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Sample records for electrical conductivity relaxation

  1. Measuring oxygen surface exchange kinetics on mixed-conducting composites by electrical conductivity relaxation

    NARCIS (Netherlands)

    Hu, Bobing; Wang, Yunlong; Zhu, Zhuoying; Xia, Changrong; Bouwmeester, Henricus J.M.

    2015-01-01

    The oxygen release kinetics of mixed-conducting Sr2Fe1.5Mo0.5O6 d–Sm0.2Ce0.8O2 d (SFM–SDC) dualphase composites has been investigated, at 750 C, as a function of the SDC phase volume fraction using electrical conductivity relaxation (ECR) under reducing atmospheres, extending our previous work on

  2. Oxygen exchange and diffusion coefficients of strontium-doped lanthanum ferrites by electrical conductivity relaxation

    NARCIS (Netherlands)

    ten Elshof, Johan E.; Lankhorst, M.H.R.; Lankhorst, M.H.R.; Bouwmeester, Henricus J.M.

    1997-01-01

    Electrical conductivity relaxation experiments were performed on thin specimens of La1–xSrxFeO3–delta (x = 0.1, 0.4) at oxygen partial pressures pO2 = 10–5 – 1 bar in the temperature range 923 to 1223 K. The transient response of the electrical conductivity after a sudden change of the ambient

  3. Correlation of carrier localization with relaxation time distribution and electrical conductivity relaxation in silver-nanoparticle-embedded moderately doped polypyrrole nanostructures

    Science.gov (United States)

    Biswas, Swarup; Dutta, Bula; Bhattacharya, Subhratanu

    2014-02-01

    The electrical conductivity relaxation in moderately doped polypyrrole and its nanocomposites reinforced with different proportion of silver nanoparticles was investigated in both frequency and time domain. An analytical distribution function of relaxation times is constructed from the results obtained in the frequency domain formalism and is used to evaluate the Kohlrausch-Williams-Watts (KWW) type decay function in the time domain. The thermal evolution of different relaxation parameters was analyzed. The temperature-dependent dc electrical conductivity, estimated from the average conductivity relaxation time is observed to depend strongly on the nanoparticle loading and follows Mott three-dimensional variable range hopping (VRH) conduction mechanism. The extent of charge carrier localization calculated from the VRH mechanism is well correlated to the evidences obtained from the structural characterizations of different nanostructured samples.

  4. Electrical Conductivity, Relaxation and the Glass Transition: A New Look at a Familiar Phenomenon

    Science.gov (United States)

    Angel, Paul W.; Cooper, Alfred R.; DeGuire, Mark R.

    1996-01-01

    Annealed samples from a single melt of a 10 mol% K2O-90SiO2 glass were reheated to temperatures ranging from 450 to 800 C, held isothermally for 20 min, and then quenched in either air or a silicon oil bath. The complex impedance of both the annealed and quenched samples was measured as a function of temperature from 120 to 250 C using ac impedance spectroscopy from 1 Hz to 1 MHz. The dc conductivity, sigma(sub dc), was measured from the low frequency intercept of depressed semicircle fits to the complex impedance data. When the sigma(sub dc) at 150 C was plotted against soak temperature, the results fell into three separate regions that are explained in terms of the glass structural relaxation time, tau(sub S). This sigma(sub dc) plot provides a new way to look the glass transition range, Delta T(sub r). In addition, sigma(sub dc) was measured for different soak times at 550 C, from which an average relaxation time of 7.3 min was calculated. It was found that the size and position of the Delta T(sub r) is controlled by both the soak time and cooling rate.

  5. Electrical conduction and dielectric relaxation in p-type PVA/CuI polymer composite

    Directory of Open Access Journals (Sweden)

    M.H. Makled

    2013-11-01

    Full Text Available PVA/CuI polymer composite samples have been prepared and subjected to characterizations using FT-IR spectroscopy, DSC analysis, ac spectroscopy and dc conduction. The FT-IR spectral analysis shows remarkable variation of the absorption peak positions whereas DSC illustrates a little decrease of both glass transition temperature, Tg, and crystallization fraction, χ, with increasing CuI concentration. An increase of dc conductivity for PVA/CuI nano composite by increasing CuI concentration is recoded up to 15 wt%, besides it obeys Arhenuis plot with an activation energy in the range 0.54–1.32 eV. The frequency dependence of ac conductivity showed power law with an exponent 0.33 < s < 0.69 which predicts hopping conduction mechanism. The frequency dependence of both dielectric permittivity and dielectric loss obeys Debye dispersion relations in wide range of temperatures and frequency. Significant values of dipole relaxation time obtained which are thermally activated with activation energies in the range 0.33–0.87 eV. A significant value of hopping distance in the range 3.4–1.2 nm is estimated in agreement with the value of Bohr radius of the exciton.

  6. Untangling surface oxygen exchange effects in YBa2Cu3O6+x thin films by electrical conductivity relaxation.

    Science.gov (United States)

    Cayado, P; Sánchez-Valdés, C F; Stangl, A; Coll, M; Roura, P; Palau, A; Puig, T; Obradors, X

    2017-05-31

    The kinetics of oxygen incorporation (in-diffusion process) and excorporation (out-diffusion process), in YBa 2 Cu 3 O 6+x (YBCO) epitaxial thin films prepared using the chemical solution deposition (CSD) methodology by the trifluoroacetate route, was investigated by electrical conductivity relaxation measurements. We show that the oxygenation kinetics of YBCO films is limited by the surface exchange process of oxygen molecules prior to bulk diffusion into the films. The analysis of the temperature and oxygen partial pressure influence on the oxygenation kinetics has drawn a consistent picture of the oxygen surface exchange process enabling us to define the most likely rate determining step. We have also established a strategy to accelerate the oxygenation kinetics at low temperatures based on the catalytic influence of Ag coatings thus allowing us to decrease the oxygenation temperature in the YBCO thin films.

  7. Electrical Conductivity.

    Science.gov (United States)

    Hershey, David R.; Sand, Susan

    1993-01-01

    Explains how electrical conductivity (EC) can be used to measure ion concentration in solutions. Describes instrumentation for the measurement, temperature dependence and EC, and the EC of common substances. (PR)

  8. Non-Arrhenius conductivity in the fast ionic conductor Li0.5La0.5TiO3: Reconciling spin-lattice and electrical-conductivity relaxations

    International Nuclear Information System (INIS)

    Leon, C.; Santamaria, J.; Paris, M.A.; Sanz, J.; Ibarra, J.; Torres, L.M.

    1997-01-01

    Nuclear magnetic resonance and electrical conductivity measurements are conducted to study the dynamics of the ionic diffusion process in the crystalline ionic conductor Li 0.5 La 0.5 TiO 3 . dc conductivity shows a non-Arrhenius temperature dependence, similar to the one recently reported for some ionic conducting glasses. Spin-lattice and conductivity relaxations are analyzed in the same frequency and temperature range in terms of the non-Arrhenius dependence of the correlation time. Both relaxations are then described using a single correlation function of the form f(t)=exp(-(t/τ) β ), with β=0.4 over the whole temperature range. copyright 1997 The American Physical Society

  9. Electrically conductive cellulose composite

    Science.gov (United States)

    Evans, Barbara R.; O'Neill, Hugh M.; Woodward, Jonathan

    2010-05-04

    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  10. AC electrical conductivity and dielectric relaxation studies on n-type organic thin films of N, N‧-Dimethyl-3,4,9,10-perylenedicarboximide (DMPDC)

    Science.gov (United States)

    Qashou, Saleem I.; Darwish, A. A. A.; Rashad, M.; Khattari, Z.

    2017-11-01

    Both Alternating current (AC) conductivity and dielectric behavior of n-type organic thin films of N, N‧-Dimethyl-3,4,9,10-perylenedicarboximide (DMPDC) have been investigated. Fourier transformation infrared (FTIR) spectroscopy is used for identifying both powder and film bonds which confirm that there are no observed changes in the bonds between the DMPDC powder and evaporated films. The dependence of AC conductivity on the temperature for DMPDC evaporated films was explained by the correlated barrier hopping (CBH) model. The calculated barrier height using CBH model shows a decreasing behavior with increasing temperature. The mechanism of dielectric relaxation was interpreted on the basis of the modulus of the complex dielectric. The calculated activation energy of the relaxation process was found to be 0.055 eV.

  11. Electrically conductive composite material

    Science.gov (United States)

    Clough, Roger L.; Sylwester, Alan P.

    1989-01-01

    An electrically conductive composite material is disclosed which comprises a conductive open-celled, low density, microcellular carbon foam filled with a non-conductive polymer or resin. The composite material is prepared in a two-step process consisting of first preparing the microcellular carbon foam from a carbonizable polymer or copolymer using a phase separation process, then filling the carbon foam with the desired non-conductive polymer or resin. The electrically conductive composites of the present invention has a uniform and consistant pattern of filler distribution, and as a result is superior over prior art materials when used in battery components, electrodes, and the like.

  12. Electrically conductive material

    Science.gov (United States)

    Singh, J.P.; Bosak, A.L.; McPheeters, C.C.; Dees, D.W.

    1993-09-07

    An electrically conductive material is described for use in solid oxide fuel cells, electrochemical sensors for combustion exhaust, and various other applications possesses increased fracture toughness over available materials, while affording the same electrical conductivity. One embodiment of the sintered electrically conductive material consists essentially of cubic ZrO[sub 2] as a matrix and 6-19 wt. % monoclinic ZrO[sub 2] formed from particles having an average size equal to or greater than about 0.23 microns. Another embodiment of the electrically conductive material consists essentially at cubic ZrO[sub 2] as a matrix and 10-30 wt. % partially stabilized zirconia (PSZ) formed from particles having an average size of approximately 3 microns. 8 figures.

  13. Surface exchange kinetics and chemical diffusivities of BaZr{sub 0.2}Ce{sub 0.65}Y{sub 0.15}O{sub 3−δ} by electrical conductivity relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Dae-Kwang; Jeon, Sang-Yun; Singh, Bhupendra [Ionics Lab, School of Materials Science and Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwang-Ju 500-757 (Korea, Republic of); Park, Jun-Young [Department of Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Song, Sun-Ju, E-mail: song@chonnam.ac.kr [Ionics Lab, School of Materials Science and Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwang-Ju 500-757 (Korea, Republic of)

    2014-10-15

    Highlights: • Electrical conductivity relaxation in BaCe{sub 0.65}Zr{sub 0.2}Y{sub 0.15}O{sub 3−δ} was monitored. • Monotonic relaxation behavior was observed during oxidation/reduction. • Nonmonotonic twofold relaxation behavior was observed during hydration/dehydration. • Surface exchange coefficients and diffusivities of O and H were calculated. - Abstract: Perovskite-type oxide BaCe{sub 0.65}Zr{sub 0.2}Y{sub 0.15}O{sub 3−δ} (BCZY2015) was synthesized by a solid state reaction method. BCZY2015 samples were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The time dependent variation in electrical conductivity of BCZY2015 was monitored during the oxidation/reduction in oxygen partial pressure (pO{sub 2}) range of −2.28 ⩽ log (pO{sub 2}/atm) ⩽ −0.68 at a fixed water vapor pressure (pH{sub 2}O), and during the hydration/dehydration in −3.15 ⩽ log (pH{sub 2}O/atm) ⩽ −2.35 range in air. The electrical conductivity showed a monotonic relaxation behavior by the ambipolar diffusion of V{sub o}{sup ··} and OH{sub o}{sup ·} during the oxidation/reduction and the relaxation process was governed by the diffusivity of oxygen (D-tilde{sub vO}). On the other hand, during the hydration/dehydration process, a non-monotonic twofold relaxation behavior was observed due to the decoupled diffusion of H and O components with the mediation of holes, and the conductivity relaxation process was governed by the diffusivities of both H (D-tilde{sub iH}) and O (D-tlde{sub vH}). The values of surface exchange coefficients and diffusivities of oxygen and hydrogen were calculated from Fick’s second law by the nonlinear least squares fitting of the conductivity data, as proposed by Yoo et al. (2008)

  14. Structural relaxation and thermal conductivity coefficient of liquids

    International Nuclear Information System (INIS)

    Abdurasulov, A.

    1992-01-01

    Present article is devoted to structural relaxation and thermal conductivity coefficient of liquids. The thermoelastic properties of liquids were studied taking into account the contribution of translational and structural relaxation. The results of determination of dynamic coefficient of thermal conductivity of liquids taking into account the contribution of translational and structural relaxation are presented.

  15. Electrically Conductive Epoxy Adhesives

    Directory of Open Access Journals (Sweden)

    Lan Bai

    2011-02-01

    Full Text Available Conductive adhesives are widely used in electronic packaging applications such as die attachment and solderless interconnections, component repair, display interconnections, and heat dissipation. The effects of film thickness as functions of filler volume fraction, conductive filler size, shape, as well as uncured adhesive matrix viscosity on the electrical conduction behavior of epoxy-based adhesives are presented in this work. For this purpose, epoxy-based adhesives were prepared using conductive fillers of different size, shape, and types, including Ni powder, flakes, and filaments, Ag powder, and Cu powder. The filaments were 20 μm in diameter, and 160 or 260 μm in length. HCl and H3PO4 acid solutions were used to etch and remove the surface oxide layers from the fillers. The plane resistance of filled adhesive films was measured using the four-point method. In all cases of conductive filler addition, the planar resistivity levels for the composite adhesive films increased when the film thickness was reduced. The shape of resistivity-thickness curves was negative exponential decaying type and was modeled using a mathematical relation. The relationships between the conductive film resistivities and the filler volume fractions were also derived mathematically based on the experimental data. Thus, the effects of surface treatment of filler particles, the type, size, shape of fillers, and the uncured epoxy viscosity could be included empirically by using these mathematical relations based on the experimental data. By utilizing the relations we proposed to model thickness-dependent and volume fraction-dependent conduction behaviors separately, we were able to describe the combined and coupled volume fraction-film thickness relationship mathematically based on our experimental data.

  16. Relaxation behavior of ion conducting glasses

    International Nuclear Information System (INIS)

    Bunde, A.; Dieterich, W.; Maass, P.; Meyer, M.

    1997-01-01

    We investigate by Monte Carlo simulations the diffusion of ions in an energetically disordered lattice, where the Coulomb interaction between the mobile ions is explicitly taken into account. We show that the combined effect of Coulomb interaction and disorder can account for the ionic ac-conductivity in glasses and the recently discovered non-Arrhenius behavior of the dc-conductivity in glassy fast ionic conductors. Our results suggest that glassy ionic conductors can be optimized by lowering the strength of the energetic disorder but that the ionic interaction effects set an upper bound for the conductivity at high temperatures. (author)

  17. Electrical Conduction and Superconductivity

    Indian Academy of Sciences (India)

    When an electric field is applied, this electron can be lifted to this higher energy ... By such a virtual process two electrons .... using superconducting coils has come to be a reality. ... nance imaging techniques used in medical diagnostics. Com ...

  18. Electric modulus approach to the analysis of electric relaxation in highly conducting (Na{sub 0.75}Bi{sub 0.25})(Mn{sub 0.25}Nb{sub 0.75})O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Molak, A; Paluch, M; Pawlus, S; Klimontko, J; Ujma, Z; Gruszka, I [Institute of Physics, University of Silesia, ul. Uniwersytecka 4, PL-40-007 Katowice (Poland)

    2005-05-07

    Broadband dielectric spectroscopy is applied to investigate the electrical properties of disordered perovskite-like ceramics in a wide temperature range. From the x-ray diffraction analysis it was found that the newly obtained (Na{sub 0.75}Bi{sub 0.25}) (Mn{sub 0.25}Nb{sub 0.75})O{sub 3} ceramics consist of two chemically different phases. The major perovskite one has an orthorhombic structure described by the Pbcm space group (No 57, in yxz setting). The minor phase shows an orthorhombic symmetry, all-face-centred lattice F, with the lattice parameters a = 10.797(4) A, b = 7.601(3) A and c = 7.691(3) A. The electric modulus M{sup *} formalism used in the analysis enabled us to distinguish and separate the relaxation processes, dominated by marked conductivity in the {epsilon}{sup *}({omega}) representation. In the ceramics studied, the relaxation times are thermally activated and the dipole process has a clearly non-Debye behaviour. The relaxation process described with the use of the activation energy of approximately 0.4 eV and the characteristic relaxation time, {tau}{sub 0} = 1 x 10{sup -11} s, was found to be related to oxygen vacancies. The low frequency relaxation shows Debye behaviour with a slightly lower activation energy and a longer characteristic time.

  19. Electrically conductive anodized aluminum coatings

    Science.gov (United States)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  20. Fundamentals of ionic conductivity relaxation gained from study of procaine hydrochloride and procainamide hydrochloride at ambient and elevated pressure.

    Science.gov (United States)

    Wojnarowska, Z; Swiety-Pospiech, A; Grzybowska, K; Hawelek, L; Paluch, M; Ngai, K L

    2012-04-28

    The pharmaceuticals, procaine hydrochloride and procainamide hydrochloride, are glass-forming as well as ionically conducting materials. We have made dielectric measurements at ambient and elevated pressures to characterize the dynamics of the ion conductivity relaxation in these pharmaceuticals, and calorimetric measurements for the structural relaxation. Perhaps due to their special chemical and physical structures, novel features are found in the ionic conductivity relaxation of these pharmaceuticals. Data of conductivity relaxation in most ionic conductors when represented by the electric loss modulus usually show a single resolved peak in the electric modulus loss M(")(f) spectra. However, in procaine hydrochloride and procainamide hydrochloride we find in addition another resolved loss peak at higher frequencies over a temperature range spanning across T(g). The situation is analogous to many non-ionic glass-formers showing the presence of the structural α-relaxation together with the Johari-Goldstein (JG) β-relaxation. Naturally the analogy leads us to name the slower and faster processes resolved in procaine hydrochloride and procainamide hydrochloride as the primary α-conductivity relaxation and the secondary β-conductivity relaxation, respectively. The analogy of the β-conductivity relaxation in procaine HCl and procainamide HCl with JG β-relaxation in non-ionic glass-formers goes further by the finding that the β-conductivity is strongly related to the α-conductivity relaxation at temperatures above and below T(g). At elevated pressure but compensated by raising temperature to maintain α-conductivity relaxation time constant, the data show invariance of the ratio between the β- and the α-conductivity relaxation times to changes of thermodynamic condition. This property indicates that the β-conductivity relaxation has fundamental importance and is indispensable as the precursor of the α-conductivity relaxation, analogous to the relation found

  1. Electrically Conductive Anodized Aluminum Surfaces

    Science.gov (United States)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In

  2. Dielectric relaxation of glass particles with conductive nano-coatings

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Shahid [Applied Technologies Department, QinetiQ Limited, Cody Technology Park, Farnborough, Hampshire, GU14 0LX (United Kingdom)

    2009-03-21

    This research focuses on the dielectric properties of particles consisting of glass cores with nanometre conductive coatings. The effects of the core glass particle shape (sphere, flake and fibre) and size are investigated for different coating characteristics over the frequency range 0.5-18 GHz. Experimental results for the coated glass particle combinations show the existence of a dielectric loss peak. This feature is associated with interfacial relaxation between the insulating core glass particle and the nanoscale conductive coating. The relaxation mechanism provides enhanced loss that is not observed in conventional solid metal particle composites. The results are fitted to a model, which shows that the relaxation frequency increases with increasing coating conductivity and thickness, with additional parameters identified for further particle optimizations.

  3. Study of conduction mechanisms and relaxation processes in NiCl2-PVA composites

    International Nuclear Information System (INIS)

    Basha, A.F.; Amin, M.; Abdel Samad, H.A.

    1985-07-01

    Electric conduction measurements were made at different temperatures and fields on thin films NiCl 2 -PVA composites prepared by casting. The conduction is assumed to be generally ionic in nature and polarization contribution is suggested to operate mainly at higher temperatures. Space-charge limited conduction and relaxation phenomena have been observed. The obtained results made it possible to determine a complete set of conduction parameters including carrier mobility, carrier concentration, traps density, Fermi energy, activation energy, etc. (author)

  4. Electrically conductive polymer concrete coatings

    Science.gov (United States)

    Fontana, Jack J.; Elling, David; Reams, Walter

    1990-01-01

    A sprayable electrically conductive polymer concrete coating for vertical d overhead applications is described. The coating is permeable yet has low electrical resistivity (<10 ohm-cm), good bond strength to concrete substrates, and good weatherability. A preferred formulation contains about 60 wt % calcined coke breeze, 40 wt % vinyl ester with 3.5 wt % modified bentonite clay. Such formulations apply evenly and provide enough rigidity for vertical or overhead structures so there is no drip or sag.

  5. Electrical Conductivity in Transition Metals

    Science.gov (United States)

    Talbot, Christopher; Vickneson, Kishanda

    2013-01-01

    The aim of this "Science Note" is to describe how to test the electron-sea model to determine whether it accurately predicts relative electrical conductivity for first-row transition metals. In the electron-sea model, a metal crystal is viewed as a three-dimensional array of metal cations immersed in a sea of delocalised valence…

  6. Relaxation model of radiation-induced conductivity in polymers

    Science.gov (United States)

    Zhutayeva, Yu. R.; Khatipov, S. A.

    1999-05-01

    The paper suggests a relaxation model of radiation-induced conductivity (RIC) in polymers. According to the model, the transfer of charges generated in the polymer volume by ionizing radiation takes place with the participation of molecular relaxation processes. The mechanism of electron transport consists in the transfer of the charge directly between traps when they draw close to one another due to the rotation of macromolecule segments. The numerical solutions of the corresponding kinetic equations for different distribution functions Q( τ) of the times of molecular relaxation and for different functions of the probability P( τ, τ') of charge transfer in the `overlapping' regions of the diffusion spheres of the segments are analyzed. The relaxation model provides an explanation of the non-Arrhenius behavior of the RIC temperature dependence, the power dependence of RIC on the dose rate with a power index in the interval 0.5-1.0, the appearance of maxima in the curves of the RIC temporal dependence and their irreversible character in the region of large dose rates (more than 1 Gy/s). The model can be used for interpreting polymer RIC in conditions of kinetic mobility of macromolecules.

  7. Electrical conductivity in random alloys

    International Nuclear Information System (INIS)

    Mookerjee, A.; Thakur, P.K.; Yussouff, M.

    1984-12-01

    Based on the augmented space formalism introduced by one of us and the use of the Ward identity and the Bethe-Sapeter equation, a formalism has been developed for the calculation of electrical conductivity for random alloys. A simple application is made to a model case, and it is argued that the formalism enables us to carry out viable calculations on more realistic models of alloys. (author)

  8. Electrical conductivity in random alloys

    International Nuclear Information System (INIS)

    Mookerjee, A.; Yussouff, M.

    1983-06-01

    Starting from the augmented space formalism by one of us, and the use of the Ward identity and Bethe Salpeter equation, a complete formalism for the calculation of the electrical conductivity in tight-binding models of random binary alloys has been developed. The formalism is practical in the sense that viable calculations may be carried out with its help for realistics models of alloy systems. (author)

  9. Electrical response of relaxing dielectrics compressed by arbitrary stress pulses

    International Nuclear Information System (INIS)

    Lysne, P.C.

    1983-01-01

    The theoretical problem of the electric response of biased dielectrics and piezoelectrics subjected to planar stress pulse loading is considered. The materials are taken to exhibit dielectric relaxation in the sense that changes in the polarization induced by electric fields do not occur instantaneously with changes in the fields. While this paper considers arbitrary stress pulse loading of the specimen, examples that are amenable to projectile impact techniques are considered in detail. They are shock reverberation, thin pulse, and ramp loading experiments. It is anticipated that these experiments will play a role in investigations of dielectric relaxation caused by shock induced damage in insulators

  10. Proton conductivity and relaxation properties of chitosan-acetate films

    International Nuclear Information System (INIS)

    Prokhorov, E.; Luna-Bárcenas, G.; González-Campos, J.B.; Kovalenko, Yu.; García-Carvajal, Z.Y.; Mota-Morales, J.

    2016-01-01

    Graphical abstract: Temperature dependence of conductivity, the number of density and proton mobility in chitosan-acetate film. - Highlights: • DD, conductivity, Vogel temperature dependent on the concentration of acetic acid. • Proton conductivity of CS-acetate films interpreted using two Grotthuss mechanisms. • Transformation between two mechanisms observed at the glass transition temperature. - Abstract: The effect of aqueous acetic acid solution concentration during the preparation of chitosan-acetate (CS-acetate) films on the conductivity and relaxation properties were studied by dielectric and FTIR spectroscopies, TGA measurements and X-Ray diffraction. Analyses of the experimental results on the degree of deacetylation, water absorption, conductivity, Vogel temperature and activation energy demonstrate a strong dependence of these parameters on the concentration of the acid acetic solutions from which the films have been obtained. The proton conductivity and relaxation properties of CS-acetate films have been interpreted using two Grotthuss “structural diffusion” and “pack-acid” mechanisms. The transformation between these two mechanisms observed at temperature higher than CS-acetate glass transition temperature is due to an increase in the thermal motion of CS chains, water evaporation, hydrogen bond between water molecules and side groups of CS breaking and formation of new bonds between NH 3 + and acetate ions. Additionally, application of the Rice and Roth model allowed estimating the temperature dependence of proton number and their mobility in CS-acetate films. A systematic interpretation on the appropriate conductivity mechanism will help trigger the design of smart materials used in flexible electronic, solid polymer electrolytes for fuel cells and solid polymer batteries based on CS-acetate films.

  11. Electric Conductivity of Phosphorus Nanowires

    International Nuclear Information System (INIS)

    Jing-Xiang, Zhang; Hui, Li; Xue-Qing, Zhang; Kim-Meow, Liew

    2009-01-01

    We present the structures and electrical transport properties of nanowires made from different strands of phosphorus chains encapsulated in carbon nanotubes. Optimized by density function theory, our results indicate that the conductance spectra reveal an oscillation dependence on the size of wires. It can be seen from the density of states and current-voltage curves that the structure of nanowires affects their properties greatly. Among them, the DNA-like double-helical phosphorus nanowire exhibits the distinct characteristic of an approximately linear I – V relationship and has a higher conductance than others. The transport properties of phosphorus nanowires are highly correlated with their microstructures. (condensed matter: structure, mechanical and thermal properties)

  12. Dielectric relaxation and ac conductivity behaviour of polyvinyl alcohol–HgSe quantum dot hybrid films

    International Nuclear Information System (INIS)

    Sinha, Subhojyoti; Chatterjee, Sanat Kumar; Meikap, Ajit Kumar; Ghosh, Jiten

    2014-01-01

    Here we report a comparative study on the dielectric relaxation and ac conductivity behaviour of pure polyvinyl alcohol (PVA) and PVA–mercury selenide (HgSe) quantum dot hybrid films in the temperature range 298 K ⩽ T ⩽ 420 K and in the frequency range 100 Hz ⩽ f ⩽ 1 MHz. The prepared nanocomposite exhibits a larger dielectric constant as compared to the pure PVA. The real and imaginary parts of the dielectric constants were found to fit appreciably with the modified Cole–Cole equation, from which temperature-dependent values of the relaxation times, free charge carrier conductivity and space charge carrier conductivity were calculated. The relaxation time decreases with the quantum dot's inclusion in the PVA matrix and with an increase in temperature, whereas free charge carrier conductivity and space charge carrier conductivity increases with an increase in temperature. An increase in ac conductivity for the nanocomposites has also been observed, while the charge transport mechanism was found to follow the correlated barrier hopping model in both cases. An easy-path model with a suitable electrical equivalent circuit has been employed to analyse the temperature-dependent impedance spectra. The imaginary part of the complex electric modulus spectra exhibit an asymmetric nature and a non-Debye type of behaviour, which has been elucidated considering a generalized susceptibility function. The electric modulus spectra of the nanocomposite demonstrate a smaller amplitude and broader width, as compared to the pure PVA sample. (paper)

  13. Dynamical electrical conductivity of graphene.

    Science.gov (United States)

    Rani, Luxmi; Singh, Navinder

    2017-06-28

    For graphene (a Dirac material) it has been theoretically predicted and experimentally observed that DC resistivity is proportional to T 4 when the temperature is much less than Bloch-Grüneisen temperature ([Formula: see text]) and T-linear in the opposite case ([Formula: see text]). Going beyond this case, we investigate the dynamical electrical conductivity in graphene using the powerful method of the memory function formalism. In the zero frequency regime, we obtain the above mentioned behavior which was previously obtained using the Bloch-Boltzmann kinetic equation. In the finite frequency regime, we obtain several new results: (1) the generalized Drude scattering rate, in the zero temperature limit, shows [Formula: see text] behavior at low frequencies ([Formula: see text]) and saturates at higher frequencies. We also observed the Holstein mechanism, however, with different power laws from that in the case of metals; (2) at higher frequencies, [Formula: see text], and higher temperatures [Formula: see text], we observed that the generalized Drude scattering rate is linear in temperature. In addition, several other results are also obtained. With the experimental advancement of this field, these results should be experimentally tested.

  14. Dynamical electrical conductivity of graphene

    Science.gov (United States)

    Rani, Luxmi; Singh, Navinder

    2017-06-01

    For graphene (a Dirac material) it has been theoretically predicted and experimentally observed that DC resistivity is proportional to T 4 when the temperature is much less than Bloch-Grüneisen temperature ({{ \\Theta }\\text{BG}} ) and T-linear in the opposite case (T\\gg {{ \\Theta }\\text{BG}} ). Going beyond this case, we investigate the dynamical electrical conductivity in graphene using the powerful method of the memory function formalism. In the zero frequency regime, we obtain the above mentioned behavior which was previously obtained using the Bloch-Boltzmann kinetic equation. In the finite frequency regime, we obtain several new results: (1) the generalized Drude scattering rate, in the zero temperature limit, shows {ω4} behavior at low frequencies (ω \\ll {{k}\\text{B}}{{ \\Theta }\\text{BG}}/\\hbar ) and saturates at higher frequencies. We also observed the Holstein mechanism, however, with different power laws from that in the case of metals; (2) at higher frequencies, ω \\gg {{k}\\text{B}}{{ \\Theta }\\text{BG}}/\\hbar , and higher temperatures T\\gg {{ \\Theta }\\text{BG}} , we observed that the generalized Drude scattering rate is linear in temperature. In addition, several other results are also obtained. With the experimental advancement of this field, these results should be experimentally tested.

  15. Study of dielectric relaxation and AC conductivity of InP:S single crystal

    Science.gov (United States)

    El-Nahass, M. M.; Ali, H. A. M.; El-Shazly, E. A.

    2012-07-01

    The dielectric relaxation and AC conductivity of InP:S single crystal were studied in the frequency range from 100 to 5.25 × 105 Hz and in the temperature range from 296 to 455 K. The dependence of the dielectric constant (ɛ1) and the dielectric loss (ɛ2) on both frequency and temperature was investigated. Since no peak was observed on the dielectric loss, we used a method based on the electric modulus to evaluate the activation energy of the dielectric relaxation. Scaling of the electric modulus spectra showed that the charge transport dynamics is independent of temperature. The AC conductivity (σAC) was found to obey the power law: Aωs. Analysis of the AC conductivity data and the frequency exponent showed that the correlated barrier hopping (CBH) model is the dominant mechanism for the AC conduction. The variation of AC conductivity with temperature at different frequencies showed that σAC is a thermally activated process.

  16. Conductivity relaxation and charge transport of trihexyl tetradecyl phosphonium dicyanamide ionic liquid by broadband dielectric spectroscopy

    Science.gov (United States)

    Thasneema K., K.; Thayyil, M. Shahin; Krishna Kumar N., S.; Govindaraj, G.; Saheer, V. C.

    2018-04-01

    Usually ionic liquids consists of a large organic cation with low symmetry such as imidazolium, pyridinium, quaternary ammonium or phosponium etc combined with enormously wide range of inorganic or organic symmetric anion with melting point below 100. Ionic liquids existing in an extremely large number of possible ion pair combinations. It offers a very wide range of thermo physical properties led to the concept of designer solvents for specific applications. Due to the features of high chemical and thermal stability, low vapor pressure non flammability high ionic conductivity, and they show a good solvent ability towards a great variety of organic or inorganic compounds, ionic liquids have a widespread use in many areas such as batteries, fuel cell, solar cells, super capacitors etc. The main focus of this work is the study of molecular dynamics and conductivity relaxation of amorphous Trihexyl tetradecyl phosphonium dicyanamide ([P14,6,6,6][N(CN)2]) ionic liquid which is proved as a better electrolyte in super capacitors, over a wide frequency 10-2 Hz to 107 Hz and the temperature range between 123k and 265 k by means of Broadband Dielectric Spectroscopy. We observe alpha conductivity relaxation and secondary relaxation above and below Glass Transition Temperature. The experimental results were analyzed using electric modulus representation. The analysis emphasis the inter molecular interaction and the nature of glass forming system, whether it is fragile or strong system. The ionic liquid shows a fragile behavior and the fragility index m=123.59. TGA result of the sample exhibit a good resistance to thermal decomposition, up to 300°C.

  17. Complex electric conductivity of rocks

    International Nuclear Information System (INIS)

    Rocha, B.R.P. da.

    1982-01-01

    Laboratory measurements of complex conductivity were made on 28 drill-core samples from area MM1-Prospect 1 of the Carajas Mining District. The objective of this research was to help interpret field geophysical survey of the area using Induced Polarization and AFMAG methods. A petrographic study of the samples was done, using thin sections, polished sections and X-ray diffraction. Copper content, in the form of sulfides, was determined using atomic absorption. As a result of the petrographic study, the samples were classified in five distinct groups: granite, biotite schist, amphibolite and magnetite quartzite-iron formation. The grade of Cu was variable in the five groups, ranging from 50 ppm to 6000 ppm. In conclusion, these measurements show that the field Induced Polarization and AFMAG anomalies near these three drill holes (F1, F2 and F3) are due primarily to the magnetic iron formation, and secondarily due to associated low-grade chalcopyrite mineralization. (author) [pt

  18. Electrical conductivity study on polythiophenes films

    International Nuclear Information System (INIS)

    Youm, I.; Cadene, M.

    1994-10-01

    The electrical conduction mechanism of two classes of polythiophenes: polythiophene (PT) and poly(3-methylthiophene) (PMT) films containing various levels of doping counter-ions was investigated. The temperature dependence of electrical conductivity obeys the Mott equation based on variable range hopping. The dimension of the variable range hopping is correlated with the structure of the conducting polymer. It seems for these polymers that carrier transport via mobile conjugational defects does not play a detectable role. (author). 17 refs, 3 figs, 1 tab

  19. Calibration-free electrical conductivity measurements for highly conductive slags

    International Nuclear Information System (INIS)

    Macdonald, Christopher J.; Gao, Huang; Pal, Uday B.; Van den Avyle, James A.; Melgaard, David K.

    2000-01-01

    This research involves the measurement of the electrical conductivity (K) for the ESR (electroslag remelting) slag (60 wt.% CaF 2 - 20 wt.% CaO - 20 wt.% Al 2 O 3 ) used in the decontamination of radioactive stainless steel. The electrical conductivity is measured with an improved high-accuracy-height-differential technique that requires no calibration. This method consists of making continuous AC impedance measurements over several successive depth increments of the coaxial cylindrical electrodes in the ESR slag. The electrical conductivity is then calculated from the slope of the plot of inverse impedance versus the depth of the electrodes in the slag. The improvements on the existing technique include an increased electrochemical cell geometry and the capability of measuring high precision depth increments and the associated impedances. These improvements allow this technique to be used for measuring the electrical conductivity of highly conductive slags such as the ESR slag. The volatilization rate and the volatile species of the ESR slag measured through thermogravimetric (TG) and mass spectroscopy analysis, respectively, reveal that the ESR slag composition essentially remains the same throughout the electrical conductivity experiments

  20. Quasiparticle relaxation in Heavy Fermions studied using Inverse Fourier Transform of optical conductivity

    International Nuclear Information System (INIS)

    Dordevic, S.V.

    2012-01-01

    Inverse Fourier Transform of optical conductivity is used for studies of quasiparticle relaxation in Heavy Fermions in time domain. We demonstrate the usefulness of the procedure on model spectra and then use it to study quasiparticle relaxation in two Heavy Fermions YbFe 4 Sb 12 and CeRu 4 Sb 12 . Optical conductivity in time domain reveals details of quasiparticle relaxation close to the Fermi level, not readily accessible from the spectra in the frequency domain. In particular, we find that the relaxation of heavy quasiparticles does not start instantaneously, but typically after a few hundred femto-seconds.

  1. Electrical and thermal conductivities in dense plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Faussurier, G., E-mail: gerald.faussurier@cea.fr; Blancard, C.; Combis, P.; Videau, L. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-09-15

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  2. Electrical conductivity of silicon carbide composites

    International Nuclear Information System (INIS)

    Scholz, R.; Greeff, J. de; Vinche, C.; Frias Rebelo, A.

    1997-01-01

    The electrical conductivity was measured on two SiC/SiC composite materials in the temperature range from room temperature up to 1000degC in order to estimate the magnitude of MHD effects in liquid metal blankets if SiC/SiC composites are used as structural materials. For both types of material, the electrical conductivity increased continuously with temperature. The conductivity values ranged from 350 (Ωm) -1 at room temperature to 550 (Ωm) -1 at 1000degC, indicating that the materials tested cannot be treated as an electrical insulator in a MHD analysis for liquid metal blanket studies. (author)

  3. Electric field dependence of the spin relaxation anisotropy in (111) GaAs/AlGaAs quantum wells

    International Nuclear Information System (INIS)

    Balocchi, A; Amand, T; Renucci, P; Duong, Q H; Marie, X; Wang, G; Liu, B L

    2013-01-01

    Time-resolved optical spectroscopy experiments in (111)-oriented GaAs/AlGaAs quantum wells (QWs) show a strong electric field dependence of the conduction electron spin relaxation anisotropy. This results from the interplay between the Dresselhaus and Rashba spin splitting in this system with C 3v symmetry. By varying the electric field applied perpendicular to the QW plane from 20 to 50 kV cm −1 the anisotropy of the spin relaxation time parallel (τ s ∥ ) and perpendicular (τ s ⊥ ) to the growth axis can be first canceled and eventually inversed with respect to the one usually observed in III–V zinc-blende QW (τ s ⊥ = 2τ s ∥ ). This dependence stems from the nonlinear contributions of the k-dependent conduction band spin splitting terms which begin to play the dominant spin relaxing role while the linear Dresselhaus terms are compensated by the Rashba ones through the applied bias. A spin density matrix model for the conduction band spin splitting including both linear and cubic terms of the Dresselhaus Hamiltonian is used which allows a quantitative description of the measured electric field dependence of the spin relaxation anisotropy. The existence of an isotropic point where the spin relaxation tensor reduces to a scalar is predicted and confirmed experimentally. The spin splitting compensation electric field and collision processes type in the QW can be likewise directly extracted from the model without complementary measurements. (paper)

  4. Rapidly curable electrically conductive clear coatings

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, Mark P.; Anderson, Lawrence G.; Post, Gordon L.

    2018-01-16

    Rapidly curable electrically conductive clear coatings are applied to substrates. The electrically conductive clear coating includes to clear layer having a resinous binder with ultrafine non-stoichiometric tungsten oxide particles dispersed therein. The clear coating may be rapidly cured by subjecting the coating to infrared radiation that heats the tungsten oxide particles and surrounding resinous binder. Localized heating increases the temperature of the coating to thereby thermally cure the coating, while avoiding unwanted heating of the underlying substrate.

  5. Ac conductivity and relaxation mechanism in Ba0.9Sr0.1TiO3

    International Nuclear Information System (INIS)

    Singh, A.K.; Barik, Subrat K.; Choudhary, R.N.P.; Mahapatra, P.K.

    2009-01-01

    The ac conductivity and relaxation mechanism in Ba 0.9 Sr 0.1 TiO 3 ceramics have been investigated systematically. A high-temperature solid-state reaction technique was used to synthesize the compound. The formation of the compound was checked by an X-ray diffraction (XRD) technique. The dielectric permittivity and the loss tangent of the sample were measured in a frequency range from 1 kHz to 1 MHz at different temperatures (30-500 deg. C). A study on dielectric properties reveals the electrical relaxation phenomenon occurs in the material. The activation energy was calculated from the temperature variation of dc conductivity. Studies of frequency and temperature dependence of ac conductivity of the compound suggest that conduction process in the material is thermally activated.

  6. The electrical conductivity and longitudinal magnetoresistance of metallic nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Moraga, Luis, E-mail: luismoragajaramillo@gmail.com [Universidad Central de Chile, Toesca 1783, Santiago 8370178 (Chile); Henriquez, Ricardo, E-mail: rahc.78@gmail.com [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Bravo, Sergio, E-mail: bravo.castillo.sergio@gmail.com [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Solis, Basilio, E-mail: bsolis1984@gmail.com [Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn (Germany)

    2017-03-01

    Proceeding from exact solutions of the Boltzmann transport equation in the relaxation time approximation, we present formulas for the electrical conductivity and longitudinal magnetoresistance of single-crystalline cylindrical nanotubes. The effects of surface scattering are taken into account by introducing different specularity parameters at the inner and outer surfaces. For small values of the inner diameter, these formulas reduce to the respective expressions for cylindrical nanowires. It is found that the existing measurements of the resistivity of nanotubes (Venkata Kamalakar and Raychaudhuri, New J. Phys. 14, 043032 (2012)) can be accurately described by this formalism.

  7. The electrical conductivity of an interacting electron gas

    International Nuclear Information System (INIS)

    Kojima, D.Y.

    1977-01-01

    A manybody theory by the propagator method developed by Montroll and Ward for the equilibrium statistical mechanics, is reformulated to describe the electrical conductivity for an electron gas system containing impurity. The theory includes electron-impurity interaction to the infinite order and electron-electron interaction to the first order exchange effect. The propagator used by Montroll and Ward is separated into two propagators, each of which satisfies either Bloch or Schroedinger equation, to utilize the perturbation method. Correct counting of graphs are presented. Change in the relaxation time due to the electron-electron interaction is explicity shown and compared with recent works [pt

  8. Temperature dependent dielectric relaxation and ac-conductivity of alkali niobate ceramics studied by impedance spectroscopy

    Science.gov (United States)

    Yadav, Abhinav; Mantry, Snigdha Paramita; Fahad, Mohd.; Sarun, P. M.

    2018-05-01

    Sodium niobate (NaNbO3) ceramics is prepared by conventional solid state reaction method at sintering temperature 1150 °C for 4 h. The structural information of the material has been investigated by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FE-SEM). The XRD analysis of NaNbO3 ceramics shows an orthorhombic structure. The FE-SEM micrograph of NaNbO3 ceramics exhibit grains with grain sizes ranging between 1 μm to 5 μm. The surface coverage and average grain size of NaNbO3 ceramics are found to be 97.6 % and 2.5 μm, respectively. Frequency dependent electrical properties of NaNbO3 is investigated from room temperature to 500 °C in wide frequency range (100 Hz-5 MHz). Dielectric constant, ac-conductivity, impedance, modulus and Nyquist analysis are performed. The observed dielectric constant (1 kHz) at transition temperature (400 °C) are 975. From conductivity analysis, the estimated activation energy of NaNbO3 ceramics is 0.58 eV at 10 kHz. The result of Nyquist plot shows that the electrical behavior of NaNbO3 ceramics is contributed by grain and grain boundary responses. The impedance and modulus spectrum asserts that the negative temperature coefficient of resistance (NTCR) behavior and non-Debye type relaxation in NaNbO3.

  9. ac Conductivity analysis and dielectric relaxation behaviour of NaNO3-Al2O3 composites

    International Nuclear Information System (INIS)

    Anantha, P.S.; Hariharan, K.

    2005-01-01

    The electrical conductivity of NaNO 3 -xAl 2 O 3 composites has been studied over the wide range of temperature and frequency by means of impedance spectroscopy. The real part of the frequency dependent conductivity exhibits a simple power law feature and the dimensionless frequency exponent n has been determined. The conductivity spectra show scaling behaviour when the conductivity spectra are scaled by σ dc T, where T is temperature in Kelvin. The real part of dielectric permittivity shows saturation at higher frequencies and a strong dispersion at lower frequencies. The imaginary part of permittivity varies inversely with frequency, due to the presence of dc conductivity. The frequency dependent plots of M' and Z' show that the conductivity relaxation is non-Debye in nature. The Kohlrausch-Williams-Watts stretched exponential function was used to describe the modulus spectra and the stretching exponent β is found to be temperature independent. The conductivity relaxation time has been estimated from the modulus spectra. The activation energy responsible for relaxation has been evaluated and it was found to be almost same as that of dc conductivity

  10. A New Vogel-Like Law: Ionic Conductivity, Dielectric Relaxation and Viscosity Near the Glass Transition

    National Research Council Canada - National Science Library

    Bendler, John

    2001-01-01

    A model, based on defect diffusion, is developed that describes temperature and pressure dependence of dielectric relaxation, ionic conductivity and viscosity of glass-forming liquids near the glass...

  11. Mechanisms of electrical conductivity in olivine

    International Nuclear Information System (INIS)

    Schock, R.N.; Duba, A.G.; Shankland, T.J.

    1984-01-01

    Data on the electrical conductivity and the thermoelectric effect in single crystals indicate that the charge conduction mechanism in pure magnesium forsterite is electrons. The concentration of electrons can be varied by controlling the number of oxygen vacancies through manipulation of the oxygen pressure. For iron bearing olivine, the conduction mechanism is by electron holes localized on an iron ion. Since iron strongly affects the creep process as well, oxidation of iron is probably accompanied by the production of magnesium vacancies. 15 references

  12. Making Complex Electrically Conductive Patterns on Cloth

    Science.gov (United States)

    Chu, Andrew; Fink, Patrick W.; Dobbins, Justin A.; Lin, Greg Y.; Scully, Robert C.; Trevino, Robert

    2008-01-01

    A method for automated fabrication of flexible, electrically conductive patterns on cloth substrates has been demonstrated. Products developed using this method, or related prior methods, are instances of a technology known as 'e-textiles,' in which electrically conductive patterns ar formed in, and on, textiles. For many applications, including high-speed digital circuits, antennas, and radio frequency (RF) circuits, an e-textile method should be capable of providing high surface conductivity, tight tolerances for control of characteristic impedances, and geometrically complex conductive patterns. Unlike prior methods, the present method satisfies all three of these criteria. Typical patterns can include such circuit structures as RF transmission lines, antennas, filters, and other conductive patterns equivalent to those of conventional printed circuits. The present method overcomes the limitations of the prior methods for forming the equivalent of printed circuits on cloth. A typical fabrication process according to the present method involves selecting the appropriate conductive and non-conductive fabric layers to build the e-textile circuit. The present method uses commercially available woven conductive cloth with established surface conductivity specifications. Dielectric constant, loss tangent, and thickness are some of the parameters to be considered for the non-conductive fabric layers. The circuit design of the conductive woven fabric is secured onto a non-conductive fabric layer using sewing, embroidery, and/or adhesive means. The portion of the conductive fabric that is not part of the circuit is next cut from the desired circuit using an automated machine such as a printed-circuit-board milling machine or a laser cutting machine. Fiducials can be used to align the circuit and the cutting machine. Multilayer circuits can be built starting with the inner layer and using conductive thread to make electrical connections between layers.

  13. 3D electrical conductivity tomography of volcanoes

    Science.gov (United States)

    Soueid Ahmed, A.; Revil, A.; Byrdina, S.; Coperey, A.; Gailler, L.; Grobbe, N.; Viveiros, F.; Silva, C.; Jougnot, D.; Ghorbani, A.; Hogg, C.; Kiyan, D.; Rath, V.; Heap, M. J.; Grandis, H.; Humaida, H.

    2018-05-01

    Electrical conductivity tomography is a well-established galvanometric method for imaging the subsurface electrical conductivity distribution. We characterize the conductivity distribution of a set of volcanic structures that are different in terms of activity and morphology. For that purpose, we developed a large-scale inversion code named ECT-3D aimed at handling complex topographical effects like those encountered in volcanic areas. In addition, ECT-3D offers the possibility of using as input data the two components of the electrical field recorded at independent stations. Without prior information, a Gauss-Newton method with roughness constraints is used to solve the inverse problem. The roughening operator used to impose constraints is computed on unstructured tetrahedral elements to map complex geometries. We first benchmark ECT-3D on two synthetic tests. A first test using the topography of Mt. St Helens volcano (Washington, USA) demonstrates that we can successfully reconstruct the electrical conductivity field of an edifice marked by a strong topography and strong variations in the resistivity distribution. A second case study is used to demonstrate the versatility of the code in using the two components of the electrical field recorded on independent stations along the ground surface. Then, we apply our code to real data sets recorded at (i) a thermally active area of Yellowstone caldera (Wyoming, USA), (ii) a monogenetic dome on Furnas volcano (the Azores, Portugal), and (iii) the upper portion of the caldera of Kīlauea (Hawai'i, USA). The tomographies reveal some of the major structures of these volcanoes as well as identifying alteration associated with high surface conductivities. We also review the petrophysics underlying the interpretation of the electrical conductivity of fresh and altered volcanic rocks and molten rocks to show that electrical conductivity tomography cannot be used as a stand-alone technique due to the non-uniqueness in

  14. Thermophysical Properties of Liquid Te: Density, Electrical Conductivity, and Viscosity

    Science.gov (United States)

    Li, C.; Su, C.; Lehoczky, S. L.; Scripa, R. N.; Ban, H.; Lin, B.

    2004-01-01

    The thermophysical properties of liquid Te, namely, density, electrical conductivity, and viscosity, were determined using the pycnometric and transient torque methods from the melting point of Te (723 K) to approximately 1150 K. A maximum was observed in the density of liquid Te as the temperature was increased. The electrical conductivity of liquid Te increased to a constant value of 2.89 x 10(exp 5 OMEGA-1m-1) as the temperature was raised above 1000 K. The viscosity decreased rapidly upon heating the liquid to elevated temperatures. The anomalous behaviors of the measured properties are explained as caused by the structural transitions in the liquid and discussed in terms of Eyring's and Bachiskii's predicted behaviors for homogeneous liquids. The Properties were also measured as a function of time after the liquid was coded from approximately 1173 or 1123 to 823 K. No relaxation phenomena were observed in the properties after the temperature of liquid Te was decreased to 823 K, in contrast to the relaxation behavior observed for some of the Te compounds.

  15. Stay connected: Electrical conductivity of microbial aggregates.

    Science.gov (United States)

    Li, Cheng; Lesnik, Keaton Larson; Liu, Hong

    2017-11-01

    The discovery of direct extracellular electron transfer offers an alternative to the traditional understanding of diffusional electron exchange via small molecules. The establishment of electronic connections between electron donors and acceptors in microbial communities is critical to electron transfer via electrical currents. These connections are facilitated through conductivity associated with various microbial aggregates. However, examination of conductivity in microbial samples is still in its relative infancy and conceptual models in terms of conductive mechanisms are still being developed and debated. The present review summarizes the fundamental understanding of electrical conductivity in microbial aggregates (e.g. biofilms, granules, consortia, and multicellular filaments) highlighting recent findings and key discoveries. A greater understanding of electrical conductivity in microbial aggregates could facilitate the survey for additional microbial communities that rely on direct extracellular electron transfer for survival, inform rational design towards the aggregates-based production of bioenergy/bioproducts, and inspire the construction of new synthetic conductive polymers. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Thermodynamic parameters of elasticity and electrical conductivity ...

    African Journals Online (AJOL)

    The thermodynamic parameters (change in free energy of elasticity, DGe; change in enthalpy of elasticity, DHe; and change in entropy of elasticity, DSe) and the electrical conductivity of natural rubber composites reinforced separately with some agricultural wastes have been determined. Results show that the reinforced ...

  17. Shear-induced changes of electrical conductivity in suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Crawshaw, John; Meeten, Gerald [Schlumberger Cambridge Research, Cambridge (United Kingdom)

    2006-12-15

    The effect of shear on electrical conductivity (rheo-conduction) is studied to give information about particle behaviour in suspensions. Past work is reviewed, and expressions are derived for the rheo-conduction of a suspension of nonconducting spheroids in a conducting matrix for current flow, parallel and normal to the suspension flow direction. A simple apparatus to study rheo-conduction in pipe flow is described, and measurements of steady and time-dependent effects are reported for various suspensions of colloidal particles. Suspensions of anisometric rod- and platelike particles at low concentrations showed rheo-conductive changes of sign, magnitude and relaxation that were consistent with the particle shape, concentration and interactions. The rheo-conductive response decreased with increasing volume fraction for platelike kaolinite particles, attributed to orientational jamming. Spherical latex particles gave unexpected rheo-conductive changes consistent with shear disruption of a conductive network of particles. It is concluded that rheo-conduction measurements are a useful adjunct to conventional rheometry. (orig.)

  18. Relaxation effects in oxygen-conducting oxides on base of lanthanum gallate (La, Sr)(Ga, Me)O3, Me = Mg, Fe

    International Nuclear Information System (INIS)

    Glavatskikh, T.Yu.; Venskovskij, N.U.; Kaleva, G.M.; Mosunov, A.V.; Politova, E.D.; Stefanovich, S.Yu.

    2003-01-01

    The dielectric and electric conducting properties of the heterosubstituted perovskite-like solid solutions (La, Sr)(Ga, Me)O 3 , Me Mg, Fe are studied. The increase in the ceramics electric conductivity, conditioned by increase in the ion constituent at strengthening the nonstoichiometry by oxygen and electron constituent by the additional introduction of iron is observed by replacing the part of the lanthanum and gallium cations by strontium, magnesium and iron in the solid solutions on the basis of the lanthanum gallate. The ceramics relaxation behavior is identified; the applicability of the model of the vacational electron transfer for the dipole relaxation is established [ru

  19. Electrical and Electrochemical Properties of Conducting Polymers

    Directory of Open Access Journals (Sweden)

    Thanh-Hai Le

    2017-04-01

    Full Text Available Conducting polymers (CPs have received much attention in both fundamental and practical studies because they have electrical and electrochemical properties similar to those of both traditional semiconductors and metals. CPs possess excellent characteristics such as mild synthesis and processing conditions, chemical and structural diversity, tunable conductivity, and structural flexibility. Advances in nanotechnology have allowed the fabrication of versatile CP nanomaterials with improved performance for various applications including electronics, optoelectronics, sensors, and energy devices. The aim of this review is to explore the conductivity mechanisms and electrical and electrochemical properties of CPs and to discuss the factors that significantly affect these properties. The size and morphology of the materials are also discussed as key parameters that affect their major properties. Finally, the latest trends in research on electrochemical capacitors and sensors are introduced through an in-depth discussion of the most remarkable studies reported since 2003.

  20. Electrical conduction of a XLPE nanocomposite

    Science.gov (United States)

    Park, Yong-Jun; Sim, Jae-Yong; Lim, Kee-Joe; Nam, Jin-Ho; Park, Wan-Gi

    2014-07-01

    The resistivity, breakdown strength, and formation of space charges are very important factors for insulation design of HVDC cable. It is known that a nano-sized metal-oxide inorganic filler reduces the formation of space charges in the polymer nanocomposite. Electrical conduction of cross-linked polyethylene(XLPE) nanocomposite insulating material is investigated in this paper. The conduction currents of two kinds of XLPE nanocomposites and XLPE without nano-filler were measured at temperature of 303 ~ 363 K under the applied electric fields of 10 ~ 50 kV/mm. The current of the nanocomposite specimen is smaller than that of XLPE specimen without nano-filler. The conduction mechanism may be explained in terms of Schottky emission and multi-core model.

  1. Electrical conductivity in polyacrylonitrile and perbunan

    International Nuclear Information System (INIS)

    Migahed, M.D.; Bakr, N.A.; Tawansi, A.

    1981-07-01

    The electrical conduction in Ag-PAN-Ag and Ag-NBR-Ag sandwich samples is studied measuring the dependence of current on the applied voltage and temperature. The conduction mechanism depends on the polymer type. A bulk polarization contribution is suggested in the conduction mechanism at high temperatures besides the Schottky emission in the case of PAN and simple carrier jump model in the case of NBR at room temperature. NBR(28) is proved to be more semiconducting than both NBR(38) and PAN. This is attributed to the lowering of the nitrile group content in NBR(28). (author)

  2. Electrical conductivity tensor of an irradiated metal

    International Nuclear Information System (INIS)

    Corciovei, A.; Dumitru, R.D.

    1979-01-01

    A method to calculate the electrical conductivity tensor of an irradiated metal is presented. The proposed method relies on the use of the Kubo formula, evaluated by a perturbation method. The one electron Hamiltonian is written as a sum of two terms: the Hamiltonian of the conduction electrons moving in a periodic lattice and the perturbation, namely, the scattering potential due to the irradiation defects of the ideal crystal. Then, the lowest order of the conductivity is determined by the lowest order of the Laplace transform of the current. An integral equation is written for this last quantity. (author)

  3. Fluctuation-enhanced electric conductivity in electrolyte solutions.

    Science.gov (United States)

    Péraud, Jean-Philippe; Nonaka, Andrew J; Bell, John B; Donev, Aleksandar; Garcia, Alejandro L

    2017-10-10

    We analyze the effects of an externally applied electric field on thermal fluctuations for a binary electrolyte fluid. We show that the fluctuating Poisson-Nernst-Planck (PNP) equations for charged multispecies diffusion coupled with the fluctuating fluid momentum equation result in enhanced charge transport via a mechanism distinct from the well-known enhancement of mass transport that accompanies giant fluctuations. Although the mass and charge transport occurs by advection by thermal velocity fluctuations, it can macroscopically be represented as electrodiffusion with renormalized electric conductivity and a nonzero cation-anion diffusion coefficient. Specifically, we predict a nonzero cation-anion Maxwell-Stefan coefficient proportional to the square root of the salt concentration, a prediction that agrees quantitatively with experimental measurements. The renormalized or effective macroscopic equations are different from the starting PNP equations, which contain no cross-diffusion terms, even for rather dilute binary electrolytes. At the same time, for infinitely dilute solutions the renormalized electric conductivity and renormalized diffusion coefficients are consistent and the classical PNP equations with renormalized coefficients are recovered, demonstrating the self-consistency of the fluctuating hydrodynamics equations. Our calculations show that the fluctuating hydrodynamics approach recovers the electrophoretic and relaxation corrections obtained by Debye-Huckel-Onsager theory, while elucidating the physical origins of these corrections and generalizing straightforwardly to more complex multispecies electrolytes. Finally, we show that strong applied electric fields result in anisotropically enhanced "giant" velocity fluctuations and reduced fluctuations of salt concentration.

  4. Solving hyperbolic heat conduction using electrical simulation

    International Nuclear Information System (INIS)

    Gheitaghy, A. M.; Talaee, M. R.

    2013-01-01

    In the present study, the electrical network simulation method is proposed to solve the hyperbolic and parabolic heat conduction problem considering Cattaneo-Vernoute (C.V) constitutive relation. Using this new proposed numerical model and the electrical circuit simulation program HSPICE, transient temperature and heat flux profiles at slab can be obtained easily and quickly. To verify the proposed method, the obtained numerical results for cases of one dimensional two-layer slab under periodic boundary temperature with perfect and imperfect thermal contact are compared with the published results. Comparisons show the proposed technique might be considered as a useful tool in the analysis of parabolic and hyperbolic thermal problems.

  5. Interface bond relaxation on the thermal conductivity of Si/Ge core-shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Weifeng; He, Yan; Ouyang, Gang, E-mail: gangouy@hunnu.edu.cn [Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education, Synergetic Innovation Center for Quantum Effects and Applications(SICQEA), Hunan Normal University, Changsha 410081 (China); Sun, Changqing [School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2016-01-15

    The thermal conductivity of Si/Ge core-shell nanowires (CSNWs) is investigated on the basis of atomic-bond-relaxation consideration and continuum mechanics. An analytical model is developed to clarify the interface bond relaxation of Si/Ge CSNWs. It is found that the thermal conductivity of Si core can be modulated through covering with Ge epitaxial layers. The change of thermal conductivity in Si/Ge CSNWs should be attributed to the surface relaxation and interface mismatch between inner Si nanowire and outer Ge epitaxial layer. Our results are in well agreement with the experimental measurements and simulations, suggesting that the presented method provides a fundamental insight of the thermal conductivity of CSNWs from the atomistic origin.

  6. Interpreting equilibrium-conductivity and conductivity-relaxation measurements to establish thermodynamic and transport properties for multiple charged defect conducting ceramics.

    Science.gov (United States)

    Zhu, Huayang; Ricote, Sandrine; Coors, W Grover; Kee, Robert J

    2015-01-01

    A model-based interpretation of measured equilibrium conductivity and conductivity relaxation is developed to establish thermodynamic, transport, and kinetics parameters for multiple charged defect conducting (MCDC) ceramic materials. The present study focuses on 10% yttrium-doped barium zirconate (BZY10). In principle, using the Nernst-Einstein relationship, equilibrium conductivity measurements are sufficient to establish thermodynamic and transport properties. However, in practice it is difficult to establish unique sets of properties using equilibrium conductivity alone. Combining equilibrium and conductivity-relaxation measurements serves to significantly improve the quantitative fidelity of the derived material properties. The models are developed using a Nernst-Planck-Poisson (NPP) formulation, which enables the quantitative representation of conductivity relaxations caused by very large changes in oxygen partial pressure.

  7. Electrical conductivity of metal powders under pressure

    Science.gov (United States)

    Montes, J. M.; Cuevas, F. G.; Cintas, J.; Urban, P.

    2011-12-01

    A model for calculating the electrical conductivity of a compressed powder mass consisting of oxide-coated metal particles has been derived. A theoretical tool previously developed by the authors, the so-called `equivalent simple cubic system', was used in the model deduction. This tool is based on relating the actual powder system to an equivalent one consisting of deforming spheres packed in a simple cubic lattice, which is much easier to examine. The proposed model relates the effective electrical conductivity of the powder mass under compression to its level of porosity. Other physically measurable parameters in the model are the conductivities of the metal and oxide constituting the powder particles, their radii, the mean thickness of the oxide layer and the tap porosity of the powder. Two additional parameters controlling the effect of the descaling of the particle oxide layer were empirically introduced. The proposed model was experimentally verified by measurements of the electrical conductivity of aluminium, bronze, iron, nickel and titanium powders under pressure. The consistency between theoretical predictions and experimental results was reasonably good in all cases.

  8. Phonon conductivity and relaxation rate in solids with disturbances by the Green function method

    International Nuclear Information System (INIS)

    Singh, M.

    1980-09-01

    In this present article we have established an expression for the temperature dependence of the lattice thermal conductivity of solids with harmonic disturbances. The relaxation rate for scattering of phonons with point defect is also derived. We will apply the Kubo-correlation function formalism for the thermal conductivity, and the double time temperature dependent Green function technique for the evaluation of correlation functions

  9. New conducted electrical weapons: Electrical safety relative to relevant standards.

    Science.gov (United States)

    Panescu, Dorin; Nerheim, Max; Kroll, Mark W; Brave, Michael A

    2017-07-01

    We have previously published about TASER ® conducted electrical weapons (CEW) compliance with international standards. CEWs deliver electrical pulses that can inhibit a person's neuromuscular control or temporarily incapacitate. An eXperimental Rotating-Field (XRF) waveform CEW and the X2 CEW are new 2-shot electrical weapon models designed to target a precise amount of delivered charge per pulse. They both can deploy 1 or 2 dart pairs, delivered by 2 separate cartridges. Additionally, the XRF controls delivery of incapacitating pulses over 4 field vectors, in a rotating sequence. As in our previous study, we were motivated by the need to understand the cardiac safety profile of these new CEWs. The goal of this paper is to analyze the nominal electrical outputs of TASER XRF and X2 CEWs in reference to provisions of all relevant international standards that specify safety requirements for electrical medical devices and electrical fences. Although these standards do not specifically mention CEWs, they are the closest electrical safety standards and hence give very relevant guidance. The outputs of several TASER XRF and X2 CEWs were measured under normal operating conditions. The measurements were compared against manufacturer specifications. CEWs electrical output parameters were reviewed against relevant safety requirements of UL 69, IEC 60335-2-76 Ed 2.1, IEC 60479-1, IEC 60479-2, AS/NZS 60479.1, AS/NZS 60479.2, IEC 60601-1 and BS EN 60601-1. Our study confirmed that the nominal electrical outputs of TASER XRF and X2 CEWs lie within safety bounds specified by relevant standards.

  10. The electric conductivity of a pion gas

    International Nuclear Information System (INIS)

    Atchison, J.; Rapp, R.

    2017-01-01

    The determination of transport coefficients plays a central role in characterizing hot and dense nuclear matter. In the present work we calculate the electric conductivity of hot hadronic matter by extracting it from the ρ meson spectral function, as its zero-energy limit at vanishing momentum. Using hadronic many-body theory, we calculate the ρ meson self-energy in a pion gas. This requires the dressing of the pion propagators in the ρ self-energy with π - ρ loops, and the inclusion of vertex corrections to maintain gauge invariance. The resulting spectral function is used to calculate the electric conductivity of hot hadronic matter. In particular, we analyze the transport peak of the spectral function and extract its behavior with temperature and coupling strength. Our results suggest that, while obeying lower bounds proposed by conformal field theories in the strong-coupling limit, hot pion matter is a strongly-coupled medium. (paper)

  11. Universality of DC electrical conductivity from holography

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Xian-Hui, E-mail: gexh@shu.edu.cn [Shanghai Key Laboratory of High Temperature Superconductors, Department of Physics, Shanghai University, Shanghai, 200444 (China); Department of Physics, University of California, San Diego, CA92122 (United States); Sin, Sang-Jin, E-mail: sjsin@hangyang.ac.kr [Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Wu, Shao-Feng, E-mail: sfwu@shu.edu.cn [Department of Physics, Shanghai University, Shanghai, 200444 (China)

    2017-04-10

    We propose a universal formula of dc electrical conductivity in rotational- and translational-symmetries breaking systems via the holographic duality. This formula states that the ratio of the determinant of the dc electrical conductivities along any spatial directions to the black hole area density in zero-charge limit has a universal value. As explicit illustrations, we give several examples elucidating the validation of this formula: We construct an anisotropic black brane solution, which yields linear in temperature for the in-plane resistivity and insulating behavior for the out-of-plane resistivity; We also construct a spatially isotropic black brane solution that both the linear-T and quadratic-T contributions to the resistivity can be realized.

  12. Electric conductivity and bootstrap current in tokamak

    International Nuclear Information System (INIS)

    Mao Jianshan; Wang Maoquan

    1996-12-01

    A modified Ohm's law for the electric conductivity calculation is presented, where the modified ohmic current can be compensated by the bootstrap current. A comparison of TEXT tokamak experiment with the theories shows that the modified Ohm's law is a more close approximation to the tokamak experiments than the classical and neoclassical theories and can not lead to the absurd result of Z eff <1, and the extended neoclassical theory would be not necessary. (3 figs.)

  13. Electrically driven magnetic relaxation in multiferroic LuFe2O4

    International Nuclear Information System (INIS)

    Wang Fen; Li Changhui; Zou Tao; Liu Yi; Sun Young

    2010-01-01

    We report the electrical control of magnetization in multiferroic LuFe 2 O 4 by applying short current pulses. The magnitude of the induced magnetization change depends on the pulse width and current density. The voltage variation during the applied current pulses evidences an electric-field-induced breakdown of charge order and excludes the role of Joule heating. This current driven magnetization change can be interpreted with a three-temperature model in which the delocalized electrons accelerate spin relaxation through a strong spin-charge coupling inherent to multiferroicity. The electrically assisted magnetic relaxation provides a new approach for electrical control of magnetization.

  14. The electrical conductivity of sodium polysulfide melts

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Meihui [Univ. of California, Berkeley, CA (United States)

    1992-06-01

    The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na2S4 and Na2S5 were measured as a function of temperature (range: 300 to 360°C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.

  15. The electrical conductivity of sodium polysulfide melts

    Energy Technology Data Exchange (ETDEWEB)

    Meihui Wang.

    1992-06-01

    The sodium polysulfide melt has been described by a macroscopic model. This model considers the melt to be composed of sodium cations, monosulfide anions, and neutral sulfur solvent. The transport equations of concentrated-solution theory are used to derived the governing equations for this binaryelectrolyte melt model. These equations relate measurable transport properties to fundamental transport parameters. The focus of this research is to measure the electrical conductivity of sodium polysulfide melts and calculate one of fundamental transport parameters from the experimental data. The conductance cells used in the conductivity measurements are axisymmetric cylindrical cells with a microelectrode. The electrode effects, including double-layer capacity, charge transfer resistance, and concentration overpotential, were minimized by the use of the alternating current at an adequately high frequency. The high cell constants of the conductance cells not only enhanced the experimental accuracy but also made the electrode effects negligible. The electrical conductivities of sodium polysulfide Na{sub 2}S{sub 4} and Na{sub 2}S{sub 5} were measured as a function of temperature (range: 300 to 360{degree}C). Variations between experiments were only up to 2%. The values of the Arrhenius activation energy derived from the experimental data are about 33 kJ/mol. The fundamental transport parameter which quantifies the interaction within sodium cations and monosulfide anions are of interest and expected to be positive. Values of it were calculated from the experimental conductivity data and most of them are positive. Some negative values were obtained probably due to the experimental errors of transference number, diffusion coefficient, density or conductivity data.

  16. Heat and electrical conductivity of thermotropic liquid crystals

    International Nuclear Information System (INIS)

    Saidov, N.S.; Majidov, H.; Saburov, B.S.; Safarov, M.M.

    1989-01-01

    A results of thermal conduction and electrical conduction of chemo tropic liquid crystals are brought in this article. An installation dependence formula of thermal conduction investigating things from the electrical conduction and temperatures is constructed

  17. Conductivity-Relaxation Relations in Nanocomposite Polymer Electrolytes Containing Ionic Liquid.

    Science.gov (United States)

    Shojaatalhosseini, Mansoureh; Elamin, Khalid; Swenson, Jan

    2017-10-19

    In this study, we have used nanocomposite polymer electrolytes, consisting of poly(ethylene oxide) (PEO), δ-Al 2 O 3 nanoparticles, and lithium bis(trifluoromethanesolfonyl)imide (LiTFSI) salt (with 4 wt % δ-Al 2 O 3 and PEO:Li ratios of 16:1 and 8:1), and added different amounts of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesolfonyl)imide (BMITFSI). The aim was to elucidate whether the ionic liquid is able to dissociate the Li-ions from the ether oxygens and thereby decouple the ionic conductivity from the segmental polymer dynamics. The results from DSC and dielectric spectroscopy show that the ionic liquid speeds up both the segmental polymer dynamics and the motion of the Li + ions. However, a close comparison between the structural (α) relaxation process, given by the segmental polymer dynamics, and the ionic conductivity shows that the motion of the Li + ions decouples from the segmental polymer dynamics at higher concentrations of the ionic liquid (≥20 wt %) and instead becomes more related to the viscosity of the ionic liquid. This decoupling increases with decreasing temperature. In addition to the structural α-relaxation, two more local relaxation processes, denoted β and γ, are observed. The β-relaxation becomes slightly faster at the highest concentration of the ionic liquid (at least for the lower salt concentration), whereas the γ-relaxation is unaffected by the ionic liquid, over the whole concentration range 0-40 wt %.

  18. Potential of mean force for electrical conductivity of dense plasmas

    Science.gov (United States)

    Starrett, C. E.

    2017-12-01

    The electrical conductivity in dense plasmas can be calculated with the relaxation-time approximation provided that the interaction potential between the scattering electron and the ion is known. To date there has been considerable uncertainty as to the best way to define this interaction potential so that it correctly includes the effects of ionic structure, screening by electrons and partial ionization. Current approximations lead to significantly different results with varying levels of agreement when compared to bench-mark calculations and experiments. We present a new way to define this potential, drawing on ideas from classical fluid theory to define a potential of mean force. This new potential results in significantly improved agreement with experiments and bench-mark calculations, and includes all the aforementioned physics self-consistently.

  19. Evaluation of Cow Milk Electrical Conductivity Measurements

    Directory of Open Access Journals (Sweden)

    Constantin Gavan

    2017-11-01

    Full Text Available The efficiency of subclinical mastitis diagnosis using an electrical conductivity (EC meter was evaluated in the dairy farm of Agricultural Research and Development Station ( ARDS Simnic Craiova. The results were compared with those obtained by using the California Mastitis Test (CMT and the Somatic Cell Count (SCC.The milk quarter samples ( 1176 from Holstein Friesian cows were analyzed between September and December 2015. The EC evaluation with  the EC meter  ,showed a high proportion of results differing from SCC and CMT results. The CMT still shows to be the most accessible and efficient test in comparison to the EC meter tested.

  20. Modeling liver electrical conductivity during hypertonic injection.

    Science.gov (United States)

    Castellví, Quim; Sánchez-Velázquez, Patricia; Moll, Xavier; Berjano, Enrique; Andaluz, Anna; Burdío, Fernando; Bijnens, Bart; Ivorra, Antoni

    2018-01-01

    Metastases in the liver frequently grow as scattered tumor nodules that neither can be removed by surgical resection nor focally ablated. Previously, we have proposed a novel technique based on irreversible electroporation that may be able to simultaneously treat all nodules in the liver while sparing healthy tissue. The proposed technique requires increasing the electrical conductivity of healthy liver by injecting a hypersaline solution through the portal vein. Aiming to assess the capability of increasing the global conductivity of the liver by means of hypersaline fluids, here, it is presented a mathematical model that estimates the NaCl distribution within the liver and the resulting conductivity change. The model fuses well-established compartmental pharmacokinetic models of the organ with saline injection models used for resuscitation treatments, and it considers changes in sinusoidal blood viscosity because of the hypertonicity of the solution. Here, it is also described a pilot experimental study in pigs in which different volumes of NaCl 20% (from 100 to 200 mL) were injected through the portal vein at different flow rates (from 53 to 171 mL/minute). The in vivo conductivity results fit those obtained by the model, both quantitatively and qualitatively, being able to predict the maximum conductivity with a 14.6% average relative error. The maximum conductivity value was 0.44 second/m, which corresponds to increasing 4 times the mean basal conductivity (0.11 second/m). The results suggest that the presented model is well suited for predicting on liver conductivity changes during hypertonic saline injection. Copyright © 2017 John Wiley & Sons, Ltd.

  1. Electrical conductivity of sandstone, limestone, and granite

    Energy Technology Data Exchange (ETDEWEB)

    Duba, A.; Piwinskii, A.J.; Santor, M.; Weed, H.C.

    1978-01-01

    The electrical conductivity of cylindrical cores of Westerly granite, Indiana limestone and Nugget, St Peter and Kayenta sandstones was measured at about 25/sup 0/C in vacuo, in air, and after saturation in distilled water, tap water, and 0.1 M NaCl solution. The three-electrode technique with a guard ring and the two-electrode technique without a guard ring were used. Core aspect ratio over the range of 2.00 to 0.25, as well as frequency over the range of 50 Hz to 10 kHz, influences the conductivity of all rocks, especially those measured in vacuo. Measurements from water-saturated samples using a guard ring are not appreciably different from those obtained without a guard ring. The conductivity of rocks saturated in 0.1 M NaCl solution changes least with a change in aspect ratio; for these rocks a linear relationship, known as Archie's Law, exists between log porosity and log conductivity. No simple correlation was found between those factors in rocks saturated with tap or distilled water. Thus, it appears Archie's Law is of questionable value for correlating laboratory data from rocks saturated with low-conductivity fluids.

  2. Electrical detection of spin current and spin relaxation in nonmagnetic semiconductors

    International Nuclear Information System (INIS)

    Miah, M Idrish

    2008-01-01

    We report an electrical method for the detection of spin current and spin relaxation in nonmagnetic semiconductors. Optically polarized spins are dragged by an electric field in GaAs. We use the anomalous Hall effect for the detection of spin current and spin relaxation. It is found that the effect depends on the electric field and doping density as well as on temperature, but not on the excitation power. A calculation for the effect is performed using the measured spin polarization by a pump-probe experiment. The results are also discussed in comparison with a quantitative evaluation of the spin lifetimes of the photogenerated electrons under drift in GaAs

  3. Electrical detection of spin current and spin relaxation in nonmagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M Idrish [Nanoscale Science and Technology Centre and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)], E-mail: m.miah@griffith.edu.au

    2008-09-21

    We report an electrical method for the detection of spin current and spin relaxation in nonmagnetic semiconductors. Optically polarized spins are dragged by an electric field in GaAs. We use the anomalous Hall effect for the detection of spin current and spin relaxation. It is found that the effect depends on the electric field and doping density as well as on temperature, but not on the excitation power. A calculation for the effect is performed using the measured spin polarization by a pump-probe experiment. The results are also discussed in comparison with a quantitative evaluation of the spin lifetimes of the photogenerated electrons under drift in GaAs.

  4. Dielectric relaxations and conduction mechanisms in polyether-clay composite polymer electrolytes under high carbon dioxide pressure.

    Science.gov (United States)

    Kitajima, Shunsuke; Bertasi, Federico; Vezzù, Keti; Negro, Enrico; Tominaga, Yoichi; Di Noto, Vito

    2013-10-21

    The composite material P(EO/EM)-Sa consisting of synthetic saponite (Sa) dispersed in poly[ethylene oxide-co-2-(2-methoxyethoxy)ethyl glycidyl ether] (P(EO/EM)) is studied by "in situ" measurements using broadband electrical spectroscopy (BES) under pressurized CO2 to characterize the dynamic behavior of conductivity and the dielectric relaxations of the ion host polymer matrix. It is revealed that there are three dielectric relaxation processes associated with: (I) the dipolar motions in the short oxyethylene side chains of P(EO/EM) (β); and (II) the segmental motion of the main chains comprising the polyether components (αfast, αslow). αslow is attributed to the slow α-relaxation of P(EO/EM) macromolecules, which is hindered by the strong coordination interactions with the ions. Two conduction processes are observed, σDC and σID, which are attributed, respectively, to the bulk conductivity and the interdomain conductivity. The temperature dependence of conductivity and relaxation processes reveals that αfast and αslow are strongly correlated with σDC and σID. The "in situ" BES measurements under pressurized CO2 indicate a fast decrease in σDC at the initial CO2 treatment time resulting from the decrease in the concentration of polyether-M(n+) complexes, which is driven by the CO2 permeation. The relaxation frequency (fR) of αslow at the initial CO2 treatment time increases and shows a steep rise with time with the same behavior of the αfast mode. It is demonstrated that the interactions between polyether chains of P(EO/EM) and cations in the polymer electrolyte layers embedded in Sa are probably weakened by the low permittivity of CO2 (ε = 1.08). Thus, the formation of ion pairs in the polymer electrolyte domains of P(EO/EM)-Sa occurs, with a corresponding reduction in the concentration of ion carriers.

  5. Electrical resistivity and thermal conductivity of liquid aluminum in the two-temperature state

    Science.gov (United States)

    Petrov, Yu V.; Inogamov, N. A.; Mokshin, A. V.; Galimzyanov, B. N.

    2018-01-01

    The electrical resistivity and thermal conductivity of liquid aluminum in the two-temperature state is calculated by using the relaxation time approach and structural factor of ions obtained by molecular dynamics simulation. Resistivity witin the Ziman-Evans approach is also considered to be higher than in the approach with previously calculated conductivity via the relaxation time. Calculations based on the construction of the ion structural factor through the classical molecular dynamics and kinetic equation for electrons are more economical in terms of computing resources and give results close to the Kubo-Greenwood with the quantum molecular dynamics calculations.

  6. Electrical conductivity and modulus formulation in zinc modified bismuth boro-tellurite glasses

    Science.gov (United States)

    Dhankhar, Sunil; Kundu, R. S.; Dult, Meenakshi; Murugavel, S.; Punia, R.; Kishore, N.

    2016-09-01

    The ac conductivity of zinc modified tellurium based quaternary glasses having composition 60 TeO2-10 B2O3-(30 - x) Bi2O3-x ZnO; x = 10, 15, 20, 25 and 30 has been investigated in the frequency range 10-1-105 Hz and in temperature range 483-593 K. Frequency and temperature dependent ac conductivity found to obey Jonscher power law modified by Almond-West. DC conductivity, crossover frequency and frequency exponent have been estimated from the fitting of the experimental data of conductivity with Jonscher power law modified by Almond-West. The ac conductivity and its frequency exponent have been analyzed by various theoretical models. In presently studied glasses ac conduction takes place via tunneling of overlapping large polaron tunneling. Activation energy is found to be increased with increase in zinc content and dc conduction takes place via variable range hopping proposed by Mott with some modification suggested by Punia et al. The value of the stretched exponent ( β) obtained by fitting of M^' ' }} reveals the presence of non-Debye type relaxation. Scaling spectra of ac conductivity and electric modulus collapse into a single master curve for all compositions and temperatures, reveals the presence of composition and temperature independent conduction and relaxation process in these glasses. Activation energy of conduction ( W) and electric modulus ( E R ) are nearly equal, indicating that polaron have to overcome the same energy barrier during conduction as well as relaxation processes.

  7. Microstructure, electrical conductivity and modulus spectra of CdI{sub 2} doped nanocomposite-electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Ranadip [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India); Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Roy, Debasish [Department of Mechanical Engineering, Jadavpur University, Jadavpur, Kolkata 700032 (India); Bhattacharya, Sanjib, E-mail: sanjib_ssp@yahoo.co.in [Department of Engineering Sciences and Humanities, Siliguri Institute of Technology, Darjeeeling 734009, West Bengal (India)

    2017-02-15

    Ionic conductivity and dielectric behavior of Ag{sub 2}O–CdI{sub 2}–CdO nanocomposite system have been studied. X-ray diffraction has been carried out to obtain the crystallite sizes and the growth of CdO dispersed in glass-matrices. Total conductivity of them shows thermally activated nature. It is observed that total conductivity decreases and corresponding activation energy for conduction follows opposite behavior. The high-frequency ac conductivity may correspond to a nonrandom, correlated and sub-diffusive motion of Ag{sup +} ions. Conductivity relaxation time is found to increase. The nature of scaling of the conductivity as well as modulus spectra indicates that the electrical relaxation of Ag{sup +} is temperature independent but depends upon composition.

  8. One-Dimensional Problem of a Conducting Viscous Fluid with One Relaxation Time

    Directory of Open Access Journals (Sweden)

    Angail A. Samaan

    2011-01-01

    Full Text Available We introduce a magnetohydrodynamic model of boundary-layer equations for conducting viscous fluids. This model is applied to study the effects of free convection currents with thermal relaxation time on the flow of a viscous conducting fluid. The method of the matrix exponential formulation for these equations is introduced. The resulting formulation together with the Laplace transform technique is applied to a variety problems. The effects of a plane distribution of heat sources on the whole and semispace are studied. Numerical results are given and illustrated graphically for the problem.

  9. Control of magnetic relaxation by electric-field-induced ferroelectric phase transition and inhomogeneous domain switching

    Energy Technology Data Exchange (ETDEWEB)

    Nan, Tianxiang; Emori, Satoru; Wang, Xinjun; Hu, Zhongqiang; Xie, Li; Gao, Yuan; Lin, Hwaider; Sun, Nian, E-mail: n.sun@neu.edu [Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts 02115 (United States); Peng, Bin; Liu, Ming, E-mail: mingliu@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, Xi' an Jiaotong University, Xi' an 710049 (China); Jiao, Jie; Luo, Haosu [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China); Budil, David [Department of Chemistry, Northeastern University, Boston, Massachusetts 02115 (United States); Jones, John G.; Howe, Brandon M.; Brown, Gail J. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio 45433 (United States)

    2016-01-04

    Electric-field modulation of magnetism in strain-mediated multiferroic heterostructures is considered a promising scheme for enabling memory and magnetic microwave devices with ultralow power consumption. However, it is not well understood how electric-field-induced strain influences magnetic relaxation, an important physical process for device applications. Here, we investigate resonant magnetization dynamics in ferromagnet/ferroelectric multiferroic heterostructures, FeGaB/PMN-PT and NiFe/PMN-PT, in two distinct strain states provided by electric-field-induced ferroelectric phase transition. The strain not only modifies magnetic anisotropy but also magnetic relaxation. In FeGaB/PMN-PT, we observe a nearly two-fold change in intrinsic Gilbert damping by electric field, which is attributed to strain-induced tuning of spin-orbit coupling. By contrast, a small but measurable change in extrinsic linewidth broadening is attributed to inhomogeneous ferroelastic domain switching during the phase transition of the PMN-PT substrate.

  10. HIGHLY RESOLVED MEASUREMENTS OF PERIODIC RADIAL ELECTRIC FIELD AND ASSOCIATED RELAXATIONS IN EDGE BIASING EXPERIMENTS

    Czech Academy of Sciences Publication Activity Database

    Peleman, P.; Xu, Y.; Spolaore, M.; Brotánková, Jana; Devynck, P.; Stöckel, Jan; Van Oost, G.; Boucher, C.

    363-365, č. 17 (2007), s. 638-642 ISSN 0022-3115. [ Plasma Surface Interactions in Controlled Fusion Devices/17th./. Hefei, 22.05.2007-26.05.2007] Institutional research plan: CEZ:AV0Z20430508 Keywords : Relaxations * Edge transport * Plasma flow * Radial electric fields Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.643, year: 2007

  11. Chapter A6. Section 6.3. Specific Electrical Conductance

    Science.gov (United States)

    Radtke, Dean B.; Davis, Jerri V.; Wilde, Franceska D.

    2005-01-01

    Electrical conductance is a measure of the capacity of a substance to conduct an electrical current. The specific electrical conductance (conductivity) of water is a function of the types and quantities of dissolved substances it contains, normalized to a unit length and unit cross section at a specified temperature. This section of the National Field Manual (NFM) describes U.S. Geological Survey (USGS) guidance and protocols for measurement of conductivity in ground and surface waters.

  12. Electrically conductive, immobilized bioanodes for microbial fuel cells

    International Nuclear Information System (INIS)

    Ganguli, R; Dunn, B

    2012-01-01

    The power densities of microbial fuel cells with yeast cells as the anode catalyst were significantly increased by immobilizing the yeast in electrically conductive alginate electrodes. The peak power densities measured as a function of the electrical conductivity of the immobilized electrodes show that although power increases with rising electrical conductivity, it tends to saturate beyond a certain point. Changing the pH of the anode compartment at that point seems to further increase the power density, suggesting that proton transport limitations and not electrical conductivity will limit the power density from electrically conductive immobilized anodes. (paper)

  13. Electrical spectroscopy studies of two new siloxanic proton conducting membranes

    Energy Technology Data Exchange (ETDEWEB)

    Di Noto, Vito [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, I-35135 Padova (Italy)]. E-mail: vito.dinoto@unipd.it; Vittadello, Michele [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, I-35135 Padova (Italy); Zago, Vanni [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, I-35135 Padova (Italy); Pace, Giuseppe [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, I-35135 Padova (Italy); Vidali, Maurizio [Dipartimento di Scienze Chimiche, Universita di Padova, Via Marzolo 1, I-35135 Padova (Italy)

    2006-01-20

    This contribution is focused on the conductivity study and the protonic transfer investigation of two new siloxanic membranes. The conductivity of the systems has been studied within the temperature range 5 deg. C {<=} T {<=} 145 deg. C, both for pristine and hydrated membranes. Membrane A has been hydrated up to 33.12% in weight, while in B up to 27.76%. The conductivity of these membranes has shown a temperature dependence of the Arrhenius type variable in the interval 1.6 x 10{sup -4} {<=} {sigma} {sub A} {<=} 2.3 x 10{sup -3} S cm{sup -1} and 1.3 x 10{sup -5} {<=} {sigma} {sub B} {<=} 2.9 x 10{sup -4} S cm{sup -1}, respectively, for A and B. In particular, conductivities of 2 x 10{sup -3} S cm{sup -1} (A) and of 2 x 10{sup -4} S cm{sup -1} (B) at 125 deg. C were observed. The conductivity mechanism was investigated by using broad band electrical spectroscopy in the region between 40 Hz and 10 MHz. This study, for both the materials has shown the presence at low frequencies (10{sup 2} {<=} f {sub {beta}} {<=} 10{sup 4} Hz) of {beta} relaxations related to the sulphonic side chain dynamics. The activation energy measured for this molecular dynamics is about {approx_equal}30 kJ mol{sup -1} and corresponds to the typical interaction energy associated with hydrogen bonding. Furthermore, it was observed that the activation energies determined from the conductivity measurements are 12 and 14 kJ mol{sup -1}, respectively, for A and B. This shows that the protonic conductivity is strongly influenced by the side chain dynamics and that the charge migration occurs through an ion hopping mechanism between different regions, consisting of micro-clusters of hydration water coordinated with the polar sulphonic groups of the side chains. The comparable activation energies and the values of the conductivity demonstrate that in these systems the conductivity is proportional to the concentration of the sulphonic groups. This shows also that these kinds of membranes, with a high

  14. Electrical spectroscopy studies of two new siloxanic proton conducting membranes

    International Nuclear Information System (INIS)

    Di Noto, Vito; Vittadello, Michele; Zago, Vanni; Pace, Giuseppe; Vidali, Maurizio

    2006-01-01

    This contribution is focused on the conductivity study and the protonic transfer investigation of two new siloxanic membranes. The conductivity of the systems has been studied within the temperature range 5 deg. C ≤ T ≤ 145 deg. C, both for pristine and hydrated membranes. Membrane A has been hydrated up to 33.12% in weight, while in B up to 27.76%. The conductivity of these membranes has shown a temperature dependence of the Arrhenius type variable in the interval 1.6 x 10 -4 ≤ σ A ≤ 2.3 x 10 -3 S cm -1 and 1.3 x 10 -5 ≤ σ B ≤ 2.9 x 10 -4 S cm -1 , respectively, for A and B. In particular, conductivities of 2 x 10 -3 S cm -1 (A) and of 2 x 10 -4 S cm -1 (B) at 125 deg. C were observed. The conductivity mechanism was investigated by using broad band electrical spectroscopy in the region between 40 Hz and 10 MHz. This study, for both the materials has shown the presence at low frequencies (10 2 ≤ f β ≤ 10 4 Hz) of β relaxations related to the sulphonic side chain dynamics. The activation energy measured for this molecular dynamics is about ≅30 kJ mol -1 and corresponds to the typical interaction energy associated with hydrogen bonding. Furthermore, it was observed that the activation energies determined from the conductivity measurements are 12 and 14 kJ mol -1 , respectively, for A and B. This shows that the protonic conductivity is strongly influenced by the side chain dynamics and that the charge migration occurs through an ion hopping mechanism between different regions, consisting of micro-clusters of hydration water coordinated with the polar sulphonic groups of the side chains. The comparable activation energies and the values of the conductivity demonstrate that in these systems the conductivity is proportional to the concentration of the sulphonic groups. This shows also that these kinds of membranes, with a high concentration of SO 3 H are necessary in order to obtain materials with a high protonic conductivity with the capacity to

  15. Nature of Dielectric Properties, Electric Modulus and AC Electrical Conductivity of Nanocrystalline ZnIn2Se4 Thin Films

    Science.gov (United States)

    El-Nahass, M. M.; Attia, A. A.; Ali, H. A. M.; Salem, G. F.; Ismail, M. I.

    2018-02-01

    The structural characteristics of thermally deposited ZnIn2Se4 thin films were indexed utilizing x-ray diffraction as well as scanning electron microscopy techniques. Dielectric properties, electric modulus and AC electrical conductivity of ZnIn2Se4 thin films were examined in the frequency range from 42 Hz to 106 Hz. The capacitance, conductance and impedance were measured at different temperatures. The dielectric constant and dielectric loss decrease with an increase in frequency. The maximum barrier height was determined from the analysis of the dielectric loss depending on the Giuntini model. The real part of the electric modulus revealed a constant maximum value at higher frequencies and the imaginary part of the electric modulus was characterized by the appearance of dielectric relaxation peaks. The AC electrical conductivity obeyed the Jonscher universal power law. Correlated barrier hopping model was the appropriate mechanism for AC conduction in ZnIn2Se4 thin films. Estimation of the density of states at the Fermi level and activation energy, for AC conduction, was carried out based on the temperature dependence of AC electrical conductivity.

  16. Behaviour of the Egyptian beach economic minerals during their electrical separation in relation to their electrical conductivity

    International Nuclear Information System (INIS)

    Khazback, A.E.; Soliman, F.A.S.

    1988-01-01

    The most important and strategic minerals in the Egyptian beach sands are monazite, zircon, rutile and ilmenite. Due to their importance, several flowsheets were designed for their separation economically. Electrostatic separation plays an important role in most of these flowsheets depending on the main differences between them concerning their electrical conductivity. This paper describes the design of a cell for the measurement of the electrical conductivities of these minerals. It also establishes a quantitative relationship between the electrical conductivity and the behaviour of these minerals during their electrical separation. A computer program was written to facilitate the calculation of the slope of the discharge curve from which the electrical conductivity or the reciprocal resistivity. Relaxation time and the data correlation coefficient for the tested minerals are obtained. For all the tests performed, the correlation coefficient value was found to be better than 99%. In general the electrical conductivity was shown to be a function of both temperature and grain size. It was found also that the presence of iron staining on the surface of monazite grains and inclusions in the zircon grains alters noticeably the bulk conductivity of the tested minerals

  17. Crater relaxation on Titan aided by low thermal conductivity sand infill

    Science.gov (United States)

    Schurmeier, Lauren R.; Dombard, Andrew J.

    2018-05-01

    Titan's few impact craters are currently many hundreds of meters shallower than the depths expected. Assuming these craters initially had depths equal to that of similar-size fresh craters on Ganymede and Callisto (moons of similar size, composition, and target lithology), then some process has shallowed them over time. Since nearly all of Titan's recognized craters are located within the arid equatorial sand seas of organic-rich dunes, where rain is infrequent, and atmospheric sedimentation is expected to be low, it has been suggested that aeolian infill plays a major role in shallowing the craters. Topographic relaxation at Titan's current heat flow was previously assumed to be an unimportant process on Titan due to its low surface temperature (94 K). However, our estimate of the thermal conductivity of Titan's organic-rich sand is remarkably low (0.025 W m-1 K-1), and when in thick deposits, will result in a thermal blanketing effect that can aid relaxation. Here, we simulate the relaxation of Titan's craters Afekan, Soi, and Sinlap including thermal effects of various amounts of sand inside and around Titan's craters. We find that the combination of aeolian infill and subsequent relaxation can produce the current crater depths in a geologically reasonable period of time using Titan's current heat flow. Instead of needing to fill completely the missing volume with 100% sand, only ∼62%, ∼71%, and ∼97%, of the volume need be sand at the current basal heat flux for Afekan, Soi, and Sinlap, respectively. We conclude that both processes are likely at work shallowing these craters, and this finding contributes to why Titan overall lacks impact craters in the arid equatorial regions.

  18. The equations of the thermomechanics of electrically conducting nonferromagnetic bodies taking account of structural transformations

    International Nuclear Information System (INIS)

    Nagirnyi, T.S.

    1993-01-01

    Studies of the coupled processes in electrically conducting nonferromagnetic viscoelastic bodies usually begin with a system of equations that accounts for the influence of rheology on the mechanical and temperature fields. In this context, rheology is understood as the course of certain internal processes in the body that are reflected when the relaxation time and the defects of thermomechanical moduli are specified. In this work, the methods of continuum mechanics are used to state a system of equations for the quantitative description of coupled mechanical, thermal, and electromagnetic processes taking account of structural transformations in the context of the model of a rheologically simple electrically conducting nonferromagnetic body

  19. Ac conductivity and relaxation mechanism in Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Singh, A K; Barik, Subrat K [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302 (India); Choudhary, R N.P. , [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721 302 (India); Mahapatra, P K [Department of Physics, Vidyasagar University, Midnapore 721 102 (India)

    2009-06-24

    The ac conductivity and relaxation mechanism in Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} ceramics have been investigated systematically. A high-temperature solid-state reaction technique was used to synthesize the compound. The formation of the compound was checked by an X-ray diffraction (XRD) technique. The dielectric permittivity and the loss tangent of the sample were measured in a frequency range from 1 kHz to 1 MHz at different temperatures (30-500 deg. C). A study on dielectric properties reveals the electrical relaxation phenomenon occurs in the material. The activation energy was calculated from the temperature variation of dc conductivity. Studies of frequency and temperature dependence of ac conductivity of the compound suggest that conduction process in the material is thermally activated.

  20. Electrical conductivity in AlN-CuO composites

    International Nuclear Information System (INIS)

    Azad, A.M.; Cheng, H.S.

    1999-01-01

    Water vapor is an important constituent of any gas and in many applications is regarded as a contaminant that needs to be monitored and controlled. It is also immense importance in the pyrohydrolytic reaction of new exotic non-oxide engineering ceramics such as silicon carbide and silicon nitride. Together with CO/sub 2/, water vapor is the largest contributor to the 'greenhouse' effect. Thus there is a need for greater attention to humidity sensor selection for a given application. AlN-CuO composites (2% is equal or < CuO is equal or < 50% by weight) have been studied to exploit them as novel humidity sensors over wide ranges of moisture levels and temperature. Development of benign microstructure with open porosity has been attempted by varying the composition and firing conditions. The impedance data acquired on the composites over the frequency range 5 Hz to 13 MHz, revealed a bulk response in the form of a single semicircular relaxation in the complex Z/sup */-plane. A systematic variation of electrical conductivity with CuO content in the composites has been explained in the light of percolation theory. (author)

  1. Structure, Raman, dielectric behavior and electrical conduction mechanism of strontium titanate

    Science.gov (United States)

    Trabelsi, H.; Bejar, M.; Dhahri, E.; Graça, M. P. F.; Valente, M. A.; Khirouni, K.

    2018-05-01

    Strontium titanate was prepared by solid-state reaction method. According to the XRD, it was single phase and has a cubic perovskite structure. The Raman spectroscopic investigation was carried out at room-temperature, and the second-order Raman modes were observed. By employing impedance spectroscopy, the dielectric relaxation and electrical properties were investigated over the temperature range of 500-700 K at various frequencies. The activation energies evaluated from dielectric and modulus studies are in good agreement and these values are attributed to the bulk relaxation. The impedance data were well fitted to an (R1//C1)-(R2//CPE1) equivalent electrical circuit. It could be concluded that the grain boundaries are more resistive and capacitive than the grains. The ac conductivity was found to follow the Jonscher's universal dynamic law ωS and the correlated barrier hopping model (CBH) has been proposed to describe the conduction mechanism.

  2. High electric field conduction in low-alkali boroaluminosilicate glass

    Science.gov (United States)

    Dash, Priyanka; Yuan, Mengxue; Gao, Jun; Furman, Eugene; Lanagan, Michael T.

    2018-02-01

    Electrical conduction in silica-based glasses under a low electric field is dominated by high mobility ions such as sodium, and there is a transition from ionic transport to electronic transport as the electric field exceeds 108 V/m at low temperatures. Electrical conduction under a high electric field was investigated in thin low-alkali boroaluminosilicate glass samples, showing nonlinear conduction with the current density scaling approximately with E1/2, where E is the electric field. In addition, thermally stimulated depolarization current (TSDC) characterization was carried out on room-temperature electrically poled glass samples, and an anomalous discharging current flowing in the same direction as the charging current was observed. High electric field conduction and TSDC results led to the conclusion that Poole-Frenkel based electronic transport occurs in the mobile-cation-depleted region adjacent to the anode, and accounts for the observed anomalous current.

  3. Electrical conductivity modeling in fractal non-saturated porous media

    Science.gov (United States)

    Wei, W.; Cai, J.; Hu, X.; Han, Q.

    2016-12-01

    The variety of electrical conductivity in non-saturated conditions is important to study electric conduction in natural sedimentary rocks. The electrical conductivity in completely saturated porous media is a porosity-function representing the complex connected behavior of single conducting phases (pore fluid). For partially saturated conditions, the electrical conductivity becomes even more complicated since the connectedness of pore. Archie's second law is an empirical electrical conductivity-porosity and -saturation model that has been used to predict the formation factor of non-saturated porous rock. However, the physical interpretation of its parameters, e.g., the cementation exponent m and the saturation exponent n, remains questionable. On basis of our previous work, we combine the pore-solid fractal (PSF) model to build an electrical conductivity model in non-saturated porous media. Our theoretical porosity- and saturation-dependent models contain endmember properties, such as fluid electrical conductivities, pore fractal dimension and tortuosity fractal dimension (representing the complex degree of electrical flowing path). We find the presented model with non-saturation-dependent electrical conductivity datasets indicate excellent match between theory and experiments. This means the value of pore fractal dimension and tortuosity fractal dimension change from medium to medium and depends not only on geometrical properties of pore structure but also characteristics of electrical current flowing in the non-saturated porous media.

  4. Long-persistent relaxation and frozen conductivity in Zn Se with radiation-induced defects

    International Nuclear Information System (INIS)

    Blajcu, A.I.; Djuadi, D.; Casian, V.A.; Moseiciuc, G.S.; Nedeoglo, D.D.

    1993-01-01

    In an n-Zn Se crystals which have been preliminarily annealed in liquid Zn and then exposed to irradiation by a flow of electrons with an energy of E = 1.3 MeV and a dose of irradiation from 2.73 x 10 16 to 5.19 x 10 17 el/cm 2 , phenomena of a long-persistent conductivity relaxation (LCR) and frozen conduction (FC) at 77 K have been brought out and examined. It has been shown that the character of the relaxation processes at small doses of irradiation is rather well explained by the two-barrier model of an inhomogeneous semiconductor which represents a low-resistance matrix with high-resistance inclusions (clusters). As the dose of irradiation increases the overlapping of regions of space charge which surrounds the high-resistance inclusions increases and the considered model of high-resistance inclusions must be changed at D = 3 x 10 17 el/cm 2 into of a random potential relief. The temperature quenching of FC is explain in the assumption that, with the temperature increase, the drift and the recombination barriers decrease simultaneously as the result of variation of the sizes of space charge region surrounding the clusters. (Author)

  5. Hot-electron effect in spin relaxation of electrically injected electrons in intrinsic Germanium.

    Science.gov (United States)

    Yu, T; Wu, M W

    2015-07-01

    The hot-electron effect in the spin relaxation of electrically injected electrons in intrinsic germanium is investigated by the kinetic spin Bloch equations both analytically and numerically. It is shown that in the weak-electric-field regime with E ≲ 0.5 kV cm(-1), our calculations have reasonable agreement with the recent transport experiment in the hot-electron spin-injection configuration (2013 Phys. Rev. Lett. 111 257204). We reveal that the spin relaxation is significantly enhanced at low temperature in the presence of weak electric field E ≲ 50 V cm(-1), which originates from the obvious center-of-mass drift effect due to the weak electron-phonon interaction, whereas the hot-electron effect is demonstrated to be less important. This can explain the discrepancy between the experimental observation and the previous theoretical calculation (2012 Phys. Rev. B 86 085202), which deviates from the experimental results by about two orders of magnitude at low temperature. It is further shown that in the strong-electric-field regime with 0.5 ≲ E ≲ 2 kV cm(-1), the spin relaxation is enhanced due to the hot-electron effect, whereas the drift effect is demonstrated to be marginal. Finally, we find that when 1.4 ≲ E ≲ 2 kV cm(-1) which lies in the strong-electric-field regime, a small fraction of electrons (≲5%) can be driven from the L to Γ valley, and the spin relaxation rates are the same for the Γ and L valleys in the intrinsic sample without impurity. With the negligible influence of the spin dynamics in the Γ valley to the whole system, the spin dynamics in the L valley can be measured from the Γ valley by the standard direct optical transition method.

  6. Effective electrical and thermal conductivity of multifilament twisted superconductors

    International Nuclear Information System (INIS)

    Chechetkin, V.R.

    2013-01-01

    The effective electrical and thermal conductivity of composite wire with twisted superconducting filaments embedded into normal metal matrix is calculated using the extension of Bruggeman method. The resistive conductivity of superconducting filaments is described in terms of symmetric tensor, whereas the conductivity of a matrix is assumed to be isotropic and homogeneous. The dependence of the resistive electrical conductivity of superconducting filaments on temperature, magnetic field, and current density is implied to be parametric. The resulting effective conductivity tensor proved to be non-diagonal and symmetric. The non-diagonal transverse–longitudinal components of effective electrical conductivity tensor are responsible for the redistribution of current between filaments. In the limits of high and low electrical conductivity of filaments the transverse effective conductivity tends to that of obtained previously by Carr. The effective thermal conductivity of composite wires is non-diagonal and radius-dependent even for the isotropic and homogeneous thermal conductivities of matrix and filaments.

  7. Low frequency dielectric relaxation processes and ionic conductivity of montmorillonite clay nanoparticles colloidal suspension in poly(vinyl pyrrolidone−ethylene glycol blends

    Directory of Open Access Journals (Sweden)

    2008-11-01

    Full Text Available The dielectric dispersion behaviour of montmorillonite (MMT clay nanoparticles colloidal suspension in poly(vinyl pyrrolidone-ethylene glycol (PVP-EG blends were investigated over the frequency range 20 Hz to 1 MHz at 30°C. The 0, 1, 2, 3, 5 and 10 wt% MMT clay concentration of the weight of total solute (MMT+PVP were prepared in PVP-EG blends using EG as solvent. The complex relative dielectric function, alternating current (ac electrical conductivity, electric modulus and impedance spectra of these materials show the relaxation processes corresponding to the micro-Brownian motion of PVP chain, ion conduction and electrode polarization phenomena. The real part of ac conductivity spectra of these materials obeys Jonscher power law σ′(ω =σdc + Aωn in upper frequency end of the measurement, whereas dispersion in lower frequency end confirms the presence of electrode polarization effect. It was observed that the increase of clay concentration in the PVP-EG blends significantly increases the ac conductivity values, and simultaneously reduces the ionic conductivity relaxation time and electric double layer relaxation time, which suggests that PVP segmental dynamics and ionic motion are strongly coupled. The intercalation of EG structures in clay galleries and exfoliation of clay sheets by adsorption of PVP-EG structures on clay surfaces are discussed by considering the hydrogen bonding interactions between the hydroxyl group (–OH of EG molecules, carbonyl group (C=O of PVP monomer units, and the hydroxylated aluminate surfaces of the MMT clay particles. Results suggest that the colloidal suspension of MMT clay nano particles in the PVP-EG blends provide a convenient way to obtain an electrolyte solution with tailored electrical conduction properties.

  8. Electrical conduction in solid materials physicochemical bases and possible applications

    CERN Document Server

    Suchet, J P

    2013-01-01

    Electrical Conduction in Solid Materials (Physicochemical Bases and Possible Applications) investigates the physicochemical bases and possible applications of electrical conduction in solid materials, with emphasis on conductors, semiconductors, and insulators. Topics range from the interatomic bonds of conductors to the effective atomic charge in conventional semiconductors and magnetic transitions in switching semiconductors. Comprised of 10 chapters, this volume begins with a description of electrical conduction in conductors and semiconductors, metals and alloys, as well as interatomic bon

  9. Strain relaxation and ambipolar electrical transport in GaAs/InSb core-shell nanowires.

    Science.gov (United States)

    Rieger, Torsten; Zellekens, Patrick; Demarina, Natalia; Hassan, Ali Al; Hackemüller, Franz Josef; Lüth, Hans; Pietsch, Ullrich; Schäpers, Thomas; Grützmacher, Detlev; Lepsa, Mihail Ion

    2017-11-30

    The growth, crystal structure, strain relaxation and room temperature transport characteristics of GaAs/InSb core-shell nanowires grown using molecular beam epitaxy are investigated. Due to the large lattice mismatch between GaAs and InSb of 14%, a transition from island-based to layer-like growth occurs during the formation of the shell. High resolution transmission electron microscopy in combination with geometric phase analyses as well as X-ray diffraction with synchrotron radiation are used to investigate the strain relaxation and prove the existence of different dislocations relaxing the strain on zinc blende and wurtzite core-shell nanowire segments. While on the wurtzite phase only Frank partial dislocations are found, the strain on the zinc blende phase is relaxed by dislocations with perfect, Shockley partial and Frank partial dislocations. Even for ultrathin shells of about 2 nm thickness, the strain caused by the high lattice mismatch between GaAs and InSb is relaxed almost completely. Transfer characteristics of the core-shell nanowires show an ambipolar conductance behavior whose strength strongly depends on the dimensions of the nanowires. The interpretation is given based on an electronic band profile which is calculated for completely relaxed core/shell structures. The peculiarities of the band alignment in this situation implies simultaneously occupied electron and hole channels in the InSb shell. The ambipolar behavior is then explained by the change of carrier concentration in both channels by the gate voltage.

  10. Method of forming an electrically conductive cellulose composite

    Science.gov (United States)

    Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Woodward, Jonathan [Ashtead, GB

    2011-11-22

    An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

  11. Electrical conductivity measurement on DKDP Crystals with different deuterated degrees

    International Nuclear Information System (INIS)

    Liu, Baoan; Yin, Xin; Xu, Mingxia; Ji, Shaohua; Zhu, Lili; Zhang, Lisong; Sun, Xun; Xu, Xinguang; Zhao, Minglei; Zhang, Qinghua

    2012-01-01

    Ten DKDP single crystals with deuterated degrees ranging from 0 to 90 % were grown by a rapid growth method. The electrical conductivities of these crystals were measured along a and c directions at room temperature. The electrical conductivity increases with the increase for deuterium content. Also, the electrical conductivities of certain crystals were measured at various temperatures ranging from 20 to 130 C. The values of activation energy decrease as the increase of deuterium content. The present study indicates that the deuterium tunneling frequency is smaller than that of hydrogen, which may be the reason why the variation of electrical conductivity happens after the substitution of hydrogen for deuterium in KDP crystal. (orig.)

  12. Electrical conduction in graphene and nanotubes

    CERN Document Server

    Fujita, Shigeji

    2013-01-01

    Written in a self-contained manner, this textbook allows both advanced students and practicing applied physicists and engineers to learn the relevant aspects from the bottom up. All logical steps are laid out without omitting steps.The book covers electrical transport properties in carbon based materials by dealing with statistical mechanics of carbon nanotubes and graphene ? presenting many fresh and sometimes provoking views. Both second quantization and superconductivity are covered and discussed thoroughly. An extensive list of references is given in the end of each chapter, while derivati

  13. Wet method for measuring starch gelatinization temperature using electrical conductivity.

    Science.gov (United States)

    Morales-Sanchez, E; Figueroa, J D C; Gaytan-Martínez, M

    2009-09-01

    The objective of the present study was to develop a method for obtaining the gelatinization temperature of starches by using electrical conductivity. Native starches from corn, rice, potato, and wheat were prepared with different proportions of water and heated from room temperature to 90 degrees C, in a device especially designed for monitoring the electrical conductivity as a function of temperature. The results showed a linear trend of the electrical conductivity with the temperature until it reaches the onset gelatinization temperature. After that point, the electrical conductivity presented an increment or decrement depending on the water content in the sample and it was related to starch swelling and gelatinization phenomena. At the end gelatinization temperature, the conductivity becomes stable and linear, indicating that there are no more changes of phase. The starch gelatinization parameter, which was evaluated in the 4 types of starches using the electrical conductivity, was compared with those obtained by using differential scanning calorimeter (DSC). The onset temperature at which the electrical conductivity increased or decreased was found to be similar to that obtained by DSC. Also, the final temperature at which the electrical conductivity returned to linearity matched the end gelatinization temperature of the DSC. Further, a wet method for measuring the onset, peak, and end gelatinization temperatures as a function of temperature using the electrical conductivity curves is presented for a starch-water suspension.

  14. Method of imaging the electrical conductivity distribution of a subsurface

    Science.gov (United States)

    Johnson, Timothy C.

    2017-09-26

    A method of imaging electrical conductivity distribution of a subsurface containing metallic structures with known locations and dimensions is disclosed. Current is injected into the subsurface to measure electrical potentials using multiple sets of electrodes, thus generating electrical resistivity tomography measurements. A numeric code is applied to simulate the measured potentials in the presence of the metallic structures. An inversion code is applied that utilizes the electrical resistivity tomography measurements and the simulated measured potentials to image the subsurface electrical conductivity distribution and remove effects of the subsurface metallic structures with known locations and dimensions.

  15. Electric and electrothermal conductivity of planetary ionospheres

    International Nuclear Information System (INIS)

    Pavlov, A.V.

    1984-01-01

    In the first, second and third approximations of expansion of the Chapman-Enskog method in Sonin polynomials, an explicit form is found of coefficients of electrical and electrothermal electron condituctjvity in a magnetic field in a multicomponent ionosphere with allowance for the electron temperature difference from the heavy component temperature. The generic expressions for the electron transport coefficients are reduced to the form suitable for practical applications. In the first approximation of expansion in Sonin polynomials, the equations are derived for determining the ion diffusion velocities in a magnetic field in a multicomponent gas mixtures. +he approximating expressions for frequencies of electron collisions with main neutral components of planet upper atmospheres are refined. In the first, second and third approximations the equations are derived for determining velocities of ambipolar ion diffusion in a multicomponent ionosphere without a magnetic field (or parallel to it). The explicit form of the electron thermodiffusion factor, being a part of these equations, has been found

  16. An experimental investigation of electrical conductivities in ...

    Indian Academy of Sciences (India)

    by HIOKI 3522 LCR/Z Meter (Japan). The a.c. conductivities were measured to depict the. Arrhenius behaviour of solid specimen with temperature variation setup and HIOKI 3522 LCR/Z Meter by using two-probe method. The temperature variation of a.c. con- ductivities were recorded by Tektronix DTM 900 Thermo-.

  17. Deducting the temperature dependence of the structural relaxation time in equilibrium far below the nominal Tg by aging the decoupled conductivity relaxation to equilibrium.

    Science.gov (United States)

    Wojnarowska, Z; Ngai, K L; Paluch, M

    2014-05-07

    Using broadband dielectric spectroscopy we investigate the changes in the conductivity relaxation times τσ observed during the physical aging of the protic ionic conductor carvedilol dihydrogen phosphate (CP). Due to the large decoupling of ion diffusion from host molecule reorientation, the ion conductivity relaxation time τσ(Tage,tage) can be directly measured at temperatures Tage below Tg for exceedingly long aging times tage till τσ(Tage,tage) has reached the equilibrium value τσ(eq)(Tage). The dependence of τσ(Tage,tage) on tage is well described by the stretched exponential function, τσ(Tage, tage) = Aexp[-((tage)/(τage(Tage)))(β)] + τσ(eq)(Tage), where β is a constant and τage(Tage) can be taken as the structural α-relaxation time of the equilibrium liquid at T = Tage. The value of τσ(eq)(Tage) obtained after 63 days long annealing of CP, deviates from the Vogel-Fulcher-Tammann-Hesse (VFTHσ) dependence of τσ(T) determined from data taken above Tg and extrapolated down to Tage. Concurrently, τage(Tage) also deviates from the Vogel-Fulcher-Tammann-Hesse (VFTHα) dependence. The results help to answer the longstanding question of whether the VFTH dependence of τσ(T) as well as the structural α-relaxation time τα(T) holds or not in the equilibrium liquid state far below Tg.

  18. Ambient effects on the electrical conductivity of carbon nanotubes

    DEFF Research Database (Denmark)

    Roch, Aljoscha; Greifzu, Moritz; Roch Talens, Esther

    2015-01-01

    We show that the electrical conductivity of single walled carbon nanotubes (SWCNT) networks is affected by oxygen and air humidity under ambient conditions by more than a magnitude. Later, we intentionally modified the electrical conductivity by functionalization with iodine and investigated...

  19. Electrical conductivity of free-standing mesoporous silicon thin films

    International Nuclear Information System (INIS)

    Khardani, M.; Bouaicha, M.; Dimassi, W.; Zribi, M.; Aouida, S.; Bessais, B.

    2006-01-01

    The effective electrical conductivity of free-standing p + -type porous silicon layers having porosities ranging from 30% to 80% was studied at both experimental and theoretical sides. An Effective Medium Approximation (EMA) model was used as a theoretical support. The porous silicon (PS) films were prepared by the electrochemical etching method for different values of the anodic current density. In order to model the PS electrical conductivity, the free-standing porous layer was assumed to be formed of three phases; vacuum, oxide and Si nanocrystallites. The analytical expression of the electrical conductivity of the Si nanocrystallites was established using the quantum confinement theory. This enables us to correlate the electrical conductivity of the mesoporous film to the value of the effective band gap energy estimated from the absorption coefficient. A perfect agreement between the theoretical and the experimental electrical conductivity values was obtained for all prospected PS porosities

  20. The electric conductivity of some forms of sintered synthetic zeolites

    International Nuclear Information System (INIS)

    Susic, M.; Petrovic, V.; Ristic, M.; Petranovic, N.

    1978-01-01

    Some forms of synthetic zeolites were sintered and their electric conductivity was measured. The conductivity was observed in correlation with the conductivity of non-sintered pressed samples. Also the change in microstructural constituents in the course of the process of sintering was observed with an optical microscope. It has been found that there is a considerable change in conductivity due to sintering as well as a change in the activation energy for conduction. Also the porosity is noticeably changed. A marked affect of the nature of counter ions on the electric conductivity is shown

  1. Electrically Conductive and Protective Coating for Planar SOFC Stacks

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jung-Pyung; Stevenson, Jeffry W.

    2017-12-04

    Ferritic stainless steels are preferred interconnect materials for intermediate temperature SOFCs because of their resistance to oxidation, high formability and low cost. However, their protective oxide layer produces Cr-containing volatile species at SOFC operating temperatures and conditions, which can cause cathode poisoning. Electrically conducting spinel coatings have been developed to prevent cathode poisoning and to maintain an electrically conductive pathway through SOFC stacks. However, this coating is not compatible with the formation of stable, hermetic seals between the interconnect frame component and the ceramic cell. Thus, a new aluminizing process has been developed by PNNL to enable durable sealing, prevent Cr evaporation, and maintain electrical insulation between stack repeat units. Hence, two different types of coating need to have stable operation of SOFC stacks. This paper will focus on the electrically conductive coating process. Moreover, an advanced coating process, compatible with a non-electrically conductive coating will be

  2. Thermal and Electrical Conductivities of a Three-Dimensional Ideal Anyon Gas with Fractional Exclusion Statistics

    International Nuclear Information System (INIS)

    Qin Fang; Wen Wen; Chen Ji-Sheng

    2014-01-01

    The thermal and electrical transport properties of an ideal anyon gas within fractional exclusion statistics are studied. By solving the Boltzmann equation with the relaxation-time approximation, the analytical expressions for the thermal and electrical conductivities of a three-dimensional ideal anyon gas are given. The low-temperature expressions for the two conductivities are obtained by using the Sommerfeld expansion. It is found that the Wiedemann—Franz law should be modified by the higher-order temperature terms, which depend on the statistical parameter g for a charged anyon gas. Neglecting the higher-order terms of temperature, the Wiedemann—Franz law is respected, which gives the Lorenz number. The Lorenz number is a function of the statistical parameter g. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  3. Assembly for electrical conductivity measurements in the piston cylinder device

    Science.gov (United States)

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  4. Numerical Modeling of Electrical Contact Conductance of Rough Bodies

    Directory of Open Access Journals (Sweden)

    M. V. Murashov

    2015-01-01

    Full Text Available Since the beginning of the 20th century to the present time, efforts have been made to develop a model of the electrical contact conductance. The development of micro- and nanotechnologies make contact conductance problem more essential. To conduct borrowing from a welldeveloped thermal contact conductance models on the basis of thermal and electrical conductivity analogy is often not possible due to a number of fundamental differences. While some 3Dmodels of rough bodies deformation have been developed in one way or another, a 3D-model of the electrical conductance through rough bodies contact is still not. A spatial model of electrical contact of rough bodies is proposed, allows one to calculate the electrical contact conductance as a function of the contact pressure. Representative elements of the bodies are parallelepipeds with deterministic roughness on the contacting surfaces. First the non-linear elastic-plastic deformation of rough surface under external pressure is solved using the finite element software ANSYS. Then the solution of electrostatic problem goes on the same finite element mesh. Aluminum AD1 is used as the material of the contacting bodies with properties that account for cold work hardening of the surface. The numerical model is built within the continuum mechanics and nanoscale effects are not taken into account. The electrical contact conductance was calculated on the basis of the concept of electrical resistance of the model as the sum of the electrical resistances of the contacting bodies and the contact itself. It was assumed that there is no air in the gap between the bodies. The dependence of the electrical contact conductance on the contact pressure is calculated as well as voltage and current density distributions in the contact bodies. It is determined that the multi-asperity contact mode, adequate to real roughness, is achieved at pressures higher than 3MPa, while results within the single contact spot are

  5. Electrical conductivity of conductive carbon blacks: influence of surface chemistry and topology

    International Nuclear Information System (INIS)

    Pantea, Dana; Darmstadt, Hans; Kaliaguine, Serge; Roy, Christian

    2003-01-01

    Conductive carbon blacks from different manufacturers were studied in order to obtain some insight into the relation between their electrical conductivity and their surface properties. The surface chemistry was studied by X-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectroscopy (SIMS), whereas the topology of the carbon black surface was investigated using low-pressure nitrogen adsorption. All these techniques yield information on the graphitic character of the surface. In general, the electrical conductivity of the conductive blacks increases with the graphitic character of the surface. For low surface area conductive blacks, the electrical conductivity correlates well with the surface chemistry. In the case of the XPS and SIMS data, this correlation is also valid when other types of carbon blacks such as thermal and furnace blacks are included, confirming the determining influence of the carbon black surface chemistry on the electrical conductivity

  6. Electrical conductivity and magnetic permeability measurement of case hardened steels

    Science.gov (United States)

    Tian, Yong

    2015-03-01

    For case carburized steels, electrical conductivity and magnetic permeability profiles are needed to develop model-based case depth characterization techniques for the purpose of nondestructive quality control. To obtain fast and accurate measurement of these material properties, four-point potential drop approaches are applied on circular-shaped discs cut from steel rings with different case depths. First, a direct current potential drop (DCPD) approach is applied to measure electrical conductivity. Subsequently, an alternating current potential drop (ACPD) approach is used to measure magnetic permeability. Practical issues in measurement design and implementation are discussed. Depth profiles of electrical conductivity and magnetic permeability are reported.

  7. Enhanced AC conductivity and dielectric relaxation properties of polypyrrole nanoparticles irradiated with Ni12+ swift heavy ions

    International Nuclear Information System (INIS)

    Hazarika, J.; Kumar, A.

    2014-01-01

    In this paper, we report the 160 MeV Ni 12+ swift heavy ions (SHIs) irradiation effects on AC conductivity and dielectric relaxation properties of polypyrrole (PPy) nanoparticles in the frequency range of 42 Hz–5 MHz. Four ion fluences of 5 × 10 10 , 1 × 10 11 , 5 × 10 11 and 1 × 10 12 ions/cm 2 have been used for the irradiation purpose. Transport properties in the pristine and irradiated PPy nanoparticles have been investigated with permittivity and modulus formalisms to study the polarization effects and conductivity relaxation. With increasing ion fluence, the relaxation peak in imaginary modulus (M ″ ) plots shifts toward high frequency suggesting long range motion of the charge carriers. The AC conductivity studies suggest correlated barrier hopping as the dominant transport mechanism. The hopping distance (R ω ) of the charge carriers decreases with increasing the ion fluence. Binding energy (W m ) calculations depict that polarons are the dominant charge carriers

  8. Enhancement in electrical conductivity of Li 2 O

    Indian Academy of Sciences (India)

    The study of electrical conductivity of 30Li2O : (70 – ) B2O3 : V2O5 glass samples has been carried out. The results have been explained by dividing the temperature range into two regions. In region I, conductivity shows Arrhenius behaviour for all the samples. The conductivity increases with addition of V2O5.

  9. Nuclear magnetic resonance and electrical conductivity measurements of diffusion and disorder in LiBr

    International Nuclear Information System (INIS)

    Hamann, H.; Reininghaus, J.; Richtering, H.

    1980-01-01

    Electrical conductivity and nuclear magnetic relaxation rates were measured with pure and doped LiBr between 400 K and the melting point (824 K). Prevalent intrinsic disorder was observed down to 470 K. The degree of thermal disorder is 5 X 10 -7 at 470 K and 5 X 10 -3 at the melting point. From the relaxation rates of 7 Li, which are caused by Li-diffusion and nuclear dipole interaction, mean jump frequencies of the cations are derived. Conductivities calculated from these frequencies for a jump process via neighbouring cation vacancies are in perfect agreement with directly measured conductivities. From relaxation rates of 81 Br with MgBr 2 -doped crystals jump frequencies of vacancies were obtained which are again in good agreement with those derived from the conductivity data. From motional narrowing of the 81 Br absorption line the jump frequency of the anions is obtained, which is much smaller than for the cations. Since this motional narrowing is not influenced by any doping, it is concluded that anion transport mainly occurs via pairs of cation and anion vacancies. (Auth.)

  10. Pressure and graphite effects on electrical conductivity in pyroxene

    Science.gov (United States)

    Wang, D.; Liu, T.; Shen, K.; Li, B.

    2017-12-01

    The geophysical observations including magnetotelluric (MT) and geomagnetic deep sounding show the distribution of electrical conductivity in the Earth's interior. The laboratory-based conductivity measurements of minerals and rocks are usually used to interpret the geophysical observations. Pyroxene is the second most abundant components in the upper mantle, and the electrical conductivity of pyroxene is important to understanding the bulk electrical conductivity. The electrical conductivity of a mineral is affected by many factors, such as its chemical composition, temperature, pressure. Here we report the effects of pressure and graphite on the electrical conductivity of pyroxene and applied to interpretation of MT observation. The starting materials are natural of orthopyroxene and clinopyroxe crystals. A powder sample with grain size 10 um was packed in a Mo capsule and hot-pressed at high pressures and temperatures using a 1000-ton Walker-type uniaxial split-cylinder apparatus. A mixture of pyroxene and a few percent of diamond was annealed at high pressure and temperature. All the hot-pressed samples before and after electrical conductivity measurements, were characterized by scanning electron microscopy, Fourier-Transform Infrared and Raman spectroscopy. High pressure conductivity experiments were carried out in a Walker-type multi-anvil apparatus using a 14/8 assembly. We use a Solartron 1260 Impedance/Gain -phase analyzer with 1V applied voltage within a frequency range of 1M-0.1 Hz to collect data. Complex impedance data on were collected in several heating and cooling cycles The electrical conductivity of pyroxene was made at 4,7,10 GPa, and electrical conductivity of the graphite-bearing pyroxene was measured at 4GPa. The results show the electrical conductivity decrease with the increasing of pressure, which may correspond to the transform from orthopyroxene to clinopyroxene. The results can be used to explain a drop of the electrical conductivity in

  11. Nuclear Spin Lattice Relaxation and Conductivity Studies of the Non-Arrhenius Conductivity Behavior in Lithium Fast Ion Conducting Sulfide Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Benjamin Michael [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    As time progresses, the world is using up more of the planet's natural resources. Without technological advances, the day will eventually arrive when these natural resources will no longer be sufficient to supply all of the energy needs. As a result, society is seeing a push for the development of alternative fuel sources such as wind power, solar power, fuel cells, and etc. These pursuits are even occurring in the state of Iowa with increasing social pressure to incorporate larger percentages of ethanol in gasoline. Consumers are increasingly demanding that energy sources be more powerful, more durable, and, ultimately, more cost efficient. Fast Ionic Conducting (FIC) glasses are a material that offers great potential for the development of new batteries and/or fuel cells to help inspire the energy density of battery power supplies. This dissertation probes the mechanisms by which ions conduct in these glasses. A variety of different experimental techniques give a better understanding of the interesting materials science taking place within these systems. This dissertation discusses Nuclear Magnetic Resonance (NMR) techniques performed on FIC glasses over the past few years. These NMR results have been complimented with other measurement techniques, primarily impedance spectroscopy, to develop models that describe the mechanisms by which ionic conduction takes place and the dependence of the ion dynamics on the local structure of the glass. The aim of these measurements was to probe the cause of a non-Arrhenius behavior of the conductivity which has been seen at high temperatures in the silver thio-borosilicate glasses. One aspect that will be addressed is if this behavior is unique to silver containing fast ion conducting glasses. more specifically, this study will determine if a non-Arrhenius correlation time, τ, can be observed in the Nuclear Spin Lattice Relaxation (NSLR) measurements. If so, then can this behavior be modeled with a new single

  12. Thermal and electrical conductivities of Cd-Zn alloys

    International Nuclear Information System (INIS)

    Saatci, B; Ari, M; Guenduez, M; Meydaneri, F; Bozoklu, M; Durmus, S

    2006-01-01

    The composition and temperature dependences of the thermal and electrical conductivities of three different Cd-Zn alloys have been investigated in the temperature range of 300-650 K. Thermal conductivities of the Cd-Zn alloys have been determined by using the radial heat flow method. It has been found that the thermal conductivity decreases slightly with increasing temperature and the data of thermal conductivity are shifting together to the higher values with increasing Cd composition. In addition, the electrical measurements were determined by using a standard DC four-point probe technique. The resistivity increases linearly and the electrical conductivity decreases exponentially with increasing temperature. The resistivity and electrical conductivity are independent of composition of Cd and Zn. Also, the temperature coefficient of Cd-Zn alloys has been determined, which is independent of composition of Cd and Zn. Finally, Lorenz number has been calculated using the thermal and electrical conductivity values at 373 and 533 K. The results satisfy the Wiedemann-Franz (WF) relation at T 373 K), the WF relation could not hold and the phonon component contribution of thermal conductivity dominates the thermal conduction

  13. Double anisotropic electrically conductive flexible Janus-typed membranes.

    Science.gov (United States)

    Li, Xiaobing; Ma, Qianli; Tian, Jiao; Xi, Xue; Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Xinlu; Wang, Jinxian; Liu, Guixia

    2017-12-07

    Novel type III anisotropic conductive films (ACFs), namely flexible Janus-typed membranes, were proposed, designed and fabricated for the first time. Flexible Janus-typed membranes composed of ordered Janus nanobelts were constructed by electrospinning, which simultaneously possess fluorescence and double electrically conductive anisotropy. For the fabrication of the Janus-typed membrane, Janus nanobelts comprising a conductive side and an insulative-fluorescent side were primarily fabricated, and then the Janus nanobelts are arranged into parallel arrays using an aluminum rotary drum as the collector to obtain a single anisotropically conductive film. Subsequently, a secondary electrospinning process was applied to the as-prepared single anisotropically conductive films to acquire the final Janus-typed membrane. For this Janus-typed membrane, namely its left-to-right structure, anisotropic electrical conduction synchronously exists on both sides, and furthermore, the two electrically conductive directions are perpendicular. By modulating the amount of Eu(BA) 3 phen complex and conducting polyaniline (PANI), the characteristics and intensity of the fluorescence-electricity dual-function in the membrane can be tuned. The high integration of this peculiar Janus-typed membrane with simultaneous double electrically conductive anisotropy-fluorescent dual-functionality is successfully realized in this study. This design philosophy and preparative technique will provide support for the design and construction of new types of special nanostructures with multi-functionality.

  14. Ground electrical conductivity for medium wave activities over Nigeria

    African Journals Online (AJOL)

    Ground electrical properties remain a useful tool for most applications in engineering and communication, therefore, reliability and precision is highly required in their determination. Ground electrical conductivity as a function of signal frequency has been determined at Ilorin during the dry and the wet seasons. The study ...

  15. Electrical Resistivity Survey For Conductive Soils At Gas Turbine ...

    African Journals Online (AJOL)

    Ten (10) vertical electrical soundings (VES) using Schlumberger configuration were carried out to delineate subsurface conductive soils for the design of earthling grid for electrical materials installation at the Gas Turbine Station, Ajaokuta, SW Nigeria. Interpretation of the resistivity data revealed three major geoelectric ...

  16. Electrical Conductivity of CUXS Thin Film Deposited by Chemical ...

    African Journals Online (AJOL)

    Thin films of CuxS have successfully been deposited on glass substrates using the Chemical Bath Deposition (CBD) technique. The films were then investigated for their electrical properties. The results showed that the electrical conductivities of the CuxS films with different molarities (n) of thiourea (Tu), determined using ...

  17. Studies on electrical conductivity of poly phenylene vinylene

    International Nuclear Information System (INIS)

    Khattab, Asaad F.; Ahmad, Saddam M.

    2009-01-01

    Four Pp polymers have been synthesized through Wit ting reaction, 1 poly(p-phenylene vinylene), 2 = poly(p phenylene vinylene-co-m-phenylene vinylene), 3 = poly(p-phenylene vinylene-co-o-phenylene vinylene) and 4 poly(p-phenylene-1,5-hexadiene). Electrical conductivity measurements show that the conductivity of polymer 3 is higher than that of polymers 1 and 2. The dihedral angle measurements indicates that the irregularity of polymer chains is the main reason for this fact. The interruption of chain conjugation by aliphatic segments (polymer 4) will increase the conductivity by increasing the chain mobility.The electrical conductivity of the polymers is increased by doping with iodine and by raising the temperature. The effect of annealing with different temperatures on conductivity was studied; the results show that structural conformation of polymeric chain is the main factor affecting electrical conductivity. (author)

  18. D.C. electrical conductivity measurements on ADP single crystals ...

    Indian Academy of Sciences (India)

    Unknown

    Impurity added ADP crystals; density; electrical conductivity measurements. 1. Introduction ... determined by the intrinsic defects caused by thermal fluctuations in the ... beaker (corning glass vessel) and allowed to equilibrate at the desired ...

  19. Correlation of electrical conductivity and photoluminescence in nanoporous silicon

    International Nuclear Information System (INIS)

    Bouaicha, M.; Khardani, M.; Bessais, B.

    2006-01-01

    The effective electrical conductivity of p type porous silicon is determined both theoretically and experimentally for different porosities ranging from 30% to 80%. In this work, Effective Medium Approximation (EMA) model was used as a theoretical support. The porous silicon samples were prepared by the electrochemical etching method for different values of the anodic current. The porous material is assumed to be formed of three phases; vacuum, oxide and Si nanocrystallites. The analytical expression of the electrical conductivity of the Si nanocrystallites was established using the quantum confinement theory. This enables us to correlate the electrical conductivity of a PS layer, to the peak energy of its photoluminescence (PL) spectrum. A perfect agreement between the theoretical and the experimental electrical conductivity values was obtained for all prospected PS porosities. The results are discussed as regard to other works

  20. Magnetohydraulic flow through a packed bed of electrically conducting spheres

    International Nuclear Information System (INIS)

    Sanders, T.L.

    1985-01-01

    The flow of an electrically conducting fluid through a packed bed of electrically conducting spheres in the presence of a strong magnetic field constitutes a very complex flow situation due to the constant turning of the fluid in and out of magnetic field lines. The interaction of the orthogonal components of the velocity and magnetic field will induce electric fields that are orthogonal to both and the electric fields in turn can cause currents that interact with the magnetic field to generate forces against the direction of flow. The strengths of these generated forces depend primarily upon the closure paths taken by the induced currents which, in turn, depend upon the relative ratio of the electrical resistance of the solid spheres to that of the fluid. Both experimental and analytical analyses of the slow flow of a eutectic mixture of sodium and potassium (NaK) through packed cylinders containing stainless steel spheres in the presence of a strong transverse magnetic field were completed. A theory of magnetohydraulic flow is developed by analogy with the development of hydraulic radius theories of flow through porous media. An exact regional analysis is successfully applied to an infinite bed of electrically conducting spheres with a conducting or non-conducting constraining wall on one side. The equations derived are solved for many different combinations of flowrate, magnetic field strength, porosity, and electrical resistance ratio

  1. What we can learn from measurements of air electric conductivity in 222Rn-rich atmosphere

    Science.gov (United States)

    Seran, E.; Godefroy, M.; Pili, E.; Michielsen, N.; Bondiguel, S.

    2017-02-01

    Electric conductivity of air is an important characteristic of the electric properties of an atmosphere. Testing instruments to measure electric conductivity ranging from 10-13 to 10-9 S m-1 in natural conditions found in the Earth atmosphere is not an easy task. One possibility is to use stratospheric balloon flights; another (and a simpler one) is to look for terrestrial environments with significant radioactive decay. In this paper we present measurements carried out with different types of conductivity sensors in two 222Rn-rich environments, i.e., in the Roselend underground tunnel (French Alps) and in the Institute of Radioprotection and Nuclear Safety BACCARA (BAnC de CAllibrage du RAdon) chamber. The concept of the conductivity sensor is based on the classical time relaxation method. New elements in our design include isolation of the sensor sensitive part (electrode) from the external electric field and sensor miniaturization. This greatly extends the application domain of the sensor and permits to measure air electric conductivity when the external electric field is high and varies from few tens of V m-1 to up to few tens of kV m-1. This is suitable to propose the instrument for a planetary mission. Two-fold objectives were attained as the outcome of these tests and their analysis. First was directly related to the performances of the conductivity sensors and the efficiency of the conductivity sensor design to shield the external electric field. Second objective aimed at understanding the decay mechanisms of 222Rn and its progeny in atmosphere and the impact of the enclosed space on the efficiency of gas ionization.

  2. Electrical conductivity of (La,Sr)MnO3

    International Nuclear Information System (INIS)

    Nowotny, J.; Rekas, M.; Sorrell, C.C.

    1998-01-01

    Defect disorder model for undoped and Sr-doped LaMnO 3 was derived from non-stoichiometry data reported in literature. This model is checked against the electrical conductivity data. The regimes corresponding to oxygen deficit and oxygen excess will be discussed. A good agreement between the random defect model and experimental data of the electrical conductivity was revealed. Copyright (1998) Australasian Ceramic Society

  3. Software optimization for electrical conductivity imaging in polycrystalline diamond cutters

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, G.; Ludwig, R. [Department of Electrical and Computer Engineering, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA 01609 (United States); Wiggins, J.; Bertagnolli, K. [US Synthetic, 1260 South 1600 West, Orem, UT 84058 (United States)

    2014-02-18

    We previously reported on an electrical conductivity imaging instrument developed for measurements on polycrystalline diamond cutters. These cylindrical cutters for oil and gas drilling feature a thick polycrystalline diamond layer on a tungsten carbide substrate. The instrument uses electrical impedance tomography to profile the conductivity in the diamond table. Conductivity images must be acquired quickly, on the order of 5 sec per cutter, to be useful in the manufacturing process. This paper reports on successful efforts to optimize the conductivity reconstruction routine, porting major portions of it to NVIDIA GPUs, including a custom CUDA kernel for Jacobian computation.

  4. The Electrical Conductivity of Stretched Polyaniline and Polypyrrole Coated Yarns

    Directory of Open Access Journals (Sweden)

    M. Nouri

    2009-12-01

    Full Text Available The nylon and nylon/lycra yarns were coated with electrically conductive polymers such as polyaniline and polypyrrole, via chemical polymerization process. Electrical conductivity of the coated yarns was measured at variousstrain levels using two-point probe technique and their strain sensitivities were studied. The results showed that, electrical conductivity of the coated yarns decreased with an increase in strain level. A sharp decrease in the electrical conductivity of the nylon/lycra coated yarn with the strain level was recorded whereas, a small drop in the electrical conductivity of the nylon coated yarn was observed. Linear relationships were found between the electrical conductivity and length for the nylon and nylon/lycra coated yarns. The polyaniline coated yarns showed higher strain sensitivity compared to polypyrrole coated yarns. Repeatability of the strain sensitivity of the coated yarns was examined and the coated nylon/lycra yarn showed better repeatability compared to that of coated nylon yarn. The coated yarns were proposed as a flexible strain sensor in the field of intelligent materials.

  5. Sintering behavior, ac conductivity and dielectric relaxation of Li1.3Ti1.7Al0.3(PO43 NASICON compound

    Directory of Open Access Journals (Sweden)

    Tasiu Zangina

    Full Text Available The phenomenon of relaxation in dielectric materials is described as one of the powerful tools to determine the behavior and properties of ion transport. The kinetics of ionic species and dipole in solid-state electrolyte are dependent on frequency, temperature, and dielectric relaxation. Li1+xTi2−xAlx(PO43 conducting solid state electrolyte with x = 0.3 was synthesized via conventional solid state technique using the raw materials Li2CO3, TiO2, Al2O3, and NH4H2PO4 as starting materials. TGA/DTG and X-ray diffraction measurements were carried out to study the thermal behavior and phases of the composition. It was observed from the TGA/DTA curves that there is no mass loss above 500 °C. The XRD peaks were observed to start appearing at 500 °C which corresponds to small peaks in TGA. It was also pointed out that at increasing sintering temperatures from 700 °C to 1000 °C the number of phases drastically decreased which is attributed to the complete chemical reaction. Temperature and frequency dependence of dielectric relaxation and electric modulus of the compounds were investigated at temperatures 30–230 °C and at frequencies of 40 kHz–1 MHz. The findings showed that the dielectric relaxation peaks shift to higher temperature as frequency increases and the change in ac conductivity with frequency is in agreement with Jonscher’s power law. Keywords: Sintering behavior, Dielectric permittivity, Universal power law, Electric modulus

  6. Measuring electric conductivity in liquid metals by eddy current method

    International Nuclear Information System (INIS)

    Zhuravlev, S.P.; Ostrovskij, O.I.; Grigoryan, V.A.

    1982-01-01

    Technique permitting to apply the method of vertiginous currents for investigation of electric conductivity of metal melts in the high temperature range is presented. Interferences affecting accuracy of measurements are specified and ways of their removing are pointed out. Scheme of measuring and design of the facility are described. Results of measuring electric resistance of liquid Fe, Co, Ni obtained for the first time by this method are presented. The data obtained agree with the results of measurements conducted by the method of the rotating magnetic field. Difference in absolute values of electric resistance in parallel experiments for each metal does not exceed 4%

  7. Improving electrical conductivity in polycarbonate nanocomposites using highly conductive PEDOT/PSS coated MWCNTs

    KAUST Repository

    Zhou, Jian

    2013-07-10

    We describe a strategy to design highly electrically conductive polycarbonate nanocomposites by using multiwalled carbon nanotubes (MWCNTs) coated with a thin layer of poly(3,4-ethylenedioxythiophene)/ poly(styrenesulfonate), a conductive polymer. We found that this coating method improves the electrical properties of the nanocomposites in two ways. First, the coating becomes the main electrical conductive path. Second, the coating promotes the formation of a percolation network at a low filler concentration (0.3 wt %). To tailor the electrical properties of the conductive polymer coating, we used a polar solvent ethylene glycol, and we can tune the final properties of the nanocomposite by controlling the concentrations of the elementary constituents or the intrinsic properties of the conductive polymer coating. This very flexible technique allows for tailoring the properties of the final product. © 2013 American Chemical Society.

  8. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    Science.gov (United States)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  9. Effect of lanthanum substitution on dielectric relaxation, impedance response, conducting and magnetic properties of strontium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Want, Basharat, E-mail: bawant@kashmiruniversity.ac.in; Bhat, Bilal Hamid; Ahmad, Bhat Zahoor

    2015-04-05

    Highlights: • The substitution of La affects the dielectric and magnetic properties of strontium hexaferrite. • The electric behaviour of the compound follows the Koop’s phenomenological theory. • The impedance study shows the role of grain boundaries to the electric properties of the compound. • The substitution of La to strontium hexaferrite reduces the resistive nature of grain boundaries. - Abstract: Lanthanum strontium hexaferrite Sr{sub 1−x}La{sub x}Fe{sub 12}O{sub 19} (x = 0, 0.08, 0.13 , 0.18) has been successfully synthesized by using citrate-precursor method and characterized by different techniques. The X-ray diffraction results revealed that the sample is crystalline in nature and is of single phase with the space group P63/mmc. The dielectric, conducting and impedance related studies have been carried out as a function of frequency and concentration of lanthanum in the frequency ranges of 20 Hz–3 MHz. Impedance studies were performed in the frequency domain to distinguish between bulk and grain boundary contributions of the material to the overall dielectric response. The electric response of the material was also modeled by an equivalent circuit and different circuit parameters were calculated. Magnetic characterization of the material was also performed and the effect of lanthanum concentration was studied. The hysteresis loop obtained from the magnetometer showed that with the increase of lanthanum concentration, the saturation magnetisation decreases while as coercivity increases.

  10. A percolation approach to study the high electric field effect on electrical conductivity of insulating polymer

    Science.gov (United States)

    Benallou, Amina; Hadri, Baghdad; Martinez-Vega, Juan; El Islam Boukortt, Nour

    2018-04-01

    The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework.

  11. Transport properties of olivine grain boundaries from electrical conductivity experiments

    Science.gov (United States)

    Pommier, Anne; Kohlstedt, David L.; Hansen, Lars N.; Mackwell, Stephen; Tasaka, Miki; Heidelbach, Florian; Leinenweber, Kurt

    2018-05-01

    Grain boundary processes contribute significantly to electronic and ionic transports in materials within Earth's interior. We report a novel experimental study of grain boundary conductivity in highly strained olivine aggregates that demonstrates the importance of misorientation angle between adjacent grains on aggregate transport properties. We performed electrical conductivity measurements of melt-free polycrystalline olivine (Fo90) samples that had been previously deformed at 1200 °C and 0.3 GPa to shear strains up to γ = 7.3. The electrical conductivity and anisotropy were measured at 2.8 GPa over the temperature range 700-1400 °C. We observed that (1) the electrical conductivity of samples with a small grain size (3-6 µm) and strong crystallographic preferred orientation produced by dynamic recrystallization during large-strain shear deformation is a factor of 10 or more larger than that measured on coarse-grained samples, (2) the sample deformed to the highest strain is the most conductive even though it does not have the smallest grain size, and (3) conductivity is up to a factor of 4 larger in the direction of shear than normal to the shear plane. Based on these results combined with electrical conductivity data for coarse-grained, polycrystalline olivine and for single crystals, we propose that the electrical conductivity of our fine-grained samples is dominated by grain boundary paths. In addition, the electrical anisotropy results from preferential alignment of higher-conductivity grain boundaries associated with the development of a strong crystallographic preferred orientation of the grains.

  12. Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

    2017-10-17

    Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

  13. Mechanically stiff, electrically conductive composites of polymers and carbon nanotubes

    Science.gov (United States)

    Worsley, Marcus A.; Kucheyev, Sergei O.; Baumann, Theodore F.; Kuntz, Joshua D.; Satcher, Jr., Joe H.; Hamza, Alex V.

    2015-07-21

    Using SWNT-CA as scaffolds to fabricate stiff, highly conductive polymer (PDMS) composites. The SWNT-CA is immersing in a polymer resin to produce a SWNT-CA infiltrated with a polymer resin. The SWNT-CA infiltrated with a polymer resin is cured to produce the stiff and electrically conductive composite of carbon nanotube aerogel and polymer.

  14. Effect of sodium adsorption ratio and electric conductivity of the ...

    African Journals Online (AJOL)

    Infiltration measurements using a double-ring infiltrometer were conducted on a sandy-loam soil located in Saudi Arabia. The measurements were performed for an undisturbed soil. The effect of sodium adsorption ratio (SAR) and electric conductivity (EC) of the applied water on infiltration rate was examined. The infiltration ...

  15. Improving electrical conductivity in polycarbonate nanocomposites using highly conductive PEDOT/PSS coated MWCNTs

    KAUST Repository

    Zhou, Jian; Lubineau, Gilles

    2013-01-01

    concentration (0.3 wt %). To tailor the electrical properties of the conductive polymer coating, we used a polar solvent ethylene glycol, and we can tune the final properties of the nanocomposite by controlling the concentrations of the elementary constituents

  16. A nonconjugated radical polymer glass with high electrical conductivity

    Science.gov (United States)

    Joo, Yongho; Agarkar, Varad; Sung, Seung Hyun; Savoie, Brett M.; Boudouris, Bryan W.

    2018-03-01

    Solid-state conducting polymers usually have highly conjugated macromolecular backbones and require intentional doping in order to achieve high electrical conductivities. Conversely, single-component, charge-neutral macromolecules could be synthetically simpler and have improved processibility and ambient stability. We show that poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl), a nonconjugated radical polymer with a subambient glass transition temperature, underwent rapid solid-state charge transfer reactions and had an electrical conductivity of up to 28 siemens per meter over channel lengths up to 0.6 micrometers. The charge transport through the radical polymer film was enabled with thermal annealing at 80°C, which allowed for the formation of a percolating network of open-shell sites in electronic communication with one another. The electrical conductivity was not enhanced by intentional doping, and thin films of this material showed high optical transparency.

  17. A coupled magneto-thermo-elastic problem in a perfectly conducting elastic half-space with thermal relaxation

    Directory of Open Access Journals (Sweden)

    S. K. Roy-Choudhuri

    1990-01-01

    Full Text Available In the present paper we consider the magneto-thermo-elastic wave produced by a thermal shock in a perfectly conducting elastic half-space. Here the Lord-Shulman theory of thermoelasticity [1] is used to account for the interaction between the elastic and thermal fields. The solution obtained in analytical form reduces to those of Kaliski and Nowacki [2] when the coupling between the temperature and strain fields and the relaxation time are neglected. The results also agree with those of Massalas and DaLamangas [3] in absence of the thermal relaxation time.

  18. Fast Lagrangian relaxation for constrained generation scheduling in a centralized electricity market

    International Nuclear Information System (INIS)

    Ongsakul, Weerakorn; Petcharaks, Nit

    2008-01-01

    This paper proposes a fast Lagrangian relaxation (FLR) for constrained generation scheduling (CGS) problem in a centralized electricity market. FLR minimizes the consumer payment rather than the total supply cost subject to the power balance, spinning reserve, transmission line, and generator operating constraints. FLR algorithm is improved by new initialization of Lagrangian multipliers and adaptive adjustment of Lagrangian multipliers. The adaptive subgradient method using high quality initial feasible multipliers requires much less number of iterations to converge, leading to a faster computational time. If congestion exists, the alleviating congestion index is proposed for congestion management. Finally, the unit decommitment is performed to prevent excessive spinning reserve. The FLR for CGS is tested on the 4 unit and the IEEE 24 bus reliability test systems. The proposed uniform electricity price results in a lower consumer payment than system marginal price based on uniformly fixed cost amortized allocation, non-uniform price, and electricity price incorporating side payment, leading to a lower electricity price. In addition, observations on objective functions, pricing scheme comparison and interpretation of Lagrangian multipliers are provided. (author)

  19. High temperature heat capacities and electrical conductivities of boron carbides

    International Nuclear Information System (INIS)

    Matsui, Tsuneo; Arita, Yuri; Naito, Keiji; Imai, Hisashi

    1991-01-01

    The heat capacities and the electrical conductivities of B x C(x=3, 4, 5) were measured by means of direct heating pulse calorimetry in the temperature range from 300 to 1500 K. The heat capacities of B x C increased with increasing x value. This increase in the heat capacity is probably related to the change of the lattice vibration mode originated from the reduction of the stiffness of the intericosahedral chain accompanied with a change from C-B-C to C-B-B chains. A linear relationship between the logarithm of σT (σ is the electrical conductivity and T is the absolute temperature) of B x C and the reciprocal temperature was observed, indicating the presence of small polaron hopping as the predominant conduction mechanism. The electrical conductivity of B x C also increased with increasing x value (from 4 to 5) due to an increase of the polaron hopping of holes between carbon atoms at geometrically nonequivalent sites, since these nonequivalent sites of carbon atoms were considered to increase in either B 11 C icosahedra or in icosahedral chains with increasing x. The electrical conductivity of B 3 C was higher than that of B 4 C, which is probably due to the precipitation of high-conducting carbon. The thermal conductivity and the thermodynamic quantities of B 4 C were also determined precisely from the heat capacity value. (orig.)

  20. Electrical and Thermal Conductivity and Conduction Mechanism of Ge2Sb2Te5 Alloy

    Science.gov (United States)

    Lan, Rui; Endo, Rie; Kuwahara, Masashi; Kobayashi, Yoshinao; Susa, Masahiro

    2017-11-01

    Ge2Sb2Te5 alloy has drawn much attention due to its application in phase-change random-access memory and potential as a thermoelectric material. Electrical and thermal conductivity are important material properties in both applications. The aim of this work is to investigate the temperature dependence of the electrical and thermal conductivity of Ge2Sb2Te5 alloy and discuss the thermal conduction mechanism. The electrical resistivity and thermal conductivity of Ge2Sb2Te5 alloy were measured from room temperature to 823 K by four-terminal and hot-strip method, respectively. With increasing temperature, the electrical resistivity increased while the thermal conductivity first decreased up to about 600 K then increased. The electronic component of the thermal conductivity was calculated from the Wiedemann-Franz law using the resistivity results. At room temperature, Ge2Sb2Te5 alloy has large electronic thermal conductivity and low lattice thermal conductivity. Bipolar diffusion contributes more to the thermal conductivity with increasing temperature. The special crystallographic structure of Ge2Sb2Te5 alloy accounts for the thermal conduction mechanism.

  1. Electrical and Thermal Conductivity and Conduction Mechanism of Ge2Sb2Te5 Alloy

    Science.gov (United States)

    Lan, Rui; Endo, Rie; Kuwahara, Masashi; Kobayashi, Yoshinao; Susa, Masahiro

    2018-06-01

    Ge2Sb2Te5 alloy has drawn much attention due to its application in phase-change random-access memory and potential as a thermoelectric material. Electrical and thermal conductivity are important material properties in both applications. The aim of this work is to investigate the temperature dependence of the electrical and thermal conductivity of Ge2Sb2Te5 alloy and discuss the thermal conduction mechanism. The electrical resistivity and thermal conductivity of Ge2Sb2Te5 alloy were measured from room temperature to 823 K by four-terminal and hot-strip method, respectively. With increasing temperature, the electrical resistivity increased while the thermal conductivity first decreased up to about 600 K then increased. The electronic component of the thermal conductivity was calculated from the Wiedemann-Franz law using the resistivity results. At room temperature, Ge2Sb2Te5 alloy has large electronic thermal conductivity and low lattice thermal conductivity. Bipolar diffusion contributes more to the thermal conductivity with increasing temperature. The special crystallographic structure of Ge2Sb2Te5 alloy accounts for the thermal conduction mechanism.

  2. Optical and Electrical Characteristics of Silver Ion Conducting Nanocomposite Solid Polymer Electrolytes Based on Chitosan

    Science.gov (United States)

    Aziz, Shujahadeen B.; Rasheed, Mariwan A.; Abidin, Zul H. Z.

    2017-10-01

    Optical and electrical properties of nanocomposite solid polymer electrolytes based on chitosan have been investigated. Incorporation of alumina nanoparticles into the chitosan:silver triflate (AgTf) system broadened the surface plasmon resonance peaks of the silver nanoparticles and shifted the absorption edge to lower photon energy. A clear decrease of the optical bandgap in nanocomposite samples containing alumina nanoparticles was observed. The variation of the direct-current (DC) conductivity and dielectric constant followed the same trend with alumina concentration. The DC conductivity increased by two orders of magnitude, which can be attributed to hindrance of silver ion reduction. Transmission electron microscopy was used to interpret the space-charge and blocking effects of alumina nanoparticles on the DC conductivity and dielectric constant. The ion conduction mechanism was interpreted based on the dependences of the electrical and dielectric parameters. The dependence of the DC conductivity on the dielectric constant is explained empirically. Relaxation processes associated with conductivity and viscoelasticity were distinguished based on the incomplete semicircular arcs in plots of the real and imaginary parts of the electric modulus.

  3. Fabrication of highly conductive carbon nanotube fibers for electrical application

    International Nuclear Information System (INIS)

    Guo, Fengmei; Li, Can; Wei, Jinquan; Xu, Ruiqiao; Zhang, Zelin; Cui, Xian; Wang, Kunlin; Wu, Dehai

    2015-01-01

    Carbon nanotubes (CNTs) have great potential for use as electrical wires because of their outstanding electrical and mechanical properties. Here, we fabricate lightweight CNT fibers with electrical conductivity as high as that of stainless steel from macroscopic CNT films by drawing them through diamond wire-drawing dies. The entangled CNT bundles are straightened by suffering tension, which improves the alignment of the fibers. The loose fibers are squeezed by the diamond wire-drawing dies, which reduces the intertube space and contact resistance. The CNT fibers prepared by drawing have an electrical conductivity as high as 1.6 × 10 6 s m −1 . The fibers are very stable when kept in the air and under cyclic tensile test. A prototype of CNT motor is demonstrated by replacing the copper wires with the CNT fibers. (paper)

  4. Method and device for electromagnetic pumping by conduction of liquid metals having low electrical conductivity

    International Nuclear Information System (INIS)

    Le Frere, J.P.

    1976-01-01

    The invention is related to a method for pumping of liquid metals having a low electrical conductivity. To lower the resistance of the conductive spire containing liquid metal to be pumped, a tape formed by a conductive metal such as copper or nickel is inserted in that spire. The tape is interrupted at the level of the air gap of the main magnetic circuit at least when the conductive spire passes through that air gap

  5. Conductance relaxation in GeBiTe: Slow thermalization in an open quantum system

    Science.gov (United States)

    Ovadyahu, Z.

    2018-02-01

    This work describes the microstructure and transport properties of GeBixTey films with emphasis on their out-of-equilibrium behavior. Persistent-photoconductivity (PPC), previously studied in the phase-change compound GeSbxTey , is also quite prominent in this system. Much weaker PPC response is observed in the pure GeTe compound and when alloying GeTe with either In or Mn. Films made from these compounds share the same crystallographic structure, the same p -type conductivity, a similar compositional disorder extending over mesoscopic scales, and similar mosaic morphology. The enhanced photoconductive response exhibited by the Sb and Bi alloys may therefore be related to their common chemistry. Persistent photoconductivity is observable in GeBixTey films at the entire range of sheet resistances studied in this work (≈103Ω to ≈55 M Ω ). The excess conductance produced by a brief exposure to infrared illumination decays with time as a stretched exponential (Kohlrausch law). Intrinsic electron-glass effects, on the other hand, are observable in thin films of GeBixTey only for samples that are strongly localized just like it was noted with the seven electron glasses previously studied. These include a memory dip which is the defining attribute of the phenomenon. The memory dip in GeBixTey is the widest amongst the germanium-telluride alloys studied to date consistent with the high carrier concentration N ≥1021cm-3 of this compound. The thermalization process exhibited in either the PPC state or in the electron-glass regime is sluggish but the temporal law of the relaxation from the out-of-equilibrium state is distinctly different. Coexistence of the two phenomena give rise to some nontrivial effects, in particular, the visibility of the memory dip is enhanced in the PPC state. The relation between this effect and the dependence of the memory-effect magnitude on the ratio between the interparticle interaction and quench disorder is discussed.

  6. Electric Circuit Model Analogy for Equilibrium Lattice Relaxation in Semiconductor Heterostructures

    Science.gov (United States)

    Kujofsa, Tedi; Ayers, John E.

    2018-01-01

    The design and analysis of semiconductor strained-layer device structures require an understanding of the equilibrium profiles of strain and dislocations associated with mismatched epitaxy. Although it has been shown that the equilibrium configuration for a general semiconductor strained-layer structure may be found numerically by energy minimization using an appropriate partitioning of the structure into sublayers, such an approach is computationally intense and non-intuitive. We have therefore developed a simple electric circuit model approach for the equilibrium analysis of these structures. In it, each sublayer of an epitaxial stack may be represented by an analogous circuit configuration involving an independent current source, a resistor, an independent voltage source, and an ideal diode. A multilayered structure may be built up by the connection of the appropriate number of these building blocks, and the node voltages in the analogous electric circuit correspond to the equilibrium strains in the original epitaxial structure. This enables analysis using widely accessible circuit simulators, and an intuitive understanding of electric circuits can easily be extended to the relaxation of strained-layer structures. Furthermore, the electrical circuit model may be extended to continuously-graded epitaxial layers by considering the limit as the individual sublayer thicknesses are diminished to zero. In this paper, we describe the mathematical foundation of the electrical circuit model, demonstrate its application to several representative structures involving In x Ga1- x As strained layers on GaAs (001) substrates, and develop its extension to continuously-graded layers. This extension allows the development of analytical expressions for the strain, misfit dislocation density, critical layer thickness and widths of misfit dislocation free zones for a continuously-graded layer having an arbitrary compositional profile. It is similar to the transition from circuit

  7. Synthesis and characterization of electrical conducting nanoporous carbon structures

    International Nuclear Information System (INIS)

    El Mir, L.; Kraiem, S.; Bengagi, M.; Elaloui, E.; Ouederni, A.; Alaya, S.

    2007-01-01

    Nanoporous organic xerogel compounds were prepared by sol-gel method from pyrogallol-formaldehyde (PF) mixtures in water using perchloric acid as catalyst. The preparation conditions of electrical conducting carbon (ECC) structures were explored by changing the pyrolysis temperature. The effect of this preparation parameters on the structural and electrical properties of the obtained ECCs were studied, respectively, by thermogravimetric analysis (TGA), nitrogen adsorption isotherms, IR spectroscopy and electrical conductivity measurements. The analysis of the obtained results revealed that, the polymeric insulating phase was transformed progressively with pyrolysis temperature into carbon conducting phase; this means the formation of long continuous conducting path for charge carriers when the carbon microparticles inside the structure agglomerated with thermal treatment and the samples exhibited tangible percolation behaviour where the percolation threshold can be determined by pyrolysis temperature. The temperature-dependent conductivity and the I(V) characteristics of the obtained ECC structures show a non-ohmic behaviour. The results obtained from TGA and differential thermal analyser (DTA) thermograms, scanning electron microscope (SEM) and transmission electron microscope (TEM) micrographs, IR spectroscopy and X-ray diffraction revealed that, the obtained ECC structures consist of amorphous and nanoporous electrical conducting carbon materials

  8. Adaptation of electrical conductivity test for Moringa oleifera seeds

    Directory of Open Access Journals (Sweden)

    Maria Luiza de Souza Medeiros

    2017-09-01

    Full Text Available This study aimed to adapt and test the efficiency of electrical conductivity methodology test in quality evaluation of Moringa oleifera Lam seeds. For physiological characterization four seed sets were evaluated by tests of germination, seedlings emergency, speed of emergency index, emergency first count, seedlings length and dry mass and cold test. The electrical conductivity test was carried out at 25 °C for 4, 8, 12, 16 and 24 h of immersion in 75 or 125 mL of distilled water using 25 or 50 seeds. A completely randomized design was used. The best results were obtained when using 50 seeds immersed in 75 mL or 125 mL of distilled water for 4 h. The electrical conductivity test adapted to moringa seeds was efficient in ranking sets of different vigor levels. The test may be efficiently used for physiological quality evaluation of moringa seeds.

  9. Computational analysis of electrical conduction in hybrid nanomaterials with embedded non-penetrating conductive particles

    Science.gov (United States)

    Cai, Jizhe; Naraghi, Mohammad

    2016-08-01

    In this work, a comprehensive multi-resolution two-dimensional (2D) resistor network model is proposed to analyze the electrical conductivity of hybrid nanomaterials made of insulating matrix with conductive particles such as CNT reinforced nanocomposites and thick film resistors. Unlike existing approaches, our model takes into account the impenetrability of the particles and their random placement within the matrix. Moreover, our model presents a detailed description of intra-particle conductivity via finite element analysis, which to the authors’ best knowledge has not been addressed before. The inter-particle conductivity is assumed to be primarily due to electron tunneling. The model is then used to predict the electrical conductivity of electrospun carbon nanofibers as a function of microstructural parameters such as turbostratic domain alignment and aspect ratio. To simulate the microstructure of single CNF, randomly positioned nucleation sites were seeded and grown as turbostratic particles with anisotropic growth rates. Particle growth was in steps and growth of each particle in each direction was stopped upon contact with other particles. The study points to the significant contribution of both intra-particle and inter-particle conductivity to the overall conductivity of hybrid composites. Influence of particle alignment and anisotropic growth rate ratio on electrical conductivity is also discussed. The results show that partial alignment in contrast to complete alignment can result in maximum electrical conductivity of whole CNF. High degrees of alignment can adversely affect conductivity by lowering the probability of the formation of a conductive path. The results demonstrate approaches to enhance electrical conductivity of hybrid materials through controlling their microstructure which is applicable not only to carbon nanofibers, but also many other types of hybrid composites such as thick film resistors.

  10. Electrical conductivity of chromate conversion coating on electrodeposited zinc

    International Nuclear Information System (INIS)

    Tencer, Michal

    2006-01-01

    For certain applications of galvanized steel protected with conversion coatings it is important that the surface is electrically conductive. This is especially important with mating surfaces for electromagnetic compatibility. This paper addresses electrical conductivity of chromate conversion coatings. A cross-matrix study using different zinc plating techniques by different labs showed that the main deciding factor is the type of zinc-plating bath used rather than the subsequent chromating process. Thus, chromated zinc plate electrodeposited from cyanide baths is non-conductive while that from alkaline (non-cyanide) and acid baths is conductive, even though the plate from all the bath types is conductive before conversion coating. The results correlate well with the microscopic structure of the surfaces as observed with scanning electron microscopy (SEM) and could be further corroborated and rationalized using EDX and Auger spectroscopies

  11. Electrical conduction along dislocations in plastically deformed GaN

    Energy Technology Data Exchange (ETDEWEB)

    Kamimura, Y; Yokoyama, T; Oiwa, H; Edagawa, K [Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Yonenaga, I, E-mail: yasushi@iis.u-tokyo.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan)

    2009-07-15

    Electrical conduction along dislocations in plastically deformed n-GaN single crystals has been investigated by scanning spread resistance microscopy (SSRM). In the SSRM images, many conductive spots have been observed, which correspond to electrical conduction along the dislocations introduced by deformation. Here, the introduced dislocations are b=(a/3)<1overline 210> edge dislocations parallel to the [0001] direction. The current values at the spots normalized to the background current value are larger than 100. Previous works have shown that grown-in edge dislocations in GaN are nonconductive. The high conductivity of the deformation-introduced edge dislocations in the present work suggests that the conductivity depends sensitively on the dislocation core structure.

  12. Application of the Maxwell-Wagner-Hanai effective medium theory to the analysis of the interfacial polarization relaxations in conducting composite films

    International Nuclear Information System (INIS)

    Adohi, B J-P; Bouanga, C Vanga; Fatyeyeva, K; Tabellout, M

    2009-01-01

    A new approach to explain the interfacial polarization phenomenon in conducting composite films is proposed. HCl-doped poly(ethylene terephthalate) (PET) and polyamide-6 (PA-6) matrices with embedded polyaniline (PANI) particles as filler were investigated and analysed, combining dielectric spectroscopy and AFM electrical images with the effective medium theory analysis. Up to three relaxation peaks attributed to the interfacial polarization phenomena were detected in the studied frequency range (0.1 Hz-1 MHz). The AFM electrical images revealed that the doped PA-6/PANI composite can be modelled as a single-type particle medium and the PET/PANI one as a two-type particle medium. A simple dielectric loss expression was derived from the Maxwell-Wagner-Hanai mixture equation and was applied to the experimental data to identify the interfaces involved in each of the relaxation peaks. The parameter values (permittivity, conductivity, volume fraction of the PANI particles) were found to agree well with the measured one, hence validating the models.

  13. The structural and electrical characterisation of SiGe heterostructures deposited on strain relaxed virtual substrates

    International Nuclear Information System (INIS)

    Hammond, R.

    1998-09-01

    The influence of lateral dimensions on the relaxation mechanism and the resulting effect on the surface topography of limited-area, linearly graded Si 1-x Ge x virtual substrates has been investigated for the first time. A dramatic change in the relaxation mechanism of such buffer layers has been observed for depositions on Si mesa pillars of lateral dimensions of 10μm and below. For such depositions, misfit dislocations are able to extend, unhindered, and terminate at the edges of the growth zone. In this manner, orthogonal misfit dislocation interactions are avoided, yielding a surface free of the problematic surface cross-hatch roughening. However, as the lateral dimension of the growth zone is increased to 20μm, orthogonal misfit interactions occur and relaxation is dominated by the Modified Frank-Read (MFR) multiplication mechanism. The resulting surface morphology shows a pronounced surface cross-hatch roughening. It is proposed that such cross-hatch roughening is a direct consequence of the cooperative stress fields associated with the MFR mechanism. It is postulated that the method of limited-area, linearly graded buffer layers provides a unique opportunity, by which 'ideal' virtual substrates, free of surface cross-hatch and threading dislocations, may be produced to any Ge content. In addition, a unique method by which the electrical performance of low temperature, strained layer depositions may be optimised is discussed. The method relies on the elimination of as-grown lattice imperfections via a post growth thermal anneal treatment. A 25-fold increase in low temperature hole mobility of a Si 0.5 Ge 0.5 /Si 0.7 Ge 0.3 heterostructure has been demonstrated using a 30minute, 750 deg C in-situ, post growth anneal. (author)

  14. Measurement of total dissolved solids using electrical conductivity

    International Nuclear Information System (INIS)

    Ray, Vinod K.; Jat, J.R.; Reddy, G.B.; Balaji Rao, Y.; Phani Babu, C.; Kalyanakrishnan, G.

    2017-01-01

    Total dissolved solids (TDS) is an important parameter for the disposal of effluents generated during processing of different raw materials like Magnesium Di-uranate (MDU), Heat Treated Uranium Peroxide (HTUP), Sodium Di-uranate (SDU) in Uranium Extraction plant and Washed and Dried Frit (WDF) in Zirconium Extraction Plant. The present paper describes the use of electrical conductivity for determination of TDS. As electrical conductivity is matrix dependent property, matrix matched standards were prepared for determination of TDS in ammonium nitrate solution (AN) and mixture of ammonium nitrate and ammonium sulphate (AN/AS) and results were found to be in good agreement when compared with evaporation method. (author)

  15. Challenges associated with nerve conduction block using kilohertz electrical stimulation

    Science.gov (United States)

    Patel, Yogi A.; Butera, Robert J.

    2018-06-01

    Neuromodulation therapies, which electrically stimulate parts of the nervous system, have traditionally attempted to activate neurons or axons to restore function or alleviate disease symptoms. In stark contrast to this approach is inhibiting neural activity to relieve disease symptoms and/or restore homeostasis. One potential approach is kilohertz electrical stimulation (KES) of peripheral nerves—which enables a rapid, reversible, and localized block of conduction. This review highlights the existing scientific and clinical utility of KES and discusses the technical and physiological challenges that must be addressed for successful translation of KES nerve conduction block therapies.

  16. Relaxations in Ba{sub 2}BiTaO{sub 6} ceramics investigated by impedance and electric modulus spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Joao Elias Figuereido Soares [Departamento de Fisica - CCET, Universidade Federal do Maranhao, Campus do Bacanga, 65085-580, Sao Luis -MA (Brazil); Paschoal, Carlos William de Araujo, E-mail: paschoal@ufma.br [Departamento de Fisica - CCET, Universidade Federal do Maranhao, Campus do Bacanga, 65085-580, Sao Luis -MA (Brazil); Silva, Eder Nascimento [Departamento de Fisica - CCET, Universidade Federal do Maranhao, Campus do Bacanga, 65085-580, Sao Luis -MA (Brazil); Mince, Kathryn A.; Lufaso, Michael W. [Department of Chemistry, University of North Florida, 1 UNF Drive, Jacksonville, FL 32224 (United States)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We have confirmed that the relaxation observed in Ba{sub 2}BiTaO{sub 6} is due to the conduction mechanism. Black-Right-Pointing-Pointer The conduction mechanism is the oxygen vacancies hopping. Black-Right-Pointing-Pointer We have explained because the activation energy for the Ba{sub 2}BiTaO{sub 6} is lower than observed for Ba{sub 2}BiSbO{sub 6} with basis in zero-point energy of both materials. Black-Right-Pointing-Pointer We have showed that a minor secondary phase is a minor secondary phase, which is common when the BBTO is obtained by ceramic method under air, does not change significantly the electrical properties of BBTO. -- Abstract: Impedance spectroscopy analysis of the dielectric properties of a Ba{sub 2}BiTaO{sub 6} ceramic was performed in the temperature range from room temperature to 500 K. The sample was prepared using conventional solid state synthesis under air and the X-ray diffraction shows the presence of Ba{sub 5}Ta{sub 4}O{sub 15} as a minor secondary phase (0.09%). The impedance data clearly show contributions of the grain and grain boundary. The results indicate that the conduction in Ba{sub 2}BiTaO{sub 6} is due to hopping of oxygen vacancies and that the impurities not influence the conduction mechanism.

  17. Direct numerical simulation of MHD flow with electrically conducting wall

    International Nuclear Information System (INIS)

    Satake, S.; Kunugi, T.; Naito, N.; Sagara, A.

    2006-01-01

    The 2D vortex problem and 3D turbulent channel flow are treated numerically to assess the effect of electrically conducting walls on turbulent MHD flow. As a first approximation, the twin vortex pair is considered as a model of a turbulent eddy near the wall. As the eddy approaches and collides with the wall, a high value electrical potential is induced inside the wall. The Lorentz force, associated with the potential distribution, reduces the velocity gradient in the near-wall region. When considering a fully developed turbulent channel flow, a high electrical conductivity wall was chosen to emphasize the effect of electromagnetic coupling between the wall and the flow. The analysis was performed using DNS. The results are compared with a non-MHD flow and MHD flow in the insulated channel. The mean velocity within the logarithmic region in the case of the electrically conducting wall is slightly higher than that in the non-conducting wall case. Thus, the drag is smaller compared to that in the non-conducting wall case due to a reduction of the Reynolds stress in the near wall region through the Lorentz force. This mechanism is explained via reduction of the production term in the Reynolds shear stress budget

  18. Enhanced electrical conductivity in graphene and boron nitride nanoribbons in large electric fields

    Science.gov (United States)

    Chegel, Raad

    2018-02-01

    Based on data of density function theory (DFT) as the input of tight binding model, the electrical conductivity (σ(T)) of graphene nanoribbos (GNRs) and Boron Nitride nanoribbos (BNNRs) under external electric fields with different wide are studied using the Green's function method. The BNNRs are wide band gap semiconductor and they are turned into metal depending on their electric field strength. The σ(T) shows increasing in low temperature region and after reaching the maximum value, it will decrease in high temperature region. In lower temperature ranges, the electrical conductivity of the GNRs is greater than that of the BNNRs. In a low temperature region, the σ(T) of GNRs increases linearly with temperature unlike the BNNRs. The electrical conductivity are strongly dependent on the electric field strength.

  19. Overall conductivity and NCL-type relaxation behavior in nanocrystalline sodium peroxide Na{sub 2}O{sub 2}—Consequences for Na-oxygen batteries

    Energy Technology Data Exchange (ETDEWEB)

    Dunst, Andreas; Sternad, Michael; Wilkening, Martin, E-mail: wilkening@tugraz.at

    2016-09-15

    Highlights: • Na{sub 2}O{sub 2} turned out to be a poor electrical conductor. • Total conductivity of nanocrystalline Na{sub 2}O{sub 2} measured slightly above room temperature is in the order of 10{sup −15} S cm{sup −1}. • Activation energies of micro- and nanocrystalline Na{sub 2}O{sub 2} are in the order of 1 eV. • At low temperatures nearly constant loss behavior showed up pointing to locally restricted electrical relaxation processes. - Abstract: Metal air batteries are considered as promising candidates for room-temperature batteries with high-energy densities. On discharge, atmospheric oxygen is reduced at the positive electrode which, in the ideal case, forms the discharge products in a reversible cell reaction. In Na-O{sub 2} batteries upon discharge either sodium peroxide (Na{sub 2}O{sub 2}) or sodium superoxide (NaO{sub 2}) is reported to be formed. So far, the charge carrier transport remains relatively unexplored but is expected to crucially determine the efficiency of such energy storage systems. Na{sub 2}O{sub 2} is predicted to be an electrical insulator wherein the transport presumably is determined by very slow hopping processes. Understanding the basic fundamental properties of the overall charge carrier transport, including also nanostructured forms of Na{sub 2}O{sub 2}, is key to developing high-energy metal oxygen batteries. The present study answers the question how overall, i.e., total, conductivity changes when going from microcrystalline to nanocrystalline, defect-rich Na{sub 2}O{sub 2}. Nanocrystalline Na{sub 2}O{sub 2} was prepared via a top-down approach, viz by high-energy ball milling. Milling does not only shrink the average crystallite diameter but also introduces a large amount of defects which are anticipated to influence total conductivity. It turned out that even after vigorous mechanical treatment the conductivity of the sample is only increased by ca. one order of magnitude. The activation energy remains almost

  20. Anisotropic modelling of the electrical conductivity of fractured bedrock

    International Nuclear Information System (INIS)

    Flykt, M.J.; Sihvola, A.H.; Eloranta, E.H.

    1995-01-01

    The electromagnetic characterization of fractured bedrock is of importance when studying the final disposal of nuclear waste. The different types of discontinuities at all scales in rocks can be viewed as an inhomogeneity. In some cases there are reasons to assume the influence of the discontinuities on electrical conductivity is anisotropic in character. The effort has been made to use electromagnetic mixing rules in the definition of an equivalent homogeneous anisotropic conductivity tensor for such fractured rock mass. (author) (16 refs., 6 figs.)

  1. Electrical conductivity measurements in shock compressed liquid nitrogen

    International Nuclear Information System (INIS)

    Hamilton, D.C.; Mitchell, A.C.; Nellis, W.J.

    1985-06-01

    The electrical conductivity of shock compressed liquid nitrogen was measured in the pressure range 20 to 50 GPa using a two-stage light-gas gun. The conductivities covered a range 4 x 10 -2 to 1 x 10 2 ohm -1 cm -1 . The data are discussed in terms of a liquid semiconductor model below the onset of the dissociative phase transition at 30 GPa. 15 refs., 1 fig

  2. Enhancement of electrical conductivity of ion-implanted polymer films

    International Nuclear Information System (INIS)

    Brock, S.

    1985-01-01

    The electrical conductivity of ion-implanted films of Nylon 66, Polypropylene (PP), Poly(tetrafluoroethylene) (Teflon) and mainly Poly (ethylene terephthalate) (PET) was determined by DC measurements at voltages up to 4500 V and compared with the corresponding values of pristine films. Measurements were made at 21 0 C +/- 1 0 C and 65 +/- 2% RH. The electrical conductivity of PET films implanted with F + , Ar + , or As + ions at energies of 50 keV increases by seven orders of magnitude as the fluence increases from 1 x 10 18 to 1 x 10 20 ions/m 2 . The conductivity of films implanted with As + was approximately one order greater than those implanted with Ar + , which in turn was approximately one-half order greater than those implanted with F + . The conductivity of the most conductive film ∼1 S/m) was almost 14 orders of magnitude greater than the pristine PET film. Except for the three PET samples implanted at fluences near 1 x 10 20 ions/m 2 with F + , Ar + , and As + ions, all implanted films were ohmic up to an electric field strength of 600 kV/m. The temperature dependence of the conductivity of the three PET films implanted near a fluence of 1 x 10 20 ions/m 2 was measured over the range of 80 K < T < 300 K

  3. Evaluation of Electrical and Thermal Conductivity of Polymeric ...

    African Journals Online (AJOL)

    PROF HORSFALL

    ABSTRACT: This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with ...

  4. Electrical conductivity and pH of groundwater: important exploratory ...

    African Journals Online (AJOL)

    Electrical conductivity and pH of groundwater: important exploratory tools in groundwater surveys. ... Journal of Technology and Education in Nigeria ... An analysis of the spatial variation of these parameters indicates that the EC and pH values of groundwater allow us to make deductions not only on the changes in the ...

  5. Soil water sensor response to bulk electrical conductivity

    Science.gov (United States)

    Soil water monitoring using electromagnetic (EM) sensors can facilitate observations of water content at high temporal and spatial resolutions. These sensors measure soil dielectric permittivity (Ka) which is largely a function of volumetric water content. However, bulk electrical conductivity BEC c...

  6. On the flow dependency of the electrical conductivity of blood

    NARCIS (Netherlands)

    Hoetink, AE; Faes, TJC; Visser, KR; Heethaar, RM

    Experiments presented in the literature show that the electrical conductivity of flowing blood depends on flow velocity. The aim of this study is to extend the Maxwell-Fricke theory, developed for a dilute suspension of ellipsoidal particles in an electrolyte, to explain this flow dependency of the

  7. Mantle electrical conductivity profile of Niger delta region

    Indian Academy of Sciences (India)

    The mantle electrical conductivity-depth profile of the Niger delta region in Nigeria has been determined using solar quiet day ionospheric current (Sq).The magnetometer data obtained in 2010 from geomagnetic stations installed in Lagos by magnetic dataset (MAGDAS) in 2008 and data from magnetometers installed in ...

  8. Influence of electrical conductivity on microorganisms and rate of ...

    African Journals Online (AJOL)

    Salt treatments included NaCI amendments to adjust the soil solution electrical conductivities (EC) to 40, 120 and 200 dSm-1. Treated soils were incubated at 28OC. Oil degradation was estimated from the gravimetric determinations of remaining oil. The results showed that amending the ultisol with crude oil stimulated the ...

  9. Electrical conductivity measurements on gel grown KDP crystals ...

    Indian Academy of Sciences (India)

    Impurity added KDP crystals; gel method; electrical conductivity; activation energy. 1. Introduction. Potassium dihydrogen ... phate [(NH4)2SO4] along with double distilled water and ethyl alcohol were used. KDP was added with .... in the vicinity of electrodes or chemical changes in layers close to electrodes (Bunget and ...

  10. Electrical conductivity of hydrogen shocked to megabar pressures

    International Nuclear Information System (INIS)

    Weir, S.T.; Nellis, W.J.; Mitchell, A.C.

    1993-08-01

    The properties of ultra-high pressure hydrogen have been the subject of much experimental and theoretical study. Of particular interest is the pressure-induced insulator-to-metal transition of hydrogen which, according to recent theoretical calculations, is predicted to occur by band-overlap in the pressure range of 1.5-3.0 Mbars on the zero temperature isotherm. Extremely high pressures are required for metallization since the low-pressure band gap is about 15 eV. Recent static-pressure diamond anvil cell experiments have searched for evidence of an insulator-to-metal transition, but no conclusive evidence for such a transition has yet been supplied. Providing conclusive evidence for hydrogen metallization is difficult because no technique has yet been developed for performing static high-pressure electrical conductivity experiments at megabar pressures. The authors report here on electrical conductivity experiments performed on H 2 and D 2 multi-shocked to megabar pressures. Electrical conductivities of dense fluid hydrogen at these pressures and temperatures reached are needed for calculations of the magnetic fields of Jupiter and Saturn, the magnetic fields being generated by convective dynamos of hot, dense, semiconducting fluid hydrogen. Also, since electrical conduction at the pressure-temperature conditions being studied is due to the thermal excitation of charge carriers across the electronic band gap, these experiments yield valuable information on the width of the band gap at high densities

  11. Year long variability of ground electrical conductivity in the sandy ...

    African Journals Online (AJOL)

    Ground electrical conductivity was measured continuously on a soil type in Nigeria for one year using the Model R-50 Soil Test Resistivity Meter Equipment. The Wenner arrangement of electrodes, which is one of the probe methods of ground resistivity measurement, was employed for the measurement. About 67% of all ...

  12. The variation of electrical conductivity with temperature for Cu ...

    African Journals Online (AJOL)

    ZnS) alloy with temperature has been investigated. The electrical conductivity of the samples increases with temperature and obeys the Arrhenius relation, δ= δ° exp (-Eg/2kT) which is characteristic of semiconductors. The energy gaps ...

  13. Evaluation of electrical and thermal conductivity of polymeric wastes ...

    African Journals Online (AJOL)

    This work being gingered by the big menace being posed on our environment by polymeric waste and it's rechanneling involved the studying of the electrical and thermal conductivities of the polymers PP, PE, PS and nylon66 doped with charcoal and graphite. Five grams of each polymer was mixed with varying ...

  14. High Resolution Global Electrical Conductivity Variations in the Earth's Mantle

    Science.gov (United States)

    Kelbert, A.; Sun, J.; Egbert, G. D.

    2013-12-01

    Electrical conductivity of the Earth's mantle is a valuable constraint on the water content and melting processes. In Kelbert et al. (2009), we obtained the first global inverse model of electrical conductivity in the mantle capable of providing constraints on the lateral variations in mantle water content. However, in doing so we had to compromise on the problem complexity by using the historically very primitive ionospheric and magnetospheric source assumptions. In particular, possible model contamination by the auroral current systems had greatly restricted our use of available data. We have now addressed this problem by inverting for the external sources along with the electrical conductivity variations. In this study, we still focus primarily on long period data that are dominated by quasi-zonal source fields. The improved understanding of the ionospheric sources allows us to invert the magnetic fields directly, without a correction for the source and/or the use of transfer functions. It allows us to extend the period range of available data to 1.2 days - 102 days, achieving better sensitivity to the upper mantle and transition zone structures. Finally, once the source effects in the data are accounted for, a much larger subset of observatories may be used in the electrical conductivity inversion. Here, we use full magnetic fields at 207 geomagnetic observatories, which include mid-latitude, equatorial and high latitude data. Observatory hourly means from the years 1958-2010 are employed. The improved quality and spatial distribution of the data set, as well as the high resolution modeling and inversion using degree and order 40 spherical harmonics mapped to a 2x2 degree lateral grid, all contribute to the much improved resolution of our models, representing a conceptual step forward in global electromagnetic sounding. We present a fully three-dimensional, global electrical conductivity model of the Earth's mantle as inferred from ground geomagnetic

  15. Effect of pH on the electrical properties and conducting mechanism of SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Periathai, R.Sudha [Department of Physics, Standard Fireworks Rajaratnam College for Women, Sivakasi 626123 (India); Abarna, S.; Hirankumar, G. [Centre for Scientific and Applied Research, PSN College of Engineering and Technology, Tirunelveli 627152 (India); Jeyakumaran, N. [Department of Physics, V.H.N. Senthikumara Nadar College, Virudhunagar 626001 (India); Prithivikumaran, N., E-mail: janavi_p@yahoo.com [Department of Physics, V.H.N. Senthikumara Nadar College, Virudhunagar 626001 (India)

    2017-03-15

    Semiconductor nanoparticles have attracted more interests because of their size-dependent optical and electrical properties.SnO{sub 2} is an oxygen-deficient n-type semiconductor with a wide band gap of 3.6 eV (300 K). It has many remarkable applications as sensors, catalysts, transparent conducting electrodes, anode material for rechargeable Li- ion batteries and optoelectronic devices. In the present work, the role of pH in determining the electrical and dielectric properties of SnO{sub 2} nanoparticles has been studied as a function of temperature ranging from Room temperature (RT) to 114 °C in the frequency range of 7 MHz to 50 mHz using impedance spectroscopic technique. The non linear behavior observed in the thermal dependence of the conductance of SnO{sub 2} nanoparticles is explained by means of the surface property of SnO{sub 2} nanoparticles where proton hopping mechanism is dealt with. Jonscher's power law has been fitted for the conductance spectra and the frequency exponent (“s” value) gives an insight about the ac conducting mechanism. The temperature dependence of electrical relaxation phenomenon in the material has been observed. The complex electric modulus analysis indicates the possibility of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation.

  16. Effect of pH on the electrical properties and conducting mechanism of SnO_2 nanoparticles

    International Nuclear Information System (INIS)

    Periathai, R.Sudha; Abarna, S.; Hirankumar, G.; Jeyakumaran, N.; Prithivikumaran, N.

    2017-01-01

    Semiconductor nanoparticles have attracted more interests because of their size-dependent optical and electrical properties.SnO_2 is an oxygen-deficient n-type semiconductor with a wide band gap of 3.6 eV (300 K). It has many remarkable applications as sensors, catalysts, transparent conducting electrodes, anode material for rechargeable Li- ion batteries and optoelectronic devices. In the present work, the role of pH in determining the electrical and dielectric properties of SnO_2 nanoparticles has been studied as a function of temperature ranging from Room temperature (RT) to 114 °C in the frequency range of 7 MHz to 50 mHz using impedance spectroscopic technique. The non linear behavior observed in the thermal dependence of the conductance of SnO_2 nanoparticles is explained by means of the surface property of SnO_2 nanoparticles where proton hopping mechanism is dealt with. Jonscher's power law has been fitted for the conductance spectra and the frequency exponent (“s” value) gives an insight about the ac conducting mechanism. The temperature dependence of electrical relaxation phenomenon in the material has been observed. The complex electric modulus analysis indicates the possibility of hopping conduction mechanism in the system with non-exponential type of conductivity relaxation.

  17. Electric conductivity of TlInTe2 monocrystal in strong electric fields

    International Nuclear Information System (INIS)

    Zarbaliev, M.M.; Godzhaev, Eh.M.; Gadzhiev, V.A.

    1980-01-01

    Electric condUctivity of the TlInTe 2 single crystal in strong electric fields has been studied in the range of 77-300 K. The electron part of the TlInTe 2 dielectric constant has been found to be 4. The dependence of the activation energy of current carriers on the electric field strength is constructed and the value of the activation energy of current carriers in the absence of an electric field is determined by the extrapolation method. The results of the experiments are in good agreement with the Frenkel-Pool theory, and this affords grounds for asserting that the obtained dependences of electric conductivity on temperature and the electric field strength are defined by variation in the current carrier concentration due to action of the thermal-electron ionization mechanism

  18. Predicting permeability and electrical conductivity of sedimentary rocks from microgeometry

    International Nuclear Information System (INIS)

    Schlueter, E.M.; Cook, N.G.W.

    1991-02-01

    The determination of hydrologic parameters that characterize fluid flow through rock masses on a large scale (e.g., hydraulic conductivity, capillary pressure, and relative permeability) is crucial to activities such as the planning and control of enhanced oil recovery operations, and the design of nuclear waste repositories. Hydraulic permeability and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. The cross-sectional areas and perimeters of the individual pores are estimated from two-dimensional scanning electron micrographs of rock sections. The hydraulic and electrical conductivities of the individual pores are determined from these geometrical parameters, using Darcy's law and Ohm's law. Account is taken of the fact that the cross-sections are randomly oriented with respect to the channel axes, and for possible variation of cross-sectional area along the length of the pores. The effective medium theory from solid-state physics is then used to determine an effective average conductance of each pore. Finally, the pores are assumed to be arranged on a cubic lattice, which allows the calculation of overall macroscopic values for the permeability and the electrical conductivity. Preliminary results using Berea, Boise, Massilon and Saint-Gilles sandstones show reasonably close agreement between the predicted and measured transport properties. 12 refs., 5 figs., 1 tab

  19. Microbial interspecies electron transfer via electric currents through conductive minerals

    Science.gov (United States)

    Kato, Souichiro; Hashimoto, Kazuhito; Watanabe, Kazuya

    2012-01-01

    In anaerobic biota, reducing equivalents (electrons) are transferred between different species of microbes [interspecies electron transfer (IET)], establishing the basis of cooperative behaviors and community functions. IET mechanisms described so far are based on diffusion of redox chemical species and/or direct contact in cell aggregates. Here, we show another possibility that IET also occurs via electric currents through natural conductive minerals. Our investigation revealed that electrically conductive magnetite nanoparticles facilitated IET from Geobacter sulfurreducens to Thiobacillus denitrificans, accomplishing acetate oxidation coupled to nitrate reduction. This two-species cooperative catabolism also occurred, albeit one order of magnitude slower, in the presence of Fe ions that worked as diffusive redox species. Semiconductive and insulating iron-oxide nanoparticles did not accelerate the cooperative catabolism. Our results suggest that microbes use conductive mineral particles as conduits of electrons, resulting in efficient IET and cooperative catabolism. Furthermore, such natural mineral conduits are considered to provide ecological advantages for users, because their investments in IET can be reduced. Given that conductive minerals are ubiquitously and abundantly present in nature, electric interactions between microbes and conductive minerals may contribute greatly to the coupling of biogeochemical reactions. PMID:22665802

  20. Electrical insulation and conduction coating for fusion experimental devices

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, Masanori; Tsujimura, Seiji; Toyoda, Masahiko; Inoue, Masahiko [Mitsubishi Heavy Industries, Ltd., Yokohama (Japan); Abe, Tetsuya; Murakami, Yoshio [Japan Atomic Energy Research Inst., Naka (Japan)

    1996-01-01

    The development of electrical insulation and conduction coating methods that can be applied to large components of fusion experimental devices has been investigated. A thermal spraying method is used to coat the insulation or conduction materials on the structural components because of its applicability for large surfaces. The insulation material chosen was Al{sub 2}O{sub 3}, while Cr{sub 3}C{sub 2}-NiCr and WC-NiCr were chosen as conduction materials. These materials were coated on stainless steel substrates to examine the basic characteristics of the coated layers, such as their adhesive strength to the substrate, thermal shock resistance, electrical resistance, dielectric breakdown voltage, and thermal conductivity. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed adequate frictional properties. The spraying method was tested on a 100- x 1000-mm surface and found to be applicable for large surfaces of experimental fusion devices. 9 refs., 6 figs., 15 tabs.

  1. Electrical insulation and conduction coating for fusion experimental devices

    International Nuclear Information System (INIS)

    Onozuka, Masanori; Tsujimura, Seiji; Toyoda, Masahiko; Inoue, Masahiko; Abe, Tetsuya; Murakami, Yoshio

    1996-01-01

    The development of electrical insulation and conduction coating methods that can be applied to large components of fusion experimental devices has been investigated. A thermal spraying method is used to coat the insulation or conduction materials on the structural components because of its applicability for large surfaces. The insulation material chosen was Al 2 O 3 , while Cr 3 C 2 -NiCr and WC-NiCr were chosen as conduction materials. These materials were coated on stainless steel substrates to examine the basic characteristics of the coated layers, such as their adhesive strength to the substrate, thermal shock resistance, electrical resistance, dielectric breakdown voltage, and thermal conductivity. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed adequate frictional properties. The spraying method was tested on a 100- x 1000-mm surface and found to be applicable for large surfaces of experimental fusion devices. 9 refs., 6 figs., 15 tabs

  2. Apparatus for simultaneously measuring electrical conductivity and oxygen fugacity

    Energy Technology Data Exchange (ETDEWEB)

    Netherton, R.; Duba, A.

    1978-01-31

    Electrical conductivity studies of silicates are useful in determining temperature vs depth in the earth. Realistic laboratory measurements of conduction mechanisms require that exact determinations of oxygen fugacity (fo{sub 2}) be made in the experimental environment. An apparatus is described that monitors system fo{sub 2} with a calcia-doped zirconia-oxygen cell while measuring electrical conductivity of iron-bearing silicates at high temperature (greater than 1000 K). The fo{sub 2} calculated thermodynamically from CO/CO{sub 2} mixing ratios agreed well with measurements made with the zirconia cell at 1473 K, except for fo{sub 2} greater than 10{sup -4} Pa, where, on a log{sub 10} scale, mixing-ratio errors were as large as +- 0.2. These errors are attributed to oxygen contamination in the CO{sub 2} and to mobile carbon deposits that formed in the apparatus.

  3. Modeling electrical conductivities of nanocomposites with aligned carbon nanotubes

    International Nuclear Information System (INIS)

    Bao, W S; Meguid, S A; Zhu, Z H; Meguid, M J

    2011-01-01

    We have developed an improved three-dimensional (3D) percolation model to investigate the effect of the alignment of carbon nanotubes (CNTs) on the electrical conductivity of nanocomposites. In this model, both intrinsic and contact resistances are considered, and a new method of resistor network recognition that employs periodically connective paths is developed. This method leads to a reduction in the size effect of the representative cuboid in our Monte Carlo simulations. With this new technique, we were able to effectively analyze the effects of the CNT alignment upon the electrical conductivity of nanocomposites. Our model predicted that the peak value of the conductivity occurs for partially aligned rather than perfectly aligned CNTs. It has also identified the value of the peak and the corresponding alignment for different volume fractions of CNTs. Our model works well for both multi-wall CNTs (MWCNTs) and single-wall CNTs (SWCNTs), and the numerical results show a quantitative agreement with existing experimental observations.

  4. Enhanced AC conductivity and dielectric relaxation properties of polypyrrole nanoparticles irradiated with Ni{sup 12+} swift heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Hazarika, J.; Kumar, A., E-mail: ask@tezu.ernet.in

    2014-08-15

    In this paper, we report the 160 MeV Ni{sup 12+} swift heavy ions (SHIs) irradiation effects on AC conductivity and dielectric relaxation properties of polypyrrole (PPy) nanoparticles in the frequency range of 42 Hz–5 MHz. Four ion fluences of 5 × 10{sup 10}, 1 × 10{sup 11}, 5 × 10{sup 11} and 1 × 10{sup 12} ions/cm{sup 2} have been used for the irradiation purpose. Transport properties in the pristine and irradiated PPy nanoparticles have been investigated with permittivity and modulus formalisms to study the polarization effects and conductivity relaxation. With increasing ion fluence, the relaxation peak in imaginary modulus (M{sup ″}) plots shifts toward high frequency suggesting long range motion of the charge carriers. The AC conductivity studies suggest correlated barrier hopping as the dominant transport mechanism. The hopping distance (R{sub ω}) of the charge carriers decreases with increasing the ion fluence. Binding energy (W{sub m}) calculations depict that polarons are the dominant charge carriers.

  5. Leaching of Conductive Species: Implications to Measurements of Electrical Resistivity.

    Science.gov (United States)

    Spragg, R; Jones, S; Bu, Y; Lu, Y; Bentz, D; Snyder, K; Weiss, J

    2017-05-01

    Electrical tests have been used to characterize the microstructure of porous materials, the measured electrical response being determined by the contribution of the microstructure (porosity and tortuosity) and the electrical properties of the solution (conductivity of the pore solution) inside the pores of the material. This study has shown how differences in concentration between the pore solution (i.e., the solution in the pores) and the storage solution surrounding the test specimen leads to significant transport (leaching) of the conductive ionic species between the pore solution and the storage solution. Leaching influences the resistivity of the pore solution, thereby influencing electrical measurements on the bulk material from either a surface or uniaxial bulk resistance test. This paper has three main conclusions: 1.) Leaching of conductive species does occur with concentration gradients and that a diffusion based approach can be used to estimate the time scale associated with this change. 2.) Leaching of ions in the pore solution can influence resistivity measurements, and the ratio of surface to uniaxial resistivity can be used as a method to assess the presence of leaching and 3.) An estimation of the magnitude of leaching for standardized tests of cementitious materials.

  6. Experimental study of electric field influence on low temperature long-time relaxation in crystalline ferroelectrics

    International Nuclear Information System (INIS)

    Sahling, S.; Kolac, M.; Sahling, A.

    1987-01-01

    Calorimetric measurements with polycrystalline Pb 0.915 La 0.085 x(Zr 0.65 Ti 0.35 )O 3 were performed at helium temperatures in electric field E (0 ≤ E ≤ 4.3 kV/cm). Heat release after cooling from T 1 (1.3 K ≤ T 1 ≤ 35 K) to T 0 =1.3 K is very similar to that in amorphous metals and dielectrics. Experimental results disagree with the standard tunneling model. The observed release may be explained assuming the existence of a maximum energy is an element of f in the distribution function. The maximum relaxation time τ max was found as a function of T 1 . A similar heat release is observed after switching on or off the electric field. In dependent of T for 1.1 K ≤ T ≤ 3 K, proportional to E 2 with τ max ∼ E. No heat release was observed in the KH 2 PO 4 single crystal

  7. Electric field dependence of excess electrical conductivity below transition temperature in thin superconducting lead films

    Energy Technology Data Exchange (ETDEWEB)

    Ashwini Kumar, P K; Duggal, V P [Delhi Univ. (India). Dept. of Physics and Astrophysics

    1976-01-26

    Results of measurements of the electric field dependence of the excess electrical conductivity are reported in thin superconducting lead films below the transition temperature. It is observed that the normal state sheet resistance has some effect on the nonlinearity but the theory of Yamaji still fits well to the experimental data.

  8. Modelling electrical conductivity of groundwater using an adaptive neuro-fuzzy inference system

    NARCIS (Netherlands)

    B. Tutmez (Bulent); Z. Hatipoglu (Z.); U. Kaymak (Uzay)

    2006-01-01

    textabstractElectrical conductivity is an important indicator for water quality assessment. Since the composition of mineral salts affects the electrical conductivity of groundwater, it is important to understand the relationships between mineral salt composition and electrical conductivity. In this

  9. Modelling electrical conductivity of groundwater using and adaptive neuro-fuzzy inference system

    NARCIS (Netherlands)

    Tutmez, B.; Hatipoglu, Z.; Kaymak, U.

    2006-01-01

    Electrical conductivity is an important indicator for water quality assessment. Since the composition of mineral salts affects the electrical conductivity of groundwater, it is important to understand the relationships between mineral salt composition and electrical conductivity. In this present

  10. Noninvasive electrical conductivity measurement by MRI: a test of its validity and the electrical conductivity characteristics of glioma.

    Science.gov (United States)

    Tha, Khin Khin; Katscher, Ulrich; Yamaguchi, Shigeru; Stehning, Christian; Terasaka, Shunsuke; Fujima, Noriyuki; Kudo, Kohsuke; Kazumata, Ken; Yamamoto, Toru; Van Cauteren, Marc; Shirato, Hiroki

    2018-01-01

    This study noninvasively examined the electrical conductivity (σ) characteristics of diffuse gliomas using MRI and tested its validity. MRI including a 3D steady-state free precession (3D SSFP) sequence was performed on 30 glioma patients. The σ maps were reconstructed from the phase images of the 3D SSFP sequence. The σ histogram metrics were extracted and compared among the contrast-enhanced (CET) and noncontrast-enhanced tumour components (NCET) and normal brain parenchyma (NP). Difference in tumour σ histogram metrics among tumour grades and correlation of σ metrics with tumour grades were tested. Validity of σ measurement using this technique was tested by correlating the mean tumour σ values measured using MRI with those measured ex vivo using a dielectric probe. Several σ histogram metrics of CET and NCET of diffuse gliomas were significantly higher than NP (Bonferroni-corrected p ≤ .045). The maximum σ of NCET showed a moderate positive correlation with tumour grade (r = .571, Bonferroni-corrected p = .018). The mean tumour σ measured using MRI showed a moderate positive correlation with the σ measured ex vivo (r = .518, p = .040). Tissue σ can be evaluated using MRI, incorporation of which may better characterise diffuse gliomas. • This study tested the validity of noninvasive electrical conductivity measurements by MRI. • This study also evaluated the electrical conductivity characteristics of diffuse glioma. • Gliomas have higher electrical conductivity values than the normal brain parenchyma. • Noninvasive electrical conductivity measurement can be helpful for better characterisation of glioma.

  11. Electrically conducting nanobiocomposites using carbon nanotubes and collagen waste fibers

    International Nuclear Information System (INIS)

    Meiyazhagan, Ashokkumar; Thangavel, Saravanamoorthy; Hashim, Daniel P.; Ajayan, Pulickel M.; Palanisamy, Thanikaivelan

    2015-01-01

    Electrically conducting hybrid biocomposite films were prepared using a simple and cost-effective method by incorporating different types of carbon nanotubes (XCNTs) viz., few walled carbon nanotube (FWCNT) and boron doped carbon nanotube (BCNT) into biopolymers. Collagen extracted from animal skin wastes was blended with guar gum and XCNTs in varying proportions to form flexible and electrically conducting hybrid films. We found that the electrical conductivity of both types of hybrid films increases radically as the XCNT loading increases. BCNT incorporated hybrid films show better electrical conductivity (3.0 × 10 −1 S/cm) than their FWCNT loaded counter parts (4.8 × 10 −4 S/cm) at a dosage of 2 wt.%. On the other hand, mechanical and other physical properties such as transparency, flexibility and surface smoothness of the developed hybrid films were affected as a function of XCNT concentration. We also demonstrated that the developed hybrid films lit up a LED lamp when inserted between batteries and the brightness of the emitted light depended on the XCNT loading. These results suggest a new way to transform an industrial biowaste into innovative advanced materials for applications in fields related to biomedicine, biosensors and electronics. - Highlights: • Hybrid nanobiocomposite films prepared using collagen, guar gum and CNTs. • Examined the effect of CNT doping on the properties of hybrid biocomposite films. • Higher CNT loading improved the conductivity radically, especially for BCNT. • The ability of developed hybrid films to lit up a LED lamp was demonstrated. • The results suggest a new way to transform biowaste into advanced materials

  12. Dielectric relaxation and ionic conductivity studies of Na 2 ZnP 2 O 7

    Indian Academy of Sciences (India)

    The Na2ZnP2O7 compound was obtained by the conventional solid-state reaction. The sample was characterized by X-ray powder diffraction, infrared analysis and electrical impedance spectroscopy. The impedance plots show semicircle arcs at different temperatures and an electrical equivalent circuit has been proposed ...

  13. Electrokinetic properties and conductance relaxation of polystyrene and silver iodide plugs

    NARCIS (Netherlands)

    Hoven, van den J.J.

    1984-01-01

    This thesis describes an experimental study on the electrokinetic and electrical properties of concentrated polystyrene and silver iodide dispersions. The purpose of the study is to obtain information on the structure of the electrical double layer at the solid-liquid interface. Special

  14. Nonideal ultrathin mantle cloak for electrically large conducting cylinders.

    Science.gov (United States)

    Liu, Shuo; Zhang, Hao Chi; Xu, He-Xiu; Cui, Tie Jun

    2014-09-01

    Based on the concept of the scattering cancellation technique, we propose a nonideal ultrathin mantle cloak that can efficiently suppress the total scattering cross sections of an electrically large conducting cylinder (over one free-space wavelength). The cloaking mechanism is investigated in depth based on the Mie scattering theory and is simultaneously interpreted from the perspective of far-field bistatic scattering and near-field distributions. We remark that, unlike the perfect transformation-optics-based cloak, this nonideal cloaking technique is mainly designed to minimize simultaneously several scattering multipoles of a relatively large geometry around considerably broad bandwidth. Numerical simulations and experimental results show that the antiscattering ability of the metasurface gives rise to excellent total scattering reduction of the electrically large cylinder and remarkable electric-field restoration around the cloak. The outstanding cloaking performance together with the good features of and ultralow profile, flexibility, and easy fabrication predict promising applications in the microwave frequencies.

  15. Facile synthesis of degradable and electrically conductive polysaccharide hydrogels.

    Science.gov (United States)

    Guo, Baolin; Finne-Wistrand, Anna; Albertsson, Ann-Christine

    2011-07-11

    Degradable and electrically conductive polysaccharide hydrogels (DECPHs) have been synthesized by functionalizing polysaccharide with conductive aniline oligomers. DECPHs based on chitosan (CS), aniline tetramer (AT), and glutaraldehyde were obtained by a facile one-pot reaction by using the amine group of CS and AT under mild conditions, which avoids the multistep reactions and tedious purification involved in the synthesis of degradable conductive hydrogels in our previous work. Interestingly, these one-pot hydrogels possess good film-forming properties, electrical conductivity, and a pH-sensitive swelling behavior. The chemical structure and morphology before and after swelling of the hydrogels were verified by FT-IR, NMR, and SEM. The conductivity of the hydrogels was tuned by adjusting the content of AT. The swelling ratio of the hydrogels was altered by the content of tetraaniline and cross-linker. The hydrogels underwent slow degradation in a buffer solution. The hydrogels obtained by this facile approach provide new possibilities in biomedical applications, for example, biodegradable conductive hydrogels, films, and scaffolds for cardiovascular tissue engineering and controlled drug delivery.

  16. Nanostructure design for drastic reduction of thermal conductivity while preserving high electrical conductivity.

    Science.gov (United States)

    Nakamura, Yoshiaki

    2018-01-01

    The design and fabrication of nanostructured materials to control both thermal and electrical properties are demonstrated for high-performance thermoelectric conversion. We have focused on silicon (Si) because it is an environmentally friendly and ubiquitous element. High bulk thermal conductivity of Si limits its potential as a thermoelectric material. The thermal conductivity of Si has been reduced by introducing grains, or wires, yet a further reduction is required while retaining a high electrical conductivity. We have designed two different nanostructures for this purpose. One structure is connected Si nanodots (NDs) with the same crystal orientation. The phonons scattering at the interfaces of these NDs occurred and it depended on the ND size. As a result of phonon scattering, the thermal conductivity of this nanostructured material was below/close to the amorphous limit. The other structure is Si films containing epitaxially grown Ge NDs. The Si layer imparted high electrical conductivity, while the Ge NDs served as phonon scattering bodies reducing thermal conductivity drastically. This work gives a methodology for the independent control of electron and phonon transport using nanostructured materials. This can bring the realization of thermoelectric Si-based materials that are compatible with large scale integrated circuit processing technologies.

  17. Electrical conductivities and chemical stabilities of mixed conducting pyrochlores for SOFC applications

    DEFF Research Database (Denmark)

    Holtappels, P.; Poulsen, F.W.; Mogensen, Mogens Bjerg

    2000-01-01

    Pyrochlores with praseodymium as the A-site cation and zirconium, tin, cerium and manganese cations on the B-site were prepared in air and their electrical conductivities were investigated as a function of oxygen partial pressure and temperature. Pure Pr2Zr2O7+/-delta as well as samples modified...

  18. Thermal and electrical conductivities of high purity tantalum

    International Nuclear Information System (INIS)

    Archer, S.L.

    1978-01-01

    The electrical resistivity and thermal conductivity of three high purity tantalum samples have been measured as functions of temperature over a temperature range of 5K to 65K. Sample purities ranged up to a resistivity ratio of 1714. The highest purity sample had a residual resistivity of .76 x 10 -10 OMEGA-m. The intrinsic resistivity varied as T 3 . 9 from 10K to 31K. The thermal conductivity of the purest sample had a maximum of 840 W/mK at 9.8K. The intrinsic thermal resistivity varied as T 2 . 4 from 10K to 35K. At low temperatures electrons were scattered primarily by impurities and by phonons with both interband and intraband transitions observed. The electrical and thermal resistivity is departed from Matthiessen's rule at low temperatures

  19. Measurement of temperature, electric conductivity and density of plasma

    International Nuclear Information System (INIS)

    Vasilevova, I.; Nefedov, A.; Oberman, F.; Urinson, A.

    1982-01-01

    Three instruments are briefly described developed by the High Temperatures Institute of the USSR Academy of Sciences for the measurement of plasma temperature, electric conductivity and density. The temperature measuring instrument uses as a standard a light source whose temperature may significantly differ from plasma temperature because three light fluxes are compared, namely the flux emitted by the plasma, the flux emitted directly by the standard source, and the flux emitted by the standard source after passage through the plasma. The results of measurement are computer processed. Electric conductivity is measured using a coil placed in a probe which is automatically extended for a time of maximally 0.3 seconds into the plasma stream. The equipment for measuring plasma density consists of a special single-channel monochromator, a temperature gauge, a plasma pressure gauge, and of a computer for processing the results of measurement. (Ha)

  20. Evaluation of electrical conductivity of the fertiliser solution on ...

    African Journals Online (AJOL)

    The effects of three fertiliser solutions (20:20:20, 15:5:25 and 12:30:10 NPK) with electrical conductivity (EC) of 1, 1.5 or 2 mS cm-1 on growth and flowering of Cymbidium 'Sleeping Nymph' were investigated over three years. One-year-old tissue-cultured propagules of 'Sleeping Nymph' were planted singly in plastic pots in ...

  1. Electrical actuation of electrically conducting and insulating droplets using ac and dc voltages

    International Nuclear Information System (INIS)

    Kumari, N; Bahadur, V; Garimella, S V

    2008-01-01

    Electrical actuation of liquid droplets at the microscale offers promising applications in the fields of microfluidics and lab-on-chip devices. Much prior research has targeted the electrical actuation of electrically conducting liquid droplets using dc voltages (classical electrowetting). Electrical actuation of conducting droplets using ac voltages and the actuation of insulating droplets (using dc or ac voltages) has remained relatively unexplored. This paper utilizes an energy-minimization-based analytical framework to study the electrical actuation of a liquid droplet (electrically conducting or insulating) under ac actuation. It is shown that the electromechanical regimes of classical electrowetting, electrowetting under ac actuation and insulating droplet actuation can be extracted from the generic electromechanical actuation framework, depending on the electrical properties of the droplet, the underlying dielectric layer and the frequency of the actuation voltage. This paper also presents experiments which quantify the influence of the ac frequency and the electrical properties of the droplet on its velocity under electrical actuation. The velocities of droplets moving between two parallel plates under ac actuation are experimentally measured; these velocities are then related to the actuation force on the droplet which is predicted by the electromechanical model developed in this work. It is seen that the droplet velocities are strongly dependent on the frequency of the ac actuation voltage; the cut-off ac frequency, above which the droplet fails to actuate, is experimentally determined and related to the electrical conductivity of the liquid. This paper then analyzes and directly compares the various electromechanical regimes for the actuation of droplets in microfluidic applications

  2. State of hydration and electrical conductance of ichthyotic skin

    OpenAIRE

    A B Gupta; Manisha Bhattacharya; B Haldar

    1990-01-01

    Dry skin of twelve subjects suffering from ichthyosis vulgaris and the efficacy of a moisturiser-Cotaryl were quantitatively assessed by measuring the skin surface hydration and high frequency (3.5 MHz) electrical conductance of skin. The state of hydration and conductance of ichthyotic skin were 86.9 + 24.6 and 11.0 + 5.7 micro-mho respectively, being much less-compared to 132. 0 + 5.3 and 72.5 + 54.0 micro-mho ofnormal subjects. The moisturiser increased the state of hydration and also the ...

  3. The Thermal Electrical Conductivity Probe (TECP) for Phoenix

    Science.gov (United States)

    Zent, Aaron P.; Hecht, Michael H.; Cobos, Doug R.; Campbell, Gaylon S.; Campbell, Colin S.; Cardell, Greg; Foote, Marc C.; Wood, Stephen E.; Mehta, Manish

    2009-01-01

    The Thermal and Electrical Conductivity Probe (TECP) is a component of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) payload on the Phoenix Lander. TECP will measure the temperature, thermal conductivity and volumetric heat capacity of the regolith. It will also detect and quantify the population of mobile H2O molecules in the regolith, if any, throughout the polar summer, by measuring the electrical conductivity of the regolith, as well as the dielectric permittivity. In the vapor phase, TECP is capable of measuring the atmospheric H2O vapor abundance, as well as augment the wind velocity measurements from the meteorology instrumentation. TECP is mounted near the end of the 2.3 m Robotic Arm, and can be placed either in the regolith material or held aloft in the atmosphere. This paper describes the development and calibration of the TECP. In addition, substantial characterization of the instrument has been conducted to identify behavioral characteristics that might affect landed surface operations. The greatest potential issue identified in characterization tests is the extraordinary sensitivity of the TECP to placement. Small gaps alter the contact between the TECP and regolith, complicating data interpretation. Testing with the Phoenix Robotic Arm identified mitigation techniques that will be implemented during flight. A flight model of the instrument was also field tested in the Antarctic Dry Valleys during the 2007-2008 International Polar year. 2

  4. Electrical Conductivity Distributions in Discrete Fluid-Filled Fractures

    Science.gov (United States)

    James, S. C.; Ahmmed, B.; Knox, H. A.; Johnson, T.; Dunbar, J. A.

    2017-12-01

    It is commonly asserted that hydraulic fracturing enhances permeability by generating new fractures in the reservoir. Furthermore, it is assumed that in the fractured system predominant flow occurs in these newly formed and pre-existing fractures. Among the phenomenology that remains enigmatic are fluid distributions inside fractures. Therefore, determining fluid distribution and their associated temporal and spatial evolution in fractures is critical for safe and efficient hydraulic fracturing. Previous studies have used both forward modeling and inversion of electrical data to show that a geologic system consisting of fluid filled fractures has a conductivity distribution, where fractures act as electrically conductive bodies when the fluids are more conductive than the host material. We will use electrical inversion for estimating electrical conductivity distribution within multiple fractures from synthetic and measured data. Specifically, we will use data and well geometries from an experiment performed at Blue Canyon Dome in Socorro, NM, which was used as a study site for subsurface technology, engineering, and research (SubTER) funded by DOE. This project used a central borehole for energetically stimulating the system and four monitoring boreholes, emplaced in the cardinal directions. The electrical data taken during this project used 16 temporary electrodes deployed in the stimulation borehole and 64 permanent electrodes in the monitoring wells (16 each). We present results derived using E4D from scenarios with two discrete fractures, thereby discovering the electric potential response of both spatially and temporarily variant fluid distribution and the resolution of fluid and fracture boundaries. These two fractures have dimensions of 3m × 0.01m × 7m and are separated by 1m. These results can be used to develop stimulation and flow tests at the meso-scale that will be important for model validation. Sandia National Laboratories is a multi

  5. The electrical properties and relaxation behavior of AgNb{sub 1/2}Ta{sub 1/2}O{sub 3} ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Prasad, K.Ganga, E-mail: kotagirigangaprasad@gmail.com; Niranjan, Manish K.; Asthana, Saket

    2017-02-01

    Polycrystalline AgNb{sub 1/2}Ta{sub 1/2}O{sub 3} powder was prepared by solid state reaction method. Preliminary x-ray diffractogram analysis of some aspects of crystal structure showed that a single phase compound formed exhibiting a monoclinic system. Impedance spectroscopy showed the presence of both bulk and grain boundary effects in the material. The relaxation behavior was studied by fitting electric modulus with Bergman function confirms us the existence of non-Debye type of relaxation the material. The ac conductivity spectrum obeyed Funke's double power law and fitting in results, the hopping parameters n{sub 1},n{sub 2} were indicating the existence of small and large range polaron hopping in the material. The band gap of the material 3.02 eV measured by using UV visible spectroscopy.

  6. Comparison of electrical conductivity calculation methods for natural waters

    Science.gov (United States)

    McCleskey, R. Blaine; Nordstrom, D. Kirk; Ryan, Joseph N.

    2012-01-01

    The capability of eleven methods to calculate the electrical conductivity of a wide range of natural waters from their chemical composition was investigated. A brief summary of each method is presented including equations to calculate the conductivities of individual ions, the ions incorporated, and the method's limitations. The ability of each method to reliably predict the conductivity depends on the ions included, effective accounting of ion pairing, and the accuracy of the equation used to estimate the ionic conductivities. The performances of the methods were evaluated by calculating the conductivity of 33 environmentally important electrolyte solutions, 41 U.S. Geological Survey standard reference water samples, and 1593 natural water samples. The natural waters tested include acid mine waters, geothermal waters, seawater, dilute mountain waters, and river water impacted by municipal waste water. The three most recent conductivity methods predict the conductivity of natural waters better than other methods. Two of the recent methods can be used to reliably calculate the conductivity for samples with pH values greater than about 3 and temperatures between 0 and 40°C. One method is applicable to a variety of natural water types with a range of pH from 1 to 10, temperature from 0 to 95°C, and ionic strength up to 1 m.

  7. Redox transitions in strontium vanadates: Electrical conductivity and dimensional changes

    International Nuclear Information System (INIS)

    Macías, J.; Yaremchenko, A.A.; Frade, J.R.

    2014-01-01

    Highlights: • Electrical conductivity and thermal expansion of strontium vanadates are measured. • Conductivity of SrVO 3−δ is 10 6 –10 8 times higher compared to Sr 2 V 2 O 7 and Sr 3 V 2 O 8 . • Sr 2 V 2 O 7 transforms on reduction to SrVO 3−δ via (5Sr 3 V 2 O 8 + SrV 6 O 11 ) intermediate. • This process is kinetically stagnated due to good redox stability of Sr 3 V 2 O 8 . • Large volume changes on Sr 2 V 2 O 7 ↔ SrVO 3 transformation are confirmed by dilatometry. - Abstract: The reversibility of redox-induced phase transformations and accompanying electrical conductivity and dimensional changes in perovskite-type SrVO 3−δ , a parent material for a family of potential solid oxide fuel cell anode materials, were evaluated employing X-ray diffraction, thermal analysis, dilatometry and electrical measurements. At 873–1273 K, the electrical conductivity of SrVO 3−δ is metallic-like and 6–8 orders of magnitude higher compared to semiconducting V 5+ -based strontium pyrovanadate Sr 2 V 2 O 7 and strontium orthovanadate Sr 3 V 2 O 8 existing under oxidizing conditions. SrVO 3−δ is easily oxidized to a pyrovanadate phase at atmospheric oxygen pressure. Inverse reduction in 10%H 2 –90%N 2 atmosphere occurs in two steps through (5Sr 3 V 2 O 8 + SrV 6 O 11 ) intermediate. As Sr 3 V 2 O 8 is relatively stable even under reducing conditions, the perovskite phase and its high level of electrical conductivity cannot be recovered completely in a reasonable time span at temperatures ⩽1273 K. Dilatometric studies confirmed that SrVO 3 ↔ Sr 2 V 2 O 7 redox transformation is accompanied with significant dimensional changes. Their extent depends on the degree of phase conversion and, apparently, on microstructural features

  8. Electrical conductivity imaging in the western Pacific subduction zone

    Science.gov (United States)

    Utada, Hisashi; Baba, Kiyoshi; Shimizu, Hisayoshi

    2010-05-01

    Oceanic plate subduction is an important process for the dynamics and evolution of the Earth's interior, as it is regarded as a typical downward flow of the mantle convection that transports materials from the near surface to the deep mantle. Recent seismological study showed evidence suggesting the transportation of a certain amount of water by subduction of old oceanic plate such as the Pacific plate down to 150-200 km depth into the back arc mantle. However it is not well clarified how deep into the mantle the water can be transported. The electromagnetic induction method to image electrical conductivity distribution is a possible tool to answer this question as it is known to be sensitive to the presence of water. Here we show recent result of observational study from the western Pacific subduction zone to examine the electrical conductivity distribution in the upper mantle and in the mantle transition zone (MTZ), which will provide implications how water distributes in the mantle. We take two kinds of approach for imaging the mantle conductivity, (a) semi-global and (b) regional induction approaches. Result may be summarized as follows: (a) Long (5-30 years) time series records from 8 submarine cables and 13 geomagnetic observatories in the north Pacific region were analyzed and long period magnetotelluric (MT) and geomagnetic deep sounding (GDS) responses were estimated in the period range from 1.7 to 35 days. These frequency dependent response functions were inverted to 3-dimensional conductivity distribution in the depth range between 350 and 850 km. Three major features are suggested in the MTZ depth such as, (1) a high conductivity anomaly beneath the Philippine Sea, (2) a high conductivity anomaly beneath the Hawaiian Islands, and (3) a low conductivity anomaly beneath and in the vicinity of northern Japan. (b) A three-year long deployment of ocean bottom electro-magnetometers (OBEM's) was conducted in the Philippine Sea and west Pacific Ocean from 2005

  9. Magnetic resonance electrical impedance tomography for measuring electrical conductivity during electroporation

    International Nuclear Information System (INIS)

    Kranjc, M; Miklavčič, D; Bajd, F; Serša, I

    2014-01-01

    The electroporation effect on tissue can be assessed by measurement of electrical properties of the tissue undergoing electroporation. The most prominent techniques for measuring electrical properties of electroporated tissues have been voltage–current measurement of applied pulses and electrical impedance tomography (EIT). However, the electrical conductivity of tissue assessed by means of voltage–current measurement was lacking in information on tissue heterogeneity, while EIT requires numerous additional electrodes and produces results with low spatial resolution and high noise. Magnetic resonance EIT (MREIT) is similar to EIT, as it is also used for reconstruction of conductivity images, though voltage and current measurements are not limited to the boundaries in MREIT, hence it yields conductivity images with better spatial resolution. The aim of this study was to investigate and demonstrate the feasibility of the MREIT technique for assessment of conductivity images of tissues undergoing electroporation. Two objects were investigated: agar phantoms and ex vivo liver tissue. As expected, no significant change of electrical conductivity was detected in agar phantoms exposed to pulses of all used amplitudes, while a considerable increase of conductivity was measured in liver tissue exposed to pulses of different amplitudes. (paper)

  10. Electrically conductive carbon nanofiber/paraffin wax composites for electric thermal storage

    International Nuclear Information System (INIS)

    Zhang Kun; Han Baoguo; Yu Xun

    2012-01-01

    Highlights: ► Carbon nanofiber (CNF)/paraffin wax composite is found to be a promising electric thermal storage material. ► The thermal storage capacity of CNF/paraffin wax composite is five times of traditional electric thermal storage material. ► CNF is shown to be an effective conductive filler for the composite. - Abstract: The research of electric thermal storage (ETS) has attracted a lot of attention recently, which converts off-peak electrical energy into thermal energy and release it later at peak hours. In this study, new electric thermal storage composites are developed by employing paraffin wax as thermal storage media and carbon nanofiber (CNF) as conductive fillers. Electric heating and thermal energy release performances of the CNF/paraffin wax composites are experimentally investigated. Experimental results show that, when the composites are heated to about 70 °C, the developed electrically conductive CNF/paraffin wax composites present a thermal storage capacity of about 280 kJ/kg, which is five times of that of traditional thermal storage medium such as ceramic bricks (54 kJ/kg). The CNF/paraffin wax composites can also effectively store the thermal energy and release the thermal energy in later hours.

  11. Electrical studies on silver based fast ion conducting glassy materials

    International Nuclear Information System (INIS)

    Rao, B. Appa; Kumar, E. Ramesh; Kumari, K. Rajani; Bhikshamaiah, G.

    2014-01-01

    Among all the available fast ion conductors, silver based glasses exhibit high conductivity. Further, glasses containing silver iodide enhances fast ion conducting behavior at room temperature. Glasses of various compositions of silver based fast ion conductors in the AgI−Ag 2 O−[(1−x)B 2 O 3 −xTeO 2 ] (x=0 to1 mol% in steps of 0.2) glassy system have been prepared by melt quenching method. The glassy nature of the compounds has been confirmed by X-ray diffraction. The electrical conductivity (AC) measurements have been carried out in the frequency range of 1 KHz–3MHz by Impedance Analyzer in the temperature range 303–423K. The DC conductivity measurements were also carried out in the temperature range 300–523K. From both AC and DC conductivity studies, it is found that the conductivity increases and activation energy decreases with increasing the concentration of TeO 2 as well as with temperature. The conductivity of the present glass system is found to be of the order of 10 −2 S/cm at room temperature. The ionic transport number of these glasses is found to be 0.999 indicating that these glasses can be used as electrolyte in batteries

  12. Synthesis and electrical conductivity of nanocrystalline tetragonal FeS

    International Nuclear Information System (INIS)

    Zeng Shu-Lin; Wang Hui-Xian; Dong Cheng

    2014-01-01

    A convenient method for synthesis of tetragonal FeS using iron powder as iron source, is reported. Nanocrystalline tetragonal FeS samples were successfully synthesized by reacting metallic iron powder with sodium sulfide in acetate buffer solution. The obtained sample is single-phase tetragonal FeS with lattice parameters a = 0.3767 nm and c = 0.5037 nm, as revealed by X-ray diffraction. The sample consists of flat nanosheets with lateral dimensions from 20 nm up to 200 nm and average thickness of about 20 nm. We found that tetragonal FeS is a fairly good conductor from the electrical resistivity measurement on a pellet of the nanosheets. The temperature dependence of conductivity of the pellet was well fitted using an empirical equation wherein the effect of different grain boundaries was taken into consideration. This study provides a convenient, economic way to synthesize tetragonal FeS in a large scale and reports the first electrical conductivity data for tetragonal FeS down to liquid helium temperature. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. Low frequency ac conduction and dielectric relaxation in poly(N ...

    Indian Academy of Sciences (India)

    The ac conductivity and dielectric constant of poly(N-methyl pyrrole) thin films have been investigated in the temperature range 77–350 K and in the frequency range 102–106 Hz. The well defined loss peaks have been observed in the temperature region where measured ac conductivity approaches dc conductivity.

  14. Electrical Conductivity of Metals: A New Look at this Subject

    Directory of Open Access Journals (Sweden)

    Silva P. R.

    2014-04-01

    Full Text Available Various parameters tied to the electrical conductivity of typical metals are estimated and are expressed in terms of universal constants. It happen s that they are close to those found in metallic copper at room temperature. The fact that the realization of the model occurs at room temperature is explained by using th e Landauer’s erasure principle. The averaged collision time of the electron of conduction is also thought as a particle lifetime. Finally an analogy is established between the motion of the electron of conduction and the cosmological constant problem, where a spherical surface of radius equal to the electron mean free path has been thought as a surf ace horizon for the charge carriers.

  15. Influence of SiO{sub 2} on conduction and relaxation mechanism of Li{sup +} ions in binary network former lead silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ahlawat, Navneet [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055, Haryana (India); Ahlawat, Neetu, E-mail: neetugju@yahoo.co.in [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar 125001, Haryana (India); Aghamkar, Praveen [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055, Haryana (India); Agarwal, Ashish; Sanghi, Sujata; Sindhu, Monica [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar 125001, Haryana (India)

    2013-04-01

    Ion conducting glasses having composition 30Li{sub 2}O·(70−x)PbO·xSiO{sub 2} were prepared by the normal melt quench technique. The compositional variations in density, molar volume and glass transition temperature confirm the dual role of PbO acting as a network modifying oxide as well as a network forming oxide. Conduction and relaxation mechanisms in these glasses were studied using impedance spectroscopy in the frequency range from 1 Hz to 7 MHz and in a temperature range below glass transition temperature. The ac and dc conductivities, activation energy of the dc conductivity and relaxation frequency were extracted from the impedance spectra. Similar values of activation energy for dc conduction and for conductivity relaxation time indicate that the ions have to overcome the same energy barrier while conducting and relaxing. The increase in dc conductivity for silica rich compositions is attributed to the presence of mixed former effect in the studied glasses. The study of conductivity spectra reveals a transition from non-random to random hopping motion of lithium ions on successive replacement of PbO by SiO{sub 2} in glass matrix. The conduction and relaxation mechanism in the studied glasses are well explained with the concept of mismatch and relaxation (CMR) model.

  16. Electrically conductive biodegradable polymer composite for nerve regeneration: electricity-stimulated neurite outgrowth and axon regeneration.

    Science.gov (United States)

    Zhang, Ze; Rouabhia, Mahmoud; Wang, Zhaoxu; Roberge, Christophe; Shi, Guixin; Roche, Phillippe; Li, Jiangming; Dao, Lê H

    2007-01-01

    Normal and electrically stimulated PC12 cell cultures and the implantation of nerve guidance channels were performed to evaluate newly developed electrically conductive biodegradable polymer composites. Polypyrrole (PPy) doped by butane sulfonic acid showed a significantly higher number of viable cells compared with PPy doped by polystyrenesulfonate after a 6-day culture. The PC12 cells were left to proliferate for 6 days, and the PPy-coated membranes, showing less initial cell adherence, recorded the same proliferation rate as did the noncoated membranes. Direct current electricity at various intensities was applied to the PC12 cell-cultured conductive membranes. After 7 days, the greatest number of neurites appeared on the membranes with a current intensity approximating 1.7-8.4 microA/cm. Nerve guidance channels made of conductive biodegradable composite were implanted into rats to replace 8 mm of sciatic nerve. The implants were harvested after 2 months and analyzed with immunohistochemistry and transmission electron microscopy. The regenerated nerve tissue displayed myelinated axons and Schwann cells that were similar to those in the native nerve. Electrical stimulation applied through the electrically conductive biodegradable polymers therefore enhanced neurite outgrowth in a current-dependent fashion. The conductive polymers also supported sciatic nerve regeneration in rats.

  17. Thermal and Electrical Investigation of Conductive Polylactic Acid Based Filaments

    Science.gov (United States)

    Dobre, R. A.; Marcu, A. E.; Drumea, A.; Vlădescu, M.

    2018-06-01

    Printed electronics gain momentum as the involved technologies become affordable. The ability to shape electrostatic dissipative materials in almost any form is useful. The idea to use a general-purpose 3D printer to manufacture the electrical interconnections for a circuit is very attractive. The advantage of using a 3D printed structure over other technologies are mainly the lower price, less requirements concerning storage and use conditions, and the capability to build thicker traces while maintaining flexibility. The main element allowing this to happen is a printing filament with conductive properties. The paper shows the experiments that were performed to determine the thermal and electrical properties of polylactic acid (PLA) based ESD dissipative filament. Quantitative results regarding the thermal behavior of the DC resistance and the variation of the equivalent parallel impedance model parameters (losses resistance, capacitance, impedance magnitude and phase angle) with frequency are shown.. Using these results, new applications like printed temperature sensors can be imagined.

  18. Fabrication of Extrinsically Conductive Silicone Rubbers with High Elasticity and Analysis of Their Mechanical and Electrical Characteristics

    Directory of Open Access Journals (Sweden)

    Anjum Saleem

    2010-08-01

    Full Text Available Conductive plastics are attracting more and more interest in electronics due to their light weight and inability to rust, which are common problems associated with metals. The field of conducting plastics is not new. Much work has been done to impart electrical conductivity to mechanically strong polymers such as polypropylene, polycarbonate and epoxies, etc. However there is a need to fabricate more flexible and elastic conductive polymers such as conducting silicone rubbers for use in various applications. In this work silicone rubbers reinforced with conductive fillers have been fabricated for use as sensors in textiles to detect the resistance change produced by stretching or relaxing. The variations of electrical resistance have been investigated by stretching and releasing the strands of conductive rubbers as a function of time. Two types of silicone rubbers—addition cured and condensation cured—were compounded with different electrically conductive fillers, among which carbon fibers have shown the best results. The carbon fibers improved the electrical conductance of the rubbers, even in very low weight percentages. The increasing concentration of fillers decreases the elasticity of the rubber. In order to keep the original properties of silicones, the filler concentration was kept as low as possible to produce a significantly detectable signal. The fabricated compounds were analyzed for their mechanical properties by stress strain curves. Such materials find their applications in electronics, antistatic applications, sports and the automotive industry where they can be used as deformation sensors.

  19. Electrical and mechanical properties of asphalt concrete containing conductive fibers and fillers

    NARCIS (Netherlands)

    Wang, H.; Yang, Jun; Liao, Hui; Chen, Xianhua

    2016-01-01

    Electrically conductive asphalt concrete has the potential to satisfy multifunctional applications. Designing such asphalt concrete needs to balance the electrical and mechanical performance of asphalt concrete. The objective of this study is to design electrically conductive asphalt concrete

  20. Electrical conductivity of uranium-antimony oxide catalysts

    International Nuclear Information System (INIS)

    Golunski, S.E.; Nevell, T.G.; Hucknall, D.J.

    1985-01-01

    The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO 5 have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb 3 O 10 together with small proportions of Sb 2 O 4 and USbO 5 ) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO 5 . Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO 5 in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation. (author)

  1. Electrical conductivity of uranium-antimony oxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Golunski, S.E.; Nevell, T.G. (Portsmouth Polytechnic (UK)); Hucknall, D.J. (Southampton Univ. (UK). Dept. of Chemistry)

    1985-05-01

    The relative ionic and electronic contributions to the electrical conductivity of a uranium-antimony oxide catalyst and of USbO/sub 5/ have been determined from measurements of a.c. and d.c. conductance. Under inert atmospheres (390 to 775 K) conduction in the catalyst (predominantly USb/sub 3/O/sub 10/ together with small proportions of Sb/sub 2/O/sub 4/ and USbO/sub 5/) is associated with both electronic and effectively charged atomic point defects. Only electronic conduction occurs in USbO/sub 5/. Under oxygen (10 to 70 kPa, 493 to 682 K) both materials are n-type semiconductors at higher temperatures, but at lower temperatures semiconducting behaviour varies with the pressure of oxygen. Heating USbO/sub 5/ in oxygen induces an ionic contribution to conductivity. Ionic conduction in the catalyst is eliminated by heating in hydrogen or propene at 470 K but is restored by heating in oxygen. It is suggested that both charged oxygen vacancies and interstitial oxide ions are involved in interactions of gaseous components with uranium-antimony oxides. With alkenes, interstitial oxide ions give rise to the products of selective partial oxidation.

  2. Enhanced electrical conductivity in Xe ion irradiated CNT based transparent conducting electrode on PET substrate

    Science.gov (United States)

    Surbhi; Sharma, Vikas; Singh, Satyavir; Garg, Priyanka; Asokan, K.; Sachdev, Kanupriya

    2018-02-01

    An investigation of MWCNT-based hybrid electrode films with improved electrical conductivity after Xe ion irradiation is reported. A multilayer hybrid structure of Ag-MWCNT layer embedded in between two ZnO layers was fabricated and evaluated, pre and post 100 keV Xe ion irradiation, for their performance as Transparent Conducting Electrode in terms of their optical and electrical properties. X-ray diffraction pattern exhibits highly c-axis oriented ZnO films with a small variation in lattice parameters with an increase in ion fluence. There is no significant change in the surface roughness of these films. Raman spectra were used to confirm the presence of CNT. The pristine multilayer films exhibit an average transmittance of ˜70% in the entire visible region and the transmittance increases with Xe ion fluence. A significant enhancement in electrical conductivity post-Xe ion irradiation viz from 1.14 × 10-7 Ω-1 cm-1 (pristine) to 7.04 × 103 Ω-1 cm-1 is seen which is due to the high connectivity in the top layer with Ag-CNT hybrid layer facilitating the smooth transfer of electrons.

  3. Dielectric behavior and ac electrical conductivity of nanocrystalline nickel aluminate

    International Nuclear Information System (INIS)

    Kurien, Siby; Mathew, Jose; Sebastian, Shajo; Potty, S.N.; George, K.C.

    2006-01-01

    Nanocrystalline nickel aluminate was prepared by chemical co-precipitation, and nanoparticles having different particle size were obtained by annealing the precursor at different temperatures. The TG/DTA measurements showed thermal decomposition was a three-step process with crystallisation of the spinel phase started at a temperature 420 deg. C. The X-ray diffraction analysis confirmed that the specimen began to crystallise on annealing above 420 deg. C and became almost crystalline at about 900 deg. C. The particle sizes were calculated from XRD. Dielectric properties of nickel aluminate were studied as a function of the frequency of the applied ac signal at different temperatures. It was seen the real dielectric constant ε', and dielectric loss tan δ decreased with frequency of applied field while the ac conductivity increased as the frequency of the applied field increased. The dielectric relaxation mechanism is explained by considering nanostructured NiAl 2 O 4 as a carrier-dominated dielectric with high density of hopping charge carriers. The variation of ε' with different particle size depends on several interfacial region parameters, which change with the average particle size

  4. Anelastic spherical dynamos with radially variable electrical conductivity

    Science.gov (United States)

    Dietrich, W.; Jones, C. A.

    2018-05-01

    A series of numerical simulations of the dynamo process operating inside gas giant planets has been performed. We use an anelastic, fully nonlinear, three-dimensional, benchmarked MHD code to evolve the flow, entropy and magnetic field. Our models take into account the varying electrical conductivity, high in the ionised metallic hydrogen region, low in the molecular outer region. Our suite of electrical conductivity profiles ranges from Jupiter-like, where the outer hydrodynamic region is quite thin, to Saturn-like, where there is a thick non-conducting shell. The rapid rotation leads to the formation of two distinct dynamical regimes which are separated by a magnetic tangent cylinder - mTC. Outside the mTC there are strong zonal flows, where Reynolds stress balances turbulent viscosity, but inside the mTC Lorentz force reduces the zonal flow. The dynamic interaction between both regions induces meridional circulation. We find a rich diversity of magnetic field morphologies. There are Jupiter-like steady dipolar fields, and a belt of quadrupolar dominated dynamos spanning the range of models between Jupiter-like and Saturn-like conductivity profiles. This diversity may be linked to the appearance of reversed sign helicity in the metallic regions of our dynamos. With Saturn-like conductivity profiles we find models with dipolar magnetic fields, whose axisymmetric components resemble those of Saturn, and which oscillate on a very long time-scale. However, the non-axisymmetric field components of our models are at least ten times larger than those of Saturn, possibly due to the absence of any stably stratified layer.

  5. Increased electrical conductivity of peptides through annealing process

    Directory of Open Access Journals (Sweden)

    Seok Daniel Namgung

    2017-08-01

    Full Text Available Biocompatible biologically occurring polymer is suggested as a component of human implantable devices since conventional inorganic materials are apt to trigger inflammation and toxicity problem within human body. Peptides consisting of aromatic amino acid, tyrosine, are chosen, and enhancement on electrical conductivity is studied. Annealing process gives rise to the decrease on resistivity of the peptide films and the growth of the carrier concentration is a plausible reason for such a decrease on resistivity. The annealed peptides are further applied to an active layer of field effect transistor, in which low on/off current ratio (∼10 is obtained.

  6. Investigation of conduction and relaxation phenomena in BaZrxTi1-xO3 (x=0.05) by impedance spectroscopy

    Science.gov (United States)

    Mahajan, Sandeep; Haridas, Divya; Ali, S. T.; Munirathnam, N. R.; Sreenivas, K.; Thakur, O. P.; Prakash, Chandra

    2014-10-01

    In present study we have prepared ferroelectric BaZrxTi1-xO3 (x=0.05) ceramic by conventional solid state reaction route and studied its electrical properties as a function of temperature and frequency. X-ray diffraction (XRD) analysis shows single-phase formation of the compound with orthorhombic crystal structure at room temperature. Impedance and electric modulus spectroscopy analysis in the frequency range of 40 Hz-1 MHz at high temperature (200-600 °C) suggests two relaxation processes with different time constant are involved which are attributed to bulk and grain boundary effects. Frequency dependent dielectric plot at different temperature shows normal variation with frequency while dielectric loss (tanδ) peak was found to obey an Arrhenius law with activation energy of 1.02 eV. The frequency-dependent AC conductivity data were also analyzed in a wide temperature range. In present work we have studied the role of grain and grain boundaries on the electrical behaviour of Zr-doped BaTiO3 and their dependence on temperature and frequency by complex impedance and modulus spectroscopy (CIS) technique in a wide frequency (40 Hz-1 MHz) and high temperature range.

  7. The bedrock electrical conductivity structure of Northern Ireland

    Science.gov (United States)

    Beamish, David

    2013-08-01

    An airborne geophysical survey of the whole of Northern Ireland has provided over 4.8 M estimates of the bedrock conductivity over the wide range of geological formations present. This study investigates how such data can be used to provide additional knowledge in relation to existing digital geological map information. A by-product of the analysis is a simplification of the spatially aggregated information obtained in such surveys. The methodology used is a GIS-based attribution of the conductivity estimates using a lithological classification of the bedrock formations. A 1:250k geological classification of the data is performed leading to a 56 unit lithological and geostatistical analysis of the conductivity information. The central moments (medians) of the classified data are used to provide a new digital bedrock conductivity map of Northern Ireland with values ranging from 0.32 to 41.36 mS m-1. This baseline map of conductivities displays a strong correspondence with an existing 4 quadrant, chrono-geological description of Northern Ireland. Once defined, the baseline conductivity map allows departures from the norm to be assessed across each specific lithological unit. Bulk electrical conductivity is controlled by a number of petrophysical parameters and it is their variation that is assessed by the procedures employed. The igneous rocks are found to display the largest variability in conductivity values and many of the statistical distributions are multi-modal. A sequence of low-value modes in these data are associated with intrusives within volcanic complexes. These and much older Neoproterzoic rocks appear to represent very low porosity formations that may be the product of rapid cooling during emplacement. By way of contrast, extensive flood basalts (the Antrim lavas) record a well-defined and much higher median value (12.24 mS m-1) although they display complex spatial behaviour in detail. Sedimentary rocks appear to follow the broad behaviours anticipated

  8. Electrical conductivity of quasi-two-dimensional foams.

    Science.gov (United States)

    Yazhgur, Pavel; Honorez, Clément; Drenckhan, Wiebke; Langevin, Dominique; Salonen, Anniina

    2015-04-01

    Quasi-two-dimensional (quasi-2D) foams consist of monolayers of bubbles squeezed between two narrowly spaced plates. These simplified foams have served successfully in the past to shed light on numerous issues in foam physics. Here we consider the electrical conductivity of such model foams. We compare experiments to a model which we propose, and which successfully relates the structural and the conductive properties of the foam over the full range of the investigated liquid content. We show in particular that in the case of quasi-2D foams the liquid in the nodes needs to be taken into account even at low liquid content. We think that these results may provide different approaches for the characterization of foam properties and for the in situ characterization of the liquid content of foams in confining geometries, such as microfluidics.

  9. Effective holographic theories of momentum relaxation and violation of conductivity bound

    Energy Technology Data Exchange (ETDEWEB)

    Goutéraux, Blaise [Stanford Institute for Theoretical Physics, Department of Physics,Stanford University, Stanford, CA 94305-4060 (United States); APC, Université Paris 7, CNRS/IN2P3, CEA/IRFU, Obs. de Paris,Sorbonne Paris Cité, Bâtiment Condorcet, F-75205,Paris Cedex 13, France (UMR du CNRS 7164) (France); Kiritsis, Elias [APC, Université Paris 7, CNRS/IN2P3, CEA/IRFU, Obs. de Paris,Sorbonne Paris Cité, Bâtiment Condorcet, F-75205,Paris Cedex 13, France (UMR du CNRS 7164) (France); Crete Center for Theoretical Physics and I.P.P.,Department of Physics, University of Crete, 71003 Heraklion (Greece); Li, Wei-Jia [Crete Center for Theoretical Physics and I.P.P.,Department of Physics, University of Crete, 71003 Heraklion (Greece)

    2016-04-19

    We generalize current holographic models with homogeneous breaking of translation symmetry by incorporating higher derivative couplings, in the spirit of effective field theories. Focusing on charge transport, we specialize to two simple couplings between the charge and translation symmetry breaking sectors. We obtain analytical charged black brane solutions and compute their DC conductivity in terms of horizon data. We constrain the allowed values of the couplings and note that the DC conductivity can vanish at zero temperature for strong translation symmetry breaking, thus showing that in general there is no lower bound on the conductivity.

  10. Effective holographic theories of momentum relaxation and violation of conductivity bound

    International Nuclear Information System (INIS)

    Goutéraux, Blaise; Kiritsis, Elias; Li, Wei-Jia

    2016-01-01

    We generalize current holographic models with homogeneous breaking of translation symmetry by incorporating higher derivative couplings, in the spirit of effective field theories. Focusing on charge transport, we specialize to two simple couplings between the charge and translation symmetry breaking sectors. We obtain analytical charged black brane solutions and compute their DC conductivity in terms of horizon data. We constrain the allowed values of the couplings and note that the DC conductivity can vanish at zero temperature for strong translation symmetry breaking, thus showing that in general there is no lower bound on the conductivity.

  11. Apparent soil electrical conductivity in two different soil types

    Directory of Open Access Journals (Sweden)

    Wilker Nunes Medeiros

    Full Text Available ABSTRACT Mapping the apparent soil electrical conductivity (ECa has become important for the characterization of the soil variability in precision agriculture systems. Could the ECa be used to locate the soil sampling points for mapping the chemical and physical soil attributes? The objective of this work was to examine the relations between ECa and soil attributes in two fields presenting different soil textures. In each field, 50 sampling points were chosen using a path that presented a high variability of ECa obtained from a preliminary ECa map. At each sampling point, the ECa was measured in soil depths of 0-20, 0-40 and 0-60 cm. In addition, at each point, soil samples were collected for the determination of physical and chemical attributes in the laboratory. The ECa data obtained for different soil depths was very similar. A large number of significant correlations between ECa and the soil attributes were found. In the sandy clay loam texture field there was no correlation between ECa and organic matter or between ECa and soil clay and sand content. However, a significant positive correlation was shown for the remaining phosphorus. In the sandy loam texture field the ECa had a significant positive correlation with clay content and a significant negative correlation with sand content. The results suggest that the mapping of apparent soil electrical conductivity does not replace traditional soil sampling, however, it can be used as information to delimit regions in a field that have similar soil attributes.

  12. Density, viscosity and electrical conductivity of protic alkanolammonium ionic liquids.

    Science.gov (United States)

    Pinkert, André; Ang, Keng L; Marsh, Kenneth N; Pang, Shusheng

    2011-03-21

    Ionic liquids are molten salts with melting temperatures below the boiling point of water, and their qualification for applications in potential industrial processes does depend on their fundamental physical properties such as density, viscosity and electrical conductivity. This study aims to investigate the structure-property relationship of 15 ILs that are primarily composed of alkanolammonium cations and organic acid anions. The influence of both the nature and number of alkanol substituents on the cation and the nature of the anion on the densities, viscosities and electrical conductivities at ambient and elevated temperatures are discussed. Walden rule plots are used to estimate the ionic nature of these ionic liquids, and comparison with other studies reveals that most of the investigated ionic liquids show Walden rule values similar to many non-protic ionic liquids containing imidazolium, pyrrolidinium, tetraalkylammonium, or tetraalkylphosphonium cations. Comparison of literature data reveals major disagreements in the reported properties for the investigated ionic liquids. A detailed analysis of the reported experimental procedures suggests that inappropriate drying methods can account for some of the discrepancies. Furthermore, an example for the improved presentation of experimental data in scientific literature is presented.

  13. Patterns of gas and liquid reflux during transient lower oesophageal sphincter relaxation: a study using intraluminal electrical impedance

    OpenAIRE

    Sifrim, D; Silny, J; Holloway, R; Janssens, J

    1999-01-01

    Background—Belching has been proposed as a major mechanism underlying acid gastro-oesophageal reflux in normal subjects. However, the presence of oesophageal gas has not been measured directly but only inferred from manometry. 
Aims—To investigate, using intraluminal electrical impedance, the patterns of gas and liquid reflux during transient lower oesophageal sphincter (LOS) relaxations, the main mechanism of acid reflux in normal subjects. 
Methods—Impedance changes ass...

  14. Dependence of radiation electric conductivity on intensity of external electric field in polymeric dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Sichkar, V P; Tyutnev, A P; Vaisberg, S E [Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR)

    1975-10-01

    The radiational conductivity (Gsub(p)) at different electric field potentials (E) for a number of low- and high-density polymers was investigated. In a number of cases temperature variations were introduced. Measurements were carried out also under conditions of a single impulse of high-power radiation dose. A relationship was obtained between Gsub(p) and E.

  15. Interdiffusion and Spinodal Decomposition in Electrically Conducting Polymer Blends

    Directory of Open Access Journals (Sweden)

    Antti Takala

    2015-08-01

    Full Text Available The impact of phase morphology in electrically conducting polymer composites has become essential for the efficiency of the various functional applications, in which the continuity of the electroactive paths in multicomponent systems is essential. For instance in bulk heterojunction organic solar cells, where the light-induced electron transfer through photon absorption creating excitons (electron-hole pairs, the control of diffusion of the spatially localized excitons and their dissociation at the interface and the effective collection of holes and electrons, all depend on the surface area, domain sizes, and connectivity in these organic semiconductor blends. We have used a model semiconductor polymer blend with defined miscibility to investigate the phase separation kinetics and the formation of connected pathways. Temperature jump experiments were applied from a miscible region of semiconducting poly(alkylthiophene (PAT blends with ethylenevinylacetate-elastomers (EVA and the kinetics at the early stages of phase separation were evaluated in order to establish bicontinuous phase morphology via spinodal decomposition. The diffusion in the blend was followed by two methods: first during a miscible phase separating into two phases: from the measurement of the spinodal decomposition. Secondly the diffusion was measured by monitoring the interdiffusion of PAT film into the EVA film at elected temperatures and eventually compared the temperature dependent diffusion characteristics. With this first quantitative evaluation of the spinodal decomposition as well as the interdiffusion in conducting polymer blends, we show that a systematic control of the phase separation kinetics in a polymer blend with one of the components being electrically conducting polymer can be used to optimize the morphology.

  16. Acidosis slows electrical conduction through the atrio-ventricular node.

    Science.gov (United States)

    Nisbet, Ashley M; Burton, Francis L; Walker, Nicola L; Craig, Margaret A; Cheng, Hongwei; Hancox, Jules C; Orchard, Clive H; Smith, Godfrey L

    2014-01-01

    Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.

  17. Acidosis slows electrical conduction through the atrio-ventricular node

    Directory of Open Access Journals (Sweden)

    Ashley Muir Nisbet

    2014-06-01

    Full Text Available Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN. In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode’s solution (20% CO2, pH 6.7 increased the time of earliest activation (Tact from 100.5+7.9 to 166.1+7.2ms (n=8 at a pacing cycle length (PCL of 300ms (37oC. Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150ms PCL, Tact was prolonged from 131.0+5.2 to 174.9+16.3ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode’s solutions at pH 7.4 (control, 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH interval, the effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.

  18. Low frequency ac conduction and dielectric relaxation in poly(N ...

    Indian Academy of Sciences (India)

    Unknown

    polymer chain in the form of bands analogous to that of a semiconductor and the ... these materials a model has been proposed which suggests the application of two .... values is almost equal to dc conductivity value while in high frequency ...

  19. Silver Flakes and Silver Dendrites for Hybrid Electrically Conductive Adhesives with Enhanced Conductivity

    Science.gov (United States)

    Ma, Hongru; Li, Zhuo; Tian, Xun; Yan, Shaocun; Li, Zhe; Guo, Xuhong; Ma, Yanqing; Ma, Lei

    2018-03-01

    Silver dendrites were prepared by a facile replacement reaction between silver nitrate and zinc microparticles of 20 μm in size. The influence of reactant molar ratio, reaction solution volume, silver nitrate concentration, and reaction time on the morphology of dendrites was investigated systematically. It was found that uniform tree-like silver structures are synthesized under the optimal conditions. Their structure can be described as a trunk, symmetrical branches, and leaves, which length scales of 5-10, 1-2 μm, and 100-300 nm, respectively. All features were systematically characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and x-ray powder diffraction. A hybrid fillers system using silver flakes and dendrites as electrically conductive adhesives (ECAs) exhibited excellent overall performance. This good conductivity can be attributed mainly to the synergy between the silver microflakes (5-20 μm sized irregular sheet structures) and dendrites, allowing more conductive pathways to be formed between the fillers. In order to further optimize the overall electrical conductivity, various mixtures of silver microflakes and silver dendrites were tested in ECAs, with results indicating that the highest conductivity was shown when the amounts of silver microflakes, silver dendrites and the polymer matrix were 69.4 wt.% (20.82 vol.%), 0.6 wt.% (0.18 vol.%), and 30.0 wt.% (79.00 vol.%), respectively. The corresponding mass ratio of silver flakes to silver dendrites was 347:3. The resistivity of ECAs reached as low as 1.7 × 10-4 Ω cm.

  20. Imaging in electrically conductive porous media without frequency encoding.

    Science.gov (United States)

    Lehmann-Horn, J A; Walbrecker, J O

    2012-07-01

    Understanding multi-phase fluid flow and transport processes under various pressure, temperature, and salinity conditions is a key feature in many remote monitoring applications, such as long-term storage of carbon dioxide (CO(2)) or nuclear waste in geological formations. We propose a low-field NMR tomographic method to non-invasively image the water-content distribution in electrically conductive formations in relatively large-scale experiments (∼1 m(3) sample volumes). Operating in the weak magnetic field of Earth entails low Larmor frequencies at which electromagnetic fields can penetrate electrically conductive material. The low signal strengths associated with NMR in Earth's field are enhanced by pre-polarization before signal recording. To localize the origin of the NMR signal in the sample region we do not employ magnetic field gradients, as is done in conventional NMR imaging, because they can be difficult to control in the large sample volumes that we are concerned with, and may be biased by magnetic materials in the sample. Instead, we utilize the spatially dependent inhomogeneity of fields generated by surface coils that are installed around the sample volume. This relatively simple setup makes the instrument inexpensive and mobile (it can be potentially installed in remote locations outside of a laboratory), while allowing spatial resolution of the order of 10 cm. We demonstrate the general feasibility of our approach in a simulated CO(2) injection experiment, where we locate and quantify the drop in water content following gas injection into a water-saturated cylindrical sample of 0.45 m radius and 0.9 m height. Our setup comprises four surface coils and an array consisting of three volume coils surrounding the sample. The proposed tomographic NMR methodology provides a more direct estimate of fluid content and properties than can be achieved with acoustic or electromagnetic methods alone. Therefore, we expect that our proposed method is relevant

  1. Magneto-acousto-electrical Measurement Based Electrical Conductivity Reconstruction for Tissues.

    Science.gov (United States)

    Zhou, Yan; Ma, Qingyu; Guo, Gepu; Tu, Juan; Zhang, Dong

    2018-05-01

    Based on the interaction of ultrasonic excitation and magnetoelectrical induction, magneto-acousto-electrical (MAE) technology was demonstrated to have the capability of differentiating conductivity variations along the acoustic transmission. By applying the characteristics of the MAE voltage, a simplified algorithm of MAE measurement based conductivity reconstruction was developed. With the analyses of acoustic vibration, ultrasound propagation, Hall effect, and magnetoelectrical induction, theoretical and experimental studies of MAE measurement and conductivity reconstruction were performed. The formula of MAE voltage was derived and simplified for the transducer with strong directivity. MAE voltage was simulated for a three-layer gel phantom and the conductivity distribution was reconstructed using the modified Wiener inverse filter and Hilbert transform, which was also verified by experimental measurements. The experimental results are basically consistent with the simulations, and demonstrate that the wave packets of MAE voltage are generated at tissue interfaces with the amplitudes and vibration polarities representing the values and directions of conductivity variations. With the proposed algorithm, the amplitude and polarity of conductivity gradient can be restored and the conductivity distribution can also be reconstructed accurately. The favorable results demonstrate the feasibility of accurate conductivity reconstruction with improved spatial resolution using MAE measurement for tissues with conductivity variations, especially suitable for nondispersive tissues with abrupt conductivity changes. This study demonstrates that the MAE measurement based conductivity reconstruction algorithm can be applied as a new strategy for nondestructive real-time monitoring of conductivity variations in biomedical engineering.

  2. Relaxation dynamics of the conductive processes for PbNb2O6 ferroelectric ceramics in the frequency and time domain

    International Nuclear Information System (INIS)

    Gonzalez, R L; Leyet, Y; Guerrero, F; Guerra, J de Los S; Venet, M; Eiras, J A

    2007-01-01

    The relaxation dynamics of the conductive process present in PbNb 2 O 6 piezoelectric ceramics was investigated. A relaxation function in the time domain, Φ(t), was found from the frequency dependence of the dielectric modulus (imaginary component, M'') by using a relaxation function in the frequency domain, F*(ω). The best relaxation function, F*(ω), was found to be a Cole-Cole distribution function, in which relaxation characteristic parameters, such as α and τ CC , are involved. On the other hand, the relaxation function, Φ(t), obtained by the time domain method, was found to be a Kohlrausch-Williams-Watts (KWW) function type. The thermal evolution of the characteristics parameters of the KWW function (β and τ*) was analysed. The values of the activation energy (E a ), obtained in the whole investigated temperature interval, suggest the existence of a relaxation mechanism (a conductive process), which may be interpreted by an ion hopping between neighbouring sites within the crystalline lattice. The results are corroborated with the formalism of the AC conductivity

  3. Control of electrical conduction in DNA using hole doping

    Science.gov (United States)

    Lee, Hea-Yeon; Taniguchi, Masateru; Yoo, K. H.; Otsuka, Youichi; Tanaka, Hidekazu; Kawai, Tomoji

    2002-03-01

    Control of electrical conduction in DNA using hole doping H.Y.Lee1, M.Taniguchi1, K.H.Yoo2, Y.Otsuka1 H.Tanaka1 and T.Kawai1 1The Institute of Scientific and Industrial Research(ISIR), Osaka University, Osaka, Japan. 2Department of Physics, Younsei University, Seoul, Korea Possible applications of DNA molecules in electronic devices and biosensors were suggested almost ten years ago A DNA structure containing a single type of base pair appears to be a good candidate for conduction along the \\x81E-electron clouds of the stacked bases. There have been lots of investigations on conduction mechanisms of the DNA molecules. However, it is not still clear whether the observed conductions of some DNA molecules come from motions of either ionic charges or other carriers. Although the basic mechanism for DNA-mediated charge transport should be understood for electronic applications, there have been divergent reports on its nature. And I will be present the research for the charge carrier conduction of DNA film under oxygen and iodine gas by using 10¡V100 nm gap. The doping studies using oxygen and iodine gas can provide a definite answer for the carrier conduction mechanism and also a possible method to control the carrier concentration in DNA molecules. Using oxygen and iodine adsorption experiments on the poly (dG)-poly (dC) DNA molecules, we will show that their conductance becomes increased easily by several orders of magnitudes due to the hole doping, which is a characteristic behavior of a p-type semiconductor. On the other hand, we will also show that the poly (dA) - poly (dT) DNA molecules behave as an n-type semiconductor. Our works indicate that the concentration and the type of carriers in the DNA molecules could be controlled using proper doping methods. We expect that this would be a major breakthrough in DNA-based nano-electronics, similar to the fact that the doped conductive has polyacetylene opened up a new field of electronics with exciting implications

  4. Electrically and Thermally Conducting Nanocomposites for Electronic Applications

    Directory of Open Access Journals (Sweden)

    Daryl Santos

    2010-02-01

    Full Text Available Nanocomposites made up of polymer matrices and carbon nanotubes are a class of advanced materials with great application potential in electronics packaging. Nanocomposites with carbon nanotubes as fillers have been designed with the aim of exploiting the high thermal, electrical and mechanical properties characteristic of carbon nanotubes. Heat dissipation in electronic devices requires interface materials with high thermal conductivity. Here, current developments and challenges in the application of nanotubes as fillers in polymer matrices are explored. The blending together of nanotubes and polymers result in what are known as nanocomposites. Among the most pressing current issues related to nanocomposite fabrication are (i dispersion of carbon nanotubes in the polymer host, (ii carbon nanotube-polymer interaction and the nature of the interface, and (iii alignment of carbon nanotubes in a polymer matrix. These issues are believed to be directly related to the electrical and thermal performance of nanocomposites. The recent progress in the fabrication of nanocomposites with carbon nanotubes as fillers and their potential application in electronics packaging as thermal interface materials is also reported.

  5. Polyaniline-CuO hybrid nanocomposite with enhanced electrical conductivity

    Science.gov (United States)

    de Souza, Vânia S.; da Frota, Hidembergue O.; Sanches, Edgar A.

    2018-02-01

    A hybrid nanocomposite based on a polymer matrix constituted of Polyaniline Emeraldine-salt form (PANI-ES) reinforced by copper oxide II (CuO) particles was obtained by in situ polymerization. Structural, morphological and electrical properties of the pure materials and nanocomposite form were investigated. The presence of CuO particles in the nanocomposite material affected the natural alignment of the polymer chains. XRD technique allowed the visualization of the polymer amorphization in the nanocomposite form, suggesting an interaction between both phases. The FTIR spectra confirmed this molecular interaction due to the blue shift of the characteristic absorption peaks of PANI-ES in the nanocomposite form. SEM images revealed that the polymer nanofiber morphology was no longer observed in the nanocomposite. The CuO spherical particles are randomly dispersed in the polymer matrix. The density functional theory plus the Coulomb interaction method revealed a charge transfer from PANI to CuO slab. Moreover, the density of states (DOS) has revealed that the nanocomposite behaves as a metal. In agreement, the electrical conductivity showed an increase of 60% in the nanocomposite material.

  6. Electrical conductance of carbon nanotubes with misaligned ends

    Energy Technology Data Exchange (ETDEWEB)

    Pantano, Antonio, E-mail: antonio.pantano@unipa.it; Muratore, Giuseppe; Montinaro, Nicola [Universita degli Studi di Palermo, Dipartimento di Ingegneria Chimica, Gestionale, Informatica e Meccanica (Italy)

    2013-09-15

    During a manufacturing process, when a straight carbon nanotube is placed on a substrate, e.g., production of transistors, its two ends are often misaligned. In this study, we investigate the effects of multiwall carbon nanotubes' (MWCNTs) outer diameter and chirality on the change in conductance due to misalignment of the two ends. The length of the studied MWCNTs was 120 nm, while the diameters ranged between 4 and 7 nm. A mixed finite element-tight-binding approach was carefully designed to realize reduction in computational time by orders of magnitude in calculating the deformation-induced changes in the electrical transport properties of the nanotubes. Numerical results suggest that armchair MWCNTs of small diameter should work better if used as conductors, while zigzag MWCNTs of large diameter are more suitable for building sensors.Graphical Abstract.

  7. About the free electron model in electric conduction of metals

    International Nuclear Information System (INIS)

    Hoffmann, C.

    1991-01-01

    In the model proposed by Drude to describe, among others, the electric conduction in metals, it is supposed that electrons move freely in the material with a time interval between encounters T and a probability distribution g(t). The name, 'electron pause time', will be assigned to the time T with that probability distribution. The calculations made by Drude turned out to be erroneous. The error can be corrected observing that the random variable 'pause time' appearing in this intuitive idea is not the previously defined random variable T, 'electron pause time', but another random variable S, which will be called 'observed pause time' whose probability density is Csg(s), where C is a normalization constant. With this distribution, the characteristics of the distribution, q(u), of the wait time can be obtained. (Author) [es

  8. Polymeric salt bridges for conducting electric current in microfluidic devices

    Science.gov (United States)

    Shepodd, Timothy J [Livermore, CA; Tichenor, Mark S [San Diego, CA; Artau, Alexander [Humacao, PR

    2009-11-17

    A "cast-in-place" monolithic microporous polymer salt bridge for conducting electrical current in microfluidic devices, and methods for manufacture thereof is disclosed. Polymeric salt bridges are formed in place in capillaries or microchannels. Formulations are prepared with monomer, suitable cross-linkers, solvent, and a thermal or radiation responsive initiator. The formulation is placed in a desired location and then suitable radiation such as UV light is used to polymerize the salt bridge within a desired structural location. Embodiments are provided wherein the polymeric salt bridges have sufficient porosity to allow ionic migration without bulk flow of solvents therethrough. The salt bridges form barriers that seal against fluid pressures in excess of 5000 pounds per square inch. The salt bridges can be formulated for carriage of suitable amperage at a desired voltage, and thus microfluidic devices using such salt bridges can be specifically constructed to meet selected analytical requirements.

  9. Genetic aspects of milk electrical conductivity in Italian Brown cattle

    Directory of Open Access Journals (Sweden)

    Martino Cassandro

    2010-01-01

    Full Text Available Electrical conductivity (EC of milk is defined as an indicator of the udder health. The EC is a low cost and easy recordable information in dairy herds with automatic milking systems. The heritability of EC showed to be higher than somatic cell count and for this reason might be an useful trait for indirect selection for mastitis resistance. The heritability for EC in Italian Brown cattle was equal to 0.23. Therefore, EC could be useful not only for dairy cows management but also for selection of dairy cows. The high correlation between breeding values for SCC and EC is promising in order for improving mastitis resistance and functional ability of dairy cows.

  10. Thermal effects of electrically conductive deposits in melter

    International Nuclear Information System (INIS)

    Choi, I.G.; Bickford, D.F.; Carter, J.T.

    1992-01-01

    The radioactive waste processed by the Defense Waste Processing Facility melter at the Savannah river Site contains noble metal fission-products. Operation of waste-glass melters treating commercial power reactor wastes indicates that accumulation of noble metals on melter floors can lead to distortion of electric heating patterns, loss of power, and possible electrode damage. Changes in melter geometry have been developed in Japan and Germany to minimize these effects. The two existing melters for the US Department of Energy's Defense Waste Processing Facility were designed in 1982, before this effect was known or had been characterized. Modeling and pilot scale tests are being conducted in the Integrated DWPF melter system to determine if the effect is significant for melters processing defense wastes, and if the effect can be diagnosed and corrected without significant damage or changes to the melter design. This document provides a discussion of these tests

  11. Electrical conductivity and viscosity of borosilicate glasses and melts

    DEFF Research Database (Denmark)

    Ehrt, Doris; Keding, Ralf

    2009-01-01

    , 0 to 62·5 mol% B2O3, and 25 to 85 mol% SiO2. The glass samples were characterised by different methods. Refractive indices, density and thermal expansion were measured. Phase separation effects were investigated by electron microscopy. The electrical conductivity of glasses and melts were determined......Simple sodium borosilicate and silicate glasses were melted on a very large scale (35 l Pt crucible) to prepare model glasses of optical quality in order to investigate various properties depending on their structure. The composition of the glass samples varied in a wide range: 3 to 33·3 mol% Na2O...... by impedance measurements in a wide temperature range (250 to 1450°C). The activation energies were calculated by Arrhenius plots in various temperature regions: below the glass transition temperature, Tg, above the melting point, Tl, and between Tg and Tl. Viscosity measurements were carried out...

  12. Seed-borne pathogens and electrical conductivity of soybean seeds

    Directory of Open Access Journals (Sweden)

    Adriana Luiza Wain-Tassi

    2012-02-01

    Full Text Available Adequate procedures to evaluate seed vigor are important. Regarding the electrical conductivity test (EC, the interference in the test results caused by seed-borne pathogens has not been clarified. This research was carried out to study the influence of Phomopsis sojae (Leh. and Colletotrichum dematium (Pers. ex Fr. Grove var. truncata (Schw. Arx. fungi on EC results. Soybean seeds (Glycine max L. were inoculated with those fungi using potato, agar and dextrose (PDA medium with manitol (-1.0 MPa and incubated for 20 h at 25 °C. The colony diameter, index of mycelial growth, seed water content, occurrence of seed-borne pathogens, physiological potential of the seeds, measured by germination and vigor tests (seed germination index, cold test, accelerated aging and electrical conductivity, and seedling field emergence were determined. The contents of K+, Ca2+, and Mg2+ in the seed and in the soaking solution were also determined. A complete 2 × 4 factorial design with two seed sizes (5.5 and 6.5 mm and four treatments (control, seeds incubated without fungi, seeds incubated with Phomopsis and seeds incubated with Colletotrichum were used with eight (5.5 mm large seeds and six (6.5 mm large seeds replications. All seeds submitted to PDA medium had their germination reduced in comparison to the control seeds. This reduction was also observed when seed vigor and leached ions were considered. The presence of Phomopsis sojae fungus in soybean seed samples submitted to the EC test may be the cause of misleading results.

  13. Electric Conductivity and Dielectric-Breakdown Behavior for Polyurethane Magnetic Elastomers.

    Science.gov (United States)

    Sasaki, Shuhei; Tsujiei, Yuri; Kawai, Mika; Mitsumata, Tetsu

    2017-02-23

    The electric-voltage dependence of the electric conductivity for cross-linked and un-cross-linked magnetic elastomers was measured at various magnetic fields, and the effect of cross-linking on the electric conductivity and the dielectric-breakdown behavior was investigated. The electric conductivity for un-cross-linked elastomers at low voltages was independent of magnetic fields and the volume fraction of magnetic particles, indicating the electric conduction in the polyurethane matrix. At high voltages, the electric conductivity increased with the magnetic field, showing the electric conduction via chains of magnetic particles. On the other hand, the electric conductivity at low voltages for cross-linked elastomers with volume fractions below 0.06 was independent of the magnetic field, suggesting the electric conduction in the polyurethane matrix. At volume fractions above 0.14, the electric conductivity increased with the magnetic field, suggesting the electric conduction via chains of magnetic particles. At high voltages, the electric conductivity for cross-linked elastomers with a volume fraction of 0.02 was independent of the magnetic field, indicating the electric conduction through the polyurethane matrix. At volume fractions above 0.06, the electric conductivity suddenly increased at a critical voltage, exhibiting the dielectric breakdown at the bound layer of magnetic particles and/or the discontinuous part between chains.

  14. Development of Tailorable Electrically Conductive Thermal Control Material Systems

    Science.gov (United States)

    Deshpande, M. S.; Harada, Y.

    1997-01-01

    The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and have been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties as well as mechanical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has added to already existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The objective of this program was to develop two types of passive electrically conductive TCMS. The first was a highly absorbing/emitting black surface and the second was a low (alpha(sub s)/epsilon(sub N)) type white surface. The surface resistance goals for the black absorber was 10(exp 4) to 10(exp 9) Omega/square, and for the white surfaces it was 10(exp 6) to 10(exp 10) Omega/square. Several material system concepts were suggested and evaluated for space environment stability and electrical performance characterization. Our efforts in designing and evaluating these material systems have resulted in several developments. New concepts, pigments and binders have been developed to provide new engineering quality TCMS. Some of these have already found application on space hardware, some are waiting to be recognized by thermal designers, and some require further detailed studies to become state-of-the-art for future space hardware and space structures. Our studies on baseline state-of-the-art materials and

  15. Impact of electrical conductivity on acid hydrolysis of guar gum under induced electric field.

    Science.gov (United States)

    Li, Dandan; Zhang, Yao; Yang, Na; Jin, Zhengyu; Xu, Xueming

    2018-09-01

    This study aimed to improve induced electric field (IEF)-assisted hydrolysis of polysaccharide by controlling electrical conductivity. As the conductivity of reaction medium was increased, the energy efficiency of IEF was increased because of deceased impedance, as well as enhanced output voltage and temperature, thus the hydrolysis of guar gum (GG) was accelerated under IEF. Changes in weight-average molecular weight (Mw) suggested that IEF-assisted hydrolysis of GG could be described by the first-order kinetics 1/Mw ∝ kt, with the rate constant (k), varying directly with the medium conductivity. Although IEF-assisted hydrolysis largely disrupted the morphological structure of GG, it had no impact on the chemical structure. In comparison to native GG, the steady shear viscosity of hydrolyzed GG dramatically declined while the thermal stability slightly decreased. This study extended the knowledge of electrical conductivity upon IEF-assisted acid hydrolysis of GG and might contribute to a better utilization of IEF for polysaccharide modification. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. Investigation of electric conductivity, viscosity and density of LiBF4-1,3-dioxolane system in homogeneity region

    International Nuclear Information System (INIS)

    Plakhotnik, V.N.; Tovmash, N.F.; Mishustin, A.N.; Dam'e, V.N.

    1987-01-01

    Solutions of lithium tetrafluoborate in 1,3-dioxolane (DOL) in temperature range and concentrations limiting the homogeneity region from the side of salt crystallization and formation of polymer structures from -30 deg to +25 deg and from 10 -6 to 1.4 mol/l. are investigated using methods of conductometry, densimetry, viscosimetry and by measuring time of spinlattice 7 Li nuclei relaxation. The dissociation constant of LiBF 4 in DOL (pK D =4.9±0.2 at 25 deg) is determined. Comparison with systems based on 1,2-dimethoxyethane and tetrahydrofurane studied earlier is carried out. Suppositions concerning considerable contribution of ion molecular structures with participation of salt ions and solvent molecules to electric conductivity are stated, and it agrees with the data on measurements of velocities of spin-lattice relaxation of 7 Li nuclei

  17. Electrical conductivity in tokamaks and extended neoclassical theory

    International Nuclear Information System (INIS)

    Segre, S.E.; Zanza, V.

    1992-01-01

    The electrical conductivity measurements reported from various tokamaks (D-III, PLT, TEXT, ASDEX, JT-60, TEXTOR, JET, TFTR) and compared with the usual neoclassical theory are here also compared with the extended neoclassical theory where the electron-electron collision rate is anomalous while the electron-ion collision rate remains Coulombian. It is found that, out of the 14 experiments considered, three are consistent with both the neoclassical and the extended neoclassical theories, four are consistent only with the extended neoclassical theory, and four are consistent with the neoclassical theory and also, within the experimental errors, not inconsistent with the extended neoclassical theory; the remaining three experiments appear to be incompatible with both theories. It is concluded that the extended neoclassical theory is in better agreement with conductivity experiments than the conventional neoclassical theory and, indeed, the extended theory is a serious candidate for explaining tokamak behaviour, since it accommodates naturally an anomalous electron thermal transport, which the conventional neoclassical theory is unable to do. (author). 31 refs, 1 fig

  18. The size of Jupiter's electrically conducting fluid core

    International Nuclear Information System (INIS)

    Hide, R.; Malin, S.R.C.

    1979-01-01

    When the magnetic field of a planet is due to hydromagnetic dynamo action in an electrically conducting fluid core surrounded by a poorly conducting mantle it is possible in principle to determine the radius rsub(c) of the core from determinations of secular changes in the magnetic field B in the accessible region above the surface of the planet, mean radius rsub(s) (> = rsub(c)). A preliminary study is described in which the magnetic field measurements made in December 1973 and December 1974 when the Pioneer 10 and 11 fly-by space probes encountered Jupiter have been analysed. It was expected that over such a short time interval any true secular changes would be masked by errors and the corresponding estimates of rsub(c)/rsub(s) highly implausible or even physically impossible, but this turns out not to be the case. Taken at their face value the apparent secular changes in the dipole and quadrupole components of Jupiter's magnetic field imply that rsub(c)/rsub(s) is close to 0.7. Somewhat higher values of rsub(c)/rsub(s) are found when contributions from the octupole component are also included. (UK)

  19. Multivariate analysis of electrical impedance spectra for relaxed and contracted skeletal muscle

    International Nuclear Information System (INIS)

    Zagar, T; Krizaj, D

    2008-01-01

    Four-electrode impedance spectra of relaxed and contracted muscle biceps brachii were analyzed in an adult human subject over the frequency range from 300 Hz to 75 kHz. A feasibility of the principal component analysis of bioimpedance measurement for the evaluation of skeletal muscle contractile state was examined. The principal components score plots show a data grouping of the impedance spectra from the two muscle groups. The classification was performed using a soft independent modeling of class analogy (SIMCA) method. The data set comprised 32 samples (16 samples of contracted muscle and 16 samples of relaxed muscle). The leave-one-out test of the classification yields about 80% of correctly classified samples (11 samples for contracted and 15 samples for relaxed muscle)

  20. Investigation of conduction and relaxation phenomena in BaZrxTi1−xO3 (x=0.05) by impedance spectroscopy

    International Nuclear Information System (INIS)

    Mahajan, Sandeep; Haridas, Divya; Ali, S.T.; Munirathnam, N.R.; Sreenivas, K.; Thakur, O.P.; Prakash, Chandra

    2014-01-01

    In present study we have prepared ferroelectric BaZr x Ti 1−x O 3 (x=0.05) ceramic by conventional solid state reaction route and studied its electrical properties as a function of temperature and frequency. X-ray diffraction (XRD) analysis shows single-phase formation of the compound with orthorhombic crystal structure at room temperature. Impedance and electric modulus spectroscopy analysis in the frequency range of 40 Hz–1 MHz at high temperature (200–600 °C) suggests two relaxation processes with different time constant are involved which are attributed to bulk and grain boundary effects. Frequency dependent dielectric plot at different temperature shows normal variation with frequency while dielectric loss (tanδ) peak was found to obey an Arrhenius law with activation energy of 1.02 eV. The frequency-dependent AC conductivity data were also analyzed in a wide temperature range. - Graphical abstract: The electrical properties which give electrical microstructure that correlates to its ceramic microstructure are less studied for BZT. Various parameters such as grain, grain boundary and electrode/interface that affect the electrical properties in ceramics. The charge transport can be attributed to the charge displacement, dipole reorientation and space charge formation. In present work we have studied the role of grain and grain boundaries on the electrical behaviour of Zr-doped BaTiO 3 and their dependence on temperature and frequency by complex impedance and modulus spectroscopy (CIS) technique in a wide frequency (40 Hz–1 MHz) and high temperature range. - Highlights: • BaZr x Ti 1−x O 3 (x=0.05) ceramic by conventional solid state reaction route. • CIS used to study the material behaviour in wide range of frequency and temperature. • tanδ peak was found to obey an Arrhenius law with activation energy of 1.02 eV. • A parallel combination of RC circuit found for grain and grain boundaries

  1. Electrical conductivity studies of nanocrystalline lanthanum silicate synthesized by sol-gel route

    International Nuclear Information System (INIS)

    Nallamuthu, N.; Prakash, I.; Satyanarayana, N.; Venkateswarlu, M.

    2011-01-01

    Research highlights: → Nanocrystalline La 10 Si 6 O 27 material was synthesized by sol-gel method. → TG/DTA curves predicted the thermal behavior of the material. → FTIR spectra confirmed the formation of SiO 4 and La-O network in the La 10 Si 6 O 27 . → XRD patterns confirmed the formation of pure crystalline La 10 Si 6 O 27 phase. → The grain interior and the grain boundary conductivities are evaluated. - Abstract: Nanocrystalline apatite type structured lanthanum silicate (La 10 Si 6 O 27 ) sample was synthesized by sol-gel process. Thermal behavior of the dried gel of lanthanum silicate sample was studied using TG/DTA. The structural coordination of the dried gel of lanthanum silicate, calcined at various temperatures, was identified from the observed FTIR spectral results. The observed XRD patterns of the calcined dried gel were compared with the ICDD data and confirmed the formation of crystalline lanthanum silicate phase. The average crystalline size of La 10 Si 6 O 27 was calculated using the Scherrer formula and it is found to be ∼80 nm. The observed SEM images of the lanthanum silicate indicate the formation of the spherical particles and the existence of O, Si and La in the lanthanum silicate are confirmed from the SEM-EDX spectrum. The grain and grain boundary conductivities are evaluated by analyzing the measured impedance data, using winfit software, obtained at different temperatures, of La 10 Si 6 O 27 sample. Also, the observed grain and grain boundary conductivity behaviors of the La 10 Si 6 O 27 sample are analysed using brick layer model. The electrical permittivity and electrical modulus were calculated from the measured impedance data and were analyzed by fitting through the Havriliak and Negami function to describe the dielectric relaxation behavior of the nanocrystalline lanthanum silicate.

  2. Effects of electric paravertebral muscle relaxation processes in the athletes heart

    Directory of Open Access Journals (Sweden)

    D. V. Syshko

    2013-02-01

    Full Text Available Influence of paravertebrals miorelaxation on electric processes in a heart at sportsmen is studied. Paravertebrals miorelaxation was the complex of exercises in a water environment directed on the decline of tone of paravertebral muscles. Before and after it was used of paravertebrals miorelaxation registered the indexes of electrocardiography at the sportsmen engaged in the Greek-Roman fight (n=22 by football (n=24 and heavy athletics (n=25. It is got, that at the sportsmen of engaged in the Greek -Roman fight after paravertebrals miorelaxation QRS and QT were it was increased, and R-R and PQ went down. At the sportsmen of engaged in heavy athletics HR and PQ went down after paravertebrals miorelaxation, R-R, QRS and QT were it was increased. At the sportsmen of getting busy by football the PQ interval shortened, and QRS and QT has multiplied. Findings testify to the presence of different mechanisms of adaptation of the conducting system of heart in the conditions of influencing of paravertebrals miorelaxation. These distinctions are fated by two basic factors: by the functional being of the cardio-vessels system on the whole and functional being of sine knot and conducting system of heart in particular.

  3. Electron Transfer between Electrically Conductive Minerals and Quinones

    Directory of Open Access Journals (Sweden)

    Olga Taran

    2017-07-01

    Full Text Available Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconductive minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite, and greigite, and hydroquinones—a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains

  4. Electron Transfer Between Electrically Conductive Minerals and Quinones

    Science.gov (United States)

    Taran, Olga

    2017-07-01

    Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well known, but the impact of abiotic currents across naturally occurring conductive and semiconducitve minerals is poorly understood. In this paper I use cyclic voltammetry to explore electron transfer between electrodes made of common iron minerals (magnetite, hematite, pyrite, pyrrhotite, mackinawite and greigite), and hydroquinones - a class of organic molecules found in carbon-rich sediments. Of all tested minerals, only pyrite and magnetite showed an increase in electric current in the presence of organic molecules, with pyrite showing excellent electrocatalytic performance. Pyrite electrodes performed better than commercially available glassy carbon electrodes and showed higher peak currents, lower overpotential values and a smaller separation between oxidation and reduction peaks for each tested quinone. Hydroquinone oxidation on pyrite surfaces was reversible, diffusion controlled, and stable over a large number of potential cycles. Given the ubiquity of both pyrite and quinones, abiotic electron transfer between minerals and organic molecules is likely widespread in Nature and may contribute to several different phenomena, including anaerobic respiration of a wide variety of microorganisms in temporally anoxic zones or in the proximity of hydrothermal vent chimneys, as well as quinone cycling and the propagation of anoxic zones in organic rich waters. Finally, interactions between pyrite and quinones make use of electrochemical gradients that have been suggested as an important source of energy for the origins of life on Earth. Ubiquinones and iron sulfide clusters are common redox cofactors found in electron transport chains across all domains of life and

  5. Necessity of electrically conductive pili for methanogenesis with magnetite stimulation

    Directory of Open Access Journals (Sweden)

    Oumei Wang

    2018-03-01

    Full Text Available Background Magnetite-mediated direct interspecies electron transfer (DIET between Geobacter and Methanosarcina species is increasingly being invoked to explain magnetite stimulation of methane production in anaerobic soils and sediments. Although magnetite-mediated DIET has been documented in defined co-cultures reducing fumarate or nitrate as the electron acceptor, the effects of magnetite have only been inferred in methanogenic systems. Methods Concentrations of methane and organic acid were analysed with a gas chromatograph and high-performance liquid chromatography, respectively. The concentration of HCl-extractable Fe(II was determined by the ferrozine method. The association of the defined co-cultures of G. metallireducens and M. barkeri with magnetite was observed with transmission electron micrographs. Results Magnetite stimulated ethanol metabolism and methane production in defined co-cultures of G. metallireducens and M. barkeri; however, magnetite did not promote methane production in co-cultures initiated with a culture of G. metallireducens that could not produce electrically conductive pili (e-pili, unlike the conductive carbon materials that facilitate DIET in the absence of e-pili. Transmission electron microscopy revealed that G. metallireducens and M. barkeri were closely associated when magnetite was present, as previously observed in G. metallireducens/G. sulfurreducens co-cultures. These results show that magnetite can promote DIET between Geobacter and Methanosarcina species, but not as a substitute for e-pili, and probably functions to facilitate electron transfer from the e-pili to Methanosarcina. Conclusion In summary, the e-pili are necessary for the stimulation of not only G. metallireducens/G. sulfurreducens, but also methanogenic G. metallireducens/M. barkeri co-cultures with magnetite.

  6. Dielectric relaxation and ac conduction in γ-irradiated UHMWPE/MWCNTs nano composites: Impedance spectroscopy analysis

    International Nuclear Information System (INIS)

    Maqbool, Syed Asad; Mehmood, Malik Sajjad; Mukhtar, Saqlain Saqib; Baluch, Mansoor A.; Khan, Shamim; Yasin, Tariq; Khan, Yaqoob

    2017-01-01

    The dielectric behavior of γ-irradiated ultra-high molecular weight polyethylene (UHMWPE) and its nano composites (NCs) with γ-ray modified multi wall carbon nano tubes (γ-MWCNTs) and MWCNTs had been studied using impedance spectroscopy. The study had been carried out in the frequency range of 20–2 MHz at room temperature. All samples (pure and NCs) were prepared in the form of sheets and irradiated with γ-dose of 50 kGy and 100 kGy, respectively. The comprehensive analysis of results revealed that resistivity of UHMWPE for conduction decreased on irradiation and incorporation of MWCNTs (whether γ ray modified or un-modified) due to the radiation induced damage and conductive networks induced by MWCNTs. At low frequency range a significant increase in the dielectric constant had been observed because of irradiation and addition of MWNCTs. The trend of loss tangent and ac conductivity for each investigated sample depended on resistivity offered and had a decreasing trend as a function of frequency. Moreover, dissipation factor increased with the incorporation of MWNCTs and irradiation from 0.12 to 0.22. In addition to this, non-frequency dependent static dielectric constant was also found to increase with irradiation and incorporation of MWCNTs. The relaxation time was found to increase from 1.2 to 4.3 ms due to hindrance offered by radiation induced mutual cross linking of PE chains and polymer-MWNCTs bindings. - Highlights: • The resistivity for conduction in pristine UHMWPE is decreased with γ-irradiation. • Conduction in PE/MWCNTs nanocomposites increased due to MWCNTs addition. • Static dielectric constant of UHMWPE increased with γ-irradiation. • Static dielectric constant of UHMWPE increased due to MWCNTs incorporation.

  7. Ion doping of surface layers in conducting electrical materials

    International Nuclear Information System (INIS)

    Zukowski, P.; Karwat, Cz.; Kozak, Cz. M.; Kolasik, M.; Kiszczak, K.

    2009-01-01

    The presented article gives basic component elements of an implanter MKPCz-99, its parameters and methods for doping surface layers of conducting electrical materials. The discussed device makes possible to dope the materials with ions of gaseous elements. At the application of cones made of solid-element sheets it is possible to perform doping with atoms that do not chemically react with the modified material. By performing voltage drop measurements with a specialized circuit between a movable testing electrode and the modified sample the dependence of transition resistance on pressure force of the testing electrode on the sample can be determined. The testing can be performed at the current passage of a determined value for surfaces modified with ions of gaseous elements or atoms of solid elements. A computer stand for switch testing makes possible to measure temperature of switch contacts and voltage drop at the contact and thereby to determine contact resistance of a switch depending on the number of switch cycles (ON-OFF). Pattern recording of current and voltage at the switch contacts and the application of an adequate computer software makes possible to determined the value of energy between fixed and moving contacts at their getting apart. In order to eliminate action of the environment onto the switch operation measurements can be performed at placing the tested switch together with the driving system in an atmosphere of noble gas like argon. (authors)

  8. Highly Electrically Conducting Glass-Graphene Nanoplatelets Hybrid Coatings.

    Science.gov (United States)

    Garcia, E; Nistal, A; Khalifa, A; Essa, Y; Martín de la Escalera, F; Osendi, M I; Miranzo, P

    2015-08-19

    Hybrid coatings consisting of a heat resistant Y2O3-Al2O3-SiO2 (YAS) glass containing 2.3 wt % of graphene nanoplatelets (GNPs) were developed by flame spraying homogeneous ceramic powders-GNP granules. Around 40% of the GNPs survived the high spraying temperatures and were distributed along the splat-interfaces, forming a percolated network. These YAS-GNP coatings are potentially interesting in thermal protection systems and electromagnetic interference shields for aerospace applications; therefore silicon carbide (SiC) materials at the forefront of those applications were employed as substrates. Whereas the YAS coatings are nonconductive, the YAS-GNP coatings showed in-plane electrical conductivity (∼10(2) S·m(-1)) for which a low percolation limit (below 3.6 vol %) is inferred. Indentation tests revealed the formation of a highly damaged indentation zone showing multiple shear displacements between adjacent splats probably favored by the graphene sheets location. The indentation radial cracks typically found in brittle glass coatings are not detected in the hybrid coatings that are also more compliant.

  9. Gum ghatti based novel electrically conductive biomaterials: A study of conductivity and surface morphology

    Directory of Open Access Journals (Sweden)

    S. Kalia

    2014-04-01

    Full Text Available Gum ghatti-cl-poly(acrylamide-aniline interpenetrating network (IPN was synthesized by a two-step aqueous polymerization method, in which aniline monomer was absorbed into the network of gum ghatti-cl-poly(acrylamide and followed by a polymerization reaction between aniline monomers. Initially, semi-IPN based on acrylamide and gum ghatti was prepared by free-radical copolymerization in aqueous media with optimized process parameters, using N,N'-methylenebis-acrylamide, as cross-linker and ammonium persulfate, as an initiator system. Optimum reaction conditions affording maximum percentage swelling were: solvent [mL] =12, Acrylamide (AAm [mol•L–1] = 1.971, Ammonium peroxydisulfate (APS [mol•L–1] = 0.131•10–1, N,N'-methylene-bis-acrylamide (MBA [mol•L–1] = 0.162•10–1, reaction time [min] = 210, temperature [°C] = 100 and pH = 7.0. The resulting IPN was doped with different protonic acids. The effect of the doping has been investigated on the conductivity and surface morphology of the IPN hydrogel. The maximum conductivity was observed with 1.5N HClO4 concentration. The morphological, structural and electrical properties of the candidate polymers were studied using scanning electron micrscopy (SEM, Fourier transform infrared spectroscopy FTIR and two-probe method, respectively.

  10. Reversible conduction block in peripheral nerve using electrical waveforms.

    Science.gov (United States)

    Bhadra, Niloy; Vrabec, Tina L; Bhadra, Narendra; Kilgore, Kevin L

    2018-01-01

    Electrical nerve block uses electrical waveforms to block action potential propagation. Two key features that distinguish electrical nerve block from other nonelectrical means of nerve block: block occurs instantly, typically within 1 s; and block is fully and rapidly reversible (within seconds). Approaches for achieving electrical nerve block are reviewed, including kilohertz frequency alternating current and charge-balanced polarizing current. We conclude with a discussion of the future directions of electrical nerve block. Electrical nerve block is an emerging technique that has many significant advantages over other methods of nerve block. This field is still in its infancy, but a significant expansion in the clinical application of this technique is expected in the coming years.

  11. Dielectric relaxation and AC conductivity studies of Se90Cd10−xInx glassy alloys

    Directory of Open Access Journals (Sweden)

    Nitesh Shukla

    2016-06-01

    Full Text Available Chalcogenide glassy alloys of Se90Cd10−xInx (x = 2, 4, 6, 8 are synthesized by melt quench technique. The prepared glassy alloys have been characterized by techniques such as differential scanning calorimetry (DSC, scanning electron microscopy (SEM and energy dispersive X-ray (EDAX. Dielectric properties of Se90Cd10−xInx (x = 2, 4, 6, 8 chalcogenide glassy system have been studied using impedance spectroscopic technique in the frequency range 42 Hz to 5 MHz at room temperature. It is found that the dielectric constants ɛ′, dielectric loss factor ɛ″ and loss angle Tan δ depend on frequency. ɛ′, ɛ″ and loss angle Tan δ are found to be decreasing with the In content in Se90Cd10−xInx glassy system. AC conductivity of the prepared sample has also been studied. It is found that AC conductivity increases with frequency where as it has decreasing trend with increasing In content in Se–Cd matrix. The semicircles observed in the Cole–Cole plots indicate a single relaxation process.

  12. Reversible Control of Anisotropic Electrical Conductivity using Colloidal Microfluidic Networks

    National Research Council Canada - National Science Library

    Beskok, Ali; Bevan, Michael; Lagoudas, Dimitris; Ounaies, Zoubeida; Bahukudumbi, Pradipkumar; Everett, William

    2007-01-01

    This research addresses the tunable assembly of reversible colloidal structures within microfluidic networks to engineer multifunctional materials that exhibit a wide range of electrical properties...

  13. An electrical method for the measurement of the thermal and electrical conductivity of reduced graphene oxide nanostructures.

    Science.gov (United States)

    Schwamb, Timo; Burg, Brian R; Schirmer, Niklas C; Poulikakos, Dimos

    2009-10-07

    This paper introduces an electrical four-point measurement method enabling thermal and electrical conductivity measurements of nanoscale materials. The method was applied to determine the thermal and electrical conductivity of reduced graphene oxide flakes. The dielectrophoretically deposited samples exhibited thermal conductivities in the range of 0.14-2.87 W m(-1) K(-1) and electrical conductivities in the range of 6.2 x 10(2)-6.2 x 10(3) Omega(-1) m(-1). The measured properties of each flake were found to be dependent on the duration of the thermal reduction and are in this sense controllable.

  14. High thermal conductivity connector having high electrical isolation

    Science.gov (United States)

    Nieman, Ralph C.; Gonczy, John D.; Nicol, Thomas H.

    1995-01-01

    A method and article for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection. The connection method involves clamping, by thermal interference fit, an electrically isolating cylinder between an outer metallic ring and an inner metallic disk. The connection provides durable coupling of a heat sink and a heat source.

  15. Noninvasive electrical conductivity measurement by MRI. A test of its validity and the electrical conductivity characteristics of glioma

    Energy Technology Data Exchange (ETDEWEB)

    Tha, Khin Khin; Kudo, Kohsuke [Hokkaido University Hospital, Department of Diagnostic and Interventional Radiology, N-14, W-5, Kita-ku, Sapporo (Japan); Hokkaido University, Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education, Sapporo (Japan); Katscher, Ulrich; Stehning, Christian [Philips Research Laboratories, Hamburg (Germany); Yamaguchi, Shigeru; Terasaka, Shunsuke; Kazumata, Ken [Faculty of Medicine, Hokkaido University, Department of Neurosurgery, Sapporo (Japan); Fujima, Noriyuki [Hokkaido University Hospital, Department of Diagnostic and Interventional Radiology, N-14, W-5, Kita-ku, Sapporo (Japan); Yamamoto, Toru [Hokkaido University, Faculty of Health Sciences, Sapporo (Japan); Van Cauteren, Marc [Clinical Science Philips Healthtech Asia Pacific, Tokyo (Japan); Shirato, Hiroki [Hokkaido University, Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education, Sapporo (Japan); Faculty of Medicine, Hokkaido University, Department of Radiation Medicine, Sapporo (Japan)

    2018-01-15

    This study noninvasively examined the electrical conductivity (σ) characteristics of diffuse gliomas using MRI and tested its validity. MRI including a 3D steady-state free precession (3D SSFP) sequence was performed on 30 glioma patients. The σ maps were reconstructed from the phase images of the 3D SSFP sequence. The σ histogram metrics were extracted and compared among the contrast-enhanced (CET) and noncontrast-enhanced tumour components (NCET) and normal brain parenchyma (NP). Difference in tumour σ histogram metrics among tumour grades and correlation of σ metrics with tumour grades were tested. Validity of σ measurement using this technique was tested by correlating the mean tumour σ values measured using MRI with those measured ex vivo using a dielectric probe. Several σ histogram metrics of CET and NCET of diffuse gliomas were significantly higher than NP (Bonferroni-corrected p ≤.045). The maximum σ of NCET showed a moderate positive correlation with tumour grade (r =.571, Bonferroni-corrected p =.018). The mean tumour σ measured using MRI showed a moderate positive correlation with the σ measured ex vivo (r =.518, p =.040). Tissue σ can be evaluated using MRI, incorporation of which may better characterise diffuse gliomas. (orig.)

  16. Transcardiac conducted electrical weapon (TASER) probe deployments: incidence and outcomes.

    Science.gov (United States)

    Bozeman, William P; Teacher, Eric; Winslow, James E

    2012-12-01

    TASER (TASER International, Scottsdale, AZ) conducted electrical weapons (CEWs) are commonly used by law enforcement officers. Although animal studies have suggested that transcardiac CEW discharges may produce direct cardiac effects, this has not been demonstrated in human studies. This study sought to determine the incidence and outcomes of transcardiac CEW probe impact locations in a large series of actual CEW deployments. A multi-center database of consecutive CEW uses by law enforcement officers was retrospectively reviewed. Case report forms were independently reviewed by three investigators to identify cases with paired probe configurations potentially producing a transcardiac discharge vector. Descriptive analysis was performed and inter-rater reliability was assessed. Among 1201 total CEW uses, 813 included probe deployments and 178 cases had paired anterior probe impacts potentially capable of producing a transcardiac discharge vector. This represents 14.8% of all CEW uses (95% confidence interval [CI] 12.9-16.9%) and 21.9% of CEW uses in probe mode (95% CI 19.1-24.9%). Inter-rater agreement was very good, with kappa = 0.82. There were no immediate deaths in any cases (97.5% CI 0.0-0.3%) to suggest a cardiac dysrhythmia, including those with transcardiac discharge vector. CEW deployments with probe impact configurations capable of producing a transcardiac discharge occur in a minority of cases in field use conditions. None of these cases, transcardiac or otherwise, produced immediately fatal dysrhythmias. These data support the overall safety of CEWs and provide a benchmark estimate of the likelihood of transcardiac discharge vectors occurring in field use of CEWs. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Conducted electrical weapon (TASER) use against minors: a shocking analysis.

    Science.gov (United States)

    Gardner, Alison R; Hauda, William E; Bozeman, William P

    2012-09-01

    Conducted electrical weapons (CEWs) such as the TASER are often used by law enforcement (LE) personnel during suspect apprehension. Previous studies have reported an excellent safety profile and few adverse outcomes with CEW use in adults. We analyzed the safety and injury profile of CEWs when used during LE apprehension of children and adolescents, a potentially vulnerable population. Consecutive CEW uses by LE officers against criminal suspects were tracked at 10 LE agencies and entered into a database as part of an ongoing multicenter injury surveillance program. All CEW uses against minors younger than 18 years were retrieved for analysis. Primary outcomes included the incidence and type of mild, moderate, and severe CEW-related injury, as assessed by physician reviewers in each case. Ultimate outcomes, suspect demographics, and circumstances surrounding LE involvement are reported secondarily. Of 2026 consecutive CEW uses, 100 (4.9%) were uses against minor suspects. Suspects ranged from 13 to 17 years, with a mean age of 16.1 (SD, 0.99) years (median, 16 years). There were no significant (moderate or severe) injuries reported (0%; 97.5% confidence interval, 0.0%-3.6%). Twenty suspects (20%; 95% confidence interval, 12.7%-29.1%) were noted to sustain 34 mild injuries. The majority of these injuries (67.6%) were expected superficial punctures from CEW probes. Other mild injuries included superficial abrasions and contusions in 7 cases (7%). None of the minor suspects studied sustained significant injury, and only 20% reported minor injuries, mostly from the expected probe puncture sites. These data suggest that adolescents are not at a substantially higher risk than adults for serious injuries after CEW use.

  18. Microstructural inhomogeneity of electrical conductivity in subcutaneous fat tissue.

    Directory of Open Access Journals (Sweden)

    Ilja L Kruglikov

    Full Text Available Microscopic peculiarities stemming from a temperature increase in subcutaneous adipose tissue (sWAT after applying a radio-frequency (RF current, must be strongly dependent on the type of sWAT. This effect is connected with different electrical conductivities of pathways inside (triglycerides in adipocytes and outside (extra-cellular matrix the cells and to the different weighting of these pathways in hypertrophic and hyperplastic types of sWAT. The application of the RF current to hypertrophic sWAT, which normally has a strongly developed extracellular matrix with high concentrations of hyaluronan and collagen in a peri-cellular space of adipocytes, can produce, micro-structurally, a highly inhomogeneous temperature distribution, characterized by strong temperature gradients between the peri-cellular sheath of the extra-cellular matrix around the hypertrophic adipocytes and their volumes. In addition to normal temperature effects, which are generally considered in body contouring, these temperature gradients can produce thermo-mechanical stresses on the cells' surfaces. Whereas these stresses are relatively small under normal conditions and cannot cause any direct fracturing or damage of the cell structure, these stresses can, under some supportive conditions, be theoretically increased by several orders of magnitude, causing the thermo-mechanical cell damage. This effect cannot be realized in sWAT of normal or hyperplastic types where the peri-cellular structures are under-developed. It is concluded that the results of RF application in body contouring procedures must be strongly dependent on the morphological structure of sWAT.

  19. The Wilkes subglacial basin eastern margin electrical conductivity anomaly

    Science.gov (United States)

    Rizzello, Daniele; Armadillo, Egidio; Ferraccioli, Fausto; Caneva, Giorgio

    2014-05-01

    allowed for a new processing of a wide dataset acquired during three different international Antarctic campaigns supported by the Italian Antarctic Project: the BACKTAM, WIBEM and WISE expeditions. The qualitative analysis of the induction arrows, in the period range 20-170 s, reveals an approximately 2D regional electrical conductivity pattern with a clear differentiation between the three Terrains crossed by the GDS transect we have re-analized: the Robertson Bay, the Bowers and the Wilson Terrain. Bi-dimensional conductivity models, jointly with magnetic and gravimetric profiles, suggest a differentiation of the investigated area in three crustal sectors separated by the Daniels Range and the Bowers Mts., in close relation with main known structural lineaments; to the West, a deep conductivity anomaly is associated with the transition to the Wilkes Subglagial Basin. We deem that such anomaly, together with the magnetic and gravimetric signatures, is compatible with an extensional regime in the eastern margin of the WSB. References Rizzello, D., Armadillo, E., Manzella, A."Statistical analysis of the polar electrojet influence on geomagnetic transfer functions estimates, over wide time and space scales". EGU 2013 General Assembly, Wien - poster presentation.

  20. AC/DC electrical conduction and dielectric properties of PMMA/PVAc/C60 down-shifting nanocomposite films

    Science.gov (United States)

    El-Bashir, S. M.; Alwadai, N. M.; AlZayed, N.

    2018-02-01

    Polymer nanocomposite films were prepared by doping fullerene C60 in polymer blend composed of polymethacrylate/polyvinyl acetate blends (PMMA/PVAc) using solution cast technique. The films were characterized by differential scanning calorimeter (DSC), Transmission electron microscope (TEM), DC/AC electrical conductivity and dielectric measurements in the frequency range (100 Hz- 1 MHz). The glass transition temperature, Tg, was increased by increasing the concentration of fullerene C60; this property reflects the increase of thermal stability by increasing the nanofiller content. The DC and AC electrical conductivities were enhanced by increasing C60 concentration due to the electron hopping or tunneling between filled and empty localized states above Tg. The relaxation time was determined from the αβ -relaxations and found to be attenuated by increasing the temperature as a typical behavior of amorphous polymers. The calculated values of thermodynamic parameters revealed the increase of molecular stability by increasing the doping concentration; this feature supports the application of PMMA/PVAc/C60 nanocomposite films in a wide scale of solar energy conversion applications such as luminescent down-shifting (LDS) coatings for photovoltaic cells.

  1. Electrical conductivity of metal–carbon nanotube structures: Effect of ...

    Indian Academy of Sciences (India)

    Administrator

    The electrical properties of asymmetric metal–carbon nanotube (CNT) structures have been studied using ... The models with asymmetric metal contacts and carbon nanotube bear resemblance to experimental ... ordinary mechanical strength.

  2. Electrical Conductivity of CUXS Thin Film Deposited by Chemical ...

    African Journals Online (AJOL)

    acer

    Nigerian Journal of Basic and Applied Science (2009), 17(2): 161-165. ISSN 0794-5698. Electrical ... Department of Physics, University of Abuja, P. M. B. 117, Abuja, Nigeria. [*Correspondence ... ease of handling and ease of application to.

  3. Materials and methods for autonomous restoration of electrical conductivity

    Science.gov (United States)

    Blaiszik, Benjamin J; Odom, Susan A; Caruso, Mary M; Jackson, Aaron C; Baginska, Marta B; Ritchey, Joshua A; Finke, Aaron D; White, Scott R; Moore, Jeffrey S; Sottos, Nancy R; Braun, Paul V; Amine, Khalil

    2014-03-25

    An autonomic conductivity restoration system includes a solid conductor and a plurality of particles. The particles include a conductive fluid, a plurality of conductive microparticles, and/or a conductive material forming agent. The solid conductor has a first end, a second end, and a first conductivity between the first and second ends. When a crack forms between the first and second ends of the conductor, the contents of at least a portion of the particles are released into the crack. The cracked conductor and the released contents of the particles form a restored conductor having a second conductivity, which may be at least 90% of the first conductivity.

  4. Electrical Conduction of Ba(Ti0.99Fe0.01)O3-δ Ceramic at High Temperatures

    Science.gov (United States)

    Yu, Zi-De; Chen, Xiao-Ming

    2018-03-01

    BaTiO3 and Ba(Ti0.99Fe0.01)O3-δ ceramics with dense microstructure have been synthesized by a solid-state reaction method, and their electrical conduction investigated by broadband electrical impedance spectroscopy at frequencies from 0.05 Hz to 3 × 106 Hz and temperatures from 200°C to 400°C. Compared with BaTiO3, the real part of the permittivity and the phase-transition temperature of Ba(Ti0.99Fe0.01)O3-δ decreased. Relaxation peaks appeared in the curves of the imaginary part of the permittivity as a function of frequency. With increase in frequency, the peaks gradually shifted towards higher frequency and their height increased. Conductivity was closely related to frequency and temperature. Frequency-dependent conductivity was analyzed using the Jonscher double power law. Compared with BaTO3, Ba(Ti0.99Fe0.01)O3-δ exhibited high impedance at given frequency and temperature. Impedance Cole-Cole plots displayed two semicircles, which could be well fit using two parallel RC equivalent circuit models. The conductivity activation energy was found to be around 1 eV. For Ba(Ti0.99Fe0.01)O3-δ , the electrical modulus curve versus frequency displayed two peaks.

  5. Maximum on the electrical conductivity polytherm of molten TeCl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, Alexander B.; Potapov, Alexei M. [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry

    2017-09-01

    The electrical conductivity of molten TeCl{sub 4} was measured up to 761 K, i.e. 106 degrees above the normal boiling point of the salt. For the first time it was found that TeCl{sub 4} electrical conductivity polytherm has a maximum. It was recorded at 705 K (Κ{sub max}=0.245 Sm/cm), whereupon the conductivity decreases as the temperature rises. The activation energy of electrical conductivity was calculated.

  6. Maximum on the electrical conductivity polytherm of molten TeCl4

    International Nuclear Information System (INIS)

    Salyulev, Alexander B.; Potapov, Alexei M.

    2017-01-01

    The electrical conductivity of molten TeCl 4 was measured up to 761 K, i.e. 106 degrees above the normal boiling point of the salt. For the first time it was found that TeCl 4 electrical conductivity polytherm has a maximum. It was recorded at 705 K (Κ max =0.245 Sm/cm), whereupon the conductivity decreases as the temperature rises. The activation energy of electrical conductivity was calculated.

  7. Kaempferol enhances endothelium-dependent relaxation in the porcine coronary artery through activation of large-conductance a2+-activated K+ channels

    Science.gov (United States)

    Xu, Y C; Leung, S W S; Leung, G P H; Man, R Y K

    2015-01-01

    Background and Purpose Kaempferol, a plant flavonoid present in normal human diet, can modulate vasomotor tone. The present study aimed to elucidate the signalling pathway through which this flavonoid enhanced relaxation of vascular smooth muscle. Experimental Approach The effect of kaempferol on the relaxation of porcine coronary arteries to endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) relaxing agents was studied in an in vitro organ chamber setup. The whole-cell patch-clamp technique was used to determine the effect of kaempferol on potassium channels in porcine coronary artery smooth muscle cells (PCASMCs). Key Results At a concentration without direct effect on vascular tone, kaempferol (3 × 10−6 M) enhanced relaxations produced by bradykinin and sodium nitroprusside. The potentiation by kaempferol of the bradykinin-induced relaxation was not affected by Nω-nitro-L-arginine methyl ester, an inhibitor of NO synthase (10−4 M) or TRAM-34 plus UCL 1684, inhibitors of intermediate- and small-conductance calcium-activated potassium channels, respectively (10−6 M each), but was abolished by tetraethylammonium chloride, a non-selective inhibitor of calcium-activated potassium channels (10−3 M), and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channel (KCa1.1; 10−7 M). Iberiotoxin also inhibited the potentiation by kaempferol of sodium nitroprusside-induced relaxations. Kaempferol stimulated an outward-rectifying current in PCASMCs, which was abolished by iberiotoxin. Conclusions and Implications The present results suggest that, in smooth muscle cells of the porcine coronary artery, kaempferol enhanced relaxations caused by endothelium-derived and exogenous NO as well as those due to endothelium-dependent hyperpolarization. This vascular effect of kaempferol involved the activation of KCa1.1 channels. PMID:25652142

  8. Kaempferol enhances endothelium-dependent relaxation in the porcine coronary artery through activation of large-conductance Ca(2+) -activated K(+) channels.

    Science.gov (United States)

    Xu, Y C; Leung, S W S; Leung, G P H; Man, R Y K

    2015-06-01

    Kaempferol, a plant flavonoid present in normal human diet, can modulate vasomotor tone. The present study aimed to elucidate the signalling pathway through which this flavonoid enhanced relaxation of vascular smooth muscle. The effect of kaempferol on the relaxation of porcine coronary arteries to endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) relaxing agents was studied in an in vitro organ chamber setup. The whole-cell patch-clamp technique was used to determine the effect of kaempferol on potassium channels in porcine coronary artery smooth muscle cells (PCASMCs). At a concentration without direct effect on vascular tone, kaempferol (3 × 10(-6) M) enhanced relaxations produced by bradykinin and sodium nitroprusside. The potentiation by kaempferol of the bradykinin-induced relaxation was not affected by N(ω)-nitro-L-arginine methyl ester, an inhibitor of NO synthase (10(-4) M) or TRAM-34 plus UCL 1684, inhibitors of intermediate- and small-conductance calcium-activated potassium channels, respectively (10(-6) M each), but was abolished by tetraethylammonium chloride, a non-selective inhibitor of calcium-activated potassium channels (10(-3) M), and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channel (KCa 1.1; 10(-7) M). Iberiotoxin also inhibited the potentiation by kaempferol of sodium nitroprusside-induced relaxations. Kaempferol stimulated an outward-rectifying current in PCASMCs, which was abolished by iberiotoxin. The present results suggest that, in smooth muscle cells of the porcine coronary artery, kaempferol enhanced relaxations caused by endothelium-derived and exogenous NO as well as those due to endothelium-dependent hyperpolarization. This vascular effect of kaempferol involved the activation of KCa 1.1 channels. © 2015 The British Pharmacological Society.

  9. Electric field studies: TLE-induced waveforms and ground conductivity impact on electric field propagation

    Science.gov (United States)

    Farges, Thomas; Garcia, Geraldine; Blanc, Elisabeth

    2010-05-01

    propagation of the electromagnetic waves generated by lightning has also been studied in the frequency range 1 kHz-1MHz at distances lower than 1000 km from the lightning source. A propagation model has been developed to determine the ground waves which propagate in a homogenous medium using the analytical expression given by Maclean and Wu [1993]. This approach takes into account the electric finite conductivity and the fact that the Earth is spherical, which allow us to deal with over-the-horizon propagation. We installed in 2008 four stations which were more or less aligned - the maximum distance between two stations was about 870 km. Two stations were located close to the Mediterranean Sea and the two others inside the continent, at the centre of France. This station distribution and the observation period (from August to December) allowed statistical and physical studies, such as the influence of the electric conductivity on wave propagation. Comparison of electric field spectra, measured after propagation only over sea and only over ground, showed clearly the effects of ground conductivity on propagation. Comparison between observations and modelling has been used to evaluate the ground conductivity. In the future we will implement the sky-wave inside our model and validate it with the database.

  10. Investigations on electrical conductivity and dielectric properties of Na doped ZnO synthesized from sol gel method

    Energy Technology Data Exchange (ETDEWEB)

    Tabib, Asma; Sdiri, Nasr [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Elhouichet, Habib, E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, University Tunis El Manar, Tunis 2092 (Tunisia); Férid, Mokhtar [Laboratoire de Physico-Chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, B.P. 95 Hammam-Lif, 2050 (Tunisia)

    2015-02-15

    Highlights: • ZnO nanoparticles doped with Na were prepared from sol-gel method. • Electric conductivity and dielectric properties were investigated. • The ZnO conductivity is estimated to be of p-type for critical Na doping of 1.5% at. - Abstract: Na doped ZnO nanoparticles (NPs) were elaborated by sol gel technique. The X-ray diffraction patterns show that the peaks are indexed to the hexagonal structure without any trace of an extra phase. Electric and dielectric properties were investigated using complex impedance spectroscopy. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE). The contribution of grain boundary resistance to the total resistance of the system is remarkable. The AC conductivity increases with temperature following the Arrhenius law, with single apparent activation energy for conduction process. The frequency dependence of the electric conductivity follows a simple power law behavior, in according to relation σ{sub AC}(ω) = σ(0) + A ω{sup s}, where s is smaller than 1. The analysis of dc conductivity indicates that the conduction is ionic in nature. The study of its variation, at fixed temperature, with Na content shows sharp decrease which is explained by the formation of Na{sub Zn} acceptor. It was found that the dc conductivity reaches its minimum value for critical Na concentration of 1.5% at which the conductivity is estimated to be of p-type. Impedance and modulus study reveals the temperature dependent non-Debye type relaxation phenomenon. Dielectric studies revealed a promising dielectric properties (relatively high ε′ at low frequencies and low loss at high frequencies). In the low-frequency region, the values of M′ tends to zero suggesting negligible or absent electrode polarization phenomenon. The frequency dependent maxima in the imaginary modulus are found to obey to Arrhenius law.

  11. Application of Electromagnetic Induction to Monitor Changes in Soil Electrical Conductivity Profiles in Arid Agriculture

    KAUST Repository

    Jadoon, K.Z.

    2015-09-06

    In this research, multi-configuration electromagnetic induction (EMI) measurements were conducted in a corn field to estimate variation in soil electrical conductivity profiles in the roots zone. Electromagnetic forward model based on the full solution of Maxwell\\'s equation was used to simulate the apparent electrical conductivity measured with EMI system (the CMD mini-Explorer). Joint inversion of multi-configuration EMI measurements were performed to estimate the vertical soil electrical conductivity profiles. The inversion minimizes the misfit between the measured and modeled soil apparent electrical conductivity by DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm, which is based on Bayesain approach. Results indicate that soil electrical conductivity profiles have low values close to the corn plants, which indicates loss of soil moisture due to the root water uptake. These results offer valuable insights into future potential and emerging challenges in the development of joint analysis of multi-configuration EMI measurements to retrieve effective soil electrical conductivity profiles.

  12. Electrical Properties and Dipole Relaxation Behavior of Zinc-Substituted Cobalt Ferrite

    Science.gov (United States)

    Supriya, Sweety; Kumar, Sunil; Kar, Manoranjan

    2017-12-01

    Co1- x Zn x Fe2O4 ceramics with x = 0.00, 0.05, 0.10, 0.15 and 0.20 were synthesized by a modified citric acid sol-gel method. The crystalline phase of the samples was characterized by the powder x-ray diffraction technique (XRD) and the Rietveld analysis of the XRD patterns. The morphology and particle size were studied using field emission scanning electron microscopy. Fourier transform infrared spectroscopy studies were consistent with the XRD results. The impedance measurements were carried out from 100 Hz to 10 MHz at different temperatures from 40°C to 300°C. The frequency dispersion of dielectric was analyzed with a modified Debye equation. The activation energy derived from the dielectric constant and the impedance follows the Arrhenius law and are comparable with each other. The dielectric relaxation and impedance relaxation are correlated in terms of activation energy, show a good temperature stability of the dielectrics and are useful for their applications in microelectronic devices such as filters, capacitors, resonators, etc.

  13. Improvement of Thermal and Electrical Conductivity of Epoxy/boron Nitride/silver Nanoparticle Composite

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seungyong; Lim, Soonho [Korea Institute of Science and Technology, Wanju (Korea, Republic of)

    2017-06-15

    In this study, we investigated the effect of BN (boron nitride) on the thermal and the electrical conductivity of composites. In case of epoxy/BN composites, the thermal conductivity was increased as the BN contents were increased. Epoxy/AgNP (Ag nanoparticle) nanocomposites exhibited a slight change of thermal conductivity and showed a electrical percolation threshold at 20 vol% of Ag nanoparticles. At the fixed Ag nanoparticle content below the electrical percolation threshold, increasing the amount of BN enhanced the electrical conductivity as well as thermal conductivity for the epoxy/AgNP/BN composites.

  14. Solvothermal synthesis and electrical conductivity model for the zinc oxide-insulated oil nanofluid

    International Nuclear Information System (INIS)

    Shen, L.P.; Wang, H.; Dong, M.; Ma, Z.C.; Wang, H.B.

    2012-01-01

    A new kind of nanofluid, ZnO-insulated oil nanofluid was prepared from ZnO nanoparticles synthesized by solvothermal method. Electrical property measurement shows that the electrical conductivity increases by 973 times after adding 0.75% volumetric fraction of ZnO nanoparticles into the insulated oil. A linear dependence of the electrical conductivity on the volumetric fraction has been observed, while the temperature dependence of the electrical conductivity reveals a nonlinear relationship. An electrical conductivity model is established for the nanofluid by considering both the Brownian motion and electrophoresis of the ZnO nanoparticles. -- Highlights: ► Stable ZnO-insulated oil nanofluid was successfully prepared. ► The electrical conductivity of the ZnO nanofluid is investigated. ► A new model is established to explain the electrical properties of the nanofluid.

  15. Electrical conductivity of highly ionized dense hydrogen plasma

    International Nuclear Information System (INIS)

    Radtke, R.; Guenther, K.

    1976-01-01

    A diagnostic technique for the determination of pressure, temperature and its radial distribution, the strength of the electric field and the current of a wall-stabilized pulse hydrogen arc at a pressure of 10 atm and a maximum power of 120 kW/cm arc length is developed. (author)

  16. Electrical conductivity of metal–carbon nanotube structures

    Indian Academy of Sciences (India)

    The electrical properties of asymmetric metal–carbon nanotube (CNT) structures have been studied using density functional theory and non-equilibrium Green's function method with Atomistix tool kit. The models with asymmetric metal contacts and carbon nanotube bear resemblance to experimental set-ups. The study ...

  17. Electrical conductivity of polytetrafluoroethylene in dc and ac electric fields under continuous electron bombardment

    International Nuclear Information System (INIS)

    Khatipov, S.A.; Turdybekov, K.M.; Milinchuk, V.K.

    1993-01-01

    A study has been made of the time of the radiation current density in dc and ac (10 2 -5-10 3 Hz) electric fields (10 3 -5-10 5 V/cm) at temperatures from 80 to 393 K and dose rates from 5-10 3 Gy/sec, for PTFE films (50-180 μm) with various thermal prehistories, when exposed to continuous bombardment by 9-MeV electrons. It has been shown that the experimental results cannot be interpreted from the standpoint of free-charge conduction; they can be explained qualitatively within the framework of concepts of inhomogeneous ionization of the substance, due to the formation of short tracks

  18. Electric conductivity of molten mixtures of ternary mutual KF-KCl-ZrF4 system

    International Nuclear Information System (INIS)

    Darienko, S.E.; Raspopin, S.P.; Chervinskij, Yu.F.

    1988-01-01

    Using the relative capillary method at the frequency of 50 kHz the specific electric conductivity of molten mixtures of the KF-KCl-ZnF 4 system is measured. All the measurements were made in the atmosphere of purified argon. Temperature dependence of electric conductivity of the mixtures studied (800-1260 K) is described by the equations of exponential type with sufficient accuracy. Curves of identical specific electric conductivity of the three-component system are presented. With an increase in zirconium tetrachloride concentration in the mixtures electric conductivity of the melts decreases. On the basis of the measurement results of KF-ZrF 4 and KCl-ZrF 4 molten mixture specific electric conductivity and data on the melt density the values of molar electric conductivity at 1200 K are calculated

  19. AC electrical conductivity in amorphous indium selenide thin films

    International Nuclear Information System (INIS)

    Di Giulio, H.; Rella, R.; Tepore, A.

    1987-01-01

    In order to obtain additional information about the nature of the conduction mechanism in amorphous InSe films results of an experimental study concerning the frequency and temperature dependence of the ac conductivity are reported. The measurements were performed on specimens of different thickness and different electrode contact areas. The results can be explained assuming that conduction occurs by phonon-assisted hopping between localized states near the Fermi level

  20. Electrical conductivity measurements of aqueous and immobilized potassium hydroxide

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mollerup, Pia Lolk

    2012-01-01

    concentrations was investigated using the van der Pauw method in combination with electrochemical impedance spectroscopy (EIS). Conductivity values as high as 2.7 S cm−1 for 35 wt%, 2.9 S cm−1 for 45 wt%, and 2.8 S cm−1 for 55 wt% concentrated aqueous solutions were measured at 200 °C. Micro- and nano-porous...... solid pellets were produced and used to immobilize aqueous KOH solutions. These are intended to operate as ion-conductive diaphragms (electrolytes) in alkaline electrolysis cells, offering high conductivity and corrosion resistance. The conductivity of immobilized KOH has been determined by the same...

  1. Conductive polymer composites with carbonic fillers: Shear induced electrical behaviour

    Czech Academy of Sciences Publication Activity Database

    Starý, Zdeněk; Krückel, J.

    2018-01-01

    Roč. 139, 14 March (2018), s. 52-59 ISSN 0032-3861 R&D Projects: GA ČR(CZ) GA17-05654S; GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : polymer-matrix composites * carbon fibres * electrical properties Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer sci ence Impact factor: 3.684, year: 2016

  2. Enhancement of electrical conductivity in gamma irradiated cobalt ferrite nanoparticles

    International Nuclear Information System (INIS)

    Nawpute, Asha A.; Raut, A.V.; Babrekar, M.K.; Kale, C.M.; Jadhav, K.M.; Shinde, A.B.

    2014-01-01

    The cobalt ferrite nanoparticles were synthesized by sol-gel auto- combustion method, in which L-ascorbic acid was used as a fuel. The effect of gamma irradiation on the electrical resistivity of cobalt ferrite nanoparticles has been studied. The ferrite powder annealed at 550℃ was irradiated by gamma source 137 Cs. The synthesized nanoparticles were characterized by X-ray diffraction and DC resistivity. (author)

  3. Electrical conduction in composites containing copper core–copper ...

    Indian Academy of Sciences (India)

    Unknown

    of Mott's small polaron hopping conduction model. ... sample exhibited a metallic conduction confirming the formation of a percolative chain of ..... value of εp. Also the oxide layer formation on the initially unoxidized copper particles will increase the resistivity level of the nanocomposite. This is borne out by results shown in ...

  4. Thermal switching of the electrical conductivity of Si(111)([Formula

    DEFF Research Database (Denmark)

    Wells, J W; Kallehauge, Jesper; Hofmann, Ph

    2007-01-01

    The temperature-dependent surface conductivity of the Si(111)([Formula: see text])Ag surface was measured using a microscopic four-point probe. The conductivity was found to undergo a sharp increase of about three orders of magnitude when the system was heated above about 220 K. This strong...... conductivity change is reversible and attributed to the phase transition which is generally believed to occur on this surface. It is also shown that, in order to find the true surface conductivity, it is necessary to separate it from the contribution of the bulk and space charge layer. In this work......, this is achieved by using a finite-element model. A percolating network of Ag islands on Si(111) was also studied and a much simpler behaviour (compared to that of Si(111)([Formula: see text])Ag) was found. The temperature-dependent conductivity of this system was found to display typical metallic behaviour...

  5. Bentonite electrical conductivity: a model based on series–parallel transport

    KAUST Repository

    Lima, Ana T.

    2010-01-30

    Bentonite has significant applications nowadays, among them as landfill liners, in concrete industry as a repairing material, and as drilling mud in oil well construction. The application of an electric field to such perimeters is under wide discussion, and subject of many studies. However, to understand the behaviour of such an expansive and plastic material under the influence of an electric field, the perception of its electrical properties is essential. This work serves to compare existing data of such electrical behaviour with new laboratorial results. Electrical conductivity is a pertinent parameter since it indicates how much a material is prone to conduct electricity. In the current study, total conductivity of a compacted porous medium was established to be dependent upon density of the bentonite plug. Therefore, surface conductivity was addressed and a series-parallel transport model used to quantify/predict the total conductivity of the system. © The Author(s) 2010.

  6. An electrical conductivity inspection methodology of polycrystalline diamond cutters

    Science.gov (United States)

    Bogdanov, G.; Wiggins, J.; Bertagnolli, K.; Ludwig, R.

    2012-05-01

    The polycrystalline diamond cutter (PDC) is widely used in oil and gas drilling operations. It is manufactured by sintering diamond powder onto a tungsten carbide substrate at 6 GPa and 1500 C. During sintering, molten cobalt from the substrate infiltrates the diamond table. The residual metal content correlates with cutter performance. We present an instrument that employs electrical impedance tomography capable of imaging the 3D metal content distribution in the diamond table. These images can be used to predict cutter performance as well as detect flaws.

  7. Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

    Science.gov (United States)

    Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

    2013-11-01

    High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN2). Electrical conductivity of PPLP in LN2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

  8. Safety and injury profile of conducted electrical weapons used by law enforcement officers against criminal suspects.

    Science.gov (United States)

    Bozeman, William P; Hauda, William E; Heck, Joseph J; Graham, Derrel D; Martin, Brian P; Winslow, James E

    2009-04-01

    Conducted electrical weapons such as the Taser are commonly used by law enforcement agencies. The safety of these weapons has been the subject of scrutiny and controversy; previous controlled studies in animals and healthy humans may not accurately reflect the risks of conducted electrical weapons used in actual conditions. We seek to determine the safety and injury profile of conducted electrical weapons used against criminal suspects in a field setting. This prospective, multicenter, observational trial tracked a consecutive case series of all conducted electrical weapon uses against criminal suspects at 6 US law enforcement agencies. Mandatory review of each conducted electrical weapon use incorporated physician review of police and medical records. Injuries were classified as mild, moderate, or severe according to a priori definitions. The primary outcome was a composite of moderate and severe injuries, termed significant injuries. Conducted electrical weapons were used against 1,201 subjects during 36 months. One thousand one hundred twenty-five subjects (94%) were men; the median age was 30 years (range 13 to 80 years). Mild or no injuries were observed after conducted electrical weapon use in 1,198 subjects (99.75%; 95% confidence interval 99.3% to 99.9%). Of mild injuries, 83% were superficial puncture wounds from conducted electrical weapon probes. Significant injuries occurred in 3 subjects (0.25%; 95% confidence interval 0.07% to 0.7%), including 2 intracranial injuries from falls and 1 case of rhabdomyolysis. Two subjects died in police custody; medical examiners did not find conducted electrical weapon use to be causal or contributory in either case. To our knowledge, these findings represent the first large, independent, multicenter study of conducted electrical weapon injury epidemiology and suggest that more than 99% of subjects do not experience significant injuries after conducted electrical weapon use.

  9. The electrical conductivity of a weakly non-ideal, dense plasma

    NARCIS (Netherlands)

    Rosado, R.J.; Leclair, J.; Schram, D.C.

    1977-01-01

    The electrical conductance of a non-ideal plasma was measured and compared with Spitzer's formula for ideal plasmas and a correction to this formula proposed by Rovinskii. The measured conductance proved to agree better with the Spitzer result

  10. Application of Electromagnetic Induction to Monitor Changes in Soil Electrical Conductivity Profiles in Arid Agriculture

    KAUST Repository

    Jadoon, K.Z.; McCabe, Matthew; Moghadas, D.

    2015-01-01

    In this research, multi-configuration electromagnetic induction (EMI) measurements were conducted in a corn field to estimate variation in soil electrical conductivity profiles in the roots zone. Electromagnetic forward model based on the full

  11. Hysteresis in the relation between moisture uptake and electrical conductivity in neat epoxy

    KAUST Repository

    Lubineau, Gilles; Sulaimani, Anwar Ali; El Yagoubi, Jalal; Mulle, Matthieu; Verdu, Jacques

    2017-01-01

    Monitoring changes in electrical conductivity is a simple way to assess the water uptake from environmental moisture in polymers. However, the relation between water uptake and changes in conductivity is not fully understood. We monitored changes

  12. Frequency and voltage dependent profile of dielectric properties, electric modulus and ac electrical conductivity in the PrBaCoO nanofiber capacitors

    Directory of Open Access Journals (Sweden)

    S. Demirezen

    Full Text Available In this study, praseodymium barium cobalt oxide nanofiber interfacial layer was sandwiched between Au and n-Si. Frequency and voltage dependence of ε′, ε′, tanδ, electric modulus (M′ and M″ and σac of PrBaCoO nanofiber capacitor have been investigated by using impedance spectroscopy method. The obtained experimental results show that the values of ε′, ε′, tanδ, M′, M″ and σac of the PrBaCoO nanofiber capacitor are strongly dependent on frequency of applied bias voltage. The values of ε′, ε″ and tanδ show a steep decrease with increasing frequency for each forward bias voltage, whereas the values of σac and the electric modulus increase with increasing frequency. The high dispersion in ε′ and ε″ values at low frequencies may be attributed to the Maxwell–Wagner and space charge polarization. The high values of ε′ may be due to the interfacial effects within the material, PrBaCoO nanofibers interfacial layer and electron effect. The values of M′ and M″ reach a maximum constant value corresponding to M∞ ≈ 1/ε∞ due to the relaxation process at high frequencies, but both the values of M′ and M″ approach almost to zero at low frequencies. The changes in the dielectric and electrical properties with frequency can be also attributed to the existence of Nss and Rs of the capacitors. As a result, the change in the ε′, ε″, tanδ, M′, M″ and ac electric conductivity (σac is a result of restructuring and reordering of charges at the PrBaCoO/n-Si interface under an external electric field or voltage and interface polarization. Keywords: Thin films, Electrical properties, Interface/interphase

  13. Microbial Activity Influences Electrical Conductivity of Biofilm Anode

    Science.gov (United States)

    This study assessed the conductivity of a Geobacter-enriched biofilm anode along with biofilm activity in a microbial electrochemical cell (MxC) equipped with two gold anodes (25 mM acetate medium), as different proton gradients were built throughout the biofilm. There was no pH ...

  14. Electrically conductive bulk composites through a contact-connected aggregate.

    Directory of Open Access Journals (Sweden)

    Ahsan I Nawroj

    Full Text Available This paper introduces a concept that allows the creation of low-resistance composites using a network of compliant conductive aggregate units, connected through contact, embedded within the composite. Due to the straight-forward fabrication method of the aggregate, conductive composites can be created in nearly arbitrary shapes and sizes, with a lower bound near the length scale of the conductive cell used in the aggregate. The described instantiation involves aggregate cells that are approximately spherical copper coils-of-coils within a polymeric matrix, but the concept can be implemented with a wide range of conductor elements, cell geometries, and matrix materials due to its lack of reliance on specific material chemistries. The aggregate cell network provides a conductive pathway that can have orders of magnitude lower resistance than that of the matrix material--from 10(12 ohm-cm (approx. for pure silicone rubber to as low as 1 ohm-cm for the silicone/copper composite at room temperature for the presented example. After describing the basic concept and key factors involved in its success, three methods of implementing the aggregate into a matrix are then addressed--unjammed packing, jammed packing, and pre-stressed jammed packing--with an analysis of the tradeoffs between increased stiffness and improved resistivity.

  15. Electrical conduction mechanism in GeSeSb chalcogenide glasses

    Indian Academy of Sciences (India)

    by melt quenching has been determined at different temperatures in bulk through the I–V characteristic curves ... DC conductivity; chalcogenide glass; Sb–Se bonding; Poole–Frenkel mechanism .... measurements were taken at room temperature as well as ele- .... age across the sample was continuued, the induced thermal.

  16. NONLINEAR DYNAMO IN A ROTATING ELECTRICALLY CONDUCTING FLUID

    Directory of Open Access Journals (Sweden)

    M. I. Kopp

    2017-05-01

    Full Text Available We found a new large-scale instability, which arises in the rotating conductive fluid with small-scale turbulence. Turbulence is generated by small-scale external force with a low Reynolds number. The theory is built simply by the method of multiscale asymptotic expansions. Nonlinear equations for vortex and magnetic perturbations obtained in the third order for small Reynolds number. It is shown that the combined effects of the Coriolis force and the small external forces in a rotating conducting fluid possible large-scale instability. The large-scale increments of the instability, correspond to generation as the vortex and magnetic disturbances. This type of instability is classified as hydrodynamic and MHD alpha-effect. We studied the stationary regimes of nonlinear equations of magneto-vortex dynamo. In the limit of weakly conducting fluid found stationary solutions in the form of helical kinks. In the limit of high conductivity fluid was obtained stationary solutions in the form of nonlinear periodic waves and kinks.

  17. Microscopic electrical conductivity of nanodiamonds after thermal and plasma treatments

    Czech Academy of Sciences Publication Activity Database

    Čermák, Jan; Kozak, Halyna; Stehlík, Štěpán; Švrček, V.; Pichot, V.; Spitzer, D.; Kromka, Alexander; Rezek, Bohuslav

    2016-01-01

    Roč. 1, č. 16 (2016), s. 1105-1111 ISSN 2059-8521 R&D Projects: GA ČR GA15-01809S Institutional support: RVO:68378271 Keywords : atomic force microscopy * conductive AFM * diamond * nanoparticles * plasma Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. Electrical conductivity of molten SnCl{sub 2} at temperature as high as 1314 K

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, Alexander B.; Potapov, Alexei M. [Ural Branch of RAS, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry

    2015-07-01

    The electrical conductivity of molten SnCl{sub 2} was measured in a wide temperature range (ΔT=763 K), from 551 K to temperature as high as 1314 K, that is, 391 above the boiling point of the salt. The specific electrical conductance was found to reach its maximum at 1143 K, after that it decreases with the temperature rising.

  19. Electrical conductivity of molten SnCl2 at temperature as high as 1314 K

    International Nuclear Information System (INIS)

    Salyulev, Alexander B.; Potapov, Alexei M.

    2015-01-01

    The electrical conductivity of molten SnCl 2 was measured in a wide temperature range (ΔT=763 K), from 551 K to temperature as high as 1314 K, that is, 391 above the boiling point of the salt. The specific electrical conductance was found to reach its maximum at 1143 K, after that it decreases with the temperature rising.

  20. Soil permittivity response to bulk electrical conductivity for selected soil water sensors

    Science.gov (United States)

    Bulk electrical conductivity can dominate the low frequency dielectric loss spectrum in soils, masking changes in the real permittivity and causing errors in estimated water content. We examined the dependence of measured apparent permittivity (Ka) on bulk electrical conductivity in contrasting soil...

  1. Influence of prehistory of polymer samples on radiation electric conductivity induced by ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Aleksanina, O S; Sichkar' , V P; Vajsberg, S Eh [Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR)

    1984-05-01

    Radiation electric conductivity of PS films prepared from solutions in various solvents at various initial concentrations and temperatures and various power of absorbed dose (..gamma..-radiation of /sup 60/Co) has been measured. The results are compared with the change of density of films and existing theoretical concepts of the role of microvoids and free volume in electrical conductivity of a polymer.

  2. Influence of prehistory of polymer samples on radiation electric conductivity induced by ionizing radiation

    International Nuclear Information System (INIS)

    Aleksanina, O.S.; Sichkar', V.P.; Vajsberg, S.Eh.

    1984-01-01

    Radiation electric conductivity of PS films prepared from solutions in various solvents at various initial concentrations and temperatures and various power of absorbed dose (γ-radiation of 60 Co) has been measured. The results are compared with the change of density of films and existing theoretical concepts of the role of microvoids and free volume in electrical conductivity of a polymer

  3. Electrical conductivity of platinum-implanted polymethylmethacrylate nanocomposite

    Science.gov (United States)

    Salvadori, M. C.; Teixeira, F. S.; Cattani, M.; Brown, I. G.

    2011-12-01

    Platinum/polymethylmethacrylate (Pt/PMMA) nanocomposite material was formed by low energy ion implantation of Pt into PMMA, and the transition from insulating to conducting phase was explored. In situ resistivity measurements were performed as the implantation proceeded, and transmission electron microscopy was used for direct visualization of Pt nanoparticles. Numerical simulation was carried out using the TRIDYN computer code to calculate the expected depth profiles of the implanted platinum. The maximum dose for which the Pt/PMMA system remains an insulator/conductor composite was found to be ϕ0 = 1.6 × 1016 cm-2, the percolation dose was 0.5 × 1016 cm-2, and the critical exponent was t = 1.46, indicating that the conductivity is due only to percolation. The results are compared with previously reported results for a Au/PMMA composite.

  4. The bedrock electrical conductivity structure of Northern Ireland

    OpenAIRE

    Beamish, David

    2013-01-01

    An airborne geophysical survey of the whole of Northern Ireland has provided over 4.8 M estimates of the bedrock conductivity over the wide range of geological formations present. This study investigates how such data can be used to provide additional knowledge in relation to existing digital geological map information. A by-product of the analysis is a simplification of the spatially aggregated information obtained in such surveys. The methodology used is a GIS-based attribution of the condu...

  5. Pump effect of a capillary discharge in electrically conductive liquids

    Czech Academy of Sciences Publication Activity Database

    De Baerdemaeker, F.; Šimek, Milan; Leys, C.; Verstraete, W.

    2007-01-01

    Roč. 27, č. 4 (2007), s. 473-485 ISSN 0272-4324 R&D Projects: GA AV ČR IAA1043403 Institutional research plan: CEZ:AV0Z20430508 Keywords : water * conductive * capillary * AC discharge * pump Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.747, year: 2007 http://www.springerlink.com/content/w802073563282272/fulltext.pdf

  6. Enhancement of electrical conductivity in the Gum Arabica complex

    International Nuclear Information System (INIS)

    Pradhan, Sourav S.; Sarkar, A.

    2009-01-01

    Gum Arabica is a natural biopolymer obtained from plant Acacia Arabica. In this present study the electro-active nature of its complex has been investigated. The complexes were developed using pure Gum Arabica and pure Citric acid by the sol-gel process. The scope of complex formation has been investigated and their natures were examined experimentally. The experiments which were carried out in this work are namely d.c V-I characteristics, d.c Arrhenius, ion transference number measurement, UV-VIS and IR photo-absorption. Solid specimen of the complex at various concentration of Citric acid has been developed for d.c experiments and adequate specimens were also developed for UV-VIS experiment. The result of d.c V-I characteristics on specimens at different Citric acid concentrations shows that d.c conductivity increases with concentration of the acid. The said enhancement is observed to be about 100 times that of pure hosts. The ion transference number measurement shows that the total conductivity increases with external acid concentration of which d.c conductivity enhance many times compared to that of ionic part. The result from d.c Arrhenius study shows that electro-thermal activation energy decreases with increasing acid concentration leading to enhancement of electronic conductivity of the complex. The result of UV-VIS study confirms the formation of the acid complex of Gum Arabica. The nature of photo-absorption indicates very clearly that main absorption region shows gradual shifts towards longer wavelength with increase of acid concentration. The result of FTIR absorption shows the structural concepts of electro-activity and complex formation indication of pure Gum Arabica. The overall analysis shows that the electro-activity of the mentioned biopolymer may be tailored.

  7. Electric conductance of films prepared from polymeric composite nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Hain, J.; Pich, A.; Adler, H. J.; Rais, David; Nešpůrek, Stanislav

    2008-01-01

    Roč. 268, č. 1 (2008), s. 61-65 ISSN 1022-1360. [Microsymposium on Advanced Polymer Materials for Photonics and Electronics /47./. Prague, 15.07.2007-19.07.2007] R&D Projects: GA AV ČR KAN400720701; GA MŠk OC 138 Institutional research plan: CEZ:AV0Z40500505 Keywords : coatings * composites * conducting polymers Subject RIV: BM - Solid Matter Physics ; Magnetism

  8. Electrical properties of conducting loads produced from polyaniline deposited in natural fibers and nanoclays

    International Nuclear Information System (INIS)

    Kosenhoski, Dirlaine; Saade, Wesley; Pinto, Camila P.; Becker, Daniela; Dalmolin, Carla; Pachekoski, Wagner M.

    2015-01-01

    Conducting polymers are known for their excellent magnetic and electrical properties, but they still are an expensive and limited choice to their use as a conducting load for composite materials. An alternative to optimize the electrical conductivity of polymeric composites is the deposition of a conducting polymer on materials already used as loads, as the deposition on natural fibers or the encapsulation of polymeric chains in the voids of host structures. In this work, bananastem fiber and montmorillonite nanoclay (MMT) were used as host structures for polyaniline synthesis in order to produce conducting loads. Samples were characterized by FT-IR and X-Rays Diffraction in order to confirm the formation of polyanilina / bananastem fibers or polyanilina / nanoclays loads. Influence on the electrical properties of the composites were evaluated by Electrochemical Impedance Spectroscopy (EIS), showing the maintenance of the electric conductivity of polyaniline and its potential use as a load for the formation of conducting composites. (author)

  9. Differential and directional effects of perfusion on electrical and thermal conductivities in liver.

    Science.gov (United States)

    Podhajsky, Ronald J; Yi, Ming; Mahajan, Roop L

    2009-01-01

    Two different measurement probes--an electrical probe and a thermal conductivity probe--were designed, fabricated, calibrated, and used in experimental studies on a pig liver model that was designed to control perfusion rates. These probes were fabricated by photolithography and mounted in 1.5-mm diameter catheters. We measured the local impedance and thermal conductivity, respectively, of the artificially perfused liver at different flow rates and, by rotating the probes, in different directions. The results show that both the local electrical conductivity and the thermal conductivity varied location to location, that thermal conductivity increased with decreased distance to large blood vessels, and that significant directional differences exist in both electrical and thermal conductivities. Measurements at different perfusion rates demonstrated that both the local electrical and local thermal conductivities increased linearly with the square root of perfusion rate. These correlations may be of great value to many energy-based biomedical applications.

  10. Structural and electrical properties of conducting diamond nanowires.

    Science.gov (United States)

    Sankaran, Kamatchi Jothiramalingam; Lin, Yen-Fu; Jian, Wen-Bin; Chen, Huang-Chin; Panda, Kalpataru; Sundaravel, Balakrishnan; Dong, Chung-Li; Tai, Nyan-Hwa; Lin, I-Nan

    2013-02-01

    Conducting diamond nanowires (DNWs) films have been synthesized by N₂-based microwave plasma enhanced chemical vapor deposition. The incorporation of nitrogen into DNWs films is examined by C 1s X-ray photoemission spectroscopy and morphology of DNWs is discerned using field-emission scanning electron microscopy and transmission electron microscopy (TEM). The electron diffraction pattern, the visible-Raman spectroscopy, and the near-edge X-ray absorption fine structure spectroscopy display the coexistence of sp³ diamond and sp² graphitic phases in DNWs films. In addition, the microstructure investigation, carried out by high-resolution TEM with Fourier transformed pattern, indicates diamond grains and graphitic grain boundaries on surface of DNWs. The same result is confirmed by scanning tunneling microscopy and scanning tunneling spectroscopy (STS). Furthermore, the STS spectra of current-voltage curves discover a high tunneling current at the position near the graphitic grain boundaries. These highly conducting regimes of grain boundaries form effective electron paths and its transport mechanism is explained by the three-dimensional (3D) Mott's variable range hopping in a wide temperature from 300 to 20 K. Interestingly, this specific feature of high conducting grain boundaries of DNWs demonstrates a high efficiency in field emission and pave a way to the next generation of high-definition flat panel displays or plasma devices.

  11. Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

    International Nuclear Information System (INIS)

    Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

    2013-01-01

    Highlights: •The electrical conductivity of PPLP in LN 2 was successfully measured. •Based on the measured value of PPLP, DC field analysis was performed. •The electric field distribution was altered according to the DC applying stages. •The maximum electric field was observed during polarity reversal situation. •DC field analysis is important to determine the optimum design of DC HTS devices. -- Abstract: High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN 2 ). Electrical conductivity of PPLP in LN 2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN 2 were presented in this paper. Based on the experimental works, DC electric field distribution of

  12. Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions. PMID:21505445

  13. Reversible temperature regulation of electrical and thermal conductivity using liquid-solid phase transitions.

    Science.gov (United States)

    Zheng, Ruiting; Gao, Jinwei; Wang, Jianjian; Chen, Gang

    2011-01-01

    Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce a general strategy to achieve large contrasts in electrical and thermal conductivities using first-order phase transitions in percolated composite materials. Internal stress generated during a phase transition modulates the electrical and thermal contact resistances, leading to large contrasts in the electrical and thermal conductivities at the phase transition temperature. With graphite/hexadecane suspensions, the electrical conductivity changes 2 orders of magnitude and the thermal conductivity varies up to 3.2 times near 18 °C. The generality of the approach is also demonstrated in other materials such as graphite/water and carbon nanotube/hexadecane suspensions.

  14. Impurity effects on electrical conductivity of doped bilayer graphene in the presence of a bias voltage

    International Nuclear Information System (INIS)

    Lotfi, E; Rezania, H; Arghavaninia, B; Yarmohammadi, M

    2016-01-01

    We address the electrical conductivity of bilayer graphene as a function of temperature, impurity concentration, and scattering strength in the presence of a finite bias voltage at finite doping, beginning with a description of the tight-binding model using the linear response theory and Green’s function approach. Our results show a linear behavior at high doping for the case of high bias voltage. The effects of electron doping on the electrical conductivity have been studied via changing the electronic chemical potential. We also discuss and analyze how the bias voltage affects the temperature behavior of the electrical conductivity. Finally, we study the behavior of the electrical conductivity as a function of the impurity concentration and scattering strength for different bias voltages and chemical potentials respectively. The electrical conductivity is found to be monotonically decreasing with impurity scattering strength due to the increased scattering among electrons at higher impurity scattering strength. (paper)

  15. Hopping transport and electrical conductivity in one-dimensional systems with off-diagonal disorder

    International Nuclear Information System (INIS)

    Ma Songshan; Xu Hui; Li Yanfeng; Song Zhaoquan

    2007-01-01

    In this paper, we present a model to describe hopping transport and electrical conductivity of one-dimensional systems with off-diagonal disorder, in which electrons are transported via hopping between localized states. We find that off-diagonal disorder leads to delocalization and drastically enhances the electrical conductivity of systems. The model also quantitatively explains the temperature and electrical field dependence of the conductivity in one-dimensional systems with off-diagonal disorder. In addition, we also show the dependence of the conductivity on the strength of off-diagonal disorder

  16. Effect of neutron flux on the frequency dependencies of electrical conductivity of silicon nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Huseynov, E.; Garibli, A., E-mail: elchin.huse@yahoo.com [National Nuclear Research Center, Department of Nanotechnology and Radiation Material Science, 1073, Inshaatchilar pr. 4, Baku (Azerbaijan)

    2016-11-01

    It has been reviewed the frequency dependencies of electrical conductivity of nanoparticles affected by neutron flux at different times and initial state, at various constant temperatures such as 100, 200, 300 and 400 K. Measurements have been carried out at each temperature at the different 97 values of frequency in the 1 Hz - 1 MHz range. From interdependence between real and imaginary parts of electrical conductivity it has been determined the type of conductivity. Moreover, in the work it is given the mechanism of electrical conductivity according to the obtained results. (Author)

  17. A novel thick-film electrical conductivity sensor suitable for liquid and soil conductivity measurements

    OpenAIRE

    Atkinson, John; Sophocleous, Marios

    2015-01-01

    Results are reported from an initial evaluation of a novel conductivity sensor that could be incorporated onto a multi-element thick film (screen printed) sensor array designed for soil and water analysis. The new sensor exhibits a repeatable cell constant over a wide range of conductivities and is currently performing very well in an investigation of soil structural properties where its output is being correlated with soil water content in a study of different soil porosities.

  18. Electrical conductivity enhancement of polyethersulfone (PES) by ion implantation

    International Nuclear Information System (INIS)

    Bridwell, L.B.; Giedd, R.E.; Wang Yongqiang; Mohite, S.S.; Jahnke, T.; Brown, I.M.

    1991-01-01

    Amorphous polyethersulfone (PES) films have been implanted with a variety of ions (He, B, C, N and As) at a bombarding energy of 50 keV in the dose range 10 16 -10 17 ions/cm 2 . Surface resistance as a function of dose indicates a saturation effect with a significant difference between He and the other ions used. ESR line shapes in the He implanted samples changed from a mixed Gaussian/Lorentzian to a pure Lorentzian and narrowed with increasing dose. Temperature dependent resistivity indicates an electron hopping mechanism for conduction. Infrared results indicate cross-linking or self-cyclization occurred for all implanted ions with further destruction in the case of As. (orig.)

  19. Doping dependence of electrical and thermal conductivity of nanoscale polyaniline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jin Jiezhu; Wang Qing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Haque, M A [Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    2010-05-26

    We performed simultaneous characterization of electrical and thermal conductivity of 55 nm thick polyaniline (PANI) thin films doped with different levels of camphor sulfonic acids (CSAs). The effect of the doping level is more pronounced on electrical conductivity than on thermal conductivity of PANIs, thereby greatly affecting their ratio that determines the thermoelectric efficiency. At the 60% (the molar ratio of CSA to phenyl-N repeat unit of PANI) doping level, PANI exhibited the maximum electrical and thermal conductivity due to the formation of mostly delocalized structures. Whereas polarons are the charge carriers responsible for the electrical conduction, phonons are believed to play a dominant role in the heat conduction in nanoscale doped PANI thin films.

  20. Nanoionics phenomenon in proton-conducting oxide: Effect of dispersion of nanosize platinum particles on electrical conduction properties

    Directory of Open Access Journals (Sweden)

    Hiroshige Matsumoto et al

    2007-01-01

    Full Text Available High-temperature proton conductors are oxides in which low-valence cations are doped as electron acceptors; the incorporation of water molecules into the oxides results in the formation of protonic defects that act as charge carriers. Since the protons thus formed are in equilibrium with other electronic defects, electrons and holes, the oxides possibly have different proton-conduction properties at and near boundaries when they are in contact with another phase. In this paper, we present our recent experimental observation of a marked change in the electrical properties of a proton conductor upon the dispersal of fine platinum particles in the oxide. First, the material shows extremely low electrical conductivity in comparison with the original proton-conducting perovskite. Second, there was a threshold amount of platinum at which such a drop in conductivity occurred. A percolation model is employed to explain these experimental results; the fine platinum particles dispersed in the proton-conducting oxide wears highly resistive skin that is formed due to shifts in defect equilibriums, which prevents ionic/electronic conduction. The experiments suggest that the ion-conducting properties of oxides can be varied by introducing interfaces at a certain density; nanoionics is a key to yielding enhanced and/or controlled ionic conduction in solids.

  1. Simultaneous measurements of thermal conductivity and electrical conductivity of micro-machined Silicon films

    International Nuclear Information System (INIS)

    Hagino, H; Kawahara, Y; Goto, A; Miyazaki, K

    2012-01-01

    The in-plane effective thermal conductivity of free-standing Si thin films with periodic micropores was measured at -100 to 0 °C. The Si thin films with micropores were prepared from silicon-on-insulator (SOI) wafers by standard microfabrication processes. The dimensions of the free-standing Si thin films were 200μm×150μm×2 μm, with staggered 4 μm pores having an average pitch of 4 mm. The Si thin film serves both as a heater and thermometer. The average temperature rise of the thin film is a function of its in-plane thermal conductivity. The effective thermal conductivity was calculated using a simple one-dimensional heat conduction model. The measured thermal conductivity was much lower than that expected based on classical model evaluations. A significant phonon size effect was observed even in the microsized structures, and the mean free path for phonons is very long even at the room temperature.

  2. Exchange of transverse plasmons and electrical conductivity of neutron star cores

    International Nuclear Information System (INIS)

    Shternin, P. S.

    2008-01-01

    We study the electrical conductivity in magnetized neutron star cores produced by collisions between charged particles. We take into account the ordinary exchange of longitudinal plasmons and the exchange of transverse plasmons in collisions between particles. The exchange of transverse plasmons is important for collisions between relativistic particles, but it has been disregarded previously when calculating the electrical conductivity. We show that taking this exchange into account changes the electrical conductivity, including its temperature dependence (thus, for example, the temperature dependence of the electrical resistivity along the magnetic field in the low-temperature limit takes the form R parallel ∝ T 5/3 instead of the standard dependence R parallel ∝ T 2 for degenerate Fermi systems). We briefly describe the effect of possible neutron and proton superfluidity in neutron star cores on the electrical conductivity and discuss various scenarios for the evolution of neutron star magnetic fields

  3. The effect of radiation induced electrical conductivity (RIC) on the thermal conductivity

    International Nuclear Information System (INIS)

    White, D.P.

    1993-01-01

    Microwave heating of plasmas in fusion reactors requires the development of microwave windows through which the microwaves can pass without great losses. The degradation of the thermal conductivity of alumina in a radiation environment is an important consideration in reliability studies of these microwave windows. Several recent papers have addressed this question at higher temperatures and at low temperatures. The current paper extends the low temperature calculations to determine the effect of phonon-electron scattering on the thermal conductivity at 77 K due to RIC. These low temperature calculations are of interest because the successful application of high power (>1 MW) windows for electron cyclotron heating systems in fusion reactors will most likely require cryogenic cooling to take advantage of the low loss tangent and higher thermal conductivity of candidate window materials at these temperatures

  4. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    International Nuclear Information System (INIS)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Beevi, Akbar Sait Hameedha; Priya, Radhakrishnan Jeeva; Maduraiveeran, Govindhan

    2015-01-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices. (paper)

  5. DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications

    International Nuclear Information System (INIS)

    Katoh, Y.; Kondo, S.; Snead, L.L.

    2009-01-01

    High purity chemically vapor-deposited silicon carbide (SiC) and 2D continuous SiC fiber, chemically vapor-infiltrated SiC matrix composites with pyrocarbon interphases were examined. Specifically, temperature dependent (RT to 800 deg. C) electrical conductivity and the influence of neutron irradiation were measured. The influence of neutron irradiation on electrical properties appeared very strong for the SiC of this study, typically resulting in orders lower ambient conductivity and steeper temperature dependency of this conductivity. For the 2D composites, through-thickness (normal to the fiber axis') electrical conductivity was dominated by bypass conduction via interphase network at relatively low temperatures, whereas conduction through SiC constituents dominated at higher temperatures. Through-thickness electrical conductivity of neutron-irradiated 2D SiC composites with thin PyC interphase, currently envisioned for flow channel insert application, will likely in the order of 10 S/m at the appropriate operating temperature. Mechanisms of electrical conduction in the composites and irradiation-induced modification of electrical conductivity of the composites and their constituents are discussed.

  6. Properties of grafted polymer metal complexes as ion exchangers and its electrical conductivity

    International Nuclear Information System (INIS)

    El-Arnaouty, M.B.; Abdel Ghaffar, A.M.; Eid, M.

    2011-01-01

    The polyelectrolyte has been prepared as a potential proton exchanger polymer by grafting of acrylic acid/acrylamide and acrylic acid/acrylonitrile comonomer onto low density polyethylene film via gamma radiation. The influence of grafting percent on the electrical conductivity was studied. The resulting polymers were then characterized by evaluating their physico-chemical properties such as ion exchange capacity, and electrical conductivity as a function of grafting yield. The grafted films at different compositions was characterized by FTIR, TGA and SEM. The ion exchange capacity (IEC) of the grafted film at grafting % (191) and monomer concentration ratio 50:50 for (LDPE-g-AAc/AAm) was found to be more than that for (LDPE-g-AAc/AN). The electrical conductivity was found to be greatly affected by the comonomer composition where it increased as the degree of grafting increased for all grafted films. After alkaline treatment with 3% KOH, the electrical conductivity of the grafted films found to be increased. The presence of potassium as counter ion maximized the electrical conductivity of the grafted films. The electrical conductivity of Cu-membrane complexes was higher than that of both Co and Ni complexes. The electrical conductivity increases by increasing both Cu ions content and temperature

  7. Simplified Calculation of the Electrical Conductivity of Composites with Carbon Nanotubes

    Science.gov (United States)

    Ivanov, S. G.; Aniskevich, A.; Kulakov, V.

    2018-03-01

    The electrical conductivity of two groups of polymer nanocomposites filled with the same NC7000 carbon nanotubes (CNTs) beyond the percolation threshold is described with the help of simple formulas. Different manufacturing process of the nanocomposites led to different CNT network structures, and, as a consequence, their electrical conductivity, at the same CNT volume, differed by two orders of magnitude. The relation between the electrical conductivity and the volume content of CNTs of the first group of composites (with a higher electrical conductivity) is described assuming that the CNT network structure is close to a statistically homogeneous one. The formula for this case, derived on the basis of a self-consistent model, includes only two parameters: the effective longitudinal electrical conductivity of CNT and the percolation threshold (the critical value of CNT volume content). These parameters were determined from two experimental points of electrical conductivity as a function of the volume fraction of CNTs. The second group of nanocomposites had a pronounced agglomerative structure, which was confirmed by microscopy data. To describe the low electrical conductivity of this group of nanocomposites, a formula based on known models of micromechanics is proposed. Two parameters of this formula were determined from experimental data of the first group, but the other two — of the second group of nanocomposites. A comparison of calculation and experimental relations confirmed the practical expediency of using the approach described.

  8. Impact of radiofrequency ablation geometry on electrical conduction

    Science.gov (United States)

    Rivas, Rhiana N.; Lye, Theresa H.; Hendon, Christine P.

    2018-02-01

    The gold standard of current treatment for atrial fibrillation is radiofrequency ablation (RFA). Single RFA procedures have low long-term, single-procedure success rates, which can be attributed to factors including inability to measure and visualize lesion depth in real time and incomplete knowledge of how atrial fibrillation manifests and persists. One way to address this problem is to develop a heart model that accurately fits lesion dimensions and depth using OCT to extract structural information. Twenty-three lesions of varying transmurality in left and right swine atrial tissue have been imaged with a Thorlabs OCT system with 6.5-micron axial resolution and a custom Ultra High Resolution system with 2.5-micron axial resolution. The boundaries of the ablation lesions were identified by the appearance of the birefringence artifact to identify areas of un-ablated tissue, as well as by changes to depth penetration and structural features, including decreased contrast between the endocardium and myocardium and disappearance of collagen fibers within the ablation lesion. Using these features, the lateral positions of the lesion boundaries were identified. An algorithm that fit ellipses to the lesion contours modeled the ablation geometry in depth. Lesion dimensions and shape were confirmed by comparison with trichrome histological processing. Finite-element models were fitted with these parameters and electrophysiological simulations were run with the Continuity 6 package. Next steps include correlating lesion geometry to conduction velocity, and including further tissue complexity such as varying tissue composition and fiber orientation. Additional models of linear lesions with gaps and adjacent lesions created with non-perpendicular contact will be created. This work will provide insight into how lesion geometry, tissue composition, and fiber organization impact electrophysiological propagation.

  9. Electrically conductive carbon fibre-reinforced composite for aircraft lightning strike protection

    Science.gov (United States)

    Katunin, Andrzej; Krukiewicz, Katarzyna; Turczyn, Roman; Sul, Przemysław; Bilewicz, Marcin

    2017-05-01

    Aircraft elements, especially elements of exterior fuselage, are subjected to damage caused by lightning strikes. Due to the fact that these elements are manufactured from polymeric composites in modern aircraft, and thus, they cannot conduct electrical charges, the lightning strikes cause burnouts in composite structures. Therefore, the effective lightning strike protection for such structures is highly desired. The solution presented in this paper is based on application of organic conductive fillers in the form of intrinsically conducting polymers and carbon fabric in order to ensure electrical conductivity of whole composite and simultaneously retain superior mechanical properties. The presented studies cover synthesis and manufacturing of the electrically conductive composite as well as its characterization with respect to mechanical and electrical properties. The performed studies indicate that the proposed material can be potentially considered as a constructional material for aircraft industry, which characterizes by good operational properties and low cost of manufacturing with respect to current lightning strike protection materials solutions.

  10. Music through the skin—simple demonstration of human electrical conductivity

    Science.gov (United States)

    Vollmer, M.; Möllmann, K. P.

    2016-05-01

    The conduction of electricity is an important topic for any basic physics course. Issues of safety often results in teacher demonstration experiments in front of the class or in extremely simple though—for students—not really fascinating (not to say boring) hands on activities for everybody using 1.5 V batteries, cables and light bulbs etc. Here we briefly review some basic facts about conduction of electricity through the human body and report a simple, safe, and awe inspiring electrical conduction experiment which can be performed with little preparation by a teacher involving the whole class of say 20 students.

  11. Experimental study of electric conductivity, density and viscosity of Wood's alloy

    International Nuclear Information System (INIS)

    Kazandzhan, B.I.; Matveev, V.M.; Savich, T.B.; Umarov, A.M.

    1989-01-01

    Electric conductivity, density and kinematic viscosity of commercially pure Wood's alloy are obtained in a wide temperature range. Electric conductivity and density are investigated from the room temperature to 1000 K. Measurements of kinematic viscosity are carried out from 372 to 1000 K by means of torsional vibrations method using informatiom computer system permitting to automate data acquisition and processing and to increase the measurement accuracy. On the basis of analysis the character of electric conductivity and kinematic viscosity polyterms Wood's alloy liquidus and solidus temperatures are estimated

  12. Damage detection and conductivity evolution in carbon nanofiber epoxy via electrical impedance tomography

    International Nuclear Information System (INIS)

    Tallman, T N; Wang, K W; Gungor, S; Bakis, C E

    2014-01-01

    Utilizing electrically conductive nanocomposites for integrated self-sensing and health monitoring is a promising area of structural health monitoring (SHM) research wherein local changes in conductivity coincide with damage. In this research we conduct proof of concept investigations using electrical impedance tomography (EIT) for damage detection by identifying conductivity changes and by imaging conductivity evolution in a carbon nanofiber (CNF) filled epoxy composite. CNF/epoxy is examined because fibrous composites can be manufactured with a CNF/epoxy matrix thereby enabling the entire matrix to become self-sensing. We also study the mechanisms of conductivity evolution in CNF/epoxy through electrical impedance spectroscopy (EIS) testing. The results of these tests indicate that thermal expansion is responsible for conductivity evolution in a CNF/epoxy composite. (paper)

  13. Numerical estimation of the effective electrical conductivity in carbon paper diffusion media

    International Nuclear Information System (INIS)

    Zamel, Nada; Li, Xianguo; Shen, Jun

    2012-01-01

    Highlights: ► Anisotropic effective electrical conductivity of the GDL is estimated numerically. ► The electrical conductivity is a key component in understanding the structure of the GDL. ► Expressions for evaluating the electrical conductivity were proposed. ► The tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively. - Abstract: The transport of electrons through the gas diffusion layer (GDL) of polymer electrolyte membrane (PEM) fuel cells has a significant impact on the optimal design and operation of PEM fuel cells and is directly affected by the anisotropic nature of the carbon paper material. In this study, a three-dimensional reconstruction of the GDL is used to numerically estimate the directional dependent effective electrical conductivity of the layer for various porosity values. The distribution of the fibers in the through-plane direction results in high electrical resistivity; hence, decreasing the overall effective electrical conductivity in this direction. This finding is in agreement with measured experimental data. Further, using the numerical results of this study, two mathematical expressions were proposed for the calculation of the effective electrical conductivity of the carbon paper GDL. Finally, the tortuosity factor was evaluated as 1.7 and 3.4 in the in- and through-plane directions, respectively.

  14. Electrical conductivity of cobalt–titanium substituted SrCaM hexaferrites

    International Nuclear Information System (INIS)

    Eraky, M.R.

    2012-01-01

    A series of polycrystalline M-type hexagonal ferrites with the composition Sr 0.5 Ca 0.5 Co x Ti x Fe 12−2x O 19 (where x=0.0–0.8) were prepared by the conventional ceramic technique. The electrical conductivity has been measured from 300 to 590 K. The dc conductivity, σ dc , exhibited a semiconductor behavior. The negative sign of thermoelectric power coefficient S reveals that all samples are n-type semiconductors. Both σ dc and mobility, μ d , increases with the substitution of Co 2+ and Ti 4+ ions, reach maximum at x=0.4 and start decreasing at x>0.4. Many conduction mechanisms were discussed to explain the electric conduction in the system. It was found that the hopping conduction is the predominant conduction mechanism. For samples with compositional parameter x=0.0 and 0.8, the band conduction mechanism shares in electric conduction beside the hopping process. - Highlights: ► SrCaCoTiM hexaferrites have been prepared by conventional ceramic technique. ► The electrical conductivity exhibited a semiconductor behavior. There is an increase in conductivity up to x=0.4 for Co and Ti substitution. ► The hopping conduction is the predominant conduction mechanism.

  15. Electrical conductivity of short carbon fibers and carbon black-reinforced chloroprene rubber

    International Nuclear Information System (INIS)

    Khoshniat, A. R.; MirAli, M.; Hemmati, M.; Afshar Taromi, F.; Katbab, A.

    2002-01-01

    Elastomers and plastics are intrinsically insulating materials, but by addition of some conductive particles such as conductive carbon black, carbon fibers and metals, they can change to conductive form. Conductivity of these composites are due to formation of the lattices of conductive filler particles in polymer chains. In this report, conductivity of chloroprene rubber filled with carbon black and carbon fibers as a function of temperature and pressure are studied. Electrical conductivity of chloroprene in a function of temperature and pressure are studied. Electrical conductivity of chloroprene in the presence of carbon black with proper mixing conditions increases to the conductivity level of semiconductors and even in the presence of carbon fibers it increases to the level of a conductor material. Meanwhile, the sensitivity of this compound to heat and pressure rises. Thus these composites have found various applications in the manufacture of heat and pressure sensitive sensors

  16. INVESTIGATION OF HEAT CONDUCTION AND SPECIFIC ELECTRIC IMPEDANCE OF POROUS MATERIALS

    Directory of Open Access Journals (Sweden)

    E. S. Golubtsova

    2004-01-01

    Full Text Available In this article there was investigated the influence of porosity and temperature change on heat condition and electrical resistance of porous iron (PZh4M nickel and steel 14X17H2. There are received the adequate equations of regression, establishing connection between heat conduction and electrical resistance of the investigated materials with their porosity and temperature.

  17. The electrical conductivity of CuCrZr alloy after SPD processing

    International Nuclear Information System (INIS)

    Lipińska, M; Bazarnik, P; Lewandowska, M

    2014-01-01

    CuCrZr alloys exhibit very good relation between mechanical properties and electrical conductivity. However, for its use in some advanced applications improvement of mechanical strength while preserving high electrical conducting is required. Therefore, in this work a CuCrZr alloy was subjected to a series of thermo-mechanical treatments, including solution annealing and water quenching, SPD processing (using hydrostatic extrusion and ECAP) as well as aging in order to improve mechanical strength. The influence of these processing procedures on microstructure features and mechanical properties was determined by TEM observation and microhardness measurements, respectively. Electrical conductivity of the samples was measured by four-points method. The results have shown that it is possible to improve mechanical strength while preserving good electrical conductivity by a proper combination of SPD processing and heat treatment

  18. Explaining electric conductivity using the particle-in-a-box model: quantum superposition is the key

    Science.gov (United States)

    Sivanesan, Umaseh; Tsang, Kin; Izmaylov, Artur F.

    2017-12-01

    Most of the textbooks explaining electric conductivity in the context of quantum mechanics provide either incomplete or semi-classical explanations that are not connected with the elementary concepts of quantum mechanics. We illustrate the conduction phenomena using the simplest model system in quantum dynamics, a particle in a box (PIB). To induce the particle dynamics, a linear potential tilting the bottom of the box is introduced, which is equivalent to imposing a constant electric field for a charged particle. Although the PIB model represents a closed system that cannot have a flow of electrons through the system, we consider the oscillatory dynamics of the particle probability density as the analogue of the electric current. Relating the amplitude and other parameters of the particle oscillatory dynamics with the gap between the ground and excited states of the PIB model allows us to demonstrate one of the most basic dependencies of electric conductivity on the valence-conduction band gap of the material.

  19. Electrical conductivity of molten CdCl{sub 2} at temperatures as high as 1474 K

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, Alexander B.; Potapov, Alexei M. [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry

    2016-11-01

    The electrical conductivity of molten CdCl{sub 2} was measured across a wide temperature range (ΔT=628 K), from 846 K to as high as 1474 K, i.e. 241 above the normal boiling point of the salt. In previous studies, a maximum temperature of 1201 K was reached, this being 273 lower than in the present work. The activation energy of electrical conductivity was calculated.

  20. Electrical conductivity of molten CdCl2 at temperatures as high as 1474 K

    International Nuclear Information System (INIS)

    Salyulev, Alexander B.; Potapov, Alexei M.

    2016-01-01

    The electrical conductivity of molten CdCl 2 was measured across a wide temperature range (ΔT=628 K), from 846 K to as high as 1474 K, i.e. 241 above the normal boiling point of the salt. In previous studies, a maximum temperature of 1201 K was reached, this being 273 lower than in the present work. The activation energy of electrical conductivity was calculated.

  1. Electrical conductivity of highly ionized dense hydrogen plasma. 1. Electrical measurements and diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Radtke, R; Guenther, K [Akademie der Wissenschaften der DDR, Berlin. Zentralinstitut fuer Elektronenphysik

    1976-05-11

    A diagnostic technique for the determination of pressure, temperature and its radial distribution, the strength of the electric field and the current of a wall-stabilized pulse hydrogen arc at a pressure of 10 atm and a maximum power of 120 kW/cm arc length is developed.

  2. Experimental and numerical investigation of the effective electrical conductivity of nitrogen-doped graphene nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Mehrali, Mohammad, E-mail: mohamad.mehrali@siswa.um.edu.my [University of Malaya, Department of Mechanical Engineering and Advanced Material Research Centre (Malaysia); Sadeghinezhad, Emad, E-mail: esn802001@yahoo.com [University of Malaya, Department of Mechanical Engineering (Malaysia); Rashidi, Mohammad Mehdi [Tongji University, Shanghai Automotive Wind Tunnel Center (China); Akhiani, Amir Reza; Tahan Latibari, Sara; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis [University of Malaya, Department of Mechanical Engineering and Advanced Material Research Centre (Malaysia)

    2015-06-15

    Electrical conductivity is an important property for technological applications of nanofluids that have not been widely investigated, and few studies have been concerned about the electrical conductivity. In this study, nitrogen-doped graphene (NDG) nanofluids were prepared using the two-step method in an aqueous solution of 0.025 wt% Triton X-100 as a surfactant at several concentrations (0.01, 0.02, 0.04, 0.06 wt%). The electrical conductivity of the aqueous NDG nanofluids showed a linear dependence on the concentration and increased up to 1814.96 % for a loading of 0.06 wt% NDG nanosheet. From the experimental data, empirical models were developed to express the electrical conductivity as functions of temperature and concentration. It was observed that increasing the temperature has much greater effect on electrical conductivity enhancement than increasing the NDG nanosheet loading. Additionally, by considering the electrophoresis of the NDG nanosheets, a straightforward electrical conductivity model is established to modulate and understand the experimental results.

  3. Experimental and numerical investigation of the effective electrical conductivity of nitrogen-doped graphene nanofluids

    Science.gov (United States)

    Mehrali, Mohammad; Sadeghinezhad, Emad; Rashidi, Mohammad Mehdi; Akhiani, Amir Reza; Tahan Latibari, Sara; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis

    2015-06-01

    Electrical conductivity is an important property for technological applications of nanofluids that have not been widely investigated, and few studies have been concerned about the electrical conductivity. In this study, nitrogen-doped graphene (NDG) nanofluids were prepared using the two-step method in an aqueous solution of 0.025 wt% Triton X-100 as a surfactant at several concentrations (0.01, 0.02, 0.04, 0.06 wt%). The electrical conductivity of the aqueous NDG nanofluids showed a linear dependence on the concentration and increased up to 1814.96 % for a loading of 0.06 wt% NDG nanosheet. From the experimental data, empirical models were developed to express the electrical conductivity as functions of temperature and concentration. It was observed that increasing the temperature has much greater effect on electrical conductivity enhancement than increasing the NDG nanosheet loading. Additionally, by considering the electrophoresis of the NDG nanosheets, a straightforward electrical conductivity model is established to modulate and understand the experimental results.

  4. Experimental and numerical investigation of the effective electrical conductivity of nitrogen-doped graphene nanofluids

    International Nuclear Information System (INIS)

    Mehrali, Mohammad; Sadeghinezhad, Emad; Rashidi, Mohammad Mehdi; Akhiani, Amir Reza; Tahan Latibari, Sara; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis

    2015-01-01

    Electrical conductivity is an important property for technological applications of nanofluids that have not been widely investigated, and few studies have been concerned about the electrical conductivity. In this study, nitrogen-doped graphene (NDG) nanofluids were prepared using the two-step method in an aqueous solution of 0.025 wt% Triton X-100 as a surfactant at several concentrations (0.01, 0.02, 0.04, 0.06 wt%). The electrical conductivity of the aqueous NDG nanofluids showed a linear dependence on the concentration and increased up to 1814.96 % for a loading of 0.06 wt% NDG nanosheet. From the experimental data, empirical models were developed to express the electrical conductivity as functions of temperature and concentration. It was observed that increasing the temperature has much greater effect on electrical conductivity enhancement than increasing the NDG nanosheet loading. Additionally, by considering the electrophoresis of the NDG nanosheets, a straightforward electrical conductivity model is established to modulate and understand the experimental results

  5. Hysteresis in the relation between moisture uptake and electrical conductivity in neat epoxy

    KAUST Repository

    Lubineau, Gilles

    2017-05-11

    Monitoring changes in electrical conductivity is a simple way to assess the water uptake from environmental moisture in polymers. However, the relation between water uptake and changes in conductivity is not fully understood. We monitored changes in the electrical volume conductivity of an anhydride-cured epoxy polymer during moisture sorption-desorption experiments. Gravimetric analysis showed that the polymer exhibits a two-stage sorption behavior resulting from the competition between diffusive and reactive mechanisms. As expected, the macroscopic electrical conductivity increases with the diffusion of water. However, our most surprising observation was severe hysteresis in the relation between water uptake and electrical conductivity during the sorption and desorption experiments. This indicates that change in the electrical conductivity depends on both the water uptake and the competition between the diffusive and reactive mechanisms. We studied samples with various thicknesses to determine the relative effects of the diffusive and reactive mechanisms. This is an important observation as it means that general electrical monitoring techniques should be used cautiously when it comes to measuring the moisture content of polymer or polymer-based composite samples.

  6. Sensing the water content of honey from temperature-dependent electrical conductivity

    International Nuclear Information System (INIS)

    Guo, Wenchuan; Liu, Yi; Zhu, Xinhua; Zhuang, Hong

    2011-01-01

    In order to predict the water content in honey, electrical conductivity was measured on blossom honey types milk-vetch, jujube and yellow-locust with the water content of 18–37% between 5 and 40 °C. The regression models of electrical conductivity were developed as functions of water content and temperature. The results showed that increases in either water content or temperature resulted in an increase in the electrical conductivity of honey with greater changes at higher water content and/or higher temperature. The linear terms of water content and temperature, a quadratic term of water content, and the interaction effect of water content and temperature had significant influence on the electrical conductivity of honey (p < 0.0001). Regardless of blossom honey type, the linear coefficient of the determination of measured and calculated electrical conductivities was 0.998 and the range error ratio was larger than 100. These results suggest that the electrical conductivity of honey might be used to develop a detector for rapidly predicting the water content in blossom honey

  7. Single flexible nanofiber to achieve simultaneous photoluminescence-electrical conductivity bifunctionality.

    Science.gov (United States)

    Sheng, Shujuan; Ma, Qianli; Dong, Xiangting; Lv, Nan; Wang, Jinxian; Yu, Wensheng; Liu, Guixia

    2015-02-01

    In order to develop new-type multifunctional composite nanofibers, Eu(BA)3 phen/PANI/PVP bifunctional composite nanofibers with simultaneous photoluminescence and electrical conductivity have been successfully fabricated via electrospinning technology. Polyvinyl pyrrolidone (PVP) is used as a matrix to construct composite nanofibers containing different amounts of Eu(BA)3 phen and polyaniline (PANI). X-Ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), fluorescence spectroscopy and a Hall effect measurement system are used to characterize the morphology and properties of the composite nanofibers. The results indicate that the bifunctional composite nanofibers simultaneously possess excellent photoluminescence and electrical conductivity. Fluorescence emission peaks of Eu(3+) ions are observed in the Eu(BA)3 phen/PANI/PVP photoluminescence-electrical conductivity bifunctional composite nanofibers. The electrical conductivity reaches up to the order of 10(-3)  S/cm. The luminescent intensity and electrical conductivity of the composite nanofibers can be tuned by adjusting the amounts of Eu(BA)3 phen and PANI. The obtained photoluminescence-electrical conductivity bifunctional composite nanofibers are expected to possess many potential applications in areas such as microwave absorption, molecular electronics, biomedicine and future nanomechanics. More importantly, the design concept and construction technique are of universal significance to fabricate other bifunctional one-dimensional naonomaterials. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Optimal duration of ultra low frequency-transcutaneous electrical nerve stimulation (ULF-TENS) therapy for muscular relaxation in neuromuscular occlusion: A preliminary clinical study.

    Science.gov (United States)

    Esclassan, Rémi; Rumerio, Anaïs; Monsarrat, Paul; Combadazou, Jean Claude; Champion, Jean; Destruhaut, Florent; Ghrenassia, Christophe

    2017-05-01

    The primary aim of this work was to determine the duration of ultra-low-frequency transcutaneous electrical nerve stimulation (ULF-TENS) application necessary to achieve sufficient relaxation of the masticatory muscles. A secondary aim was to analyze the influence of stimulation on muscle relaxation in pathological subjects and determine whether ULF-TENS has a noteworthy impact on muscle relaxation. Sixteen adult subjects with temporomandibular disorders (TMD) and muscle pain and a group of four control subjects were included in this study. ULF-TENS was applied, and muscular activities of the masseter, temporal, and sternocleidomastoid muscles (SCM) were recorded for 60 min. Significant relaxation was achieved in the TMD group from 20, 40, and 60 min for the temporal, masseter, and SCM muscles (p TENS application would last 40 min to obtain sufficient muscle relaxation both in patients with masticatory system disorders and healthy subjects, a time constraint that is consistent with everyday clinical practice.

  9. Analysis of the electrical conduction in CdHgTe crystals

    International Nuclear Information System (INIS)

    Dziuba, Z.

    1987-01-01

    The electrical conduction versus magnetic field in p-like CdHgTe samples at 77 K is investigated by analysing the conductivity tensor components. The electrical conduction is mainly due to electrons in the conduction band and low-mobility carriers in an impurity band. In the investigated samples Cd/sub x/Hg/sub 1-x/Te with the composition x approximately 0.17 the concentration of electrons in the conduction band is higher than the intrinsic one and in samples with the composition close to HgTe the concentration of electrons in the conduction band is equal to or lower than the intrinsic one. The model of a half-filled impurity band situated close to the bottom of the conduction band is proposed to account for the concentration of electrons in the conduction band. (author)

  10. Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges.

    Science.gov (United States)

    Manthilake, Geeth; Bolfan-Casanova, Nathalie; Novella, Davide; Mookherjee, Mainak; Andrault, Denis

    2016-05-01

    Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10(-3) S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10(-1) S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.

  11. Lightweight magnesium nanocomposites: electrical conductivity of liquid magnesium doped by CoPd nanoparticles

    Science.gov (United States)

    Yakymovych, Andriy; Slabon, Adam; Plevachuk, Yuriy; Sklyarchuk, Vasyl; Sokoliuk, Bohdan

    2018-04-01

    The effect of monodisperse bimetallic CoPd NP admixtures on the electrical conductivity of liquid magnesium was studied. Temperature dependence of the electrical conductivity of liquid Mg98(CoPd)2, Mg96(CoPd)4, and Mg92(CoPd)8 alloys was measured in a wide temperature range above the melting point by a four-point method. It was shown that the addition of even small amount of CoPd nanoparticles to liquid Mg has a significant effect on the electrical properties of the melts obtained.

  12. High-performance electrically conductive silver paste prepared by silver-containing precursor

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jianguo; Cao, Yu; Li, Xiangyou; Wang, Xiaoye; Zeng, Xiaoyan [Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Wuhan (China)

    2010-09-15

    A high-performance electrically conductive silver paste with no solid particles before drying and/or sintering is developed, in which silver-containing precursor is employed as conductive functional phase. Thermogravimetry analysis, volume electrical resistivity tests and sintering experiments show that the paste with about 14 wt.% silver pristine content is able to achieve the volume electrical resistivity of (2-3) x 10{sup -5} {omega} cm after it is sintered at 220 C. A micro-pen direct-writing process indicates that it is very suitable for the fabrication of high-resolution (25 {mu}m) and high-integration devices and apparatus. (orig.)

  13. Investigation of electric conductivity, viscosity and density of LiBF/sub 4/-1,3-dioxolane system in homogeneity region

    Energy Technology Data Exchange (ETDEWEB)

    Plakhotnik, V N; Tovmash, N F; Mishustin, A N; Dam' e, V N

    1987-01-01

    Solutions of lithium tetrafluoborate in 1,3-dioxolane (DOL) in temperature range and concentrations limiting the homogeneity region from the side of salt crystallization and formation of polymer structures from -30 deg to +25 deg and from 10/sup -6/ to 1.4 mol/l. are investigated using methods of conductometry, densimetry, viscosimetry and by measuring time of spinlattice /sup 7/Li nuclei relaxation. The dissociation constant of LiBF/sub 4/ in DOL (pK/sub D/=4.9+-0.2 at 25 deg) is determined. Comparison with systems based on 1,2-dimethoxyethane and tetrahydrofurane studied earlier is carried out. Suppositions concerning considerable contribution of ion molecular structures with participation of salt ions and solvent molecules to electric conductivity are stated, and it agrees with the data on measurements of velocities of spin-lattice relaxation of /sup 7/Li nuclei.

  14. Energy-Saving Sintering of Electrically Conductive Powders by Modified Pulsed Electric Current Heating Using an Electrically Nonconductive Die

    Science.gov (United States)

    Ito, Mikio; Kawahara, Kenta; Araki, Keita

    2014-04-01

    Sintering of Cu and thermoelectric Ca3Co4O9 was tried using a modified pulsed electric current sintering (PECS) process, where an electrically nonconductive die was used instead of a conventional graphite die. The pulsed electric current flowed through graphite punches and sample powder, which caused the Joule heating of the powder compact itself, resulting in sintering under smaller power consumption. Especially for the Ca3Co4O9 powder, densification during sintering was also accelerated by this modified PECS process.

  15. Fluorine follows water: Effect on electrical conductivity of silicate minerals by experimental constraints from phlogopite

    Science.gov (United States)

    Li, Yan; Jiang, Haotian; Yang, Xiaozhi

    2017-11-01

    Fluorine and hydroxyl groups are minor constituents of silicate minerals, and share a lot of similarities concerning their physical and chemical properties. Hydroxyl groups significantly enhance the electrical conductivity of many silicate minerals, and it is expected that fluorine would have a comparable effect. This, however, has never been documented quantitatively. Here we present experimental approaches on this issue, by investigating the electrical conductivity of phlogopite with a wide range of fluorine content (but with broadly similar contents for other major elements). Electrical conductivities of gem-quality single crystal phlogopites, with samples prepared along the same orientation (normal to the (0 0 1) plane), were determined at 1 GPa and 200-650 °C using an end-loaded piston cylinder apparatus and a Solartron-1260 Impedance/Gain Phase Analyzer over the frequency range of 106 to 0.1 Hz. The complex spectra usually show an arc in the high frequency range and a short tail in the low frequency range, which are caused by lattice conduction and electrode effects, respectively. The electrical conductivity increases with increasing fluorine content, and the main charge carriers are fluorine. The activation enthalpies are ∼180 to 200 kJ/mol, nearly independent of fluorine content. The conductivity is linearly proportional to the content of fluorine, with an exponent factor of ∼1. The results demonstrate that conduction by fluorine leads to very high electrical conductivity at high temperatures. The influence of fluorine on electrical conductivity may be compared to that of hydrogen in nominally anhydrous minerals. This, along with the close association of fluorine and hydroxyl groups in silicate minerals and their similar crystal-chemical behaviors, suggests a more general role of fluorine in enhancing the electrical conductivity of many silicate minerals. Fluorine-rich assemblages, e.g., phlogopite and amphibole, could be locally enriched in the upper

  16. Electrical Impedance Spectroscopy for Electro-Mechanical Characterization of Conductive Fabrics

    Directory of Open Access Journals (Sweden)

    Tushar Kanti Bera

    2014-06-01

    Full Text Available When we use a conductive fabric as a pressure sensor, it is necessary to quantitatively understand its electromechanical property related with the applied pressure. We investigated electromechanical properties of three different conductive fabrics using the electrical impedance spectroscopy (EIS. We found that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures. When we apply a mechanical tension or compression, there occur structural deformations in the conductive fabrics altering their apparent electrical impedance spectra. For a stretchable conductive fabric, the impedance magnitude increased or decreased under tension or compression, respectively. For an almost non-stretchable conductive fabric, both tension and compression resulted in decreased impedance values since the applied tension failed to elongate the fabric. To measure both tension and compression separately, it is desirable to use a stretchable conductive fabric. For any conductive fabric chosen as a pressure-sensing material, its resistivity under no loading conditions must be carefully chosen since it determines a measurable range of the impedance values subject to different amounts of loadings. We suggest the EIS method to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor.

  17. Carbon nanotubes with silver nanoparticle decoration and conductive polymer coating for improving the electrical conductivity of polycarbonate composites

    KAUST Repository

    Patole, Archana S.

    2015-01-01

    We proposed a strategy to enhance the conductivity of polycarbonate by using three-phase hybrid metallic/non-metallic fillers. Ethylene diamine (EDA) functionalized multiwalled carbon nanotubes (MWCNT-EDA) are first decorated with silver nanoparticles. These Ag/ MWCNT-EDA fillers are then coated with a conductive layer of ethylene glycol treated PEDOT: PSS (poly [3,4-ethylenedioxythiophene]: poly [styrenesulfonate]) (EP). In such an approach, the MWCNT backbone is covered by a highly conductive coating made of Ag nanoparticles surrounded by EP. To understand how Ag and EP form a highly conductive coating, the effect of different wt% of Ag nanoparticles on EP was studied. Ag nanoparticles around the size of 128 ± 28 nmeffectively lowered the volume resistivity of bulk EP, resulting in a highly conducting Ag/EP blend. We found that in the final Ag/MWCNT-EDA/EP assembly, the EP coating enhances the electrical conductivity in two ways: (1) it is an efficient dispersing agent that helps in achieving a uniform dispersion of the Ag/MWCNT-EDA and (2) it acts as a conductive bridge between particles (Ag and MWCNT-EDA), reducing the particle to particle resistivity. When inserted into polycarbonate, this three-phase blend successfully reduced the volume resistivity of the polymer by two orders of magnitude compared with previous approaches.

  18. Study on a Haptic Sensor Using MCF (Magnetic Compound Fluid) Electric Conductive Rubber

    Science.gov (United States)

    Zheng, Yaoyang; Shimada, Kunio

    To provide a new composite material having a high degree of sensitivity regarding both electrical conduction and temperature for the field of robotics or sensing, we have developed magnetic rubber that contains a network-like magnetic cluster. We compared the temperature response of MCF rubber with others rubbers made under various experimental conditions, allowing us to find an optimum condition for making MCF rubber. The temperature response was obtained by an experimental equation. We also compared the electric conductivity of MCF rubber with that of ordinary electric conductive rubber and found that its electric sensitivity was lower at a small deformation, but increased at larger deformations. Therefore, MCF rubber has proven itself effective as a switching sensor when a small deformation is applied.

  19. Effective electrical conductivity of carbon nanotube-polymer composites: a simplified model and its validation

    International Nuclear Information System (INIS)

    Jang, Sung-Hwan; Yin, Huiming

    2015-01-01

    A simplified model is presented to predict the effective electrical conductivity of carbon nanotube(CNT)-polymer composite with different material proportions, which is validated by the experiments of multi-walled CNT/polydimethylsiloxane (PDMS) composites. CNTs are well dispersed in a PDMS matrix, and the mixture is then cured and cast into thin films for electrical characterization. The CNTs are assumed to be statistically uniformly distributed in the PDMS matrix with the three-dimensional (3D) waviness. As the proportion of CNTs increases to a certain level, namely the percolation threshold, the discrete CNTs start to connect with each other, forming a 3D network which exhibits a significant increase of effective electrical conductivity. The eight-chain model has been used to predict the effective electrical conductivity of the composite, in which the contact resistance between CNTs has been considered through the Simmons’ equation. The eight-chain network features can be significantly changed with the modification to mixing process, CNT length and diameter, and CNT clustering and curling. A Gaussian statistics-based formulation is used to calculate the effective length of a single CNT well dispersed in the matrix. The modeling results of effective electrical conductivity agree with the experiments very well, which are highly dependent on a contact resistance between CNTs and the waviness of the CNTs. The effect of inner-nanotube distance and diameter of CNTs on the effective electrical conductivity of the CNT/PDMS composite is also discussed. (paper)

  20. Heterogeneous in situ polymerization of polyaniline (PANI) nanofibers on cotton textiles: Improved electrical conductivity, electrical switching, and tuning properties.

    Science.gov (United States)

    Tissera, Nadeeka D; Wijesena, Ruchira N; Rathnayake, Samantha; de Silva, Rohini M; de Silva, K M Nalin

    2018-04-15

    Electrically conductive cotton fabric was fabricated by in situ one pot oxidative polymerization of aniline. Using a simple heterogeneous polymerization method, polyaniline (PANI) nano fibers with an average fiber diameter of 40-75 nm were grafted in situ onto cotton fabric. The electrical conductivity of the PANI nanofiber grafted fabric was improved 10 fold compared to fabric grafted with PANI nanoclusters having an average cluster size of 145-315 nm. The surface morphology of the cotton fibers was characterized using SEM and AFM. Electrical conductivity of PANI nanofibers on the cotton textile was further improved from 76 kΏ/cm to 1 kΏ/cm by increasing the HCl concentration from 1 M to 3 M in the polymerization medium. PANI grafted cotton fabrics were analyzed using FTIR, and the data showed the presence of polyaniline functional groups on the treated fabric. Further evidence was present for the chemical interaction of PANI with cellulose. Dopant level and morphology dependent electron transition behavior of PANI nanostructures grafted on cotton fabric was further characterized using UV-vis spectroscopy. The electrical conductivity of the PANI nano fiber grafted cotton fabric can be tuned by immersing the fabric in pH 2 and pH 6 solutions for multiple cycles. Copyright © 2018. Published by Elsevier Ltd.

  1. Change in the electrical conductivity of SnO2 crystal from n-type to p-type conductivity

    International Nuclear Information System (INIS)

    Villamagua, Luis; Stashans, Arvids; Lee, Po-Ming; Liu, Yen-Shuo; Liu, Cheng-Yi; Carini, Manuela

    2015-01-01

    Highlights: • Switch from n-type to p-type conductivity in SnO 2 has been studied. • Computational DFT + U method where used. • X-ray diffraction and X-ray photoelectron spectroscopy where used. • Al- and N-codoped SnO 2 compound shows stable p-type conductivity. • Low resistivity (3.657 × 10 −1 Ω cm) has been obtained. • High carrier concentration (4.858 × 10 19 cm −3 ) has been obtained. - Abstract: The long-sought fully transparent technology will not come true if the n region of the p–n junction does not get as well developed as its p counterpart. Both experimental and theoretical efforts have to be used to study and discover phenomena occurring at the microscopic level in SnO 2 systems. In the present paper, using the DFT + U approach as a main tool and the Vienna ab initio Simulation Package (VASP) we reproduce both intrinsic n-type as well as p-type conductivity in concordance to results observed in real samples of SnO 2 material. Initially, an oxygen vacancy (1.56 mol% concentration) combined with a tin-interstitial (1.56 mol% concentration) scheme was used to achieve the n-type electrical conductivity. Later, to attain the p-type conductivity, crystal already possessing n-type conductivity, was codoped with nitrogen (1.56 mol% concentration) and aluminium (12.48 mol% concentration) impurities. Detailed explanation of structural changes endured by the geometry of the crystal as well as the changes in its electrical properties has been obtained. Our experimental data to a very good extent matches with the results found in the DFT + U modelling

  2. Pressure dependence of thermal conductivity and specific heat in CeRh2Si2 measured by an extended thermal relaxation method

    Science.gov (United States)

    Nishigori, Shijo; Seida, Osamu

    2018-05-01

    We have developed a new technique for measuring thermal conductivity and specific heat under pressure by improving a thermal relaxation method. In this technique, a cylindrical sample with a small disc heater is embedded in the pressure-transmitting medium, then temperature variations of the sample and heater were directly measured by thermocouples during a heating and cooling process. Thermal conductivity and specific heat are estimated by comparing the experimental data with temperature variations simulated by a finite element method. The obtained thermal conductivity and specific heat of the test sample CeRh2Si2 exhibit a small enhancement and a clear peak arising from antiferromagnetic transition, respectively. The observation of these typical behaviors for magnetic compounds indicate that the technique is valid for the study on thermal properties under pressure.

  3. Density, dynamic viscosity, and electrical conductivity of pyridinium-based hydrophobic ionic liquids

    International Nuclear Information System (INIS)

    Liu, Qing-Shan; Li, Pei-Pei; Welz-Biermann, Urs; Chen, Jian; Liu, Xiao-Xia

    2013-01-01

    Highlights: • Targets of this research are hydrophobic series ionic liquids. • Density, dynamic viscosity and electrical conductivity were determined. • Influences of methylene to properties were discussed. • Influences of methyl group on pyridinium ring position to properties were discussed. • Relationship of ρ, η and σ were described systematically. -- Abstract: Air and water stable hydrophobic ionic liquids (ILs) were synthesized: N-propyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide [C 3 3mpy][NTf 2 ], N-hexyl-3-methylpyridinium bis(trifluoromethylsulfonyl)imide [C 6 3mpy][NTf 2 ], and N-hexyl-4-methylpyridinium bis(trifluoromethylsulfonyl)imide [C 6 4mpy][NTf 2 ]. Density, dynamic viscosity, and electrical conductivity of ILs were determined at atmospheric pressure in the temperature range of (278 to 353) K. The effects of methylene and methyl groups to density, dynamic viscosity, and electrical conductivity, respectively, were discussed. The thermal expansion coefficient, molecular volume, standard molar entropy, and lattice energy of the samples were estimated in terms of empirical and semi-empirical equations based on the density values. The temperature dependence on dynamic viscosity and electrical conductivity values of the ILs were discussed by Vogel–Fulcher–Tamman (VFT) and Arrhenius equations. The molar conductivities were calculated by density and electrical conductivity values

  4. Using Rouse-Fowler model to describe radiation-induced electrical conductivity of nanocomposite materials

    Science.gov (United States)

    Dyuryagina, N. S.; Yalovets, A. P.

    2017-05-01

    Using the Rouse-Fowler (RF) model this work studies the radiation-induced electrical conductivity of a polymer nanocomposite material with spherical nanoparticles against the intensity and exposure time of gamma-ray, concentration and size of nanoparticles. The research has found the energy distribution of localized statesinduced by nanoparticles. The studies were conducted on polymethylmethacrylate (PMMA) with CdS nanoparticles.

  5. Pyroelectric properties and electrical conductivity in samarium doped BiFeO 3 ceramics

    KAUST Repository

    Yao, Yingbang; Liu, Wenchao; Mak, C. L.

    2012-01-01

    . This electrical conduction was attributed to oxygen vacancy existing in the samples. An activation energy of ∼0.7 eV for the conduction process was found to be irrespective of the Sm 3+ doping level. On the other hand, the magnetic Néel temperature (T N) decreased

  6. Pressure effect on the electrical conductivity and superconductivity of beta-(BDA-TTP)2I3.

    Science.gov (United States)

    Yamada, Jun-Ichi; Fujimoto, Kazuya; Akutsu, Hiroki; Nakatsuji, Shin'ichi; Miyazaki, Akira; Aimatsu, Masashi; Kudo, Satoshi; Enoki, Toshiaki; Kikuchi, Koichi

    2006-03-28

    The pressure-induced electrical conductivity properties of beta-(BDA-TTP)2I3 have been investigated; the salt exhibits a dramatic change in the conductivity behaviour above ca. 10 kbar and undergoes a superconducting transition with an onset near 10 K.

  7. The effect of ZnS thin film's electrical conductivity on electromagnetic ...

    African Journals Online (AJOL)

    The effect of electrical conductivity on an electromagnetic wave propagating through ZnS thin film is analyzed using electromagnetic wave equation with relevant boundary condition. The solution of this equation enabled us to obtain a parameter known as the skin depth that relates to the conductivity of the thin film. This was ...

  8. Thermoelectric power and electrical conductivity of strontium-doped lanthanum manganite

    DEFF Research Database (Denmark)

    Ahlgren, E.O.; Poulsen, F.W.

    1996-01-01

    Thermoelectric power and electrical conductivity of pure and 5, 10 and 20% strontium-doped lanthanum manganite are determined as function of temperature in air and of P-O2 at 1000 degrees C. At high temperatures the thermoelectric power is negative. Both thermoelectric power and conductivity...

  9. Water-dispersible small monodisperse electrically conducting antimony doped tin oxide nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Peters, K.; Zeller, P.; Štefanić, G.; Skoromets, Volodymyr; Němec, Hynek; Kužel, Petr; Fattakhova-Rohlfing, D.

    2015-01-01

    Roč. 27, č. 3 (2015), 1090-1099 ISSN 0897-4756 R&D Projects: GA ČR GA13-12386S Grant - others:AVČR(CZ) M100101218 Institutional support: RVO:68378271 Keywords : conducting nanoparticles * electrical conductivity * charge transport Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 9.407, year: 2015

  10. Characterization of electrical conductivity of carbon fiber reinforced plastic using surface potential distribution

    Science.gov (United States)

    Kikunaga, Kazuya; Terasaki, Nao

    2018-04-01

    A new method of evaluating electrical conductivity in a structural material such as carbon fiber reinforced plastic (CFRP) using surface potential is proposed. After the CFRP was charged by corona discharge, the surface potential distribution was measured by scanning a vibrating linear array sensor along the object surface with a high spatial resolution over a short duration. A correlation between the weave pattern of the CFRP and the surface potential distribution was observed. This result indicates that it is possible to evaluate the electrical conductivity of a material comprising conducting and insulating regions.

  11. Development of electrical insulation and conduction coating for fusion experimental devices

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Tsujimura, S. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Toyoda, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Inoue, M. [Mitsubishi Heavy Industries Ltd., Yokohama (Japan); Abe, T. [Japan Atomic Energy Research Inst., Naka (Japan); Murakami, Y. [Japan Atomic Energy Research Inst., Naka (Japan)

    1995-12-31

    Development of electrical insulation and conduction methods that can be applied for large components have been investigated for future large fusion experimental devices. A thermal spraying method is employed to coat the insulation or conduction materials on the structural components. Al{sub 2}O{sub 3} has been selected as an insulation material, while Cr{sub 3}C{sub 2}-NiCr and WC-NiCr have been chosen as conduction materials. These materials were coated on stainless steel base plates to examine the basic characteristics of the coated layers, such as their adhesive strength to the base plate and electrical resistance. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed sufficient frictional properties. The applicability of the spraying method was examined on a 100mm x 1000mm surface and found to be applicable for large surfaces in fusion experimental devices. (orig.).

  12. Development of electrical insulation and conduction coating for fusion experimental devices

    International Nuclear Information System (INIS)

    Onozuka, M.; Tsujimura, S.; Toyoda, M.; Inoue, M.; Abe, T.; Murakami, Y.

    1995-01-01

    Development of electrical insulation and conduction methods that can be applied for large components have been investigated for future large fusion experimental devices. A thermal spraying method is employed to coat the insulation or conduction materials on the structural components. Al 2 O 3 has been selected as an insulation material, while Cr 3 C 2 -NiCr and WC-NiCr have been chosen as conduction materials. These materials were coated on stainless steel base plates to examine the basic characteristics of the coated layers, such as their adhesive strength to the base plate and electrical resistance. It was found that they have sufficient electrical insulation and conduction properties, respectively. In addition, the sliding tests of the coated layers showed sufficient frictional properties. The applicability of the spraying method was examined on a 100mm x 1000mm surface and found to be applicable for large surfaces in fusion experimental devices. (orig.)

  13. Effects of transverse electric field and heterogeneity of a poorly electrically conducting fluid saturated nanoporous zeolites acquiring smart material properties

    International Nuclear Information System (INIS)

    Rudraiah, N.; Ranganna, G.; Shilpa, P.

    2013-01-01

    In this paper we explain a Mathematical Model involving Darcy linear drag, Forchheimer quadratic drag, horizontal density gradient and the variation of electrical conductivity due to organic substances dissolved in a heterogeneous Boussinesq poorly conducting couple stress fluid flow (PCPCSFF) through Nano Porous Zeolites regarded as densely packed porous media. Initially, the flow is at rest and set in motion due to initial piecewise horizontal concentration gradient. Analytical solutions, for electric potential using the Maxwell field equations and for velocity and density using nonlinear Darcy – Forchheimer equation in the presence of couple stress and electric force are obtained using the method of time series evolution. The analytical solutions for streamlines and density are computed for different values of time, t, for a particular value of electric number W 1 and couple stress parameter β and the results are depicted graphically in figures 1 and 2. From these figures we found that the streamlines are closer in the region of x 0 and the density profiles are concentrated in the lower region and develop curvature in the presence of electric field and couple stress parameter. The physical reason for the nature of streamlines and density profiles are given in the last section and some important conclusions are drawn. (author)

  14. Towards Practical Application of Paper based Printed Circuits: Capillarity Effectively Enhances Conductivity of the Thermoplastic Electrically Conductive Adhesives

    Science.gov (United States)

    Wu, Haoyi; Chiang, Sum Wai; Lin, Wei; Yang, Cheng; Li, Zhuo; Liu, Jingping; Cui, Xiaoya; Kang, Feiyu; Wong, Ching Ping

    2014-09-01

    Direct printing nanoparticle-based conductive inks onto paper substrates has encountered difficulties e.g. the nanoparticles are prone to penetrate into the pores of the paper and become partially segmented, and the necessary low-temperature-sintering process is harmful to the dimension-stability of paper. Here we prototyped the paper-based circuit substrate in combination with printed thermoplastic electrically conductive adhesives (ECA), which takes the advantage of the capillarity of paper and thus both the conductivity and mechanical robustness of the printed circuitsweredrastically improved without sintering process. For instance, the electrical resistivity of the ECA specimen on a pulp paper (6 × 10-5Ω.cm, with 50 wt% loading of Ag) was only 14% of that on PET film than that on PET film. This improvement has been found directly related to the sizing degree of paper, in agreement with the effective medium approximation simulation results in this work. The thermoplastic nature also enables excellent mechanical strength of the printed ECA to resist repeated folding. Considering the generality of the process and the wide acceptance of ECA technique in the modern electronic packages, this method may find vast applications in e.g. circuit boards, capacitive touch pads, and radio frequency identification antennas, which have been prototyped in the manuscript.

  15. Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

    Directory of Open Access Journals (Sweden)

    L. Dai

    2018-03-01

    Full Text Available The electrical conductivity of gneiss samples with different chemical compositions (WA = Na2O + K2O + CaO  =  7.12, 7.27 and 7.64 % weight percent was measured using a complex impedance spectroscopic technique at 623–1073 K and 1.5 GPa and a frequency range of 10−1 to 106 Hz. Simultaneously, a pressure effect on the electrical conductivity was also determined for the WA = 7.12 % gneiss. The results indicated that the gneiss conductivities markedly increase with total alkali and calcium ion content. The sample conductivity and temperature conform to an Arrhenius relationship within a certain temperature range. The influence of pressure on gneiss conductivity is weaker than temperature, although conductivity still increases with pressure. According to various ranges of activation enthalpy (0.35–0.52 and 0.76–0.87 eV at 1.5 GPa, two main conduction mechanisms are suggested that dominate the electrical conductivity of gneiss: impurity conduction in the lower-temperature region and ionic conduction (charge carriers are K+, Na+ and Ca2+ in the higher-temperature region. The electrical conductivity of gneiss with various chemical compositions cannot be used to interpret the high conductivity anomalies in the Dabie–Sulu ultrahigh-pressure metamorphic belt. However, the conductivity–depth profiles for gneiss may provide an important constraint on the interpretation of field magnetotelluric conductivity results in the regional metamorphic belt.

  16. Relative contribution of ionospheric conductivity and electric field to the auroral electrojets

    International Nuclear Information System (INIS)

    Kamide, Y.; Vickrey, J.F.

    1983-01-01

    Data from continuous scans of the Chatanika radar beam along the magnetic meridian plane are used to the determine the latitudinal profile of height-integrated ionospheric conductivities and horizontal electric fields, from which the latitudinal distribution of ionospheric currents is deduced. The observations cover invariant latitudes between 62 0 and 68 0 , where the IMS Alaska meridian chain of magnetometers was also in operation. Although the conductivities and the electric fields are interrelated, the relative importance of the two in driving the eastward and westward auroral electrojet currents can be assessed. It is found that for moderate and large current densities (i.e., > or approx. =0.2 A/m), the northward electric field strength increases as the magnitude of the eastward electrojet in the evening sector increases. The height-integrated Hall conductivity stays generally at the level of 10 mhos even when the current density becomes as large as 1 A/m. However, when the eastward electrojet is small, substantial electric fields of 10-20 mV/m may still exist as if the magnetosphere has a persistent voltage source. There appear to be two distinct components to the westward electrojet. In the midnight and early morning sestors (>0300 MLT) intensity is characterized by a weak southward electric field and a high Hall conductivity, whereas its late morning portion (>0300 MLT) is dominated by a strong southward electric field

  17. Studies on polymer electrolyte poly(vinyl) pyrrolidone (PVP) complexed with ionic liquid: Effect of complexation on thermal stability, conductivity and relaxation behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Saroj, A.L. [Department of Physics, Banaras Hindu University, Varanasi, 221005 (India); Singh, R.K., E-mail: rksingh_17@rediffmail.com [Department of Physics, Banaras Hindu University, Varanasi, 221005 (India); Chandra, S. [Department of Physics, Banaras Hindu University, Varanasi, 221005 (India)

    2013-03-01

    Highlights: Black-Right-Pointing-Pointer PVP + IL based polymer electrolyte films have been prepared and studied. Black-Right-Pointing-Pointer The complexation/interaction of PVP with IL has been confirmed by FT-IR analysis. Black-Right-Pointing-Pointer The conductivity and relaxation frequency increases with increasing IL content. Black-Right-Pointing-Pointer Two relaxation peaks for complexed and uncomplexed PVP with IL have been observed. - Abstract: Polymer electrolyte films of PVP + x wt% ionic liquid (IL) (1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF{sub 4}]) for x = 0, 5, 10, 15, 20, 25 wt% have been prepared using solution cast technique. These films were characterized by TGA, DSC, FT-IR and ac impedance spectroscopy techniques. From XRD studies it is found that the inclusion of IL increases the amorphocity of polymeric membranes. DSC thermograms show that the glass transition (T{sub g}) and melting temperatures (T{sub m}) of PVP shift upon complexation with IL. FT-IR analysis shows the complexation of PVP with IL. Thermogravimetric studies show that PVP decomposes in a single step while PVP/IL membranes exhibit two step decomposition; lower value of decomposition temperature corresponds to the decomposition of PVP/IL complex while the higher decomposition temperature has been attributed to the decomposition of PVP. The decomposition temperature of PVP/IL complex decreases with the increasing amount of IL in the PVP membrane. Temperature dependence of conductivity and dielectric relaxation frequencies have also been studied for PVP and PVP/IL membranes. Both show thermally activated Arrhenius behaviour.

  18. Conductivity peak, relaxation dynamics, and superconducting gap of YBa2Cu3O7 studied by terahertz and femtosecond optical spectroscopies

    International Nuclear Information System (INIS)

    Frenkel, A.; Gao, F.; Liu, Y.; Whitaker, J.F.; Uher, C.; Hou, S.Y.; Phillips, J.M.

    1996-01-01

    Recent measurements at microwave, terahertz (THz), and infrared frequencies have revealed a peak in σ 1 below T c . Based on our THz measurements, which were performed on high quality, single crystal films of YBCO (900 and 500 A), we have found that σ 1 features a peak which increases in amplitude and shifts to lower temperatures as frequency changes from 1.2 to 0.4 THz. Although the quasiparticle relaxation time extracted from these results using the two-fluid Drude model exhibits an enhancement below T c , the analysis may not be adequate to account for the strong frequency dependence of the conductivity peak by the competition between the drop in scattering rate and the decreasing normal fluid density with temperature. On the contrary, we were able to account for the frequency dependent σ 1 by fitting with Mattis-Bardeen theory (modified to include scattering) using a slower average rate of increase of the anisotropic gap than for the BCS case as temperature decreases below T c . This is consistent with the higher normal fluid density (higher than Gorter-Casimir values) from the two-fluid model interpretation of our THz results. Thus, we have found evidence of BCS coherence factors in a high-T c superconductor with a slower than BCS gap increase below T c . We have discussed the role of coherence factors to account for the presence of the conductivity peak and the absence of the peak in NMR relaxation rate. Furthermore, we have presented a model for the quasiparticle relaxation time measured by the femtosecond pump-probe spectroscopy. This model allowed us to find a fit to the temperature-dependent energy gap function which is also consistent with the slower gap increase below T c

  19. Graphite nanoplatelets and carbon nanotubes based polyethylene composites: Electrical conductivity and morphology

    International Nuclear Information System (INIS)

    Haznedar, Galip; Cravanzola, Sara; Zanetti, Marco; Scarano, Domenica; Zecchina, Adriano; Cesano, Federico

    2013-01-01

    Graphite nanoplatelets (GNPs) and/or multiwalled-carbon nanotubes (MWCNTs)/low density polyethylene (LDPE) composites have been obtained either via melt-mixing or solvent assisted methods. Electrical properties of samples obtained through the above mentioned methods are compared and the conductance values as function of filler fraction are discussed. The corresponding percolation thresholds are evaluated. Conductivity maps images are acquired under low-potentials scanning electron microscopy (0.3 KV) and the relationship between the obtained conductivity images and electric properties is highlighted. The synergistic role of CNTs (1D) and GNPs (2D) in improving the conductive properties of the polymer composites has been shown. - Highlights: • Graphite nanoplatelets (GNPs) and GNPs/MWCNT LDPE composites. • Low potential SEM conductivity maps. • Conducting paths between 1D and 2D C-structures (synergistic effect) are obtained. • Composites based on hybrid 1D/2D combinations show lower percolation thresholds

  20. Strain-dependent magnetism and electrical conductivity of La1-xSrxCoO3

    International Nuclear Information System (INIS)

    Zeneli, Orkidia

    2011-01-01

    In this work, the effects of epitaxial strain and film thickness on the lattice structure, microstructure, magnetization and electrical conduction of La 1-x Sr x CoO 3 (LSCO) (x=0.18 and 0.30) thin films have been studied using thickness-dependent film series on several types of single-crystalline substrates. Alternatively, the direct effect of strain has been probed using a piezoelectric substrate. La 0.7 Sr 0.3 CoO 3 is a ferromagnetic metal, whereas La 0.82 Sr 0.18 CoO 3 is at the phase boundary between the ferromagnetic metal and an insulating spin glass phase. Epitaxial biaxial strain in La 1-x Sr x CoO 3 (x=0.18-0.3) films is known to reduce the ferromagnetic double exchange interactions. It has further been suggested for the control of the crystal field splitting of the Co ions which may be utilized to manipulate the spin state. The LSCO (x = 0.18 and 0.30) films have been grown by pulsed laser deposition (PLD) on substrates of LaAlO 3 , SrTiO 3 , (PbMg 1/3 Nb 2/3 O 3 ) 0.72 (PbTiO 3 ) 0.28 (PMN-PT) and (LaAlO 3 ) 0.3 (Sr 2 TaAlO 6 ) 0.7 (LSAT), which provide different strain states and, in the case of PMN-PT, a reversibly controllable strain. Thickness-dependent series of La 0.82 Sr 0.18 CoO 3 on SrTiO 3 and LaAlO 3 as well as of La 0.7 Sr 0.3 CoO 3 on LSAT have been studied. The lattice parameters of the epitaxially grown films were determined from X-ray diffraction measurements (Bragg-Brentano method and reciprocal space mapping). Large tensile strains of 2% can be achieved in thicker films of up to 100 nm. On the other hand, the films under larger tensile strain have cracks and reveal ordered superstructures in HRTEM images which are tentatively attributed to ordered oxygen vacancies. The Curie temperature and the magnetic moment of the x=0.18 films increases towards larger film thickness in qualitative agreement with the joined effects of strain relaxation and finite thickness on magnetic ordering. In order to separate the direct strain effect from the

  1. Frequency and voltage dependence dielectric properties, ac electrical conductivity and electric modulus profiles in Al/Co{sub 3}O{sub 4}-PVA/p-Si structures

    Energy Technology Data Exchange (ETDEWEB)

    Bilkan, Çiğdem, E-mail: cigdembilkan@gmail.com [Department of Physics, Faculty of Sciences, The University of Çankırı Karatekin, 18100 Çankırı (Turkey); Azizian-Kalandaragh, Yashar [Department of Physics, Faculty of Science, The University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Altındal, Şemsettin [Department of Physics, Faculty of Sciences, The University of Gazi, 06500 Ankara (Turkey); Shokrani-Havigh, Roya [Department of Physics, Faculty of Science, The University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2016-11-01

    In this research a simple microwave-assisted method have been used for preparation of cobalt oxide nanostructures. The as-prepared sample has been investigated by UV–vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM). On the other hand, frequency and voltage dependence of both the real and imaginary parts of dielectric constants (ε′, ε″) and electric modulus (M′ and M″), loss tangent (tanδ), and ac electrical conductivity (σ{sub ac}) values of Al/Co{sub 3}O{sub 4}-PVA/p-Si structures were obtained in the wide range of frequency and voltage using capacitance (C) and conductance (G/ω) data at room temperature. The values of ε′, ε″ and tanδ were found to decrease with increasing frequency almost for each applied bias voltage, but the changes in these parameters become more effective in the depletion region at low frequencies due to the charges at surface states and their relaxation time and polarization effect. While the value of σ is almost constant at low frequency, increases almost as exponentially at high frequency which are corresponding to σ{sub dc} and σ{sub ac}, respectively. The M′ and M″ have low values at low frequencies region and then an increase with frequency due to short-range mobility of charge carriers. While the value of M′ increase with increasing frequency, the value of M″ shows two peak and the peaks positions shifts to higher frequency with increasing applied voltage due to the decrease of the polarization and N{sub ss} effects with increasing frequency.

  2. Effect of the type of metal on the electrical conductivity and thermal properties of metal complexes: The relation between ionic radius of metal complexes and electrical conductivity

    Science.gov (United States)

    Morgan, Sh. M.; El-Ghamaz, N. A.; Diab, M. A.

    2018-05-01

    Co(II) complexes (1-4) and Ni(II) complexes (5-8) were prepared and characterized by elemental analysis, IR spectra and thermal analysis data. Thermal decomposition of all complexes was discussed using thermogravimetric analysis. The dielectric properties and alternating current conductivity were investigated in the frequency range 0.1-100 kHz and temperature range 300-660 K. The thermal activation energies of electrical conductivity (ΔE1 and ΔE2) values for complexes were calculated and discussed. The values of ΔE1 and ΔE2 for complexes (1-8) were found to decrease with increasing the frequency. Ac electrical conductivity (σac) values increases with increasing temperatures and the values of σac for Co(II) complexes are greater than Ni(II) complexes. Co(II) complexes showed a higher conductivity than other Ni(II) complexes due to the higher crystallinity as confirmed by X-ray diffraction analysis.

  3. Mathematical Modeling of Electrical Conductivity of Dielectric with Dispersed Metallic Inclusions

    Directory of Open Access Journals (Sweden)

    V. S. Zarubin

    2015-01-01

    Full Text Available Composites are increasingly used for application in engineering as structural, thermal protection and functional materials, including dielectrics, because of a wide variety of properties. The relative dielectric constant and the dielectric loss tangent are basic functional characteristics of a composite used as a dielectric. The quantitative level of these characteristics is mainly affected by the properties of the composite matrix and inclusions as well as their shape and volume concentration. Metallic inclusions in a dielectric, which serves as a function of the composite matrix, expand electrical properties of the composite in particular increase its dielectric constant and dielectric loss tangent and thereby greatly expand its application field. Dielectric losses are defined by the imaginary component of the complex value of the relative dielectric constant of the dielectric. At a relatively low vibration frequency of electromagnetic field affecting the dielectric, this value is proportional to the electrical conductivity of the dielectric and inversely proportional to the frequency. In order to predict the expected value of the electric conductivity of the dielectric with metallic inclusions, a mathematical model that properly describes the structure of the composite and the electrical interaction of the matrix and inclusions is required.In the paper, a mathematical model of the electrical interaction of the representative element of the composite structure and a homogeneous isotropic medium with electrical conductivity, which is desired characteristics of the composite, is constructed. Globular shape of the metallic inclusions as an average statistical form of dispersed inclusions with a comparable size in all directions is adopted. The inclusion is covered with a globular layer of electrical insulation to avoid percolation with increasing volume concentration of inclusions. Outer globular layer of representative structure of composite

  4. Influence of Electrical Conductivity, Days in Milk and Parity on Milk Production and Chemical Composition

    Directory of Open Access Journals (Sweden)

    Radu Ionel Neamț

    2016-10-01

    Full Text Available The aim of study was to assess milk production and chemical composition during the first 100 days of lactation, under the influence of electrical conductivity, parity and days in milk. Study was conducted at Research and Development Station for Bovine Arad, on 66 Romanian Spotted cows (20 primiparous, 46 multiparous. Significantly higher values (p≤0.017 of electrical conductivity were recorded for primiparous (10.15±0.09 mS/cm compared with multiparous (8.79±0.15 mS/cm. During the first 30 DIM electrical conductivity was higher (9.7±0.12 mS/cm than for 31 to 60 DIM (9.04±0.12 mS/cm; p≤0.001 and for 61 to 100 DIM (8.17±0.11 mS/cm, p≤0.001. Multifactorial regression model applied highlights significant influence of month of calving (p≤0.001 and DIM (p≤0.034 on the electrical conductivity, while parity had no influence (p>0.36. Medium and negative correlations were calculated between electrical conductivity and some chemical components (fat R=-0.15, protein R=-0.13, while to milk production correlation was positive (R=0.12. No significant correlations were obtained according to lactose content (R=-0.013. Dynamics of milk production and chemical composition have been significantly influenced by month of calving (p≤0.001, DIM (p≤0.001 and parity (p≤0.002. This study found no significant influence of milk electrical conductivity on milk production or chemical composition (p>0.59.

  5. Overvoltage effect on electrical discharge type in medium-conductivity water in inhomogeneous pulsed electric field

    Science.gov (United States)

    Panov, V. A.; Vasilyak, L. M.; Pecherkin, V. Ya; Vetchinin, S. P.; Son, E. E.

    2018-01-01

    The transition between thermal and streamer discharges has been observed experimentally in water solution with conductivity 100 μS/cm applying positive voltage pulses to pin-to-rod electrodes. The transition happens at five-fold pulse amplitude. Considering streamer propagation as an ionization wave helped to establish relation between the parameters governing transition from one to another discharge mechanism.

  6. Magnetoacoustic Imaging of Electrical Conductivity of Biological Tissues at a Spatial Resolution Better than 2 mm

    OpenAIRE

    Hu, Gang; He, Bin

    2011-01-01

    Magnetoacoustic tomography with magnetic induction (MAT-MI) is an emerging approach for noninvasively imaging electrical impedance properties of biological tissues. The MAT-MI imaging system measures ultrasound waves generated by the Lorentz force, having been induced by magnetic stimulation, which is related to the electrical conductivity distribution in tissue samples. MAT-MI promises to provide fine spatial resolution for biological tissue imaging as compared to ultrasound resolution. In t...

  7. Wireless Sensing System Using Open-circuit, Electrically-conductive Spiral-trace Sensor

    Science.gov (United States)

    Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

    2013-01-01

    A wireless sensing system includes a sensor made from an electrical conductor shaped to form an open-circuit, electrically-conductive spiral trace having inductance and capacitance. In the presence of a time-varying magnetic field, the sensor resonates to generate a harmonic response having a frequency, amplitude and bandwidth. A magnetic field response recorder wirelessly transmits the time-varying magnetic field to the sensor and wirelessly detects the sensor's response frequency, amplitude and bandwidth.

  8. Effect of silica concentration on electrical conductivity of epoxy resin-carbon black-silica nanocomposites

    International Nuclear Information System (INIS)

    Zhang Wei; Blackburn, Richard S.; Dehghani-Sanij, Abbas A.

    2007-01-01

    Electrical properties of nanocomposites are determined by the conductive paths of carbon black and influenced by a 'network' of silica. With increasing content of silica, carbon black (CB) particles are optimally dispersed, contributing to the generation of a conductive network between CB particles via direct particle contact and a tunneling effect; maximum conductivity for the epoxy resin-CB-silica nanocomposite described herein occurs at a ratio of 0.6:1.0 (SiO 2 :CB). As a non-conductive component, excessive silica will prevent electron flow, giving rise to low conductivity

  9. Electrical conduction in 7 nm wires constructed on λ-DNA

    International Nuclear Information System (INIS)

    Lund, John; Dong Jianchun; Deng Zhaoxiang; Mao Chengde; Parviz, Babak A

    2006-01-01

    We examine the morphological and electrical characteristics of nanowires fabricated on DNA templates via palladium (Pd) reduction. λ-DNA molecules were stretched and aligned on a mica surface using a molecular combing technique, followed by an electroless deposition of palladium, resulting in formation of nanowires with nominal width of 7 nm. We investigated the size distribution of nanowires with atomic force microscopy and made electrical connections to the wires by metal evaporation through multiple shadow masks. Electrical characterization of the nanowires under various bias conditions, variable temperature, and with different contact metal work functions revealed a conduction mechanism resembling that of granular metals

  10. Analysis of in-situ electrical conductivity data from the HFIR TRIST-ER1 experiment

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J.; Snead, L.L. [Oak Ridge National Lab., TN (United States); Shikama, T. [Tohoku Univ. (Japan)] [and others

    1997-08-01

    The current vs. applied voltage data generated from the HFIR TRIST-ER1 experiment have been analyzed to determine the electrical conductivity of the 15 aluminum oxide specimens and the MgO-insulated electrical cables as a function of irradiation dose. With the exception of the 0.05%Cr-doped sapphire (ruby) specimen, the electrical conductivity of the alumina specimens remained at the expected radiation induced conductivity (RIC) level of <10{sup -6} S/m during full-power reactor irradiation (10-16 kGy/s) at 450-500{degrees}C up to a maximum dose of {approximately}3 dpa. The ruby specimen showed a rapid initial increase in conductivity to {approximately}2 x 10{sup -4} S/m after {approximately}0.1 dpa, followed by a gradual decrease to <1 x 10{sup -6} S/m after 2 dpa. Nonohmic electrical behavior was observed in all of the specimens, and was attributed to preferential attraction of ionized electrons in the capsule gas to the unshielded low-side bare electrical leads emanating from the subcapsules. The electrical conductivity was determined from the slope of the specimen current vs. voltage curve at negative voltages, where the gas ionization effect was minimized. Dielectric breakdown tests performed on unirradiated mineral-insulated coaxial cables identical to those used in the high voltage coaxial cables during the 3-month irradiation is attributable to thermal dielectric breakdown in the glass seals at the end of the cables, as opposed to a radiation-induced electrical degradation (RIED) effect.

  11. Analysis of in-situ electrical conductivity data from the HFIR TRIST-ER1 experiment

    International Nuclear Information System (INIS)

    Zinkle, S.J.; Snead, L.L.; Shikama, T.

    1997-01-01

    The current vs. applied voltage data generated from the HFIR TRIST-ER1 experiment have been analyzed to determine the electrical conductivity of the 15 aluminum oxide specimens and the MgO-insulated electrical cables as a function of irradiation dose. With the exception of the 0.05%Cr-doped sapphire (ruby) specimen, the electrical conductivity of the alumina specimens remained at the expected radiation induced conductivity (RIC) level of -6 S/m during full-power reactor irradiation (10-16 kGy/s) at 450-500 degrees C up to a maximum dose of ∼3 dpa. The ruby specimen showed a rapid initial increase in conductivity to ∼2 x 10 -4 S/m after ∼0.1 dpa, followed by a gradual decrease to -6 S/m after 2 dpa. Nonohmic electrical behavior was observed in all of the specimens, and was attributed to preferential attraction of ionized electrons in the capsule gas to the unshielded low-side bare electrical leads emanating from the subcapsules. The electrical conductivity was determined from the slope of the specimen current vs. voltage curve at negative voltages, where the gas ionization effect was minimized. Dielectric breakdown tests performed on unirradiated mineral-insulated coaxial cables identical to those used in the high voltage coaxial cables during the 3-month irradiation is attributable to thermal dielectric breakdown in the glass seals at the end of the cables, as opposed to a radiation-induced electrical degradation (RIED) effect

  12. Reinforced carbon nanotubes as electrically conducting and flexible films for space applications.

    Science.gov (United States)

    Atar, Nurit; Grossman, Eitan; Gouzman, Irina; Bolker, Asaf; Hanein, Yael

    2014-11-26

    Chemical vapor deposition (CVD)-grown entangled carbon nanotube (CNT) sheets are characterized by high electrical conductivity and durability to bending and folding. However, since freestanding CNT sheets are mechanically weak, they cannot be used as stand-alone flexible films. In this work, polyimide (PI) infiltration into entangled cup-stacked CNT (CSCNT) sheets was studied to form electrically conducting, robust, and flexible films for space applications. The infiltration process preserved CNTs' advantageous properties (i.e., conductivity and flexibility), prevented CNT agglomeration, and enabled CNT patterning. In particular, the CNT-PI films exhibited ohmic electrical conductance in both the lateral and vertical directions, with a sheet resistivity as low as 122 Ω/□, similar to that of as-grown CNT sheets, with minimal effect of the insulating matrix. Moreover, this high conductivity was preserved under mechanical and thermal manipulations. These properties make the reported CNT-PI films excellent candidates for applications where flexibility, thermal stability, and electrical conductivity are required. Particularly, the developed CNT-PI films were found to be durable in space environment hazards such as high vacuum, thermal cycling, and ionizing radiation, and hence they are suggested as an alternative for the electrostatic discharge (ESD) protection layer in spacecraft thermal blankets.

  13. Magnetic resonance electrical impedance tomography (MREIT): conductivity and current density imaging

    International Nuclear Information System (INIS)

    Seo, Jin Keun; Kwon, Ohin; Woo, Eung Je

    2005-01-01

    This paper reviews the latest impedance imaging technique called Magnetic Resonance Electrical Impedance Tomography (MREIT) providing information on electrical conductivity and current density distributions inside an electrically conducting domain such as the human body. The motivation for this research is explained by discussing conductivity changes related with physiological and pathological events, electromagnetic source imaging and electromagnetic stimulations. We briefly summarize the related technique of Electrical Impedance Tomography (EIT) that deals with cross-sectional image reconstructions of conductivity distributions from boundary measurements of current-voltage data. Noting that EIT suffers from the ill-posed nature of the corresponding inverse problem, we introduce MREIT as a new conductivity imaging modality providing images with better spatial resolution and accuracy. MREIT utilizes internal information on the induced magnetic field in addition to the boundary current-voltage measurements to produce three-dimensional images of conductivity and current density distributions. Mathematical theory, algorithms, and experimental methods of current MREIT research are described. With numerous potential applications in mind, future research directions in MREIT are proposed

  14. Enhanced thermoelectric efficiency via orthogonal electrical and thermal conductances in phosphorene.

    Science.gov (United States)

    Fei, Ruixiang; Faghaninia, Alireza; Soklaski, Ryan; Yan, Jia-An; Lo, Cynthia; Yang, Li

    2014-11-12

    Thermoelectric devices that utilize the Seebeck effect convert heat flow into electrical energy and are highly desirable for the development of portable, solid state, passively powered electronic systems. The conversion efficiencies of such devices are quantified by the dimensionless thermoelectric figure of merit (ZT), which is proportional to the ratio of a device's electrical conductance to its thermal conductance. In this paper, a recently fabricated two-dimensional (2D) semiconductor called phosphorene (monolayer black phosphorus) is assessed for its thermoelectric capabilities. First-principles and model calculations reveal not only that phosphorene possesses a spatially anisotropic electrical conductance, but that its lattice thermal conductance exhibits a pronounced spatial-anisotropy as well. The prominent electrical and thermal conducting directions are orthogonal to one another, enhancing the ratio of these conductances. As a result, ZT may reach the criterion for commercial deployment along the armchair direction of phosphorene at T = 500 K and is close to 1 even at room temperature given moderate doping (∼2 × 10(16) m(-2) or 2 × 10(12) cm(-2)). Ultimately, phosphorene hopefully stands out as an environmentally sound thermoelectric material with unprecedented qualities. Intrinsically, it is a mechanically flexible material that converts heat energy with high efficiency at low temperatures (∼300 K), one whose performance does not require any sophisticated engineering techniques.

  15. Electrical conductivity improvement of strontium titanate doped lead vanadate glasses by nanocrystallization

    Energy Technology Data Exchange (ETDEWEB)

    El-Desoky, M.M., E-mail: mmdesoky@gmail.co [Physics Department, Faculty of Education, Suez Canal University, El-Arish (Egypt); Zayed, H.S.S.; Ibrahim, F.A.; Ragab, H.S. [Physics Department, Faculty of Education, Suez Canal University, El-Arish (Egypt)

    2009-11-15

    The structural and electrical conductivity (sigma) of annealed SrTiO{sub 3}-PbO{sub 2}-V{sub 2}O{sub 5} glasses were studied. The annealing of initially glass samples leads to formation of nanocrystalline grains embedded in the glassy matrix. XRD patterns of the glass-ceramic samples show that nanocrystals were embedded in the glassy matrix with an average grain size of 32 nm. The glass-ceramic nanocrystals obtained by annealing at temperatures close to the crystallization temperature T{sub c} exhibit enhancement of electrical conductivity up to four orders of magnitude than initially glasses. The enhancement of the electrical conductivity due to annealing was attributed to two interdependent factors: (i) an increase of concentration of V{sup 4+}-V{sup 5+} pairs; and (ii) formation of defective, well-conducting regions along the glass-crystallites interfaces. From the conductivity temperature relation, it was found that small polaron hopping model was applicable at temperature above theta{sub D}/2 (theta{sub D}, the Debye temperature). The electrical conduction at T >theta{sub D}/2 was due to non-adiabatic small polaron hopping (SPH) of electrons between vanadium ions. The parameters obtained from the fits of the experimental data to this model appear reasonable and are consistent with glass composition.

  16. Electrical conductivity improvement of strontium titanate doped lead vanadate glasses by nanocrystallization

    International Nuclear Information System (INIS)

    El-Desoky, M.M.; Zayed, H.S.S.; Ibrahim, F.A.; Ragab, H.S.

    2009-01-01

    The structural and electrical conductivity (σ) of annealed SrTiO 3 -PbO 2 -V 2 O 5 glasses were studied. The annealing of initially glass samples leads to formation of nanocrystalline grains embedded in the glassy matrix. XRD patterns of the glass-ceramic samples show that nanocrystals were embedded in the glassy matrix with an average grain size of 32 nm. The glass-ceramic nanocrystals obtained by annealing at temperatures close to the crystallization temperature T c exhibit enhancement of electrical conductivity up to four orders of magnitude than initially glasses. The enhancement of the electrical conductivity due to annealing was attributed to two interdependent factors: (i) an increase of concentration of V 4+ -V 5+ pairs; and (ii) formation of defective, well-conducting regions along the glass-crystallites interfaces. From the conductivity temperature relation, it was found that small polaron hopping model was applicable at temperature above θ D /2 (θ D , the Debye temperature). The electrical conduction at T >θ D /2 was due to non-adiabatic small polaron hopping (SPH) of electrons between vanadium ions. The parameters obtained from the fits of the experimental data to this model appear reasonable and are consistent with glass composition.

  17. Electrical conductivity measurement and thermogravimetric study of chromium-doped uranium dioxide

    International Nuclear Information System (INIS)

    Matsui, Tsuneo; Naito, Keiji

    1986-01-01

    The electrical conductivity and nonstoichiometric composition of (Usub(1-y)Crsub(y))Osub(2+x) (y=0.001 and 0.05) were measured in the range 1173 -17 2 ) -2 Pa by the four inserted wires method and thermogravimetry, respectively. The electrical conductivities of (Usub(1-y)Crsub(y))Osub(2+x) (y=0.01 and 0.05) were about one-order lower than that of UOsub(2+x), probably due to the presence of the chromium ion as an electron donor. The activation energies of (Usub(0.99)Crsub(0.01))Osub(2+x) and (Usub(0.95)Crsub(0.05))Osub(2+x) for the extrinsic conduction in the low oxygen partial pressure region were calculated to be 24.7+-1.3 and 25.9+-1.0 kJ.mol -1 , respectively from the Arrhenius plots of the electrical conductivities. These small values of the activation energy of (Usub(1-y)Crsub(y))Osub(2+x) may suggest the presence of the hopping mechanism for hole conduction, similarly to the case of UOsub(2+x). From the oxygen partial pressure dependences of both the electrical conductivity and the deviation x in (Usub(1-y)Crsub(y))Osub(2+x), the defect structure was discussed with the complex defect model consisting of oxygen vacancies and two kinds of interstitial oxygens. (orig.)

  18. Investigation on magnetoacoustic signal generation with magnetic induction and its application to electrical conductivity reconstruction

    International Nuclear Information System (INIS)

    Ma Qingyu; He Bin

    2007-01-01

    A theoretical study on the magnetoacoustic signal generation with magnetic induction and its applications to electrical conductivity reconstruction is conducted. An object with a concentric cylindrical geometry is located in a static magnetic field and a pulsed magnetic field. Driven by Lorentz force generated by the static magnetic field, the magnetically induced eddy current produces acoustic vibration and the propagated sound wave is received by a transducer around the object to reconstruct the corresponding electrical conductivity distribution of the object. A theory on the magnetoacoustic waveform generation for a circular symmetric model is provided as a forward problem. The explicit formulae and quantitative algorithm for the electrical conductivity reconstruction are then presented as an inverse problem. Computer simulations were conducted to test the proposed theory and assess the performance of the inverse algorithms for a multi-layer cylindrical model. The present simulation results confirm the validity of the proposed theory and suggest the feasibility of reconstructing electrical conductivity distribution based on the proposed theory on the magnetoacoustic signal generation with magnetic induction

  19. Electrical conductivity and ion diffusion in porcine meniscus: effects of strain, anisotropy, and tissue region.

    Science.gov (United States)

    Kleinhans, Kelsey L; McMahan, Jeffrey B; Jackson, Alicia R

    2016-09-06

    The purpose of the present study was to investigate the effects of mechanical strain, anisotropy, and tissue region on electrical conductivity and ion diffusivity in meniscus fibrocartilage. A one-dimensional, 4-wire conductivity experiment was employed to measure the electrical conductivity in porcine meniscus tissues from two tissue regions (horn and central), for two tissue orientations (axial and circumferential), and for three levels of compressive strain (0%, 10%, and 20%). Conductivity values were then used to estimate the relative ion diffusivity in meniscus. The water volume fraction of tissue specimens was determined using a buoyancy method. A total of 135 meniscus samples were measured; electrical conductivity values ranged from 2.47mS/cm to 4.84mS/cm, while relative ion diffusivity was in the range of 0.235 to 0.409. Results show that electrical conductivity and ion diffusion are significantly anisotropic (pmeniscus fibrocartilage, which is essential in developing new strategies to treat and/or prevent tissue degeneration. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. A Route for Polymer Nanocomposites with Engineered Electrical Conductivity and Percolation Threshold

    Directory of Open Access Journals (Sweden)

    Lawrence T. Drzal

    2010-02-01

    Full Text Available Polymer nanocomposites with engineered electrical properties can be made by tuning the fabrication method, processing conditions and filler’s geometric and physical properties. This work focuses on investigating the effect of filler’s geometry (aspect ratio and shape, intrinsic electrical conductivity, alignment and dispersion within the polymer, and polymer crystallinity, on the percolation threshold and electrical conductivity of polypropylene based nanocomposites. The conductive reinforcements used are exfoliated graphite nanoplatelets, carbon black, vapor grown carbon fibers and polyacrylonitrile carbon fibers. The composites are made using melt mixing followed by injection molding. A coating method is also employed to improve the nanofiller’s dispersion within the polymer and compression molding is used to alter the nanofiller’s alignment.

  1. The effect of functionalization on structure and electrical conductivity of multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Lau, Cher Hon; Cervini, Raoul; Clarke, Stephen R.; Markovic, Milena Ginic; Matisons, Janis G.; Hawkins, Stephen C.; Huynh, Chi P.; Simon, George P.

    2008-01-01

    Carbon nanotubes (CNTs) are of interest in many areas of nanotechnology and used in a number of novel applications. However effective dispersion remains a problem and one solution is to functionalize the nanotubes. Any functionalization that is undertaken must preferably not influence other key properties such as strength and electrical conductivity. In this work, multi-walled CNTs are functionalized for comparison, using a range of oxidative techniques, including thermal treatment, acid reflux, and dry UV-ozonolysis. The effects of these treatments on the multi-walled carbon nanotubes (MWCNTs) and their electrical properties were characterized using a range of surface and compositional techniques. The electrical conductivity of MWCNTs was found to increase with functionalization in all cases, and dry UV-ozonolysis was shown to be the treatment technique which best increased conductivity, whilst at the same time maintaining the structural integrity of the nanotubes, even though the level of modification was less than by the other treatment methods.

  2. Polypyrrole-chitosan conductive biomaterial synchronizes cardiomyocyte contraction and improves myocardial electrical impulse propagation.

    Science.gov (United States)

    Cui, Zhi; Ni, Nathan C; Wu, Jun; Du, Guo-Qing; He, Sheng; Yau, Terrence M; Weisel, Richard D; Sung, Hsing-Wen; Li, Ren-Ke

    2018-01-01

    Background: The post-myocardial infarction (MI) scar interrupts electrical impulse propagation and delays regional contraction, which contributes to ventricular dysfunction. We investigated the potential of an injectable conductive biomaterial to restore scar tissue conductivity and re-establish synchronous ventricular contraction. Methods: A conductive biomaterial was generated by conjugating conductive polypyrrole (PPY) onto chitosan (CHI) backbones. Trypan blue staining of neonatal rat cardiomyocytes (CMs) cultured on biomaterials was used to evaluate the biocompatibility of the conductive biomaterials. Ca 2+ imaging was used to visualize beating CMs. A cryoablation injury rat model was used to investigate the ability of PPY:CHI to improve cardiac electrical propagation in the injured heart in vivo . Electromyography was used to evaluate conductivity of scar tissue ex vivo . Results: Cell survival and morphology were similar between cells cultured on biomaterials-coated and uncoated-control dishes. PPY:CHI established synchronous contraction of two distinct clusters of spontaneously-beating CMs. Intramyocardial PPY:CHI injection into the cryoablation-induced injured region improved electrical impulse propagation across the scarred tissue and decreased the QRS interval, whereas saline- or CHI-injected hearts continued to have delayed propagation patterns and significantly reduced conduction velocity compared to healthy controls. Ex vivo evaluation found that scar tissue from PPY:CHI-treated rat hearts had higher signal amplitude compared to those from saline- or CHI-treated rat heart tissue. Conclusions: The PPY:CHI biomaterial is electrically conductive, biocompatible and injectable. It improved synchronous contraction between physically separated beating CM clusters in vitro . Intra-myocardial injection of PPY:CHI following cardiac injury improved electrical impulse propagation of scar tissue in vivo .

  3. ZnO Coatings with Controlled Pore Size, Crystallinity and Electrical Conductivity

    Directory of Open Access Journals (Sweden)

    Roman SCHMACK

    2016-05-01

    Full Text Available Zinc oxide is a wide bandgap semiconductor with unique optical, electrical and catalytic properties. Many of its practical applications rely on the materials pore structure, crystallinity and electrical conductivity. We report a synthesis method for ZnO films with ordered mesopore structure and tuneable crystallinity and electrical conductivity. The synthesis relies on dip-coating of solutions containing micelles of an amphiphilic block copolymer and complexes of Zn2+ ions with aliphatic ligands. A subsequent calcination at 400°C removes the template and induces crystallization of the pore walls. The pore structure is controlled by the template polymer, whereas the aliphatic ligands control the crystallinity of the pore walls. Complexes with a higher thermal stability result in ZnO films with a higher content of residual carbon, smaller ZnO crystals and therefore lower electrical conductivity. The paper discusses the ability of different types of ligands to assist in the synthesis of mesoporous ZnO and relates the structure and thermal stability of the precursor complexes to the crystallinity and electrical conductivity of the zinc oxide.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.8634

  4. The Electrical and Thermal Conductivity of Woven Pristine and Intercalated Graphite Fiber-Polymer Composites

    Science.gov (United States)

    Gaier, James R.; Vandenburg, Yvonne Yoder; Berkebile, Steven; Stueben, Heather; Balagadde, Frederick

    2002-01-01

    A series of woven fabric laminar composite plates and narrow strips were fabricated from a variety of pitch-based pristine and bromine intercalated graphite fibers in an attempt to determine the influence of the weave on the electrical and thermal conduction. It was found generally that these materials can be treated as if they are homogeneous plates. The rule of mixtures describes the resistivity of the composite fairly well if it is realized that only the component of the fibers normal to the equipotential surface will conduct current. When the composite is narrow with respect to the fiber weave, however, there is a marked angular dependence of the resistance which was well modeled by assuming that the current follows only along the fibers (and not across them in a transverse direction), and that the contact resistance among the fibers in the composite is negligible. The thermal conductivity of composites made from less conductive fibers more closely followed the rule of mixtures than that of the high conductivity fibers, though this is thought to be an artifact of the measurement technique. Electrical and thermal anisotropy could be induced in a particular region of the structure by weaving together high and low conductivity fibers in different directions, though this must be done throughout all of the layers of the structure as interlaminar conduction precludes having only the top layer carry the anisotropy. The anisotropy in the thermal conductivity is considerably less than either that predicted by the rule of mixtures or the electrical resistivity.

  5. Electrical conductivity measurement of excised human metastatic liver tumours before and after thermal ablation.

    Science.gov (United States)

    Haemmerich, Dieter; Schutt, David J; Wright, Andrew W; Webster, John G; Mahvi, David M

    2009-05-01

    We measured the ex vivo electrical conductivity of eight human metastatic liver tumours and six normal liver tissue samples from six patients using the four electrode method over the frequency range 10 Hz to 1 MHz. In addition, in a single patient we measured the electrical conductivity before and after the thermal ablation of normal and tumour tissue. The average conductivity of tumour tissue was significantly higher than normal tissue over the entire frequency range (from 4.11 versus 0.75 mS cm(-1) at 10 Hz, to 5.33 versus 2.88 mS cm(-1) at 1 MHz). We found no significant correlation between tumour size and measured electrical conductivity. While before ablation tumour tissue had considerably higher conductivity than normal tissue, the two had similar conductivity throughout the frequency range after ablation. Tumour tissue conductivity changed by +25% and -7% at 10 Hz and 1 MHz after ablation (0.23-0.29 at 10 Hz, and 0.43-0.40 at 1 MHz), while normal tissue conductivity increased by +270% and +10% at 10 Hz and 1 MHz (0.09-0.32 at 10 Hz and 0.37-0.41 at 1 MHz). These data can potentially be used to differentiate tumour from normal tissue diagnostically.

  6. In vivo electrical conductivity imaging of a canine brain using a 3 T MREIT system

    International Nuclear Information System (INIS)

    Kim, Hyung Joong; Oh, Tong In; Kim, Young Tae; Lee, Byung Il; Woo, Eung Je; Lee, Soo Yeol; Seo, Jin Keun; Kwon, Ohin; Park, Chunjae; Kang, Byeong Teck; Park, Hee Myung

    2008-01-01

    Magnetic resonance electrical impedance tomography (MREIT) aims at producing high-resolution cross-sectional conductivity images of an electrically conducting object such as the human body. Following numerous phantom imaging experiments, the most recent study demonstrated successful conductivity image reconstructions of postmortem canine brains using a 3 T MREIT system with 40 mA imaging currents. Here, we report the results of in vivo animal imaging experiments using 5 mA imaging currents. To investigate any change of electrical conductivity due to brain ischemia, canine brains having a regional ischemic model were scanned along with separate scans of canine brains having no disease model. Reconstructed multi-slice conductivity images of in vivo canine brains with a pixel size of 1.4 mm showed a clear contrast between white and gray matter and also between normal and ischemic regions. We found that the conductivity value of an ischemic region decreased by about 10–14%. In a postmortem brain, conductivity values of white and gray matter decreased by about 4–8% compared to those in a live brain. Accumulating more experience of in vivo animal imaging experiments, we plan to move to human experiments. One of the important goals of our future work is the reduction of the imaging current to a level that a human subject can tolerate. The ability to acquire high-resolution conductivity images will find numerous clinical applications not supported by other medical imaging modalities. Potential applications in biology, chemistry and material science are also expected

  7. Relaxation and Conductivity in P3HT/PC71BM Blends As Revealed by Dielectric Spectroscopy

    DEFF Research Database (Denmark)

    Cui, Jing; Martinez-Tong, Daniel E.; Sanz, Alejandro

    2016-01-01

    The conduction mechanism and the molecular dynamics on the paradigmatic bulk heterojunction formed by poly(3-hexylthiophene) (P3HT) and phenyl-C-71-butyric acid methyl ester (PC71BM) blends have been characterized by dielectric spectroscopy. The results show that hexyl lateral chains of the polym...

  8. Influence of Electric Fields and Conductivity on Pollen Tube Growth assessed via Electrical Lab-on-Chip

    Science.gov (United States)

    Agudelo, Carlos; Packirisamy, Muthukumaran; Geitmann, Anja

    2016-01-01

    Pollen tubes are polarly growing plant cells that are able to rapidly respond to a combination of chemical, mechanical, and electrical cues. This behavioural feature allows them to invade the flower pistil and deliver the sperm cells in highly targeted manner to receptive ovules in order to accomplish fertilization. How signals are perceived and processed in the pollen tube is still poorly understood. Evidence for electrical guidance in particular is vague and highly contradictory. To generate reproducible experimental conditions for the investigation of the effect of electric fields on pollen tube growth we developed an Electrical Lab-on-Chip (ELoC). Pollen from the species Camellia displayed differential sensitivity to electric fields depending on whether the entire cell or only its growing tip was exposed. The response to DC fields was dramatically higher than that to AC fields of the same strength. However, AC fields were found to restore and even promote pollen growth. Surprisingly, the pollen tube response correlated with the conductivity of the growth medium under different AC frequencies—consistent with the notion that the effect of the field on pollen tube growth may be mediated via its effect on the motion of ions. PMID:26804186

  9. Effect of variation in the glass-former network structure on the relaxation properties of conductive Ag+ ions in AgI-based fast ion conducting glasses

    Science.gov (United States)

    Hanaya, Minoru; Nakayama, Michiko; Hatate, Atsuo; Oguni, Masaharu

    1995-08-01

    Heat capacities and ac conductivities of AgI-based fast ion conducting glasses of AgI-Ag2O-P2O5 and AgI-Ag2O-B2O3 systems with different P-O or B-O network structures but with the same AgI concentration of 1.55×104 mol m-3 were measured in the temperature range 14-400 K and in the temperature and frequency ranges 100-200 K and 10 Hz-1 MHz, respectively. The β-glass transition due to a freezing-in of the rearrangement of Ag+ ions was observed by adiabatic calorimetry for the glasses in the liquid-nitrogen temperature region, and the conductometry was suggested to see the same mode of Ag+-ion motion as the calorimetry. It was found that the development of the network structure of the glass former at constant AgI concentration resulted in the decrease of the β-glass transition temperature and the activation energy for the diffusional motion of Ag+ ions and in the increase of the heat-capacity jump associated with the glass transition. The results support the amorphous AgI aggregate model for the structure of the conductive region in the glasses with relatively high AgI compositions, indicating that Ag+-ion conductivity is mainly dominated by the degree of development of the AgI aggregate region dependent on the glass-former network structure as well as the AgI composition.

  10. Statistical properties of Joule heating rate, electric field and conductances at high latitudes

    Directory of Open Access Journals (Sweden)

    A. T. Aikio

    2009-07-01

    Full Text Available Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox and from similar sunspot conditions (about 1.5 years before the sunspot minimum providing an excellent set of data to study the MLT and Kp dependence of parameters with high temporal and spatial resolution.

    All the parameters show a clear MLT variation, which is different for low and high Kp conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for Kp≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity.

    An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (Kp<3 and Kp≥3. In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to

  11. Effect of fast-neutron irradiation on the electrical conductivity of NaKSO4 crystals

    International Nuclear Information System (INIS)

    Kassem, M.E.; El-Khatib, A.M.; El-Wahidy, E.F.; Gado, H.E.

    1987-01-01

    In recent years, the study of the physical properties of NaKSO 4 has drawn the attention of many investigators. Measurements on the electrical, thermal and elastic properties of NaKSO 4 in the temperature range 300 to 500 K show a structural phase transition at 453 K. Electrical conductivity measurements [4] on pure and doped compounds of NaKSO 4 reveal high ionic conductivity values in the high-temperature range. Order-disorder transitions and solid state kinetics in the same compound were also studied. (author)

  12. Statistical properties of Joule heating rate, electric field and conductances at high latitudes

    Directory of Open Access Journals (Sweden)

    A. T. Aikio

    2009-07-01

    Full Text Available Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox and from similar sunspot conditions (about 1.5 years before the sunspot minimum providing an excellent set of data to study the MLT and Kp dependence of parameters with high temporal and spatial resolution. All the parameters show a clear MLT variation, which is different for low and high Kp conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for Kp≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity. An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (Kp<3 and Kp≥3. In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to auroral arcs as a result of ionosphere-magnetosphere coupling, as discussed by Aikio et al. (2004 In

  13. On the electrical conductivity for the mixed-valence model with d-f correlations

    International Nuclear Information System (INIS)

    Borgiel, W.; Matlak, M.

    1984-08-01

    The static electrical conductivity of mixed-valence systems is calculated in the model of Matlak and Nolting [Solid State Commun., 47, 11 (1983); Z. Phys., B55, 103 (1984)]. The method takes into account the atomic properties more exactly than those connected with bands, and hence emphasizes the ionic aspect of the problem in some way; indeed, the calculations overestimate the atomic properties. Some results are presented in a graph. It is found that the electrical conductivity depends strongly on temperature and the electron-hole attraction constant

  14. The Relation between the Electric Conductance of Nanostructure Bridge and Friedel Sum Rule

    International Nuclear Information System (INIS)

    Kotani, Y; Shima, N; Makoshi, K

    2012-01-01

    We analyze the electric conductance through nanostructure bridges in terms of phase-shifts, which satisfy the Friedel sum rule. The phase-shifts are given by solving the eigenvalue equation obtained by extending the method applied to a single impurity problem in a metal. The local charge neutrality condition is introduced through the Friedel sum rule. It is analytically shown that the electric conductance can increase as the two electrodes separate with the condition in which the phase-shifts satisfy the Friedel sum rule. The increment of the distance between two electrodes is obtained by gradually separating interatomic distance.

  15. Analytical solution of electromagnetic radiation by a vertical electric dipole inside the earth and the effect of atmospheric electrical conductivity inhomogeneity

    Science.gov (United States)

    Mosayebidorcheh, Taha; Hosseinibalam, Fahimeh; Hassanzadeh, Smaeyl

    2017-11-01

    In this paper, the effect of atmospheric electrical conductivity on the electromagnetic waves radiated by a vertical electric dipole located in the earth, near the surface of the earth, is investigated. As far as electrical conductivity is concerned, the atmosphere is divided into three areas, in which the electrical conductivity changes with altitude. The Maxwell equations in these areas are investigated as well. Using the differential transform method, the differential equation is solved in a way that atmospheric electrical conductivity is variable. Solving the problem in these areas indicates that electrical conductivity in the middle and lower areas of atmosphere may be ignored. However, in the upper areas of atmosphere, the magnitude of the magnetic field in the ionosphere at a frequency of 10 kHz at night is five times smaller when electrical conductivity is considered compared to when it is neglected.

  16. A deterministic model for the growth of non-conducting electrical tree structures

    International Nuclear Information System (INIS)

    Dodd, S J

    2003-01-01

    Electrical treeing is of interest to the electrical generation, transmission and distribution industries as it is one of the causes of insulation failure in electrical machines, switchgear and transformer bushings. In this paper a deterministic electrical tree growth model is described. The model is based on electrostatics and local electron avalanches to model partial discharge activity within the growing tree structure. Damage to the resin surrounding the tree structure is dependent on the local electrostatic energy dissipation by partial discharges within the tree structure and weighted by the magnitudes of the local electric fields in the resin surrounding the tree structure. The model is successful in simulating the formation of branched structures without the need of a random variable, a requirement of previous stochastic models. Instability in the spatial development of partial discharges within the tree structure takes the role of the stochastic element as used in previous models to produce branched tree structures. The simulated electrical trees conform to the experimentally observed behaviour; tree length versus time and electrical tree growth rate as a function of applied voltage for non-conducting electrical trees. The phase synchronous partial discharge activity and the spatial distribution of emitted light from the tree structure are also in agreement with experimental data for non-conducting trees as grown in a flexible epoxy resin and in polyethylene. The fact that similar tree growth behaviour is found using pure amorphous (epoxy resin) and semicrystalline (polyethylene) materials demonstrate that neither annealed or quenched noise, representing material inhomogeneity, is required for the formation of irregular branched structures (electrical trees). Instead, as shown in this paper, branched growth can occur due to the instability of individual discharges within the tree structure

  17. Electrical conductivity of activated carbon-metal oxide nanocomposites under compression: a comparison study.

    Science.gov (United States)

    Barroso-Bogeat, A; Alexandre-Franco, M; Fernández-González, C; Macías-García, A; Gómez-Serrano, V

    2014-12-07

    From a granular commercial activated carbon (AC) and six metal oxide (Al2O3, Fe2O3, SnO2, TiO2, WO3 and ZnO) precursors, two series of AC-metal oxide nanocomposites were prepared by wet impregnation, oven-drying at 120 °C, and subsequent heat treatment at 200 or 850 °C in an inert atmosphere. Here, the electrical conductivity of the resulting products was studied under moderate compression. The influence of the applied pressure, sample volume, mechanical work, and density of the hybrid materials was thoroughly investigated. The DC electrical conductivity of the compressed samples was measured at room temperature by the four-probe method. Compaction assays suggest that the mechanical properties of the nanocomposites are largely determined by the carbon matrix. Both the decrease in volume and the increase in density were relatively small and only significant at pressures lower than 100 kPa for AC and most nanocomposites. In contrast, the bulk electrical conductivity of the hybrid materials was strongly influenced by the intrinsic conductivity, mean crystallite size, content and chemical nature of the supported phases, which ultimately depend on the metal oxide precursor and heat treatment temperature. The supported nanoparticles may be considered to act as electrical switches either hindering or favouring the effective electron transport between the AC cores of neighbouring composite particles in contact under compression. Conductivity values as a rule were lower for the nanocomposites than for the raw AC, all of them falling in the range of semiconductor materials. With the increase in heat treatment temperature, the trend is toward the improvement of conductivity due to the increase in the crystallite size and, in some cases, to the formation of metals in the elemental state and even metal carbides. The patterns of variation of the electrical conductivity with pressure and mechanical work were slightly similar, thus suggesting the predominance of the pressure

  18. Influence of calcium and lithium on the densification and electrical conductivity of gadolinia-doped ceria

    International Nuclear Information System (INIS)

    Porfirio, Tatiane Cristina

    2011-01-01

    In this work, the use of calcium and lithium as sintering aid to gadolinia-doped ceria was systematically investigated. The main purpose was to verify the influence of these additives on the densification and electrical conductivity of sintered ceramics. Powder compositions containing up to 1.5 mol% (metal basis) of calcium or lithium were prepared by both solid state reaction and oxalate coprecipitation methods. The main characterization techniques were thermal analyses, X-ray diffraction, scanning electron microscopy and electrical conductivity by impedance spectroscopy. Both additives promoted densification of gadolinia-doped ceria. The densification increases with increasing the additive content. Different effects on microstructure and electrical conductivity result from the method of preparation, e.g., solid state reaction or coprecipitation. Calcium addition greatly enhances the grain growth compared to lithium addition. The electrical conductivity of specimens containing a second additive is lower than that of pure gadolinia-doped ceria. Both additives influence the intergranular conductivity and favor the exudation of gadolinium out of the solid solution. (author)

  19. Multishot echo-planar MREIT for fast imaging of conductivity, current density, and electric field distributions.

    Science.gov (United States)

    Chauhan, Munish; Vidya Shankar, Rohini; Ashok Kumar, Neeta; Kodibagkar, Vikram D; Sadleir, Rosalind

    2018-01-01

    Magnetic resonance electrical impedance tomography (MREIT) sequences typically use conventional spin or gradient echo-based acquisition methods for reconstruction of conductivity and current density maps. Use of MREIT in functional and electroporation studies requires higher temporal resolution and faster sequences. Here, single and multishot echo planar imaging (EPI) based MREIT sequences were evaluated to see whether high-quality MREIT phase data could be obtained for rapid reconstruction of current density, conductivity, and electric fields. A gel phantom with an insulating inclusion was used as a test object. Ghost artifact, geometric distortion, and MREIT correction algorithms were applied to the data. The EPI-MREIT-derived phase-projected current density and conductivity images were compared with simulations and spin-echo images as a function of EPI shot number. Good agreement among measures in simulated, spin echo, and EPI data was achieved. Current density errors were stable and below 9% as the shot number decreased from 64 to 2, but increased for single-shot images. Conductivity reconstruction relative contrast ratios were stable as the shot number decreased. The derived electric fields also agreed with the simulated data. The EPI methods can be combined successfully with MREIT reconstruction algorithms to achieve fast imaging of current density, conductivity, and electric field. Magn Reson Med 79:71-82, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  20. Electrical conductivity of H2O-NaCl fluids to 10 kbar

    Science.gov (United States)

    Sinmyo, R.; Keppler, H.

    2016-12-01

    Magnetotelluric studies often reveal zones of elevated electrical conductivity in the mantle wedge above subducting slabs, in the deep crust below fold belts, or below active volcanoes. Since both aqueous fluids and hydrous silivate melts may be highly conductive, they may both account for these observations. Distinguishing between these two posssibilities, however, is difficult. One reason for this problem is that while there are very good conductivity data for silicate melts, such data do not exist for aqueous fluids under the relevant conditions of pressure, temperature and solute concentration. Most crustal and mantle fluids likely contain some NaCl, which greatly enhances conductivity due to its partial dissociation into Na+ and Cl-. We therefore studied the electrical conductivity of 0.01, 0.1 and 1 m NaCl solutions in water to 10 kbar and 600 °C. The measurements were carried out in externally-heated diamond cells containing two gaskets separated by an insulating ring of diamond, following a method described by Ni et al. (2014). The two gaskets were used as electrodes and full impedance spectra were measured from 30 Hz to 10 MHz using a Solartron 1260 impedance analyzer. Electrical conductivity was generally found to increase with pressure temperature, and fluid density. The conductivity increase observed upon variation of NaCl concentration from 0.1m to 1m was smaller than from 0.01m to 0.1m, which reflects the reduced degree of dissociation at high NaCl concentration. In general, the data show that already a very small fraction of NaCl-bearing aqueous fluid is sufficient to enhance bulk conductivities to values that would be expected for a high degree of partial melting. Accordingly, aqueous fluids may be distinguished from hydrous melts by comparing magnetotelluric and seismic data. H2O-NaCl fluids may enhance electrical conductivities with little disturbance of vp or vp/vs ratios.

  1. Correlation of Electrical and Swelling Properties with Nano Free Volume Structure of Conductive Silicone Rubber Composites

    International Nuclear Information System (INIS)

    Abd-El Salam, M.H.; El-Gamal, S.; Abd El-Maqsoud, D.M.; Mohsen, M.

    2013-01-01

    The present study focuses on finding a correlation between the positron annihilation parameters in silicone rubber based on Poly dimethyl siloxane (PDMS) composites loaded with different conductive fillers and their swelling and electrical properties. Four types of conductive fillers have been used in this study: carbon black, graphite, copper, and nickel powders. The maximum degree of swelling Q m %, the penetration rate, P, as well as the diffusion coefficient, D, decrease with increasing the filler content due to the reduction of the size of free volume, as observed through a decrease of the probability of ortho-positronium (o-Ps) formation I 3 and the o-Ps lifetime Τ 3 , representing the size of free volume measured by the positron annihilation lifetime technique (PAL). The electrical conductivity ln (Σ) is positively correlated with the probability of free annihilation of positrons at interfaces I 2 , thus suggesting an increase in the electron density with the filler content. The activation energy of conduction, E a , is found to decrease with the increase in the loading of conductive filler and the particle size of the filler. A correlation between the free-volume V f , and the d.c. electrical conductivity ln (Σ) is found to be in accordance with Miyamoto and Shibayma model of ion conduction.

  2. Superposition approach for description of electrical conductivity in sheared MWNT/polycarbonate melts

    Directory of Open Access Journals (Sweden)

    M. Saphiannikova

    2012-06-01

    Full Text Available The theoretical description of electrical properties of polymer melts, filled with attractively interacting conductive particles, represents a great challenge. Such filler particles tend to build a network-like structure which is very fragile and can be easily broken in a shear flow with shear rates of about 1 s–1. In this study, measured shear-induced changes in electrical conductivity of polymer composites are described using a superposition approach, in which the filler particles are separated into a highly conductive percolating and low conductive non-percolating phases. The latter is represented by separated well-dispersed filler particles. It is assumed that these phases determine the effective electrical properties of composites through a type of mixing rule involving the phase volume fractions. The conductivity of the percolating phase is described with the help of classical percolation theory, while the conductivity of non-percolating phase is given by the matrix conductivity enhanced by the presence of separate filler particles. The percolation theory is coupled with a kinetic equation for a scalar structural parameter which describes the current state of filler network under particular flow conditions. The superposition approach is applied to transient shear experiments carried out on polycarbonate composites filled with multi-wall carbon nanotubes.

  3. Oxygen vacancies effect on ionic conductivity and relaxation phenomenon in undoped and Mn doped PZN-4.5PT single crystals

    International Nuclear Information System (INIS)

    Kobor, Diouma; Guiffard, Benoit; Lebrun, Laurent; Hajjaji, Abdelowahed; Guyomar, Daniel

    2007-01-01

    AC-impedance spectroscopic studies in the temperature range 550-700 deg. C are carried out on undoped and Mn doped PZN-PT single crystals grown by the flux method. The variation of dielectric permittivity with temperature at different frequencies shows normal ferroelectric and relaxor-like dependence for the doped and undoped crystals, respectively. Temperature-dependent spectroscopic modulus plots reveal a much broader peak for PZN-4.5PT + 1%Mn compared with that for PZN-4.5PT, which is different from the dielectric behaviour of the doped one. Complex modulus imaginary part (Z-prime) versus real part (Z') plots fit well with one semicircle thus indicating only bulk contribution. The relaxation observed in the spectroscopic plots was assigned to mobile relaxor species such as oxygen vacancies and ions. No such relaxation could be observed for PZN-4.5PT + 1%Mn in the dielectric measurements. For both undoped and Mn doped crystals, the conduction behaviour was modelled by the universal dynamic response equation and by the NTC (negative temperature coefficient) materials resistance-temperature behaviour. A large difference in behaviour was found between the two single crystals such as the thermistor coefficients and the activation energy values, which could explain the increase in the thermal stability observed in the Mn doped PZN-PT single crystals by many studies

  4. Relaxed electric dipole moments of polar molecules interacting with a slow positron: H{sub 2}O and CH{sub 3}X (X=F, Cl, Br)

    Energy Technology Data Exchange (ETDEWEB)

    Assafrao, Denise; Mohallem, Jose R, E-mail: rachid@fisica.ufmg.b [Laboratorio de Atomos e Moleculas Especiais, Departamento de FIsica, ICEx, Universidade Federal de Minas Gerais, PO Box 702, 30123-970, Belo Horizonte, MG (Brazil)

    2010-08-14

    The variation in the electric dipole moments of H{sub 2}O, CH{sub 3}F, CH{sub 3}Cl and CH{sub 3}Br as their geometries relax due to interaction with a positron is evaluated. The results are in good agreement with a recently observed empirical dependence of the positron binding energy on molecular properties (Danielson et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 235203). For binding energies larger than 100 meV relaxation could alter significantly the analysis of the binding, but it is in the prospect of generating effective potentials for positron scattering by molecules that the effect can be more important.

  5. Novel electrical transport properties in conducting polymers such as polythiophene and Poly(3-Methylthiophene)

    International Nuclear Information System (INIS)

    Kazama, Shigeo; Masubuchi, Shin-ichi; Matsuyama, Tomochika; Matsushita, Rokuji.

    1994-01-01

    Electric transport properties in most of the conducting organic polymers have provided a riddle that prevents a thorough physical understanding of the conduction mechanism. Major difficulties for approaching the most substantial aspect in the electrical transport properties underlie in complicated higher order structure inherent to polymeric materials consisting of crystalline regions entangled with disordered amorphous regions. In order to clearly understand the origin of the metallic nature of conducting polymers, we have to extract the proper transport properties characteristics of the ordered crystalline regions. We have made a series of experimental studies of the transport properties in conductive polythiophene and poly(3-methylthiophene) obtained with the electrochemical polymerization. For polythiophene, we have investigated both the as-grown samples and the ones that contain controlled amount of dopant species exchanged after the neutralization aiming to see the effect of dopant concentration on the transport properties. (author)

  6. Research of Electrical Conductivity Measurement System for Mine Bursting Water Based on Dual Frequency Method

    Directory of Open Access Journals (Sweden)

    Zhou Mengran

    2016-01-01

    Full Text Available This paper presents a double frequency conductivity measurement method for measuring mine bursting water, to solve the capacitance effect of the conductivity sensor itself has the help. The core controller of the system is the single chip microcomputer ATMEGA128. This paper introduces the basic principle of the measurement of the existing problems and the dual frequency measurement method, and then introduces and analyzes the hardware. To test and analyze the collected data, the double frequency method is found to have good stability and accuracy in the measurement of the electrical conductivity of mine inrush water. It is proved that the method and the system design of the hardware circuit can accurately measure the electric conductivity of the mine inrush water source.

  7. Electrical properties and conduction mechanisms of Ru-based thick-film (cermet) resistors

    International Nuclear Information System (INIS)

    Pike, G.E.; Seager, C.H.

    1977-01-01

    This paper presents an experimental study of the electrical conduction mechanisms in thick-film (cermet) resistor. The resistors were made from one custom and three commercially formulated inks with sheet resistivities ranging from 10 2 to 10 6 Ω/D 7 Alembertian in decade increments. Their microstructure and composition have been examined using optical and scanning electron microscopy, electron microprobe analysis, x-ray diffraction, and various chemical analyses. This portion of our study shows that the resistors are heterogeneous mixtures of metallic metal oxide particles (approx.4 x 10 -5 cm in diameter) and a lead silicate glass. The metal oxide particles are ruthenium containing pyrochlores, and are joined to form a continuous three-dimensional network of chain segments. The principal experimental work reported here is an extensive study of the electrical transport properties of the resistors. The temperature dependence of conductance has been measured from 1.2 to 400 K, and two features common to all resistors are found. There is a pronounced decrease in conductance at low temperatures and a shallow maximum at several hundred Kelvin. Within the same range of temperatures the reversible conductance as a function of electric field from 0 to 28 kV/cm has been studied. The resistors are non-Ohmic at all temperatures, but particularly at cryogenic temperatures for low fields. At higher fields the conductance shows a linear variation with electric field. The thick-film resistors are found to have a small dielectric constant and a (nearly) frequency-independent conductance from dc to 50 MHz. The magnetoresistance to 100 kG, the Hall mobility, and the Seebeck coefficient of most of the resistors have been measured and discovered to be quite small. Many of the electrical transport properties have also been determined for the metal oxide particles which were extracted from the fired resistors

  8. Electronic energy gap of molecular hydrogen from electrical conductivity measurements at high shock pressures

    Science.gov (United States)

    Nellis, W. J.; Mitchell, A. C.; Mccandless, P. C.; Erskine, D. J.; Weir, S. T.

    1992-01-01

    Electrical conductivities were measured for liquid D2 and H2 shock compressed to pressures of 10-20 GPa (100-200 kbar), molar volumes near 8 cu cm/mol, and calculated temperatures of 2900-4600 K. The semiconducting energy gap derived from the conductivities is 12 eV, in good agreement with recent quasi-particle calculations and with oscillator frequencies measured in diamond-anvil cells.

  9. Conductance fluctuations and distribution at metal-insulator transition induced by electric field in disordered chain

    International Nuclear Information System (INIS)

    Senouci, Khaled

    2000-08-01

    A simple Kronig-Penney model for 1D mesoscopic systems with δ peak potentials is used to study numerically the influence of a constant electric field on the conductance fluctuations and distribution at the transition. We found that the conductance probability distribution has a system-size independent form with large fluctuations in good agreement with the previous works in 2D and 3D systems. (author)

  10. Electrical conductivity of a fully ionized plasma in a magnetic field

    International Nuclear Information System (INIS)

    Vaucher, B.; Vaclavik, J.; Schneider, H.

    1975-01-01

    In this experimental work the authors have investigated the electrical conductivity of a homogeneous fully ionized plasma in a homogeneous magnetic field. In particular, the conductivity perpendicular to the magnetic field was studied by means of the magnetoacoustic resonance for different values of the parameter ωsub(c)/γsub(ei) where ωsub(c) is the electron cyclotron frequency and γsub(ei) is the collision frequency between electrons and ions. (Auth.)

  11. Infrared transparency and electrical conductivity of non-stoichiometric InxOy films

    International Nuclear Information System (INIS)

    Joseph, Shay; Berger, Shlomo

    2010-01-01

    In an effort to achieve both high infrared transparency and electrical conductivity, In x O y films having different oxygen atomic fractions, ranging from 0.27 to 0.6 were prepared. From AC electrical measurements it was determined that conductivity of In x O y films, having oxygen atomic fraction near 0.6, is governed by the hopping conduction mechanism via energy states located in the band gap. Conductivity of In x O y films having non-stoichiometric compositions was found to be governed by the free band conduction mechanism. The conduction activation energy was decreased from about 0.47 eV to about 0.02 eV as the deviation of the oxygen atomic fraction from the stoichiometric value of 0.6 was increased. The dielectric function of the films was determined by applying the Drude-Lorentz model to ellipsometric measurements in the infrared and visible wavelengths. In the visible range, the major source for optical transmission loss is interband absorption, which was modeled by the Lorentz model. In the infrared range, optical absorption was measured and attributed to the presence of free charge carriers according to the Drude model. Fitting the model to the optical measurements required a correction factor, which was correlated with the films polarizability. In order to determine the optimal tradeoff between optical transparency in the infrared and electrical conductivity, which were found to be affected mainly by the oxygen concentration in the films, a figure of merit parameter was established. It was found that by introducing non-stoichiometry in the form of oxygen deficiency, the electrical conductivity was improved by as much as two orders of magnitude while the infrared transparency was decreased by no more than 30% with respect to stoichiometric In 2 O 3 films.

  12. Electrical and optical performance of transparent conducting oxide films deposited by electrostatic spray assisted vapour deposition.

    Science.gov (United States)

    Hou, Xianghui; Choy, Kwang-Leong; Liu, Jun-Peng

    2011-09-01

    Transparent conducting oxide (TCO) films have the remarkable combination of high electrical conductivity and optical transparency. There is always a strong motivation to produce TCO films with good performance at low cost. Electrostatic Spray Assisted Vapor Deposition (ESAVD), as a variant of chemical vapour deposition (CVD), is a non-vacuum and low-cost deposition method. Several types of TCO films have been deposited using ESAVD process, including indium tin oxide (ITO), antimony-doped tin oxide (ATO), and fluorine doped tin oxide (FTO). This paper reports the electrical and optical properties of TCO films produced by ESAVD methods, as well as the effects of post treatment by plasma hydrogenation on these TCO films. The possible mechanisms involved during plasma hydrogenation of TCO films are also discussed. Reduction and etching effect during plasma hydrogenation are the most important factors which determine the optical and electrical performance of TCO films.

  13. Effect of Microstructure on Electrical Conductivity of Nickel-Base Superalloys

    Science.gov (United States)

    Nagarajan, Balasubramanian; Castagne, Sylvie; Annamalai, Swaminathan; Fan, Zheng; Chan, Wai Luen

    2017-08-01

    Eddy current spectroscopy is one of the promising non-destructive methods for residual stress evaluation along the depth of subsurface-treated nickel-base superalloys, but it is limited by its sensitivity to microstructure. This paper studies the influence of microstructure on the electrical conductivity of two nickel-base alloys, RR1000 and IN100. Different microstructures were attained using heat treatment cycles ranging from solution annealing to aging, with varying aging time and temperature. Eddy current conductivity was measured using conductivity probes of frequencies ranging between 1 and 5 MHz. Qualitative and quantitative characterization of the microstructure was performed using optical and scanning electron microscopes. For the heat treatment conditions between the solution annealing and the peak aging, the electrical conductivity of RR1000 increased by 6.5 pct, which is duly substantiated by the corresponding increase in hardness (12 pct) and the volume fraction of γ' precipitates (41 pct). A similar conductivity rise of 2.6 pct for IN100 is in agreement with the increased volume fraction of γ' precipitates (12.5 pct) despite an insignificant hardening between the heat treatment conditions. The observed results with RR1000 and IN100 highlight the sensitivity of electrical conductivity to the minor microstructure variations, especially the volume fraction of γ' precipitates, within the materials.

  14. Relationship between cotton yield and soil electrical conductivity, topography, and landsat imagery

    Science.gov (United States)

    Understanding spatial and temporal variability in crop yield is a prerequisite to implementing site-specific management of crop inputs. Apparent soil electrical conductivity (ECa), soil brightness, and topography are easily obtained data that can explain yield variability. The objectives of this stu...

  15. Cell percolation model for electrical conduction of granular superconducting composites. 2

    International Nuclear Information System (INIS)

    Horvath, G.; Bankuti, J.

    1990-01-01

    The percolation of the electrical conductivity of the uniform cells is studied in an in-situ elongated granular superconducting composite on the basis of the uniform cell model improved previously. The critical temperatures are determined in the macroscopic superconducting state of the two- and the three-dimensional composites. (author)

  16. Electric conductivity of salt melts containing KCL, KF and K2TaF7

    International Nuclear Information System (INIS)

    Agulyanskij, A.I.; Stangrit, P.T.; Konstantinov, V.I.

    1978-01-01

    Given are electric conductivity measurement results depending on the temperature and composition of the molten KF-K 2 TaF 7 , KCl-K 2 TaF 7 systems and also melts close in their composition to industrial electrolytes, KCl-KF (in mass ratio of 2:1) with addition of K 2 TaF 7 up to 25 mass%. Presented are electric conductivity molecular isotherms of the KF-K 2 TaF 7 , KCl-K 2 TaF 7 systems at 800 deg C and specific electric conductivity dependence of KCl-KF-K 2 TaF 7 melts on K 2 TaF 7 composition at 800 deg C and 900 deg C. Proceeding from the shape of molecular and specific electric conductivity isotherms a conclusion is made about existence of the following tantalum-containing ions: TaF 7 2- , TaF 6 - and TaF 6 Cl 2- in the investigated melts

  17. Electrical conductivity of molten ZnCl{sub 2} at temperature as high as 1421 K

    Energy Technology Data Exchange (ETDEWEB)

    Salyulev, Alexander B.; Potapov, Alexei M. [RAS Ural Branch, Ekaterinburg. (Russian Federation) Institute of High-Temperature Electrochemistry

    2015-07-01

    The electrical conductivity of molten ZnCl{sub 2} was measured in a wide temperature range (ΔT=863 K) to a temperature as high as 1421 K that is 417 degrees above the boiling point of the salt. At the temperature maximum of the own vapor pressure of the salt reached several megapascals.

  18. The role of the salt electrolyt on the electrical conductive properties of a polymeric bipolar membrane

    NARCIS (Netherlands)

    Alcaraz, Antonio; Wilhelm, F.G.; Wessling, Matthias; Ramirez, Patricio

    2001-01-01

    We have studied the contribution of the salt electrolyte to the electrical conductive characteristics of a bipolar membrane. We present first a critical analysis of previous theoretical approaches, and discuss the limits of validity. Experimental current-voltage curves of several commercial bipolar

  19. Couette flow of a hydro-magnetic electrically conducting fluid with ...

    African Journals Online (AJOL)

    Numerical solution of the problem of Couette flow of a hydromagnetic electrically conducting fluid has been obtained where the temperature of the fluid is assumed to vary exponentially. Results obtained for the flow velocity, temperature, skin friction and rate of heat transfer indicate that the temperature is higher when the ...

  20. Structure, temperature and frequency dependent electrical conductivity of oxidized and reduced electrochemically exfoliated graphite

    Science.gov (United States)

    Radoń, Adrian; Włodarczyk, Patryk; Łukowiec, Dariusz

    2018-05-01

    The article presents the influence of reduction by hydrogen in statu nascendi and modification by hydrogen peroxide on the structure and electrical conductivity of electrochemically exfoliated graphite. It was confirmed that the electrochemical exfoliation can be used to produce oxidized nanographite with an average number of 25 graphene layers. The modified electrochemical exfoliated graphite and reduced electrochemical exfoliated graphite were characterized by high thermal stability, what was associated with removing of labile oxygen-containing groups. The presence of oxygen-containing groups was confirmed using Fourier-transform infrared spectroscopy. Influence of chemical modification by hydrogen and hydrogen peroxide on the electrical conductivity was determined in wide frequency (0.1 Hz-10 kHz) and temperature range (-50 °C-100 °C). Material modified by hydrogen peroxide (0.29 mS/cm at 0 °C) had the lowest electrical conductivity. This can be associated with oxidation of unstable functional groups and was also confirmed by analysis of Raman spectra. The removal of oxygen-containing functional groups by hydrogen in statu nascendi resulted in a 1000-fold increase in the electrical conductivity compared to the electrochemical exfoliated graphite.

  1. Magnetic susceptibility and electrical conductivity of metallic dental materials and their impact on MR imaging artifacts

    Czech Academy of Sciences Publication Activity Database

    Starčuková, Jana; Starčuk jr., Zenon; Hubálková, H.; Linetskiy, I.

    2008-01-01

    Roč. 24, č. 6 (2008), s. 715-723 ISSN 0109-5641 R&D Projects: GA MZd NR8110 Institutional research plan: CEZ:AV0Z20650511 Keywords : metallic dental materials * dental alloys * amalgams * MR imaging * magnetic susceptibility * electric conductivity * image artifact Subject RIV: FF - HEENT, Dentistry Impact factor: 2.941, year: 2008

  2. Compressive stress-electrical conductivity characteristics of multiwall carbon nanotube networks

    Czech Academy of Sciences Publication Activity Database

    Slobodian, P.; Říha, Pavel; Lengálová, A.; Sáha, P.

    2011-01-01

    Roč. 46, č. 9 (2011), s. 3186-3190 ISSN 0022-2461 R&D Projects: GA AV ČR IAA200600803 Institutional research plan: CEZ:AV0Z20600510 Keywords : carbon nanotube network * compression * electrical conductivity * stress sensor Subject RIV: BK - Fluid Dynamics Impact factor: 2.015, year: 2011

  3. Inversion of soil electrical conductivity data to estimate layered soil properties

    Science.gov (United States)

    CBulk apparent soil electrical conductivity (ECa) sensors respond to multiple soil properties, including clay content, water content, and salt content (i.e., salinity). They provide a single sensor value for an entire soil profile down to a sensor-dependent measurement depth, weighted by a nonlinear...

  4. Music through the Skin--Simple Demonstration of Human Electrical Conductivity

    Science.gov (United States)

    Vollmer, M.; Möllmann, K. P.

    2016-01-01

    The conduction of electricity is an important topic for any basic physics course. Issues of safety often results in teacher demonstration experiments in front of the class or in extremely simple though--for students--not really fascinating (not to say boring) hands on activities for everybody using 1.5 V batteries, cables and light bulbs etc. Here…

  5. Carbon nanotube-coated silicone as a flexible and electrically conductive biomedical material

    International Nuclear Information System (INIS)

    Matsuoka, Makoto; Akasaka, Tsukasa; Totsuka, Yasunori; Watari, Fumio

    2012-01-01

    Artificial cell scaffolds that support cell adhesion, growth, and organization need to be fabricated for various purposes. Recently, there have been increasing reports of cell patterning using electrical fields. We fabricated scaffolds consisting of silicone sheets coated with single-walled (SW) or multi-walled (MW) carbon nanotubes (CNTs) and evaluated their electrical properties and biocompatibility. We also performed cell alignment with dielectrophoresis using CNT-coated sheets as electrodes. Silicone coated with 10 μg/cm 2 SWCNTs exhibited the least sheet resistance (0.8 kΩ/sq); its conductivity was maintained even after 100 stretching cycles. CNT coating also improved cell adhesion and proliferation. When an electric field was applied to the cell suspension introduced on the CNT-coated scaffold, the cells became aligned in a pearl-chain pattern. These results indicate that CNT coating not only provides electro-conductivity but also promotes cell adhesion to the silicone scaffold; cells seeded on the scaffold can be organized using electricity. These findings demonstrate that CNT-coated silicone can be useful as a biocompatible scaffold. - Highlights: ► We fabricated a CNT-coated silicone which has conductivity and biocompatibility. ► The conductivity was maintained after 100 cycles of stretching. ► CNT coatings enabled C2C12 cells adhere to the silicone surface. ► Cells were aligned with dielectrophoresis between CNT-coated silicone surfaces.

  6. Conductive plastic film electrodes for Pulsed Electric Field (PEF) treatment : A proof of principle

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Boxtel, L.B.J. van; Hatt, V.; Wouters, P.C.; Coronel, P.; Ferreira, J.A.

    2010-01-01

    Nowadays Pulsed Electric Field (PEF) treatment of food needs to be performed prior to packaging, either hygienic or aseptic packaging is necessary. New techniques for PEF treatment after packaging can be considered when plastic conductive (film) electrodes can be integrated within the package, so

  7. Electrical conductivity of compacts of graphene, multi-wall carbon nanotubes, carbon black, and graphite powder

    NARCIS (Netherlands)

    Marinho, B.; Gomes Ghislandi, M.; Tkalya, E.; Koning, C.E.; With, de G.

    2012-01-01

    The electrical conductivity of different carbon materials (multi-walled carbon nanotubes, graphene, carbon black and graphite), widely used as fillers in polymeric matrices, was studied using compacts produced by a paper preparation process and by powder compression. Powder pressing assays show that

  8. Magnetoresistance effects associated with various electric conduction mechanisms in nanostructured [C/FeCo]n multilayers

    Czech Academy of Sciences Publication Activity Database

    Zeng, Y.P.; Liu, Z.W.; Mikmeková, Eliška

    2017-01-01

    Roč. 421, January (2017), s. 39-43 ISSN 0304-8853 Institutional support: RVO:68081731 Keywords : magnetoresistance * thin film * microstructure * conduction regime Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Coating and films Impact factor: 2.630, year: 2016

  9. Thermal battery. [solid metal halide electrolytes with enhanced electrical conductance after a phase transition

    Science.gov (United States)

    Carlsten, R.W.; Nissen, D.A.

    1973-03-06

    The patent describes an improved thermal battery whose novel design eliminates various disadvantages of previous such devices. Its major features include a halide cathode, a solid metal halide electrolyte which has a substantially greater electrical conductance after a phase transition at some temperature, and a means for heating its electrochemical cells to activation temperature.

  10. Improved theory of time domain reflectometry with variable coaxial cable length for electrical conductivity measurements

    Science.gov (United States)

    Although empirical models have been developed previously, a mechanistic model is needed for estimating electrical conductivity (EC) using time domain reflectometry (TDR) with variable lengths of coaxial cable. The goals of this study are to: (1) derive a mechanistic model based on multisection tra...

  11. Electrical conductivity measurements from the GISP2 and GRIP Greenland ice cores

    DEFF Research Database (Denmark)

    Dahl-Jensen, Dorthe; Clausen, Henrik Brink; Taylor, K. C.

    1993-01-01

    . Here we present electrical conductivity records for the Greenland Ice Sheet Project 2 (GISP2) and Greenland Ice-core Project (GRIP) ice cores, drilled 28 km apart to enable direct comparison of the results. The upper parts of both records are consistent with previous evidence from other Greenland cores...

  12. Vertex corrections to the mean-field electrical conductivity in disordered electron systems

    Czech Academy of Sciences Publication Activity Database

    Pokorný, Vladislav; Janiš, Václav

    2013-01-01

    Roč. 25, č. 17 (2013), "175502-1"-"175502-10" ISSN 0953-8984 Institutional support: RVO:68378271 Keywords : disordered electron systems * electrical conductivity * vertex corrections Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.223, year: 2013

  13. Electrical conductivity of molten ZnCl2 at temperature as high as 1421 K

    International Nuclear Information System (INIS)

    Salyulev, Alexander B.; Potapov, Alexei M.

    2015-01-01

    The electrical conductivity of molten ZnCl 2 was measured in a wide temperature range (ΔT=863 K) to a temperature as high as 1421 K that is 417 degrees above the boiling point of the salt. At the temperature maximum of the own vapor pressure of the salt reached several megapascals.

  14. Development of a LSSVM-GC model for estimating the electrical conductivity of ionic liquids

    DEFF Research Database (Denmark)

    Gharagheizi, Farhad; Ilani-Kashkouli, Poorandokht; Sattari, Mehdi

    2014-01-01

    In this communication, an extensive set of 1077 experimental electrical conductivity data for 54 ionic liquids (ILs) was collected from 21 different literature sources. Using this dataset, a reliable least square support vector machine-group contribution (LSSVM-GC) model has been developed, which...

  15. Estimation of the electric conductivity from scalp measurements: Feasibility and application to source localization

    NARCIS (Netherlands)

    van Burik, M.J.; Peters, M.J.

    2000-01-01

    Objectives: The accuracy of electrical impedance tomography was investigated. - Methods: The conductivities of the different compartments of the volume conductor were estimated by utilizing the boundary element method. The approach was tested for realistic head models with either 3 or 4

  16. Model of electrical conductivity of skeletal muscle based on tissue structure

    NARCIS (Netherlands)

    Gielen, F.L.H.; Cruts, H.E.P.; Alberts, B.A.; Boon, K.L.; Wallinga, W.; Boom, H.B.K.

    1986-01-01

    Recent experiments carried out in our laboratory with the four-electrode method showed that the electrical conductivity of skeletal muscle tissue depends on the frequency of the injected current and the distance between the current electrodes. A model is proposed in order to study these effects. The

  17. A Simple Demonstration of the High-Temperature Electrical Conductivity of Glass

    Science.gov (United States)

    Chiaverina, Chris

    2014-01-01

    We usually think of glass as a good electrical insulator; this, however, is not always the case. There are several ways to show that glass becomes conducting at high temperatures, but the following approach, devised by Brown University demonstration manager Gerald Zani, may be one of the simplest to perform.

  18. Matrix diffusion studies by electrical conductivity methods. Comparison between laboratory and in-situ measurements

    International Nuclear Information System (INIS)

    Ohlsson, Y.; Neretnieks, I.

    1998-01-01

    Traditional laboratory diffusion experiments in rock material are time consuming, and quite small samples are generally used. Electrical conductivity measurements, on the other hand, provide a fast means for examining transport properties in rock and allow measurements on larger samples as well. Laboratory measurements using electrical conductivity give results that compare well to those from traditional diffusion experiments. The measurement of the electrical resistivity in the rock surrounding a borehole is a standard method for the detection of water conducting fractures. If these data could be correlated to matrix diffusion properties, in-situ diffusion data from large areas could be obtained. This would be valuable because it would make it possible to obtain data very early in future investigations of potentially suitable sites for a repository. This study compares laboratory electrical conductivity measurements with in-situ resistivity measurements from a borehole at Aespoe. The laboratory samples consist mainly of Aespoe diorite and fine-grained granite and the rock surrounding the borehole of Aespoe diorite, Smaaland granite and fine-grained granite. The comparison shows good agreement between laboratory measurements and in-situ data

  19. Standardization of soil apparent electrical conductivity using multi-temporal surveys across multiple production fields

    Science.gov (United States)

    Apparent soil electrical conductivity (ECa) is an efficient technique for understanding within-field variability of physical and chemical soil characteristics. Commercial devices are readily available for collecting ECa on whole fields and used broadly for crop management in precision agriculture; h...

  20. Optimization routes for high electrical conductivity of polypyrrole nanotubes prepared in presence of methyl orange

    Czech Academy of Sciences Publication Activity Database

    Kopecký, D.; Varga, M.; Prokeš, J.; Vrňata, M.; Trchová, Miroslava; Kopecká, J.; Václavík, M.

    2017-01-01

    Roč. 230, August (2017), s. 89-96 ISSN 0379-6779 R&D Projects: GA ČR(CZ) GA16-02787S; GA ČR(CZ) GA17-04109S Institutional support: RVO:61389013 Keywords : polypyrrole * electrical conductivity * nanotube Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 2.435, year: 2016