrays are made from pre-formed metal conductors for the ferrite arrays. The conductors are made by forming a thin sheet of a metallizing paste of metal alloy powder, drying the paste layer, bisque firing the dried sheet at a first temperature, and then punching the conductors from the fired sheet. During the bisque firing, the conductor sheet shrinks to 58 percent of its pre-fired volume and the alloy particles sinter together. The conductors are embedded in ferrite sheet material and finally fired at a second higher temperature during which firing the conductors shrink approximately the same degree as the ferrite material.

  8. Composite conductor containing superconductive wires

    Energy Technology Data Exchange (ETDEWEB)

    Larson, W.L.; Wong, J.

    1974-03-26

    A superconductor cable substitute made by coworking multiple rods of superconductive niobium--titanium or niobium--zirconium alloy with a common copper matrix to extend the copper and rods to form a final elongated product which has superconductive wires distributed in a reduced cross-section copper conductor with a complete metallurgical bond between the normal-conductive copper and the superconductor wires contained therein is described. The superconductor cable can be in the form of a tube.

  9. 46 CFR 111.05-31 - Grounding conductors for systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Grounding conductors for systems. 111.05-31 Section 111... Grounding conductors for systems. (a) A conductor for grounding a direct-current system must be the larger of: (1) The largest conductor supplying the system; or (2) No. 8 AWG (8.4mm2). (b) A conductor...

  10. Determination of the Fermi velocity by angle-dependent periodic orbit resonance measurements in the organic conductor α-(BEDT-TTF)2KHg(SCN)4

    Science.gov (United States)

    Kovalev, A. E.; Hill, S.; Qualls, J. S.

    2002-10-01

    We report on detailed angle-dependent studies of the microwave (ν=50-90 GHz) interlayer magnetoelectrodynamics of a single crystal sample of the organic charge-density-wave (CDW) conductor α-(BEDT-TTF)2KHg(SCN)4. Recently developed instrumentation enables both magnetic-field (B) sweeps for a fixed sample orientation and angle sweeps at fixed ν/B. We observe series' of resonant absorptions, which we attribute to periodic orbit resonances (POR)-a phenomenon closely related to cyclotron resonance. The angle dependence of the POR indicates that they are associated with the low-temperature quasi-one-dimensional (Q1D) Fermi surface (FS) of the title compound; indeed, all of the resonance peaks collapse onto a single set of ν/B versus angle curves, generated using a semiclassical magnetotransport theory for a single Q1D FS. We show that Q1D POR measurements provide one of the most direct methods for determining the Fermi velocity, without any detailed assumptions concerning the band structure; our analysis yields an average value of vF=6.5×104 m/s. Quantitative analysis of the POR harmonic content indicates that the Q1D FS is strongly corrugated. This is consistent with the assumption that the low-temperature FS derives from a reconstruction of the high-temperature quasi-two-dimensional FS, caused by the CDW instability. Detailed analysis of the angle dependence of the POR yields parameters associated with the CDW superstructure, which are consistent with published results. Finally, we address the issue as to whether or not the interlayer electrodynamics are coherent in the title compound. We obtain a relaxation time from the POR linewidths, which is considerably longer than the interlayer hopping time, indicating that the transport in this direction is coherent.

  11. Effect of Conductor Verbalization, Dynamic Markings, Conductor Gesture, and Choir Dynamic Level on Singers' Dynamic Responses.

    Science.gov (United States)

    Skadsem, Julie A.

    1997-01-01

    Examines the effects of conductor verbalization, dynamic markings, conductor gesture, and choir dynamic level on individual singers' dynamic responses. Indicates that verbal instructions from the conductor elicited significantly stronger dynamic performance responses than did the other instructional conditions. Suggests that additional research…

  12. Responsabilidad penal del conductor ebrio

    OpenAIRE

    Gamboa Mosquera, Mauricio

    2012-01-01

    Mediante el presente artículo se busca mostrar cómo la Corte Suprema de Justicia, en aplicación de la teoría citada ut supra: determinación optativa o alternativa , ha debido aplicar por favorabilidad la condena del conductor a título de homicidio culposo, como quiera que con los mismos elementos de juicio utilizados para concluir que se actuó con dolo eventual, se ha podido arribar al delito imprudente, esto es, al comportamiento culposo.

  13. Guo Shuang, A Woman Conductor

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    BORN in a musical family in Beijing, Guo Shuang began to show her talent for music when she was nine years old and began to learn piano from her mother. At the primary and then the secondary school attached to the Central Conservatory of Music, Guo Shuang studied piano, musical theory and composing. Later, she enrolled in the Conservatory to study conducting and piano under the famous conductors Zheng Xiaoying and Xu Xin, piano professors Wu Ying and Xie Huazhen. In 1989, she went to Germany

  14. Quasi Two-Dimensional Dye-Sensitized In2O3 Phototransistors for Ultrahigh Responsivity and Photosensitivity Photodetector Applications.

    Science.gov (United States)

    Mottram, Alexander D; Lin, Yen-Hung; Pattanasattayavong, Pichaya; Zhao, Kui; Amassian, Aram; Anthopoulos, Thomas D

    2016-02-01

    We report the development of dye-sensitized thin-film phototransistors consisting of an ultrathin layer (92% in the wavelength range 400-700 nm. Importantly, the phototransistors are processed from solution-phase at temperatures below 200 °C hence making the technology compatible with inexpensive and temperature sensitive flexible substrate materials such as plastic.

  15. Magnetic phases of the quasi-two-dimensional antiferromagnet CuCrO2 on a triangular lattice

    Science.gov (United States)

    Sakhratov, Yu. A.; Svistov, L. E.; Kuhns, P. L.; Zhou, H. D.; Reyes, A. P.

    2016-09-01

    We have carried out Cu,6563 NMR spectra measurements in a magnetic field up to about 45 T on a single crystal of a multiferroic triangular antiferromagnet CuCrO2. The measurements were performed for magnetic fields aligned along the crystal c axis. Field and temperature evolution of the spectral shape demonstrates a number of phase transitions. It was found that the 3D magnetic ordering takes place in the low field range (H ≲15 T). At higher fields magnetic structures form within individual triangular planes whereas the spin directions of the magnetic ions from neighboring planes are not correlated. It is established that the 2D-3D transition is hysteretic in field and temperature. Line-shape analysis reveals several possible magnetic structures existing within individual planes for different phases of CuCrO2. Within certain regions on the magnetic H -T phase diagram of CuCrO2 a 3D magnetic ordering with tensor order parameter is expected.

  16. Quasi Two-Dimensional Dye-Sensitized In 2 O 3 Phototransistors for Ultrahigh Responsivity and Photosensitivity Photodetector Applications

    KAUST Repository

    Mottram, Alexander D.

    2016-02-10

    © 2016 American Chemical Society. We report the development of dye-sensitized thin-film phototransistors consisting of an ultrathin layer (<10 nm) of indium oxide (In2O3) the surface of which is functionalized with a self-assembled monolayer of the light absorbing organic dye D102. The resulting transistors exhibit a preferential color photoresponse centered in the wavelength region of ∼500 nm with a maximum photosensitivity of ∼106 and a responsivity value of up to 2 × 103 A/W. The high photoresponse is attributed to internal signal gain and more precisely to charge carriers generated upon photoexcitation of the D102 dye which lead to the generation of free electrons in the semiconducting layer and to the high photoresponse measured. Due to the small amount of absorption of visible photons, the hybrid In2O3/D102 bilayer channel appears transparent with an average optical transmission of >92% in the wavelength range 400-700 nm. Importantly, the phototransistors are processed from solution-phase at temperatures below 200 °C hence making the technology compatible with inexpensive and temperature sensitive flexible substrate materials such as plastic.

  17. Numerical Simulation for Two-Phase Water Hammer Flows in Pipe by Quasi-Two-Dimensional Model

    Institute of Scientific and Technical Information of China (English)

    Tae Uk Jang; Yuebin Wu; Ying Xu; Qiang Sun

    2016-01-01

    The features of a quasi⁃two⁃dimensional ( quasi⁃2D) model for simulating two⁃phase water hammer flows with vaporous cavity in a pipe are investigated. The quasi⁃2D model with discrete vaporous cavity in the pipe is proposed in this paper. This model uses the quasi⁃2D model for pure liquid zone and one⁃dimensional ( 1D ) discrete vapor cavity model for vaporous cavity zone. The quasi⁃2D model solves two⁃dimensional equations for both axial and radial velocities and 1D equations for both pressure head and discharge by the method of characteristics. The 1D discrete vapor cavity model is used to simulate the vaporous cavity occurred when the pressure in the local pipe is lower than the vapor pressure of the liquid. The proposed model is used to simulate two⁃phase water flows caused by the rapid downstream valve closure in a reservoir⁃pipe⁃valve system. The results obtained by the proposed model are compared with those by the corresponding 1D model and the experimental ones provided by the literature, respectively. The comparison shows that the maximum pressure heads simulated by the proposed model are more accurate than those by the corresponding 1D model.

  18. De Haas-van Alphen Oscillations In Quasi-two-dimensional Underdoped Cuprate Superconductors In The Canonical Ensemble

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, N [Los Alamos National Laboratory; Sebastian, S E [CAMBRIDGE UNIV.

    2008-01-01

    We calculate the de Haas-van Alphen (dHvA) effect waveform using the canonical ensemble for different Fermi surface scenarios applicable to the underdoped cuprate superconductor YBa{sub 2}Cu{sub 3}O{sub 6.5}, in which quantum oscillations have recently been observed. The harmonic content of the dHvA waveform of the principal F{sub {alpha}} {approx} 500 T frequency is consistent with the existence of a second thermodynamically dominant section of Fermi surface that acts primarily as a charge reservoir. Oscillations in the charge density to and from this reservoir are shown to potentially contribute to the observed large quantum oscillations in the Hall resistance.

  19. Mapping the directional emission of quasi-two-dimensional photonic crystals of semiconductor nanowires using Fourier microscopy

    NARCIS (Netherlands)

    Fontana, Y.; Grzela, G.; Bakkers, E.P.A.M.; Gomez Rivas, J.

    2012-01-01

    Controlling the dispersion and directionality of the emission of nanosources is one of the major goals of nanophotonics research. This control will allow the development of highly efficient nanosources even at the single-photon level. One of the ways to achieve this goal is to couple the emission to

  20. The magnetic properties of a quasi-two-dimensional spin 1 easy axis Heisenberg antiferromagnet with competing interactions

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Griffith Mendonça A., E-mail: griffith_mas@hotmail.com; Pires, A.S.T.

    2014-03-15

    The Neel and collinear ordered phases of the two-dimensional S=1 antiferromagnet with next and next near neighbor exchange interactions and easy axis single ion anisotropy, on the square lattice, are studied at low temperature using a Modified Spin Wave Theory. We calculate the low-temperature quantities as a function of the temperature, frustration and anisotropy. We calculate also the phase diagram at T=0. We found a disordered phase separating the Neel and collinear phases. - Highlights: • The phase diagrams in zero temperature. • The critical temperature was studied as a function of frustration and D. • The sublattice magnetizations and the gap were studied.

  1. Slow Oscillations of In-plane Magnetoresistance in Strongly Anisotropic Quasi-Two-Dimensional Rare-Earth Tritellurides

    Science.gov (United States)

    Sinchenko, A. A.; Grigoriev, P. D.; Monceau, P.; Lejay, P.; Zverev, V. N.

    2016-12-01

    The slow oscillations of intralayer magnetoresistance in the quasi-2D metallic compounds TbTe_3 and GdTe_3 have been observed for the first time. These oscillations do not originate from small Fermi-surface pockets, as revealed usually by Shubnikov-de Haas oscillations, but from the entanglement of close frequencies due to a finite interlayer transfer integral t_z, either between the two Te planes forming a bilayer or between two adjacent bilayers, which allows to estimate its values. For TbTe_3 and GdTe_3, we obtain the estimate t_ z≈ 1 meV.

  2. Divergence of the Long Wavelength Collective Diffusion Coefficient in Quasi-one and Quasi-two Dimensional Colloid Suspensions

    Science.gov (United States)

    Lin, Binhua; Cui, Bianxiao; Xu, Xinliang; Zangi, Ronen; Diamant, Haim; Rice, Stuart A.

    2015-03-01

    We report the results of experimental studies of the short time-long wavelength behavior of collective particle displacements in q1D and q2D colloid suspensions. Our results are reported via the q->0 behavior of the hydrodynamic function H (q) that relates the effective collective diffusion coefficient, De (q) , with the static structure factor S (q) and the self-diffusion coefficient of isolated particles Do: H (q) De (q) S (q) /Do. We find an apparent divergence of H (q) as q->0 with the form H(q)q-(1.7 qualitatively different from that of the three-dimensional H (q) and De (q) as q->0, and the divergence is of a different functional form from that predicted for the diffusion coefficient in one component 1D and 2D fluids not subject to boundary conditions that define the dimensionality of the system. The research was supported by the NSF MRSEC at the U of Chicago (NSF/DMR-MRSEC 0820054), NSF/CHE 0822838 (ChemMatCARS), and Israel Science Foundation (Grant No. 8/10).

  3. Quasi-two-dimensional electronic properties of the sodium molybdenum bronze, Na 0.9Mo 6O 17

    Science.gov (United States)

    Greenblatt, M.; Ramanujachary, K. V.; McCarroll, W. H.; Neifeld, R.; Waszczak, J. V.

    1985-09-01

    Four probe electrical resistivity measurements between 1.5 and 300 K were made on single crystals of the violet-red bronze Na 0.9Mo 6O 17 grown by a temperature gradient flux technique. The temperature variation of the resistivity shows metallic conductivity and highly anisotropic behavior similar to K 0.9Mo 6O 17 and Li 0.9Mo 6O 17. The room-temperature resistivity, measured in the direction parallel to the plate axis, is 3.0 × 10 -3 Ω cm and perpendicular to that axis it is 0.21 Ω cm. A transition observed at ˜88 K is possibly related to the onset of a charge density wave. The temperature variation of the susceptibility show Pauli paramagnetic behavior at high temperature, and highly anomalous behavior in the vicinity of the transition at low temperatures.

  4. Quasi two-dimensional electronic properties of the lithium molybdenum bronze, Li 0.9Mo 6O 17

    Science.gov (United States)

    Greenblatt, M.; McCarroll, W. H.; Neifeld, R.; Croft, M.; Waszczak, J. V.

    1984-09-01

    Four probe electrical resistivity measurements between 0.3K and 300K were made on single crystals of the violet-red bronze Li 0.9Mo 6O 17 grown by a temperature gradient flux technique. The temperature variation of the resistivity shows metallic conductivity and highly anisotropic behavior similar to K 0.9Mo 6O 17. The room temperature resistivity, measured in the direction parallel to the plate axis, is 9.5×10 -3Ωcm and 2.47Ωcm perpendicular to that axis. A phase transition observed at ˜24K is possibly related to the onset of a charge density wave. A transition to the superconducting state is observed at Tc ˜ 1.9K.

  5. Transient terahertz spectroscopy of excitons and unbound carriers in quasi two-dimensional electron-hole gases

    Energy Technology Data Exchange (ETDEWEB)

    Kaindl, Robert A.; Hagele, D.; Carnahan, M. A.; Chemla, D. S.

    2008-09-11

    We report a comprehensive experimental study and detailed model analysis of the terahertz (THz) dielectric response and density kinetics of excitons and unbound electron-hole pairs in GaAs quantum wells. A compact expression is given, in absolute units, for the complex-valued THz dielectric function of intra-excitonic transitions between the 1s and higher-energy exciton and continuum levels. It closely describes the THz spectra of resonantly generated excitons. Exciton ionization and formation are further explored, where the THz response exhibits both intra-excitonic and Drude features. Utilizing a two-component dielectric function, we derive the underlying exciton and unbound pair densities. In the ionized state, excellent agreement is found with the Saha thermodynamic equilibrium, which provides experimental verification of the two-component analysis and density scaling. During exciton formation, in turn, the pair kinetics is quantitatively described by a Saha equilibrium that follows the carrier cooling dynamics. The THz-derived kinetics is, moreover, consistent with time-resolved luminescence measured for comparison. Our study establishes a basis for tracking pair densities via transient THz spectroscopy of photoexcited quasi-2D electron-hole gases.

  6. Exponential suppression of interlayer conductivity in very anisotropic quasi-two-dimensional compounds in high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Grigoriev, P.D., E-mail: grigorev@itp.ac.ru [L. D. Landau Institute for Theoretical Physics, Chernogolovka (Russian Federation)

    2012-06-01

    It is shown that in rather strong magnetic field the interlayer electron conductivity is exponentially damped by the Coulomb barrier arising from the formation of polaron around each localized electron state. The theoretical model is developed to describe this effect, and the calculation of the temperature and field dependence of interlayer magnetoresistance is performed. The results obtained agree well with the experimental data in GaAs/AlGaAs heterostructures and in strongly anisotropic organic metals. The proposed theory allows to use the experiments on interlayer magnetoresistance to investigate the electron states, localized by magnetic field and disorder.

  7. Solid-state proton conductors

    Energy Technology Data Exchange (ETDEWEB)

    Jewulski, J.R.; Osif, T.L.; Remick, R.J.

    1990-12-01

    The purpose of this program was to survey the field of solid-state proton conductors (SSPC), identify conductors that could be used to develop solid-state fuel cells suitable for use with coal derived fuel gases, and begin the experimental research required for the development of these fuel cells. This document covers the following topics: the history of developments and current status of the SSPC, including a review of proton conducting electrolyte structures, the current status of the medium temperature SSPC development, electrodes for moderate temperature (SSPC) fuel cell, basic material and measurement techniques applicable for SSPC development, modeling and optimization studies. Correlation and optimization studies, to include correlation studies on proton conduction and oxide cathode optimization for the SSPC fuel cell. Experiments with the SSPC fuel cells including the fabrication of the electrolyte disks, apparatus for conducting measurements, the strontium-cerium based electrolyte, the barium-cerium based electrolyte with solid foil electrodes, the barium-cerium based electrolyte with porous electrodes, and conduction mechanisms. 164 refs., 27 figs., 13 tabs.

  8. Solid-state proton conductors

    Energy Technology Data Exchange (ETDEWEB)

    Remick, R.J.; Jewulski, J.; Osif, T.

    1989-01-01

    Work on this project is divided into three tasks. In the first, a comprehensive literature review was performed for the purpose of collecting data on solid proton conductors. The data was then analyzed with the goal of correlating physical and chemical characteristics with protonic conductivity in order to gain a better understanding of the phenomenon. In the second task, the results of the correlation study were used to choose an electrolyte system in which to work and to aid in the formulation of new candidate proton conductors. Under the third task, a universal test stand was constructed which can measure both electronic and protonic conductivity and which can be converted to use as a solid state fuel cell test stand. Samples of doped SrCe{sub 0.95}Yb{sub 0.05}O{sub 3} have been coated with palladium electrodes and the mechanism responsible for ionic conductivity through this material is currently under study. 6 refs., 1 fig.

  9. Solid-state proton conductors

    Science.gov (United States)

    Jewulski, J. R.; Osif, T. L.; Remick, R. J.

    1990-12-01

    The purpose of this program was to survey the field of solid-state proton conductors (SSPC), identify conductors that could be used to develop solid-state fuel cells suitable for use with coal derived fuel gases, and begin the experimental research required for the development of these fuel cells. This document covers the following topics: the history of developments and current status of the SSPC, including a review of proton conducting electrolyte structures, the current status of the medium temperature SSPC development, electrodes for moderate temperature (SSPC) fuel cell, basic material and measurement techniques applicable for SSPC development, modeling, and optimization studies. Correlation and optimization studies are described which include correlation studies on proton conduction and oxide cathode optimization for the SSPC fuel cell. Experiments with the SSPC fuel cells are presented which include the fabrication of the electrolyte disks, apparatus for conducting measurements, the strontium-cerium based electrolyte, the barium-cerium based electrolyte with solid foil electrodes, the barium-cerium based electrolyte with porous electrodes, and conduction mechanisms.

  10. Assessment of sodium conductor distribution cable

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-06-01

    The study assesses the barriers and incentives for using sodium conductor distribution cable. The assessment considers environmental, safety, energy conservation, electrical performance and economic factors. Along with all of these factors considered in the assessment, the sodium distribution cable system is compared to the present day alternative - an aluminum conductor system. (TFD)

  11. Doped LZO buffer layers for laminated conductors

    Science.gov (United States)

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2010-03-23

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  12. Superconducting fluctuations in organic molecular metals enhanced by Mott criticality.

    Science.gov (United States)

    Nam, Moon-Sun; Mézière, Cécile; Batail, Patrick; Zorina, Leokadiya; Simonov, Sergey; Ardavan, Arzhang

    2013-12-02

    Unconventional superconductivity typically occurs in materials in which a small change of a parameter such as bandwidth or doping leads to antiferromagnetic or Mott insulating phases. As such competing phases are approached, the properties of the superconductor often become increasingly exotic. For example, in organic superconductors and underdoped high-T(c) cuprate superconductors a fluctuating superconducting state persists to temperatures significantly above T(c). By studying alloys of quasi-two-dimensional organic molecular metals in the κ-(BEDT-TTF)₂X family, we reveal how the Nernst effect, a sensitive probe of superconducting phase fluctuations, evolves in the regime of extreme Mott criticality. We find strong evidence that, as the phase diagram is traversed through superconductivity towards the Mott state, the temperature scale for superconducting fluctuations increases dramatically, eventually approaching the temperature at which quasiparticles become identifiable at all.

  13. History of crystalline organic conductor

    Science.gov (United States)

    Murata, Keizo

    2017-05-01

    A brief view of crystalline organic conductor is presented. Since the discovery of TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane) in the mid 1970’s, pressure has been an indispensable tool to develop the physics of this field. From the aspect of charge transfer salt, TTF-TCNQ and its family was specified with partial charge transfer, two chain one-dimensional (1D) system, charge density wave (CDW) and commensurability. On the other hand, in (TMTSF)2X family (TMTSF: tetramethyltetraselenafulvalene, X: electron acceptor such as PF6, ClO4), complete charge transfer, one chain system, spin density wave (SDW), field-induced SDW, quantum Hall effect, superconductivity were discussed. Further, together with pressure itself, cooling rate was noticed to be important for low temperature properties. Recently, coming back to TTF-TCNQ family, i.e., HMTSF-TCNQ, whether or not field-induced CDW, instead of field-induced SDW, and quantum Hall effect is present was discussed (HMTSF: hexamethylene-tetraselenafulvalene). Whether or not the Fermiology in (TMTTF)2X under pressure is similar to that of (TMTSF)2X is discussed as well. In (BEDT-TTF)2X, new aspect of macroscopic polarization of α-(BEDT-TTF)2I3 related to charge order is described. At the end, in contrast to the charge transfer salts, non-charge transfer salt, that is, single component conductor is presented as a new possible example of Dirac cone, which was deeply studied by many researchers in α-(BEDT-TTF)2I3, together with the theoretical calculation of its magnetic susceptibility (BEDT-TTF: bisethylenedithia-tetrathiafulvalene).

  14. Frequency Dependent Losses in Transmission Cable Conductors

    DEFF Research Database (Denmark)

    Olsen, Rasmus Schmidt; Holbøll, Joachim; Guðmundsdóttir, Unnur Stella

    2011-01-01

    , such as thermal conditions in and around the cable, as well as the heat generated in conductors, screens, armours etc., taking into account proximity and skin effects. The work performed and presented in this paper is concerned with an improved determination of the losses generated in the conductor, by means...... of better calculation of the AC resistance of transmission cable conductors, in particular regarding higher frequencies. In this way, also losses under harmonics can be covered. Furthermore, the model is suitable for modelling of transient attenuation in high voltage cables. The AC resistance is calculated...

  15. 33 CFR 159.71 - Electrical controls and conductors.

    Science.gov (United States)

    2010-07-01

    ... conductors. 159.71 Section 159.71 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... Electrical controls and conductors. Electrical controls and conductors must be installed in accordance with good marine practice. Wire must be copper and must be stranded. Electrical controls and conductors...

  16. 30 CFR 56.12011 - High-potential electrical conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-potential electrical conductors. 56.12011... § 56.12011 High-potential electrical conductors. High-potential electrical conductors shall be covered, insulated, or placed to prevent contact with low potential conductors....

  17. 30 CFR 57.12011 - High-potential electrical conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-potential electrical conductors. 57.12011... Electricity Surface and Underground § 57.12011 High-potential electrical conductors. High-potential electrical conductors shall be covered, insulated, or placed to prevent contact with low potential conductors....

  18. 30 CFR 57.12080 - Bare conductor guards.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Bare conductor guards. 57.12080 Section 57... Underground Only § 57.12080 Bare conductor guards. Trolley wires and bare power conductors shall be guarded at... conductors are less than 7 feet above the rail, they shall be guarded at all points where persons work...

  19. 46 CFR 111.60-4 - Minimum cable conductor size.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Minimum cable conductor size. 111.60-4 Section 111.60-4...-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-4 Minimum cable conductor size. Each cable conductor must be #18 AWG (0.82 mm2) or larger except— (a) Each power and lighting cable conductor must...

  20. An Exploratory Comparison of Novice, Intermediate, and Expert Orchestral Conductors

    Science.gov (United States)

    Bergee, Martin J.

    2005-01-01

    This study compared novice, "intermediate" (graduate student), and expert orchestral conductors. Two novice conductors, one graduate student in orchestral conducting, and one expert conductor led a university symphony orchestra in part of the first movement of Brahms's Symphony No. 2. Wired for sound, conductors attempted to verbalize their…

  1. 46 CFR 111.50-3 - Protection of conductors.

    Science.gov (United States)

    2010-10-01

    ... conductor must be protected in accordance with its current carrying capacity, except a conductor for the..., Subpart 111.30. (c) Fuses and circuitbreakers. If the allowable current-carrying capacity of the conductor... current-carrying capacity of the conductor; and (2) The effect of temperature on the operation of...

  2. Exploitation of the photochromic nitroprusside anion [ FeNO(CN){5}] 2- as counterion for constructing molecular conductors: The first radical cation salts based on BDH-TTP and the amide functionalized derivatives of EDT-TTF

    Science.gov (United States)

    Shibaeva, R.; Khasanov, S.; Zorina, L.; Simonov, S.; Shevyakova, I.; Kushch, L.; Buravov, L.; Yagubskii, E.; Baudron, S.; Mézière, C.; Batail, P.; Canadell, E.; Yamada, J.

    2004-04-01

    The radical cation salts based on BDH-TTP and the mono- and diamide functionalized derivatives of EDT-TTF with the double charged nitroprusside anion [ FeNO(CN){5}] 2- (NP): kappa -(BDH-TTP){4}[NP]C{6}H{5}NO{2} (1), kappa -(BDH-TTP){4}[NP] (2), (BDH-TTP){2}[NP] (3), α -[ EDT-TTF-CONH{2}] {4}[NP] (4), β -[ EDT-TTF-(CONH{2})2] {2}[NP]{0.5}(C{6}H{5}NO{2})0.5 (5) have been synthesized. The crystal structures and transport properties of 1 5, as well as electronic band structures of 1and 2 have been studied. Key words. organic conductors based on radical cation salts X-ray and band structure conductivity.

  3. Materiales conductores mediante funcionalización de polímeros con nanomateriales conductores

    OpenAIRE

    Gutierrez, Manuel; Llobera, Andreu; Fernández Sánchez, César; Jiménez Jorquera, Cecilia; Mendoza Gómez, Ernest

    2010-01-01

    La presente invención se refiere un material conductor que comprende un polímero funcionalizado y a un nanomaterial conductor unidos mediante enlace covalente. La invención también se refiere a un procedimiento de obtención del material conductor sin modificar las propiedades ópticas del polímero y a su uso para la fabricación de sensores o electrodos.

  4. Materiales conductores mediante funcionalización de polímeros con nanomateriales conductores

    OpenAIRE

    Gutierrez, Manuel; Llobera, Andreu; Fernández Sánchez, César; Jiménez Jorquera, Cecilia; Mendoza Gómez, Ernest

    2010-01-01

    La presente invención se refiere un material conductor que comprende un polímero funcionalizado y a un nanomaterial conductor unidos mediante enlace covalente. La invención también se refiere a un procedimiento de obtención del material conductor sin modificar las propiedades ópticas del polímero y a su uso para la fabricación de sensores o electrodos.

  5. Failure Mechanism of Reflow Conductor Roll of Electroplating Tinning Line

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The surface roughness of reflow conductor roll was checked on membrane sample. The surface morphology of conductor roll was observed by microscope, and the composition of adhered layer on conductor roll surface was analyzed by X-ray spectroscope. The results show that tin adhesion is the main reason for failure of conductor roll, and the failure of conductor roll is accelerated by wear. The measures to decrease tin adhesion and improve wear resistance were put forward.

  6. Application of protonic conductors in metallurgy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Two types of disposable EMF hydrogen sensors for measurements of solute contents of liquid metals in situ in metal-refining processes and their general principles are introduced. The way to design new electrochemical sensors and the direction to develop new protonic conductors as new electrochemical sensors are discussed. The feasibility of protonic conductors worked as hydrogen pump in non-ferrous metal refining processes is discussed as well.

  7. Analysis and application of transmission line conductors

    Science.gov (United States)

    Laney, Orin

    Skin effect is usually a concern reserved for radio frequency design and for high current conductors used in utility power distribution. Proximity effect between adjacent conductors has traditionally been a concern for the design of magnetic windings and other applications involving wire bundles. The rise in the ubiquity of high speed bit streams and other signals of very wide bandwidth has broadened the range of applicable contexts and increased the need to account for such effects. This is especially true for transmission lines used to interconnect critical signal paths in applications ranging from microelectronic devices to the signal integrity of printed circuit traces and implementation of system cabling. Optimal conductor design is obviously fundamental to transmission line performance. Researchers have paid considerable attention to the topic but the results are scattered throughout the literature. This thesis collected information on extant conductor designs, and the theoretical considerations behind each solution. A detailed analysis of current flow in a conducting half-space was included as a foundation. The conductor types discussed were solid cylindrical, rectangular, ribbonoid, bimetallic, tubular, laminated, litz, and stranded constructions. Discussions of the performance of stranded shields and conductor roughness e¤ects were included for completeness of understanding.

  8. Effects of Conductor Baton Use on Band and Choral Musicians' Perceptions of Conductor Expressivity and Clarity

    Science.gov (United States)

    Nápoles, Jessica; Silvey, Brian A.

    2017-01-01

    The purpose of this study was to examine participants' (college band and choral musicians, N = 143) perceptions of conductor clarity and expressivity after viewing band and choral directors conducting with or without a baton. One band and one choral conductor each prepared and conducted two excerpts of Guy Forbes's "O Nata Lux", a piece…

  9. Conductor fatigue-life research. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Ramey, G.E.

    1981-07-01

    This is the final report of Research Project RP 1278-1 sponsored by the Electric Power Research Institute and carried out at the Civil Engineering Department of Auburn University (Auburn, Alabama). The objective of this study was to evaluate the effects of reducing vibration amplitudes of ACSR conductors which had been minimally damaged by aeolian vibration. The aeolian vibration was simulated by mechanical means in a controlled laboratory situation and the reduction in vibration amplitudes was a simulation of the addition of amplitude limiting devices (dampers). Conductors were vibrated at high amplitudes until a predetermined number of strand breaks occurred, after which the vibration was continued at reduced amplitudes. Three different ACSB conductors were tested: 795 KCM 26/7, 795 KCM 45/7, and 397.5 KCM 26/7. These conductors were chosen to establish the effects of conductor size and stranding on the amplitude reduction tests. Two different amplitude reductions were used to establish a threshold value for a maximum reduced amplitude. Previous preliminary research by others indicated that amplitude reductions extended the working life of conductors. This research expanded the amplitude reduction values and conductor sizes and strandings tested. For each set of parameters, four duplicative tests were performed to give statistical credence to the data. The results of the investigation indicated that amplitude reductions arrested fatigue strand breakage in each case. Electric utilities can utilize the results of this EPRI project in assessing the fatigue life of minimally damaged transmisson lines and in evaluating techniques for mitigating fatigue damage.

  10. Adsorption of molecular gases on porous materials in the SAFT-VR approximation

    CERN Document Server

    Castro, M; Martinez, A; Rosu, H C; 10.1016/j.physa.2010.04.028

    2010-01-01

    A simple molecular thermodynamic approach is applied to the study of the adsorption of gases of chain molecules on solid surfaces. We use a model based on the Statistical Associating Fluid Theory for Variable Range (SAFT-VR) potentials [A. Gil-Villegas, A. Galindo, P. J. Whitehead, S. J. Mills, G. Jackson, A. N. Burgess, J. Chem. Phys. 106 (1997) 4168] that we extend by including a quasi-two-dimensional approximation to describe the adsorption properties of this type of real gases [A. Martinez, M. Castro, C. McCabe, A. Gil-Villegas, J. Chem. Phys. 126 (2007) 074707]. The model is applied to ethane, ethylene, propane, and carbon dioxide adsorbed on activated carbon and silica gel, which are porous media of significant industrial interest. We show that the adsorption isotherms obtained by means of the present SAFT-VR modeling are in fair agreement with the experimental results provided in the literature

  11. Tunable Broadband Printed Carbon Transparent Conductor

    Science.gov (United States)

    Xu, Yue; Wan, Jiayu

    Transparent conductors have been widely applied in solar cells, transparent smart skins, and sensing/imaging antennas, etc. Carbon-based transparent conductor has attracted great attention for its low cost and broad range transparency. Ion intercalation has been known to highly dope graphitic materials, thereby tuning materials' optoelectronic properties. For the first time, we successfully tune the optical transmittance of a reduced graphene oxide (RGO)/CNT network from mid-IR range to visible range by means of Li-ion intercalation/deintercalation. We also observed a simultaneous increase of the electrical conductivity with the Li-ion intercalation. This printed carbon hybrid thin film was prepared through all solution processes and was easily scalable. This study demonstrates the possibility of using ion intercalation for low cost, tunable broadband transparent conductors.

  12. Properties and applications of perovskite proton conductors

    Directory of Open Access Journals (Sweden)

    Eduardo Caetano Camilo de Souza

    2010-09-01

    Full Text Available A brief overview is given of the main types and principles of solid-state proton conductors with perovskite structure. Their properties are summarized in terms of the defect chemistry, proton transport and chemical stability. A good understanding of these subjects allows the manufacturing of compounds with the desired electrical properties, for application in renewable and sustainable energy devices. A few trends and highlights of the scientific advances are given for some classes of protonic conductors. Recent results and future prospect about these compounds are also evaluated. The high proton conductivity of barium cerate and zirconate based electrolytes lately reported in the literature has taken these compounds to a highlight position among the most studied conductor ceramic materials.

  13. Ionic polymeric conductor nanocomposites (IPCNCs) as distributed nanosensors and nanoactuators.

    Science.gov (United States)

    Shahinpoor, Mohsen

    2008-09-01

    This paper covers advances made in connection with ionic polymeric conductor nanocomposites (IPCNCs) as distributed biomimetic nanosensors, nanoactuators, nanorobots and artificial muscles. A review of the fundamental properties and characteristics of IPCNCs will be presented first. This summary will include descriptions of the basic materials' molecular structure and subsequent procedure to manufacture the basic material for chemical plating and electroactivation. Further described are chemical molecular plating technologies to make IPCNCs; nanotechnologies of manufacturing and trapping of nanoparticles; SEM, TEM, SPM and AFM characterization of IPMNCs; biomimetic sensing and actuation characterization techniques; electrical characterization; and equivalent circuit modeling of IPCNCs as electronic materials. A phenomenological model of the underlying sensing and actuation mechanisms is also presented based on linear irreversible thermodynamics with two driving forces, an electric field and a solvent pressure gradient and two fluxes, electric current density and the ionic+solvent flux.

  14. Measuring the Magnetic Force on a Current-Carrying Conductor.

    Science.gov (United States)

    Herreman, W.; Huysentruyt, R.

    1995-01-01

    Describes a fast and simple method for measuring the magnetic force acting on a current-carrying conductor using a digital balance. Discusses the influence of current intensity and wire length on the magnetic force on the conductor. (JRH)

  15. 30 CFR 56.12048 - Communication conductors on power poles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Communication conductors on power poles. 56... Electricity § 56.12048 Communication conductors on power poles. Telegraph, telephone, or signal wires shall not be installed on the same crossarm with power conductors. When carried on poles...

  16. 30 CFR 75.513-1 - Electric conductor; size.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric conductor; size. 75.513-1 Section 75.513-1 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY... Electric conductor; size. An electric conductor is not of sufficient size to have adequate...

  17. 46 CFR 120.372 - Equipment and conductor grounding.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Equipment and conductor grounding. 120.372 Section 120... INSTALLATION Power Sources and Distribution Systems § 120.372 Equipment and conductor grounding. (a) All... together to a common ground by a normally non-current carrying conductor. Metallic cases of instruments...

  18. 21 CFR 868.1920 - Esophageal stethoscope with electrical conductors.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Esophageal stethoscope with electrical conductors... stethoscope with electrical conductors. (a) Identification. An esophageal stethoscope with electrical conductors is a device that is inserted into the esophagus to listen to a patient's heart and breath...

  19. 30 CFR 57.12048 - Communication conductors on power poles.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Communication conductors on power poles. 57... MINES Electricity Surface and Underground § 57.12048 Communication conductors on power poles. Telegraph, telephone, or signal wires shall not be installed on the same crossarm with power conductors. When...

  20. 46 CFR 183.372 - Equipment and conductor grounding.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Equipment and conductor grounding. 183.372 Section 183... conductor grounding. (a) All metallic enclosures and frames of electrical equipment must be permanently... equipment must be bonded together to a common ground by a normally non-current carrying conductor....

  1. 30 CFR 77.503 - Electric conductors; capacity and insulation.

    Science.gov (United States)

    2010-07-01

    ... UNDERGROUND COAL MINES Electrical Equipment-General § 77.503 Electric conductors; capacity and insulation. Electric conductors shall be sufficient in size and have adequate current carrying capacity and be of such... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric conductors; capacity and...

  2. 30 CFR 75.513 - Electric conductor; capacity and insulation.

    Science.gov (United States)

    2010-07-01

    ... § 75.513 Electric conductor; capacity and insulation. All electric conductors shall be sufficient in size and have adequate current carrying capacity and be of such construction that a rise in temperature... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric conductor; capacity and insulation....

  3. High Temperature Protonic Conductors by Melt Growth

    Science.gov (United States)

    2006-11-21

    A.R. de Arellano-López, A. Sayir. “Microestructura y Comportamiento Plástico de Perovsquitas Conductoras Protónicas de Alta Temperatura ”. Bol. Soc...Conductores Protónicos de Alta Temperatura Crecidos por Fusión de Zona Flotante”. VII Reunión Nacional y VI Conferencia Iberoamericana (Electrocerámica

  4. High-temperature superconducting conductors and cables

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, D.E.; Maley, M.P.; Boulaevskii, L.; Willis, J.O.; Coulter, J.Y.; Ullmann, J.L.; Cho, Jin; Fleshler, S.

    1996-09-01

    This is the final report of a 3-year LDRD project at LANL. High-temperature superconductivity (HTS) promises more efficient and powerful electrical devices such as motors, generators, and power transmission cables; however this depends on developing HTS conductors that sustain high current densities J{sub c} in high magnetic fields at temperatures near liq. N2`s bp. Our early work concentrated on Cu oxides but at present, long wire and tape conductors can be best made from BSCCO compounds with high J{sub c} at low temperatures, but which are degraded severely at temperatures of interest. This problem is associated with thermally activated motion of magnetic flux lines in BSCCO. Reducing these dc losses at higher temperatures will require a high density of microscopic defects that will pin flux lines and inhibit their motion. Recently it was shown that optimum defects can be produced by small tracks formed by passage of energetic heavy ions. Such defects result when Bi is bombarded with high energy protons. The longer range of protons in matter suggests the possibility of application to tape conductors. AC losses are a major limitation in many applications of superconductivity such as power transmission. The improved pinning of flux lines reduces ac losses, but optimization also involves other factors. Measuring and characterizing these losses with respect to material parameters and conductor design is essential to successful development of ac devices.

  5. The Conductor as a Transformational Leader.

    Science.gov (United States)

    Armstrong, Susan; Armstrong, Scott

    1996-01-01

    Identifies charisma and inspirational leadership as the most important characteristics of transformational leaders. Discusses how middle and secondary school music conductors can use the transformational leadership model. Summarizes key components of this model including positive modeling, sharing vision, and empowering others. Provides relevant…

  6. EDITORIAL: Coated conductors and their applications Coated conductors and their applications

    Science.gov (United States)

    Freyhardt, Herbert C.; Lee, Dominic; Izumi, Teruo

    2010-01-01

    The attractive perspectives offered by coated conductors, known as the 2nd generation of high temperature superconductors (2G-HTS), have triggered broad and fruitful R&D efforts to make them ready for the marketplace. The anisotropic features of YBCO and its weak-link behavior require the processing of almost single crystalline thin films into flat tapes of coated conductors by basically two different methods: RABiTS—rolling-assisted biaxially textured substrates; and IBAD—ion-beam assisted deposition. Reliable processing technologies are now at hand, and critical current carrying capacities can be raised to almost 10-20% of the theoretically possible limit by optimizing current transfer through grain boundaries as well as flux pinning through control and design of the microstructural landscapes. The optimization of the in-field properties of the 2G-HTS wires, as well as the manufacturing of coated conductors with low ac losses and of assembled conductors for high current application remain active development areas. Cost reduction and more economic processing are still an issue. However, coated conductors are now beginning to penetrate the market, particularly for power and electrical applications, where savings in energy are essential and where the unique features of high temperature superconducting materials can be utilized. Major international conferences have followed up the progress in this exciting realm, and important workshops and discussion meetings have been held on this topic. Nonetheless, it was felt that a concise and up-to-date issue of Superconductor Science and Technology would be most welcome to summarize and collect the latest developments in processing and characterizing coated conductors, as well as drawing attention to the most innovative applications. The Guest Editors of this focus issue owe great thanks to those colleagues who were willing to contribute with their most recent findings to this issue on 'Coated conductors and their

  7. Superconducting homopolar motor and conductor development

    Science.gov (United States)

    Gubser, Donald U.

    1996-10-01

    The U.S. Navy has been developing superconducting homopolar motors for ship applications since 1969; a successful at-sea demonstration of the first motor, using NbTi wire for the magnet, was achieved in the early 1980s. Recently, this same motor was used as a test bed to demonstrate progress in high-critical-temperature superconducting magnet technology using bismuth-strontium- calcium-copper-oxide (BSCCO) compounds. In the fall of 1995, this motor achieved a performance of 124 kW operating at a temperature of 4.2 K and 91 kW while operating at 28 K. Future tests are scheduled using new magnets with conductors of both the 2223 and the 2212 BSCCO phases. This article describes the advantages of superconducting propulsion and recent progress in the development of BSCCO conductors for use in Navy power systems.

  8. Local noise in a diffusive conductor

    Science.gov (United States)

    Tikhonov, E. S.; Shovkun, D. V.; Ercolani, D.; Rossella, F.; Rocci, M.; Sorba, L.; Roddaro, S.; Khrapai, V. S.

    2016-07-01

    The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive for the electronic energy distributions and extends primary local measurements towards strongly non-equilibrium regimes.

  9. Films of Carbon Nanomaterials for Transparent Conductors

    Directory of Open Access Journals (Sweden)

    Jun Wei

    2013-05-01

    Full Text Available The demand for transparent conductors is expected to grow rapidly as electronic devices, such as touch screens, displays, solid state lighting and photovoltaics become ubiquitous in our lives. Doped metal oxides, especially indium tin oxide, are the commonly used materials for transparent conductors. As there are some drawbacks to this class of materials, exploration of alternative materials has been conducted. There is an interest in films of carbon nanomaterials such as, carbon nanotubes and graphene as they exhibit outstanding properties. This article reviews the synthesis and assembly of these films and their post-treatment. These processes determine the film performance and understanding of this platform will be useful for future work to improve the film performance.

  10. Local noise in a diffusive conductor

    Science.gov (United States)

    Tikhonov, E. S.; Shovkun, D. V.; Ercolani, D.; Rossella, F.; Rocci, M.; Sorba, L.; Roddaro, S.; Khrapai, V. S.

    2016-01-01

    The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive for the electronic energy distributions and extends primary local measurements towards strongly non-equilibrium regimes. PMID:27466216

  11. Local noise in a diffusive conductor.

    Science.gov (United States)

    Tikhonov, E S; Shovkun, D V; Ercolani, D; Rossella, F; Rocci, M; Sorba, L; Roddaro, S; Khrapai, V S

    2016-07-28

    The control and measurement of local non-equilibrium configurations is of utmost importance in applications on energy harvesting, thermoelectrics and heat management in nano-electronics. This challenging task can be achieved with the help of various local probes, prominent examples including superconducting or quantum dot based tunnel junctions, classical and quantum resistors, and Raman thermography. Beyond time-averaged properties, valuable information can also be gained from spontaneous fluctuations of current (noise). From these perspective, however, a fundamental constraint is set by current conservation, which makes noise a characteristic of the whole conductor, rather than some part of it. Here we demonstrate how to remove this obstacle and pick up a local noise temperature of a current biased diffusive conductor with the help of a miniature noise probe. This approach is virtually noninvasive for the electronic energy distributions and extends primary local measurements towards strongly non-equilibrium regimes.

  12. Ray class fields of conductor p

    CERN Document Server

    Stadnik, Maria

    2012-01-01

    We prove that (under the assumption of the generalized Riemann hypothesis) a totally real multiquadratic number field K has a positive density of primes p for which the ray class field of conductor p has an explicit description as the Hilbert class field H of K adjoin the real number \\zeta_p + \\zeta_p^{-1} if and only if K contains a unit of norm -1.

  13. A Review of Coated Conductor Development

    Institute of Scientific and Technical Information of China (English)

    徐永利; 时东陆

    2003-01-01

    The developments of coated conductor technology have been reviewed. It is shown that the critical current density of high-Tc wires can begreatly enhanced by using three-fold approaches: grain alignment, grain boundary doping, and optimization of the grain architecture. Major advances have been made in the last16 years mainly in three aspects: substrates, buffer layers and the YBCO layer. Cost is still the main concern for scale up, especially for the approach through vapor depositions, such as the PLD method. TFA-MOD or other CSD methods may be the trend to overcome cost and speed consideration during the scale up. However, high reliability and reproducibility will be the new focus for these techniques. Ni-alloy tapes seem to have advantages over pure Ni in terms of mechanicalstrength and oxidation resistance. Depositing a pure Ni layer on top of Ni-based alloys (such as Ni-Cr and Ni-W alloys) solves the problem of low strength ofNi and poor texture of Ni alloys. The RABiTS and IBAD are the two robust approaches for the texture generation. But the buffer materials and architectures being investigated remain unclear, though CeO2/YSZ/CeO2 and MgO are commonly used buffer layers for RABiTS and IBAD respectively. For the case where a buffer layer isunavoidable, a non-vacuum process would be suitable for low cost and scale up. However, none of the buffer layer fabrication processes through CSD has been demonstrated results good enough for long length coated conductor applications. While, a high Jc superconducting layer can be produced by TFA-MOD, which brings a bright future for coated conductors. Clearly, there are still many scientific and technological barriers to be overcome before any long length of high Jc coated conductor be produced commercially. But theoretical analyses and technological progress show the potential for the practical application of coatedconductor wires in the near future.

  14. AA, inner conductor of a magnetic horn

    CERN Multimedia

    CERN PhotoLab

    1981-01-01

    At the start-up of the AA and during its initial operation, magnetic horns focused the antiprotons emanating from the production target. These "current-sheet lenses" had a thin inner conductor (for minimum absorption of antiprotons), machined from aluminium to wall thicknesses of 0.7 or 1 mm. The half-sine pulses rose to 150 kA in 8 microsec. The angular acceptance was 50 mrad.

  15. Current-Induced Effects in Nanoscale Conductors

    OpenAIRE

    2005-01-01

    We present an overview of current-induced effects in nanoscale conductors with emphasis on their description at the atomic level. In particular, we discuss steady-state current fluctuations, current-induced forces, inelastic scattering and local heating. All of these properties are calculated in terms of single-particle wavefunctions computed using a scattering approach within the static density-functional theory of many-electron systems. Examples of current-induced effects in atomic and mole...

  16. Hall effect in organic layered conductors

    Directory of Open Access Journals (Sweden)

    R.A.Hasan

    2006-01-01

    Full Text Available The Hall effect in organic layered conductors with a multisheeted Fermi surfaces was considered. It is shown that the experimental study of Hall effect and magnetoresistance anisotropy at different orientations of current and a quantizing magnetic field relative to the layers makes it possible to determine the contribution of various charge carriers groups to the conductivity, and to find out the character of Fermi surface anisotropy in the plane of layers.

  17. Los conductores re-examinados: El transcurso del tiempo deteriora significativamente los conocimientos de los conductores

    Directory of Open Access Journals (Sweden)

    Francisco J. Martos

    2012-01-01

    Full Text Available Dos mil cinco conductores, 1204 hombres y 801 mujeres, una muestra representativa de la población española de conductores, fueron nuevamente examinados utilizando un cuestionario que reproducía fielmente un examen de conducir realizado por la Dirección General de Tráfico (DGT. Las preguntas fueron clasificadas en"“muy importantes", "importantes" y "poco importantes". El 96.5 % de los conductores, suspendió el examen. Los resultados eran tanto peores cuanto más tiempo había transcurridodesde la obtención del permiso de conducir. Esto era independiente de la importancia de las preguntas, de la mayor o menor frecuencia de conducción y afectaba por igual a hombres y mujeres. Las mujeres obtienen mejores puntuaciones en señalización mientras que los hombres son mejores en las preguntas de seguridad vial. Los resultados también demostraban que los conductores profesionales y los de mayor nivel educativo sufren un menor deterioro. Tales resultados nos llevan a considerar la relación que estos datos puedan tener en los niveles de accidentalidad y la conveniencia de establecer pautas para la actualización del conocimiento de los conductores. Finalmente, se discute la relevancia que el examen que se utiliza para obtener el permiso de conducir tiene como indicador o predictor de una futura conducción segura.

  18. Testing of the 3M Company Composite Conductor

    Energy Technology Data Exchange (ETDEWEB)

    Stovall, John P [ORNL; Rizy, D Tom [ORNL; Kisner, Roger A [ORNL

    2010-10-01

    The 3M Company has developed a high-temperature low-sag conductor referred to as Aluminum-Conductor Composite-Reinforced or ACCR. The conductor uses an aluminum metal matrix material to replace the steel in conventional conductors. The objective of this work is to accelerate the commercial acceptance by electric utilities of this new conductor design by testing four representative conductor classes in controlled conditions. A unique facility called the Powerline Conductor Accelerated Testing (PCAT) Facility was built at ORNL for testing overhead conductors. The PCAT has been uniquely designed for testing overhead bare transmission line conductors at high currents and temperatures after they have been installed and tensioned to the manufacturer's specifications. The ability to operate a transmission line conductor in this manner does not exist elsewhere in the United States. Four classes of ACCR cable designed by the 3M Company have been successfully test at ORNL small, medium, large and small/compact. Based on these and other manufacturer tests, the 3M Company has successfully introduced the ACCR into the commercial market and has completed over twenty installations for utility companies.

  19. Hydrogen bond-promoted metallic state in a purely organic single-component conductor under pressure.

    Science.gov (United States)

    Isono, Takayuki; Kamo, Hiromichi; Ueda, Akira; Takahashi, Kazuyuki; Nakao, Akiko; Kumai, Reiji; Nakao, Hironori; Kobayashi, Kensuke; Murakami, Youichi; Mori, Hatsumi

    2013-01-01

    Purely organic materials are generally insulating. Some charge-carrier generation, however, can provide them with electrical conductivity. In multi-component organic systems, carrier generation by intermolecular charge transfer has given many molecular metals. By contrast, in purely organic single-component systems, metallic states have rarely been realized although some neutral-radical semiconductors have been reported. Here we uncover a new type of purely organic single-component molecular conductor by utilizing strong hydrogen-bonding interactions between tetrathiafulvalene-based electron-donor molecules. These conductors are composed of highly symmetric molecular units constructed by the strong intra-unit hydrogen bond. Moreover, we demonstrate that, in this system, charge carriers are produced by the partial oxidation of the donor molecules and delocalized through the formation of the symmetric intra-unit hydrogen bonds. As a result, our conductors show the highest room-temperature electrical conductivity and the metallic state under the lowest physical pressure among the purely organic single-component systems, to our knowledge.

  20. 46 CFR 111.05-33 - Equipment safety grounding (bonding) conductors.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Equipment safety grounding (bonding) conductors. 111.05... § 111.05-33 Equipment safety grounding (bonding) conductors. (a) Each equipment-grounding conductor must... 110.10-1). (b) Each equipment-grounding conductor (other than a system-grounding conductor) of a...

  1. Transport AC Losses in Striated YBCO Coated Conductors (Postprint)

    Science.gov (United States)

    2012-02-01

    AFRL-RZ-WP-TP-2012-0124 TRANSPORT AC LOSSES IN STRIATED YBCO COATED CONDUCTORS (POSTPRINT) G.A. Levin and P.N. Barnes Mechanical Energy...TRANSPORT AC LOSSES IN STRIATED YBCO COATED CONDUCTORS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...2006. 14. ABSTRACT DC current-voltage characteristics and transport ac losses of striated and non-striated Y1Ba2Cu3O7-δ ( YBCO ) coated conductors

  2. Magnetically Guiding Atoms with Current-Carrying Conductors

    Institute of Scientific and Technical Information of China (English)

    刘南春; 高伟建; 印建平

    2002-01-01

    We propose a novel magnetic guide for cold neutral atoms using some current-carrying conductors. The spatial distributions of the magnetic fields from a V-shaped or U-shaped current-carrying conductor are calculated, and the relationship between the resulting magnetic field and the parameters of the current-carrying conductors is analysed in detail. The result shows that these current-carrying conductors can be used to realize a single or a controllable double magnetic guide of cold atoms in the weak-field-seeking state, and to construct various atom-optical elements, and even to realize a single-mode atomic waveguiding under certain conditions.

  3. First qualification of ITER Toroidal Field Coil conductor jacketing

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Kazuya, E-mail: hamada.kazuya@jaea.go.jp [Japan Atomic Energy Agency (Japan); Takahashi, Yoshikazu; Isono, Takaaki; Nunoya, Yoshihiko; Matsui, Kunihiro; Kawano, Katsumi; Oshikiri, Masayuki; Tsutsumi, Fumiaki; Koizumi, Norikiyo; Nakajima, Hideo; Okuno, Kiyoshi [Japan Atomic Energy Agency (Japan); Matsuda, Hidemitsu; Yano, Yoshitaka [Nippon Steel Engineering Co. Ltd (Japan); Devred, Arnauld; Bessette, Denis [ITER Organization (France)

    2011-10-15

    The Japan Atomic Energy Agency (JAEA) has the responsibility to procure 25% of the ITER Toroidal Field Coil conductors as the Japanese Domestic Agency (JADA) in the ITER project. The TF conductor is a circular shaped, cable-in-conduit conductor, composed of a cable and a stainless steel conduit (jacket). The outer diameter and maximum length of the TF conductor are 43.7 mm and 760 m, respectively. JAEA started to produce strand, cables and jacket sections and to construct a conductor manufacturing (jacketing) facility in 2008. Following preparation in December 2009 of the jacketing facility, the dummy cable, the jacket sections and fabrication procedures, such as welding, cable insertion, compaction and spooling, JAEA manufactured a 760 m long Cu dummy conductor for process qualification. Into the 760 m long Cu dummy conductor jacketing, JAEA successfully inserted the cable with a maximum force of 32 kN. The outer diameter of the cross section of the spooled conductor was 43.7 {+-} 0.15 mm, which complies with the ITER target requirement of 43.7 {+-} 0.3 mm. Following qualification of all manufacturing processes, JAEA has started to fabricate superconducting conductors for the TF coils.

  4. The Famous Conductor,VuZhu Dokyi

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    VUzhu Dokyi,now the head of the Tibetan Song and Dance Ensemble is a second-grade conductor of the state,a member of Chinese Musicians’Association,the vice-president of Tibetan Musicians’Association and a council member of the Chinese Chorus Artists’Association.In 1960 he was admitted to the Tianjin Conservatory of Music and followed Qiu Jianhua,the famous music educator,to learn violin.After graduation,he was first violin in the Tibetan Song and Dance Ensemble Orchestra.

  5. Precision gold conductors for HMCs. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Widmer, M.R.

    1994-08-01

    Ti/Pd/Au multiple code coded switch (MCCS) networks were built and compared to Cr/Au MCCS networks. The data showed no measurable difference between the two systems. Interface resistance of both types of networks was measured as a diagnostic aid to determine if hydrogen was affecting the Ti/Pd/Au MCCS networks. The data showed that although hydrogen does affect Ti/Pd/Au, the changes are not significant with respect to MCCS environments. An evaluation of several proprietary gold electroplating solutions for use in the production of Ti/Pd/Au conductors was performed. All the testing results were comparable to the current product requirements.

  6. AA, Inner Conductor of Magnetic Horn

    CERN Multimedia

    CERN PhotoLab

    1979-01-01

    Antiprotons emerging at large angles from the production target (hit by an intense 26 GeV proton beam from the PS), were focused into the acceptance of the injection line of the AA by means of a "magnetic horn" (current-sheet lens). Here we see an early protype of the horn's inner conductor, machined from solid aluminium to a thickness of less than 1 mm. The 1st version had to withstand pulses of 150 kA, 15 us long, every 2.4 s. See 8801040 for a later version.

  7. 30 CFR 56.12010 - Isolation or insulation of communication conductors.

    Science.gov (United States)

    2010-07-01

    ... conductors. 56.12010 Section 56.12010 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... MINES Electricity § 56.12010 Isolation or insulation of communication conductors. Telephone and low... energized power conductors or any other power source....

  8. Printable elastic conductors by in situ formation of silver nanoparticles from silver flakes

    Science.gov (United States)

    Matsuhisa, Naoji; Inoue, Daishi; Zalar, Peter; Jin, Hanbit; Matsuba, Yorishige; Itoh, Akira; Yokota, Tomoyuki; Hashizume, Daisuke; Someya, Takao

    2017-08-01

    Printable elastic conductors promise large-area stretchable sensor/actuator networks for healthcare, wearables and robotics. Elastomers with metal nanoparticles are one of the best approaches to achieve high performance, but large-area utilization is limited by difficulties in their processability. Here we report a printable elastic conductor containing Ag nanoparticles that are formed in situ, solely by mixing micrometre-sized Ag flakes, fluorine rubbers, and surfactant. Our printable elastic composites exhibit conductivity higher than 4,000 S cm-1 (highest value: 6,168 S cm-1) at 0% strain, and 935 S cm-1 when stretched up to 400%. Ag nanoparticle formation is influenced by the surfactant, heating processes, and elastomer molecular weight, resulting in a drastic improvement of conductivity. Fully printed sensor networks for stretchable robots are demonstrated, sensing pressure and temperature accurately, even when stretched over 250%.

  9. Testing of the 3M Company ACCR Conductor

    Energy Technology Data Exchange (ETDEWEB)

    Stovall, J.P.; RIzy, D.T.; Kisner, R.A.; Deve, H.E. (3M Comp.)

    2010-09-15

    The 3M Company has developed a high-temperature low-sag conductor referred to as Aluminum- Conductor Composite-Reinforced or ACCR. The conductor uses an aluminum metal matrix material to replace the steel in conventional conductors so the core has a lower density and higher conductivity. The objective of this work is to accelerate the commercial acceptance by electric utilities of these new conductor designs by testing four representative conductor classes in controlled conditions. Overhead transmission lines use bare aluminum conductor strands wrapped around a steel core strands to transmit electricity. The typical cable is referred to as aluminum-conductor steel-reinforced (ACSR). The outer strands are aluminum, chosen for its conductivity, low weight, and low cost. The center strand is of steel for the strength required to support the weight without stretching the aluminum due to its ductility. The power density of a transmission corridor has been directly increased by increasing the voltage level. Transmission voltages have increased from 115-kV to 765- kV over the past 80 years. In the United States, further increasing the voltage level is not feasible at this point in time, so in order to further increase the power density of a transmission corridor, conductor designs that increase the current carrying capability have been examined. One of the key limiting factors in the design of a transmission line is the conductor sag which determines the clearance of the conductor above ground or underlying structures needed for electrical safety. Increasing the current carrying capability of a conductor increases the joule heating in the conductor which increases the conductor sag. A conductor designed for high-temperature and lowsag operation requires an engineered modification of the conductor materials. To make an advanced cable, the 3M Company solution has been the development of a composite conductor consisting of Nextel ceramic fibers to replace the steel core and

  10. Maximum permissible voltage of YBCO coated conductors

    Science.gov (United States)

    Wen, J.; Lin, B.; Sheng, J.; Xu, J.; Jin, Z.; Hong, Z.; Wang, D.; Zhou, H.; Shen, X.; Shen, C.

    2014-06-01

    Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (Ic) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the Ic degradation or burnout happens. YBCO coated conductors test in the experiment are from American superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.

  11. Maximum permissible voltage of YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Wen, J.; Lin, B.; Sheng, J.; Xu, J.; Jin, Z. [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Hong, Z., E-mail: zhiyong.hong@sjtu.edu.cn [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Wang, D.; Zhou, H.; Shen, X.; Shen, C. [Qingpu Power Supply Company, State Grid Shanghai Municipal Electric Power Company, Shanghai (China)

    2014-06-15

    Highlights: • We examine three kinds of tapes’ maximum permissible voltage. • We examine the relationship between quenching duration and maximum permissible voltage. • Continuous I{sub c} degradations under repetitive quenching where tapes reaching maximum permissible voltage. • The relationship between maximum permissible voltage and resistance, temperature. - Abstract: Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (I{sub c}) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the I{sub c} degradation or burnout happens. YBCO coated conductors test in the experiment are from American superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.

  12. Novel processing of HTS based conductors

    Science.gov (United States)

    Ginley, D. S.; Venturini, E. L.; Kwak, J. F.; Baughman, R. J.; Bourcier, R. J.; Mitchell, M. A.; Morosin, B.; Halloran, J. W.; Neal, N. J.; Capone, D. W.

    1990-04-01

    Conductor development is one of the major long term goals in high temperature superconductor research. Two promising processing technologies that were utilized to produce superconducting HTS conductors are reported. First, melt spun YBa2Cu3O7 fibers rapid thermal processed for 1 to 8 sec at 950 to 1075 C have (Tc)'s to 92 K, J(sub c)'s to 1100 A/sq cm and the orthorhombic twinned morphology typical for high quality YBa2Cu3O7. A processing matrix of time, temperature and composition for these fibers shows that slightly CuO-rich starting compositions give the best results. Second, silver tube encapsulated wires of Bi(1.7)Pb(0.3)Sr2Ca2Cu3O10 were made by extrusion, wire drawing and cold rolling. The resulting tapes show orientation of the crystallites, zero resistance up to 100 K and improved magnetic hysteresis above 50 K. The combination of mechanical reprocessing and extended thermal anneals near 850 C appears to significantly improve these materials.

  13. The Identification of Conductor-Distinguished Functions of Conducting

    Science.gov (United States)

    Gumm, Alan J.; Battersby, Sharyn L.; Simon, Kathryn L.; Shankles, Andrew E.

    2011-01-01

    The purpose of the present study was to identify whether conductors distinguish functions of conducting similarly to functions implied in previous research. A sample of 84 conductors with a full range of experience levels (M = 9.8) and of a full range of large ensemble types and ensemble age levels rated how much they pay attention to 82…

  14. Elastically stretchable thin film conductors on an elastomeric substrate

    Science.gov (United States)

    Jones Harris, Joyelle Elizabeth

    Imagine a large, flat screen television that can be rolled into a small cylinder after purchase in the store and then unrolled and mounted onto the wall of a home. The electronic devices within the television must be able to withstand large deformation and tensile strain. Consider a robot that is covered with an electronic skin that simulates human skin. The skin would enable the machine to lift an elderly person with care and sensitivity. The skin will endure repeated deformation with the highest tensile strains being experienced at the robot's joints. These applications and many others will benefit from stretchable electronic circuitry. While several different methods have been employed to create stretchable electronics, all methods use a common tool -- stretchable conductors. Therefore, the goal of this thesis work was to fabricate elastically stretchable conductors that can be used in stretchable electronics. We deposited Au thin films on an elastomeric substrate, and the resulting conductors remained electrically continuous when stretched by 30% and more. We developed photolithographic processes that can be used to pattern elastically stretchable conductors with a 10 mum resolution. We fabricated bi-level stretchable conductors that are separated by an elastomeric insulator and are electrically connected through via holes in the insulator. We applied our bi-level conductors to create a stretchable resistor-inductor-capacitor (RLC) circuit with a tunable resonant frequency. We also used stretchable conductors to measure action potentials in biological samples. This thesis describes the fabrication and application of our elastically stretchable conductors.

  15. Beyond the Beat: Modelling Intentions in a Virtual Conductor

    NARCIS (Netherlands)

    Maat, ter Mark; Ebbers, Rob M.; Reidsma, Dennis; Nijholt, Anton

    2008-01-01

    We describe our research on designing and implementing a Virtual Conductor. That is, a virtual human (embodied agent) that acts like a human conductor in its interaction with a real, human orchestra. We reported previously on a first version that used a digital musical score to lead an orchestra. Th

  16. Overcurrent experiments on HTS tape and cable conductor

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Jensen, Kim Høj; Træholt, Chresten;

    2001-01-01

    their critical current. In this light, it is important to investigate the response of HTS tapes and cable conductors to overcurrents several times the critical current. A number of experiments have been performed on HTS tapes and cable conductors, with currents up to 20 times the critical current. During...... overcurrent experiments, the voltage, and the temperature were measured as functions of time in order to investigate the dynamic behavior of the HTS tape and cable conductor. After each experiment, damage to the superconductors was assessed by measuring the critical current. Preliminary results show...... that within seconds an HTS tape (critical current=17 A) heats above room temperature with an overcurrent larger than 140 A. Similar overcurrent experiments showed that a HTS cable conductor could sustain damage with overcurrents exceeding 10 times the critical current of the cable conductor....

  17. ELECTRODYNAMIC STABILITY COMPUTATIONS FOR FLEXIBLE CONDUCTORS OF THE AERIAL LINES

    Directory of Open Access Journals (Sweden)

    I. I. Sergey

    2015-01-01

    Full Text Available In aerial transmission lines aluminium multiwire conductors are in use. Owing to their flexible design the electrodynamic effect of short circuit currents may lead to intolerable mutual rendezvous and even cross-whipping of the phase conductors. The increasing motion of the conductors caused by effect of the short-circuit electrodynamic force impulse is accompanied by the dynamic load impact affecting the conductors, insulating and supporting constructions of the aerial lines. Intensity of the short-circuit currents electrodynamic impact on the flexible conductors depends on the short circuit current magnitude. For research into electrodynamic endurance of the conductors of the aerial lines located at the vertices of arbitrary triangle with spans of a large length, the authors assume the conductor analytical model in the form of a flexible tensile thread whose mass is distributed evenly lengthwise the conductor. With this analytical model, by the action of the imposed forces the conductor assumes the form conditioned by the diagram of applied external forces, and resists neither bending nor torsion. The initial conditions calculation task reduces to solving the flexible thread statics equations. The law of motion of the conductor marginal points comes out of the conjoint solution of dynamic equations of the conductor and structural components of the areal electric power lines. Based on the proposed algorithm, the researchers of the Chair of the Electric Power Stations of BNTU developed a software program LINEDYS+, which in its characteristics yields to no foreign analogs, e. g. SAMSEF. To calculate the initial conditions they modified a software program computing the flexible conductor mechanics named MR 21. The conductor short-circuit electrodynamic interaction estimation considers structural elements of the areal lines, ice and wind loads, objective parameters of the short circuit. The software programs are accommodated with the simple and

  18. Intrinsic magnetization in the novel quasi-two-dimensional superconducting and magnetic Fe1+δTe1-xSex system

    Science.gov (United States)

    Yoshimura, Kazuyoshi; Michioka, Chishiro; Matsui, Mami; Ohta, Hiroto; Yang, Jinhu; Fang, Minghu

    2011-06-01

    Intrinsic spin susceptibility of the novel layered superconducting and magnetic system Fe1+δTe1-xSex was investigated by means of the magnetization measurements in comparing with the 125Te NMR Knight shift 125K. The macroscopic uniform susceptibility in Fe1+δTe1-xSex consists of the itinerant magnetization originated in the Fe(1) site, localized one in the Fe(2) site and the ferromagnetic-like impurity which is frequently sandwiched by the thin film-like single crystals. Unlike the macroscopic magnetization, Knight shift 125K is mainly attributed to the itinerant magnetism of the Fe(1) site, which is important for the superconductivity and the magnetism in the Fe1+δTe1-xSex system. The magnetic susceptibility estimated in the high-field region agrees well with 125K. The uniform susceptibility of the superconducting Fe1+δTe1-xSex gradually decreases with decreasing temperature in the normal state accompanied by the growth of antiferromagnetic spin afluctuations.

  19. Zigzag antiferromagnetic ground state with anisotropic correlation lengths in the quasi-two-dimensional honeycomb lattice compound N a2C o2Te O6

    Science.gov (United States)

    Bera, A. K.; Yusuf, S. M.; Kumar, Amit; Ritter, C.

    2017-03-01

    The crystal structure, magnetic ground state, and the temperature-dependent microscopic spin-spin correlations of the frustrated honeycomb lattice antiferromagnet N a2C o2Te O6 have been investigated by powder neutron diffraction. A long-range antiferromagnetic (AFM) ordering has been found below TN˜24.8 K . The magnetic ground state, determined to be zigzag antiferromagnetic and characterized by a propagation vector k =(1 /2 0 0 ) , occurs due to the competing exchange interactions up to third-nearest neighbors within the honeycomb lattice. The exceptional existence of a limited magnetic correlation length along the c axis (perpendicular to the honeycomb layers in the a b planes) has been found even at 1.8 K, well below the TN˜24.8 K . The observed limited correlation along the c axis is explained by the disorder distribution of the Na ions within the intermediate layers between honeycomb planes. The reduced ordered moments mCo (1 )=2.77 (3 ) μB/C o2 + and mCo (2 )=2.45 (2 ) μB/C o2 + at 1.8 K reflect the persistence of spin fluctuations in the ordered state. Above TN˜24.8 K , the presence of short-range magnetic correlations, manifested by broad diffuse magnetic peaks in the diffraction patterns, has been found. Reverse Monte Carlo analysis of the experimental diffuse magnetic scattering data reveals that the spin correlations are mainly confined within the two-dimensional honeycomb layers (a b plane) with a correlation length of ˜12 Å at 25 K. The nature of the spin arrangements is found to be similar in both the short-range and long-range ordered magnetic states. This implies that the short-range correlation grows with decreasing temperature and leads to the zigzag AFM ordering at T ≤TN . The present study provides a comprehensive picture of the magnetic correlations over the temperature range above and below the TN and their relation to the crystal structure. The role of intermediate soft Na layers on the magnetic coupling between honeycomb planes is discussed.

  20. Coherent optical nonlinearities and phase relaxation of quasi-three-dimensional and quasi-two-dimensional excitons in ZnSxSe1 - x/ZnSe structures

    DEFF Research Database (Denmark)

    Wagner, Hans Peter; Schätz, A.; Maier, R.

    1997-01-01

    We investigate the dephasing of heavy-hole excitons in different free-standing ZnSxSe1-x/ZnSe layer structures by spectrally resolved transient four-wave mixing. ZnSe layers of 80, 8, and 4 nm thickness with ternary barriers are studied, representing the crossover from quasi-three-dimensional to ......We investigate the dephasing of heavy-hole excitons in different free-standing ZnSxSe1-x/ZnSe layer structures by spectrally resolved transient four-wave mixing. ZnSe layers of 80, 8, and 4 nm thickness with ternary barriers are studied, representing the crossover from quasi...

  1. Transport properties of a quasi-two-dimensional electron system formed in LaAlO3/EuTiO3/SrTiO3 heterostructures

    Science.gov (United States)

    De Luca, G. M.; Di Capua, R.; Di Gennaro, E.; Granozio, F. Miletto; Stornaiuolo, D.; Salluzzo, M.; Gadaleta, A.; Pallecchi, I.; Marrè, D.; Piamonteze, C.; Radovic, M.; Ristic, Z.; Rusponi, S.

    2014-06-01

    We study the structural, magnetic, and transport properties of LaAlO3/EuTiO3/SrTiO3 heterostructures grown by pulsed laser deposition. The samples are characterized in situ by electron diffraction and scanning probe microscopy and ex situ by transport measurements and x-ray absorption spectroscopy. LaAlO3/EuTiO3/SrTiO3 films show a ferromagnetic transition at T ≤7.5 K, related to the ordering of Eu2+ spins, even in samples characterized by just two EuTiO3 unit cells. A finite metallic conductivity is observed only in the case of samples composed by one or two EuTiO3 unit cells and, simultaneously, by a LaAlO3 thickness greater than or equal to four unit cells. The effect of ferromagnetic EuTiO3 on the transport properties of δ-doped LaAlO3/EuTiO3/SrTiO3 is critically discussed.

  2. Flexible Quasi-Two-Dimensional CoFe2O4 Epitaxial Thin Films for Continuous Strain Tuning of Magnetic Properties.

    Science.gov (United States)

    Zhang, Yong; Shen, Lvkang; Liu, Ming; Li, Xin; Lu, Xiaoli; Lu, Lu; Ma, Chunrui; You, Caiyin; Chen, Aiping; Huang, Chuanwei; Chen, Lang; Alexe, Marin; Jia, Chun-Lin

    2017-08-22

    Epitaxial thin films of CoFe2O4 (CFO) have successfully been transferred from a SrTiO3 substrate onto a flexible polyimide substrate. By bending the flexible polyimide, different levels of uniaxial strain are continuously introduced into the CFO epitaxial thin films. Unlike traditional epitaxial strain induced by substrates, the strain from bending will not suffer from critical thickness limitation, crystalline quality variation, and substrate clamping, and more importantly, it provides a more intrinsic and reliable way to study strain-controlled behaviors in functional oxide systems. It is found that both the saturation magnetization and coercivity of the transferred films can be changed over the bending status and show a high accord with the movement of the curvature bending radius of the polyimide substrate. This reveals that the mechanical strain plays a critical role in tuning the magnetic properties of CFO thin films parallel and perpendicular to the film plane direction.

  3. Plasma Waves and Jets from Moving Conductors

    CERN Document Server

    Gralla, Samuel E

    2016-01-01

    We consider force-free plasma waves launched by the motion of conducting material through a magnetic field. We develop a spacetime-covariant formalism for perturbations of a uniform magnetic field and show how the transverse motion of a conducting fluid acts as a source. We show that fast-mode waves are sourced by the compressibility of the fluid, with incompressible fluids launching a pure-Alfven outflow. Remarkably, this outflow can be written down in closed form, at the nonlinear level, for an arbitrary incompressible flow. The instantaneous flow velocity is imprinted on the magnetic field and transmitted away at the speed of light, carrying detailed information about the conducting source at the time of emission. These results can be applied to transients in pulsar outflows and to jets from neutron stars orbiting in the magnetosphere of another compact object. We discuss jets from moving conductors in some detail.

  4. Microwave Loss Reduction in Cryogenically Cooled Conductors

    CERN Document Server

    Finger, R

    2015-01-01

    Measurements of microwave attenuation at room temperature and 4.2 K have been performed on some conductors commonly used in receiver input circuits. The reduction in loss on cooling is substantial, particularly for copper and plated gold, both of which showed a factor of 3 loss reduction. Copper passivated with benzotriazole shows the same loss as without passivation. The residual resistivity ratio between room temperature and 4.2 K, deduced from the measurements using the classical skin effect formula, was smaller than the measured DC value to a degree consistent with conduction in the extreme anomalous skin effect regime at cryogenic temperatures. The measurements were made in the 5-10 GHz range. The materials tested were: aluminum alloys 1100-T6 and 6061-O, C101 copper, benzotriazole treated C101 copper, and brass plated with electroformed copper, Pur-A-Gold 125-Au soft gold, and BDT200 bright gold.

  5. Alternative fiber optic conductor for laboratory practices

    Science.gov (United States)

    Calderon Ocampo, Juan F.; Jaramillo Florez, Samuel A.; Amaya Rodriguez, Juan C.

    1995-10-01

    Due to the high cost and difficulty in obtaining an optical fiber sample to be used in laboratory tests, we have given ourselves the task of looking for an adequate optical-fiber alternative for laboratory practices. We have as a result, found an object that can be used as an alternate optical conductor. This object called 'Venoclisis Hose', is a cylindrical plastic tube, hollow inside, whose main use has been in medical applications as a conveyor of liquids going in or coming out of the human body. In this document, the tests carried out and the results obtained to characterize the venoclisis as an optical fiber are described. This project was undertaken in order to propose the use of Venoclisis as an alternate optical fiber for laboratory work, due primarily to its low costs, as well as how easy it to acquire and measure its parameters as an optical fiber.

  6. Conductors and Newforms for (1,1)

    Indian Academy of Sciences (India)

    Joshua Lansky; A Raghuram

    2004-11-01

    Let be a non-Archimedean local field whose residue characteristic is odd. In this paper we develop a theory of newforms for (1,1)(), building on previous work on $SL_2(F)$. This theory is analogous to the results of Casselman for $GL_2(F)$ and Jacquet, Piatetski-Shapiro, and Shalika for $GL_n(F)$. To a representation π of (1,1)(), we attach an integer () called the conductor of , which depends only on the -packet containing . A newform is a vector in which is essentially fixed by a congruence subgroup of level ()$. We show that our newforms are always test vectors for some standard Whittaker functionals, and, in doing so, we give various explicit formulae for newforms.

  7. Random matrix model for disordered conductors

    Indian Academy of Sciences (India)

    Zafar Ahmed; Sudhir R Jain

    2000-03-01

    We present a random matrix ensemble where real, positive semi-definite matrix elements, , are log-normal distributed, $\\exp[-\\log^{2}(x)]$. We show that the level density varies with energy, , as 2/(1 + ) for large , in the unitary family, consistent with the expectation for disordered conductors. The two-level correlation function is studied for the unitary family and found to be largely of the universal form despite the fact that the level density has a non-compact support. The results are based on the method of orthogonal polynomials (the Stieltjes-Wigert polynomials here). An interesting random walk problem associated with the joint probability distribution of the ensuing ensemble is discussed and its connection with level dynamics is brought out. It is further proved that Dyson's Coulomb gas analogy breaks down whenever the confining potential is given by a transcendental function for which there exist orthogonal polynomials.

  8. Frequency Dependent Losses in Transmission Cable Conductors

    DEFF Research Database (Denmark)

    Olsen, Rasmus Schmidt; Holbøll, Joachim; Guðmundsdóttir, Unnur Stella

    2011-01-01

    Denmark is taking on the exciting project of undergrounding the electricity transmission grid. In 2009 it was decided by the Danish government to underground large parts of the 400 kV and the entire 132-150 kV transmission network before the end of 2030. For ensuring network stability...... and economical gain, such severe network changes necessitate correct estimation and optimisation of load conditions in the cable grid. Both IEC and IEEE have published standards for rating transmission cables' current carrying capacity. These standards are based on assumptions of a number of parameters...... of better calculation of the AC resistance of transmission cable conductors, in particular regarding higher frequencies. In this way, also losses under harmonics can be covered. Furthermore, the model is suitable for modelling of transient attenuation in high voltage cables. The AC resistance is calculated...

  9. Conduction Mechanisms and Structure of Ionomeric Single-Ion Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Ralph H. [Pennsylvania State Univ., University Park, PA (United States); Maranas, Janna K. [Pennsylvania State Univ., University Park, PA (United States); Mueller, Karl T. [Pennsylvania State Univ., University Park, PA (United States); Runt, James [Pennsylvania State Univ., University Park, PA (United States); Winey, Karen I. [Univ. of Pennsylvania, Philadelphia, PA (United States)

    2015-03-01

    Our team has designed using DFT (Gaussian) and synthesized low glass transition temperature single-ion conductors that are either polyanions that conduct small cations Li+, Na+, Cs+ or polycations that conduct small anions F-, OH-, Br-. We utilize a wide range of complimentary experimental materials characterization tools to understand ion transport; differential scanning calorimetry, dielectric relaxation spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, linear viscoelasticity, X-ray scattering and molecular dynamics simulations. The glass transition temperature Tg needs to be as low as possible to facilitate ion transport, so the nonionic parts of the polymer need to be polar, flexible and have strong solvation interactions with the ions. The lowest Tg we have managed for polyanions conducting Li+ is -60 °C. In contrast, polysiloxanes with PEO side chains and tetrabutylphosphonium cationic side groups have Tg ≈ -75 °C that barely increases with ion content, as anticipated by DFT. A survey of all polyanions in the literature suggests that Tg < -80 °C is needed to achieve the 10-4 S/cm conductivity needed for battery separators.

  10. Dynamics of caged ions in glassy ionic conductors.

    Science.gov (United States)

    Habasaki, J; Ngai, K L; Hiwatari, Y

    2004-05-01

    At sufficiently high frequency and low temperature, the dielectric responses of glassy, crystalline, and molten ionic conductors all invariably exhibit nearly constant loss. This ubiquitous characteristic occurs in the short-time regime when the ions are still caged, indicating that it could be a determining factor of the mobility of the ions in conduction at longer times. An improved understanding of its origin should benefit the research of ion conducting materials for portable energy source as well as the resolution of the fundamental problem of the dynamics of ions. We perform molecular dynamics simulations of glassy lithium metasilicate (Li2SiO3) and find that the length scales of the caged Li+ ions motions are distributed according to a Levy distribution that has a long tail. These results suggest that the nearly constant loss originates from "dynamic anharmonicity" experienced by the moving but caged Li+ ions and provided by the surrounding matrix atoms executing correlated movements. The results pave the way for rigorous treatments of caged ion dynamics by nonlinear Hamiltonian dynamics.

  11. Conduction Mechanisms and Structure of Ionomeric Single-Ion Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Colby, Ralph H.; Maranas, Janna K; Mueller, Karl T; Runt, James; Winey, Karen I

    2015-03-05

    Our team has designed using DFT (Gaussian) and synthesized low glass transition temperature single-ion conductors that are either polyanions that conduct small cations Li, Na, Cs or polycations that conduct small anions F, OH, Br. We utilize a wide range of complimentary experimental materials charactization tools to understand ion transport; differential scanning calorimetry, dielectric relaxation spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, linear viscoelasticity, X-ray scattering and molecular dynamics simulations. The glass transition temperature Tg needs to be as low as possible to facilitate ion transport, so the nonionic parts of the polymer need to be polar, flexible and have strong solvation interactions with the ions. The lowest Tg we have managed for polyanions conducting Li is -60 C. In contrast, polysiloxanes with PEO side chains and tetrabutylphosphonium cationic side groups have Tg ~ -75C that barely increases with ion content, as anticipated by DFT. A survey of all polyanions in the literature suggests that Tg < -80C is needed to achieve the 10-4 S/cm conductivity needed for battery separators.

  12. Modelling the transient emission from a twin conductor cable

    OpenAIRE

    2016-01-01

    Using the equations of transmission line theory, a programme is developed to simulate the response of an open-circuit line to a step pulse. This is compared with the observed response of a twin-conductor cable. It is deduced that not all of the current delivered to the send conductor arrives back via the return conductor. Some of it departs in the form of radiated emission. A virtual capacitor is used to simulate this, with limited success. However, by adding a second virtual capacitor to sim...

  13. Recent progress in high-pressure studies on organic conductors

    Directory of Open Access Journals (Sweden)

    Syuma Yasuzuka and Keizo Murata

    2009-01-01

    Full Text Available Recent high-pressure studies of organic conductors and superconductors are reviewed. The discovery of the highest Tc superconductivity among organics under high pressure has triggered the further progress of the high-pressure research. Owing to this finding, various organic conductors with the strong electron correlation were investigated under high pressures. This review includes the pressure techniques using the cubic anvil apparatus, as well as high-pressure studies of the organic conductors up to 10 GPa showing extraordinary temperature and pressure dependent transport phenomena.

  14. Enhanced Mixed Electronic-Ionic Conductors through Cation Ordering

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Allan J. [Univ. of Houston, TX (United States); Morgan, Dane [Univ. of Wisconsin, Madison, WI (United States); Grey, Clare [Stony Brook Univ., NY (United States)

    2014-08-31

    The performance of many energy conversion and storage devices depend on the properties of mixed ionic-electronic conducting (miec) materials. Mixed or ambipolar conductors simultaneously transport ions and electrons and provide the critical interface between chemical and electrical energy in devices such as fuel cells, ion transport membranes, and batteries. Enhancements in storage capacity, reversibility, power density and device lifetime all require new materials and a better understanding of the fundamentals of ambipolar conductivity and surface reactivity.The high temperature properties of the ordered perovksites AA’B2O5+x, where A = rare earth ion, Y and B = Ba, Sr were studied. The work was motivated by the high oxygen transport and surface exchange rates observed for members of this class of mixed ionic and electronic conductors. A combined experimental and computational approach, including structural, electrochemical, and transport characterization and modeling was used. The approach attacks the problem simultaneously at global (e.g., neutron diffraction and impedance spectroscopy), local (e.g., pair distribution function, nuclear magnetic resonance) and molecular (ab initio thermokinetic modeling) length scales. The objectives of the work were to understand how the cation and associated anion order lead to exceptional ionic and electronic transport properties and surface reactivity in AA’B2O5+x perovskites. A variety of compounds were studied by X-ray and neutron diffraction, measurements of thermodynamics and transport and theoretically. These included PrBaCo2O5+x and NdBaCo2O5+x, PrBaCo2-xFexO6- δ (x = 0, 0.5, 1.0, 1.5 and 2) and LnBaCoFeO6- δ (Ln = La, Pr, Nd, Sm, Eu and Gd), Sr3YCo4O10.5, YBaMn2O5+x. A0.5A’0.5BO3 (where A=Y, Sc, La, Ce, Pr, Nd, Pm, Sm; A’= Sr

  15. 33 CFR 183.430 - Conductors in circuits of less than 50 volts.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Conductors in circuits of less... Requirements § 183.430 Conductors in circuits of less than 50 volts. (a) Each conductor in a circuit that has a...; resistance conductors that control circuit amperage; and pigtails of less than seven inches of exposed length....

  16. 33 CFR 183.435 - Conductors in circuits of 50 volts or more.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Conductors in circuits of 50... Requirements § 183.435 Conductors in circuits of 50 volts or more. (a) Each conductor in a circuit that has a nominal voltage of 50 volts or more must be: (1) A conductor that has insulation listed and...

  17. 30 CFR 56.12005 - Protection of power conductors from mobile equipment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protection of power conductors from mobile... MINES Electricity § 56.12005 Protection of power conductors from mobile equipment. Mobile equipment shall not run over power conductors, nor shall loads be dragged over power conductors, unless...

  18. Study on detinning process of a reflow conductor roll

    Institute of Scientific and Technical Information of China (English)

    FU Hanguang; DAI Mingshan; FU Hanfeng

    2005-01-01

    Adhering tin is the main reason of a reflow conductor roll which works in an electroplating tin line (ETL). A detinning agent whose main composition is NaOH and KOH and assistant composition is Na2PbO2 or K2PbO2 and NaNO3 or NaNO2 has excellent detinning effects when the temperature of detinning solution is 40-80℃ and the temperature of the reflow conductor roll reaches 40-70℃. After the adhering tin layer of the reflow conductor roll is removed, the roughness of the reflow conductor roll can resume to 4.0 μm, its service life increases by 80%, and the repairing cost decreases by 90%.

  19. Casimir Free Energy at High Temperatures: Grounded vs Isolated Conductors

    CERN Document Server

    Fosco, C D; Mazzitelli, F D

    2016-01-01

    We evaluate the difference between the Casimir free energies corresponding to either grounded or isolated perfect conductors, at high temperatures. We show that a general and simple expression for that difference can be given, in terms of the electrostatic capacitance matrix for the system of conductors. For the case of close conductors, we provide approximate expressions for that difference, by evaluating the capacitance matrix using the proximity force approximation. Since the high-temperature limit for the Casimir free energy for a medium described by a frequency-dependent conductivity diverging at zero frequency coincides with that of an isolated conductor, our results may shed light on the corrections to the Casimir force in the presence of real materials.

  20. High voltage switches having one or more floating conductor layers

    Energy Technology Data Exchange (ETDEWEB)

    Werne, Roger W.; Sampayan, Stephen; Harris, John Richardson

    2015-11-24

    This patent document discloses high voltage switches that include one or more electrically floating conductor layers that are isolated from one another in the dielectric medium between the top and bottom switch electrodes. The presence of the one or more electrically floating conductor layers between the top and bottom switch electrodes allow the dielectric medium between the top and bottom switch electrodes to exhibit a higher breakdown voltage than the breakdown voltage when the one or more electrically floating conductor layers are not present between the top and bottom switch electrodes. This increased breakdown voltage in the presence of one or more electrically floating conductor layers in a dielectric medium enables the switch to supply a higher voltage for various high voltage circuits and electric systems.

  1. Numerical analysis of quench in coated conductors with defects

    Science.gov (United States)

    Liu, Wenbin; Yong, Huadong; Zhou, Youhe

    2016-09-01

    When the superconductor is subjected to local thermal perturbations, a large amount of joule heat may be generated in the conductor, which may lead to a quench. In a quench event, a normal zone irreversibly spreads throughout the conductor leading to failure of the superconducting device. In this paper, we will discuss the one-dimensional quench behavior in the coated conductors with internal defects or interface defects. Based on the numerical procedure given in the previous works, the normal zone propagation is studied by using the finite difference method. The numerical results are presented to discuss the normal zone propagation. We consider the effect of internal defect on the nonuniform temperature propagation. For the conductor with interface defects, it can be found that the normal zone propagation velocity is increased by defects.

  2. Numerical analysis of quench in coated conductors with defects

    Directory of Open Access Journals (Sweden)

    Wenbin Liu

    2016-09-01

    Full Text Available When the superconductor is subjected to local thermal perturbations, a large amount of joule heat may be generated in the conductor, which may lead to a quench. In a quench event, a normal zone irreversibly spreads throughout the conductor leading to failure of the superconducting device. In this paper, we will discuss the one-dimensional quench behavior in the coated conductors with internal defects or interface defects. Based on the numerical procedure given in the previous works, the normal zone propagation is studied by using the finite difference method. The numerical results are presented to discuss the normal zone propagation. We consider the effect of internal defect on the nonuniform temperature propagation. For the conductor with interface defects, it can be found that the normal zone propagation velocity is increased by defects.

  3. A microstructure continuum approach to electromagneto-elastic conductors

    Science.gov (United States)

    Romeo, Maurizio

    2016-11-01

    A micromorphic continuum model of a deformable electromagnetic conductor is established introducing microdensities of bound and free charges. The conductive part of electric current consists of contributions due to free charges and microdeformation. Beside the conservation of charge, we derive suitable evolution equations for electric multipoles which are exploited to obtain the macroscopic form of Maxwell's equations. A constitutive model for electromagneto-elastic conductors is considered which allows for a natural characterization of perfect conductors independently on the form of the constitutive equation for the conduction current. A generalized Ohm's law is also derived for not ideal conductors which accounts for relaxation effects. The consequences of the linearized Ohm's law on the classic magnetic transport equation are shown.

  4. Electron transport in a mesoscopic superconducting ferromagnetic hybrid conductor

    Energy Technology Data Exchange (ETDEWEB)

    Giroud, M.; Hasselbach, K.; Courtois, H.; Pannetier, B. [Centre de Recherche sur les Tres Basses Temperatures, CNRS, 38 - Grenoble (France); Mailly, D. [Laboratoire de Photonique et de Nanostructures, 91 - Marcoussis (France)

    2003-01-01

    We present electrical transport experiments performed on submicron hybrid devices made of a ferromagnetic conductor (Co) and a superconducting (Al) electrode. The sample was patterned in order to separate the contributions of the Co conductor and of the Co-Al interface. We observed a strong influence of the Al electrode superconductivity on the resistance of the Co conductor. This effect is large only when the interface is highly transparent. We characterized the dependence of the observed resistance decrease on temperature, bias current and magnetic field. As the differential resistance of the ferromagnet exhibits a non-trivial asymmetry, we claim that the magnetic domain structure plays an important role in the electron transport properties of superconducting / ferromagnetic conductors. (authors)

  5. Solid state proton conductors properties and applications in fuel cells

    CERN Document Server

    Knauth, Philippe

    2012-01-01

    Proton conduction can be found in many different solid materials, from organic polymers at room temperature to inorganic oxides at high temperature. Solid state proton conductors are of central interest for many technological innovations, including hydrogen and humidity sensors, membranes for water electrolyzers and, most importantly, for high-efficiency electrochemical energy conversion in fuel cells. Focusing on fundamentals and physico-chemical properties of solid state proton conductors, topics covered include: Morphology and Structure of Solid Acids Diffusion in Soli

  6. New resistivity for high-mobility quantum Hall conductors

    Science.gov (United States)

    Mceuen, P. L.; Szafer, A.; Richter, C. A.; Alphenaar, B. W.; Jain, J. K.

    1990-01-01

    Measurements showing dramatic nonlocal behavior in the four-terminal resistances of a high-mobility quantum Hall conductor are presented. These measurements illustrate that the standard definition of the resistivity tensor is inappropriate, but they are in excellent agreement with a new model of the conductor that treats the edge and bulk conducting pathways independently. This model uses a single intensive parameter, analogous to a local resistivity for the bulk channel only, to characterize the system.

  7. Modelling the transient emission from a twin conductor cable

    Directory of Open Access Journals (Sweden)

    Ian Brook Darney

    2016-03-01

    Full Text Available Using the equations of transmission line theory, a programme is developed to simulate the response of an open-circuit line to a step pulse. This is compared with the observed response of a twin-conductor cable. It is deduced that not all of the current delivered to the send conductor arrives back via the return conductor. Some of it departs in the form of radiated emission. A virtual capacitor is used to simulate this, with limited success. However, by adding a second virtual capacitor to simulate transient current being delivered from the return conductor back to the send conductor, a fair correlation is achieved between theoretical and actual results. This analysis demonstrates that the return conductor plays an active role in propagating any signal along the cable. This study also demonstrates that a circuit model can be created to simulate the mechanisms involved in the radiation of interference from power supply cables. This is but one example of the use of circuit models to analyse electromagnetic interference (EMI. The key relationship between electromagnetic theory and circuit theory which enables this technique to be used to analyse any EMI problem is identified. A dramatic simplification in the mathematics can be achieved.

  8. Electron quantum optics in ballistic chiral conductors

    Energy Technology Data Exchange (ETDEWEB)

    Bocquillon, Erwann; Freulon, Vincent; Parmentier, Francois D.; Berroir, Jean-Marc; Placais, Bernard; Feve, Gwendal [Laboratoire Pierre Aigrain, Ecole Normale Superieure, CNRS (UMR 8551), Universite Pierre et Marie Curie, Universite Paris Diderot, Paris (France); Wahl, Claire; Rech, Jerome; Jonckheere, Thibaut; Martin, Thierry [Aix Marseille Universite, CNRS, CPT, UMR 7332, Marseille (France); Universite de Toulon, CNRS, CPT, UMR 7332, La Garde (France); Grenier, Charles; Ferraro, Dario; Degiovanni, Pascal [Universite de Lyon, Federation de Physique Andre Marie Ampere, CNRS - Laboratoire de Physique de l' Ecole Normale Superieure de Lyon, Lyon (France)

    2014-01-15

    The edge channels of the quantum Hall effect provide one dimensional chiral and ballistic wires along which electrons can be guided in an optics-like setup. Electronic propagation can then be analyzed using concepts and tools derived from optics. After a brief review of electron optics experiments performed using stationary current sources which continuously emit electrons in the conductor, this paper focuses on triggered sources, which can generate on-demand a single particle state. It first outlines the electron optics formalism and its analogies and differences with photon optics and then turns to the presentation of single electron emitters and their characterization through the measurements of the average electrical current and its correlations. This is followed by a discussion of electron quantum optics experiments in the Hanbury-Brown and Twiss geometry where two-particle interferences occur. Finally, Coulomb interactions effects and their influence on single electron states are considered. (copyright 2013 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Internally heated convection beneath a poor conductor

    CERN Document Server

    Goluskin, David

    2016-01-01

    We consider convection in an internally heated layer of fluid that is bounded below by a perfect insulator and above by a poor conductor. The poorly conducting boundary is modelled by a fixed heat flux. Using solely analytical methods, we find linear and energy stability thresholds for the static state, and we construct a lower bound on the mean temperature that applies to all flows. The linear stability analysis yields a Rayleigh number above which the static state is linearly unstable ($R_L$), and the energy analysis yields a Rayleigh number below which it is globally stable ($R_E$). For various boundary conditions on the velocity, exact expressions for $R_L$ and $R_E$ are found using long-wavelength asymptotics. Each $R_E$ is strictly smaller than the corresponding $R_L$ but is within 1%. The lower bound on the mean temperature is proven for no-slip velocity boundary conditions using the background method. The bound guarantees that the mean temperature of the fluid, relative to that of the top boundary, gr...

  10. The ATLAS SemiConductorTracker

    CERN Document Server

    Mikuz, M

    2004-01-01

    The ATLAS SemiConductor Tracker (SCT) is presented. About 16000 silicon micro-strip sensors with a total active surface of over 60 m /sup 2/ and with 6.3 million read-out channels are built into 4088 modules arranged into four barrel layers and nine disks covering each of the forward regions up to an eta of 2.5. Challenges are imposed by the hostile radiation environment with particle fluences up to 2*10 /sup 14/ cm/sup -2/ 1 MeV neutron NIEL equivalent and 100 kGy TID, the 25 ns LHC bunch crossing time and the need for a hermetic, lightweight tracker. The solution adopted is carefully designed strip detectors operated at -7 degrees C, biased up to 500 V and read out by binary rad-hard fast BiCMOS electronics. A zero-CTE carbon fibre structure provides mechanical support. 30 kW of power are supplied on aluminium/Kapton tapes and cooled by C/sub 3/F/sub 8/ evaporative cooling. Data and commands are transferred by optical links. Prototypes of detector modules have been built, irradiated to the maximum expected ...

  11. Local electron heating in nanoscopic conductors

    Science.gov (United States)

    D'Agosta, Roberto; Sai, Na; di Ventra, Massimiliano

    2007-03-01

    The electron current density in nanoscale junctions is typically several orders of magnitude larger than the corresponding one in bulk electrodes. Consequently, the electron-electron scattering rate increases substantially in the junction. This leads to local electron heating of the underlying Fermi sea [1] in analogy to the local ionic heating that is due to the increased electron-phonon scattering rates [2]. By using a novel hydrodynamic formulation of transport [3], we predict the bias dependence of local electron heating in quasi-ballistic nanoscale conductors [1], its effect on ionic heating [1], and the consequent observable changes in the inelastic conductance [4]. [1] R. D'Agosta, N. Sai and M. Di Ventra, accepted in Nano Letters (2006). [2] Y.-C. Chen, M. Zwolak, and M. Di Ventra, Nano Lett. 3, 1961 (2003); Nano Lett. 4, 1709 (2004); Nano Lett. 5, 621 (2005). M. J. Montgomery, T. N. Todorov, and A. P. Sutton, J. Phys. Cond. Matt. 14, 5377 (2002). [3] R. D'Agosta and M. Di Ventra, J. Phys. Cond. Matt. in press. [4] R. D'Agosta and M. Di Ventra, in preparation.

  12. On electromagnetic induction in electric conductors

    CERN Document Server

    Korolev, Alexander I

    2013-01-01

    Experimental validation of the Faraday's law of electromagnetic induction (EMI) is performed when an electromotive force is generated in thin copper turns, located inside a large magnetic coil. It has been established that the electromotive force (emf) value should be dependent not only on changes of the magnetic induction flux through a turn and on symmetry of its crossing by magnetic power lines also. The law of EMI is applicable in sufficient approximation in case of the changes of the magnetic field near the turn are symmetrical. Experimental study of the induced emf in arcs and a direct section of the conductor placed into the variable field has been carried out. Linear dependence of the induced emf on the length of the arc has been ascertained in case of the magnetic field distribution symmetry about it. Influence of the magnetic field symmetry on the induced emf in the arc has been observed. The curve of the induced emf in the direct section over period of current pulse is similar to this one for the t...

  13. SYNTHESIS AND CHARACTERIZATION OF PROTON CONDUCTORS

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, K.

    2010-02-18

    The morphological and electrical properties of yttrium (Y) and indium (In) doped barium cerate perovskites of the form BaIn{sub 0.3-x}Y{sub x}Ce{sub 0.7}O{sub 3-{delta}} (with x=0-0.3) prepared by a modified Pechini method were investigated as potential high temperature proton conductors with improved chemical stability. The sinterability increased with the increase of In-doping, and the perovskite phase was found in the BaIn{sub 0.3-x}Y{sub x}Ce{sub 0.7}O{sub 3-{delta}} solid solutions over the range 0 {le} x {le} 0.3. The conductivities decreased (from x to x, insert quantitative values) while the tolerance to wet CO{sub 2} improved for BaIn{sub 0.3-x}Y{sub x}Ce{sub 0.7}O{sub 3-{delta}} samples with an increase of In-doping.

  14. “Pore-Like” Effects of Super-Molecular Self-Assembly on Molecular Diffusion of Poly(Ethylene Oxide-Poly(Propylene Oxide-Poly(Ethylene Oxide in Water

    Directory of Open Access Journals (Sweden)

    Konstantin Ulrich

    2012-05-01

    Full Text Available Molecular diffusion of triblock copolymers poly(ethylene oxide-poly(propylene oxide-poly(ethylene oxide in water was studied with the help of Pulsed Field Gradient NMR in the broad range of polymer weight fractions from 0.09 to 0.8. Owing to amphiphilic nature of the molecules, these block copolymers exhibit rich self-organization properties when mixed with water. In particular, at ambient temperatures they form micelles and three liquid crystalline mesophases: cubic, hexagonal, and lamellar. The corresponding super-molecular structure formations were studied with the same block copolymer and at the same temperature. Self-assembly of molecules was shown to produce “pore-like” effects on their self-diffusion properties by imposing severe constraints on the dimensionality of propagation. Diffusion in the hexagonal phase was shown to be quasi one-dimensional in the direction parallel to the long axis of the ordered molecular rods. In the lamellar phase, diffusion was found to be quasi two-dimensional, in the plane of the lamellar structures. The observed diffusion anisotropy was attributed to the effects of the specific molecular ordering on the mesoscopic length scale.

  15. Distinct kinetics of molecular gelation in a confined space and its relation to the structure and property of thin gel films.

    Science.gov (United States)

    Liu, Yu; Zhao, Wen-Jing; Li, Jing-Liang; Wang, Rong-Yao

    2015-03-28

    Thin films of molecular gels formed in a confined space have potential applications in transdermal delivery, artificial skin, molecular electronics, etc. The microstructures and properties of thin gel films can be significantly different from those of their bulk counterparts. However, so far a comprehensive understanding of the effects of spatial confinement on the molecular gelation kinetics, fiber network structure and related mechanical properties is still lacking. In this work, using rheological techniques, we investigated the effect of one-dimensional confinement on the formation kinetics of fiber networks in the molecular gelation process. Fractal analyses of the kinetic information in terms of an extended Dickinson model enabled us to describe quantitatively the distinct kinetic signature of molecular gelation. The structural features derived from gelation kinetics support well the fractal patterns of the fiber networks acquired by optical and electron microscopy. With the kinetics-structure correlation, we can gain an in-depth understanding of the confinement-induced differences in the structure and consequently the mechanical properties of a model molecular gelling system. Particularly, the confinement induced structural transition, from a three-dimensional, dense and compact spherulitic network composed of highly branched fibers to a quasi-two-dimensional sparse spherulitic network composed of less branched fibers and entangled fibrils at the boundary areas, renders a gel film to become less stiff but more ductile. Our study suggests here a new strategy of engineering the fiber network microstructure to achieve functional gel films with unusual but useful properties.

  16. Charge fluctuation, charge ordering, and zero-gap state in organic conductors

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Toshihiro, E-mail: toshi.takahashi@gakushuin.ac.jp [Department of Physics, Gakushuin University, Mejiro 1-5-1, Toshima-ku, Tokyo 171-8588 (Japan)

    2012-06-01

    We have carried out a series of measurements of angular dependence of solid-state NMR spectrum using single crystal samples on various organic molecular conductors, in order to investigate the natures of the electronic states at low temperatures. We confirmed a charge ordered insulating state in {alpha}-(BEDT-TTF){sub 2}I{sub 3} and large charge disproportionation in the metallic state of this salt. In another charge ordered system, {theta}-(BEDT-TTF){sub 2}RbZn(SCN){sub 4}, we observed unusual NMR line broadening, proportional to resonance shift, in the metallic state above the transition. We found that this broadening is due to charge disproportionation, or more correctly, due to the inhomogeneity of local susceptibility at nuclear sites and analyzed its dynamics. We observed similar broadening in various organic molecular conductors as well, such as {theta}-(BEDT-TTF){sub 2}CsZn(SCN){sub 4}, an exotic Bechgaad salt, (TMTSF){sub 2}FSO{sub 3}, and {lambda}-type BETS salts, {lambda}-(BETS){sub 2}(Fe,Ga)Cl{sub 4}. We found the mechanism of CD in each system is different, respectively.

  17. Synergistic, ultrafast mass storage and removal in artificial mixed conductors

    Science.gov (United States)

    Chen, Chia-Chin; Fu, Lijun; Maier, Joachim

    2016-08-01

    Mixed conductors—single phases that conduct electronically and ionically—enable stoichiometric variations in a material and, therefore, mass storage and redistribution, for example, in battery electrodes. We have considered how such properties may be achieved synergistically in solid two-phase systems, forming artificial mixed conductors. Previously investigated composites suffered from poor kinetics and did not allow for a clear determination of such stoichiometric variations. Here we show, using electrochemical and chemical methods, that a melt-processed composite of the ‘super-ionic’ conductor RbAg4I5 and the electronic conductor graphite exhibits both a remarkable silver excess and a silver deficiency, similar to those found in single-phase mixed conductors, even though such behaviour is not possible in the individual phases. Furthermore, the kinetics of silver uptake and release is very fast. Evaluating the upper limit set by interfacial ambipolar diffusion reveals chemical diffusion coefficients that are even higher than those achieved for sodium chloride in bulk liquid water. These results could potentially stimulate systematic research into powerful, even mesoscopic, artificial mixed conductors.

  18. Design of force-cooled conductors for large fusion magnets

    Energy Technology Data Exchange (ETDEWEB)

    Dresner, L.; Lue, J.W.

    1977-01-01

    Conductors cooled by supercritical helium in forced convection are under active consideration for large toroidal fusion magnets. One of the central problems in designing such force cooled conductors is to maintain an adequate stability margin while keeping the pumping power tolerably low. A method has been developed for minimizing the pumping power for fixed stability by optimally choosing the matrix-to-superconductor and the metal-to-helium ratios. Such optimized conductors reduce pumping power requirements for fusion size magnets to acceptable limits. Furthermore, the mass flow and hence pumping losses can be varied through a magnet according to the local magnetic field and magnitude of desired stability margin. Force cooled conductors give flexibility in operation, permitting, for example, higher fields to be obtained than originally intended by lowering the bath temperature or increasing the pumping power or both. This flexibility is only available if the pumping power is low to begin with. Scaling laws for the pumping requirement and stability margin as functions of operating current density, number of strands and such physical parameters as stabilizer resistivity and critical current density, have been proved. Numerical examples will be given for design of conductors intended for use in large toroidal fusion magnet systems.

  19. The fate of sounds in conductors' brains: an ERP study.

    Science.gov (United States)

    Nager, Wido; Kohlmetz, Christine; Altenmüller, Eckart; Rodriguez-Fornells, Antoni; Münte, Thomas F

    2003-06-01

    Professional music conductors are required to home in on a particular musician but at the same time have to monitor the entire orchestra. It was hypothesized that this unique experience should be reflected by superior auditory spatial processing. Event-related brain potentials were obtained, while conductors, professional pianists, and non-musicians listened to sequences of bandpass-filtered noise-bursts presented in random order from six speakers, three located in front and three to the right of the subjects. In different runs, subjects either attended the centermost or the most peripheral speaker in order to detect slightly deviant noise-bursts. For centrally located speakers, the ERPs showed a typical Nd attention effect for the relevant location with a steep decline for the neighboring speakers in all subject groups. For peripheral speakers, only the conductors showed attentional selectivity, while the Nd effect was of similar size for all three peripheral speakers in the other two groups. These ERP effects were paralleled by an enhanced behavioral selectivity in peripheral auditory space in conductors. Moreover, the pre-attentive monitoring of the entire auditory scene indexed by the mismatch negativity was superior in musicians compared to non-musicians. In conductors, the MMN was followed by a positivity suggesting an attention shift towards the deviant stimuli in this group only.

  20. Hearing status among Norwegian train drivers and train conductors.

    Science.gov (United States)

    Lie, A; Skogstad, M; Johnsen, T S; Engdahl, B; Tambs, K

    2013-12-01

    There is a general perception that train drivers and conductors may be at increased risk of developing noise-induced hearing loss. To study job-related hearing loss among train drivers and train conductors. Audiograms from train drivers and train conductors were obtained from the medical records of the occupational health service of the major Norwegian railway company. The results were compared with audiograms from an internal control group of railway workers and an external reference group of people not occupationally exposed to noise. The monaural hearing threshold level at 4kHz, the mean binaural value at 3, 4 and 6kHz and the prevalence of audiometric notches (≥25 dB at 4kHz) were used for comparison. Audiograms were available for 1567 drivers, 1565 conductors, 4029 railway worker controls and 15 012 people not occupationally exposed to noise. No difference in hearing level or prevalence of audiometric notches was found between study groups after adjusting for age and gender. Norwegian train drivers and conductors have normal hearing threshold levels comparable with those in non-exposed groups.

  1. Loss and Inductance Investigation in Superconducting Cable Conductors

    DEFF Research Database (Denmark)

    Olsen, Søren Krüger; Tønnesen, Ole; Træholt, Chresten

    1999-01-01

    An important parameter in the design and optimization of a superconducting cable conductor is the control of the current distribution among single tapes and layers. This distribution is to a large degree determined by inductances, since the resistances are low. The self and mutual inductances...... of the layers are therefore studied theoretically. The current distribution between the superconducting layers is monitored as a function of transport current, and the results are compared with the expected current distribution given by our electrical circuit model.The AC-losses are measured as a function...... of transport current and current distribution.This presentation is based on a number of experiments performed on prototype superconducting cable conductors. The critical current (1uV/cm) of the conductor at 77K was 1590 A (cable #1) and 3240 A (cable #2) respectively.At an rms current of 2 kA (50 Hz) the AC...

  2. Spectroscopic investigation of some building blocks of organic conductors: A comparative study

    Science.gov (United States)

    Mukherjee, V.; Yadav, T.

    2017-04-01

    Theoretical molecular structures and IR and Raman spectra of di and tetra methyl substituted tetrathiafulvalene and tetraselenafulvalene molecules have been studied. These molecules belong to the organic conductor family and are immensely used as building blocks of several organic conducting devices. The Hartree-Fock and density functional theory with exchange functional B3LYP have been employed for computational purpose. We have also performed normal coordinate analysis to scale the theoretical frequencies and to calculate potential energy distributions for the conspicuous assignments. The exciting frequency and temperature dependent Raman spectra have also presented. Optimization results reveal that the sulphur derivatives possess boat shape while selenium derivatives possess planner structures. Natural bond orbitals analysis has also been performed to study second order interaction between donors and acceptors and to compute molecular orbital occupancy and energy.

  3. Air-Stable n-type Conductors and Semiconductors

    Science.gov (United States)

    2015-07-14

    AFRL-OSR-VA-TR-2015-0209 Air-Stable n-type Conductors and Semiconductors Zhenan Bao LELAND STANFORD JUNIOR UNIVERSITY THE Final Report 07/14/2015...04-2012 to 14-04-2015 4. TITLE AND SUBTITLE Air-Stable n-type Conductors and Semiconductors 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-12-1-0190 5c...2. Design rules and synthesis of high performance n-doped conducting polymers; 3. Fundamental understanding of organic semiconductors through

  4. The Joule-Thomson effect on the thermoelectric conductors

    Energy Technology Data Exchange (ETDEWEB)

    Consiglieri, Luisa [Lisbon Univ. (Portugal). Dept. of Mathematics and CMAF

    2009-03-15

    The transmission of an electric current in a conductor is a process in which some electrical energy is converted into heat (thermal energy). We deal with a nonlinear boundary value elliptic problem which describes the electrical heating of a solid conductor and the Joule-Thomson effect is taken into account. The existence of a weak solution is proved under both space and temperature dependence of the electrical and thermal conductivities. When the coefficients are only dependent on their temperature argument, some regularity results are stated. (orig.)

  5. Improvement of SOFC electrodes using mixed ionic-electronic conductors

    Energy Technology Data Exchange (ETDEWEB)

    Matsuzaki, Y.; Hishinuma, M. [Tokyo Gas Co., Ltd. (Japan)

    1996-12-31

    Since the electrode reaction of SOFC is limited to the proximity of a triple phase boundary (TPB), the local current density at the electrode and electrolyte interface is larger than mean current density, which causes large ohmic and electrode polarization. This paper describes an application of mixed ionic-electronic conductors to reduce such polarization by means of (1) enhancing ionic conductivity of the electrolyte surface layer by coating a high ionic conductors, and (2) reducing the local current density by increasing the electrochemically active sites.

  6. Study on Quench Protection of a Coil Wound of YBCO Coated Conductors

    Institute of Scientific and Technical Information of China (English)

    FUYoukun

    2003-01-01

    Owing to recent progress of long YBCO coated conductors, coils wound of YBCO conductors will be developed in near future.Compared with coils wound of LTS conductom, coils wound of HTS conductors operated at higher temperature are hard to be quenched. However, measures for quench protection are still necessary. Especially YBCO coated conductors that are made by deposition of thin YBCO film on Ni based alloy substrates such as Hastelloy tapes are highly resistive when they are quenched, Therefore,

  7. 30 CFR 57.12005 - Protection of power conductors from mobile equipment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protection of power conductors from mobile... NONMETAL MINES Electricity Surface and Underground § 57.12005 Protection of power conductors from mobile equipment. Mobile equipment shall not run over power conductors, nor shall loads be dragged over...

  8. 30 CFR 57.12069 - Lightning protection for telephone wires and ungrounded conductors.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Lightning protection for telephone wires and ungrounded conductors. 57.12069 Section 57.12069 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... ungrounded conductors. Each ungrounded conductor or telephone wire that leads underground and is...

  9. 30 CFR 77.508 - Lightning arresters, ungrounded and exposed power conductors and telephone wires.

    Science.gov (United States)

    2010-07-01

    ... power conductors and telephone wires. 77.508 Section 77.508 Mineral Resources MINE SAFETY AND HEALTH... arresters, ungrounded and exposed power conductors and telephone wires. All ungrounded, exposed power conductors and telephone wires shall be equipped with suitable lightning arresters which are...

  10. 30 CFR 56.12069 - Lightning protection for telephone wires and ungrounded conductors.

    Science.gov (United States)

    2010-07-01

    ... ungrounded conductors. 56.12069 Section 56.12069 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... NONMETAL MINES Electricity § 56.12069 Lightning protection for telephone wires and ungrounded conductors. Each ungrounded power conductor or telephone wire that leads underground and is directly exposed...

  11. 30 CFR 75.521 - Lightning arresters; ungrounded and exposed power conductors and telephone wires.

    Science.gov (United States)

    2010-07-01

    ... power conductors and telephone wires. 75.521 Section 75.521 Mineral Resources MINE SAFETY AND HEALTH... Electrical Equipment-General § 75.521 Lightning arresters; ungrounded and exposed power conductors and telephone wires. Each ungrounded, exposed power conductor and each ungrounded, exposed telephone wire...

  12. 30 CFR 75.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Science.gov (United States)

    2010-07-01

    ... conduits enclosing power conductors. 75.700 Section 75.700 Mineral Resources MINE SAFETY AND HEALTH... Grounding § 75.700 Grounding metallic sheaths, armors, and conduits enclosing power conductors. All metallic sheaths, armors, and conduits enclosing power conductors shall be electrically continuous throughout...

  13. 30 CFR 57.12010 - Isolation or insulation of communication conductors.

    Science.gov (United States)

    2010-07-01

    ... conductors. 57.12010 Section 57.12010 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF... conductors. Telephone and low-potential signal wire shall be protected, by isolation or suitable insulation, or both, from contacting energized power conductors or any other power source....

  14. 30 CFR 77.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Science.gov (United States)

    2010-07-01

    ... conduits enclosing power conductors. 77.700 Section 77.700 Mineral Resources MINE SAFETY AND HEALTH..., and conduits enclosing power conductors. Metallic sheaths, armors, and conduits enclosing power conductors shall be electrically continuous throughout and shall be grounded by methods approved by...

  15. 30 CFR 75.1002 - Installation of electric equipment and conductors; permissibility.

    Science.gov (United States)

    2010-07-01

    ... conductors; permissibility. 75.1002 Section 75.1002 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... Wires and Trolley Feeder Wires § 75.1002 Installation of electric equipment and conductors... equipment is located within 150 feet of pillar workings or longwall faces. (b) Electric conductors...

  16. Application Research on Drag Reduced Conductors for Electric Power Transmission Lines in Strong Wind Areas

    Directory of Open Access Journals (Sweden)

    Li Dong Qing

    2016-01-01

    Full Text Available The breeze vibration duration of conductors is long, the vibration amplitude is strong and the frequency range is wide for electric power transmission lines in strong wind areas, which seriously affects the safe and stable operation of transmission lines. There are two design schemes of conductors which can achieve the purpose of reducing wind-induced disaster. One is enhancing the structural strength of conductors to withstand wind load, but the investment is enormous and the effect is limited. The other is developing drag reduced conductors to reduce wind load by changing conductor structure. This paper started from application feasibility analysis of drag reduced conductors and designed four drag reduced conductors by structure optimization of the conventional aluminium conductor steel reinforced JL/G1A-630/45-45/7, denoted as DFY630/45(45°-R3.5, DFY630/45(60°-R3.5, DFY630/45(45°–R3.2 and DFY630/45(60°-R3.2, respectively. The wind tunnel test was performed and the wind resistance coefficients in unit length of five conductors were compared. Result showed that the wind resistance coefficients in unit length of four drag reduced conductors were obviously lower than that of the conventional conductor. By controlling the manufacturing process, popularization and application of drag reduced conductors for transmission lines in strong wind areas can be realized.

  17. Low-frequency scattering from two-dimensional perfect conductors

    DEFF Research Database (Denmark)

    Hansen, Thorkild; Yaghjian, A.D

    1991-01-01

    Exact expressions have been obtained for the leading terms in the low-frequency expansions of the far fields scattered from three different types of two-dimensional perfect conductors: a cylinder with finite cross section, a cylindrical bump on an infinite ground plane, and a cylindrical dent...

  18. Solutions of Maxwell equations for hollow curved wave conductor

    CERN Document Server

    Bashkov, V I

    1995-01-01

    In the present paper the idea is proposed to solve Maxwell equations for a curved hollow wave conductor by means of effective Riemannian space, in which the lines of motion of fotons are isotropic geodesies for a 4-dimensional space-time. The algorithm of constructing such a metric and curvature tensor components are written down explicitly. The result is in accordance with experiment.

  19. Effects of volume conductor and source configuration on simulated magnetogastrograms

    Energy Technology Data Exchange (ETDEWEB)

    Komuro, Rie; Qiao Wenlian; Pullan, Andrew J; Cheng, Leo K, E-mail: l.cheng@auckland.ac.n [Auckland Bioengineering Institute, University of Auckland, Auckland (New Zealand)

    2010-11-21

    Recordings of the magnetic fields (MFs) arising from gastric electrical activity (GEA) have been shown to be able to distinguish between normal and certain abnormal GEA. Mathematical models provide a powerful tool for revealing the relationship between the underlying GEA and the resultant magnetogastrograms (MGGs). However, it remains uncertain the relative contributions that different volume conductor and dipole source models have on the resultant MFs. In this study, four volume conductor models (free space, sphere, half space and an anatomically realistic torso) and two dipole source configurations (containing 320 moving dipole sources and a single equivalent moving dipole source) were used to simulate the external MFs. The effects of different volume conductor models and dipole source configurations on the MF simulations were examined. The half space model provided the best approximation of the MFs produced by the torso model in the direction normal to the coronal plane. This was despite the fact that the half space model does not produce secondary sources, which have been shown to contribute up to 50% of the total MFs when an anatomically realistic torso model was used. We conclude that a realistic representation of the volume conductor and a detailed dipole source model are likely to be necessary when using a model-based approach for interpreting MGGs.

  20. Conductor and Ensemble Performance Expressivity and State Festival Ratings

    Science.gov (United States)

    Price, Harry E.; Chang, E. Christina

    2005-01-01

    This study is the second in a series examining the relationship between conducting and ensemble performance. The purpose was to further examine the associations among conductor, ensemble performance expressivity, and festival ratings. Participants were asked to rate the expressivity of video-only conducting and parallel audio-only excerpts from a…

  1. Influence of the magnetic field profile on ITER conductor testing

    NARCIS (Netherlands)

    Nijhuis, A.; Ilyin, Y.; Kate, ten H.H.J.

    2006-01-01

    We performed simulations with the numerical CUDI-CICC code on a typical short ITER (International Thermonuclear Experimental Reactor) conductor test sample of dual leg configuration, as usually tested in the SULTAN test facility, and made a comparison with the new EFDA-Dipole test facility offering

  2. Center conductor diagnostic for multipactor detection in inaccessible geometries

    Science.gov (United States)

    Chaplin, Vernon H.; Hubble, Aimee A.; Clements, Kathryn A.; Graves, Timothy P.

    2017-01-01

    Electron collecting current probes are the most reliable diagnostic of multipactor and radiofrequency (RF) ionization breakdown; however, stand-alone probes can only be used in test setups where the breakdown region is physically accessible. This paper describes techniques for measuring multipactor current directly on the center conductor of a coaxial RF device (or more generally, on the signal line in any two-conductor RF system) enabling global multipactor detection with improved sensitivity compared to other common diagnostics such as phase null, third harmonic, and reflected power. The center conductor diagnostic may be AC coupled for use in systems with a low DC impedance between the center conductor and ground. The effect of DC bias on the breakdown threshold was studied: in coaxial geometry, the change in threshold was positive biases satisfying VD C/VR F 0 effectively with no bias at all—this is the preferred implementation, but biases in the range VD C=0 -10 V may be applied if necessary. The polarity of the detected current signal may be positive or negative depending on whether there is net electron collection or emission globally.

  3. Elementary charge-transfer processes in mesoscopic conductors

    NARCIS (Netherlands)

    Vanević, M.; Nazarov, Y.V.; Belzig, W.

    2008-01-01

    We determine charge-transfer statistics in a quantum conductor driven by a time-dependent voltage and identify the elementary transport processes. At zero temperature unidirectional and bidirectional single-charge transfers occur. The unidirectional processes involve electrons injected from the sour

  4. Polaron effects in the protonic conductor hydrogen uranyl phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Lupu, D. (Inst. of Isotopic and Molecular Technology, Cluj-Napoca (Romania)); Grecu, R. (Inst. of Chemistry, Cluj-Napoca (Romania)); Biris, A.R. (Inst. of Isotopic and Molecular Technology, Cluj-Napoca (Romania))

    1993-08-01

    The isotope effects on the conductivity of hydrogen uranyl phosphate reveal ionic polaron effects in this solid protonic conductor, in agreement with the small polaron theory. An absorption band is observed at 0.67 eV, which can be correlated with the conduction mechanism consisting in both tunnelling and over-barrier hopping processes. (orig.)

  5. Low resistive trasparent conductors with metallic grids : modeling and experiments

    NARCIS (Netherlands)

    Deelen, J. van; Rendering, H.; Mannetje, H.H 't; Klerk, L.; Hovestad, A.

    2012-01-01

    At present, transparent conducting oxides (TCOs) are still superior in performance to most other transparent conductors. Results on opto-electronic modeling and design optimization of TCOs are presented using a monolithically integrated CIGS cell configuration as case. For various cell dimensions an

  6. Metallic grids for low resistive transparent conductors: modeling and experiments

    NARCIS (Netherlands)

    Deelen, J. van; Rendering, H.; Mannetje, H. het; Klerk, L.; Hovestad, A.

    2012-01-01

    At present, transparent conducting oxides (TCOs) are still superior in performance to most other transparent conductors. Results on opto-electronic modeling and design optimization of TCOs are presented using a monolithically integrated CIGS cell configuration as case. For various cell dimensions an

  7. Attentional flexibility and memory capacity in conductors and pianists.

    Science.gov (United States)

    Wöllner, Clemens; Halpern, Andrea R

    2016-01-01

    Individuals with high working memory (WM) capacity also tend to have better selective and divided attention. Although both capacities are essential for skilled performance in many areas, evidence for potential training and expertise effects is scarce. We investigated the attentional flexibility of musical conductors by comparing them to equivalently trained pianists. Conductors must focus their attention both on individual instruments and on larger sections of different instruments. We studied students and professionals in both domains to assess the contributions of age and training to these skills. Participants completed WM span tests for auditory and visual (notated) pitches and timing durations, as well as long-term memory tests. In three dichotic attention tasks, they were asked to detect small pitch and timing deviations from two melodic streams presented in baseline (separate streams), selective-attention (concentrating on only one stream), and divided-attention (concentrating on targets in both streams simultaneously) conditions. Conductors were better than pianists in detecting timing deviations in divided attention, and experts detected more targets than students. We found no group differences for WM capacity or for pitch deviations in the attention tasks, even after controlling for the older age of the experts. Musicians' WM spans across multimodal conditions were positively related to selective and divided attention. High-WM participants also had shorter reaction times in selective attention. Taken together, conductors showed higher attentional flexibility in successfully switching between different foci of attention.

  8. An Organic Mixed Ion–Electron Conductor for Power Electronics

    DEFF Research Database (Denmark)

    Malti, Abdellah; Edberg, Jesper; Granberg, Hjalmar

    2016-01-01

    A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting...

  9. An Organic Mixed Ion-Electron Conductor for Power Electronics

    DEFF Research Database (Denmark)

    Malti, Abdellah; Edberg, Jesper; Granberg, Hjalmar

    2016-01-01

    A mixed ionic–electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio­phene):­poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting...

  10. Molecular dynamics simulations of quasi-brittle crack development in iron

    Energy Technology Data Exchange (ETDEWEB)

    Borodin, V.A., E-mail: borodin@dni.polin.kiae.su [Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); NRC Kurchatov Institute, Kurchatov Sq. 1, 123182 Moscow (Russian Federation); Vladimirov, P.V., E-mail: Pavel.Vladimirov@kit.edu [Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany)

    2011-08-31

    The paper presents the results of molecular dynamics (MD) simulations of three-dimensional kinetics of micro-crack propagation in alpha-iron and the accompanying lattice transformations at the crack tips. We show that crack initiation on {l_brace}0 0 1{r_brace} planes in iron is preceded with the emission of compact slip bands from the pre-crack tips, in agreement with the predictions of the earlier quasi-two-dimensional simulations. The application of Voronoi decomposition technique for atomic short-range order processing has allowed us to clarify the kinetics of structural transformations at the tips of nucleating and propagating cracks for three most common systems of crack propagation in iron. It is demonstrated that the compact slip bands emanating from the crack tips not only accompany crack nucleation, but remain an essential feature of the crack propagation on {l_brace}0 0 1{r_brace} planes. Due to the strong coupling between the crack tip and slip band propagation, the crack propagation can be limited by slip band interaction with microstructural obstacles, abundantly created in ferritic-martensitic steels in radiation environment of nuclear facilities.

  11. Homogeneous nucleation and microstructure evolution in million-atom molecular dynamics simulation.

    Science.gov (United States)

    Shibuta, Yasushi; Oguchi, Kanae; Takaki, Tomohiro; Ohno, Munekazu

    2015-08-27

    Homogeneous nucleation from an undercooled iron melt is investigated by the statistical sampling of million-atom molecular dynamics (MD) simulations performed on a graphics processing unit (GPU). Fifty independent instances of isothermal MD calculations with one million atoms in a quasi-two-dimensional cell over a nanosecond reveal that the nucleation rate and the incubation time of nucleation as functions of temperature have characteristic shapes with a nose at the critical temperature. This indicates that thermally activated homogeneous nucleation occurs spontaneously in MD simulations without any inducing factor, whereas most previous studies have employed factors such as pressure, surface effect, and continuous cooling to induce nucleation. Moreover, further calculations over ten nanoseconds capture the microstructure evolution on the order of tens of nanometers from the atomistic viewpoint and the grain growth exponent is directly estimated. Our novel approach based on the concept of "melting pots in a supercomputer" is opening a new phase in computational metallurgy with the aid of rapid advances in computational environments.

  12. Structure Design and Service Performance Study of Low Wind-pressure Conductor

    Directory of Open Access Journals (Sweden)

    Wang Zhao Lin

    2016-01-01

    Full Text Available The low wind-pressure conductor is a dedicated conductor which obtains low wind resistance coefficient by changing the sectional shape of the conductor and has extensive application prospect in electric power transmission lines in strong wind areas. Previous wind tunnel testing results showed that the wind resistance coefficient in unit length of the low wind-pressure aluminium conductor steel reinforced was obviously lower than that of the conventional aluminium conductor steel reinforced, and the control factors of manufacturing process of the low wind-pressure conductor were proposed. In this paper, the low wind-pressure aluminium conductor steel reinforced JLX1/G1A(DFY–680/45–338 was designed based on the structure optimization of the conventional aluminium conductor steel reinforced JL/G1A–630/45–45/7, and the service performance study of the conductor was carried out. Results showed that the mechanical properties, electrical properties and construction properties of the low wind-pressure conductor fully satisfied service requirements, and the conductor can be popularized and applied for transmission lines in strong wind areas.

  13. Magnetic breakdown in the organic conductor α-(BEDT-TTF)2KHg(SCN)4 in magnetic fields of up to 60 T

    Science.gov (United States)

    Honold, M. M.; Harrison, N.; Nam, M.-S.; Singleton, J.; Mielke, C. H.; Kurmoo, M.; Day, P.

    1998-09-01

    de Haas-van Alphen experiments on α-(BEDT-TTF)2KHg(SCN)4 in fields of up to 60 T reveal oscillations of the β frequency, a clear indication of magnetic breakdown at fields well above the kink transition. A study of the amplitude of the oscillations shows that the gap between the quasi-one-dimensional and quasi-two-dimensional Fermi-surface sheets is significantly smaller than predicted by band-structure calculations. We consider the implications for the spin-density-wave nesting and the quantum Hall effect.

  14. A Testing Platform for Validation of Overhead Conductor Aging Models and Understanding Thermal Limits

    Energy Technology Data Exchange (ETDEWEB)

    Irminger, Philip [ORNL; Starke, Michael R [ORNL; Dimitrovski, Aleksandar D [ORNL; Young II, Marcus Aaron [ORNL; Rizy, D Tom [ORNL; Stovall, John P [ORNL; Overholt, Philip N [U.S. Department of Energy, Office of Electricity Delivery and Energy Reliability (OE)

    2014-01-01

    Power system equipment manufacturers and researchers continue to experiment with novel overhead electric conductor designs that support better conductor performance and address congestion issues. To address the technology gap in testing these novel designs, Oak Ridge National Laboratory constructed the Powerline Conductor Accelerated Testing (PCAT) facility to evaluate the performance of novel overhead conductors in an accelerated fashion in a field environment. Additionally, PCAT has the capability to test advanced sensors and measurement methods for accessing overhead conductor performance and condition. Equipped with extensive measurement and monitoring devices, PCAT provides a platform to improve/validate conductor computer models and assess the performance of novel conductors. The PCAT facility and its testing capabilities are described in this paper.

  15. Hydrogen Energy by Means of Proton Conductors

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf

    , but matching supply and demand in time as well as in form calls for new engineering solutions. Hydrogen as energy carrier and energy storage medium has often been mentioned as an option for the future. A protons is an elementary particles, but at the same time the ion of hydrogen. When hydrogen (H2......) is extracted from water (H2O) it can happen via formation of protons (hydrogen ions, H+) which must be transported away by proton conducting materials to form molecular hydrogen (H2). This process is called electrolysis and converts electrical energy into the chemical energy of a fuel. The reverse process...

  16. Frustrated spin-1/2 molecular magnetism in the mixed-valence antiferromagnets Ba3M Ru2O9 (M =In , Y, Lu)

    Science.gov (United States)

    Ziat, D.; Aczel, A. A.; Sinclair, R.; Chen, Q.; Zhou, H. D.; Williams, T. J.; Stone, M. B.; Verrier, A.; Quilliam, J. A.

    2017-05-01

    We have performed magnetic susceptibility, heat capacity, muon spin relaxation, and neutron-scattering measurements on three members of the family Ba3M Ru2O9 , where M =In , Y, and Lu. These systems consist of mixed-valence Ru dimers on a triangular lattice with antiferromagnetic interdimer exchange. Although previous work has argued that charge order within the dimers or intradimer double exchange plays an important role in determining the magnetic properties, our results suggest that the dimers are better described as molecular units due to significant orbital hybridization, resulting in one spin-1/2 moment distributed equally over the two Ru sites. These molecular building blocks form a frustrated, quasi-two-dimensional triangular lattice. Our zero- and longitudinal-field μ SR results indicate that the molecular moments develop a collective, static magnetic ground state, with oscillations of the zero-field muon spin polarization indicative of long-range magnetic order in the Lu sample. The static magnetism is much more disordered in the Y and In samples, but they do not appear to be conventional spin glasses.

  17. H/D isotope effects in high temperature proton conductors

    DEFF Research Database (Denmark)

    Bonanos, Nikolaos; Huijser, A.; Poulsen, Finn Willy

    2015-01-01

    The atomic mass ratio of ca. 2 between deuterium and hydrogen is the highest for any pair of stable isotopes and results in significant and measurable H/D isotope effects in high temperature proton conductors containing these species. This paper discusses H/D isotope effects manifested in O......-H/O-D vibration frequencies, the mobility of H+/D+ carriers, the kinetics of the electrochemical oxidation of H2/D2, the solubilities of H2O/D2O and, finally, the spontaneous electromotive force that appears across H2/D2 cells with proton conducting electrolytes. Comparable work on tritium-exchanged materials...... is also discussed. The results highlight the usefulness of isotope effects in the study of high temperature proton conductors....

  18. Critical area computation for real defects and arbitrary conductor shapes

    Institute of Scientific and Technical Information of China (English)

    Wang Jun-Ping; Hao Yue

    2006-01-01

    In current critical area models, it is generally assumed the defect outlines are circular and the conductors to be rectangle or the merger of rectangles. However, real defects and conductors associated with optimal layout design exhibit a great variety of shapes. Based on mathematical morphology, a new critical area model is presented, which can be used to estimate the critical area of short circuit, open circuit and pinhole. Based on the new model, the efficient validity check algorithms are explored to extract critical areas of short circuit, open circuit and pinhole from layouts.The results of experiment on an approximate layout of 4 × 4 shifts register show that the new model predicts the critical areas accurately. These results suggest that the proposed model and algorithm could provide new approaches for yield prediction.

  19. Structural Parameter Optimization of Multilayer Conductors in HTS Cable

    Institute of Scientific and Technical Information of China (English)

    Yan Mao; Jie Qiu; Xin-Ying Liu; Zhi-Xuan Wang; Shu-Hong Wang; Jian-Guo Zhu; You-Guang Guo; Zhi-Wei Lin; Jian-Xun Jin

    2008-01-01

    In this paper, the design optimization of the structural parameters of multilayer conductors in high temperature superconducting (HTS) cable is reviewed. Various optimization methods, such as the particle swarm optimization (PSO), the genetic algorithm (GA), and a robust optimization method based on design for six sigma (DFSS), have been applied to realize uniform current distribution among the multi- layer HTS conductors. The continuous and discrete variables, such as the winding angle, radius, and winding direction of each layer, are chosen as the design parameters. Under the constraints of the mechanical properties and critical current, PSO is proven to be a more powerful tool than GA for structural parameter optimization, and DFSS can not only achieve a uniform current distribution, but also improve significantly the reliability and robustness of the HTS cable quality.

  20. Mixed protonic and electronic conductors hybrid oxide synaptic transistors

    Science.gov (United States)

    Fu, Yang Ming; Zhu, Li Qiang; Wen, Juan; Xiao, Hui; Liu, Rui

    2017-05-01

    Mixed ionic and electronic conductor hybrid devices have attracted widespread attention in the field of brain-inspired neuromorphic systems. Here, mixed protonic and electronic conductor (MPEC) hybrid indium-tungsten-oxide (IWO) synaptic transistors gated by nanogranular phosphorosilicate glass (PSG) based electrolytes were obtained. Unique field-configurable proton self-modulation behaviors were observed on the MPEC hybrid transistor with extremely strong interfacial electric-double-layer effects. Temporally coupled synaptic plasticities were demonstrated on the MPEC hybrid IWO synaptic transistor, including depolarization/hyperpolarization, synaptic facilitation and depression, facilitation-stead/depression-stead behaviors, spiking rate dependent plasticity, and high-pass/low-pass synaptic filtering behaviors. MPEC hybrid synaptic transistors may find potential applications in neuron-inspired platforms.

  1. MOLECULAR WEIGHT DEPENDENCE OF CRYSTAL PATTERN TRANSITIONS OF POLY(ETHYLENE OXIDE)

    Institute of Scientific and Technical Information of China (English)

    Guo-liang Zhang; Liu-xin Jin; Ping Zheng; Wei Wang; Xiao-jing Wen

    2013-01-01

    Crystal patterns in ultrathin films of six poly(ethylene oxide) fractions with molecular weights from 25000 to 932000 g/mol were characterized within crystallization temperature range from 20 ℃ to 60 ℃.Labyrinthine,dendritic and faceted crystal patterns were observed in different temperature ranges,and then labyrinthine-to-dendritic and dendritic-tofaceted transition temperatures TL-D and TD-F were quantitatively identified.Their molecular weight dependences are TL-D(Mw) =TL-D(∞)-KL-D/Mw,where TL-D(∞) =38.2 ℃ and KL-D =253000 ℃·g/mol and TD-F(Mw) =TD-F(∞)-KD-F/Mw,where TD-F(∞) =54.7 ℃ and KD-F =27000 ℃·g/mol.Quasi two-dimensional blob models were proposed to provide empirical explanations of the molecular weight dependences.The labyrinthine-to-dendritic transition is attributed to a molecular diffusion process change from a local-diffusion to diffusion-limited-aggregation (DLA) and a polymer chain with Mw ≈ 253000 g/mol within a blob can join crystals independently.The dendritic-to-faceted transition is attributed to a turnover of the pattern formation mechanism from DLA to crystallization control,and a polymer chain with a Mw ≈ 27000g/mol as an independent blob crosses to a depletion zone to join crystals.These molecular weight dependences reveal a macromolecular effect on the crystal pattern formation and selection of crystalline polymers.

  2. ADIDAS CONDUCTOR HI 配色美学

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    ADIDAS将于2010年春季推出以80年代香篮球鞋为设计灵感的CONDUCTOR HI,材质上不仅使用了皮革及魔皮想互衬托在配色上更是用出了神秘的黑色以及极富质感 的咖啡配色,质感不俗。

  3. Numerical Analysis of Conductor Galloping Limitation by Oscillation Frequency Detuning

    Directory of Open Access Journals (Sweden)

    I. I. Serguey

    2009-01-01

    Full Text Available A numerical method has been developed for calculation of conductor oscillations at the moment of galloping that takes account of pendulum  oscillation dampers in the form of eccentric loads. The method is recommended for a numerical analysis of various schemes pertaining to arrangement of horizontal pendulums in the span and their parameters including angles of their initial setting. The obtained results can be used for designing and operation of aerial power lines. 

  4. On Galateas - magnetic traps with plasma-embedded conductors

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, A I [Russian Research Centre ' Kurchatov Institute' , Moscow (Russian Federation); Savel' ev, V V [M.V. Keldysh Institute for Applied Mathematics, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-11-30

    The introduction of plasma-embedded magnetically insulated current-carrying conductors into a plasma trap magnetic system radically increases the number of possible trap designs. The present review focuses on the studies of {beta} = 1 Galateas conducted in the 1990s. Both general and design-specific Galatea properties are discussed and for a number of specific schemes analytical and numerical calculations are performed. Experimental data on a number of electrical discharge Galateas are presented. (reviews of topical problems)

  5. What is a good conductor for metamaterials or plasmonics

    Science.gov (United States)

    Soukoulis, Costas M.; Koschny, Thomas; Tassin, Philippe; Shen, Nian-Hai; Dastmalchi, Babak

    2015-04-01

    We review conducting materials like metals, conducting oxides and graphene for nanophotonic applications. We emphasize that metamaterials and plasmonic systems benefit from different conducting materials. Resonant metamaterials need conductors with small resistivity, since dissipative loss in resonant metamaterials is proportional to the real part of the resistivity of the conducting medium it contains. For plasmonic systems, one must determine the propagation length at a desired level of confinement to estimate the dissipative loss.

  6. What is a good conductor for metamaterials or plasmonics

    Directory of Open Access Journals (Sweden)

    Soukoulis Costas M.

    2015-04-01

    Full Text Available We review conducting materials like metals, conducting oxides and graphene for nanophotonic applications. We emphasize that metamaterials and plasmonic systems benefit from different conducting materials. Resonant metamaterials need conductors with small resistivity, since dissipative loss in resonant metamaterials is proportional to the real part of the resistivity of the conducting medium it contains. For plasmonic systems, one must determine the propagation length at a desired level of confinement to estimate the dissipative loss.

  7. Non-equilibrium and band tailing in organic conductors

    Indian Academy of Sciences (India)

    A T Oza; P C Vinodkumar; R G Patel

    2003-03-01

    The concept of band tailing with focal point and width of the tail from IR absorption spectra of different organic conductors is found valid even for thermal and elastic changes. The experimental situations like change of solvents, method of preparation, applied pressure and pressure cycle apart from compositions is analyzed within the framework of tailing of states. Non-equilibrium due to coupling between applied energy and free electrons can be responsible for the exponential relaxation from non-equilibrium to equilibrium.

  8. An Organic Mixed Ion-Electron Conductor for Power Electronics.

    Science.gov (United States)

    Malti, Abdellah; Edberg, Jesper; Granberg, Hjalmar; Khan, Zia Ullah; Andreasen, Jens W; Liu, Xianjie; Zhao, Dan; Zhang, Hao; Yao, Yulong; Brill, Joseph W; Engquist, Isak; Fahlman, Mats; Wågberg, Lars; Crispin, Xavier; Berggren, Magnus

    2016-02-01

    A mixed ionic-electronic conductor based on nanofibrillated cellulose composited with poly(3,4-ethylene-dioxythio-phene):-poly(styrene-sulfonate) along with high boiling point solvents is demonstrated in bulky electrochemical devices. The high electronic and ionic conductivities of the resulting nanopaper are exploited in devices which exhibit record values for the charge storage capacitance (1F) in supercapacitors and transconductance (1S) in electrochemical transistors.

  9. Stable Delay of Microstrip Line with Side Grounded Conductors

    Directory of Open Access Journals (Sweden)

    T. R. Gazizov

    2017-01-01

    Full Text Available Characteristics of transmission lines are addressed. Wave impedance and per-unit-length delay of the microstrip structure with grounded side conductors on three layers are calculated under different parameters of the structure. A line which provides the desired value of wave impedance and constant per-unit-length delay, at the expense of correction of the gaps on different layers, is proposed.

  10. Charge densities and charge noise in mesoscopic conductors

    Indian Academy of Sciences (India)

    M Büttiker

    2002-02-01

    We introduce a hierarchy of density of states to characterize the charge distribution in a mesoscopic conductor. At the bottom of this hierarchy are the partial density of states which represent the contribution to the local density of states if both the incident and the out-going scattering channel is prescribed. The partial density of states play a prominent role in measurements with a scanning tunneling microscope on multiprobe conductors in the presence of current flow. The partial density of states determine the degree of dephasing generated by a weakly coupled voltage probe. In addition the partial density of states determine the frequency-dependent response of mesoscopic conductors in the presence of slowly oscillating voltages applied to the contacts of the sample. The partial density of states permit the formulation of a Friedel sum rule which can be applied locally. We introduce the off-diagonal elements of the partial density of states matrix to describe charge fluctuation processes. This generalization leads to a local Wigner–Smith life-time matrix.

  11. Development of an aluminium stabilized reinforced superconducting conductor

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, D. [PTR Praezisionstechnik GmbH Maintal (Germany); Horvath, I.L. [Swiss Federal Inst. of Tech., Zuerich (Switzerland); Harzenmoser, M.; Neuenschwander, J. [Swiss Federal Labs. for Materials Testing and Research, Duebendorf (Switzerland); Wittgenstein, F. [CERN, Geneva (Switzerland)

    1996-07-01

    For high performance superconducting magnets as used in large detectors for the High Energy Physics or for magnets of magnetic storage devices (SMES) the mechanical stresses on the conductor go beyond the yield stress level of the high purity matrix stabilizer, specially if aluminium is used. Therefore, a novel method is proposed to join high strength aluminium strips to high purity aluminium stabilizer by using the electron beam (EB) welding. The proposed EB-welding, combined with roll-pressing under vacuum, provides the minimum heat input on the conductor in comparison with other welding techniques. This method provides the advantage to allow the production of very long conductor lengths and includes the potentiality of repairing without losing expensive material. As this process has to be adapted to the high purity aluminium on the one side and to the high strength material on the other, the authors started in a first step with investigation and development of the process, using standard laboratory machines together with laboratory-size tooling. In this report the development program is described and first results of the quality control measurements are presented.

  12. High-field thermal transports properties of REBCO coated conductors

    CERN Document Server

    Bonura, M

    2015-01-01

    The use of REBCO coated conductors is envisaged for many applications, extending from power cables to high-field magnets. Whatever the case, thermal properties of REBCO tapes play a key role for the stability of superconducting devices. In this work, we present the first study on the longitudinal thermal conductivity (k) of REBCO coated conductors in magnetic fields up to 19 T applied both parallelly and perpendicularly to the thermal-current direction. Copper-stabilized tapes from six industrial manufacturers have been investigated. We show that zero-field k of coated conductors can be calculated with an accuracy of ‡ 15% from the residual resistivity ratio of the stabilizer and the Cu/non-Cu ratio. Measurements performed at high fields have allowed us to evaluate the consistency of the procedures generally used for estimating in-field k in the framework of the Wiedemann-Franz law from an electrical characterization of the materials. In-field data are intended to provide primary ingredients for the ...

  13. The winding line for the CMS reinforced conductor

    CERN Document Server

    Fabbricatore, P; D'Urzo, C; Farinon, S; Gaddi, A; Levesy, B; Loche, L; Musenich, R; Rondeaux, F; Penco, R; Valle, N

    2002-01-01

    The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4 T, the length is 12.5 m and the free bore is 6 m. The use of a reinforced conductor for the CMS coil required a sustained activity of development at industrial level, to understand how to handle, to pre-bend and to wind the conductor with an inner winding technique. The winding line was designed and constructed according to this experience. The working principles of the line are under test through the winding of a prototype of a CMS coil module. The prototype has the same radius of a CMS module (6900 mm outer diameter), but a shorter axial length (670 mm against 2500 for the module). The critical operations are related to the accurate pre-bending of the conductor, the positioning of the turns into the winding, the axial compaction, and the correct handling of 50-ton windings. (9 refs).

  14. Nexans advances in all CSD route for REBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Bock, J.; Ehrenberg, J.; Hoppe, B.; Isfort, D.; Klein, M.; Rikel, M. [Nexans SuperConductors, Chemiepark Knapsack, Huerth (Germany)

    2007-07-01

    Development of REBCO coated conductors (CC) at Nexans SuperConductors (NSC) is focused on all chemical solution deposition (CSD) route that promises the best performance-to-price ratio in long lengths. The feasibility of all CSD approach is shown on the lab scale: using metalorganic deposition (MOD), NSC was able to produce YBCO/CeO{sub 2}/LZO/NiW CCs with J{sub c}(77 K,sf)=0.5 MA/cm{sup 2}. The major advance of NSC on a semi-industrial scale is the use of MOD route for production of high-quality La{sub 2}Zr{sub 2}O{sub 7} (LZO) coated NiW RABITS in lengths up to 12 m. With those substrates, it is possible to produce CCs with the simplest (one-buffer) architecture by depositing REBCO using other techniques (ISD at Theva, Ismaning; MOCVD at IOT, Braunschweig; HLPE at University of Cambridge, UK). The best short sample I{sub c}=280, 120 and 100 A/cm-width for HLPE, ISD, and MOCVD, respectively First long-length conductors show transport I{sub c}=40 A (10m-long, ISD). Further work is focused on optimisation of the already established mixed (MOD+PVD) approaches, understanding optimum architecture and processing conditions for the all-CSD route and developing tools for scaling those conditions to long-length production. (orig.)

  15. Stability measurements on the 50 kA SMES conductor

    Science.gov (United States)

    Pfotenhauer, M. J.

    Stability measurements have been made on a large aluminium stabilized conductor designed for use in a superconducting magnetic energy storage (SMES) coil. The conductor has been built to carry 50 kA at 1.8 K and in 4.6 T field. It consists of a 25.4 mm diameter, high purity aluminium stabilizer with eight superconducting strands of 2.8 mm diameter each, composed of 60% Cu, 40% NbTi. The strands are set in eight helical grooves, evenly spaced around the outer diameter of the aluminium. The conductor is designed for use in full scale SMES units and has been tested in the 1 m diameter, three-turn test coil of the University of Wisconsin proof of principle experiment (POPE). The POPE facility includes the test coil, a 4 T background magnet, a dewar for a 1.8 K, 1 atm environment and a 100 kA d.c. power supply. Test results demonstrate good agreement with a new dynamic stability model. The balance of time-dependent heat generation during current diffusion and time-dependent cooling to the helium produces three new features of stability: 1, a threshold current for propagation; 2, large propagation velocities; and 3, a finite length travelling normal zone. POPE measurements verify all three features of the dynamic stability model.

  16. Conductors for commercial MRI magnets beyond NbTi: requirements and challenges

    Science.gov (United States)

    Parizh, Michael; Lvovsky, Yuri; Sumption, Michael

    2017-01-01

    Magnetic resonance imaging (MRI), a powerful medical diagnostic tool, is the largest commercial application of superconductivity. The superconducting magnet is the largest and most expensive component of an MRI system. The magnet configuration is determined by competing requirements including optimized functional performance, patient comfort, ease of siting in a hospital environment, minimum acquisition and lifecycle cost including service. In this paper, we analyze conductor requirements for commercial MRI magnets beyond traditional NbTi conductors, while avoiding links to a particular magnet configuration or design decisions. Potential conductor candidates include MgB2, ReBCO and BSCCO options. The analysis shows that no MRI-ready non-NbTi conductor is commercially available at the moment. For some conductors, MRI specifications will be difficult to achieve in principle. For others, cost is a key barrier. In some cases, the prospects for developing an MRI-ready conductor are more favorable, but significant developments are still needed. The key needs include the development of, or significant improvements in: (a) conductors specifically designed for MRI applications, with form-fit-and-function readily integratable into the present MRI magnet technology with minimum modifications. Preferably, similar conductors should be available from multiple vendors; (b) conductors with improved quench characteristics, i.e. the ability to carry significant current without damage while in the resistive state; (c) insulation which is compatible with manufacturing and refrigeration technologies; (d) dramatic increases in production and long-length quality control, including large-volume conductor manufacturing technology. In-situ MgB2 is, perhaps, the closest to meeting commercial and technical requirements to become suitable for commercial MRI. Conductor technology is an important, but not the only, issue in introduction of HTS/MgB2 conductor into commercial MRI magnets. These

  17. Exploring the limits of a very large Nb{sub 3}Sn conductor: the 80 kA conductor of the ITER toroidal field model coil

    Energy Technology Data Exchange (ETDEWEB)

    Duchateau, J.L.; Ciazynski, D.; Guerber, O.; Park, S.H.; Zani, L. [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Fietz, W.H.; Ulbricht, A.; Zahn, G. [Association Euratom-FZK Forschungszentrum, Karlsruhe (Germany)

    2003-07-01

    In Phase II experiment of the International Thermonuclear Experimental Reactor (ITER) Toroidal Field Model Coil (TFMC) the operation limits of its 80 kA Nb{sub 3}Sn conductor were explored. To increase the magnetic field on the conductor, the TFMC was tested in presence of another large coil: the EURATOM-LCT coil. Under these conditions the maximum field reached on the conductor, was around 10 tesla. This exploration has been performed at constant current, by progressively increasing the coil temperature and monitoring the coil voltage drop in the current sharing regime. Such an operation was made possible thanks to the very high stability of the conductor. The aim of these tests was to compare the critical properties of the conductor with expectations and assess the ITER TF conductor design. These expectations are based on the documented critical field and temperature dependent properties of the 720 superconducting strands which compose the conductor. In addition the conductor properties are highly dependent on the strain, due to the compression appearing on Nb{sub 3}Sn during the heat treatment of the pancakes and related to the differential thermal compression between Nb{sub 3}Sn and the stainless steel jacket. No precise model exists to predict this strain, which is therefore the main information, which is expected from these tests. The method to deduce this strain from the different tests is presented, including a thermalhydraulic analysis to identify the temperature of the critical point and a careful estimation of the field map across the conductor. The measured strain has been estimated in the range -0.75% to -0.79 %. This information will be taken into account for ITER design and some adjustment of the ITER conductor design is under examination. (authors)

  18. A Boundary Element Solution to the Problem of Interacting AC Fields in Parallel Conductors

    Directory of Open Access Journals (Sweden)

    Einar M. Rønquist

    1984-04-01

    Full Text Available The ac fields in electrically insulated conductors will interact through the surrounding electromagnetic fields. The pertinent field equations reduce to the Helmholtz equation inside each conductor (interior problem, and to the Laplace equation outside the conductors (exterior problem. These equations are transformed to integral equations, with the magnetic vector potential and its normal derivative on the boundaries as unknowns. The integral equations are then approximated by sets of algebraic equations. The interior problem involves only unknowns on the boundary of each conductor, while the exterior problem couples unknowns from several conductors. The interior and the exterior problem are coupled through the field continuity conditions. The full set of equations is solved by standard Gaussian elimination. We also show how the total current and the dissipated power within each conductor can be expressed as boundary integrals. Finally, computational results for a sample problem are compared with a finite difference solution.

  19. Conductor and joint test results of JT-60SA CS and EF coils using the NIFS test facility

    Science.gov (United States)

    Obana, Tetsuhiro; Takahata, Kazuya; Hamaguchi, Shinji; Kizu, Kaname; Murakami, Haruyuki; Chikaraishi, Hirotaka; Noguchi, Hiroki; Kobuchi, Takashi; Moriuchi, Sadatomo; Imagawa, Shinsaku; Mito, Toshiyuki; Tsuchiya, Katsuhiko; Natsume, Kyohei; Yoshida, Kiyoshi; Nomoto, Kazuhiro; Kim, Tae-hyun

    2016-01-01

    In 2007, JAEA and NIFS launched the test project to evaluate the performance of cable-in-conduit (CIC) conductors and conductor joints for the JT-60SA CS and EF coils. In this project, conductor tests for four types of coil conductor and joint tests for seven types of conductor joint have been conducted for the past eight years using the NIFS test facility. As a result, the test project indicated that the CIC conductors and conductor joints fulfill the design requirement for the CS and EF coils. In addition, the NIFS test facility is expected to be utilized as the test facility for the development of a conductor and conductor joint for the purpose of the DEMO nuclear fusion power plant, provided that the required magnetic field strength is within 9 T.

  20. Loss and Inductance Investigations in a 4-layer Superconducting Prototype Cable Conductor

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Olsen, Søren Krüger; Kühle (fratrådt), Anders Van Der Aa;

    1999-01-01

    One important issue in the design and optimization of a superconducting cable conductor is the control of the current distribution between single tapes and layers. This presentation is based on a number of experiments performed on a 4-layer three meter long prototype superconducting cable conductor......-losses are measured as a function of transport current and a given current distribution and compared with the monoblock model. Recommendations for design of future cable conductor prototypes are given....

  1. Scattering by a perfect electromagnetic conductor (PEMC) plate embedded in lossy medium

    Science.gov (United States)

    Ahmed, Saeed; Khalid Khan, Muhammad; Rehman, Atta Ur

    2016-07-01

    In this article, we develop an analytic theory for a perfect electromagnetic conductor (PEMC) plate embedded in lossy medium. The duality transformation introduced by Lindell and Sihvola is applied to study the electromagnetic wave scattering by a PEMC plate. Perfect electric conductor and perfect magnetic conductor are the limiting cases of PEMC media. Here, we study monoscattering by PEMC plate embedded in four different soil models. Numerical results are discussed and compared with the available literature.

  2. A comparison of graphene, superconductors and metals as conductors for metamaterials and plasmonics

    OpenAIRE

    Tassin, Philippe; Koschny, Thomas; Kafesaki, Maria; Soukoulis, Costas M.

    2012-01-01

    Recent advancements in metamaterials and plasmonics have promised a number of exciting applications, in particular at terahertz and optical frequencies. Unfortunately, the noble metals used in these photonic structures are not particularly good conductors at high frequencies, resulting in significant dissipative loss. Here, we address the question of what is a good conductor for metamaterials and plasmonics. For resonant metamaterials, we develop a figure-of-merit for conductors that allows f...

  3. Critical Current in YBCO Coated Conductors in the Presence of a Macroscopic Defect (POSTPRINT)

    Science.gov (United States)

    2010-03-01

    AFRL-RZ-WP-TP-2010-2084 CRITICAL CURRENT IN YBCO COATED CONDUCTORS IN THE PRESENCE OF A MACROSCOPIC DEFECT (POSTPRINT) Milan Polak and...CRITICAL CURRENT IN YBCO COATED CONDUCTORS IN THE PRESENCE OF A MACROSCOPIC DEFECT (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c...display, or disclose the work. 14. ABSTRACT We have studied the effects of localized defects in the YBCO coated conductors on the critical current. The

  4. 特殊导线的应用比较%Application Comparison of Special Conductor

    Institute of Scientific and Technical Information of China (English)

    姚洪林

    2012-01-01

    This article compares 500mm2 Section of ACCC,Gap type conductor and plain conductor suppose increase the capacity of the conductors. And Chose the suitable type of conductor based on the comparison.%本文假设导线达到倍容目的,针对截面是500mm2碳纤维导线、间隙型导线、普通导线进行比较,确定特殊导线的选择.

  5. Study on galloping behavior of iced eight bundle conductor transmission lines

    Science.gov (United States)

    Zhou, Linshu; Yan, Bo; Zhang, Liang; Zhou, Song

    2016-02-01

    Wind tunnel test was carried out to obtain the aerodynamic coefficients of an eight bundle conductor accreted with crescent-shaped ice. A user-defined cable element with torsional degree of freedom is developed in ABAQUS software to capture the torsional deformation of the iced conductors during galloping. By means of the user-defined cable element, different damping ratios in in-plane, out-of-plane and torsional directions of the conductors can be defined and the aerodynamic forces varying with their motion status can be exerted on the conductors conveniently when ABAQUS is used to simulate galloping of transmission lines. A wind tunnel test to model galloping of an iced eight bundle conductor segment was carried out, and the validity of the numerical simulation method is demonstrated by the agreement of the galloping orbit of the bundle conductor segment model recorded in the test and that by the numerical simulation. Furthermore, galloping behavior, including dynamic responses, galloping orbits, frequencies, vibration modes and amplitudes, of typical iced eight bundle conductor transmission lines in the cases of different span lengths, initial tensions in sub-conductors, wind velocities, angles of wind attack and damping ratios is studied, and the galloping behavior of the lines with internal resonance conditions is discussed. The obtained results may provide a fundamental tool for the development of anti-galloping techniques of eight bundle conductor transmission lines.

  6. Calculation of the surface effect in the ferromagnetic conductor with the harmonic electromagnetic field

    Science.gov (United States)

    Nosov, G. V.; Kuleshova, E. O.; Vassilyeva, Yu Z.; Elizarov, A. I.

    2016-04-01

    The authors of the paper have obtained formulas for analytical calculation of the constants with the harmonic electromagnetic field, which characterize the surface layer (a skin layer) of the ferromagnetic conductors in case of heating and nonlinear magnetic properties, which can be used for practical calculation of the electromagnetic screens, rotors of the electrical machines and inductive heating installations. A nonlinear dependence of the magnetic induction on the magnetic tension of the ferromagnetic conductor is replaced by one or two linear sections. It is considered that the skin layer of the conductor has constant quantities of the specific conductivity and averaged temperature. Linear electrodynamics equations are solved for the conductive half-space. Parameters of the ferromagnetic conductor's surface layer are calculated: magnetic permeability, the thickness of the skin layer and its averaged temperature, exposure time of the electromagnetic field on the conductor with the established maximum temperature on the conductor's surface, pressure of the field on the conductor and its resistance, inductivity of the internal magnetic field in the conductor, the thermal energy capacity. The methods credibility is confirmed with the concurrence of the resistance and inductiviry of the ferromagnetic conductor with analogous quantities from other methods.

  7. Keeping an eye on the conductor: neural correlates of visuo-motor synchronization and musical experience.

    Science.gov (United States)

    Ono, Kentaro; Nakamura, Akinori; Maess, Burkhard

    2015-01-01

    For orchestra musicians, synchronized playing under a conductor's direction is necessary to achieve optimal performance. Previous studies using simple auditory/visual stimuli have reported cortico-subcortical networks underlying synchronization and that training improves the accuracy of synchronization. However, it is unclear whether people who played regularly under a conductor and non-musicians activate the same networks when synchronizing with a conductor's gestures. We conducted a functional magnetic resonance imaging (fMRI) experiment testing nonmusicians and musicians who regularly play music under a conductor. Participants were required to tap the rhythm they perceived from silent movies displaying either conductor's gestures or a swinging metronome. Musicians performed tapping under a conductor with more precision than nonmusicians. Results from fMRI measurement showed greater activity in the anterior part of the left superior frontal gyrus (SFG) in musicians with more frequent practice under a conductor. Conversely, tapping with the metronome did not show any difference between musicians and nonmusicians, indicating that the expertize effect in tapping under the conductor does not result in a general increase in tapping performance for musicians. These results suggest that orchestra musicians have developed an advanced ability to predict conductor's next action from the gestures.

  8. Improving Students' Conceptual Understanding of Conductors and Insulators

    CERN Document Server

    Bilak, Joshua

    2016-01-01

    We examine the difficulties that introductory physics students, undergraduate physics majors, and physics graduate students have with concepts related to conductors and insulators covered in introductory physics by giving written tests and interviewing a subset of students. We find that even graduate students have serious difficulties with these concepts. We develop tutorials related to these topics and evaluate their effectiveness by comparing the performance on written pre-/post-tests and interviews of students who received traditional instruction vs. those who learned using tutorials.

  9. Perovskite solar cells with CuI inorganic hole conductor

    Science.gov (United States)

    Takahashi, Kenta; Suzuki, Yoshikazu

    2017-08-01

    An organic material, 2,2‧,7,7‧-tetrakis(N,N-di-p-methoxyphenylamine)9,9‧-spirobifluorene (spiro-OMeTAD), is generally used as a hole conductor of perovskite solar cells (PSCs), but spiro-OMeTAD is much more expensive than other materials used in PSCs. In this study, we have prepared PSCs with a cost-effective CuI hole transport layer by spin coating. The merit of using spin coating for CuI is good compatibility with other steps, such as spin coating of a TiO2 electron transport layer and a perovskite active layer. The CuI-based PSC recorded power conversion efficiencies of η = 2.22% (max) on the day of production and η = 6.52% (max) after the 20 days of production. Moreover, the CuI-based PSC had a smaller hysteresis than the spiro-based PSC, suggesting that CuI is a highly promising alternative hole conductor for PSCs.

  10. Solution-solid-solid mechanism: superionic conductors catalyze nanowire growth.

    Science.gov (United States)

    Wang, Junli; Chen, Kangmin; Gong, Ming; Xu, Bin; Yang, Qing

    2013-09-11

    The catalytic mechanism offers an efficient tool to produce crystalline semiconductor nanowires, in which the choice, state, and structure of catalysts are active research issues of much interest. Here we report a novel solution-solid-solid (SSS) mechanism for nanowire growth catalyzed by solid-phase superionic conductor nanocrystals in low-temperature solution. The preparation of Ag2Se-catalyzed ZnSe nanowires at 100-210 °C is exampled to elucidate the SSS model, which can be extendable to grow other II-VI semiconductor (e.g., CdSe, ZnS, and CdS) nanowires by the catalysis of nanoscale superionic-phase silver or copper(I) chalcogenides (Ag2Se, Ag2S, and Cu2S). The exceptional catalytic ability of these superionic conductors originates from their structure characteristics, known for high-density vacancies and fast mobility of silver or copper(I) cations in the rigid sublattice of Se(2-) or S(2-) ions. Insights into the SSS mechanism are provided based on the formation of solid solution and the solid-state ion diffusion/transport at solid-solid interface between catalyst and nanowire.

  11. Development of Jacketing Technologies for Iter CS and TF Conductor

    Science.gov (United States)

    Hamada, K.; Nakajima, H.; Matsui, K.; Kawano, K.; Takano, K.; Tsutsumi, F.; Okuno, K.; Teshima, O.; Soejima, K.

    2008-03-01

    The Japan Atomic Energy Agency (JAEA) has developed jacketing technologies for ITER Toroidal Field (TF) and Central Solenoid (CS) conductor. Full scale TF and CS conduits were fabricated using carbon-reduced SUS316LN and boron-added (˜40 ppm) high manganese stainless steel (0.025C -22Mn -13Cr -9Ni -0.12N: JK2LB), respectively. Welding condition was optimized so that back bead does not interfere a cable insertion. The weld joint samples were compacted by a compaction machine that was newly constructed and tested at 4.2 K. Mechanical characteristics at 4K of CS, TF conduits and CS welded joint satisfied ITER mechanical requirements. TF welded joint shows slightly lower value of 0.2% yield strength (885 MPa) than that of ITER requirement (900 MPa). The TF conduit contains nitrogen content of 0.14%, which is minimum value in ITER specification. The lower nitrogen content may be caused by the release of nitrogen from molten metal during non-filler welding resulting in a 4 K strength decrease. To satisfy the ITER requirements, minimum nitrogen contents of conduit should be increased from 0.14% to 0.15% at least. Therefore, JAEA successfully developed TF and CS conduits with welding technologies and finalized the procurement specification for ITER conductor jacketing.

  12. Strong light-field effects in correlated oraganic conductors

    Science.gov (United States)

    Iwai, Shinichiro; Kawakami, Yohei; Naitoh, Yota; Itoh, Hirotake; Ishihara, Sumio; Yonemitsu, Kenji

    Optical responses of organic conductors have attracted much attentions, because they exhibit ultrafast solid-state phase transitions in the conducting and/or dielectric natures upon photo-excitations. In this decade, photoinduced melting of correlated insulators with clear charge gap have been extensively investigated. On the other hand, optical rsponses of correlated metal has not been studied well. Here, we describe a charge localization induced by the 9.3 MV/cm instantaneous electric field of a 1.5 cycle (7 fs) infrared pulse in an organic conductor alpha- (bis[ethylenedithio]-tetrathiafulvelene)2I3. A large reflectivity change of 30 percent and a coherent charge oscillation along the time axis reflect the opening of the charge ordering gap in the metallic phase. This optical freezing of charges, which is the reverse of the photoinduced melting of electronic orders, is attributed to the 10 percent reduction of t driven by the strong, high-frequency electric field. Furthermore, the contribution of Coulomb repulsion will be discussed on the basis of the polarization dependence of the pump light and the theory.

  13. A Na+ Superionic Conductor for Room-Temperature Sodium Batteries

    Science.gov (United States)

    Song, Shufeng; Duong, Hai M.; Korsunsky, Alexander M.; Hu, Ning; Lu, Li

    2016-08-01

    Rechargeable lithium ion batteries have ruled the consumer electronics market for the past 20 years and have great significance in the growing number of electric vehicles and stationary energy storage applications. However, in addition to concerns about electrochemical performance, the limited availability of lithium is gradually becoming an important issue for further continued use and development of lithium ion batteries. Therefore, a significant shift in attention has been taking place towards new types of rechargeable batteries such as sodium-based systems that have low cost. Another important aspect of sodium battery is its potential compatibility with the all-solid-state design where solid electrolyte is used to replace liquid one, leading to simple battery design, long life span, and excellent safety. The key to the success of all-solid-state battery design is the challenge of finding solid electrolytes possessing acceptable high ionic conductivities at room temperature. Herein, we report a novel sodium superionic conductor with NASICON structure, Na3.1Zr1.95Mg0.05Si2PO12 that shows high room-temperature ionic conductivity of 3.5 × 10‑3 S cm‑1. We also report successful fabrication of a room-temperature solid-state Na-S cell using this conductor.

  14. Mutual capacitance of liquid conductors in deformable tactile sensing arrays

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bin [Electrical and Computer Engineering Department, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Fontecchio, Adam K. [Electrical and Computer Engineering and Materials Science and Engineering Departments, Drexel University, Philadelphia, Pennsylvania 19104 (United States); Visell, Yon [Electrical and Computer Engineering Department, Media Arts and Technology, California NanoSystems Institute, University of California, Santa Barbara, California 93106 (United States)

    2016-01-04

    Advances in highly deformable electronics are needed in order to enable emerging categories of soft computing devices ranging from wearable electronics, to medical devices, and soft robotic components. The combination of highly elastic substrates with intrinsically stretchable conductors holds the promise of enabling electronic sensors that can conform to curved objects, reconfigurable displays, or soft biological tissues, including the skin. Here, we contribute sensing principles for tactile (mechanical image) sensors based on very low modulus polymer substrates with embedded liquid metal microfluidic arrays. The sensors are fabricated using a single-step casting method that utilizes fine nylon filaments to produce arrays of cylindrical channels on two layers. The liquid metal (gallium indium alloy) conductors that fill these channels readily adopt the shape of the embedding membrane, yielding levels of deformability greater than 400%, due to the use of soft polymer substrates. We modeled the sensor performance using electrostatic theory and continuum mechanics, yielding excellent agreement with experiments. Using a matrix-addressed capacitance measurement technique, we are able to resolve strain distributions with millimeter resolution over areas of several square centimeters.

  15. IBAD-MgO technology for coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Jo, William [Dept. of Physics, Ewha Womans University, Seoul (Korea, Republic of)

    2016-09-15

    Ion-beam assisted deposition (IBAD) technology has been successfully applied to high-temperature superconductor coated conductors (CC) as textured substrates. Since the coated conductors were proposed as a potential framework for utilizing the superior transport characteristics of YBa2Cu3O7 and related cuprate oxides, several methods including rolling-assisted bi-axial textured substrates (RABiTS) and inclined substrate deposition (ISD), as well as IBAD, have been attempted. As of 2016, most companies that are trying to commercialize CC adapt IBAD technology except for American Superconductors who use RABiTS predominantly. For the materials in the IBAD process, initial efforts to use yttria-stabilized zirconia (YSZ) or related fluorites in Fujikura in Japan have quickly given way to MgO which technique was developed by Stanford University in the USA. In this review, we present a historical overview of IBAD technology, in particular, for the application of CC. We describe the key scientific understanding of nucleation, the texturing mechanism, and the growth of large bi-axial grains and discuss some potential new IBAD materials and systems for large-scale production.

  16. Li mobility in fast ion conductors followed by NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, J.

    2010-07-01

    Structural features that enhance Li mobility in fast ion conductors with perovskite (Li{sub 3}xLa{sub 2}/3-xTiO{sub 3} series) and Nasicon structure (Li{sub 1}+xTi{sub 2}-xAl{sub x} (PO{sub 4}){sub 3} series) have been investigated. From the analysis of quadrupolar interactions, the local symmetry and exchange processes between structural sites occupied by lithium have been deduced to investigate local motions of lithium in conduction paths of analyzed compounds. The study of spin-lattice (T{sub 1}) and spin-spin (T{sub 2}) relaxation times made possible the analysis of the temperature dependence of Li residence times at structural sites. The comparison of these values with those deduced from conductivity (ac and dc-measurements) allowed the study of Li-motion mechanisms. The onset of long range motions requires the analysis of low frequency measurements (T{sub 2} relaxation and dc-conductivity). The non- Arrhenius behaviour, often observed in fast ion conductors, has been ascribed to order/disorder transitions. At increasing temperatures, Li motions become less correlated, producing the decrement of activation energy. In analyzed compounds, a direct measurement of diffusion coefficients has been obtained from NMR experiments performed with the pulse field gradient (PFG) technique. Finally, it is emphasized the importance of the vacancy percolation in conductivity processes. (Author)

  17. Broadband dielectric spectroscopy of inhomogeneous and composite weak conductors

    Science.gov (United States)

    Petzelt, J.; Nuzhnyy, D.

    2016-08-01

    In this paper, we discuss broadband dielectric spectroscopy from mHz up to the infrared range mainly for materials with inhomogeneous weak conductivity, including conductor-dielectric nanocomposites. Our discussion is based on the effective medium approximation (EMA) and experiments modeled by this approach are reviewed. We discuss core-shell composites modeled by coated-spheres (Hashin-Shtrikman model) and normal composites with a possible percolation of the conductor component resulting in sharp or smeared percolation threshold of the DC conductivity and diverging static permittivity in the former case. The sharp percolation threshold is modeled by the Bruggeman EMA or by general EMA with arbitrary percolation threshold and arbitrary critical exponents of the DC conductivity and static permittivity. For the case of smeared percolation threshold in the case of complex topologies, we use the Lichtenecker model allowing for partial percolation of both the components. Finally, numerous papers reporting negative permittivity in weakly conducting materials are criticized and concluded to be due to spurious effects.

  18. ATLAS SemiConductor Tracker Operation and Performance

    CERN Document Server

    Tojo, J; The ATLAS collaboration

    2011-01-01

    The SemiConductor Tracker (SCT), comprising of silicon micro-strip detectors is one of the key precision tracking devices in the ATLAS Inner Detector. ATLAS is one of the experiments at CERN LHC. The completed SCT is in very good shapes with 99.3% of the SCT’s 4088 modules (a total of 6.3 million strips) are operational. The noise occupancy and hit efficiency exceed the design specifications. In the talk the current status of the SCT will be reviewed. We will report on the operation of the detector, its performance and observed problems, with stress on the sensor and electronics performance. In December 2009 the ATLAS experiment at the CERN Large Hadron Collider (LHC) recorded the first proton-proton collisions at a centre-of-mass energy of 900 GeV and this was followed by the unprecedented energy of 7 TeV in March 2010. The Semi- Conductor Tracker (SCT) is the key precision tracking device in ATLAS, made from silicon micro-strip detectors processed in the planar p-in-n technology. The signals from the stri...

  19. Amorphous carbon interlayers for gold on elastomer stretchable conductors

    Science.gov (United States)

    Manzoor, M. U.; Tuinea-Bobe, C. L.; McKavanagh, F.; Byrne, C. P.; Dixon, D.; Maguire, P. D.; Lemoine, P.

    2011-06-01

    Gold on polydimethylsiloxane (PDMS) stretchable conductors were prepared using a novel approach by interlacing an hydrogenated amorphous carbon (a-C : H) layer between the deposited metal layer and the elastomer. AFM analysis of the a-C : H film surface before gold deposition shows nanoscale buckling, the corresponding increase in specific surface area corresponds to a strain compensation for the first 4-6% of bi-axial tensile loading. Without this interlayer, the deposited gold films show much smaller and uni-directional ripples as well as more cracks and delaminations. With a-C : H interlayer, the initial electrical resistivity of the metal film decreases markedly (280-fold decrease to 8 × 10-6 Ω cm). This is not due to conduction within the carbon interlayer; both a-C : H/PDMS and PDMS substrates are electrically insulating. Upon cyclic tensile loading, both films become more resistive, but return to their initial state after 20 tensile cycles up to 60% strain. Profiling experiments using secondary ion mass spectroscopy and x-ray photoelectron spectroscopy indicate that the a-C : H layer intermixes with the PDMS, resulting in a graded layer of decreasing stiffness. We believe that both this graded layer and the surface buckling contribute to the observed improvement in the electrical performance of these stretchable conductors.

  20. The Optical Links of the ATLAS SemiConductor Tracker

    CERN Document Server

    Abdesselam, A; Apsimon, R; Band, C; Barr, C; Batchelor, L; Bates, R; Bell, P; Bernabeu, J; Bizzell, J; Brenner, R; Brodbeck, T; Bruckman De Renstrom, P; Buttar, C; Carter, J; Charlton, D; Cheplakov, A; Chilingarov, A; Chu, M-L; Colijn, A-P; Dawson, I; Demirkõz, B; de Jong, P; Dervan, P; Dolezal, Z; Dowell, J; Escobar, P; Spencer, E; Ekelöf, T J C; Eklund, L; Ferrere, D; Fraser, T; French, M; French, R; Fuster, J; Gallop, B; García, C; Goodrick, M; Greenall, A; Grillo, A; Grosse-Knetter, J; Hartjes, F; Hessey, N; Hill, J C; Homer, J; Hou, L; Hughes, G; Ikegami, Y; Issever, C; Jackson, J; Jones, M; Jones, T J; Jovanovic, P; Koffeman, E; Kodys, P; Kohriki, T; Lee, S-C; Lester, C; Limper, M; Lindsay, S W; Lozano, M; Macwaters, C; Magrath, C; Mahout, G; Mandic, I; Matheson, J; McMahon, T; Mikulec, B; Muijs, A; Morrissey, M; Nichols, A; Nickerson, R; O'Shea, V; Pagenis, S; Parker, M; Pater, J; Perrin, E; Pernegger, H; Peeters, S; Phillips, P; Postranecky, M; Robinson, D; Robson, A; Rudge, A; Sandaker, H; Sedlak, K; Smith, N A; Stapnes, S; Stugu, B; Teng, P K; Terada, S; Tricoli, A; Tyndel, M; Ujiie, N; Ullán, M; Unno, Y; van der Kraaij, E; Van Vulpen, I; Viehhauser, G; Vossebeld, J H; Warren, M; Wastie, R; Weidberg, A; Wells, P; White, D; Wilson, J

    2007-01-01

    Optical links are used for the readout of the 4088 silicon microstrip modules that make up the SemiConductor Tracker of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The optical link requirements are reviewed, with particular emphasis on the very demanding environment at the LHC. The on-detector components have to operate in high radiation levels for 10 years, with no maintenance, and there are very strict requirements on power consumption, material and space. A novel concept for the packaging of the on-detector optoelectronics has been developed to meet these requirements. The system architecture, including its redundancy features, is explained and the critical on-detector components are described. The results of the extensive Quality Assurance performed during all steps of the assembly are discussed. Optical links are used for the readout of the 4088 silicon microstrip modules that make up the SemiConductor Tracker of the ATLAS experiment at the CERN Large Hadron Collider (LHC). The optical ...

  1. A Na+ Superionic Conductor for Room-Temperature Sodium Batteries

    Science.gov (United States)

    Song, Shufeng; Duong, Hai M.; Korsunsky, Alexander M.; Hu, Ning; Lu, Li

    2016-01-01

    Rechargeable lithium ion batteries have ruled the consumer electronics market for the past 20 years and have great significance in the growing number of electric vehicles and stationary energy storage applications. However, in addition to concerns about electrochemical performance, the limited availability of lithium is gradually becoming an important issue for further continued use and development of lithium ion batteries. Therefore, a significant shift in attention has been taking place towards new types of rechargeable batteries such as sodium-based systems that have low cost. Another important aspect of sodium battery is its potential compatibility with the all-solid-state design where solid electrolyte is used to replace liquid one, leading to simple battery design, long life span, and excellent safety. The key to the success of all-solid-state battery design is the challenge of finding solid electrolytes possessing acceptable high ionic conductivities at room temperature. Herein, we report a novel sodium superionic conductor with NASICON structure, Na3.1Zr1.95Mg0.05Si2PO12 that shows high room-temperature ionic conductivity of 3.5 × 10−3 S cm−1. We also report successful fabrication of a room-temperature solid-state Na-S cell using this conductor. PMID:27572915

  2. High-voltage transmission conductor motion research. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rawlins, C.B.

    1976-06-01

    Research on wake-induced oscillation of bundled conductors performed to develop the technoogy required for design of bundle lines and for alteration of existing lines to prevent the oscillations is described. The investigation to date has encompassed a program of measurements of oscillation behavior of existing lines, measurements of turbulence of natural winds to which the lines are exposed, wind tunnel measurements of aerodynamic characteristics of conductors in bundles, and development of theoretical and computer analyses for predicting conditions under which actual spans may oscillate. The computer analyses used with the wind tunnel data developed in the program, provide a useful tool for predicting the effectiveness of devices and procedures intended to prevent oscillation. The influence of local terrain is taken into account. Comparison of predictions based on the computer analyses with measured behavior of actual field spans is satisfactory in the cases where comparison is possible. The number of such cases is limited by the range of the wind tunnel data that must be used with the computer analyses. Continuation of the program to expand the range of wind tunnel data, and to broaden the array of field test data to permit more thorough validation of the analyses, is recommended.

  3. Nb3Sn Conductor Development and Characterization for NED

    CERN Document Server

    Boutboul, T; Devred, A; Fabbricatore, P; Greco, M; Leroy, D; Oberli, L; Pedrini, D; Volpini, G

    2008-01-01

    The main purpose of Next European Dipole (NED) project is to design and to build an Nb3Sn ~ 15 T dipole magnet. Due to budget constraints, NED is mainly focused on superconducting cable development and production. In this work, an update is given on the NED conductor development by Alstom-MSA and SMI, which uses, respectively, Internal-Tin-Diffusion and Powder-In-Tube methods, with the aim of reaching a non-copper critical current density of ~ 3000 A/mm2 at 12 T and 4.2 K. Characterization results, including critical current and magnetization data, are presented and discussed, as well, for conductors already developed by both companies for this project. SMI succeeded to produce a strand with 50 µm diameter filaments and with a critical current of ~ 1400 A at 4.2 K and 12 T, corresponding to a non-copper critical current density of ~ 2500 A/mm2. Cabling trials with this strand were successfully carried out at LBNL.

  4. Quenched microemulsions: a new route to proton conductors.

    Science.gov (United States)

    Noirjean, Cecile; Testard, Fabienne; Jestin, Jacques; Taché, Olivier; Dejugnat, Christophe; Carriere, David

    2014-08-28

    Solid-state proton conductors operating under mild temperature conditions (T < 150 °C) would promote the use of electrochemical devices as fuel cells. Alternatives to the water-sensitive membranes made of perfluorinated sulfonated polymers require the use of protogenic moieties bearing phosphates/phosphonates or imidazole groups. Here, we formulate microemulsions using water, a cationic surfactant (cetyltrimethyl ammonium bromide, CTAB) and a fatty acid (myristic acid, MA). The fatty acid acts both as an oil phase above its melting point (52 °C) and as a protogenic moiety. We demonstrate that the mixed MA-CTA film presents significant proton conductivity. Furthermore, bicontinuous microemulsions are found in the water-CTAB-MA phase diagram above 52 °C, where molten MA plays both the role of the oil phase and the co-surfactant. This indicates that the hydrogen-bond rich MA-CTA film can be formulated in the molten phase. The microemulsion converts into a lamellar phase upon solidification at room temperature. Our results demonstrate the potential of such self-assembled materials for the design of bulk proton conductors, but also highlight the necessity to control the evolution of the nanostructure upon solidification of the oil phase.

  5. Effective Installations Technique of Grounding Conductors for Metal Oxide Surge Arresters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.H.; Kang, S.M. [Inha University, Inchon (Korea); Ryu, I.S. [Korea Electric Power Corporation, Seoul (Korea)

    2002-06-01

    This paper deals with the effects of grounding conductors for metal oxide surge arresters. When surge arresters are improperly installed, the results can cause costly damage of electrical equipments. In particular, the route of surge arrester connection is very important because bends and links of leads increase the impedances to lightning surges and tend to nullify the effectiveness of a grounding conductor. Therefore, there is a need to know how effective installation of lightning surge arresters is made in order to control voltage and to absorb energy at high lightning currents. The effectiveness of a grounding conductor and 18 [kV] metal oxide distribution line arresters was experimentally investigated under the lightning and oscillatory impulse voltages. Thus, the results are as follows; (1) The induced voltage of a grounding conductor is drastically not affected by length of a connecting line, but it is very sensitive to types of grounding conductor. (2) The coaxial cable having a low characteristic impedance is suitable as a grounding conductor. (3) It is also clear from these results that bonding the metal raceway enclosing the grounding conductor to the grounding electrode is very effective because of skin effect. (4) The induced voltages of grounding conductors for the oscillatory impulse voltages are approximately twice as large as those for the lightning impulse voltages. (author). 9 refs., 12 figs., 2 tabs.

  6. Powder-in-Tube (PIT) Nb3Sn conductors for high-field magnets

    NARCIS (Netherlands)

    Lindenhovius, J.H.; Hornsveld, E.M.; den Ouden, A.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.

    2000-01-01

    New Nb3Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment o

  7. Measuring ac-loss in high temperature superconducting cable-conductors using four probe methods

    DEFF Research Database (Denmark)

    Kühle (fratrådt), Anders Van Der Aa; Træholt, Chresten; Olsen, Søren Krüger;

    1999-01-01

    Measuring the ac-loss of superconducting cable conductors have many aspects in common with measuring the ac-loss of single superconducting tapes. In a cable conductor all tapes are connected to each other and to the test circuit through normal metal joints in each end. This makes such measurement...

  8. Current Density Distribution on the Perimeter of Waveguide Exciter Cylindrical Vibrator Conductor

    OpenAIRE

    Zakharia, Yosyp

    2010-01-01

    On ground of electrodynamic analysis the surface current distribution nonuniformity on the perimeter of waveguide-exciter cylindrical conductor is found. Considerable influence of current distribution nonuniformity on exciter input reactance is established. It is also showed, that the current distribution on the vibrator perimeter, for conductor radius no greater then 0,07 of waveguide cross section breadth, approximately uniform is.

  9. Testing of flat conductor cable to Underwriters Laboratory standards UL719 and UL83

    Science.gov (United States)

    Loggins, R. W.; Herndon, R. H.

    1974-01-01

    The flat conductor cable (FCC) which was tested consisted of three AWG No. 12 flat copper conductors laminated between two films of polyethylene terephthalate (Mylar) insulation with a self-extinguishing polyester adhesive. Results of the tests conducted on this cable, according to specifications, warrants the use of this FCC for electrical interconnections in a surface nonmetallic protective covering.

  10. Theoretical Investigation on Skin Effect Factor of Conductor in Power Cables

    Science.gov (United States)

    Suzuki, Hiroshi; Kanaoka, Mamoru

    This paper describes a newly-derived theoretical equation on the skin effect factor of power cables, and its application to large-size OF and XLPE cables with segmental conductors, including insulated wires. The skin effect factors calculated with the new equation were fit very well to measurements in wide range conductor sizes. In the new equation, the important factor which characterizes the skin effect of segmental conductors is the `equivalent conductivity ratio' ν defined by the ratio of longitudinal conductivity in axial direction of conductor to conductivity of conductor wires. Since the obtained ratio ν in XLPE cable was three times greater than that in OF cable, the larger longitudinal eddy current passing from a wire to another increased the eddy current loss in conductor, which increased the conductor loss of XLPE cable. The new equation enables us to investigate quantitatively the dominant loss component affecting the skin effect factor. Then, the skin effect factors and coefficients for OF and XLPE cables were investigated with the new equation. It was revealed that the best number of separation, in which the skin effect became minimum, existed in OF and XLPE cables with segmental conductors. In addition, it was confirmed that the skin effect coefficients ks1 calculated with the new equation were consistent well with those used in JCS.

  11. Powder-in-Tube (PIT) Nb3Sn conductors for high-field magnets

    NARCIS (Netherlands)

    Lindenhovius, J.H.; Hornsveld, E.M.; den Ouden, A.; Wessel, Wilhelm A.J.; ten Kate, Herman H.J.

    2000-01-01

    New Nb3Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment

  12. Transport current dependence of the hysteresis loss in silver sheathed BSCOO-2212 conductors

    NARCIS (Netherlands)

    Hemmes, Herman K.; Woudstra, Martin J.; ten Kate, Herman H.J.; Tenbrink, Johannes

    1994-01-01

    A technique is described to study the critical current density and penetration fieldassociated with the transport current in a silver sheathed BSCCO conductor. A transport current flowing in a conductor in a varying magnetic field will only influence magnetisation currents that are in competition

  13. Modelling and simulation of the ice melting process on a current-carrying conductor

    Energy Technology Data Exchange (ETDEWEB)

    Peter, Z.

    2006-07-01

    Mathematical models were developed to determine the current and energy requirements for thermal de-icing and ice prevention on overhead power transmission lines. The models were based on the Joule effect under various meteorological and current transmission conditions. The minimum current intensity required to inhibit ice formation on a single power line conductor was determined. Correction factors were then introduced for 3 specific aluminum conductors with steel reinforcement (ACSRs). Water runback on the conductor surface was considered as well as deviation of the water layer from the thermal equilibrium state. Model results were in good agreement with measurements taken in an icing research wind tunnel. The overall heat transfer coefficient (HTC) for stranded conductors was then assessed to complete the model. A computational model using finite differences was also developed to calculate the current and energy requirements for de-icing partially ice covered conductors. Joule heating by AC current and impulse current were the 2 heating techniques analyzed. Thermal conductivity of the ACSR conductor was also estimated. Experimentally validated analytical approaches were proposed to determine the shedding time and corresponding energy required to de-ice a completely ice covered conductor by heating with increased nominal AC current. It was concluded that ice accretion on a single power line can be prevented using the experimentally validated mathematical models that calculate the current and energy requirements of de-icing conductors.

  14. An experimental method to determine the electrostatic field enhancement factor of a practical conductor surface

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, George C

    1989-01-01

    A method of determining the field enhancement factor of a practical conductor is presented. The method is developed from a modified theory of discharge onset in a gaseous medium. This modification incorporates the influence of conductor surface roughness. Onset data from an experimental study tha...

  15. Thin magnetic conductor substrate for placement-immune, electrically-small antennas.

    Energy Technology Data Exchange (ETDEWEB)

    Eubanks, Travis Wayne; McDonald, Jacob J.; Loui, Hung

    2011-09-01

    An antenna is considered to be placement-immune when the antenna operates effectively regardless of where it is placed. By building antennas on magnetic conductor materials, the radiated fields will be positively reinforced in the desired radiation direction instead of being negatively affected by the environment. Although this idea has been discussed thoroughly in theoretical research, the difficulty in building thin magnetic conductor materials necessary for in-phase field reflections prevents this technology from becoming more widespread. This project's purpose is to build and measure an electrically-small antenna on a new type of non-metallic, thin magnetic conductor. This problem has not been previously addressed because non-metallic, thin magnetic conductor materials have not yet been discovered. This work proposed the creation of an artificial magnetic conductor (AMC) with in-phase field reflections without using internal electric conductors, the placement of an electrically-small antenna on this magnetic conductor, and the development of a transmit-receive system that utilizes the substrate and electrically-small antenna. By not using internal electric conductors to create the AMC, the substrate thickness can be minimized. The electrically-small antenna will demonstrate the substrate's ability to make an antenna placement immune, and the transmit-receive system combines both the antenna and the substrate while adding a third layer of system complexity to demonstrate the complete idea.

  16. Current Sharing Temperature Test and Simulation with GANDALF Code for ITER PF2 Conductor Sample

    Science.gov (United States)

    Li, Shaolei; Wu, Yu; Liu, Bo; Weng, Peide

    2011-10-01

    Cable-in-conduit conductor (CICC) conductor sample of the PF2 coil for ITER was tested in the SULTAN facility. According to the test results, the CICC conductor sample exhibited a stable performance regarding the current sharing temperature. Under the typical operational conditions of a current of 45 kA, a magnetic field of 4 T and a temperature of 5 K for PF2, the test result for the conductor current sharing temperature is 6.71 K, with a temperature margin of 1.71 K. For a comparison thermal-hydraulic analysis of the PF2 conductor was carried out using GANDALF code in a 1-D model, and the result is consistent with the test one.

  17. Current distribution and stability of LTS/HTS hybrid superconducting conductors

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Current distribution and stability of a hybrid LTS/HTS superconductor, consisting of multifilamentary NbTi/Cu and Bi2223/Ag tapes, were numerically analyzed according to power-law models. The results showed that most of current passed through the LTS and the current increased in the HTS with temperature rise when the transport current was below the critical current of the hybrid conductor. The quench propagation velocity of the hybrid conductor was smaller but its minimum quench energy was larger than those of LTS conductors, indicating that the stability of the hybrid superconducting conductor was effectively improved and a high engineering current density was simultaneously achieved. Finally, a hybrid sample, made by soldering Bi2223/Ag tape onto NbTi/Cu conductor, was prepared and tested successfully at helium temperature. The experimental results qualitatively agreed with the simulated ones.

  18. Magnetic guide of cold atoms using a U-shaped current-carrying conductor

    Institute of Scientific and Technical Information of China (English)

    刘南春; 印建平

    2003-01-01

    We propose a new scheme to magnetically guide cold neutral atoms using a U-shaped current carrying conductor.The spatial magnetic field distribution from the U-shaped current-carrying conductor and the relationship between the magnetic field and parameters of the U-shaped conductor are analysed.Our study shows that U-shaped current-carrying conductor can be used to realize single-or double-channel magnetic guiding of cold atoms in weak-field-seeking states and to construct wrious atom-optical elements.By using Monte Carlo simulations,the dynamic process of the guided atomic-beam splitting in an atomic-beam splitter composed by the U-shaped current-carrying conductor is studied,and some results are presented.

  19. Parametric analysis of hollow conductor parallel and coaxial transmission lines for high frequency space power distribution

    Science.gov (United States)

    Jeffries, K. S.; Renz, D. D.

    1984-01-01

    A parametric analysis was performed of transmission cables for transmitting electrical power at high voltage (up to 1000 V) and high frequency (10 to 30 kHz) for high power (100 kW or more) space missions. Large diameter (5 to 30 mm) hollow conductors were considered in closely spaced coaxial configurations and in parallel lines. Formulas were derived to calculate inductance and resistance for these conductors. Curves of cable conductance, mass, inductance, capacitance, resistance, power loss, and temperature were plotted for various conductor diameters, conductor thickness, and alternating current frequencies. An example 5 mm diameter coaxial cable with 0.5 mm conductor thickness was calculated to transmit 100 kW at 1000 Vac, 50 m with a power loss of 1900 W, an inductance of 1.45 micron and a capacitance of 0.07 micron-F. The computer programs written for this analysis are listed in the appendix.

  20. Nb3Sn conductor development and characterization for NED+ Nb3Sn conductor development and characterization for NED+

    Science.gov (United States)

    Boutboul, T.; den Ouden, A.; Devred, A.; Fabbricatore, P.; Greco, M.; Leroy, D.; Oberli, L.; Pedrini, D.; Volpini, G.

    2008-02-01

    The main purpose of Next European Dipole (NED) project is to design and to build an Nb3Sn ~ 15 T dipole magnet. Due to budget constraints, NED is mainly focused on superconducting cable development and production. In this work, an update is given on the NED conductor development by Alstom-MSA and SMI, which uses, respectively, Internal-Tin-Diffusion and Powder-In-Tube methods, with the aim of reaching a non-copper critical current density of ~ 3000 A/mm2 at 12 T and 4.2 K. Characterization results, including critical current and magnetization data, are presented and discussed, as well, for conductors already developed by both companies for this project. SMI succeeded to produce a strand with 50 μm diameter filaments and with a critical current of ~ 1400 A at 4.2 K and 12 T, corresponding to a non-copper critical current density of ~ 2500 A/mm2. Cabling trials with this strand were successfully carried out at LBNL.

  1. Field dependence of the critical current and its relation to the anisotropy of BSCCO conductors and coils

    NARCIS (Netherlands)

    Weijers, H.W.; Haken, ten B.; Kate, ten H.H.J.; Schwartz, J.

    2005-01-01

    The design of HTS magnets is often based on the properties of a number of short samples that are presumed to be representative of the conductor to be used. Variability in conductor properties and inhomogeneity in the magnetic field distribution within the magnets, coupled with conductor anisotropy,

  2. Non-classical radiation emission by a coherent conductor

    Science.gov (United States)

    Forgues, Jean-Charles; Gasse, Gabriel; Lupien, Christian; Reulet, Bertrand

    2016-08-01

    We report experimental evidence that the microwave electromagnetic field generated by a normal conductor, here a tunnel junction placed at ultra-low temperature, can be non-classical. By measuring the quadratures of the electromagnetic field at one or two frequencies in the GHz range, we demonstrate the existence of squeezing as well as entanglement in such radiation. In one experiment, we observe that the variance of one quadrature of the photo-assisted noise generated by the junction goes below its vacuum level. In the second experiment, we demonstrate the existence of correlations between the quadratures taken at two frequencies, which can be stronger than allowed by classical mechanics, proving that the radiation at those two frequencies are entangled. xml:lang="fr"

  3. Effect of annular secondary conductor in a linear electromagnetic stirrer

    Indian Academy of Sciences (India)

    R Madhavan; V Ramanarayanan

    2008-10-01

    This paper presents the variation of average axial force density in the annular secondary conductor of a linear electromagnetic stirrer. Different geometries of secondaries are considered for numerical and experimental validation namely, 1. hollow annular ring, 2. annular ring with a solid cylinder and 3. solid cylinder. Experimental and numerical simulations are performed for a 2-pole in house built 15 kW linear electromagnetic stirrer (EMS). It is observed for a supply current of 200 A at 30 Hz the force densities in the hollow annular ring is 67% higher than the equivalent solid cylinder. The same values are 33% for annular ring with a solid cylinder. Force density variation with supply frequency and current are also reported. Numerical simulations using finite element model are validated with experimental results.

  4. Control of flux pinning in MOD YBCO coated conductor.

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, W.; Huang, Y.; Li, X.; Kodenkandath, T.; Rupich, M. W.; Schoop, U.; Verebelyi, D. T.; Thieme, C. L. H.; Siegal, E.; Holesinger, T. G.; Maiorov, B.; Civale, L.; Miller, D. J.; Maroni, V. A.; Li, J.; Martin, P. M.; Specht, E. D.; Goyal, A.; Paranthaman, M. P.; American Superconductor Corp.; LANL; ORNL

    2007-06-01

    NTwo different types of defect structures have been identified to be responsible for the enhanced pinning in metal organic deposited YBCO films. Rare earth additions result in the formation of nanodots in the YBCO matrix, which form uncorrelated pinning centers, increasing pinning in all magnetic field orientations. 124-type intergrowths, which form as laminar structures parallel to the ab-plane, are responsible for the large current enhancement when the magnetic field is oriented in the ab-plane. TEM studies showed that the intergrowths emanate from cuprous containing secondary phase particles, whose density is partially controlled by the rare earth doping level. Critical process parameters have been identified to control this phase formation, and therefore, control the f 24 intergrowth formation. This work has shown that through process control and proper conductor design, either by adjusting the composition or by multiple coatings of different functional layers, the desired angular dependence can be achieved.

  5. Fuel-Cell Electrolytes Based on Organosilica Hybrid Proton Conductors

    Science.gov (United States)

    Narayan, Sri R.; Yen, Shiao-Pin S.

    2008-01-01

    A new membrane composite material that combines an organosilica proton conductor with perfluorinated Nafion material to achieve good proton conductivity and high-temperature performance for membranes used for fuel cells in stationary, transportation, and portable applications has been developed. To achieve high proton conductivities of the order of 10(exp -1)S/cm over a wide range of temperatures, a composite membrane based on a new class of mesoporous, proton-conducting, hydrogen-bonded organosilica, used with Nafion, will allow for water retention and high proton conductivity over a wider range of temperatures than currently offered by Nafion alone. At the time of this reporting, this innovation is at the concept level. Some of the materials and processes investigated have shown good proton conductivity, but membranes have not yet been prepared and demonstrated.

  6. A high conductivity oxide–sulfide composite lithium superionic conductor

    Energy Technology Data Exchange (ETDEWEB)

    Rangasamy, Ezhiylmurugan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Sahu, Gayatri [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Keum, Jong Kahk [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Rondinone, Adam J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science; Dudney, Nancy J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Liang, Chengdu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science

    2014-01-14

    We fabricated a hybrid superionic conductor using the space charge effect between the LLZO and LPS interfaces. This space-charge effect resulted in an improvement over the individual bulk conductivities of the two systems. Sample with higher weight fractions of LLZO are limited by the porosity and grain boundary resistance arising from non-sintered membranes. Furthermore, by combining the properties of LLZO and LPS, the high temperature sintering step has been avoided thus facilitating easier materials processing. The interfacial resistances were also measured to be minimal at ambient conditions. Our procedure thus opens a new avenue for improving the ionic conductivity and electrochemical properties of existing solid state electrolytes. High frequency impedance analyses could aid in resolving the ionic conductivity contributions from the space charge layer in the higher conducting composites while mechanical property investigations could illustrate an improvement in the composite electrolyte in comparison with the crystalline LPS membranes.

  7. Development of HTS power cable using YBCO coated conductor

    Science.gov (United States)

    Mukoyama, Shinichi; Yagi, Masashi; Hirano, Hironobu; Yamada, Yutaka; Izumi, Teruo; Shiohara, Yuh

    2006-10-01

    Reductions of AC losses and of cost of HTS power cables are important to put it into practical power networks. Since an YBCO-coated-conductor (YBCO tape) has higher Jc and better magnetic property than a Bi2223-Ag-sheathed-tape, an AC power cable using YBCO tapes will obtain higher performance than XLPE-cables and HTS cables using BSCCO tapes in future. Especially, an YBCO HTS cable will be expected to become a higher economical cable than a Bi cable because an YBCO tape reduced its AC losses and its wire cost. We have started developing HTS power cables using YBCO tapes. Mechanical properties, superconducting properties and other electro magnetic properties of YBCO tapes have been measured to estimate the applicability to the HTS cable. Moreover, we have developed some technologies to bring out latent potentials of YBCO tapes.

  8. Dynamic corona characteristics of water droplets on charged conductor surface

    Science.gov (United States)

    Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

    2017-03-01

    The formation of the Taylor cone of a water droplet on the surface of the conductor in a line-ground electrode system is captured using a high-speed camera, while the corona current is synchronously measured using a current measurement system. Repeated Taylor cone deformation is observed, yielding regular groupings of corona current pulses. The underlying mechanism of this deformation is studied and the correlation between corona discharge characteristics and cone deformation is investigated. Depending on the applied voltage and rate of water supply, the Taylor cone may be stable or unstable and has a significant influence on the characteristics of the corona currents. If the rate of water supply is large enough, the Taylor cone tends to be unstable and generates corona-current pulses of numerous induced current pulses with low amplitudes. In consequence, this difference suggests that large rainfall results in simultaneously lower radio interference and higher corona loss.

  9. Actitudes hacia comportamientos protectores y de riesgo en conductores costarricenses

    Directory of Open Access Journals (Sweden)

    Marjorie Moreno Salas

    2011-12-01

    Full Text Available En el presente estudio se exploraron las actitudes y los comportamientos protectores y de riesgo al conducir vehículos particulares en una muestra de 590 conductores de entre 20 y 60 años (M = 38,57, DE =11,69 residentes del área metropolitana costarricense. Se realizó una investigación exploratoria, desarrollada mediante un diseño transversal con un cuestionario autoaplicado. Los principales resultados fueron que: A mayor cantidad de hijos e hijas dependientes, menores comportamientos y actitudes hacia el riesgo y mayores comportamientos protectores. A mayor cantidad de años de tener licencia, menores actitudes hacia el exceso de velocidad y menores comportamientos de riesgo asociados con la alta velocidad. Entre más días de manejo, mayores comportamientos protectores. A mayor reporte de actitudes y comportamientos favorables hacia el riesgo, menor edad de los participantes. A manera de conclusión, las actitudes y los comportamientos de riesgo se vinculan negativamente. Además, variables sociodemográficas como el número de hijos y la edad de los conductores modula la respuesta en cuanto a las actitudes y los comportamientos protectores y de riesgo al manejar. Los resultados del estudio forman un primer aporte a la investigación nacional en el tema, en tanto, se cuenta con un instrumento susceptible de ser aplicado en otros estudios y múltiples datos empíricos en la temática.

  10. Manufacture of the poloidal field conductor insert coil (PFCI)

    Energy Technology Data Exchange (ETDEWEB)

    Baker, W. [EFDA CSU Garching, Boltzmannstrasse 2, 85748 Garching bei Muenchen (Germany); Keefe, C. [Tesla Engineering, Storrington, Sussex (United Kingdom); Rajainmaeki, H. [EFDA CSU Garching, Boltzmannstrasse 2, 85748 Garching bei Muenchen (Germany)], E-mail: hannu.rajainmaki@tech.efda.org; Salpietro, E. [EFDA CSU Garching, Boltzmannstrasse 2, 85748 Garching bei Muenchen (Germany)

    2007-10-15

    Within the framework of the R and D programme for international thermonuclear experimental reactor (ITER) the European team European Fusion Development Agreement (EFDA) has been charged with the design and manufacture of the poloidal field conductor insert coil (PFCI). The purpose of the PFCI is to test and demonstrate the performance of long-length full-scale NbTi conductors in ITER-relevant conditions. The PFCI will be tested in the central solenoid model coil test facility at the JAEA, Naka, Japan. This paper details the complete manufacturing of the PFCI including development, forming machining, pre-assembly, impregnation, final assembly and testing. The PFCI is a single-layered wound solenoid of nine turns with a transition joggle in the centre section of the winding and an intermediate joint connection between the upper termination and the main coil winding. To give the required overall dimensions to fit in the testing facility, preformed and machined glass resin composite filler pieces are assembled with the winding and is finally vacuum pressure impregnated (VPI) to create a single assembly unit. The PFCI is enclosed for assembly in a support structure, which consists of an upper and lower flange, each made up of four electrically insulated machined stainless steel castings, and 12 tie rods preloading the complete assembly in the vertical direction. The upper flange is equipped with four radial restraining jacks and the lower flange is equipped with four sets of studs and shear keys to withstand the net vertical and lateral electromagnetic forces. The PFCI is equipped with inductive heaters, voltage taps, temperature transducers, strain gauges and other instrumentation as diagnostics to monitor the performance. The current status of the manufacture is that the coil has passed the final acceptance tests and it is in the support structure assembly stage.

  11. Performance analysis of the Nb-Ti conductor qualification samples for the ITER project

    Science.gov (United States)

    Breschi, M.; Carati, D.; Bessette, D.; Devred, A.; Romano, G.; Vostner, A.; Zhou, C.

    2015-11-01

    The ITER machine will require approximately 275 tons of Nb-Ti strands that will be used in poloidal field (PF) coils, correction coils (CC) and feeder busbars. The performance of all these conductors for the ITER machine is qualified by a short full-size sample (4 m) current sharing temperature (T cs) test in the SULTAN facility at CRPP in Villigen, Switzerland, at the design operating current and peak field. Three ITER domestic agencies participated in PF conductor fabrication (China, the European Union, Russia) while the conductors for feeder busbars and correction coils are entirely produced by the Chinese domestic agency. Each conductor type was qualified by the ITER International Organization after reaching T cs values in excess of ITER specifications. This qualification enabled the launch of procurement and industrial production of the Nb-Ti cable-in-conduit conductors in each domestic agency. In this paper, we summarize the performance of the qualified Nb-Ti samples of the ITER Project, comparing strand performance with conductor performance. The details of the test results will be discussed in terms of dc performance, ac losses and minimum quench energies of each conductor type.

  12. A Novel Method for Detection and Classification of Covered Conductor Faults

    Directory of Open Access Journals (Sweden)

    Stanislav Misak

    2016-01-01

    Full Text Available Medium-Voltage (MV overhead lines with Covered Conductors (CCs are increasingly being used around the world primarily in forested or dissected terrain areas or in urban areas where it is not possible to utilize MV cable lines. The CC is specific in high operational reliability provided by the conductor core insulation compared to Aluminium-Conductor Steel-Reinforced (ACSR overhead lines. The only disadvantage of the CC is rather the problematic detection of faults compared to the ACSR. In this work, we consider the following faults: the contact of a tree branch with a CC and the fall of a conductor on the ground. The standard protection relays are unable to detect the faults and so the faults pose a risk for individuals in the vicinity of the conductor as well as it compromises the overall safety and reliability of the MV distribution system. In this article, we continue with our previous work aimed at the method enabling detection of the faults and we introduce a method enabling a classification of the fault type. Such a classification is especially important for an operator of an MV distribution system to plan the optimal maintenance or repair the faulty conductors since the fall of a tree branch can be solved later whereas the breakdown of a conductor means an immediate action of the operator.

  13. Electrohydrodynamic direct—writing of conductor—insulator-conductor multi-layer interconnection

    Science.gov (United States)

    Zheng, Gao-Feng; Pei, Yan-Bo; Wang, Xiang; Zheng, Jian-Yi; Sun, Dao-Heng

    2014-06-01

    A multi-layer interconnection structure is a basic component of electronic devices, and printing of the multi-layer interconnection structure is the key process in printed electronics. In this work, electrohydrodynamic direct-writing (EDW) is utilized to print the conductor—insulator—conductor multi-layer interconnection structure. Silver ink is chosen to print the conductor pattern, and a polyvinylpyrrolidone (PVP) solution is utilized to fabricate the insulator layer between the bottom and top conductor patterns. The influences of EDW process parameters on the line width of the printed conductor and insulator patterns are studied systematically. The obtained results show that the line width of the printed structure increases with the increase of the flow rate, but decreases with the increase of applied voltage and PVP content in the solution. The average resistivity values of the bottom and top silver conductor tracks are determined to be 1.34 × 10-7 Ω·m and 1.39 × 10-7 Ω·m, respectively. The printed PVP layer between the two conductor tracks is well insulated, which can meet the insulation requirement of the electronic devices. This study offers an alternative, fast, and cost-effective method of fabricating conductor—insulator—conductor multi-layer interconnections in the electronic industry.

  14. The dependence of AC loss characteristics on the space in stacked YBCO conductors

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Zhenan [Department of Electrical and Computer Engineering, Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Amemiya, Naoyuki [Department of Electrical and Computer Engineering, Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya, Yokohama 240-8501 (Japan); Kakimoto, Kazuomi [Materials Research Laboratory, Fujikura Ltd, 1-5-1 Kiba, Koto, Tokyo 135-8512 (Japan); Iijima, Yasuhiro [Materials Research Laboratory, Fujikura Ltd, 1-5-1 Kiba, Koto, Tokyo 135-8512 (Japan); Saitoh, Takashi [Materials Research Laboratory, Fujikura Ltd, 1-5-1 Kiba, Koto, Tokyo 135-8512 (Japan); Shiohara, Yuh [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto, Tokyo 135-0062 (Japan)

    2008-01-15

    Four 5 mm wide YBCO conductors were assembled face to face to obtain a stacked YBCO conductor (YBCO stack). The space between the conductors composing the YBCO stack was set at 1.0 mm to investigate the influence of the space on AC loss characteristics. The magnetization losses without transport current, the transport losses without external magnetic field, and total AC losses of the YBCO stack carrying various transport currents in transverse magnetic fields with various orientations were measured. The measured AC losses in the YBCO stack were compared with those in a 0.2 mm space YBCO stack composed of the same conductors used in the 1.0 mm space YBCO stack as well as a single YBCO conductor. Magnetization loss without transport current in a YBCO stack decreases with decreasing space between the conductors in low and intermediate magnetic field. Transport loss without external magnetic field in a YBCO stack increases with decreasing space between conductors. There are three characterized regions, when comparing the total AC losses in the two YBCO stacks with different space between the conductors composing the stacks: (a) in the low magnetic field region, the total AC losses in the YBCO stack with smaller space are larger than those in the YBCO stack with larger space, (b) in the intermediate magnetic field region, the total AC losses in the YBCO stack with smaller space are larger than those in the YBCO stack with larger space, (c) in the high magnetic field region, the total AC losses in both YBCO stacks agree well with those in the single YBCO conductor as well as Brandt and Indembom's analytical values.

  15. Assessment of the noise annoyance among subway train conductors in Tehran, Iran.

    Science.gov (United States)

    Hamidi, Mansoureh; Kavousi, Amir; Zaheri, Somayeh; Hamadani, Abolfazl; Mirkazemi, Roksana

    2014-01-01

    Subway transportation system is a new phenomenon in Iran. Noise annoyance interferes with the individual's task performance, and the required alertness in the driving of subway trains. This is the first study conducted to measure the level of noise and noise annoyance among conductors of subway organization in Tehran, Iran. This cross sectional study was conducted among 167 randomly selected train conductors. Information related to noise annoyance was collected by using a self-administered questionnaire. The dosimetry and sound metering was done for the conductors and inside the cabins. There were 41 sound metering measuring samples inside the conductors' cabin, and there were 12 samples of conductors' noise exposure. The results of sound level meter showed that the mean Leq was 73.0 dBA ± 8.7 dBA and the dosimetry mean measured Leq was 82.1 dBA ± 6.8 dBA. 80% of conductors were very annoyed/annoyed by noise in their work place. 53.9% of conductors reported that noise affected their work performance and 63.5% reported that noise causes that they lose their concentration. The noise related to movement of train wheels on rail was reported as the worst by 83.2% followed by the noise of brakes (74.3%) and the ventilation noise (71.9%). 56.9% of conductors reported that they are suffering from sleeplessness, 40.1% from tinnitus and 80.2% feeling fatigue and sleepy. The study results showed the high level of noise and noise annoyance among train conductors and the poor health outcome of their exposure to this level of noise.

  16. Investigation of the pre-service science teachers' opinions about the concept of "Semi-conductor"

    Science.gov (United States)

    Eryilmaz Muştu, Özlem

    2017-02-01

    In the current study, the purpose was to determine the pre-service science teachers' opinions about the concept of semi-conductor. The participants of the current study carried out in 2015-2016 academic year were 55 third year pre-service science teachers. In the study, open-ended questions were used to determine the pre-service teachers' opinions about semi-conductors. After the administration of the open-ended questions, the students were taught the topic of semi-conductors within the lesson of special issues in physics. Then the open-ended questions were directed to the pre-service teachers again. The pre-service teachers' responses to these questions were categorized by using qualitative analysis method and their frequency values were obtained. The findings of the study revealed that the pre-service teachers had difficulties, before and after the administration of the questions, in defining semi-conductors. At the end of the study, the pre-service teachers were found to have some misconceptions; for example, they think that semi-conductors conduct the half of the electricity conducted by conductors. In the study, it was found that the pre-service teachers cannot define the concept of semi-conductor and this might indicate that they will not be able to teach this concept when they become teachers. In this connection, it can be suggested that studies and activities performed for teaching of abstract concepts such as conductor, semi-conductor, and insulator should be increased.

  17. Theoretical simulations of proton conductivity: Basic principles for improving the proton conductor

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, D.W.M.; Kuleshova, L.N.; D' Aguanno, B. [CRS4, Parco Scientifico e Technologico, Sardegna Ricerca, Edificio 1, Loc. Piscina Mana, Pula 09010 (Italy)

    2010-12-01

    Classical molecular dynamics (MD) simulations of proton conduction have been performed, to get insight into basic principles of potential improvements of proton conductivity in polyelectrolyte membranes. For the simulations the reactive force field for water (RWFF) was used, which allows bond dissociation of water, acids and hydronium ions. The effects are shown to be fundamental relevance for the diffusion of protons in membranes. One and two-dimensional conductors, and a Nafion trademark membrane have been modeled in our simulations. The two-dimensional model imitates a metal phosphate; the one-dimensional model imitates an idealized pore of hydrated Nafion membranes. The MD simulations of proton conductivity of the metal phosphate show the dissociation of the acid -POH groups and their participation in the proton transport. Several simulations are performed with acids of different strength and the effect of the acid's strength on the diffusion and on the conductivity is analyzed. The importance of the ion coupling on the conductivity is firstly proved in tubes, which imitate an ideal pore inside a membrane. Afterwards, the coupling is investigated in a real hydrated Nafion membrane by a non-equilibrium MD simulation. The results suggest a soliton-like behavior for proton conductivity in membranes. (author)

  18. Shubnikov-de Haas Oscillations in New Organic Conductors (ET)8[ Hg4Cl12(C6H5Cl)2] and (ET)8[ Hg4Cl12(C6H5Br)2

    OpenAIRE

    Lyubovskii, R.; Pesotskii, S.; Gilevski, A.; Lyubovskaya, R.

    1996-01-01

    The results of the investigations of Shubnikov-de Haas oscillations in the quasi-two-dimensional organic complexes (ET)8[ Hg4Cl12(C6H5Cl)2] , where X = CI, Br in the magnetic fields up to 40 T were reported. These results allow one to obtain some information about Fermi surface in the mentioned complexes. Shubnikov-de Haas oscillations in the compound with X = Cl correspond at least to two different cylindrical sheets of Fermi surface with the cross-section in (bc)-plane of 13% and 20% Brillo...

  19. Development of multifilamentary Nb/sub 3/Sn conductors for fusion research

    Energy Technology Data Exchange (ETDEWEB)

    Cornish, D.N.; Deis, D.W.; Nelson, R.L.; Scanlan, R.M.; Taylor, C.E.; Vandervoort, R.R.; Wittmayer, F.J.; Zbasnik, J.P.

    1976-08-17

    A program at Lawrence Livermore Laboratory to develop multifilamentary Nb/sub 3/Sn conductors suitable for use in constructing fusion research magnets has resulted in the commercial production of conductors having cross-sectional areas in the range 0.06 cm/sup 2/ to 0.84 cm/sup 2/. Critical current densities near the goal of 10/sup 4/ A/cm/sup 2/ at 12 T and 4.2 K have been obtained in conductors produced by two different techniques. The latest results of this program are presented and discussed.

  20. AFM multilayered Bi-2223 conductors for 13,000 A current leads for CERN

    CERN Document Server

    Martini, L; Berti, R; Volpini, G; Bigoni, L; Curcio, F

    2000-01-01

    Large current carrying capacity multilayered Bi-2223 conductors are reproducibly prepared by means of the "Accordion-Folding Method" and suitably used to manufacture the low temperature stage of 13,000 A hybrid metal-HTS current lead prototypes for CERN. In this work, we report on the electrical characterisation of AFM multilayered Bi-2223 conductors having critical current as high as 400 A at 77 K and on a specific experimental set-up that has been developed to study the thermo-electrical performances of the AFM Bi-2223 composite conductors during the sudden resistive transition of the HTS: quench event. (4 refs).

  1. Current and field distributions of a superconducting power transmission cable composed of helical tape conductors

    Science.gov (United States)

    Tominaka, Toshiharu

    2009-12-01

    The current distributions within a power transmission cable composed of helically wound long tape superconductors have been studied by solving the circuit equation with the inductance matrix among divided segments within a tape conductor under the Bean model. The self- and mutual inductances of helical thin tape conductors are calculated from the analytical expressions in the form of an infinite series. In addition, it is shown that the distinction between the right-handed and left-handed helixes is generally necessary in the mutual inductance between two long coaxial helical conductors.

  2. Current and field distributions of a superconducting power transmission cable composed of helical tape conductors

    Energy Technology Data Exchange (ETDEWEB)

    Tominaka, Toshiharu, E-mail: tominaka@mext.go.j, E-mail: tominaka@riken.j [Ministry of Education, Culture, Sports, Science and Technology (MEXT), 3-2-2 Kasumigaseki, Chiyoda-ku, Tokyo 100-8959 (Japan); RIKEN - Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2009-12-15

    The current distributions within a power transmission cable composed of helically wound long tape superconductors have been studied by solving the circuit equation with the inductance matrix among divided segments within a tape conductor under the Bean model. The self- and mutual inductances of helical thin tape conductors are calculated from the analytical expressions in the form of an infinite series. In addition, it is shown that the distinction between the right-handed and left-handed helixes is generally necessary in the mutual inductance between two long coaxial helical conductors.

  3. Fabrication and modeling of stretchable conductors for traumatic brain injury research

    Science.gov (United States)

    Cao, Wenzhe

    Stretchable electronics are an emergent class of electronics that can retain their electric functionality under large mechanical deformation, such as stretching, bending and compression. Like traditional electric circuits, stretchable electronics rely on electrical conductors, but in this specific instance the conductors must also be stretchable. This thesis research had three goals: (1) fabricate elastically stretchable conductors that retain their electrical conductance when stretched by tens of percent of strain; (2) understand the underlying stretching mechanism of gold conductors on polydimethylsiloxane (PDMS) substrates; (3) produce a special device---a stretchable microelectrode array, which contains a matrix of stretchable conductors that enables a new approach to studying traumatic brain injury. We first developed and optimized the micro-fabrication process to make elastically stretchable thin gold film conductors on PDMS substrates. The conductors can retain electrical conduction while being stretched reversibly to 140% uniaxially and 16% radially. We further developed a fabrication process to encapsulate the conductors with either a commercially available photopatternable silicone (PPS) or with PDMS. 100 microm by 100 microm vias were patterned in the encapsulation layer to expose electrical contacts. PPS encapsulated conductors can be stretched uniaxially to 80%, and the PDMS encapsulated conductor can be stretched to ˜15%, without losing electrical conduction. We also introduced acrylate-based shape memory polymers (SMPs) as a new type of substrate for stretchable conductors. Their stiffness can be tuned by varying the monomer composition or by changing the ambient temperature. Thin gold film conductors deposited on pre-strained SMPs remain conductive when first stretched and then relaxed to their pre-strain value. Moreover, an SMP can also serve as a stretchable carrier to make pre-strained conductors on an overlying PDMS membrane. The resistance of

  4. Evaluation of molecular dynamics simulation methods for ionic liquid electric double layers

    Science.gov (United States)

    Haskins, Justin B.; Lawson, John W.

    2016-05-01

    We investigate how systematically increasing the accuracy of various molecular dynamics modeling techniques influences the structure and capacitance of ionic liquid electric double layers (EDLs). The techniques probed concern long-range electrostatic interactions, electrode charging (constant charge versus constant potential conditions), and electrolyte polarizability. Our simulations are performed on a quasi-two-dimensional, or slab-like, model capacitor, which is composed of a polarizable ionic liquid electrolyte, [EMIM][BF4], interfaced between two graphite electrodes. To ensure an accurate representation of EDL differential capacitance, we derive new fluctuation formulas that resolve the differential capacitance as a function of electrode charge or electrode potential. The magnitude of differential capacitance shows sensitivity to different long-range electrostatic summation techniques, while the shape of differential capacitance is affected by charging technique and the polarizability of the electrolyte. For long-range summation techniques, errors in magnitude can be mitigated by employing two-dimensional or corrected three dimensional electrostatic summations, which led to electric fields that conform to those of a classical electrostatic parallel plate capacitor. With respect to charging, the changes in shape are a result of ions in the Stern layer (i.e., ions at the electrode surface) having a higher electrostatic affinity to constant potential electrodes than to constant charge electrodes. For electrolyte polarizability, shape changes originate from induced dipoles that soften the interaction of Stern layer ions with the electrode. The softening is traced to ion correlations vertical to the electrode surface that induce dipoles that oppose double layer formation. In general, our analysis indicates an accuracy dependent differential capacitance profile that transitions from the characteristic camel shape with coarser representations to a more diffuse

  5. On the Difference Between the Vacuum Casimir Energies for Grounded and Isolated Conductors

    CERN Document Server

    Fosco, C D; Mazzitelli, F D

    2016-01-01

    We study the vacuum (i.e., zero-temperature) Casimir energy for a system of neutral conductors which are isolated, as opposed to grounded. The former is meant to describe a situation where the total charge on each conductor, as well as all of its fluctuations, vanishes, while the latter describes a situation where the conductors are connected to a charge reservoir. We compute the difference between the vacuum energies for a given system of conductors, but subjected to the two different conditions stated above. The results can be written in terms of a generalized, frequency-dependent capacitance matrix of the system. Using a multipolar expansion, we show that the grounded Casimir energy includes a monopole-monopole interaction term that is absent in the isolated case in the large distance limit

  6. New theorem of classical electromagnetism: equilibrium magnetic field and current density are zero inside ideal conductors

    CERN Document Server

    Fiolhais, Miguel C N; Providencia, C; Nordmark, Arne B

    2010-01-01

    We prove a theorem on the magnetic energy minimum in a system of perfect, or ideal, conductors. It is analogous to Thomson's theorem on the equilibrium electric field and charge distribution in a system of conductors. We first prove Thomson's theorem using a variational principle. Our new theorem is then derived by similar methods. We find that magnetic energy is minimized when the current distribution is a surface current density with zero interior magnetic field; perfect conductors are perfectly diamagnetic. The results agree with currents in superconductors being confined near the surface. The theorem implies a generalized force that expels current and magnetic field from the interior of a conductor that loses its resistivity. Examples of solutions that obey the theorem are presented.

  7. Stress-tuned conductor-polymer composite for use in sensors

    Science.gov (United States)

    Martin, James E; Read, Douglas H

    2013-10-22

    A method for making a composite polymeric material with electrical conductivity determined by stress-tuning of the conductor-polymer composite, and sensors made with the stress-tuned conductor-polymer composite made by this method. Stress tuning is achieved by mixing a miscible liquid into the polymer precursor solution or by absorbing into the precursor solution a soluble compound from vapor in contact with the polymer precursor solution. The conductor may or may not be ordered by application of a magnetic field. The composite is formed by polymerization with the stress-tuning agent in the polymer matrix. The stress-tuning agent is removed following polymerization to produce a conductor-polymer composite with a stress field that depends on the amount of stress-tuning agent employed.

  8. MHD instabilities developing in a conductor exploding in the skin effect mode

    Science.gov (United States)

    Oreshkin, V. I.; Chaikovsky, S. A.; Datsko, I. M.; Labetskaya, N. A.; Mesyats, G. A.; Oreshkin, E. V.; Ratakhin, N. A.; Rybka, D. V.

    2016-12-01

    The results of experiments with exploding copper conductors, performed on the MIG facility (providing currents of amplitude of about 2.5 MA and rise time of 100 ns), are analyzed. With an frame optical camera, large-scale instabilities of wavelength 0.2-0.5 mm were detected on the conductor surface. The instabilities show up as plasma "tongues" expanding with a sound velocity in the opposite direction to the magnetic field gradient. Analysis performed using a two-dimensional MHD code has shown that the structures observed in the experiments were formed most probably due to flute instabilities. The growth of flute instabilities is predetermined by the development of thermal instabilities near the conductor surface. The thermal instabilities arise behind the front of the nonlinear magnetic diffusion wave propagating through the conductor. The wavefront on its own is not subject to thermal instabilities.

  9. Skin effect mitigation in laser processed multi-walled carbon nanotube/copper conductors

    Energy Technology Data Exchange (ETDEWEB)

    Keramatnejad, K.; Zhou, Y. S.; Gao, Y.; Rabiee Golgir, H.; Wang, M.; Lu, Y. F., E-mail: ylu2@unl.edu [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511 (United States); Jiang, L. [School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081 (China); Silvain, J.-F. [Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB-CNRS) 87, Avenue du Docteur Albert Schweitzer F-33608 Pessac Cedex (France)

    2015-10-21

    In this study, laser-processed multi-walled carbon nanotube (MWCNT)/Cu conductors are introduced as potential passive components to mitigate the skin effect of Cu at high frequencies (0–10 MHz). Suppressed skin effect is observed in the MWCNT/Cu conductors compared to primitive Cu. At an AC frequency of 10 MHz, a maximum AC resistance reduction of 94% was observed in a MWCNT/Cu conductor after being irradiated at a laser power density of 189 W/cm{sup 2}. The reduced skin effect in the MWCNT/Cu conductors is ascribed to the presence of MWCNT channels which are insensitive to AC frequencies. The laser irradiation process is observed to play a crucial role in reducing contact resistance at the MWCNT-Cu interfaces, removing impurities in MWCNTs, and densifying MWCNT films.

  10. Health effects of electromagnetic field generated by lightning current pulses near down conductors

    Science.gov (United States)

    Tamus, Z. Á.; Novák, B.; Szücs, L.; Kiss, I.

    2011-06-01

    The lightning current generates a time varying magnetic field near down conductors, when lightning strikes the connected Franklin-rod. The down conductors are mounted on the wall of buildings, where residential places can be situated. It is well known that the rapidly changing magnetic fields could generate dangerous eddy currents in the human body. If the duration and the gradient of the magnetic field were high enough, the peripheral nerves are excited. In this study, the authors introduce an improved model of the interaction of electromagnetic fields of lighting current near a down conductor with the human body. The interaction model has two parts: estimation of the magnetic fields surrounding the down conductor and evaluation of health effects of rapid changing magnetic fields on the human body.

  11. Stability of cable-in-conduit, force-cooled conductors: elementary theory

    Energy Technology Data Exchange (ETDEWEB)

    Dresner, L.

    1979-01-01

    The recovery of cable-in-conduit conductors cooled by supercritical helium has been studied. The initial perturbation is a sudden, uniform deposition of heat. The problem has been solved, and answers have been obtained in the form of simple closed formulas under the simplifying assumption of constant thermophysical properties. Stability-optimized conductors have been identified and simple formulas for their material composition are given. A rule of design of cable-in-conduit conductors based on the existence of stability-optimized conductors is suggested. Some ''zero-flow'' experiments of Miller et al. have been analyzed, and it has been determined that for these experiments the effective heat transfer coefficient during the period of recovery is approximately 1000 Wm/sup -2/K/sup -1/.

  12. On the electrostatic equilibrium of charges and cavities in a conductor

    CERN Document Server

    Pathak, Aritro

    2016-01-01

    We consider a charged conductor of arbitrary shape, in electrostatic equilibrium, with one or more cavities inside it, and with fixed charges placed outside the conductors and inside the cavities. The field inside a particular cavity is then only due to charges within that cavity itself and to the surface charge induced on the surface of the same cavity. A similar statement holds for the exterior of the conductor. Although this is an elementary property of conductors, it is not a trivial statement, as explained in this article. Undergraduate texts in electrodynamics do not discuss at length or provide a complete argument for an important problem such as this. Two simple and complete proofs are provided in this note with the help of the standard electrostatic uniqueness theorems.

  13. Metallographic autopsies of full-scale ITER prototype cable-in-conduit conductors after full cyclic testing in SULTAN: III. The importance of strand surface roughness in long twist pitch conductors

    Science.gov (United States)

    Sanabria, Charlie; Lee, Peter J.; Starch, William; Devred, Arnaud; Larbalestier, David C.

    2016-07-01

    As part of the ITER conductor qualification process, 3 m long cable-in-conduit conductors (CICCs) were tested at the SULTAN facility under conditions simulating ITER operation so as to establish the current-sharing temperature, T cs, as a function of multiple full Lorentz force loading cycles. After a comprehensive evaluation of both the toroidal field (TF) and the central solenoid (CS) conductors, it was found that T cs degradation was common in long twist pitch TF conductors while short twist pitch CS conductors showed some T cs increase. However, one kind of TF conductors containing superconducting strand fabricated by the Bochvar Institute of Inorganic Materials (VNIINM) avoided T cs degradation despite having long twist pitch. In our earlier metallographic autopsies of long and short twist pitch CS conductors, we observed a substantially greater transverse strand movement under Lorentz force loading for long twist pitch conductors, while short twist pitch conductors had negligible transverse movement. With help from the literature, we concluded that the transverse movement was not the source of T cs degradation but rather an increase of the compressive strain in the Nb3Sn filaments possibly induced by longitudinal movement of the wires. Like all TF conductors this TF VNIINM conductor showed large transverse motions under Lorentz force loading, but T cs actually increased, as in all short twist pitch CS conductors. We here propose that the high surface roughness of the VNIINM strand may be responsible for the suppression of the compressive strain enhancement (characteristic of long twist pitch conductors). It appears that increasing strand surface roughness could improve the performance of long twist pitch CICCs.

  14. Design of the HTS Fusion Conductors for TF and CS Coils

    OpenAIRE

    Bykovsky, Nikolay; Uglietti, Davide; Wesche, Rainer; Bruzzone, Pierluigi

    2016-01-01

    The main electrical and mechanical requirements for the LTS fusion conductors of DEMO are retained as a starting point for the development of HTS fusion cables. Based on the HTS coated conductor technology, a flat cable design was proposed by CRPP Swiss Plasma Center (SPC) using the strands made of twisted stack of tapes soldered into copper profiles. Analytical modeling of the cable geometry is developed and presented in this work. The model was used to estimate various properties of cable. ...

  15. Time-Domain Analysis of a Wire Antenna Near Arbitrarily Shaped Conductor Bodies

    Institute of Scientific and Technical Information of China (English)

    Zheng; Li-Zhi; Xiao; Bo-xun; 等

    2003-01-01

    A time domain electrical field integral equation (TDEFIE) is formulated for the problem of a thin wire antenna in the presence of conductor bodies, and this equation is solved by the method in time marching algorithm. The analysis is valid for any arbitrarily shaped, oriented and positioned wire antennas relative to arbitrarily shaped conductor bodies. Current at the excited point, input admittance and radiation pattern are given and agree with the results computed by the method in frequency domain.

  16. Time-Domain Analysis of a Wire Antenna Near Arbitrarily Shaped Conductor Bodies

    Institute of Scientific and Technical Information of China (English)

    Zheng Li-zhi; Xiao Bo-xur; Zhu Guo-qiang; Yang Zi-jie

    2003-01-01

    A time domain electrical field integral equation (TDEFIE) is formulated for the problem of a thin wire antenna in the presence of conductor bodies, and this equation is solved by the method of time marching algorithm. The analysis is valid for any arbitrarily shaped, oriented and positioned wire antennas relative to arbitrarily shaped conductor bodies. Current at the excited point, input admittance and radiation pattern are given and agree with the results computed by the method in frequency domain.

  17. Quench propagation in AFM Bi-2223 conductors for current lead applications

    CERN Document Server

    Martini, L; Berti, R; Bigoni, L; Putti, M; Volpini, G; Curcio, F

    2001-01-01

    In this paper, the authors report on the electrical and thermal properties of Bi-2223 composite conductors prepared by the "accordion-folding method" (AFM). Thermal behavior study on AFM Bi-2223 conductors similar to those that have been successfully used to assemble the cold stage of low-loss current leads for CERN, has been performed by using a newly developed experimental apparatus that is described in detail. (7 refs).

  18. Thermal hydraulic characteristics study of prototype NET and CEA cable-in-conduit conductors (CICCs)

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Ryuji

    1995-10-31

    The thermal hydraulic characteristics of low temperature helium in a Cable-in-Conduit Conductor (CICC) significantly affects the overall design and performance of the associated large scale superconducting magnet system. It is essential to understand the transient and steady state behavior of the helium in the conductor. Throughout the development of CICCs, the reduction of flow impedance has been one of the key factors to improving the overall pressure drop. The newly developed CICC for the ITER project has a hybrid cooling scheme: a central channel that is surrounded by bundles, for which the thermal hydraulic characteristics are not well understood. This thesis describes an experimental and analytical investigation of thermal hydraulic characteristics of low temperature helium in conventional and hybrid CICCS. Pressure drop measurements for both NET and CEA conductors have been conducted, using low temperature helium and liquid nitrogen to obtain a range of Reynolds numbers. The results are correlated with classical friction factor and Reynolds number analysis. The flow impedance reduction of the CEA conductor is described by measures of a developed flow model. Thermally induced flow in the CEA conductor has been studied with an inductive heating method. The induced velocity in the central channel is measured by a Pitot tube with steady state Reynolds number up to {approximately}7000. The transient pressure wave propagation has been recorded with pressure transducers placed equally along the conductor. The supercritical helium temperature in the central channel has been measured with the thermometer probe. However, the reduction of the central channel area significantly affects the overall thermal hydraulic characteristics of the conductor. The results suggest the importance of the central channel. A transient heat transfer experiment studied the.transverse heat transfer mechanism in the CEA conductor. The temperatures in the central channel and bundle region

  19. Thermal hydraulic characteristics study of prototype NET and CEA cable-in-conduit conductors (CICCs)

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Ryuji

    1995-10-31

    The thermal hydraulic characteristics of low temperature helium in a Cable-in-Conduit Conductor (CICC) significantly affects the overall design and performance of the associated large scale superconducting magnet system. It is essential to understand the transient and steady state behavior of the helium in the conductor. Throughout the development of CICCs, the reduction of flow impedance has been one of the key factors to improving the overall pressure drop. The newly developed CICC for the ITER project has a hybrid cooling scheme: a central channel that is surrounded by bundles, for which the thermal hydraulic characteristics are not well understood. This thesis describes an experimental and analytical investigation of thermal hydraulic characteristics of low temperature helium in conventional and hybrid CICCS. Pressure drop measurements for both NET and CEA conductors have been conducted, using low temperature helium and liquid nitrogen to obtain a range of Reynolds numbers. The results are correlated with classical friction factor and Reynolds number analysis. The flow impedance reduction of the CEA conductor is described by measures of a developed flow model. Thermally induced flow in the CEA conductor has been studied with an inductive heating method. The induced velocity in the central channel is measured by a Pitot tube with steady state Reynolds number up to {approximately}7000. The transient pressure wave propagation has been recorded with pressure transducers placed equally along the conductor. The supercritical helium temperature in the central channel has been measured with the thermometer probe. However, the reduction of the central channel area significantly affects the overall thermal hydraulic characteristics of the conductor. The results suggest the importance of the central channel. A transient heat transfer experiment studied the.transverse heat transfer mechanism in the CEA conductor. The temperatures in the central channel and bundle region

  20. Interfaces in Dye-Sensitized Oxide / Hole-Conductor Heterojunctions for Solar Cell Applications

    OpenAIRE

    Johansson, Erik

    2006-01-01

    Nanoporous dye-sensitized solar cells (DSSC) are promising devices for solar to electric energy conversion. In this thesis photoelectron spectroscopy (PES), x-ray absorption spectroscopy (XAS) and photovoltaic measurements are used for studies of the key interfaces in the DSSC. Photovoltaic properties of new combinations of TiO2/dye/hole-conductor heterojunctions were demonstrated and their interfacial structures were studied. Three different types of hole-conductor materials were investigate...

  1. Doped Y.sub.2O.sub.3 buffer layers for laminated conductors

    Science.gov (United States)

    Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA

    2007-08-21

    A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the metallic substrate, the biaxially textured buffer layer comprising Y.sub.2O.sub.3 and a dopant for blocking cation diffusion through the Y.sub.2O.sub.3, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

  2. Analysis of Cable-in-Conduit Conductors' DC Performance in Light of Strand's Experimental Properties

    Institute of Scientific and Technical Information of China (English)

    TAN Yunfei; WENG Peide; LIU Fang; LI Shaolei

    2007-01-01

    Conductor qualification will be carried out with four Cable-in-Conduit Conductor (CICC) samples made of superconducting strands. The direct current (DC) performance of these samples will be tested in the SULTAN facility. The critical current densities of the strands can be well simulated by empirical equations. In this paper, a model is illustrated to predict the DC behaviour of the cable in light of the single strand's experimental properties. The simulation results were compared with experimental results.

  3. Bipolar energy-loss measurements on cryostable, low-loss conductors

    Science.gov (United States)

    Wollan, J. J.

    1981-11-01

    Losses have been measured on a prototype conductor for the 20 MJ coil for conditions which simulate closely the actual coil field sweep. The data on the prototype II conductor indicates coil losses which exceed the coil specification. The application of certain correction factors reduces the projected losses within the specification for a 2 s reversal but not for a 1 s reversal. Verification of these corrections await measurements on the actual strand and completion of coil construction and testing.

  4. Bipolar energy-loss measurements on cryostable, low-loss conductors

    Energy Technology Data Exchange (ETDEWEB)

    Wollan, J.J.

    1981-01-01

    Losses have been measured on a prototype conductor for the 20 MJ coil for conditions which simulate closely the actual coil field sweep. The data on the prototype II conductor indicates coil losses which exceed the coil specification. The application of certain correction factors reduces the projected losses within the specification for a 2 s reversal but not for a 1 s reversal. Verification of these corrections await measurements on the actual strand and completion of coil construction and testing.

  5. Feasibility of Using Aluminum Conductor Cables for Shore-to-Ship Electrical Power Service

    Science.gov (United States)

    1976-01-01

    power cable is about one-half the cost of the same ampacity copper conductor power cable . Disadvantages of Aluminum...Discussion Electrical power cables constructed in accordance ith MIL-C-915/6 are designed with a maximum operating temperature of 75 C. Therefore, the ampacity ... cable . Passaic, NJ. 5. Murray W. Davis. ’’Nomographic computation of the ampacity rating of aerial conductors,’’ IEEE Transactions on Power

  6. Electrical explosion of a conductor in energy accumulating phase change materials with nanosized semiconducting additions

    Science.gov (United States)

    Savenkov, G. G.; Morozov, V. A.; Lukin, A. A.

    2016-11-01

    The results of experiments on the explosion of a copper conductor in paraffin and wax both without additions and with nanosized copper oxide additions are presented. The experiments provided the size of the channel formed in wax samples upon the conductor explosion and subsequent expansion of the electric discharge plasma. The obtained results testify to the influence of nanosized additions on the character of electric discharge plasma expansion in the formed channel, the strength of composite materials, and the sample fragmentation (destruction).

  7. The Integration of YBCO Coated Conductors into Magnets and Rotating Machinery (Postprint)

    Science.gov (United States)

    2012-02-01

    AFRL-RZ-WP-TP-2012-0119 THE INTEGRATION OF YBCO COATED CONDUCTORS INTO MAGNETS AND ROTATING MACHINERY (POSTPRINT) G.A. Levin and P.N...COVERED (From - To) February 2012 Conference Paper Postprint 01 January 2004 – 01 January 2006 4. TITLE AND SUBTITLE THE INTEGRATION OF YBCO COATED...Keystone, CO (August 29-September 2, 2005) The Integration of YBCO Coated Conductors into Magnets and Rotating Machinery G. A. Levin and P. N. Barnes

  8. Stability and Normal Zone Propagation Speed in YBCO Coated Conductors with Increased Interfacial Resistance (PREPRINT)

    Science.gov (United States)

    2010-03-01

    AFRL-RZ-WP-TP-2010-2085 STABILITY AND NORMAL ZONE PROPAGATION SPEED IN YBCO COATED CONDUCTORS WITH INCREASED INTERFACIAL RESISTANCE...August 2006 – 25 August 2008 4. TITLE AND SUBTITLE STABILITY AND NORMAL ZONE PROPAGATION SPEED IN YBCO COATED CONDUCTORS WITH INCREASED INTERFACIAL...reproduce, release, perform, display, or disclose the work. 14. ABSTRACT We will discuss how stability and speed of normal zone propagation in YBCO

  9. Magnetic Field Design of Coil-Dominated Magnets Wound With Coated Conductors

    OpenAIRE

    Takahashi, Keita; Amemiya, Naoyuki; Nakamura, Taketsune; MORI, YOSHIHARU; Ogitsu, Toru; Yoshimoto, Masahiro; WATANABE, Ikuo; Yoshiyuki, Takeshi

    2012-01-01

    Coil-dominated magnets wound with coated conductors were designed for an FFAG accelerator for carbon therapy, which was designed by applying linear approximation. When designing the coil-end of the magnets, we applied differential geometry. To apply the differential geometry to three-dimensional windings with coated conductors, we introduced the concept of generalized flat-wise bending. Thereby, the combination of flat-wise bending and torsion was considered as bending of developable surface....

  10. Tuning magnetic properties in quasi-two-dimensional ferromagnetic Fe3‑y Ge1‑x As x Te2 (0  ⩽  x  ⩽  0.85)

    Science.gov (United States)

    Yuan, Duanduan; Jin, Shifeng; Liu, Ning; Shen, Shijie; Lin, Zhiping; Li, Kunkun; Chen, Xiaolong

    2017-03-01

    We report that Fe3GeTe2 can form a wide solid solution by substitution of As for Ge, providing an opportunity to tune the magnetic and electronic properties in this 2D material. The crystal structure, physical properties and electronic structure of iron-deficient solid solution Fe3‑y Ge1‑x As x Te2 (0  ⩽  x  ⩽  0.85) are studied. We found that the Curie temperature can substantially change from 177 K to 33 K and resistivity decreases by about 30% with the arsenic doping x from 0 to 0.85. First principles calculations demonstrate that the elongation of Fe(1)–Fe(1) dumb-bells along c axis is essentially responsible for decreasing the integrated spin density of states below Fermi level and weakening spin polarization, resulting in a decrease of Curie temperature. Our study reveals the magnetism manipulation can be realized via modification of bondlengths in 2D magnetic materials.

  11. The temperature dependences of the electron-deformation potential phonon interacting system of a quasi two dimensional system under circularly-oscillating fields in CdS, GaN and ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Sug, J. Y. [Kyungpook National University, Daegu (Korea, Republic of); Lee, S. H.; Choi, S. Y. [Donga University, Busan (Korea, Republic of)

    2014-11-15

    We study the optical quantum transition line shapes and the optical quantum transition linewidths in relation to the magnetic-field-dependent properties of an electron-deformation potential phonon interaction system. We consider two systems - one is subject to right circularly oscillating external fields and the other is subject to left circularly-oscillatory external fields. We investigated theoretically the temperature dependence of the quantum optical transition of qusi-2-dimensional Landau splitting ystem in CdS, GaN and ZnO.

  12. Manufacturing and test of 2G-HTS coils for rotating machines: Challenges, conductor requirements, realization

    Energy Technology Data Exchange (ETDEWEB)

    Oomen, Marijn, E-mail: marijn.oomen@siemens.com [Siemens AG, Corporate Technology, CT T DE HW4, PO Box 3220, 91050 Erlangen (Germany); Herkert, Werner; Bayer, Dietmar; Kummeth, Peter; Nick, Wolfgang; Arndt, Tabea [Siemens AG, Corporate Technology, CT T DE HW4, PO Box 3220, 91050 Erlangen (Germany)

    2012-11-20

    We investigate the use of 2nd-generation High-Temperature Superconductors (2G-HTSs) in the rotors of electrical motors and generators. For these devices the conductor must be wound into robust impregnated coils, which are operated in vacuum at temperatures around 30 K, in strong magnetic fields of about 2T. Differences in thermal contraction between the coil former, conductor constituents, impregnation resin, bandage and heat-sink materials (assembled at room temperature) cause mechanical stresses at operating temperature. Rotating-machine operation adds Lorentz forces and challenging centripetal accelerations up to thousands of g. Second generation-HTS conductors withstand large tensile stresses in axial direction and compression in normal direction. However, shear stresses, axial compression, and tension normal to the conductor can cause degradation in superconducting properties. Such stresses can be mitigated by correct choice of materials, coil lay-out and manufacturing process. A certain stress level will remain, which the conductor must withstand. We have manufactured many impregnated round and race-track coils, using different 2G-HTS conductors, and tested them at temperatures from 25 K to 77 K. Degradation of the superconductor in early coils was traced to the mentioned differences in thermal contraction, and was completely avoided in coils produced later. We will discuss appropriate coil-winding techniques to assure robust and reliable superconductor performance.

  13. Powder-in-tube (PIT) $Nb_{3}Sn$ conductors for high-field magnets

    CERN Document Server

    Lindenhovius, J L H; den Ouden, A; Wessel, W A J; ten Kate, H H J

    2000-01-01

    New Nb/sub 3/Sn conductors, based on the powder-in-tube (PIT) process, have been developed for application in accelerator magnets and high-field solenoids. For application in accelerator magnets, SMI has developed a binary 504 filament PIT conductor by optimizing the manufacturing process and adjustment of the conductor lay-out. It uniquely combines a non-copper current density of 2680 A/mm/sup 2/@10 T with an effective filament diameter of about 20 mu m. This binary conductor may be used in a 10 T, wide bore model separator dipole magnet for the LHC, which is being developed by a collaboration of the University of Twente and CERN. A ternary (Nb/7.5wt%Ta)/sub 3/Sn conductor containing 37 filaments is particularly suited for application in extremely high-field superconducting solenoids. This wire features a copper content of 43%, a non-copper current density of 217 A/mm/sup 2/@20 T and a B/sub c2/ of 25.6 T. The main issues and the experimental results of the development program of PIT Nb/sub 3/Sn conductors a...

  14. Test of 60 kA coated conductor cable prototypes for fusion magnets

    Science.gov (United States)

    Uglietti, D.; Bykovsky, N.; Sedlak, K.; Stepanov, B.; Wesche, R.; Bruzzone, P.

    2015-12-01

    Coated conductors could be promising materials for the fabrication of the large magnet systems of future fusion devices. Two prototype conductors (flat cables in steel conduits), each about 2 m long, were manufactured using coated conductor tapes (4 mm wide) from Super Power and SuperOx, with a total tape length of 1.6 km. Each flat cable is assembled from 20 strands, each strand consisting of a stack of 16 tapes surrounded by two half circular copper profiles, twisted and soldered. The tapes were measured at 12 T and 4.2 K and the results of the measurements were used for the assessment of the conductor electromagnetic properties at low temperature and high field. The two conductors were assembled together in a sample that was tested in the European Dipole (EDIPO) facility. The current sharing temperatures of the two conductors were measured at background fields from 8 T up to 12 T and for currents from 30 kA up to 70 kA: the measured values are within a few percent of the values expected from the measurements on tapes (short samples). After electromagnetic cycling, T cs at 12 T and 50 kA decreased from about 12 K to 11 K (about 10%), corresponding to less than 3% of I c.

  15. Manufacturing and test of 2G-HTS coils for rotating machines: Challenges, conductor requirements, realization

    Science.gov (United States)

    Oomen, Marijn; Herkert, Werner; Bayer, Dietmar; Kummeth, Peter; Nick, Wolfgang; Arndt, Tabea

    2012-11-01

    We investigate the use of 2nd-generation High-Temperature Superconductors (2G-HTSs) in the rotors of electrical motors and generators. For these devices the conductor must be wound into robust impregnated coils, which are operated in vacuum at temperatures around 30 K, in strong magnetic fields of about 2T. Differences in thermal contraction between the coil former, conductor constituents, impregnation resin, bandage and heat-sink materials (assembled at room temperature) cause mechanical stresses at operating temperature. Rotating-machine operation adds Lorentz forces and challenging centripetal accelerations up to thousands of g. Second generation-HTS conductors withstand large tensile stresses in axial direction and compression in normal direction. However, shear stresses, axial compression, and tension normal to the conductor can cause degradation in superconducting properties. Such stresses can be mitigated by correct choice of materials, coil lay-out and manufacturing process. A certain stress level will remain, which the conductor must withstand. We have manufactured many impregnated round and race-track coils, using different 2G-HTS conductors, and tested them at temperatures from 25 K to 77 K. Degradation of the superconductor in early coils was traced to the mentioned differences in thermal contraction, and was completely avoided in coils produced later. We will discuss appropriate coil-winding techniques to assure robust and reliable superconductor performance.

  16. DC ice-melting model for wet-growth icing conductor and its experimental investigation

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Icicles are often formed under the downside surface of conductor in the wet growth icing of overhead power line. When the ice deposit around overhead power line is molten by Joule heat produced by current, the pattern of heat transfer of ice deposit with icicles is dissimilar to that without icicle, so the ice-melting model for the columnar icing conductor cannot be applied to icicle-shaped icing conductor. According to the heat-transfer characteristic of the icicle-shaped icing conductor, this paper puts forward a DC ice-melting model for the icicle-shaped icing conductor. Because this full model includes three-dimensional heat-transfer and interface movement, which cannot be solved in closed form, a finite element scheme in space-domain and a finite difference scheme in time-domain are employed to discretize the governing equations. Firstly the whole ice-melting process on the icicle-shaped icing conductor is simulated by this model. Then the simulated results are validated by ice-melting experiments in the artificial chamber. The study from the model and the experiments shows that the size and length of icicle as well as the space between the adjacent icicles are factors to affect ice-melting. With the shorter icicle space, the bigger icicle size and the longer icicle-length, the surface of ice layer is enlarged and then more heat is taken away by the convection and radiation, so the ice melting time will get longer.

  17. Large Scale Assembly and Characterization of BI-2223 HTS Conductors

    CERN Document Server

    Ballarino, Amalia; Mathot, Serge; Taylor, T; Brambilla, R

    2007-01-01

    The powering of the LHC machine requires more than 1000 High Temperature Superconducting (HTS) current leads. These leads contain, at their cold end, HTS conductors made of stacks of Bi-2223 tape with gold-doped silver matrix. CERN specified and purchased 31 km of this material, which was delivered on spools in unit lengths of 100 to 300 m. On reception the tape was inspected, cut into short length and vacuum soldered into stacks. All stacks were characterized in liquid nitrogen using a measuring procedure and set-up specifically developed for this purpose. Contact resistance values and critical currents at different electric field criteria were measured, from which the n-values have been extrapolated from the experimental V-I characteristics. This paper reports on the assembly and electrical characterization (up to 800 A) of more than ten thousand Bi-2223 stacks. Three types of stack were made from tape from two manufacturers. The assembly and soldering procedures and the set-up for the series electrical cha...

  18. The superconducting strand for the CMS solenoid conductor

    CERN Document Server

    Curé, B; Campi, D; Goodrich, L F; Horváth, I L; Kircher, F; Liikamaa, R; Seppälä, J; Smith, R P; Teuho, J; Vieillard, L

    2002-01-01

    The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4 T, the magnetic length is 12.5 m and the free bore is 6 m. Approximately 2000 km of superconducting strand is under procurement for the conductor of the CMS superconducting solenoid. Each strand length is required to be an integral multiple of 2.75 km. The strand is composed of copper- stabilized multifilamentary Nb-Ti with Nb barrier. Individual strands are identified by distinctive patterns of Nb-Ti filaments selected during stacking of the monofilaments. The statistics of piece length, measurements of I/sub c/, n-value, copper RRR, (Cu+Nb)/Nb-Ti ratio, as well as the results of independent cross checks of these quantities, are presented. A study was performed on the CMS strands to investigate the critical current degradation due to various heat treatments. The degradation versus annealing temperature and duration are reported. (4 refs).

  19. Aluminum alloy production for the reinforcement of the CMS conductor

    CERN Document Server

    Sequeira-Lopes-Tavares, S; Campi, D; Curé, B; Horváth, I L; Riboni, P; Sgobba, Stefano; Smith, R P

    2002-01-01

    The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the Large Hadron Collider (LHC) project at CERN. The design field of the CMS superconducting magnet is 4 T, the magnetic length is 12.5 m and the free bore is 6 m. To reinforce the high-purity (99.998%) Al-stabilized conductor of the magnet against the magnetic loadings experienced during operation at 4.2 K, two continuous sections of Al-alloy (AA) reinforcement are Electron Beam (EB) welded to it. The reinforcements have a section of 24*18 mm and are produced in continuous 2.55 km lengths. The alloy EN AW-6082 has been selected for the reinforcement due to its excellent extrudability, high strength in the precipitation hardened states, high toughness and strength at cryogenic temperature and good EB weldability. Each of the continuous lengths of the reinforcement is extruded billet on billet and press quenched on-line from the extrusion temperature in an industrial extrusion plant. In order to insure the ready EB welda...

  20. Mixed conductor anodes: Ni as electrocatalyst for hydrogen conversion

    DEFF Research Database (Denmark)

    Primdahl, S.; Mogensen, Mogens Bjerg

    2002-01-01

    Five types of anodes for solid oxide fuel cells (SOFC) are examined on an yttria-stabilised zirconia (YSZ) electrolyte by impedance spectroscopy at 850 degreesC in hydrogen. The examined porous anodes are a Ni/Zr(0.92)Y(0.16)O(2.08) (Ni/YSZ) cermet, a Ni/Ce(0.9)Gd(0.1)O(1.95) (Ni/CGI) cermet, a Ce......(0.6)Gd(0.4)O(1.8) (CG4) ceramic, a La(0.75)Sr(0.25)Cr(0.97)V(0.03)O(3) (LSCV) ceramic and a Ti(0.22) Y(0.16)Zr(0.92)O(2.52) (TiYSZ) ceramic, Addition of small amounts ( approximate to I w/o) of Ni to the electrode surface is found to improve electrode performance on mixed electronic and ionic...... conductors (MIEC's), distinctly in the low-frequency part of the impedance spectra. An effect of isotope exchange (H(2)/H(2)O to D(2)/D(2)O) is observed for all anodes. The low-frequency limitation is suggested to be hydrogen adsorption and/or dissociation on the surface of MIEC electrodes, (C) 2002 Elsevier...

  1. Long Gd-123 coated conductor by PLD method

    Energy Technology Data Exchange (ETDEWEB)

    Fuji, H. [Fujikura Ltd., 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan)], E-mail: hfuji@fujikura.co.jp; Igarashi, M.; Hanada, Y.; Miura, T.; Hanyu, S.; Kakimoto, K.; Iijima, Y.; Saitoh, T. [Fujikura Ltd., 1-5-1, Kiba, Koto-ku, Tokyo 135-8512 (Japan)

    2008-09-15

    We have developed long Gd-123 coated conductors by ion-beam-assisted deposition (IBAD) and pulsed-laser-deposition (PLD) method. Recently, large-scale reel-to-reel apparatus with the 110 cm x 15 cm assisting ion source was introduced to IBAD system. It was enable to produce 500 m-class IBAD-Gd{sub 2}Zr{sub 2}O{sub 7} (GZO) tapes with {delta}{phi} of below 15 deg. and high throughputs of 3 m/h. Furthermore, apparatus with multi-lane and laser scanning was introduced to PLD system. As a result, end to end I{sub c} of 318 A were obtained for a 201.5 m long tape, and I{sub c} x L values were 64,077 Am. Furthermore, 500 m-class deposition was carried out by improving PLD conditions. As a result, I{sub c} x L values of 112,166 Am was obtained and it's a world record on August 2007. In the short samples, I{sub c} of over 500 A was obtained with Gd-123 thickness of 2.0 {mu}m and over 100 A was obtained in magnetic field of 3 T, perpendicular to c-axis.

  2. Guanidinium nonaflate as a solid-state proton conductor

    DEFF Research Database (Denmark)

    Chen, Xiaoli; Tang, Haolin; Putzeys, Tristan

    2016-01-01

    Protic organic ionic plastic crystals (POIPCs) are a type of novel solid-state proton conductors. In this work, guanidinium nonaflate ([Gdm-H][NfO]) is reported to be a model POIPC. Its structure-property relationship has been investigated comprehensively. Infrared analysis of [Gdm-H][NfO] and its...... deuterated analogue [Gdm-D][NfO] confirms the complete formation of the protic salts. The cations in as-prepared [Gdm-D][NfO] are estimated to consist of [C(ND2)2(NHD)]+ and [C(ND2)3]+ with a molar ratio of around 1:1. The deuteration also proves that each guanidinium cation has six displaceable protons...... order in the plastic crystalline phases. Dielectric spectroscopy measurements show that its ionic conductivity reaches 2.1 × 10-3 S cm-1 at 185 °C. The proton conduction in the plastic crystalline phases of [Gdm-H][NfO] is assumed to happen via the vehicle mechanism. In the molten state, the proton...

  3. A comparative analysis of graphene oxide films as proton conductors

    Science.gov (United States)

    Smirnov, V. A.; Denisov, N. N.; Dremova, N. N.; Vol'fkovich, Y. M.; Rychagov, A. Y.; Sosenkin, V. E.; Belay, K. G.; Gutsev, G. L.; Shulga, N. Yu.; Shulga, Y. M.

    2014-12-01

    The electrical conductivity of graphene oxide (GO) films in vapors of water and acid solutions is found to be close to the conductivity of a film formed after drying the solution of phenol-2,4-disulfonic acid in polyvinyl alcohol, which is known to be a proton conductor. We found that the conductivity of a GO film in vapors of the H2O-H2SO4 electrolyte possesses a sharp maximum at ~1 % by weight of sulfuric acid. The highest conductivity of GO films can be expected when placing the films over acid vapors where the acid concentration is essentially lower than in the acid solutions at their maximum conductivity. Since the conductivity of the H2O-H2SO4 electrolyte itself has a maximum at ~30 % by weight of sulfuric acid, the use of intermediate concentrations of H2SO4 is recommended in practical applications. The GO films permeated with water or acid solution in water are expected to possess the proton-exchange properties similar to those of other proton-exchanging membranes.

  4. Organic mixed conductors for bioelectronic applications (Conference Presentation)

    Science.gov (United States)

    Rivnay, Jonathan

    2016-09-01

    Direct measurement and stimulation of electrophysiological activity is a staple of neural and cardiac health monitoring, diagnosis and/or therapy. The ability to sensitively detect these signals can be enhanced by organic electronic materials that show mixed conduction properties (both electronic and ionic transport) in order to bridge the inherent mismatch that is prevalent between biological systems and traditional microelectronic materials/devices. Organic electrochemical transistors (OECTs) are one class of devices that utilize organic mixed conductors as the transistor channel, and have shown considerable promise as amplifying transducers due to their stability in aqueous conditions and high transconductance. These devices are fabricated in flexible, conformable form factors for in vivo recordings of epileptic activity, and for cutaneous EEG and ECG recordings in human subjects. The majority of high performance devices are based on conducting polymers such as poly(3,4-ethylenedioxythiophene) :poly(styrenesulfonate), PEDOT:PSS. By investigating PEDOT-based materials and devices, we are able to construct design rules for new formulations/materials. Introducing glycolated side chains to carefully selected semiconducting polymer backbones has enabled a new class high performance bioelectronic materials that feature high volumetric capacitance, transconductance >10mS (device dimensions ca. 10um), and steep subthreshold switching characteristics. A sub-set of these materials outperform PEDOT:PSS and shows significant promise for low power in vitro and in vivo biosensing applications.

  5. Comparative characterization of Cu–Ni substrates for coated conductors

    DEFF Research Database (Denmark)

    Tian, H.; Suo, H.L.; Wulff, Anders Christian;

    2014-01-01

    Three Cu100xNix alloys, with x = 23, 33 and 45 at.%Ni, have been evaluated for use as substrates for coated conductors on the basis of measurements of their microstructure, crystallographic texture and hardness. It is found that high-temperature annealing after heavy rolling generates strong cube...... textures in each investigated alloy. For all of these alloys an increase in the annealing temperature from 800 to 1000 C strengthens the cube texture and reduces the fraction of high angle grain boundaries. In the Cu–23 at.%Ni and Cu–33 at.%Ni alloys annealed at 1000 C for 1 h, the fraction of the cube...... texture approaches 100% and the fraction of high angle boundaries is less than 4%. These two alloys are however very soft in the annealed condition. The cube texture in the Cu–45 at.%Ni substrate is slightly weaker than in the two other alloys, but this substrate is considerably harder, which makes...

  6. Optimization study of normal conductor tokamak for commercial neutron source

    Science.gov (United States)

    Fujita, T.; Sakai, R.; Okamoto, A.

    2017-05-01

    The optimum conceptual design of tokamak with normal conductor coils was studied for minimizing the cost for producing a given neutron flux by using a system code, PEC. It is assumed that the fusion neutrons are used for burning transuranics from the fission reactor spent fuel in the blanket and a fraction of the generated electric power is circulated to opearate the tokamak with moderate plasma fusion gain. The plasma performance was assumed to be moderate ones; {β\\text{N}}~∼ ~3{--}4 in the aspect ratio A~=~2{--}3 and {{H}98y2}~=~1 . The circulating power is an important factor affecting the cost. Though decreasing the aspect ratio is useful to raise the plasma beta and decrease the toroidal field, the maximum field in the coil starts to rise in the very low aspect ratio range and then the circulating power increases with decrease in the plasma aspect ratio A below A~∼ ~2 , while the construction cost increases with A . As a result, the cost per neutron has its minimum around A~∼ ~2.2 , namely, between ST and the conventional tokamak. The average circulating power fraction is expected to be ~51%.

  7. Development of a Low-Cost ZIGBEE and GSM SMS-Based Conductor Temperature and Sag Monitoring System

    OpenAIRE

    M.V.Vijaya Saradhi; Nagaraju, S.

    2010-01-01

    This paper deals with the design, construction, instrumentation and testing of a GSM and ZIGBEE based monitoring system for the measurement of Overhead High Voltage (HV) Conductor Temperature and Sag. The main advantage of this concept is the real time direct measurement of the parameters (i.e., conductor sag and temperature) needed for the operation of the transmission system without intermediate measurement of conductor tension and ambient weather conditions, by which the temperature contro...

  8. Assessment of liquid hydrogen cooled MgB2 conductors for magnetically confined fusion

    Science.gov (United States)

    Glowacki, B. A.; Nuttall, W. J.

    2008-02-01

    Importantly environmental factors are not the only policy-driver for the hydrogen economy. Over the timescale of the development of fusion energy systems, energy security issues are likely to motivate a shift towards both hydrogen production and fusion as an energy source. These technologies combine local control of the system with the collaborative research interests of the major energy users in the global economy. A concept Fusion Island Reactor that might be used to generate H2 (rather than electricity) is presented. Exploitation of produced hydrogen as a coolant and as a fuel is proposed in conjunction with MgB2 conductors for the tokomak magnets windings, and electrotechnical devices for Fusion Island's infrastructure. The benefits of using MgB2 over the Nb-based conductors during construction, operation and decommissioning of the Fusion Island Reactor are presented. The comparison of Nb3Sn strands for ITER fusion magnet with newly developed high field composite MgB2 PIT conductors has shown that at 14 Tesla MgB2 possesses better properties than any of the Nb3Sn conductors produced. In this paper the potential of MgB2 conductors is examined for tokamaks of both the conventional ITER type and a Spherical Tokamak geometry. In each case MgB2 is considered as a conductor for a range of field coil applications and the potential for operation at both liquid helium and liquid hydrogen temperatures is considered. Further research plans concerning the application of MgB2 conductors for Fusion Island are also considered.

  9. Eddy damping effect of additional conductors in superconducting levitation systems

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Zhao-Fei; Gou, Xiao-Fan, E-mail: xfgou@hhu.edu.cn

    2015-12-15

    Highlights: • In this article, for the eddy current damper attached to the HTSC, we • quantitatively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. • presented four different arrangements of the copper damper, and comparatively studied their damping effects and Joule heating, and finally proposed the most advisable arrangement. - Abstract: Passive superconducting levitation systems consisting of a high temperature superconductor (HTSC) and a permanent magnet (PM) have demonstrated several fascinating applications such as the maglev system, flywheel energy storage. Generally, for the HTSC–PM levitation system, the HTSC with higher critical current density J{sub c} can obtain larger magnetic force to make the PM levitate over the HTSC (or suspended below the HTSC), however, the process of the vibration of the levitated PM, provides very limited inherent damping (essentially hysteresis). To improve the dynamic stability of the levitated PM, eddy damping of additional conductors can be considered as the most simple and effective approach. In this article, for the HTSC–PM levitation system with an additional copper damper attached to the HTSC, we numerically and comprehensively investigated the damping coefficient c, damping ratio, Joule heating of the copper damper, and the vibration frequency of the PM as well. Furthermore, we comparatively studied four different arrangements of the copper damper, on the comprehensive analyzed the damping effect, efficiency (defined by c/V{sub Cu}, in which V{sub Cu} is the volume of the damper) and Joule heating, and finally presented the most advisable arrangement.

  10. Phase behavior of a PVAL-based polymer proton conductor

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, M.A. [Univ. Popular del Cesar, Valledupar (Colombia). Dept. de Fisica; Vargas, R.A. [Dept. de Fisica, Univ. del Valle, Cali (Colombia); Mellander, B.-E. [Physics Dept., Chalmers Univ. of Technology, Gothenburg (Sweden)

    2000-07-01

    Solid protonic conductor gels were synthesized using poly(vinyl alcohol) (PVAL), hypophosphorous acid (H{sub 3}PO{sub 2}) and water as prime chemicals. The samples were characterized by means of impedance spectroscopy, fuel cell measurements, differential scanning calorimetry (DSC), thermogravimetry (TG) and X-ray diffraction. The electrical conductivity of the samples at room temperature showed a sensitive variation between 10{sup -6} and 10{sup -1} S/cm as the acid concentration was increased. Using the raw membranes as electrolytic separator in a fuel cell, voltages up to 726 mV were obtained. DSC thermograms showed a well-resolved step anomaly associated to a glass transition for samples with the highest acid concentrations: at about -130 C for the first set of samples and at about -120 C for the other sets, which indicates the amorphous character of the samples. TG traces confirmed that the membranes with higher acid concentrations have higher water contents and that the maximum rate of water removal is at about 50 C for all samples. X-ray spectra for the raw samples at room temperature show a large peak at about 2{theta} = 20 , which is smaller for the higher acid content samples and increases when the samples are annealed at 70 C, indicating that the amorphousness of PVAL complexes increases with the H{sub 3}PO{sub 2} content and drops with the water removal. The results, then, indicated the presence of a separate acid/water phase in the raw samples and an increasing polymer chain intervention in the ionic mobility as the samples are thermally treated. (orig.)

  11. The ATLAS SemiConductor Tracker operation and performance

    Science.gov (United States)

    Pater, J. R.

    2012-04-01

    The ATLAS SemiConductor Tracker (SCT) is a key precision tracking detector in the ATLAS experiment at CERN's Large Hadron Collider. The SCT is composed of 4088 planar p-in-n silicon micro-strip detectors. The signals from the strips are processed in the front-end ABCD3TA ASICs, which operate in binary readout mode; data are transferred to the off-detector readout electronics via optical fibres. The SCT was completed in 2007. An extensive commissioning phase followed, during which calibration data were collected and analysed to determine the noise performance of the system, and further performance parameters of the detector were determined using cosmic ray data, both with and without magnetic field. After the commissioning phase, the SCT was ready for the first LHC proton-proton collisions in December 2009. From the beginning of data taking, the completed SCT has been in very good shape with more than 99% of its 6.3 million strips operational; the detector is well timed-in and the operational channels are 99.9% efficient in data acquisition. The noise occupancy and hit efficiency are better than the design specifications. The detector geometry is monitored continuously with a laser-based alignment system and is stable to the few-micron level; the alignment accuracy as determined by tracks is near specification and improving as statistics increase. The sensor behaviour in the 2T solenoidal magnetic field has been studied by measuring the Lorentz angle. Radiation damage in the silicon is monitored by periodic measurements of the leakage current; these measurements are in reasonable agreement with predictions.

  12. Keeping an Eye on the Conductor: Neural Correlates of Visuo-motor Synchronization and Musical Experience

    Directory of Open Access Journals (Sweden)

    Kentaro eOno

    2015-04-01

    Full Text Available For orchestra musicians, synchronized playing under a conductor’s direction is necessary to achieve optimal performance. Previous studies using simple auditory/visual stimuli have reported cortico-subcortical networks underlying synchronization and that training improves the accuracy of synchronization. However, it is unclear whether people who played regularly under a conductor and non-musicians activate the same networks when synchronizing with a conductor’s gestures. We conducted a functional magnetic resonance imaging (fMRI experiment testing nonmusicians and musicians who regularly play music under a conductor. Participants were required to tap the rhythm they perceived from silent movies displaying either conductor’s gestures or a swinging metronome. Musicians performed tapping under a conductor with more precision than nonmusicians. Results from fMRI measurement showed greater activity in the anterior part of the left superior frontal gyrus (SFG in musicians with more frequent practice under a conductor. Conversely, tapping with the metronome did not show any difference between musicians and nonmusicians, indicating that the expertise effect in tapping under the conductor does not result in a general increase in tapping performance for musicians. These results suggest that orchestra musicians have developed an advanced ability to predict conductor’s next action from the gestures.

  13. Bending properties of different REBCO coated conductor tapes and Roebel cables at T = 77 K

    Science.gov (United States)

    Otten, Simon; Kario, Anna; Kling, Andrea; Goldacker, Wilfried

    2016-12-01

    Application of REBCO coated conductors in coils or cables involves deformation of the conductor in different modes, such as in-plane bending, out-of-plane bending and torsion. For example, the dipole magnet designs in the EuCARD-2 project require bending radii as low as 7.5 mm, inducing significant bending strain in the REBCO layer. In this paper, we investigate the effect of out-of-plane bending on the current-carrying properties of coated conductors from different manufacturers. The samples are manipulated by means of a Goldacker-type bending rig, which allows continuous bending at T = 77 K. By reversal to R=∞ after each bending step, the reversible strain effect is separated from irreversible degradation. All tested conductors are found to tolerate compressive bending to a radius of 6 mm with less than 5% irreversible degradation of the critical current. The magnitude of the reversible strain effect shows a large variation among the samples. The effect of out-of-plane bending on Roebel cables is investigated as well, and the results are compared to the bending characteristic of single conductors. The results show no detrimental effect of the cable assembly on the bending properties within the constraints of the test.

  14. In-field critical current property of IBAD/PLD coated conductors

    Science.gov (United States)

    Fujita, S.; Daibo, M.; Igarashi, M.; Kikutake, R.; Kakimoto, K.; Iijima, Y.; Itoh, M.; Saitoh, T.

    2014-05-01

    REBa2Cu3Oy, (RE : rare earth elements, RE123) coated conductors are expected to show high performance in superconducting applications, due to their high mechanical strength and high current density in magnetic fields. Fujikura has developed ion-beam-assisted-deposition (IBAD) and pulsed-laser-deposition (PLD) technique, and today we routinely manufacture coated conductors with length over 500 m and Ic over 500 A/cm-width at 77 K, self field. We have also been able to fabricate long conductors with higher Ic by thickening RE123 layer. Although Ic performances at 77 K, self field are important, but performances in magnetic fields at lower temperatures below 77 K are more important for coil applications. In this work, we evaluated coated conductors with thick RE123 layer in magnetic fields at low temperatures. All samples are fabricated with long length. We measured samples by four-probe transport method at wide temperature range from 77 K to 10 K by using cryo-cooled cryostat. A conductor with 5.5 μm thick RE123 exhibits high Ic values of 937 A/cm-width at 77 K, self field, 637 A/cm-width at 50 K, 5T and 976 A/cm-width at 40 K, 5T.

  15. Novel hybrid conductors based on doped ceria and BCY20 for ITSOFC applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Bin [Department of Chemical Engineering and Technology, Royal Institute of Technology (KTH), S-100 44, Stockholm (Sweden); Liu, Xiangrong [Goeta Technology Developer International, S-17160, Solna (Sweden); Schober, T. [IFF, Forschungszentrum Julich, Julich (Germany)

    2004-04-01

    Ceria-based composites have been previously developed as functional electrolytes for high performance ITSOFC applications. These composites display hybrid proton and oxygen ion conduction. To meet demands for more functional hybrid proton and oxygen ion conductors we developed further composite electrolyte materials containing a proton conductor, BaCe{sub 0.8}Y{sub 0.2}O{sub 3-{delta}} (BCY20), and an oxygen ion conductor, samarium doped ceria (SDC). The BCY20 and SDC composites were prepared based on composite technology using their starting powders produced via sol-gel and co-precipitation processes, respectively. Using the SDC-BCY20 composites as the electrolytes ITSOFCs were constructed using NiO-based composite anodes, silver-based cathodes. Applying hydrogen as the fuel, compressed air as the oxidant, the fuel cells were tested in the temperature region between 300 and 700C. The SDC-BCY20 electrolyte ITSOFCs reached a performance of 0.25 W/cm{sup 2} at 550C. Under a constant discharge water was observed both, on the anode and the cathode side, indicative of hybrid conduction based on proton and oxygen ion transport. Initial experimental results showed that combining a proton with an oxygen ion conductor forming a novel hybrid ion conductor with promising applications for ITSOFCs was successful.

  16. Measurements of the transverse resistance and eddy current losses in a cable-in-conduit conductor

    Science.gov (United States)

    Keilin, V. E.; Kovalev, I. A.; Kruglov, S. L.; Lelekhov, S. A.; Il'in, A. A.; Naumov, A. V.; Shcherbakov, V. I.; Shutov, K. A.

    2015-11-01

    In the case of plasma current interruption in tokamaks, the conductor of toroidial field (TF) coils experiences the action of a pulsed decreasing magnetic field (PDMF) parallel to the conductor's axis. To estimate the stability of a cable-in-conduit conductor against the PDMF, a new experimental method to study different types of losses is applied. This method exploits a high sensitivity of temperature and gas pressure to input energy in a closed volume. It allows one to measure hysteresis losses with a rather high accuracy (provided that the rate of change of the PDMF is low) and a sum of hysteresis losses and eddy current losses (when the rate of change of the PDMF is high). An experimental setup to measure the transverse (circumferential) resistance and losses has been developed at the National Research Centre Kurchatov Institute. A Russianmade Nb3Sn conductor intended for the TF coils of the International Thermonuclear Experimental Reactor is subjected to a PDMF with different amplitudes and characteristic times. The electromagnetic time constant and the transverse resistivity of the conductor are experimentally determined. The maximum temperature of strands under the action of the PDMF is calculated.

  17. Fragmented carbon nanotube macrofilms as adhesive conductors for lithium-ion batteries.

    Science.gov (United States)

    Cao, Zeyuan; Wei, Bingqing

    2014-03-25

    Polymer binders such as poly(vinylidene fluoride) (PVDF) and conductive additives such as carbon black (CB) are indispensable components for manufacturing battery electrodes in addition to active materials. The concept of adhesive conductors employing fragmented carbon nanotube macrofilms (FCNTs) is demonstrated by constructing composite electrodes with a typical active material, LiMn2O4. The adhesive FCNT conductors provide not only a high electrical conductivity but also a strong adhesive force, functioning simultaneously as both the conductive additives and the binder materials for lithium-ion batteries. Such composite electrodes exhibit superior high-rate and retention capabilities compared to the electrodes using a conventional binder (PVDF) and a conductive additive (CB). An in situ tribology method combining wear track imaging and force measurement is employed to evaluate the adhesion strength of the adhesive FCNT conductors. The adhesive FCNT conductors exhibit higher adhesion strength than PVDF. It has further been confirmed that the adhesive FCNT conductor can be used in both cathodes and anodes and is proved to be a competent substitute for polymer binders to maintain mechanical integrity and at the same time to provide electrical connectivity of active materials in the composite electrodes. The organic-solvent-free electrode manufacturing offers a promising strategy for the battery industry.

  18. Observation of quantum interference in molecular charge transport

    DEFF Research Database (Denmark)

    Guedon, Constant M.; Valkenier, Hennie; Markussen, Troels

    2012-01-01

    , phenomena such as giant magnetoresistance(5), Kondo effects(6) and conductance switching(7-11) have been observed in single molecules, and theorists have predicted that it should also be possible to observe quantum interference in molecular conductors(12-18), but until now all the evidence...

  19. Synthesis, Structure and Solid State Properties of Cyclohexanemethylamine Substituted Phenalenyl Based Molecular Conductor

    Directory of Open Access Journals (Sweden)

    Robert C. Haddon

    2012-05-01

    Full Text Available We report the preparation, crystallization and solid state characterization of a cyclohexanemethylamine substituted spirobiphenalenyl radical; in the solid state the compound is iso-structural with its dehydro-analog (benzylamine-substitued compound, and the molecules packed in a one-dimensional fashion that we refer to as a π-step stack. Neighboring molecules in the stack interact via the overlap of one pair of active (spin bearing carbon atoms per phenalenyl unit. The magnetic susceptibility measurement indicates that in the solid state the radical remains paramagnetic and the fraction of Curie spins is 0.75 per molecule. We use the analytical form of the Bonner-Fisher model for the S = 1/2 antiferromagnetic Heisenberg chain of isotropically interacting spins with intrachain spin coupling constant J = 6.3 cm−1, to fit the experimentally observed paramagnetism [χp (T] in the temperature range 4–330 K. The measured room temperature conductivity (σRT = 2.4 × 10–3 S/cm is comparable with that of the iso-structural benzyl radical, even though the calculated band dispersions are smaller than that of the unsaturated analog.

  20. Electron and phonon drag in thermoelectric transport through coherent molecular conductors

    DEFF Research Database (Denmark)

    Lü, Jing-Tao; Wang, Jian-Sheng; Hedegård, Per

    2016-01-01

    there are at least two phonon degrees of freedom. After deriving expressions for the linear drag coefficients, obeying the Onsager relation, we further investigate their effect on nonequilibrium transport. We show that the drag effect is closely related to two other phenomena: (1) adiabatic charge pumping through...

  1. Development of Low AC Loss TFA-MOD Coated Conductors

    Science.gov (United States)

    Katayama, K.; Machi, T.; Nakamura, T.; Takagi, Y.; Nakaoka, K.; Yoshizumi, M.; Izumi, T.; Shiohara, Y.

    TFA-MOD process is expected to be promising for future applications since it can produce high performance YBCO coated conductors (CCs) with low cost. Applying YBCO CCs to the power electric devices such as transformers and power cables, the reduction of alternating current (AC) loss for long wire is necessary. Multi-filamentation process, which is one of the most effective approaches for AC loss reduction, has been developed by the scribing process. We have developed the filamentation process using chemical etching. MOD derived CCs are, however, easily damaged in the chemical etching process due to existence of pores in a YBCO layer, resulting in critical current (Ic)-degradation and weak delamination strength. Consequently, it is difficult to scribe MOD derived CCs into 1mm-wide filaments for long length using the chemical etching process. Accordingly, we have studied a scribing process using an excimer laser without chemical etching. We defined P' value in this study as a function of irradiated laser power [J] divided by processing speed[m/s]. We studied relationship between the P' value and the results of scribing. It was found that we could scribe the C.C. with a sufficient depth in the condition of large P' value. Furthermore, we found that the Ic was degraded with further increase of the P' value. A 5 mm wide short sample was divided into 10 filaments by the excimer laser scribing process at the P' of 9[J/(m/s)]. The sample revealed reduction of the hysteresis loss down to 1/10 which could be expected from a theoretical prediction using the numbers of the filaments. Ic-degradation was suppressed as 28%, which was smaller than that of the scribed sample using chemical etching (Ic degradation was 38%). Subsequently, we applied the technique to a 100m long YBCO CC. The hysteresis loss of the 100m long MOD derived CC was reduced down to 1/10 (1/the number of filaments) after the multi-filamentation.

  2. High magnetic field studies of BEDT-TTF organic conductors

    Energy Technology Data Exchange (ETDEWEB)

    Honold, M.M

    1999-07-01

    This Thesis gives a detailed account of the high magnetic field properties of {alpha}-phase BEDT-TTF charge-transfer salts, with particular focus on the salts {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} and {alpha}-(BEDT-TTF){sub 2}TlHg(SCN){sub 4}. The existence of the bulk quantum Hall effect and its eventual destruction in the high-field limit is shown by a variety of experimental means, including magnetoresistance, magnetisation and Hall potential oscillation studies; the latter are based on a new technique specifically developed for this purpose. Chapter 1 introduces the concept of organic conductors and emphasises their potential as prototype systems of reduced dimensionality; in Chapter 2, the necessary physics and experimental techniques for their investigation are outlined. Following model calculations which suggested the possibility of the quantum Hall effect in {alpha}-phase BEDT-TTF salts, measurements of the Hall resistivity were carried out on {alpha}-(BEDT-TTF){sub 2}TlHg(SCN){sub 4} (described in Chapter 3). These exhibit a series of plateaux and represent the direct observation of the quantum Hall effect in a bulk material. Chapter 4 reports the discovery of an anomalous magnetotransport mode in the interplane resistance of {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} which involves the suppression and phase inversion of the Shubnikov-de Haas oscillations at low temperatures. This is interpreted as the action of a two-dimensional chiral Fermi liquid formed from the current-carrying edge states of each quantum Hall layer. Chapter 5 reports the first observation of magnetic breakdown in the high-field phase of {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4}, allowing an improved description of the high-field Fermi surface topology. These results are used to develop a new model for the nested low-field Fermi surface which can explain experimental evidence previously unaccounted for. Studies of the limiting behaviour of Hall potential oscillations in Chapter 6 show

  3. Electrical and Thermal Properties of Mixed Conductors and Superconductors

    Science.gov (United States)

    Thomas, Joyce Albritton

    1995-01-01

    , previously unreported chalcogenides were prepared by systematically varying the amount of Cu in the synthesis reactions. The conductivity and thermopower data for both rm K_2Cu _2CeS_4 and CsCuCeS_3 indicate non-metallic behavior which is directly related to the crystal structure. The range of varying behavior in the electrical and thermal properties of both mixed conductors and superconductors has been better identified using different material systems than could have been obtained from just examining a single material system.

  4. Modelling ac ripple currents in HTS coated conductors

    Science.gov (United States)

    Xu, Zhihan; Grilli, Francesco

    2015-10-01

    Dc transmission using high temperature superconducting (HTS) coated conductors (CCs) offers a promising solution to the globally growing demand for effective, reliable and economic transmission of green energy up to the gigawatt level over very long distances. The credible estimation of the losses and thereby the heat dissipation involved, where ac ripples (introduced in rectification/ac-dc conversion) are viewed as a potential source of notable contribution, is highly essential for the rational design of practical HTS dc transmission cables and corresponding cryogenic systems to fulfil this demand. Here we report a targeted modelling study into the ac losses in a HTS CC subject to dc and ac ripple currents simultaneously, by solving Maxwell’s equations using the finite element method (FEM) in the commercial software package COMSOL. It is observed that the instantaneous loss exhibits only one peak per cycle in the HTS CC subject to sinusoidal ripples, given that the amplitude of the ac ripples is smaller than approximately 20% of that of the dc current. This is a distinct contrast to the usual observation of two peaks per cycle in a HTS CC subject to ac currents only. The unique mechanism is also revealed, which is directly associated with the finding that, around any local minima of the applied ac ripples, the critical state of -J c is never reached at the edges of the HTS CC, as it should be according to the Bean model. When running further into the longer term, it is discovered that the ac ripple loss of the HTS CC in full-wave rectification decays monotonically, at a speed which is found to be insensitive to the frequency of the applied ripples within our targeted situations, to a relatively low level of approximately 1.38 × 10-4 W m-1 in around 1.7 s. Comparison between this level and other typical loss contributions in a HTS dc cable implies that ac ripple currents in HTS CCs should only be considered as a minor source of dissipation in superconducting dc

  5. Optimal Conductor Selection in Radial Distribution Systems for Productivity Improvement Using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Mahdi Mozaffari Legha

    2013-06-01

    Full Text Available Development of distribution systems result in higher system losses and poor voltage regulation. Consequently, an efficient and effective distribution system has become more urgent and important. Hence proper selection of conductors in the distribution system is important as it determines the current density and the resistance of the line. This paper examines the use of different evolutionary algorithms, genetic algorithm (GA, to optimal branch conductor selection in planning radial distribution systems with the objective to minimize the overall cost of annual energy losses and depreciation on the cost of conductors and reliability in order to improve productivity. Furthermore, The Backward-Forward sweep iterative method was adopted to solve the radial load flow analysis. Simulations are carried out on 69-bus radial distribution network using GA approach in order to show the accuracy as well as the efficiency of the proposed solution technique.

  6. Research status of novel La2Mo2O9-based oxide-ion conductors

    Institute of Scientific and Technical Information of China (English)

    FANG Qianfeng; WANG Xianping; CHENG Zhijun; ZHANG Guoguang

    2007-01-01

    La2Mo2O9-based oxide-ion conductors have attracted more and more attention since the high ionic con-ductivity was reported in 2000 by Lacorre et al.in this kind of material.In this paper the recent investigation on the novel La2Mo2O9-based oxide-ion conductors is reviewed.It is focused on the structure and phase transition,oxide-ion conductivity,mechanism of oxygen vacancy diffusion,chem-ical stability and thermal expansion coefficient in the pure and doped La2Mo2O9 samples.It is pointed out that the La2Mo2O9-based oxide-ion conductors could be possibly applied in the fields such as solid oxide fuel cells,oxygen sensors and oxygen permeable membranes.

  7. Experimental study of the nonlinear diffusion of a magnetic field and skin explosion of cylindrical conductors

    Energy Technology Data Exchange (ETDEWEB)

    Chaikovsky, S. A.; Datsko, I. M.; Labetskaya, N. A.; Rybka, D. V.; Ratakhin, N. A. [Institute of High Current Electronics, SB, RAN, Tomsk (Russian Federation); Oreshkin, V. I. [Institute of High Current Electronics, SB, RAN, Tomsk (Russian Federation); Tomsk Polytechnic University, Tomsk (Russian Federation)

    2015-11-15

    The paper presents the results of an experimental study of the skin explosion of cylindrical conductors of diameter 1–3 mm (copper, aluminum, titanium, steel 3, and stainless steel) at a peak magnetic field of 200–600 T. The experiments were carried out on the MIG pulsed power generator at a current of up to 2.5 MA and a current rise time of 100 ns. The surface explosion of a conductor was identified by the appearance of a flash of extreme ultraviolet radiation. A minimum magnetic induction has been determined below which no plasma is generated at the conductor surface. For copper, aluminum, steel 3, titanium, and stainless steel, the minimum magnetic induction has been estimated to be (to within 10%) 375, 270, 280, 220, and 245 T, respectively.

  8. Printable elastic conductors with a high conductivity for electronic textile applications

    Science.gov (United States)

    Matsuhisa, Naoji; Kaltenbrunner, Martin; Yokota, Tomoyuki; Jinno, Hiroaki; Kuribara, Kazunori; Sekitani, Tsuyoshi; Someya, Takao

    2015-06-01

    The development of advanced flexible large-area electronics such as flexible displays and sensors will thrive on engineered functional ink formulations for printed electronics where the spontaneous arrangement of molecules aids the printing processes. Here we report a printable elastic conductor with a high initial conductivity of 738 S cm-1 and a record high conductivity of 182 S cm-1 when stretched to 215% strain. The elastic conductor ink is comprised of Ag flakes, a fluorine rubber and a fluorine surfactant. The fluorine surfactant constitutes a key component which directs the formation of surface-localized conductive networks in the printed elastic conductor, leading to a high conductivity and stretchability. We demonstrate the feasibility of our inks by fabricating a stretchable organic transistor active matrix on a rubbery stretchability-gradient substrate with unimpaired functionality when stretched to 110%, and a wearable electromyogram sensor printed onto a textile garment.

  9. An antireflection transparent conductor with ultralow optical loss (<2 %) and electrical resistance (<6 Ω sq-1)

    Science.gov (United States)

    Maniyara, Rinu Abraham; Mkhitaryan, Vahagn K.; Chen, Tong Lai; Ghosh, Dhriti Sundar; Pruneri, Valerio

    2016-12-01

    Transparent conductors are essential in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and solar cells. Here we demonstrate a transparent conductor with optical loss of ~1.6%, that is, even lower than that of single-layer graphene (2.3%), and transmission higher than 98% over the visible wavelength range. This was possible by an optimized antireflection design consisting in applying Al-doped ZnO and TiO2 layers with precise thicknesses to a highly conductive Ag ultrathin film. The proposed multilayer structure also possesses a low electrical resistance (5.75 Ω sq-1), a figure of merit four times larger than that of indium tin oxide, the most widely used transparent conductor today, and, contrary to it, is mechanically flexible and room temperature deposited. To assess the application potentials, transparent shielding of radiofrequency and microwave interference signals with ~30 dB attenuation up to 18 GHz was achieved.

  10. A comparison of graphene, superconductors and metals as conductors for metamaterials and plasmonics

    Energy Technology Data Exchange (ETDEWEB)

    Tassin, Philippe; Koschny, Thomas; Kafesaki, Maria; Soukoulis, Costas

    2012-03-30

    Recent advancements in metamaterials and plasmonics have promised a number of exciting applications, in particular at terahertz and optical frequencies. Unfortunately, the noble metals used in these photonic structures are not particularly good conductors at high frequencies, resulting in significant dissipative loss. Here, we address the question of what is a good conductor for metamaterials and plasmonics. For resonant metamaterials, we develop a figure-of-merit for conductors that allows for a straightforward classification of conducting materials according to the resulting dissipative loss in the metamaterial. Application of our method predicts that graphene and high-T{sub c} superconductors are not viable alternatives for metals in metamaterials. We also provide an overview of a number of transition metals, alkali metals and transparent conducting oxides. For plasmonic systems, we predict that graphene and high-T{sub c} superconductors cannot outperform gold as a platform for surface plasmon polaritons, because graphene has a smaller propagation length-to-wavelength ratio.

  11. NEW APPROACHES: Students' understanding of the transfer of charge between conductors

    Science.gov (United States)

    Guruswamy, Chitra; Somers, Mark D.; Hussey, R. G.

    1997-03-01

    This paper describes an investigation into students' understanding of the transfer of charge between two charged conductors. The research is based on interviews conducted with students in an algebra and trigonometry based physics course and on written tests administered both before and after instruction. Results from two tasks are reported, both of which involve a pair of identical conductors that are given an initial charge, are made to touch each other and are then separated. The test was also administered as a post test to other populations at the pre-college and college levels. It was found that a considerable number of students from the eighth grader to the college student in an advanced physics course were unable to predict the transfer of charge correctly from one conductor to another. Implications for instruction are also discussed.

  12. Algorithm for detection of the broken phase conductor in the radial networks

    Directory of Open Access Journals (Sweden)

    Ostojić Mladen M.

    2016-01-01

    Full Text Available The paper presents an algorithm for a directional relay to be used for a detection of the broken phase conductor in the radial networks. The algorithm would use synchronized voltages, measured at the beginning and at the end of the line, as input signals. During the process, the measured voltages would be phase-compared. On the basis of the normalized energy, the direction of the phase conductor, with a broken point, would be detected. Software tool Matlab/Simulink package has developed a radial network model which simulates the broken phase conductor. The simulations generated required input signals by which the algorithm was tested. Development of the algorithm along with the formation of the simulation model and the test results of the proposed algorithm are presented in this paper.

  13. Status of high temperature superconductor based magnets and the conductors they depend upon

    CERN Document Server

    Schwartz, J; Chan, W K; Gou, X F; Liu, X T; Phillips, M; Le, Q V; Naderi, G; Turenne, M; Ye, L

    2011-01-01

    This paper reviews the status of high temperature superconductors for high field magnets for future devices such as a high energy LHC or a muon collider. Some of the primary challenges faced for the implementation of systems are discussed. Two conductor technologies, Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ and YBa$_2$Cu$_3$O$_{7-\\delta}$, have emerged as high field conductor options, but their relative advantages and disadvantages for high field magnets are quite different. These are reviewed from an engineering perspective, including coil manufacturing, electromechanical behaviour and quench behaviour. Lastly, the important roles of "system pull" upon conductor and magnet technology development, and of interactions between the materials and magnet communities for accelerating development, are discussed.

  14. Insulated conductor temperature limited heater for subsurface heating coupled in a three-phase WYE configuration

    Energy Technology Data Exchange (ETDEWEB)

    Vinegar, Harold J. (Bellaire, TX); Sandberg, Chester Ledlie (Palo Alto, CA)

    2010-11-09

    A heating system for a subsurface formation is described. The heating system includes a first heater, a second heater, and a third heater placed in an opening in the subsurface formation. Each heater includes: an electrical conductor; an insulation layer at least partially surrounding the electrical conductor; and an electrically conductive sheath at least partially surrounding the insulation layer. The electrical conductor is electrically coupled to the sheath at a lower end portion of the heater. The lower end portion is the portion of the heater distal from a surface of the opening. The first heater, the second heater, and the third heater are electrically coupled at the lower end portions of the heaters. The first heater, the second heater, and the third heater are configured to be electrically coupled in a three-phase wye configuration.

  15. Progress of long coated conductors fabrication with fluorine-free CSD method at SWJTU

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Y., E-mail: yzhao@swjtu.edu.cn [Key Lab of Advanced Materials Technologies, Key Lab of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education), Superconductivity and New Energy Center (SNEC), Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia); Wang, W.T.; Lei, M.; Pu, M.H.; Zhang, Y. [Key Lab of Advanced Materials Technologies, Key Lab of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education), Superconductivity and New Energy Center (SNEC), Southwest Jiaotong University, Chengdu 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia)

    2013-10-15

    Highlights: • Recent progress on the long coated conductors fabrication by F-free CSD method is presented. • Single buffer and partial-melting technology and slot-die coating methods have been developed. • Reel-to-reel facilities for continuous process have been achieved. -- Abstract: Recent progress on the fabrication of long high-T{sub c} superconducting coated conductors with a fluorine-free chemical solution deposition (CSD) method is presented. Developments including such novel methods as single buffer technology, partial-melting process on YBa{sub 2}Cu{sub 3}O{sub 7} (YBCO), slot-die coating and drying; reel-to-reel facilities for continuous process have been achieved in the effort on high-T{sub c} superconducting coated conductors at SWJTU, which form a comprehensive technology to fabricate long coated tapes with high performances.

  16. Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, M P; Ong, M M; Brown, C G; Speer, R D

    2011-07-20

    It is often necessary to protect sensitive electrical equipment from pulsed electric and magnetic fields. To accomplish this electromagnetic shielding structures similar to Faraday Cages are often implemented. If the equipment is inside a facility that has been reinforced with rebar, the rebar can be used as part of a lighting protection system. Unfortunately, such shields are not perfect and allow electromagnetic fields to be created inside due to discontinuities in the structure, penetrations, and finite conductivity of the shield. In order to perform an analysis of such a structure it is important to first determine the effect of the finite impedance of the conductors used in the shield. In this paper we will discuss the impedances of different cylindrical conductors in the time domain. For a time varying pulse the currents created in the conductor will have different spectral components, which will affect the current density due to skin effects. Many construction materials use iron and different types of steels that have a nonlinear permeability. The nonlinear material can have an effect on the impedance of the conductor depending on the B-H curve. Although closed form solutions exist for the impedances of cylindrical conductors made of linear materials, computational techniques are needed for nonlinear materials. Simulations of such impedances are often technically challenging due to the need for a computational mesh to be able to resolve the skin depths for the different spectral components in the pulse. The results of such simulations in the time domain will be shown and used to determine the impedances of cylindrical conductors for lightning current pulses that have low frequency content.

  17. Tension optimization of the conductor-and-support cable elements during stranding process

    Directory of Open Access Journals (Sweden)

    I.M. Chayun

    2016-12-01

    Full Text Available Steel lifting ropes, cables and other similar products are rod statically undeterminable prestressed structures. Preliminary deformations of their elements (wires are caused by their manufacturing technology. Wires suffer stretching, bending with torsion in a stage of elastoplastic deformation. In this work the mechanic-mathematical model of residual forces determination in the wires of polymetallic conductor-and-support cable is offered. Aim: The aim of the work is studying of the mechanical and mathematical model defining residual forces in the wires of conductor-and-support cable and also the optimization of parameters of a twist by the criterion of residual forces lack after production process finishing. Materials and methods: The method developed by the authors earlier to the study the strain-stressed state of twisted wire products off-loading from technological internal forces has been applied to assess the impact of the approximate value of the longitudinal stiffness of the product. In this paper, each wire is considered as an element of the product individually. This is necessary to investigate the impact of uneven wire tensions on defects of conductor-and-support cable (out-of-straight in a free state and stripping-down. Results: On the basis of the conducted deformation studies of conductor-and-support cable during off-loading process from twist tension of its elements the dependencies of residual forces on the level and interrelation of elements tension has been determined. The condition of ensuring of zero residual forces in the wires of conductor-and-support cable after production is formulated. It was found that calculated values of residual forces are almost identical when using of the approximate and exact values of longitudinal stiffness of conductor-and-support cable.

  18. The Conductor As Visual Guide: Gesture and Perception of Musical Content.

    Science.gov (United States)

    Kumar, Anita B; Morrison, Steven J

    2016-01-01

    Ensemble conductors are often described as embodying the music. Researchers have determined that expressive gestures affect viewers' perceptions of conducted ensemble performances. This effect may be due, in part, to conductor gesture delineating and amplifying specific expressive aspects of music performances. The purpose of the present study was to determine if conductor gesture affected observers' focus of attention to contrasting aspects of ensemble performances. Audio recordings of two different music excerpts featuring two-part counterpoint (an ostinato paired with a lyric melody, and long chord tones paired with rhythmic interjections) were paired with video of two conductors. Each conductor used gesture appropriate to one or the other musical element (e.g., connected and flowing or detached and crisp) for a total of sixteen videos. Musician participants evaluated 8 of the excerpts for Articulation, Rhythm, Style, and Phrasing using four 10-point differential scales anchored by descriptive terms (e.g., disconnected to connected, and angular to flowing.) Results indicated a relationship between gesture and listeners' evaluations of musical content. Listeners appear to be sensitive to the manner in which a conductor's gesture delineates musical lines, particularly as an indication of overall articulation and style. This effect was observed for the lyric melody and ostinato excerpt, but not for the chords and interjections excerpt. Therefore, this effect appears to be mitigated by the congruence of gesture to preconceptions of the importance of melodic over rhythmic material, of certain instrument timbres over others, and of length between onsets of active material. These results add to a body of literature that supports the importance of the visual component in the multimodal experience of music performance.

  19. Current Sharing Temperature Test and Simulation with GANDALF Code for ITER PF2 Conductor Sample%Current Sharing Temperature Test and Simulation with GANDALF Code for ITER PF2 Conductor Sample

    Institute of Scientific and Technical Information of China (English)

    李少磊; 武玉; 刘勃; 翁佩德

    2011-01-01

    Cable-in-conduit conductor (CICC) conductor sample of the PF2 coil for ITER was tested in the SULTAN facility. According to the test results, the CICC conductor sample exhibited a stable performance regarding the current sharing temperature. Under the typical operational conditions of a current of 45 kA, a magnetic field of 4 T and a temperature of 5 K for PF2, the test result for the conductor current sharing temperature is 6.71 K, with a temperature margin of 1.71 K. For a comparison thermal-hydraulic analysis of the PF2 conductor was carried out using GANDALF code in a 1-D model, and the result is consistent with the test one.

  20. The physics of positively biased conductors surrounded by dielectrics in contact with a plasma

    Science.gov (United States)

    Hastings, Daniel E.; Chang, Patrick

    1989-01-01

    The physics of a positively biased conductor surrounded by dielectrics in contact with plasma is investigated. It is shown that because of the presence of secondary emission from the surrounding dielectrics, the voltage of the surfaces near the conductor has three solutions. The high- and low-voltage solutions are stable, while the intermediate-voltage solution is unstable. This theory is applied to explain the snapover effect observed on high-voltage solar arrays that involve the use of highly biased surfaces in contact with the space environment.