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Sample records for dependent electrical properties

  1. Temperature Dependent Electrical Properties of PZT Wafer

    Science.gov (United States)

    Basu, T.; Sen, S.; Seal, A.; Sen, A.

    2016-04-01

    The electrical and electromechanical properties of lead zirconate titanate (PZT) wafers were investigated and compared with PZT bulk. PZT wafers were prepared by tape casting technique. The transition temperature of both the PZT forms remained the same. The transition from an asymmetric to a symmetric shape was observed for PZT wafers at higher temperature. The piezoelectric coefficient (d 33) values obtained were 560 pc/N and 234 pc/N, and the electromechanical coupling coefficient (k p) values were 0.68 and 0.49 for bulk and wafer, respectively. The reduction in polarization after fatigue was only ~3% in case of PZT bulk and ~7% for PZT wafer.

  2. Stress dependent vector magnetic properties in electrical steel

    Energy Technology Data Exchange (ETDEWEB)

    Ktena, Aphrodite, E-mail: aktena@teihal.gr [Department of Electrical Engineering, TEI of Chalkida, Psachna, Evia 34400 (Greece); Davino, Daniele; Visone, Ciro [Engineering Department, University of Sannio (Italy); Hristoforou, Evangelos [Laboratory of Metallurgy, National Technical University of Athens (Greece)

    2014-02-15

    The dependence of macroscopic magnetic properties on applied and residual stresses is promising for development of new magnetic non-destructive evaluation techniques in ferrous materials. The reliability of AC magnetometry, in determining the effect of strain on magnetic macroscopic parameters, is evaluated against scalar and vector Vibrating Sample Magnetometer measurements on strained electrical steel samples after unloading. Hysteresis loops have been measured at 0°, 30°, 45°, 60° and 90° to the direction of the applied stress. Vector magnetic properties reveal a stress-related anisotropy component, which increases with strain and deteriorates after fracture. The effect of residual stress on the saturation and remanent magnetization, as well as the differential susceptibility, is discussed with respect to data from AC magnetometry at 0.1 Hz. The results of the latter are representative of the magnetic configuration of the material under test and make it a promising candidate for NDE applications in steels.

  3. Thermal dependence of passive electrical properties of lizard muscle fibres.

    Science.gov (United States)

    Adams, B A

    1987-11-01

    1. The thermal dependence of passive electrical properties was determined for twitch fibres from the white region of the iliofibularis (IF) muscle of Anolis cristatellus (15-35 degrees C) and Sceloporus occidentalis (15-40 degrees C), and for twitch fibres from the white (15-45 degrees C) and red (15-40 degrees C) regions of the IF of Dipsosaurus dorsalis. These species differ in thermal ecology, with Anolis being the least thermophilic and Dipsosaurus the most thermophilic. 2. Iliofibularis fibres from the three species reacted similarly to changing temperature. As temperature was increased, input resistance (Rin) decreased (average R10 = 0.7), length constant (L) decreased (average R10 = 0.9), time constant (tau) decreased (average R10 = 0.8), sarcoplasmic resistivity (Rs) decreased (average R10 = 0.8) and apparent membrane resistance (Rm) decreased (average R10 = 0.7). In contrast, apparent membrane capacitance (Cm) increased with increasing temperature (average R10 = 1.3). 3. Rin, L, tau and apparent Rm were lowest in fibres from Anolis (the least thermophilic species) and highest in fibres from Dipsosaurus (the most thermophilic species). Anolis had the largest and Dipsosaurus the smallest diameter fibres (126 and 57 micron, respectively). Apparent Cm was highest in fibres from Sceloporus, which had fibres of intermediate diameter (101 micron). Rs did not differ significantly among species. 4. The effect of temperature on the passive electrical properties of these lizard fibres was similar to that reported for muscle fibres from other ectothermic animals (crustaceans, insects, fish and amphibians) but qualitatively different from that reported for some mammalian (cat tenuissimus, goat intercostal) fibres. The changes that occur in the passive electrical properties render the fibres less excitable as temperature increases.

  4. Temperature dependence of the electrical properties of hydrogen titanate nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Diego C. B.; Brandão, Frederico D.; Krambrock, Klaus; Ferlauto, Andre S. [Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais 31270-901 (Brazil); Fonseca, Fabio C. [Instituto de Pesquisas Energéticas e Nucleares, IPEN/CNEN-SP, 05508-000 São Paulo (Brazil)

    2014-11-14

    The temperature dependence of the electrical properties of hydrogen-rich titanate nanotubes (H-TNTs) in the 90–270 °C range was investigated by impedance spectroscopy. Three types of dominant conduction were found which depend on the previous thermal treatment of the samples. For untreated samples, at low temperatures (T < 100 °C), electrical conductivity is relatively high (>10{sup −4} S/cm at T ≈ 90 °C) and is dominated by protonic transport within structural water molecules. For thermal annealing in inert atmosphere up to 150 °C, water molecules are released from the nanotube structure resulting in a dehydrated H{sub 2}Ti{sub 3}O{sub 7} phase. Such phase has a low, thermally-dependent, electrical conductivity (10{sup −8} S/cm at T ≈ 90 °C) with activation energy of 0.68 eV. For samples annealed up to 260 °C, loss of OH groups, and consequent generation of oxygen vacancies, occurs that result in the non-stoichiometric H{sub 2(1−z)}Ti{sub 3}O{sub 7−z} phase. This phase has much higher conductivity (10{sup −5} S/cm at T ≈ 90 °C) and lower associated activation energy (0.40 eV). The generation of oxygen vacancies is confirmed by electron paramagnetic resonance measurements at room temperature, which revealed the presence of single-electron-trapped oxygen vacancies. The activation energy value found is consistent with the thermal ionization energy of the oxygen vacancies. Such defect formation represents the initial stage of the phase transformation from titanate to TiO{sub 2} (B). X-ray diffraction and Raman spectroscopy measurements also support such interpretation.

  5. Rough surface electrical contact resistance considering scale dependent properties and quantum effects

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Robert L., E-mail: jackson@auburn.edu [Department of Mechanical Engineering, Auburn University, Auburn, Alabama 36849 (United States); Crandall, Erika R.; Bozack, Michael J. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

    2015-05-21

    The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness.

  6. Structure-dependent optical and electrical transport properties of nanostructured Al-doped ZnO.

    Science.gov (United States)

    Gondoni, P; Ghidelli, M; Di Fonzo, F; Carminati, M; Russo, V; Li Bassi, A; Casari, C S

    2012-09-14

    The structure-property relation of nanostructured Al-doped ZnO thin films has been investigated in detail through a systematic variation of structure and morphology, with particular emphasis on how they affect optical and electrical properties. A variety of structures, ranging from compact polycrystalline films to mesoporous, hierarchically organized cluster assemblies, are grown by pulsed laser deposition at room temperature at different oxygen pressures. We investigate the dependence of functional properties on structure and morphology and show how the correlation between electrical and optical properties can be studied to evaluate energy gap, conduction band effective mass and transport mechanisms. Understanding these properties opens up opportunities for specific applications in photovoltaic devices, where optimized combinations of conductivity, transparency and light scattering are required.

  7. Methylammonium lead iodide grain boundaries exhibit depth-dependent electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, Gordon A.; Yang, Mengjin; Berweger, Samuel; Killgore, Jason P.; Kabos, Pavel; Berry, Joseph J.; Zhu, Kai; DelRio, Frank W.

    2016-01-01

    In this communication, the nanoscale through-film and lateral photo-response and conductivity of large-grained methylammonium lead iodide (MAPbI3) thin films are studied. In perovskite solar cells (PSC), these films result in efficiencies >17%. The grain boundaries (GBs) show high resistance at the top surface of the film, and act as an impediment to photocurrent collection. However, lower resistance pathways between grains exist below the top surface of the film, indicating that there exists a depth-dependent resistance of GBs (RGB(z)). Furthermore, lateral conductivity measurements indicate that RGB(z) exhibits GB-to-GB heterogeneity. These results indicate that increased photocurrent collection along GBs is not a prerequisite for high-efficiency PSCs. Rather, better control of depth-dependent GB electrical properties, and an improvement in the homogeneity of the GB-to-GB electrical properties, must be managed to enable further improvements in PSC efficiency. Finally, these results refute the implicit assumption seen in the literature that the electrical properties of GBs, as measured at the top surface of the perovskite film, necessarily reflect the electrical properties of GBs within the thickness of the film.

  8. Size dependent magnetic and electrical properties of Ba-doped nanocrystalline BiFeO3

    Directory of Open Access Journals (Sweden)

    Mehedi Hasan

    2016-03-01

    Full Text Available Improvement in magnetic and electrical properties of multiferroic BiFeO3 in conjunction with their dependence on particle size is crucial due to its potential applications in multifunctional miniaturized devices. In this investigation, we report a study on particle size dependent structural, magnetic and electrical properties of sol-gel derived Bi0.9Ba0.1FeO3 nanoparticles of different sizes ranging from ∼ 12 to 49 nm. The substitution of Bi by Ba significantly suppresses oxygen vacancies, reduces leakage current density and Fe2+ state. An improvement in both magnetic and electrical properties is observed for 10 % Ba-doped BiFeO3 nanoparticles compared to its undoped counterpart. The saturation magnetization of Bi0.9Ba0.1FeO3 nanoparticles increase with reducing particle size in contrast with a decreasing trend of ferroelectric polarization. Moreover, a first order metamagnetic transition is noticed for ∼ 49 nm Bi0.9Ba0.1FeO3 nanoparticles which disappeared with decreasing particle size. The observed strong size dependent multiferroic properties are attributed to the complex interaction between vacancy induced crystallographic defects, multiple valence states of Fe, uncompensated surface spins, crystallographic distortion and suppression of spiral spin cycloid of BiFeO3.

  9. Thermoelectric Property Dependence and Geometry Optimization of Peltier Current Leads Using Highly Electrically Conductive Thermoelectric Materials

    Science.gov (United States)

    Fujii, Tomohiro; Fukuda, Shinji; Emoto, Masahiko; Osada, Koudai; Kawahara, Toshio; Hamabe, Makoto; Watanabe, Hirofumi; Ivanov, Yury; Sun, Jian; Yamaguchi, Satarou

    2011-05-01

    Thermoelectric materials are promising candidates for use in energy-saving devices in many fields. They are also useful in superconducting applications such as those using Peltier current leads (PCLs) to reduce system heat loss. In the case of PCLs, consideration must be given to Joule heating. Furthermore, the performance of PCLs is intricately dependent on their thermoelectric properties. In addition to the figure of merit Z, consideration of the electrical conductivity is also important for the design of high-performance PCLs. In this paper, we discuss the resistivity dependence of the performance of PCLs using model parameters obtained from real devices.

  10. Temperature dependent dielectric and electric modulus properties of ZnS nano particles

    Science.gov (United States)

    Ali, Hassan; Falak, Attia; Rafiq, M. A.; Khan, Usman; Karim, Shafqat; Nairan, Adeela; Jing, Tang; Sun, Yue; Sun, Sibai; Qian, Chenjiang; Xu, Xiulai

    2017-03-01

    A comprehensive study of the dielectric and electric modulus properties of Zinc Sulfide (ZnS) semiconductor nanoparticles has been conducted using impedance spectroscopy in the frequency range of 200 Hz to 2 MHz and over the temperature range of 300 K to 400 K. Microscopic analysis confirms the formation of spherical nanoparticles with an average size of ∼20 nm. Maxwell–Wagner–Sillars (MWS) interfacial polarization is responsible for the increase in dielectric permittivity and dielectric loss at lower frequencies. Increase in dielectric permittivity and dielectric loss has been observed with a rise in temperature. The electric modulus complex plane plot reveals the presence of the grain (bulk) effect and non-Debye type relaxation processes in the material. The non-Debye type processes have also been confirmed by the asymmetric relaxation peaks of the imaginary part of the electric modulus. The frequency dependent maximum of the imaginary part of the electric modulus follows the Arrhenius law with an activation energy of 0.13 eV. The modulus analysis also establishes that the hopping mechanism is responsible for electrical conduction in the ZnS nanoparticles.

  11. Layer-dependent nanoscale electrical properties of graphene studied by conductive scanning probe microscopy

    Directory of Open Access Journals (Sweden)

    Zhao Shihua

    2011-01-01

    Full Text Available Abstract The nanoscale electrical properties of single-layer graphene (SLG, bilayer graphene (BLG and multilayer graphene (MLG are studied by scanning capacitance microscopy (SCM and electrostatic force microscopy (EFM. The quantum capacitance of graphene deduced from SCM results is found to increase with the layer number (n at the sample bias of 0 V but decreases with n at -3 V. Furthermore, the quantum capacitance increases very rapidly with the gate voltage for SLG, but this increase is much slowed down when n becomes greater. On the other hand, the magnitude of the EFM phase shift with respect to the SiO2 substrate increases with n at the sample bias of +2 V but decreases with n at -2 V. The difference in both quantum capacitance and EFM phase shift is significant between SLG and BLG but becomes much weaker between MLGs with a different n. The layer-dependent quantum capacitance behaviors of graphene could be attributed to their layer-dependent electronic structure as well as the layer-varied dependence on gate voltage, while the layer-dependent EFM phase shift is caused by not only the layer-dependent surface potential but also the layer-dependent capacitance derivation.

  12. Linking the pressure dependency of elastic and electrical properties of porous rocks by a dual porosity model

    Science.gov (United States)

    Han, Tongcheng; Gurevich, Boris; Pervukhina, Marina; Clennell, Michael Ben; Zhang, Junfang

    2016-04-01

    Knowledge about the pressure dependency of elastic and electrical properties is important for a variety of geophysical applications. We present a technique to invert for the stiff and compliant porosity from velocity measurements made as a function of differential pressure on saturated sandstones. A dual porosity concept is used for dry rock compressibility and a squirt model is employed for the pressure and frequency dependent elastic properties of the rocks when saturated. The total porosity obtained from inversion shows satisfactory agreement with experimental results. The electrical cementation factor was determined using the inverted porosity in combination with measured electrical conductivity. It was found that cementation factor increased exponentially with increasing differential pressure during isostatic loading. Elastic compressibility, electrical cementation factor and electrical conductivity of the saturated rocks correlate linearly with compliant porosity, and electrical cementation factor and electrical conductivity exhibit linear correlations with elastic compressibility of the saturated rocks under loading. The results show that the dual porosity concept is sufficient to explain the pressure dependency of elastic, electrical and joint elastic-electrical properties of saturated porous sandstones.

  13. A study of frequency dependent electrical and dielectric properties of NiO nanoparticles

    Science.gov (United States)

    Usha, V.; Kalyanaraman, S.; Vettumperumal, R.; Thangavel, R.

    2017-01-01

    Nickel oxide nanoparticles were synthesized using low cost sol-gel method. The structure of as prepared NiO nanoparticles has been confirmed from X-ray diffraction (XRD), scanning electron microscope with energy dispersive X-ray (SEM and EDX) spectroscopic analysis. The electrical and dielectric properties were characterized by complex impedance spectroscopy as a function of frequency at different temperatures. To study the dielectric behavior of the nanoparticles different plots like Nyquist plot, modulus plot and Bode plot were used. Also the frequency dependent ac conductivity is analyzed and the activation energy is calculated. The dielectric constant and dielectric loss as a function of frequency at various temperatures are also studied.

  14. Time-Dependent Electrical Properties of Human Nail Upon Hydration In Vivo

    OpenAIRE

    2010-01-01

    The objectives of this study were to investigate the effects of hydration and solution ion concentration on the electrical properties of human nail in vivo and compare these in vivo results with those in vitro. In vivo electrical resistance measurements on the nail were conducted with a three-electrode system in phosphate buffered saline of 0.01–0.6 M. The effect of electric current on nail resistance and possible adverse effects were studied under 1.5- and 9-V iontophoresis in vivo. The elec...

  15. Temperature dependant electrical properties of formyl-TIPPCu(II)/p-Si heterojunction diode

    Science.gov (United States)

    Khan, Dil Nawaz; Sayyad, Muhammad Hassan; Wahab, Fazal; Tahir, Muhammad; Yaseen, Muhammad; Munawar, Munawar Ali; Ali, Mukhtar

    2014-05-01

    This paper reports the temperature dependent electrical characterization of formyl-TIPPCu(II)/p-Si heterojunction diode which was fabricated by growing thin films of formyl-TIPPCu(II) on the p-type silicon substrate by thermal sublimation technique. The variation in electrical characteristics of the fabricated devices has been systematically investigated as the function of temperature by using current-voltage (I-V) measurements in the temperature range 299-339 K. The diode parameters like ideality factor, zero bias barrier height and parasitic series resistance have been found to be strongly temperature dependant. The zero bias barrier height increases while ideality factor and series resistance decreases with increasing temperature.

  16. The growth temperatures dependence of optical and electrical properties of InN films

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    InN films grown on sapphire at different substrate temperatures from 550℃ to 700℃ by metalorganic chemical vapor deposition were investigated. The low-temperature GaN nucleation layer with high-temperature annealing (1100℃) was used as a buffer for main InN layer growth. X-ray diffraction and Raman scattering measurements reveal that the quality of InN films can be improved by increasing the growth temperature to 600℃. Further high substrate temperatures may promote the thermal decomposition of InN films and result in poor crystallinity and surface morphology. The photoluminescence and Hall measurements were employed to characterize the optical and electrical properties of InN films,which also indicates strong growth temperature dependence. The InN films grown at temperature of 600℃ show not only a high mobility with low carrier concentration,but also a strong infrared emission band located around 0.7 eV. For a 600 nm thick InN film grown at 600℃,the Hall mobility achieves up to 938 cm2/Vs with electron concen-tration of 3.9×1018 cm-3.

  17. Frequency dependent electrical properties of nano-CdS/Ag junctions

    Science.gov (United States)

    Mohanta, D.; Choudhury, A.

    2005-05-01

    Polymer embedded cadmium sulfide nanoparticles/quantum dots were synthesized by a chemical route using polyvinyl alcohol (lmw) as the desired matrix. In an attempt to measure the electrical properties of nano-CdS/Ag samples, we propose that contribution from surface traps are mainly responsible in determining the I˜ V and C˜ V characteristics in high frequency ranges. To be specific, beyond 1.2 MHz, the carrier injection from the trap centers of the embedded quantum dots is ensured by large current establishment even at negative biasing condition of the junction. The unexpected nonlinear signature of C˜ V response is believed to be due to the fact that while trying to follow very high signal frequency (at least 10-3 of recombination frequency), there is complete abruptness in carrier trapping (charging) or/and detrapping (decay) in a given CdS nanoparticle assembly. The frequency dependent unique role of the trap carriers certainly find application in nanoelectronic devices at a desirable frequency of operation.

  18. Morphology and crystalline-phase-dependent electrical insulating properties in tailored polypropylene for HVDC cables

    Science.gov (United States)

    Zha, Jun-Wei; Yan, Hong-Da; Li, Wei-Kang; Dang, Zhi-Min

    2016-11-01

    Polypropylene (PP) has become one promising material to potentially replace the cross-link polyethylene used for high voltage direct current cables. Besides the isotactic polypropylene, the block polypropylene (b-PP) and random polypropylene (r-PP) can be synthesized through the copolymerization of ethylene and propylene molecules. In this letter, the effect of morphology and crystalline phases on the insulating electrical properties of PP was investigated. It was found that the introduction of polyethylene monomer resulted in the formation of β and γ phases in b-PP and r-PP. The results from the characteristic trap energy levels indicated that the β and γ phases could induce deep electron traps which enable to capture the carriers. And the space charge accumulation was obviously suppressed. Besides, the decreased electrical conductivity was observed in b-PP and r-PP. It is attributed to the existence of deep traps which can effectively reduce the carrier mobility and density in materials.

  19. Electric- and magnetic-field dependence of the electronic and optical properties of phosphorene quantum dots

    Science.gov (United States)

    Li, L. L.; Moldovan, D.; Xu, W.; Peeters, F. M.

    2017-02-01

    Recently, black phosphorus quantum dots were fabricated experimentally. Motivated by these experiments, we theoretically investigate the electronic and optical properties of rectangular phosphorene quantum dots (RPQDs) in the presence of an in-plane electric field and a perpendicular magnetic field. The energy spectra and wave functions of RPQDs are obtained numerically using the tight-binding approach. We find edge states within the band gap of the RPQD which are well separated from the bulk states. In an undoped RPQD and for in-plane polarized light, due to the presence of well-defined edge states, we find three types of optical transitions which are between the bulk states, between the edge and bulk states, and between the edge states. The electric and magnetic fields influence the bulk-to-bulk, edge-to-bulk, and edge-to-edge transitions differently due to the different responses of bulk and edge states to these fields.

  20. RF Magnetron Sputtering Grown Cu2O Film Structural, Morphological, and Electrical Property Dependencies on Substrate Type.

    Science.gov (United States)

    Ahn, Heejin; Um, Youngho

    2015-03-01

    We investigated the structural, morphological, and electrical properties of cuprous oxide (Cu2O) film dependency on substrate type. Thin films grown using RF magnetron sputtering were characterized by scanning electron microscopy, X-ray diffraction (XRD), and Hall effect measurements. Cu2O thin films were deposited onto sapphire (0001), Si (100), and MgO (110) substrates, and showed Cu2O single phase only, which was confirmed by XRD measurement. Relatively larger compressive strain existed in Cu2O film grown on sapphire and Si, while a smaller tensile strain appeared in Cu2O film grown on MgO. Cu2O thin film crystallite sizes showed a linear dependence on strain. Moreover, film carrier concentration and mobility increased with increasing strain, while resistivity decreased with decreasing strain. Cu2O film strain due to induced strain opens the possibility of controlling structural and electrical properties in device applications.

  1. Contribution of potassium conductances to a time-dependent transition in electrical properties of a cockroach motoneuron soma.

    Science.gov (United States)

    Mills, J D; Pitman, R M

    1999-05-01

    Contribution of potassium conductances to a time-dependent transition in electrical properties of a cockroach motoneuron soma. The cell body of the cockroach (Periplaneta americana) fast coxal depressor motoneuron (Df) displays a time-dependent change in excitability. Immediately after dissection, depolarization evokes plateau potentials, but after several hours all-or-none action potentials are evoked. Because K channel blockers have been shown to produce a similar transition in electrical properties, we have used current-clamp, voltage-clamp and action-potential-clamp recording to elucidate the contribution of different classes of K channel to the transition in electrical activity of the neuron. Apamin had no detectable effect on the neuron, but charybdotoxin (ChTX) caused a rapid transition from plateau potentials to spikes in the somatic response of Df to depolarization. In neurons that already produced spikes when depolarized, ChTX increased spike amplitude but did not increase their duration nor decrease the amplitude of their afterhyperpolarization. 4-Aminopyridine (4-AP) (which selectively blocks transient K currents) did not cause a transition from plateau potentials to spikes but did enhance oscillations superimposed on plateau potentials. When applied to neurons that already generated spikes when depolarized, 4-AP could augment spike amplitude, decrease the latency to the first spike, and prolong the afterhyperpolarization. Evidence suggests that the time-dependent transition in electrical properties of this motoneuron soma may result, at least in part, from a fall in calcium-dependent potassium current (IK,Ca), consequent on a gradual reduction in [Ca2+ ]i. Voltage-clamp experiments demonstrated directly that outward K currents in this neuron do fall with a time course that could be significant in the transition of electrical properties. Voltage-clamp experiments also confirmed the ineffectiveness of apamin and showed that ChTX blocked most of IK

  2. Temperature dependence of electrical properties of mixture of exogenous neurotransmitters dopamine and epinephrine

    Science.gov (United States)

    Patki, Mugdha; Patil, Vidya

    2016-05-01

    Neurotransmitters are chemical messengers that support the communication between the neurons. In vitro study of exogenous neurotransmitters Dopamine and Epinephrine and their mixture, carried out to learn about their electrical properties being dielectric constant and conductivity amongst others. Dielectric constant and conductivity of the selected neurotransmitters are found to increase with temperature. As a result, the time constant of the system increases with temperature. This change leads to increase in the time taken by the synapse to transport the action potential. The correlation between physical properties of exogenous neurotransmitters and psychological and physiological behaviour of human being may be understood with the help of current study. The response time of Epinephrine is in microseconds whereas response time of Dopamine is in milliseconds. The response time for both the neurotransmitters and their mixture is found to be increasing with temperature indicating the symptoms such as depression, apathy, chronic fatigue and low physical energy with no desire to exercise the body, which are observed during the fever.

  3. Vibrational-rotational dependence of molecular properties. Electric field gradients for HCl, LiCl, NaCl and KCl

    Science.gov (United States)

    Seth, Michael; Pernpointner, Markus; Bowmaker, Graham A.; Schwerdtfeger, Peter

    The vibrational-rotational dependence of the nuclear quadrupole coupling constant (NQCC) for the isotopes 2H, 7Li, 23Na, 39K, and 35Cl is analysed in detail for the diatomic Group 1 chlorides HCl, LiCl, NaCl and KCl. The potential energy curves were calculated pointwise by using coupled cluster techniques. The electric field gradients (EFGs) and dipole moments were obtained analytically from a QCISD procedure using the Z vector method. Generally the calculated spectroscopic properties are in very good agreement with experimental data. Relativistic effects taken into account by a coupled cluster Douglas-Kroll procedure can safely be neglected for the electric field gradients up to potassium. The Inglis model which explains the trend and magnitudes of EFGs within an ionic model of weakly polarized atoms is analysed. According to this model the derivatives of the EFG, ∂nq (R)/∂Rn , with respect to the internuclear distance R should show alternating sign behaviour with increasing power n. Hence, the mechanical anharmonicity (deviation from Hooke's law potential) and the electrical anharmonicity (curvature of q(R)) are of different sign, and we expect partial cancellation of anharmonicity effects in the vibrational dependence of the NQCCs. Nevertheless, a perturbative vibrational-rotational analysis reveals a strong dependence of the chlorine and Group 1 element NQCCs on the vibrational level due to dominating mechanical anharmonicity.

  4. Size-, electric-field-, and frequency-dependent third-order nonlinear optical properties of hydrogenated silicon nanoclusters

    Science.gov (United States)

    Li, Haipeng; Xu, Hu; Shen, Xiaopeng; Han, Kui; Bi, Zetong; Xu, Runfeng

    2016-06-01

    We investigated the electronic properties and second hyperpolarizabilities of hydrogenated silicon nanoclusters (H-SiNCs) by using the density functional theory method. The effects of cluster size, external electric field and incident frequency on the second hyperpolarizability were also examined, respectively. We found that small H-SiNCs exhibit large second hyperpolarizability. With the increase of the number of silicon atoms in H-SiNCs, the frontier molecular orbital energy gap decreases, attributed to the enhancement of the second hyperpolarizability. Interestingly, we also found the electric-field-induced gigantic enhancement of the second hyperpolarizability for H-SiNCs due to the change of electron density distributions. In addition, our results demonstrate a significant dependence on the frequency of incident light.

  5. Size-, electric-field-, and frequency-dependent third-order nonlinear optical properties of hydrogenated silicon nanoclusters.

    Science.gov (United States)

    Li, Haipeng; Xu, Hu; Shen, Xiaopeng; Han, Kui; Bi, Zetong; Xu, Runfeng

    2016-06-16

    We investigated the electronic properties and second hyperpolarizabilities of hydrogenated silicon nanoclusters (H-SiNCs) by using the density functional theory method. The effects of cluster size, external electric field and incident frequency on the second hyperpolarizability were also examined, respectively. We found that small H-SiNCs exhibit large second hyperpolarizability. With the increase of the number of silicon atoms in H-SiNCs, the frontier molecular orbital energy gap decreases, attributed to the enhancement of the second hyperpolarizability. Interestingly, we also found the electric-field-induced gigantic enhancement of the second hyperpolarizability for H-SiNCs due to the change of electron density distributions. In addition, our results demonstrate a significant dependence on the frequency of incident light.

  6. Size-, electric-field-, and frequency-dependent third-order nonlinear optical properties of hydrogenated silicon nanoclusters

    Science.gov (United States)

    Li, Haipeng; Xu, Hu; Shen, Xiaopeng; Han, Kui; Bi, Zetong; Xu, Runfeng

    2016-01-01

    We investigated the electronic properties and second hyperpolarizabilities of hydrogenated silicon nanoclusters (H-SiNCs) by using the density functional theory method. The effects of cluster size, external electric field and incident frequency on the second hyperpolarizability were also examined, respectively. We found that small H-SiNCs exhibit large second hyperpolarizability. With the increase of the number of silicon atoms in H-SiNCs, the frontier molecular orbital energy gap decreases, attributed to the enhancement of the second hyperpolarizability. Interestingly, we also found the electric-field-induced gigantic enhancement of the second hyperpolarizability for H-SiNCs due to the change of electron density distributions. In addition, our results demonstrate a significant dependence on the frequency of incident light. PMID:27305957

  7. Temperature and frequency dependent dielectric properties of electrically conducting oxidatively synthesized polyazomethines and their structural, optical, and thermal characterizations

    Science.gov (United States)

    Dineshkumar, Sengottuvelu; Muthusamy, Athianna; Chandrasekaran, J.

    2017-01-01

    Three azomethine diol monomers were synthesized by condensing with methanolic solution of aromatic aldehydes with ethylenediamine. These monomers were oxidatively polymerized using NaOCl as an oxidant. The structures of the monomers and polymers were confirmed by various spectroscopic techniques. Spectral results showed that the repeating units are linked by Csbnd C and Csbnd Osbnd C couplings. The polyazomethines have fluorescent property with high stokes shift. Solid state electrical conductivity of polymers both in I2 doped and undoped states, temperature and frequency dependent dielectric measurements were made by two probe method. The electrical conductivities of polyazomethines were compared based on the charge densities on imine nitrogens obtained from Huckel calculation. The conductivity of polymers increases with increase in iodine vapour contact time. Among the synthesized polymers PHNAE has shown high dielectric constant at low applied frequency of 50 Hz at 393 K due the presence of bulky naphthalene unit in polymer chain.

  8. Issledovanie temperaturnoi i chastotnoi zavisimostei elektrofizicheskikh svoistv dioksida tseriya [Investigation of the temperature and frequency dependences of the electrical properties of cerium dioxide

    Directory of Open Access Journals (Sweden)

    V. A. Ogorodnik

    1993-05-01

    Full Text Available An experimental study of the electrical properties of CeO2 - temperature and frequency dependences of the conductivity, permittivity and dielectric loss tangent, as well as an interpretation of the results obtained

  9. Surface electrical properties experiment

    Science.gov (United States)

    Simmons, Gene; Strangway, David; Annan, Peter; Baker, Richard G.; Bannister, Lawrence; Brown, Raymon; Cooper, William; Cubley, Dean; deBettencourt, Joseph; England, Anthony W.; Groener, John; Kong, Jin-Au; LaTorraca, Gerald; Meyer, James; Nanda, Ved; Redman, David; Rossiter, James; Tsang, Leung; Urner, Joseph; Watts, Raymond

    1973-01-01

    The surface electrical properties (SEP) experiment was used to explore the subsurface material of the Apollo 17 landing site by means of electromagnetic radiation. The experiment was designed to detect electrical layering, discrete scattering bodies, and the possible presence of water. From the analysis of the data, it was expected that values of the electrical properties (dielectric constant and loss tangent) of lunar material in situ would be obtained.

  10. Frequency and Temperature Dependences of Dielectric Dispersion and Electrical Properties of Polyvinylidene Fluoride/Expanded Graphite Composites

    National Research Council Canada - National Science Library

    Li, Yu Chao; Li, Robert Kwok Yiu; Tjong, Sie Chin

    2010-01-01

    ...) by direct melt blending process. The electrical conductivity and dielectric properties of resulting PVDF/EG composites were investigated in a wide range of frequencies from [superscript]102[/superscript] to [superscript]108[/superscript] Hz...

  11. Temperature dependence of spectroscopic and electrical properties of Cr(Fe):ZnSe laser active materials

    Science.gov (United States)

    Gafarov, Ozarfar; Watkins, Rick; Bernard, Chandler; Fedorov, Vladimir; Mirov, Sergey

    2017-02-01

    Temperature influence on spectroscopic characteristics is crucial for many aspects of laser engineering including output noise, single frequency oscillation, and thermal bistability. We report on the spectroscopic characterization of chromium and iron doped ZnSe gain element media at temperatures ranging from 77K to 389K. Heating of Cr:ZnSe resulted in the absorption peak shifting to a shorter wavelength from 1.806 μm at 77K to 1.753 μm at 389K. It also resulted in broadening of the absorption band from Δλ=260 cm-1nm to Δλ=373 cm-1nm and decreasing of the absorption cross section by 69%. Similar characterization was done for Fe:ZnSe laser material. The cooling of the Fe:ZnSe crystal from room temperature to 77K resulted in a 32% increase of the absorption coefficient at 2.94 μm which is usually used as a pump source. We also studied the absorption of the electrical free-carriers in n-type Al:ZnSe crystals in visible and mid- IR absorption spectral ranges. Diffusion of Al into ZnSe samples was achieved by annealing at 1000°C during 4 days in Al vapors. It was demonstrated that free-carriers absorption of Al:ZnSe samples with resistivity σ=100-150 Ω×cm resulted in an increase of the absorption coefficient at 2.4 μm up to 2.5 cm-1.

  12. Thickness dependence of electrical properties of PZT films deposited on metal substrates by laser-assisted aerosol deposition.

    Science.gov (United States)

    Baba, S; Tsuda, H; Akedo, J

    2008-05-01

    Dependence of electrical properties-dielectric, ferroelectric, and piezoelectric properties-on film thickness was studied for lead-zirconate titanate (PZT) thick films directly deposited onto stainless-steel (SUS) substrates in actuator devices by using a carbon dioxide (CO(2) ), laser assisted aerosol deposition technique. Optical spectroscopic analysis data and laser irradiation experiments revealed that absorption at a given wavelength by the film increased with increasing film thickness. Dielectric constant epsilon, remanent polarization value P(r), and coercive field strength E(c) of PZT films directly deposited onto a SUS-based piezoelectric actuator substrate annealed by CO(2) laser irradiation at 850 degrees C improved with increasing film thickness, and for films thicker than 25 microm, epsilon 800, P(r) 40 microC/cm(2), and E(c) 45 kV/cm. In contrast, the displacement of the SUS-based actuator with the laser-annealed PZT thick film decreased with increasing film thickness.

  13. Electrical Properties of Natural Pyroxenite

    Institute of Scientific and Technical Information of China (English)

    YI Li; WANG Duo-Jun; LI He-Ping

    2005-01-01

    @@ The complex electrical properties of natural pyroxenite were measured over a frequency range from 0.01 to 106 Hz, at 3.0GPa and 1266-1504K, using the solid buffers (Mo-MoO2) to control the oxygen fugacity. Thefrequency dependence of electrical properties for the natural pyroxenite is investigated. Two distinct conduction mechanisms of the natural pyroxenite are observed: grain interior and grain boundary conduction. Grain interior transport controls the response above 100 Hz, whereas grain boundary transport dominates between ~ 100 and 0.01 Hz. Electrical response of natural pyroxenite is modelled with an equivalent circuit in which parallel RC circuit elements representing grain interior and grain boundary responses act in series. The grain boundaries do not enhance the total conductivity of natural pryoxenite. The total electrical conductivity of natural pyroxenite is lower than either grain interior or grain boundary conductivity alone.

  14. Electric-Field Effect on the Angle-Dependent Magnetotransport Properties of Quasi-One-Dimensional Conductors

    Science.gov (United States)

    Kobayashi, K.; Saito, M.; Ohmichi, E.; Osada, T.

    2006-03-01

    We report a novel electric field effect on angular dependent magnetotransport in quasi-one-dimensional layered conductors with a pair of sheetlike Fermi surfaces. Under tilted magnetic fields and additional interlayer electric fields, semiclassical electron orbits on two Fermi sheets become periodic at different magnetic field orientations. This causes double splitting of the Lebed’s commensurability resonance in interlayer transport, and the amount of splitting allows us to estimate the Fermi velocity directly. We have successfully demonstrated this effect in the organic conductor α-(BEDT-TTF)2KHg(SCN)4.

  15. Frequency Dependent Electrical Properties of Ferroelectric Ba0.8Sr0.2TiO3 Thin Film

    Directory of Open Access Journals (Sweden)

    Ala’eddin A. SAIF

    2011-07-01

    Full Text Available The frequency dependent electrical parameters, such as impedance, electric modulus, dielectric constant and AC conductivity for ferroelectric Ba0.8Sr0.2TiO3 thin film have been investigated within the range of 1 Hz and 106 Hz at room temperature. Z* plane shows two regions corresponding to the bulk mechanism and the distribution of the grain boundaries-electrodes process. M" versus frequency plot reveals a relaxation peak, which is not observed in the ε″ plot and it has been found that this peak is a non-Debye-type. The frequency dependent conductivity plot shows three regions of conduction processes, i. e., a low-frequency region due to DC conduction, a mid-frequency region due to translational hopping motions and a high-frequency region due to localized hopping and/or reorientational motion.http://dx.doi.org/10.5755/j01.ms.17.2.490

  16. Electrical properties of materials

    CERN Document Server

    Solymar, L; Syms, R R A

    2014-01-01

    An informal and highly accessible writing style, a simple treatment of mathematics, and clear guide to applications have made this book a classic text in electrical and electronic engineering. Students will find it both readable and comprehensive. The fundamental ideas relevant to the understanding of the electrical properties of materials are emphasized; in addition, topics are selected in order to explain the operation of devices having applications (or possible future applications) in engineering. The mathematics, kept deliberately to a minimum, is well within the grasp of a second-year student. This is achieved by choosing the simplest model that can display the essential properties of a phenomenom, and then examining the difference between the ideal and the actual behaviour. The whole text is designed as an undergraduate course. However most individual sections are self contained and can be used as background reading in graduate courses, and for interested persons who want to explore advances in microele...

  17. Electrical properties of flexible multi-channel Si nanowire field-effect transistors depending on the number of Si nanowires.

    Science.gov (United States)

    Kim, Do Hoon; Lee, Su Jeong; Lee, Sang Hoon; Myoung, Jae-Min

    2016-05-25

    Flexible multi-channel Si nanowire (NW) field-effect transistors (FETs) were investigated to determine the effect of the number of Si NWs. The Langmuir-Blodgett method was applied for the formation of well-aligned Si NW monolayers, and an ion-gel with a high dielectric constant was used as a gate insulator in a top-gate TFT structure to secure flexibility. Like typical nanoelectronic devices, the drain current changed with the number of Si NWs. However, unlike previous reports, the mobility of the multi-channel Si NW FETs increased from 42.8 to 124.6 cm(2) V(-1) s(-1) as the number of Si NWs was increased from 1 to 58. To verify the feasibility of our approach, the electrical performance of the TFTs fabricated on a flexible polyimide (PI) substrate was analyzed in respect of the bending strain (0.08-1.51%) and bending cycle (up to 12 000 cycles). As the number of Si NWs was increased, the trade-off between electrical and mechanical properties during bending tests was confirmed, and the appropriate number of Si NWs was optimized for a flexible FET with excellent performance.

  18. Using multivariate geostatistics to assess patterns of spatial dependence of apparent soil electrical conductivity and selected soil properties.

    Science.gov (United States)

    Siqueira, Glécio Machado; Dafonte, Jorge Dafonte; Valcárcel Armesto, Montserrat; França e Silva, Ênio Farias

    2014-01-01

    The apparent soil electrical conductivity (ECa) was continuously recorded in three successive dates using electromagnetic induction in horizontal (ECa-H) and vertical (ECa-V) dipole modes at a 6 ha plot located in Northwestern Spain. One of the ECa data sets was used to devise an optimized sampling scheme consisting of 40 points. Soil was sampled at the 0.0-0.3 m depth, in these 40 points, and analyzed for sand, silt, and clay content; gravimetric water content; and electrical conductivity of saturated soil paste. Coefficients of correlation between ECa and gravimetric soil water content (0.685 for ECa-V and 0.649 for ECa-H) were higher than those between ECa and clay content (ranging from 0.197 to 0.495, when different ECa recording dates were taken into account). Ordinary and universal kriging have been used to assess the patterns of spatial variability of the ECa data sets recorded at successive dates and the analyzed soil properties. Ordinary and universal cokriging methods have improved the estimation of gravimetric soil water content using the data of ECa as secondary variable with respect to the use of ordinary kriging.

  19. Electrical properties of bone. A review.

    Science.gov (United States)

    Singh, S; Saha, S

    1984-06-01

    A review of the available data on the electrical properties (resistance, capacitance, dielectric constant, dielectric loss factor, and dissipation factor, etc.) of whole as well as standardized bone specimens suggest that impedance was lowest in the longitudinal direction and highest in the radial direction. This is further evidence of the anisotropic nature of bone. The electrical properties of fully hydrated bone were significantly different from those of dry and partially wet bone and these properties were highly frequency-dependent. Other variables that influence the electrical properties, such as moisture content, principles and methods of measurement, temperature, and pH and conductivity of the immersing fluid, etc., have also been reviewed. Delineation of these variables is important in reporting test results on the electrical properties of bone; only then can the data on different electrical properties of bone reported by various authors be compared. Future research is needed to characterize the effect of age, microstructure, mineral content, and various disease processes on the electrical properties of bone. Such information may lead to new insight on the role of electrical properties on bone remodeling. An understanding of the electrical behavior of bone is also important for the design of electrical stimulation devices and their proper use for maximum osteogenic effect.

  20. Substrate dependent structural, optical and electrical properties of ZnS thin films grown by RF sputtering

    Science.gov (United States)

    Pathak, Trilok K.; Kumar, Vinod; Purohit, L. P.; Swart, H. C.; Kroon, R. E.

    2016-10-01

    Zinc sulphide (ZnS) films are of great importance for applications in various optoelectronic devices. ZnS thin films were grown on glass, indium tin oxide (ITO) and Corning glass substrates by radio-frequency magnetron sputtering at a temperature of 373 K and a comparative study of the structural, optical and electrical properties was performed using X-ray diffraction (XRD), scanning electron microscopy, optical and current-voltage (I-V) measurements. The XRD patterns showed that the sputtered thin films exhibited good crystallinity with the (111) peak around 2θ=28.3° indicating preferential orientation of the cubic structure. The maximum strain and most densely packed grains were obtained for the Corning glass substrate. The transmittance spectra of the films were measured in the wavelength range from 200 to 800 nm, showing that the films are about 77% transparent in the visible region. A slight change of 3.50 eV to 3.54 eV was found for the bandgap of the films deposited on different substrates. The ZnS thin films deposited on Corning glass show better crystallinity, morphology and I-V characteristics than that deposited on ordinary glass and ITO substrates.

  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. Frequency and voltage dependence dielectric properties, ac electrical conductivity and electric modulus profiles in Al/Co3O4-PVA/p-Si structures

    Science.gov (United States)

    Bilkan, Çiğdem; Azizian-Kalandaragh, Yashar; Altındal, Şemsettin; Shokrani-Havigh, Roya

    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 (σac) values of Al/Co3O4-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 σdc and σac, 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 Nss effects with increasing frequency.

  3. HfO{sub 2} dielectric thickness dependence of electrical properties in graphene field effect transistors with double conductance minima

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Cheng; Xie, Dan, E-mail: xiedan@mail.tsinghua.edu.cn; Xu, Jian-Long; Sun, Yi-Lin; Dai, Rui-Xuan; Li, Xian [Institute of Microelectronics, Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084 (China); Li, Xin-Ming [National Center for Nanoscience and Technology, Zhongguancun, Beijing 100190 (China); Zhu, Hong-Wei [School of Materials Science and Engineering, State Key Laboratory of New Ceramics and Fine Processing, Key Laboratory of Materials Processing Technology of MOE, Tsinghua University, Beijing 100084 (China); Center for Nano and Micro Mechanics, Tsinghua University, Beijing 100084 (China)

    2015-10-14

    We investigate the electrical properties in back-gated graphene field effect transistors (GFETs) with SiO{sub 2} dielectric and different thickness of high-k HfO{sub 2} dielectric. The results show that transform characteristic (I{sub ds}–V{sub gs}) curves of GFETs are uniquely W-shaped with two charge neutrality point (left and right) in both SiO{sub 2} and HfO{sub 2} dielectric (SiO{sub 2}-GFETs and HfO{sub 2}-GFETs). The gate voltage reduces drastically in HfO{sub 2}-GFETs compared with that in SiO{sub 2}-GFETs, and it becomes much smaller with the decline of HfO{sub 2} thickness. The left charge neutrality point in I{sub d}–V{sub g} curves of all HfO{sub 2}-GFETs is negative, compared to the positive ones in SiO{sub 2}-GFETs, which means that there exists n-doping in graphene with HfO{sub 2} as bottom dielectric. We speculate that this n-doping comes from the HfO{sub 2} layer, which brings fixed charged impurities in close proximity to graphene. The carrier mobility is also researched, demonstrating a decreasing trend of hole mobility in HfO{sub 2}-GFETs contrast to that in SiO{sub 2}-GFETs. In a series of HfO{sub 2}-GFETs with different HfO{sub 2} dielectric thickness, the hole mobility shows a tendency of rise when the thickness decreases to 7 nm. The possible reason might be due to the introduced impurities into HfO{sub 2} film from atomic layer deposition process, the concentration of which varies from the thickness of HfO{sub 2} layer.

  4. Dependence of electrical transport properties of CaO(CaMnO3)m (m = 1, 2, 3, ∞) thermoelectric oxides on lattice periodicity

    Science.gov (United States)

    Baranovskiy, Andrei; Amouyal, Yaron

    2017-02-01

    The electrical transport properties of CaO(CaMnO3)m (m = 1, 2, 3, ∞) compounds are studied applying the density functional theory (DFT) in terms of band structure at the vicinity of the Fermi level (EF). It is shown that the total density of states (DOS) values at EF increase with increase in the m-values, which implies an increase in the electrical conductivity, σ, with increasing m-values, in full accordance with experimental results. Additionally, the calculated values of the relative slopes of the DOS at EF correlate with the experimentally measured Seebeck coefficients. The electrical conductivity and Seebeck coefficients were calculated in the framework of the Boltzmann transport theory applying the constant relaxation time approximation. By the analysis of experimental and calculated σ(Τ) dependences, the electronic relaxation time and mean free path values were estimated. It is shown that the electrical transport is dominated by electron scattering on the boundaries between perovskite (CaMnO3) and Ca oxide (CaO) layers inside the crystal lattice.

  5. Temperature-dependent electrical and photo-sensing properties of horizontally-oriented carbon nanotube networks synthesized by sandwich-growth microwave plasma chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Teng, I-Ju [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Hsu, Hui-Lin [Department of Electrical and Computer Engineering, University of Toronto, Toronto M5S 3G4 (Canada); Jian, Sheng-Rui, E-mail: srjian@gmail.com [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 84041, Taiwan (China); Wang, Li-Chun; Chen, Kai-Ling [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Kuo, Cheng-Tzu, E-mail: kurt.kuotw@gmail.com [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Pan, Fu-Ming [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Wang, Wei-Hsiang [Teraxtal Technology Corporation, Hsinchu 30075, Taiwan (China); Juang, Jenh-Yih [Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China)

    2013-02-01

    The electrical and photo-sensing properties of horizontally-oriented interconnected carbon nanotube networks (CNT-NWs) prepared by means of a microwave plasma chemical vapor deposition sandwich-growth process are investigated. The temperature-dependent dark and illuminated current–voltage and transfer characteristics of CNT-NW-assisted devices are measured. Results show that the current–voltage characteristics of the devices exhibit nonlinear behavior, and the current can be further modulated by a gate voltage, revealing p-type semiconducting behavior with a device mobility of ∼ 14.5 cm{sup 2}/V·s and an on-off current ratio of ∼ 10{sup 3}. Moreover, when the CNT-NW-assisted devices are irradiated with 1.25–25 μm infrared (IR) from 300 to 11 K, the photo currents increase approximately 1.1- to 2.7-fold compared to the dark currents at ± 2 V bias voltage. Such results demonstrate that the presented CNT-NWs have high potential for IR photo-sensor applications. - Highlights: ► Horizontally-oriented interconnected carbon nanotube networks (CNT-NWs) were grown. ► A microwave plasma chemical vapor deposition sandwich-growth process was employed. ► Temperature-dependent electrical and photo-sensing properties were investigated. ► Devices based on CNT-NWs exhibit promising transistor characteristics. ► CNT-NWs are capable to detect light in the infrared wavelength range.

  6. Nanoparticle transport effect on magnetohydrodynamic mixed convection of electrically conductive nanofluids in micro-annuli with temperature-dependent thermophysical properties

    Science.gov (United States)

    Malvandi, A.; Moshizi, S. A.; Ganji, D. D.

    2017-04-01

    This is a numerical investigation of nanoparticle transport effect on magnetohydrodynamic mixed convective heat transfer of electrically conductive nanofluids in micro-annuli with temperature-dependent thermophysical properties. The modified Buongiorno's non-homogeneous model is applied for the nanoparticle-fluid suspension to simulate the migration of nanoparticles into the base fluid, originating from the thermophoresis (nanoparticle migration because of temperature gradient) and Brownian motion (nanoparticle slip velocity because of concentration gradient). Due to surface roughness at the solid-fluid interface in micro-annuli, the wall surfaces are subjected to a linear slip condition to assess the non-equilibrium region near the interface. The fluid flow has been assumed to be fully developed, and the governing equations including continuity, momentum, energy, and nanoparticle transport equation are reduced to a system of ordinary differential equations, before they have been solved numerically. The results are presented with and without considering the dependency of thermophysical properties upon the temperature. It is indicated that ignoring the temperature dependency of thermophysical properties does not significantly affect the flow fields and heat transfer behavior of nanofluids, but it changes the relative magnitudes. Furthermore, in the presence of magnetic field, smaller nanoparticles are more appropriate than larger ones.

  7. Thickness-dependent magnetic and electrical transport properties of epitaxial La0.7Sr0.3CoO3 films

    Directory of Open Access Journals (Sweden)

    Binzhi Li

    2017-04-01

    Full Text Available The thickness-dependent magnetic and electrical transport properties of nearly strain-free La0.7Sr0.3CoO3 (LSCO films grown on (001-oriented (LaAlO30.3 (Sr2AlTaO60.7 substrates were systematically studied. A crossover from ferromagnetic/metallic to non-magnetic/insulating behavior occurs at a critical thickness (∼8 nm that is significantly smaller than LSCO films under larger strains in reported literature. X-ray absorption measurements revealed that the difference of functional properties at reduced film thicknesses was accompanied by changes in the valence state of Co ions at the film/substrate interface.

  8. Frequency-Dependent Electrical Transport Properties of 4,4′,4″-Tri(N-carbazolyl)-Triphenylamine Investigated by Impedance Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    LI Bi-Xin; CHEN Jiang-Shan; ZHAO Yong-Biao; MA Dong-Ge

    2011-01-01

    Frequency-dependent electrical transport properties of 4, 4′, 4″-tri (N-carbazolyl)-triphenylamine (TCTA ) are analyzed by impedance spectroscopy (IS) as functions of bias and temperature. The Cole-Cole plot shows a single semicircle which indicates that the equivalent circuit can be designed as a single parallel resistor Rp and capacitor Cp network with a series resistance Rs. The bulk capacitance Cp remains unchanged while the resistance Rp decreases along with bias voltage. Conduction mechanism matches well with the space-charge-limited current (SCLC) model with exponential trap charge distributions. The temperature-dependent impedance studies reveal the activation energy of 0.246eV with no phase change in the temperature range 220-320K. These results indicate that the IS method is applicable for organic semiconductors having a wide band gap.%@@ Frequency-dependent electrical transport properties of 4,4′,4″-tri(N-carbazolyl)-triphenylamine(TCTA ) are analyzed by impedance spectroscopy(IS) as functions of bias and temperature.The Cole-Cole plot shows a single semicircle which indicates that the equivalent circuit can be designed as a single parallel resistor Rp and capacitor Cp network with a series resistance Rs.The bulk capacitance Cp remains unchanged while the resistance Rp decreases along with bias voltage.Conduction mechanism matches well with the space-charge-limited current (SCLC) model with exponential trap charge distributions.The temperature-dependent impedance studies reveal the activation energy of 0.246eV with no phase change in the temperature range 220-320K.These results indicate that the IS method is applicable for organic semiconductors having a wide band gap.

  9. Modeling skull electrical properties

    OpenAIRE

    Sadleir, R. J.; A Argibay

    2007-01-01

    Accurate representations and measurements of skull electrical conductivity are essential in developing appropriate forward models for applications such as inverse EEG or Electrical Impedance Tomography of the head. Because of its layered structure, it is often assumed that skull is anisotropic, with an anisotropy ratio around 10. However, no detailed investigation of skull anisotropy has been performed. In this paper we investigate four-electrode measurements of conductivities and their relat...

  10. The electric field distribution in the brain during TTFields therapy and its dependence on tissue dielectric properties and anatomy: a computational study

    Science.gov (United States)

    Wenger, Cornelia; Salvador, Ricardo; Basser, Peter J.; Miranda, Pedro C.

    2015-09-01

    Tumor treating fields (TTFields) are a non-invasive, anti-mitotic and approved treatment for recurrent glioblastoma multiforme (GBM) patients. In vitro studies have shown that inhibition of cell division in glioma is achieved when the applied alternating electric field has a frequency in the range of 200 kHz and an amplitude of 1-3 V cm-1. Our aim is to calculate the electric field distribution in the brain during TTFields therapy and to investigate the dependence of these predictions on the heterogeneous, anisotropic dielectric properties used in the computational model. A realistic head model was developed by segmenting MR images and by incorporating anisotropic conductivity values for the brain tissues. The finite element method (FEM) was used to solve for the electric potential within a volume mesh that consisted of the head tissues, a virtual lesion with an active tumour shell surrounding a necrotic core, and the transducer arrays. The induced electric field distribution is highly non-uniform. Average field strength values are slightly higher in the tumour when incorporating anisotropy, by about 10% or less. A sensitivity analysis with respect to the conductivity and permittivity of head tissues shows a variation in field strength of less than 42% in brain parenchyma and in the tumour, for values within the ranges reported in the literature. Comparing results to a previously developed head model suggests significant inter-subject variability. This modelling study predicts that during treatment with TTFields the electric field in the tumour exceeds 1 V cm-1, independent of modelling assumptions. In the future, computational models may be useful to optimize delivery of TTFields.

  11. Thickness dependence of the structural and electrical properties of ZnO thermal-evaporated thin films

    Indian Academy of Sciences (India)

    A Ghaderi; S M Elahi; S Solaymani; M Naseri; M Ahmadirad; S Bahrami; A E Khalili

    2011-12-01

    ZnO thin films of different thicknesses were prepared by thermal evaporation on glass substrates at room temperature. Deposition process was carried out in a vapour pressure of about 5.54 × 10-5 mbar. The substrate–target distance was kept constant during the process. By XRD and AFM techniques the microstructural characteristics and their changes with variation in thickness were studied. Electrical resistivity and conductivity of samples vs. temperature were investigated by four-probe method. It was shown that an increase in thickness causes a decrease in activation energy.

  12. Temperature dependence on the electrical properties of Ba(Ti{sub 0.90}Zr{sub 0.10})O{sub 3}:2V ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Moura, F. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil); Simoes, A.Z., E-mail: alezipo@yahoo.com [Universidade Federal de Itajuba-Unifei - Campus Itabira, Rua Sao Paulo 377, Bairro: Amazonas, CEP 35900-37, Itabira, MG (Brazil); Paskocimas, C.A.; Zaghete, M.A.; Varela, J.A.; Longo, E. [Laboratorio Interdisciplinar em Ceramica (LIEC), Departamento de Fisico-Quimica, Instituto de Quimica, UNESP, CEP 14800-900, Araraquara, SP (Brazil)

    2010-10-01

    Barium zirconium titanate ferroelectric ceramics modified with vanadium Ba(Ti{sub 0.90}Zr{sub 0.10}V{sub 0.02})O{sub 3} (BZT:2V) were prepared from powders synthesized using the mixed oxide method. The effect of temperature on the structural and electrical properties of BZT:2V ceramics was investigated. X-ray diffraction data evidenced no secondary phases. As temperature decreases, the maximum dielectric permittivity decreased. The fine-grained sample showed a 'relaxor-like' ferroelectric behavior. The dielectric permittivity reaches a maximum value ({epsilon}{sub m} {approx} 16,000 at 1 kHz) for the BZT:2V ceramics sintered at 1623 K for 4 h. Remnant polarization (P{sub r}) and coercive field were also temperature dependent.

  13. Dependence of electrical property on the applied magnetic fields in spin coated Fe(III)-Phorphyrin films

    Science.gov (United States)

    Utari; Kusumandari; Purnama, B.; Mudasir; Abraha, K.

    2016-11-01

    We report here on the experimental results of the effect of external magnetic field on the current flow in plane surface of Fe(III)-porphyrin thin layer. The deposition of the Fe(III)- porphyrin thin layer was done by spin coating method. The I-V characteristics of film were measured by means of two point probes. The sample of layer number N = 4 was used to evaluate the magnetic effect on the electrical currents. The ohmic characteristics of the I-V film measurement were obtained. The current decreases when magnetic field is applied to the system and saturated current is obtained at a given magnetic field. Here, the decrease in the current can be attributed to the recombination of carrier charge under the magnetic field. In addition, the magnitude of the saturated current is found to increase with the increase in the voltage used.

  14. Modeling skull electrical properties.

    Science.gov (United States)

    Sadleir, R J; Argibay, A

    2007-10-01

    Accurate representations and measurements of skull electrical conductivity are essential in developing appropriate forward models for applications such as inverse EEG or Electrical Impedance Tomography of the head. Because of its layered structure, it is often assumed that skull is anisotropic, with an anisotropy ratio around 10. However, no detailed investigation of skull anisotropy has been performed. In this paper we investigate four-electrode measurements of conductivities and their relation to tissue anisotropy ratio (ratio of tangential to radial conductivity) in layered or anisotropic biological samples similar to bone. It is shown here that typical values for the thicknesses and radial conductivities of individual skull layers produce tissue with much smaller anisotropy ratios than 10. Moreover, we show that there are very significant differences between the field patterns formed in a three-layered isotropic structure plausible for bone, and those formed assuming that bone is homogeneous and anisotropic. We performed a measurement of conductivity using an electrode configuration sensitive to the distinction between three-layered and homogeneous anisotropic composition and found results consistent with the sample being three-layered. We recommend that the skull be more appropriately represented as three isotropic layers than as homogeneous and anisotropic.

  15. Temperature-Dependent Electrical Properties and Carrier Transport Mechanisms of TMAH-Treated Ni/Au/Al2O3/GaN MIS Diode

    Science.gov (United States)

    Reddy, M. Siva Pratap; Puneetha, Peddathimula; Reddy, V. Rajagopal; Lee, Jung-Hee; Jeong, Seong-Hoon; Park, Chinho

    2016-11-01

    The temperature-dependent electrical properties and carrier transport mechanisms of tetramethylammonium hydroxide (TMAH)-treated Ni/Au/Al2O3/GaN metal-insulator-semiconductor (MIS) diodes have been investigated by current-voltage ( I- V) and capacitance-voltage ( C- V) measurements. The experimental results reveal that the barrier height ( I- V) increases whereas the ideality factor decreases with increasing temperature. The TMAH-treated Ni/Au/Al2O3/GaN MIS diode showed nonideal behaviors which indicate the presence of a nonuniform distribution of interface states ( N SS) and effect of series resistance ( R S). The obtained R S and N SS were found to decrease with increasing temperature. Furthermore, it was found that different transport mechanisms dominated in the TMAH-treated Ni/Au/Al2O3/GaN MIS diode. At 150 K to 250 K, Poole-Frenkel emission (PFE) was found to be responsible for the reverse leakage, while Schottky emission (SE) was the dominant mechanism at high electric fields in the temperature range from 300 K to 400 K. Feasible energy band diagrams and possible carrier transport mechanisms for the TMAH-treated Ni/Au/Al2O3/GaN MIS diode are discussed based on PFE and SE.

  16. Modeling the interaction of electric current and tissue: importance of accounting for time varying electric properties.

    Science.gov (United States)

    Evans, Daniel J; Manwaring, Mark L

    2007-01-01

    Time varying computer models of the interaction of electric current and tissue are very valuable in helping to understand the complexity of the human body and biological tissue. The electrical properties of tissue, permittivity and conductivity, are vital to accurately modeling the interaction of the human tissue with electric current. Past models have represented the electric properties of the tissue as constant or temperature dependent. This paper presents time dependent electric properties that change as a result of tissue damage, temperature, blood flow, blood vessels, and tissue property. Six models are compared to emphasize the importance of accounting for these different tissue properties in the computer model. In particular, incorporating the time varying nature of the electric properties of human tissue into the model leads to a significant increase in tissue damage. An important feature of the model is the feedback loop created between the electric properties, tissue damage, and temperature.

  17. Behavior of temperature dependent electrical properties of Pd/Au Schottky contact to GaN grown on Si substrate by MBE

    Science.gov (United States)

    Singh Nirwal, Varun; Rao Peta, Koteswara

    2016-12-01

    We investigated the effect of temperature on the behavior of electrical properties of Pd/Au Schottky contact to GaN/Si (111) in the temperature range of 125-325 K in steps of 25 K using current-voltage (I-V) and capacitance-voltage (C-V) analysis. The Schottky barrier height (ϕ I-V ) and ideality factor is calculated using standard thermionic emission theory. The value of ϕ I-V was found to increase from 0.41 ± 0.002 eV to 0.79 ± 0.008 eV when temperature varied from 125 to 325 K. The ideality factor of diodes also decreased from 5.91 ± 0.01 to 1.03 ± 0.05 with increase in temperature. The series resistance (R s) is calculated using Cheung’s method and it is observed that the value of R s decreased from 74.40 ± 0.32 Ω to 58.59 ± 0.11 Ω when the temperature increased from 125 to 325 K. Barrier height (ϕ C-V ) and effective carrier concentration (Nd ) is also reported from C-V characteristics as a function of temperature and the value of ϕ C-V was found to decrease with increase in temperature. The behavior of barrier heights obtained from I-V and C-V characteristics is different due to difference in the nature of measurement techniques. The deviation of conventional Richardson’s constant from theoretical value of GaN is due to unusual behavior of temperature dependent electrical properties and barrier inhomogeneity. This is successfully explained by assuming the double Gaussian distribution of inhomogeneous barrier heights of Au/Pd/GaN/Si Schottky diode.

  18. Frequency and temperature dependence of dielectric and electric properties of Ba2-xSm4+2x/3Ti8O24 with structural analysis

    Directory of Open Access Journals (Sweden)

    Narang Sukhleen Bindra

    2015-06-01

    Full Text Available Dielectric ceramics samples of barium titanium oxide doped with samarium, having a complex structural formula of Ba2-xSm4+2x/3Ti8O24 (referred to as BST, were fabricated by a high temperature solid-state reaction technique with varying x (0.0, 0.2, 0.4, 0.6. X-ray diffraction technique was used to check the formation of particular phases. Scanning electron microscope technique was used to study the surface morphology of the samples. The samples were studied in a temperature range of 298 K to 623 K and frequency range of 10 KHz to 1 MHz. The dielectric constant (εr, loss tangent (tan δ, and AC conductivity (σAC were measured on sintered disks of BST samples. The DC resistivity of different compositions was measured at room temperature. Detailed studies of dielectric and electrical properties showed that these properties are strongly dependent on composition, frequency and temperature. The compounds showed stable behavior in lower temperature range (up to 523 K, therefore, they can be used in practical applications in this temperature range.

  19. Thickness-dependent Electrical and Piezoelectric Properties of Lead-Free Ferroelectric Ba0.8Sr0.2TiO3 Thin Films

    Directory of Open Access Journals (Sweden)

    D.A. Kiselev

    2016-10-01

    Full Text Available The thickness dependent of electrical and piezoelectric properties of lead-free ferroelectric Ba0.8Sr0.2TiO3 thin films is reported. Ba0.8Sr0.2TiO3 (BST 80/20 thin films for various thickness, ranging from 150 nm to 550 nm, were prepared by high-frequency reactive sputtering of a ceramic target in an oxygen atmosphere on p-type Si substrate. Memory windows and effective dielectric constant of the BST film in Au/BST/Si thin film capacitors is found to increase with the increasing thickness of the film. Domain structure, domain switching and hysteresis loops of the BST 80/20 thin film were investigate via the piezoresponse force microscopy. Complete domain switching and strong piezoresponse are found in the ferroelectric BST film. The piezoelectric coefficient ( and the remnant piezoelectric response (ΔPR of BST 80/20 films is found to increase with the thickness of the film.

  20. Frequency Dependent Non- Thermal Effects of Oscillating Electric Fields in the Microwave Region on the Properties of a Solvated Lysozyme System: A Molecular Dynamics Study

    Science.gov (United States)

    Floros, Stelios; Liakopoulou-Kyriakides, Maria; Karatasos, Kostas

    2017-01-01

    The use of microwaves in every day’s applications raises issues regarding the non thermal biological effects of microwaves. In this work we employ molecular dynamics simulations to advance further the dielectric studies of protein solutions in the case of lysozyme, taking into consideration possible frequency dependent changes in the structural and dynamic properties of the system upon application of electric field in the microwave region. The obtained dielectric spectra are identical with those derived in our previous work using the Fröhlich-Kirkwood approach in the framework of the linear response theory. Noticeable structural changes in the protein have been observed only at frequencies near its absorption maximum. Concerning Cα position fluctuations, different frequencies affected different regions of the protein sequence. Furthermore, the influence of the field on the kinetics of protein-water as well as on the water-water hydrogen bonds in the first hydration shell has been studied; an extension of the Luzar-Chandler kinetic model was deemed necessary for a better fit of the applied field results and for the estimation of more accurate hydrogen bond lifetime values. PMID:28129348

  1. Intermittent Theta-Burst Transcranial Magnetic Stimulation Alters Electrical Properties of Fast-Spiking Neocortical Interneurons in an Age-Dependent Fashion

    Directory of Open Access Journals (Sweden)

    Kathrin eHoppenrath

    2016-03-01

    Full Text Available Modulation of human cortical excitability by repetitive transcranial magnetic stimulation (rTMS appears to be in part related to changed activity of inhibitory systems. Our own studies showed that intermittent theta-burst stimulation (iTBS applied via rTMS to rat cortex primarily affects the parvalbumin-expressing (PV fast-spiking interneurons (FSIs, evident via a strongly reduced PV expression. We further found the iTBS effect on PV to be age-dependent since no reduction in PV could be induced before the perineuronal nets (PNNs of FSIs start to grow around postnatal day 30. To elucidate possible iTBS-induced changes in the electrical properties of FSIs and cortical network activity during cortical critical period, we performed ex vivo – in vitro whole-cell patch clamp recordings from pre-labelled FSIs in the current study. FSIs of verum iTBS-treated rats displayed a higher excitability than sham-treated controls at PD29-38, evident as higher rates of induced action potential firing at low current injections (100-200 pA and a more depolarized resting membrane potential. This effect was absent in younger (PD26-28 and older animals (PD40-62. Slices of verum iTBS-treated rats further showed higher rates of spontaneous EPSCs. Based on these and previous findings we conclude that FSIs are particularly sensitive to theta-burst stimulation during early cortical development, when FSIs show an activity-driven step of maturation which is paralleled by intense growth of the PNNs and subsequent closure of the cortical critical period. Although to be proven further, rTMS may be a possible early intervention to compensate for hypo-activity related mal-development of cortical neuronal circuits.

  2. Intermittent Theta-Burst Transcranial Magnetic Stimulation Alters Electrical Properties of Fast-Spiking Neocortical Interneurons in an Age-Dependent Fashion.

    Science.gov (United States)

    Hoppenrath, Kathrin; Härtig, Wolfgang; Funke, Klaus

    2016-01-01

    Modulation of human cortical excitability by repetitive transcranial magnetic stimulation (rTMS) appears to be in part related to changed activity of inhibitory systems. Our own studies showed that intermittent theta-burst stimulation (iTBS) applied via rTMS to rat cortex primarily affects the parvalbumin-expressing (PV) fast-spiking interneurons (FSIs), evident via a strongly reduced PV expression. We further found the iTBS effect on PV to be age-dependent since no reduction in PV could be induced before the perineuronal nets (PNNs) of FSIs start to grow around postnatal day (PD) 30. To elucidate possible iTBS-induced changes in the electrical properties of FSIs and cortical network activity during cortical critical period, we performed ex vivo-in vitro whole-cell patch clamp recordings from pre-labeled FSIs in the current study. FSIs of verum iTBS-treated rats displayed a higher excitability than sham-treated controls at PD29-38, evident as higher rates of induced action potential firing at low current injections (100-200 pA) and a more depolarized resting membrane potential. This effect was absent in younger (PD26-28) and older animals (PD40-62). Slices of verum iTBS-treated rats further showed higher rates of spontaneous excitatory postsynaptic currents (sEPSCs). Based on these and previous findings we conclude that FSIs are particularly sensitive to TBS during early cortical development, when FSIs show an activity-driven step of maturation which is paralleled by intense growth of the PNNs and subsequent closure of the cortical critical period. Although to be proven further, rTMS may be a possible early intervention to compensate for hypo-activity related mal-development of cortical neuronal circuits.

  3. Electrical properties of polar membranes

    CERN Document Server

    Mosgaard, Lars D; Heimburg, Thomas

    2014-01-01

    Biological membranes are capacitors that can be charged by applying a field across the membrane. The charges on the capacitor exert a force on the membrane that leads to electrostriction, i.e. a thinning of the membrane. Since the force is quadratic in voltage, negative and positive voltage have an identical influence on the physics of symmetric membranes. However, this is not the case for a membrane with an asymmetry leading to a permanent electric polarization. Positive and negative voltages of identical magnitude lead to different properties. Such an asymmetry can originate from a lipid composition that is different on the two monolayers of the membrane, or from membrane curvature. The latter effect is called 'flexoelectricity'. As a consequence of permanent polarization, the membrane capacitor is discharged at a voltage different from zero. This leads to interesting electrical phenomena such as outward or inward rectification of membrane permeability. Here, we introduce a generalized theoretical framework...

  4. Electrical properties of seafloor massive sulfides

    Science.gov (United States)

    Spagnoli, Giovanni; Hannington, Mark; Bairlein, Katharina; Hördt, Andreas; Jegen, Marion; Petersen, Sven; Laurila, Tea

    2016-06-01

    Seafloor massive sulfide (SMS) deposits are increasingly seen as important marine metal resources for the future. A growing number of industrialized nations are involved in the surveying and sampling of such deposits by drilling. Drill ships are expensive and their availability can be limited; seabed drill rigs are a cost-effective alternative and more suitable for obtaining cores for resource evaluation. In order to achieve the objectives of resource evaluations, details are required of the geological, mineralogical, and physical properties of the polymetallic deposits and their host rocks. Electrical properties of the deposits and their ore minerals are distinct from their unmineralized host rocks. Therefore, the use of electrical methods to detect SMS while drilling and recovering drill cores could decrease the costs and accelerate offshore operations by limiting the amount of drilling in unmineralized material. This paper presents new data regarding the electrical properties of SMS cores that can be used in that assessment. Frequency-dependent complex electrical resistivity in the frequency range between 0.002 and 100 Hz was examined in order to potentially discriminate between different types of fresh rocks, alteration and mineralization. Forty mini-cores of SMS and unmineralized host rocks were tested in the laboratory, originating from different tectonic settings such as the intermediate-spreading ridges of the Galapagos and Axial Seamount, and the Pacmanus back-arc basin. The results indicate that there is a clear potential to distinguish between mineralized and non-mineralized samples, with some evidence that even different types of mineralization can be discriminated. This could be achieved using resistivity magnitude alone with appropriate rig-mounted electrical sensors. Exploiting the frequency-dependent behavior of resistivity might amplify the differences and further improve the rock characterization.

  5. Frequency and voltage dependence of electric and dielectric properties of Au/TiO2/n-4H-SiC (metal-insulator-semiconductor) type Schottky barrier diodes

    Science.gov (United States)

    Tanrıkulu, E. E.; Yıldız, D. E.; Günen, A.; Altındal, Ş.

    2015-09-01

    The main electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type Schottky barrier diodes (SBDs) have been investigated as functions of frequency and applied bias voltage. We believe that the use of high dielectric interfacial layer between metal and semiconductor can improve the performance of Schottky diodes. From the experimental data, both electrical and dielectric parameters were found as strong function of frequency and applied bias voltage. The Fermi energy level (EF), the concentration of doping donor atoms (P), barrier height (ΦB) and series resistance (Rs) values were obtained from reverse and forward bias C-V characteristics. The changes in EF and ND with frequency are considerably low. Therefore, their values were taken at about constant. The real and imaginary parts of dielectric constant (\\varepsilon \\prime , \\varepsilon \\prime\\prime ), tangent loss (tanδ), ac electrical conductivity (σac), and real and imaginary parts of electric modulus (M‧ and M″) values were also obtained from reverse and forward bias C-V and G/ω-V characteristics. In addition, the voltage dependent profiles of all these electrical and dielectric parameters were drawn for each frequency. These results confirmed that both electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type SBD are quite sensitive to both the frequency and applied bias voltage due to surface polarization, density distribution of interface traps (Dit), and interfacial layer.

  6. Dependence of the electrical and optical properties on the bias voltage for ZnO:Al films deposited by r.f. magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae-Hyeong [School of Electronics and Information Engineering, Kunsan National University, Kunsan (Korea, Republic of)], E-mail: jhyi@kunsan.ac.kr; Song, Jun-Tae [School of Information and Communication Engineering, Sungkyunkwan University, Suwon (Korea, Republic of)

    2008-02-15

    Aluminum-doped zinc oxide (ZnO:Al) thin films were deposited on glass, polycarbonate (PC), and polyethylene terephthalate (PET) substrates by r.f. magnetron sputtering. The substrate dc bias voltage varied from 0 V to 50 V. Structural, electrical and optical properties of the films were investigated. The deposition rate of ZnO:Al films on glass substrate initially increased with the bias voltage, and then decreased with further increasing bias voltage. It was found that the best films on glass substrate with a low as 6.2 x 10{sup -4} {omega} cm and an average transmittance over 80% at the wavelength range of 500-900 nm can be obtained by applying the bias voltage of 30 V. The properties of the films deposited on polymer substrate, such as PC and PET, have a similar tendency, with slightly inferior values to those on glass substrate.

  7. Composition dependent interfacial thermal stability, band alignment and electrical properties of Hf{sub 1−x}Ti{sub x}O{sub 2}/Si gate stacks

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.W. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230039 (China); He, G., E-mail: hegang@ahu.edu.cn [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230039 (China); National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai Institute of Technical Physics, 500 Yutian Road, Shanghai 200083 (China); Liu, M., E-mail: mliu@issp.ac.cn [Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Chen, H.S.; Liu, Y.M.; Sun, Z.Q. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230039 (China); Chen, X.S. [National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai Institute of Technical Physics, 500 Yutian Road, Shanghai 200083 (China)

    2015-08-15

    Highlights: • Sputtered Hf{sub 1−x}Ti{sub x}O{sub 2} gate dielectrics with different TiO{sub 2} concentration have been deposited on Si substrates. • Decrease in interfacial layer thickness reduction in band gap with increasing the TiO{sub 2} component has been determined. • Hf{sub 1−x}Ti{sub x}O{sub 2} with incorporating TiO{sub 2} of 9% shows to be a promising candidate for high-k gate dielectrics. - Abstract: The optical properties, interface chemistry and band alignment of Hf{sub 1−x}Ti{sub x}O{sub 2} (x = 0.03, 0.08, 0.12 and 0.20) high-k gate dielectric thin films, deposited by RF sputtering on Si substrate, have been systematically investigated. The effect of TiO{sub 2} incorporation on the interfacial chemical structure and energy-band discontinuities has been investigated by using X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectroscopy (UV–vis). It has been found that the band gap and band offsets of the Hf{sub 1−x}Ti{sub x}O{sub 2} thin film decrease with the increase of TiO{sub 2} concentration. Meanwhile, the obtained band offsets are all over 1 eV. Thin film capacitors fabricated with the MOS configuration of Al/Hf{sub 1−x}Ti{sub x}O{sub 2}/n-Si/Al exhibits excellent electrical properties with low interface state density, hysteresis voltage and low leakage current density. The suitable band gap, symmetrical band offsets relative to Si and prominent electrical properties render sputtering-derived Hf{sub 1−x}Ti{sub x}O{sub 2} with 9% TiO{sub 2} films as promising candidates for high-k gate dielectrics.

  8. Dependence of B1+ and B1− Field Patterns of Surface Coils on the Electrical Properties of the Sample and the MR Operating Frequency

    Science.gov (United States)

    Vaidya, Manushka V.; Collins, Christopher M.; Sodickson, Daniel K.; Brown, Ryan; Wiggins, Graham C.; Lattanzi, Riccardo

    2016-01-01

    In high field MRI, the spatial distribution of the radiofrequency magnetic (B1) field is usually affected by the presence of the sample. For hardware design and to aid interpretation of experimental results, it is important both to anticipate and to accurately simulate the behavior of these fields. Fields generated by a radiofrequency surface coil were simulated using dyadic Green’s functions, or experimentally measured over a range of frequencies inside an object whose electrical properties were varied to illustrate a variety of transmit (B1+) and receive (B1−) field patterns. In this work, we examine how changes in polarization of the field and interference of propagating waves in an object can affect the B1 spatial distribution. Results are explained conceptually using Maxwell’s equations and intuitive illustrations. We demonstrate that the electrical conductivity alters the spatial distribution of distinct polarized components of the field, causing “twisted” transmit and receive field patterns, and asymmetries between |B1+| and |B1−|. Additionally, interference patterns due to wavelength effects are observed at high field in samples with high relative permittivity and near-zero conductivity, but are not present in lossy samples due to the attenuation of propagating EM fields. This work provides a conceptual framework for understanding B1 spatial distributions for surface coils and can provide guidance for RF engineers.

  9. Dependence of B1+ and B1- Field Patterns of Surface Coils on the Electrical Properties of the Sample and the MR Operating Frequency.

    Science.gov (United States)

    Vaidya, Manushka V; Collins, Christopher M; Sodickson, Daniel K; Brown, Ryan; Wiggins, Graham C; Lattanzi, Riccardo

    2016-02-01

    In high field MRI, the spatial distribution of the radiofrequency magnetic ( B1) field is usually affected by the presence of the sample. For hardware design and to aid interpretation of experimental results, it is important both to anticipate and to accurately simulate the behavior of these fields. Fields generated by a radiofrequency surface coil were simulated using dyadic Green's functions, or experimentally measured over a range of frequencies inside an object whose electrical properties were varied to illustrate a variety of transmit [Formula: see text] and receive [Formula: see text] field patterns. In this work, we examine how changes in polarization of the field and interference of propagating waves in an object can affect the B1 spatial distribution. Results are explained conceptually using Maxwell's equations and intuitive illustrations. We demonstrate that the electrical conductivity alters the spatial distribution of distinct polarized components of the field, causing "twisted" transmit and receive field patterns, and asymmetries between [Formula: see text] and [Formula: see text]. Additionally, interference patterns due to wavelength effects are observed at high field in samples with high relative permittivity and near-zero conductivity, but are not present in lossy samples due to the attenuation of propagating EM fields. This work provides a conceptual framework for understanding B1 spatial distributions for surface coils and can provide guidance for RF engineers.

  10. Study of the electrical, thermal and chemical properties of Pd ohmic contacts to p-type 4H-SiC: dependence on annealing conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kassamakova, L.; Kakanakov, R. [Inst. of Appl. Phys., Plovdiv (Bulgaria). BAS; Nordell, N.; Savage, S. [Industrial Microelectronics Center, Kista (Sweden); Kakanakova-Georgieva, A.; Marinova, Ts. [Inst. of General and Inorganic Chemistry, BAS, Sofia (Bulgaria)

    1999-07-30

    The electrical and chemical properties of Pd ohmic contacts to p-type 4H-SiC, together with their thermal stability, have been studied in the annealing temperature range 600 - 700 C. The ohmic behaviour of as-deposited and annealed contacts has been checked from I - V characteristics and the contact resistivity has been determined by the linear TLM method in order to determine the electrical properties and the thermal stability. An ohmic behaviour was established after annealing at 600 C, while the lowest contact resistivity 5.5 x 10{sup -5} {omega}cm{sup 2} was obtained at 700 C. The contact structure, before and after annealing, was investigated using X-ray photoelectron spectroscopy depth analysis. As-deposited Pd films form an abrupt and chemically inert Pd/SiC interface. Annealing causes the formation of palladium silicide. After formation at 600 C the contact structure consists of unreacted Pd and Pd{sub 3}Si. During annealing at 700 C. Pd and SiC react completely and a mixture of Pd{sub 3}Si, Pd{sub 2}Si and C in a graphite state is found in the contact layer. The examination of the thermal stability shows that after a 100 h heating at 500 C, only the contacts annealed at 700 C did not suffer from a change in resistivity. This can be explained by a more complete reaction between the Pd contact layer and the SiC substrate at this higher annealing temperature. (orig.)

  11. Time-dependent correlations in electricity markets

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez-Ramirez, Jose; Escarela-Perez, Rafael [Departamento de Energia, Universidad Autonoma Metropolitana, Mexico DF, 09340 (Mexico)

    2010-03-15

    In the last years, many electricity markets were subjected to deregulated operation where prices are set by the action of market participants. In this form, producers and consumers rely on demand and price forecasts to decide their bidding strategies, allocate assets, negotiate bilateral contracts, hedge risks, and plan facility investments. A basic feature of efficient market hypothesis is the absence of correlations between price increments over any time scale leading to random walk-type behavior of prices, so arbitrage is not possible. However, recent studies have suggested that this is not the case and correlations are present in the behavior of diverse electricity markets. In this paper, a temporal quantification of electricity market correlations is made by means of detrended fluctuation and Allan analyses. The approach is applied to two Canadian electricity markets, Ontario and Alberta. The results show the existence of correlations in both demand and prices, exhibiting complex time-dependent behavior with lower correlations in winter while higher in summer. Relatively steady annual cycles in demand but unstable cycles in prices are detected. On the other hand, the more significant nonlinear effects (measured in terms of a multifractality index) are found for winter months, while the converse behavior is displayed during the summer period. In terms of forecasting models, our results suggest that nonlinear recursive models (e.g., feedback NNs) should be used for accurate day-ahead price estimation. In contrast, linear models can suffice for demand forecasting purposes. (author)

  12. Strain-dependent magnetism and electric transport properties of La{sub 0.7}Sr{sub 0.3}CoO{sub 3} films

    Energy Technology Data Exchange (ETDEWEB)

    Herklotz, Andreas; Rata, Diana; Bilani, Orkidia; Schultz, Ludwig; Doerr, Kathrin [IFW-Dresden, Helmholtzstrass e 20, 01069 Dresden (Germany)

    2008-07-01

    The electronic and magnetic properties of some perovskite-type 3d transition metal oxides are known to be sensitive to epitaxial strain. In order to investigate the influence of strain in La{sub 0.7}Sr{sub 0.3}CoO{sub 3} (LSCO) compound, epitaxial films under different biaxial strain have been grown using various substrates. Additionally, piezoelectric substrates of the composition 0.72PbMg{sub 1/3}Nb{sub 2/3}O{sub 3}-0.28PbTiO{sub 3} (PMN-28%PT) were employed to control the in-plane strain dynamically by applying an electrical field. An insulator-type behaviour was observed in films grown under tensile strain, whereas compressed films show bulk, metallic properties. This drastic influence of strain was confirmed by using the PMN-PT substrates, where a reversible strain of 0.15% caused a resistance change of one order of magnitude at room temperature. On the contrary, the magnetization data revealed a rather small impact of tensile strain on the magnetic behaviour of LSCO films. We suggest that the insulator state of La{sub 0.7}Sr{sub 0.3}CoO{sub 3} is caused by a stain-induced static Jahn-Teller-type deformation of the CoO{sub 6} units, which may be efficient as a localization mechanism.

  13. Optical and Electrical Properties of Nanostructured Metallic Electrical Contacts

    CERN Document Server

    Toranzos, Victor J; Mochán, W Luis; Zerbino, Jorge O

    2016-01-01

    We study the optical and electrical properties of silver films with a graded thickness obtained through metallic evaporation in vacuum on a tilted substrate to evaluate their use as semitransparent electrical contacts. We measure their ellipsometric coefficients, optical transmissions and electrical conductivity for different widths, and we employ an efficient recursive method to calculate their macroscopic dielectric function, their optical properties and their microscopic electric fields. The topology of very thin films corresponds to disconnected islands, while very wide films are simply connected. For intermediate widths the film becomes semicontinuous, multiply connected, and its microscopic electric field develops hotspots at optical resonances which appear near the percolation threshold of the conducting phase, yielding large ohmic losses that increase the absorptance above that of a corresponding homogeneous film. Optimizing the thickness of the film to maximize its transmittance above the percolation...

  14. Synthesis, characterization, temperature dependent electrical and magnetic properties of Ca3Co4O9 by a starch assisted sol-gel combustion method

    Science.gov (United States)

    Agilandeswari, K.; Ruban Kumar, A.

    2014-09-01

    In this present work we discussed the synthesis of pure Ca3Co4O9 ceramic powder by a starch assisted sol-gel combustion method. The products were characterized by powder X-ray diffraction (XRD), thermogravimetric and differential thermal analyses (TGA-DTA), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscope (SEM) and UV-visible diffuse reflectance spectroscopy (DRS). X-ray diffraction pattern confirmed the formation of single phase Ca3Co4O9 at a sintering temperature of 1073 K, and it is also confirmed in the thermal analysis. SEM images indicate the presence of diffused microporous sphere like morphology and the grain sizes are in the range of 150-300 nm. Optical properties of Ca3Co4O9 ceramic show a band gap at an energy level of 2.10 eV. A maximum electrical resistivity of 0.002 mΩ cm was exhibited by Ca3Co4O9 that was decreased to 0.0012 mΩ cm, when the temperature increased from 300 K to 473 K. Dielectric studies were conducted at various temperatures from room temperature to 673 K and the results indicate that the space charge polarization contributes to the conduction mechanism. It also shows that the dielectric relaxation with activation energy is 0.96 eV. The magnetic properties as a function of temperature represent the ferri-paramagnetic phase transition at above 50 K. M-H curve shows the hysteresis loop with saturation magnetization (Ms) and confirms the presence of soft magnetic materials.

  15. Fractal characteristics of electric properties of coal

    Institute of Scientific and Technical Information of China (English)

    LIU Cheng-lun; XU Long-jun; XIAN Xue-fu

    2006-01-01

    In the light of fractal geometry theory, the characteristics of coal's electric parameters (including dielectric constant, alternating conductivity, dielectric loss angle tangent and electric polarization constant) were studied by using literature data. The results are shown that the electrical properties of coal have fractal characteristic. The fractal dimensions of dielectric, alternating conductivity, dielectric loss angle tangent were obtained, and are relative to the content of pyrite sulfur, heat and ash content of coal.

  16. Innovative processing for improved electrical steel properties

    OpenAIRE

    Schneider, J; Barros-Lorenzo, J.; Infante-Danzo, I.; Verbeken, K.; Houbaert, Y.

    2010-01-01

    Electrical steel grades are the normal construction material for electrical motors and transformers because of their enhanced soft magnetic properties. One of the current trends in their production aims for increasing the silicon and/or aluminum concentration (above 3 wt %) to reduce magnetic losses through increased electrical resistivity. This is very difficult to realize by conventional processing, mainly because of cracking during cold rolling. An alternative production route is proposed ...

  17. Magnetic and Electric Properties of , ( Layered Perovskites

    Directory of Open Access Journals (Sweden)

    A. I. Ali

    2013-01-01

    Full Text Available The electric and magnetic properties of layered perovskites have been investigated systematically over the doping range . It was found that both Sr1.5Y0.5CoO4 and Sr1.4Y0.6CoO4 undergo ferromagnetic (FM transition around 145 K and 120 K, respectively. On the other hand, Sr1.3Y0.7CoO4 and Sr1.2Y0.8CoO4 compounds showed paramagnetic behavior over a wide range of temperatures. In addition, spin-glass transition ( was observed at 10 K for Sr1.3Y0.7CoO4. All investigated samples are semiconducting-like within the temperature range of 10–300 K. The temperature dependence of the electrical resistivity, , was described by two-dimensional variable range hopping (2D-VRH model at 50 K < ≤ 300 K. Comparison with other layered perovskites was discussed in this work.

  18. Optical and electrical properties of nanostructured metallic electrical contacts

    Science.gov (United States)

    Toranzos, Victor J.; Ortiz, Guillermo P.; Mochán, W. Luis; Zerbino, Jorge O.

    2017-01-01

    We study the optical and electrical properties of silver films with a graded thickness obtained through metallic evaporation in vacuum on a tilted substrate to evaluate their use as semitransparent electrical contacts. We measure their ellipsometric coefficients, optical transmissions and electrical conductivity for different widths, and we employ an efficient recursive method to calculate their macroscopic dielectric function, their optical properties and their microscopic electric fields. The topology of very thin films corresponds to disconnected islands, while very wide films are simply connected. For intermediate widths the film becomes semicontinuous, multiply connected, and its microscopic electric field develops hotspots at optical resonances which appear near the percolation threshold of the conducting phase, yielding large ohmic losses that increase the absorptance above that of a corresponding homogeneous film. Optimizing the thickness of the film to maximize its transmittance above the percolation threshold of the conductive phase we obtained a film with transmittance T  =  0.41 and a sheet resistance Rs\\text{max}≈ 2.7 Ω . We also analyze the observed emission frequency shift of porous silicon electroluminescent devices when Ag films are used as solid electrical contacts in replacement of electrolytic ones.

  19. Electrical properties of the potassium polytitanate compacts

    Energy Technology Data Exchange (ETDEWEB)

    Goffman, V.G.; Gorokhovsky, A.V. [NanoTechProm Ltd., Saratov (Russian Federation); Saratov State Technical University, Saratov (Russian Federation); Kompan, M.M. [Physico-Technical Institute of the Russian Academy of Science, St. Petersburg (Russian Federation); Tretyachenko, E.V.; Telegina, O.S.; Kovnev, A.V. [NanoTechProm Ltd., Saratov (Russian Federation); Saratov State Technical University, Saratov (Russian Federation); Fedorov, F.S., E-mail: fedorov_fs@daad-alumni.de [NanoTechProm Ltd., Saratov (Russian Federation); Saratov State Technical University, Saratov (Russian Federation)

    2014-12-05

    Highlights: • Quasi-static permittivity of potassium polytitanates compacts achieves 10{sup 4}–10{sup 5}. • Observed Maxwell–Wagner polarization attributes to layered structure of polytitanates. • The conductivity varies from 5 × 10{sup −2} to 10{sup −6}–10{sup −7} Sm/m in a wide range of temperatures. - Abstract: Titanates of alkali metals are widely applied materials as they are relatively low in cost and might be easily synthesized. They are utilized as adsorbents, catalysts, solid state electrolytes, superconductors. Here we report our results on electrical properties of the compacted amorphous potassium polytitanates powders. The electrical properties of the compacts were studied by means of complex impedance spectroscopy in a wide range of frequencies at different temperatures using two-electrode configuration. The frequency dependences of conductivity for the investigated potassium polytitanates compacts varies in the range from 5 × 10{sup −2} Sm/m (high frequencies, ion conductivity) up to 10{sup −6}–10{sup −7} Sm/m (low frequencies, electron conductivity) for a wide range of temperatures (19–150 °C). According to the results, at low frequencies quasi-static permittivity of the stabilized PPT compacts achieves high values of 10{sup 4}–10{sup 5}. This might be explained by Maxwell–Wagner polarization attributed to the layered structure of the potassium polytitanates particles containing potassium and hydronium ions together with crystallization water in the interlayer and is very promising for solid state electrolyte applications for moderate temperatures.

  20. Composition dependences of crystal structure and electrical properties of epitaxial Pb(Zr,Ti)O3 films grown on Si and SrTiO3 substrates

    Science.gov (United States)

    Okamoto, Shoji; Okamoto, Satoshi; Yokoyama, Shintaro; Akiyama, Kensuke; Funakubo, Hiroshi

    2016-10-01

    {100}-oriented Pb(Zr x ,Ti1- x )O3 (PZT) thin films of approximately 2 µm thickness and Zr/(Zr + Ti) ratios of 0.39-0.65 were epitaxially grown on (100)cSrRuO3//(100)SrTiO3 (STO) and (100)cSrRuO3//(100)cLaNiO3//(100)CeO2//(100)YSZ//(100)Si (Si) substrates having different thermal expansion coefficients by pulsed metal-organic chemical vapor deposition (MOCVD). The effects of Zr/(Zr + Ti) ratio and type of substrate on the crystal structure and dielectric, ferroelectric and piezoelectric properties of the films were systematically investigated. The X-ray diffraction measurement showed that both films changed from having a tetragonal symmetry to rhombohedral symmetry through the coexisting region with increasing Zr/(Zr + Ti) ratio. This region showed the Zr/(Zr + Ti) ratios of 0.45-0.59 for the films on the STO substrates that were wider than the films on the Si substrates. Saturation polarization values were minimum at approximately Zr/(Zr + Ti) = 0.50 for the films on the STO substrates, and no obvious Zr/(Zr + Ti) ratio dependence was detected in the films on the Si substrates. On the other hand, the maximum field-induced strain values measured by scanning force microscopy at approximately Zr/(Zr + Ti) = 0.50 at 100 kV/cm were about 0.5 and 0.1% in the films on the Si and STO, respectively.

  1. Symmetry Analysis of Spin-Dependent Electric Dipole and Its Application to Magnetoelectric Effects

    Science.gov (United States)

    Matsumoto, Masashige; Chimata, Kosuke; Koga, Mikito

    2017-03-01

    Spin-dependent electric dipole operators are investigated group-theoretically for the emergence of an electric dipole induced by a single spin or by two spins, where the spin dependences are completely classified up to the quadratic order. For a single spin, a product of spin operators behaves as an even-parity electric quadrupole operator, which differs from an odd-parity electric dipole. The lack of the inversion symmetry allows the even- and odd-parity mixing, which leads to the electric dipole described by the electric quadruple operators. Point-group tables are given for classification of the possible spin-dependent electric dipoles and for the qualitative analysis of multiferroic properties, such as an emergent electric dipole moment coexisting with a magnetic moment, electromagnon excitation, and directional dichroism. The results can be applied to a magnetic ion in crystals or embedded in molecules at a site without the inversion symmetry. In the presence of an inversion symmetry, the electric dipole does not appear for a single spin. This is not the case for the electric dipole induced by two spins with antisymmetric spin dependence, which is known as vector spin chirality, in the presence of the inversion center between the two spins. In the absence of the inversion center, symmetric spin-dependent electric dipoles are also relevant. The detailed analysis of various symmetries of two-spin states is applied to spin dimer systems and the related multiferroic properties.

  2. Field history dependence of nonlinear dielectric properties of Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} ceramics under bias electric field: Polarization behavior of polar nano-regions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaofei [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Xu Qing, E-mail: xuqing@whut.edu.c [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Liu Hanxing; Chen Wen [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 (China); Chen Min; Kim, Bok-Hee [Faculty of Advanced Materials Engineering, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2011-04-01

    Nonlinear dielectric properties of Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} ceramics prepared by citrate method were investigated under bias electric field with respect to field history. X-ray diffraction analysis and temperature dependence of the dielectric constant ({epsilon}{sub r}) confirmed a macroscopically paraelectric state for the specimen at room temperature. A slim polarization versus electric field (P-E) hysteresis loop of the specimen at room temperature indicated the existence of polar nano-regions (PNRs) superimposed on the paraelectric background. The nonlinear dielectric properties in continuous cycles of bias field sweep displayed a strong sensitivity to the field history. This phenomenon was qualitatively explained in terms of an irreversible polarization evolution of the PNRs under the bias fields. A considerable decline of the tunability with the cycle number suggests an appreciable contribution of the PNRs to the dielectric nonlinearity. The polarization and size of the PNRs were determined by fitting the dielectric constants to a multipolarization mechanism model.

  3. Electrical properties of mechanically activated zinc oxide

    Directory of Open Access Journals (Sweden)

    Vojisavljević K.

    2006-01-01

    Full Text Available Microstructural properties of a commercial zinc oxide powder were modified by mechanical activation in a high-energy vibro-mill. The obtained powders were dry pressed and sintered at 1100°C for 2 h. The electrical properties of grain boundaries of obtained ZnO ceramics were studied using an ac impedance analyzer. For that purpose, the ac electrical response was measured in the temperature range from 23 to 240°C in order to determine the resistance and capacitance of grain boundaries. The activation energies of conduction were obtained using an Arrhenius equation. Donor densities were calculated from Mott-Schottky measurements. The influence of microstructure, types and concentrations of defects on electrical properties was discussed.

  4. Frequency Dependent Electrical and Dielectric Properties of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky Barrier Diode

    Science.gov (United States)

    Taşçıoğlu, İ.; Tüzün Özmen, Ö.; Şağban, H. M.; Yağlıoğlu, E.; Altındal, Ş.

    2017-04-01

    In this study, poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester: 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (P3HT:PCBM:F4-TCNQ) organic film was deposited on n-type silicon (n-Si) substrate by spin coating method. The electrical and dielectric analysis of Au/P3HT:PCBM:F4-TCNQ/n-Si Schottky barrier diode was conducted by means of capacitance-voltage ( C- V) and conductance-voltage ( G/ ω- V) measurements in the frequency range of 10 kHz-2 MHz. The C- V- f plots exhibit fairly large frequency dispersion due to excess capacitance caused by the presence of interface states ( N ss). The values of N ss located in semiconductor bandgap at the organic film/semiconductor interface were calculated by Hill-Coleman method. Experimental results show that dielectric constant ( ɛ') and dielectric loss ( ɛ″) decrease with increasing frequency, whereas loss tangent (tan δ) remains nearly the same. The decrease in ɛ' and ɛ″ was interpreted by the theory of dielectric relaxation due to interfacial polarization. It is also observed that ac electrical conductivity ( σ ac) and electric modulus ( M' and M″) increase with increasing frequency.

  5. Magnetic and Electrical Properties of Leachate

    Directory of Open Access Journals (Sweden)

    Kartika Kirana

    2011-11-01

    Full Text Available Heavy metals content as well as magnetic and electrical properties of leachate from Sarimukti, West Java were studied in an attempt to seek correlation between heavy metals content and magnetic/electrical properties. Such correlation is expected to open the way for the use of magnetic/electrical properties as proxy indicators for the concentration of heavy metals in the leachate. The number of leachate samples studied is 21; 15 were taken spatially at depth of 1 m while the remaining 6 samples were taken vertically at a particular point. Measurement results showed that the heavy metals content in the leachate has a smaller concentration, except for Fe. The correlation between magnetic susceptibility and heavy metals content was found to be not so significant. The best correlation coefficient between magnetic susceptibility with heavy metals in leachate was found in Zn. Correlation between electrical conductivity and heavy metal is also not so significant, except for Zn and Cd. The use of magnetic properties as proxy indicator for heavy metals content in leachate is plausible provided that the magnetic susceptibility exceeds certain threshold value. Correlation between magnetic susceptibility, electrical conductivity and heavy metal content would be good if each quantity has a large value.

  6. EFFECT OF ELECTRIC FERTILIZER ON SOIL PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    WANG Ya-qin; WANG Ji-hong

    2004-01-01

    Electric fertilizer, I. E. Exerting electric field on plants during growing season instead of chemical fertilizer, is a kind of physical fertilizer, and the third kind of fertilizer with developmental prospect after inorganic fertilizer and organic fertilizer. For the purpose of studying the changes of physical and chemical properties of soil after exerting electric field, five treatments with different applications of chemical fertilizer were arranged on the black soil in Yushu City of Jilin Province by randomized block method, and electric field was exerted on plants every ten days during the growing season. Through sample analysis the paper arrives at following conclusions: 1) Exerting electric field can make soil's granular structure increase, bulk density decrease, moisture capacity increase,thus improving the perviousness of soil. 2) Exerting electric field can make microorganism's number increase and activity strengthen, thus activating nutrient and increasing organic matter content. 3) Exerting electric field with 0.1A medium has the best effect. So the chemical fertilizer can be saved. Therefore, we can say that the application of electric fertilizer is favorable for decreasing chemical poison, improving soil, relaxing the contradiction between the supply and demand of chemical fertilizer, and decreasing production cost of agriculture and forestry.

  7. Temperature-Dependent Dielectric Properties of Al/Epoxy Nanocomposites

    Science.gov (United States)

    Wang, Zijun; Zhou, Wenying; Sui, Xuezhen; Dong, Lina; Cai, Huiwu; Zuo, Jing; Chen, Qingguo

    2016-06-01

    Broadband dielectric spectroscopy was carried out to study the transition in electrical properties of Al/epoxy nanocomposites over the frequency range of 1-107 Hz and the temperature range of -20°C to 200°C. The dielectric permittivity, dissipation factor, and electrical conductivity of the nanocomposites increased with temperature and showed an abrupt increase around the glass transition temperature ( T g). The results clearly reveal an interesting transition of the electrical properties with increasing temperature: insulator below 70°C, conductor at about 70°C. The behavior of the transition in electrical properties of the nanocomposites was explored at different temperatures. The presence of relaxation peaks in the loss tangent and electric modulus spectra of the nanocomposites confirms that the chain segmental dynamics of the polymer is accompanied by the absorption of energy given to the system. It is suggested that the temperature-dependent transition of the electric properties in the nanocomposite is closely associated with the α-relaxation. The large increase in the dissipation factor and electric conductivity depends on the direct current conduction of thermally activated charge carriers resulting from the epoxy matrix above T g.

  8. Temperature dependence of electrical and thermal properties of Te{sub 82.2}Ge{sub 13.22}Si{sub 4.58} glassy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hegab, N.A.; Fadel, M.; Afifi, M.A.; Shawer, M.F. [Physics Department, Faculty of Education, Ain Shams University, Cairo (Egypt)

    2000-09-21

    Thin film and bulk samples were prepared from synthesized amorphous Te{sub 82.2}Ge{sub 13.22}Si{sub 4.58} chalcogenide glassy alloy by the thermal evaporation technique. X-ray analysis shows that both synthesized material and thin film forms have an amorphous nature. The electrical and thermal conductivities for the bulk sample were studied as a function of temperature in a range below T{sub g} (T{sub g}=423 K). The obtained results for electrical conductivity are explained in accordance with the Mott and Davis model. The switching effects in amorphous films were also investigated. The switching phenomenon for this composition was of memory type. The mean value of the threshold voltage V-bar{sub th} was found to increase linearly with increasing film thickness (98.9-250.1 nm), while it decreased exponentially with increasing temperature (below T{sub g}). The results obtained are explained in accordance with the electrothermal model for the switching process. (author)

  9. Universal size dependence of the physical properties of nanomaterials

    Science.gov (United States)

    Eremin, E. N.; Yurov, V. M.; Guchenko, S. A.; Laurynas, V. Ch

    2017-06-01

    Dimensional analysis of the experimentally observed dependence of the physical properties of nanoparticles, nanofilms and nanomaterials showed that there is a universal equation that accurately describes the observed size effects. It is shown that the size factor is also a universal value and is determined only by the atomic structure of the nanomaterial. Discovered universal relationships enable us to calculate the physical properties (mechanical, electrical, magnetic, thermal, etc.) of small particles and thin films based on knowledge of the properties of bulk materials.

  10. Innovative processing for improved electrical steel properties

    Energy Technology Data Exchange (ETDEWEB)

    Verbeken, K.; Infante-Danzo, I.; Barros-Lorenzo, J.; Schneider, J.; Houbaert, Y.

    2010-07-01

    Electrical steel grades are the normal construction material for electrical motors and transformers because of their enhanced soft magnetic properties. One of the current trends in their production aims for increasing the silicon and/or aluminum concentration (above 3 wt %) to reduce magnetic losses through increased electrical resistivity. This is very difficult to realize by conventional processing, mainly because of cracking during cold rolling. An alternative production route is proposed that raises the silicon and/or aluminum concentration by surface deposition of silicon and/or aluminum on a low-Si/low-Al steel substrate, e.g. by a short immersion in a molten Al-Si bath, followed by its diffusion into the bulk during subsequent annealing. This diffusion substantially modifies the microstructural features and therefore affects the mechanical and magnetic properties. Results of research efforts to optimize this production route and to understand the mechanisms and effects of the structural changes are presented and discussed. (Author).

  11. Temperature and frequency dependence on electrical properties of polyaniline/Ni{sub (1−x)}Co{sub x}Fe{sub 2}O{sub 4} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Chitra, Palanisamy [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Muthusamy, Athianna, E-mail: muthusrkv@gmail.com [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Dineshkumar, Sengottuvelu [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Jayaprakash, Rajan; Chandrasekar, J. [Department of Physics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India)

    2015-06-15

    Two nanocomposites of polyaniline (PANI) varying in their percentage composition of Ni{sub (1−x)}Co{sub x}Fe{sub 2}O{sub 4} nanoparticle (20%, 10% w/w of fine powders) were prepared by in-situ chemical oxidative polymerization method with and without ultrasonic treatment. The spinel ferrite nanoparticles of chemical composition Ni{sub (1−x)}Co{sub x}Fe{sub 2}O{sub 4} were prepared by auto combustion method. The structure and morphology of PANI and nanocomposites were characterized by X-ray diffraction (XRD) and High resolution transmission electron microscopy (HRTEM). The chemical structure of Ni{sub (1−x)}Co{sub x}Fe{sub 2}O{sub 4} nanoparticles and its composites were characterized by using Fourier transform infrared (FTIR), UV–visible absorption spectrometer and XRD techniques. Dielectric properties of nanocomposites at different temperature have been performed in the frequency range of 50 Hz to 5 MHz. Dielectric constant, dielectric loss and AC conductivity of PANI/Ni{sub (1−x)}Co{sub x}Fe{sub 2}O{sub 4} nanocomposites are significantly increasing with increase in ferrite content due to the polaron/bipolaron formation. The optical absorption experiments of PANI/Ni{sub (1−x)}Co{sub x}Fe{sub 2}O{sub 4} nanocomposite illustrate a direct transition with an energy band gap of Eg around 1.7. - Highlights: • The combustion reaction support to achieve less particle size. • The addition of sonic bath affects the properties. • Nature of the ferrites was affected with different composition of PANI.

  12. Temperature dependent electrical resistivity of liquid Sn

    Science.gov (United States)

    Prajapati, A. V.; Sonvane, Y. A.; Patel, H. P.; Thakor, P. B.

    2016-05-01

    The present paper deals with the effect of temperature variation on the electrical resistivity (ρ) of liquid Sn(Tin). We have used a new parameter free pseudopotential along with screening Taylor et al and Farid et al local field correction functions. The Percus-Yevick Hard Sphere (PYHS) reference system is used to describe structural information. Zeeman formula has been used for finding resistivity with the variation of temperature. The balanced harmonies between present data and experimental data have been achieved with a minimal deviation. So, we concluded that our newly constructed model potential is an effective one to produce the data of electrical resistivity of liquid Sn(Tin) as a function of temperature.

  13. Indications for a changing electricity demand pattern : The temperature dependence of electricity demand in the Netherlands

    NARCIS (Netherlands)

    Hekkenberg, M.; Benders, R. M. J.; Moll, H. C.; Uiterkamp, A. J. M. Schoot

    2009-01-01

    This study assesses the electricity demand pattern in the relatively temperate climate of the Netherlands (latitude 52 degrees 30'N). Daily electricity demand and average temperature during the period from 1970 until 2007 are investigated for possible trends in the temperature dependence of electric

  14. Modification of electrical properties of topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Peter Anand

    2017-08-29

    Ion implantation or deposition can be used to modify the bulk electrical properties of topological insulators. More particularly, ion implantation or deposition can be used to compensate for the non-zero bulk conductivity due to extrinsic charge carriers. The direct implantation of deposition/annealing of dopants allows better control over carrier concentrations for the purposes of achieving low bulk conductivity. Ion implantation or deposition enables the fabrication of inhomogeneously doped structures, enabling new types of device designs.

  15. Electrical properties of complex tungsten bronze ceramics

    Science.gov (United States)

    Padhee, R.; Das, Piyush R.

    2014-09-01

    This paper highlights the electrical properties of two new complex tungsten bronze ceramics (K2Pb2Eu2W2Ti4Nb4O30 and K2Pb2Pr2W2Ti4Nb4O30) which were prepared by high temperature mixed oxide method. Variation of impedance parameters with temperature (27-500 °C) and frequency (1 kHz to 5 MHz) shows the grain and grain boundary effects in the samples. The variation of dielectric parameters with frequency is also studied. The ac conductivity variation with temperature clearly exhibits that the materials have thermally activated transport properties of Arrhenius type.

  16. Electrical Properties of Composite Materials with Electric Field-Assisted Alignment of Nanocarbon Fillers

    Science.gov (United States)

    Yakovenko, Olena; Matzui, Ludmila; Danylova, Ganna; Zadorozhnii, Victor; Vovchenko, Ludmila; Perets, Yulia; Lazarenko, Oleksandra

    2017-07-01

    The article reports about electric field-induced alignment of the carbon nanoparticles embedded in epoxy matrix. Optical microscopy was performed to consider the effect of the electric field magnitude and configuration, filler morphology, and aspect ratio on alignment process. Characteristic time of aligned network formation was compared with modeling predictions. Carbon nanotube and graphite nanoplatelet rotation time was estimated using an analytical model based on effective medium approach. Different depolarization factor was applied according to the geometries of the particle and electric field. Solid nanocomposites were fabricated by using AC electric field. We have investigated concentration dependence of electrical conductivity of graphite nanoplatelets/epoxy composites using two-probe technique. It was established that the electrical properties of composites with random and aligned filler distribution are differ by conductivity value at certain filler content and distinguish by a form of concentration dependence of conductivity for fillers with different morphology. These differences were explained in terms of the dynamic percolation and formation of various conductive networks: chained in case of graphite nanoplatelets and crossed framework in case of carbon nanotubes filler.

  17. Electrical Properties of Composite Materials with Electric Field-Assisted Alignment of Nanocarbon Fillers.

    Science.gov (United States)

    Yakovenko, Olena; Matzui, Ludmila; Danylova, Ganna; Zadorozhnii, Victor; Vovchenko, Ludmila; Perets, Yulia; Lazarenko, Oleksandra

    2017-12-01

    The article reports about electric field-induced alignment of the carbon nanoparticles embedded in epoxy matrix. Optical microscopy was performed to consider the effect of the electric field magnitude and configuration, filler morphology, and aspect ratio on alignment process. Characteristic time of aligned network formation was compared with modeling predictions. Carbon nanotube and graphite nanoplatelet rotation time was estimated using an analytical model based on effective medium approach. Different depolarization factor was applied according to the geometries of the particle and electric field.Solid nanocomposites were fabricated by using AC electric field. We have investigated concentration dependence of electrical conductivity of graphite nanoplatelets/epoxy composites using two-probe technique. It was established that the electrical properties of composites with random and aligned filler distribution are differ by conductivity value at certain filler content and distinguish by a form of concentration dependence of conductivity for fillers with different morphology. These differences were explained in terms of the dynamic percolation and formation of various conductive networks: chained in case of graphite nanoplatelets and crossed framework in case of carbon nanotubes filler.

  18. Review on Optical and Electrical Properties of Conducting Polymers

    Directory of Open Access Journals (Sweden)

    Manisha Bajpai

    2016-01-01

    Full Text Available We reviewed optical and electrical properties of conjugated polymers. The charge transport models to describe the hole and electron transport mechanism are also included in the electrical properties of conjugated polymers. The effect of optical and electrical properties after doping is also indexed in this paper.

  19. PHEMTO: protein pH-dependent electric moment tools

    National Research Council Canada - National Science Library

    Kantardjiev, Alexander A; Atanasov, Boris P

    2009-01-01

    PHEMTO (protein pH-dependent electric moment tools) is released in response to the high demand in protein science community for evaluation of electrostatic characteristics in relations to molecular recognition...

  20. The Electrical and Dynamical Properties of Biomembranes

    DEFF Research Database (Denmark)

    Mosgaard, Lars Dalskov

    into account the coupling between thermodynamical uctuations and the available heat reservoir. The next step is to combine the knowledge on lipid membranes subjected to an electrical eld with the knowledge on their relaxation behavior and use our understanding to attempt to re-evaluate the results of common......-dimensional layers are literally vital for the cell, as membranes work as catalysts for some of the main chemical reactions involved in cell survival and homeostasis and govern all communication between a cell and its surroundings. The focus of the work presented in this thesis is to understand how...... the physical properties of lipid membranes relate to the behavior and functional properties of biological membranes, with special attention to the role of biological membranes in nerve signal propagation. We start by exploring the properties of polar lipid membranes in order to tackle the problem...

  1. Electrical properties of human skin as aging biomarkers.

    Science.gov (United States)

    Simić-Krstić, Jovana B; Kalauzi, Aleksandar J; Ribar, Srdjan N; Matija, Lidija R; Misevic, Gradimir N

    2014-09-01

    A non-invasive bioimpedance spectroscopy (BIS) and Cole-Cole impedance model parameters (R0, R∞, τ and α) were used to analyze electrical properties of intact and stripped human skin for both gender subjects divided into younger and older age groups. R0, R∞ and τ significantly increased while α significantly decreased with age in stripped skin for both genders (pCole-Cole parameters were age dependent with specific differences observed for genders and intact and stripped skin layers. Therefore, Cole-Cole parameters, obtained by non-invasive BIS measurements, are a new type of age dependent biomarkers.

  2. Surface and Electrical Properties of Electro-Coagulated Thermal Waste

    Science.gov (United States)

    Yesilkaya, S. S.; Okutan, M.; Içelli, O.; Yalçın, Z.

    2015-05-01

    The Electro-Coagulated Thermal Waste (ECTW) sample of the impedance spectroscopy investigation for electrical modulus and conductivity are presented. Electrical properties via temperature and frequency dependent impedance spectroscopy were investigated. Real and imaginary parts of electrical modulus were measured at various frequencies and a related Cole-Cole plot was acquired as well. The surface resistivity of the ECTW was measured by the four-point probe measurement technique, yielding a relatively high surface resistivity. As a result of this study, an effective building shielding material, which is a cost effective alternative, is proposed. The activation energy values were calculated from the Arrhenius plots at different frequencies. The transition region in this plot may be attributed to activation of ionic conductivity at lower temperatures.

  3. Electrical properties of covalently functionalized graphene

    Directory of Open Access Journals (Sweden)

    Paul Plachinda

    2017-02-01

    Full Text Available We have employed first-principle calculations to study transformation of graphene’s electronic structure under functionalization by covalent bonds with di erent atomic and molecular groups - epoxies, amines, PFPA. It is shown that this functionalization leads to an opening in the graphene’s band gap on order of tens meV, but also leads to reduction of electrical conductivity. We also discuss the influence of charge exchange between the functionalizing molecule and graphene’s conjugated electrons on electron transport properties.

  4. Electrical properties of carbon nanotubes in flowing vapor

    Institute of Scientific and Technical Information of China (English)

    XIAO Peng; WANG Xin-qiang; ZHANG Yun-huai

    2006-01-01

    Electric potentials were generated from carbon nanotubes immersed in flowing vapors.The nanomaterials used in this study were multiwall carbon nanotubes(MWCNTs) and silver nanopowders.These nanomaterials were dispersed and densely packed on a substrate and immersed in flowing vapors generated from solution such as water,ethanol and KCl.The potentials generated from these samples were measured by a voltmeter.Experimental results showed that the electric potentials were produced at the surface of the MWCNT samlpes,and strongly dependent on the pretreatment of MWCNT and properties of the flowing vapors.The mechanism of vapor-flow induced potentials may be ascribed to ions in the flowing vapors.This property of MWCNTs can advantage their application to nanoscale sensors,detectors and power cells.

  5. Magnetic and electrical properties of In doped cobalt ferrite nanoparticles

    Science.gov (United States)

    Nongjai, Razia; Khan, Shakeel; Asokan, K.; Ahmed, Hilal; Khan, Imran

    2012-10-01

    Nanoparticles of CoFe2O4 and CoIn0.15Fe1.85O4 ferrites were prepared by citrate gel route and characterized to understand their structural, electrical, and magnetic properties. X-ray diffraction and Raman spectroscopy were used to confirm the formation of single phase cubic spinel structure. The average grain sizes from the Scherrer formula were below 50 nm. Microstructural features were obtained by scanning electron microscope and compositional analysis by energy dispersive spectroscopy. The hysteresis curve shows enhancement in coercivity while reduction in saturation magnetization with the substitution of In3+ ions. Enhancement of coercivity is attributed to the transition from multidomain to single domain nature. Electrical properties, such as dc resistivity as a function of temperature and ac conductivity as a function of frequency and temperature were studied for both the samples. The activation energy derived from the Arrhenius equation was found to increase in the doped sample. The dielectric constant (ɛ') and dielectric loss (tan δ) are also studied as a function of frequency and temperature. The variation of dielectric properties ɛ', tan δ, and ac conductivity (σac) with frequency reveals that the dispersion is due to Maxwell-Wagner type of interfacial polarization in general and the hopping of charge between Fe2+ and Fe3+ as well as between Co2+ and Co3+ ions at B-sites. Magnetization and electrical property study showed its dominant dependence on the grain size.

  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. On the flow dependency of the electrical conductivity of blood

    NARCIS (Netherlands)

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

    2004-01-01

    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

  8. Electrical properties of ion irradiated polypropylene films

    Indian Academy of Sciences (India)

    N L Singh; Anita Sharma; V Shrinet; A K Rakshit; D K Avasthi

    2004-06-01

    The effect of high-energy (50 MeV) Li3+ ion beam irradiation on polypropylene (PP) film has been studied in the fluence range 2.4 × 1012-1.5 × 1014 ions/cm2. The a.c. electrical properties of PP films were measured in the frequency range from 0.05–100 kHz, and at temperature range between 30 and 140°C. This study indicates two peaks at 60°C and 120°C with comparatively high magnitudes. There is an exponential increase in conductivity with log of frequency and the effect is significant at higher fluences. The loss factor (tan ) vs frequency plot suggests that PP film based capacitors may be useful below 10 kHz. The capacitance is constant over a wide temperature range up to 130°C. FTIR spectra of the PP films before and after irradiation indicate that intensity of C–H stretching vibration at 2900 cm-1 is modified. The presence of many new peaks with the increase of fluence suggests the formation of alkanes and alkynes which might be responsible for the observed changes in the dielectric and electrical properties of PP films.

  9. Indications for a changing electricity demand pattern : The temperature dependence of electricity demand in the Netherlands

    NARCIS (Netherlands)

    Hekkenberg, M.; Benders, R. M. J.; Moll, H. C.; Uiterkamp, A. J. M. Schoot

    This study assesses the electricity demand pattern in the relatively temperate climate of the Netherlands (latitude 52 degrees 30'N). Daily electricity demand and average temperature during the period from 1970 until 2007 are investigated for possible trends in the temperature dependence of

  10. Electromobility in Germany: CO2 balance depends on charging electricity

    OpenAIRE

    Schill, Wolf-Peter; Gerbaulet, Clemens; Kasten, Peter

    2015-01-01

    The German government plans to significantly increase the deployment of electric vehicles. What impact would this have on the country’s power system and carbon emissions? This question was addressed as part of a European research project analyzing various scenarios up to 2030. One of the key findings of the study is that total annual power consumption of the four to five million electric vehicles (depending on the scenario) would be small. However, recharging the vehicles, particularly in an ...

  11. Temperature-dependent Raman spectra and electrical properties of 0.69Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.31PbTiO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Bijun [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Liu, Xing [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Li, Xiaobing; Zhao, Xiangyong; Luo, Haosu [Chinese Academy of Sciences, Key Laboratory of Inorganic Function Material and Device, Shanghai (China); Ding, Jianning [Changzhou University, School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovolatic Science and Engineering, Changzhou (China); Jiangsu University, School of Material Science and Engineering, Zhenjiang (China)

    2016-09-15

    The temperature-dependent Raman spectra and electrical properties of the 0.69Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.31PbTiO{sub 3} (0.69PMN-0.31PT) single crystals were investigated. Based on the group theory, the poled 0.69PMN-0.31PT single crystals belong to the monoclinic crystal system, which was confirmed by the room-temperature Raman spectra. The 0.69PMN-0.31PT single crystals experience successive structural phase transitions, i.e., a monoclinic-tetragonal (FE{sub M}-FE{sub T}) phase transition at T{sub M-T} and a tetragonal-cubic (FE{sub T}-P{sub C}) phase transition at T{sub m} determined by the dielectric measurement. Due to the enhancement of long-range order, their FE{sub M}-FE{sub T} phase transition becomes more obvious after the poling process. The wavenumbers and line widths of the 271, 502, 575, 795 cm{sup -1} Raman modes, and the intensity ratios of I{sub 271cm}{sup {sub -}{sub 1}}/I{sub 795cm}{sup {sub -}{sub 1}} and I{sub 502cm}{sup {sub -}{sub 1}}/I{sub 575cm}{sup {sub -}{sub 1}} exhibit obvious anomalies around T{sub M-T} and T{sub m}, which are closely related to the FE{sub M}-FE{sub T} and FE{sub T}-P{sub C} phase transitions. The temperature and electric field (E)-induced phase transitions are observed in the unipolar strain-E (S-E) curves. The converse piezoelectric constant (d{sub 33}), maximum strain value (S{sub max}%) and longitudinal electrostrictive coefficient (Q) increase considerably around the ferroelectric phase transition temperature T{sub M-T}. (orig.)

  12. Size dependent electrical and magnetic properties of ZnFe{sub 2}O{sub 4} nanoparticles synthesized by the combustion method: Comparison between aspartic acid and glycine as fuels

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugavani, A. [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Kalai Selvan, R., E-mail: selvankram@buc.edu.in [Solid State Ionics and Energy Devices Laboratory, Department of Physics, Bharathiar University, Coimbatore 641046 (India); Layek, Samar [Department of Physics, Indian institute of Technology, Kanpur 208016 (India); Sanjeeviraja, C. [Department of Physics, Alagappa Chettiar College of Engineering and Technology, Karaikudi- 630 004, Tamil Nadu (India)

    2014-03-15

    Using two different fuels such as aspartic acid and glycine, the spinel zinc ferrite nanoparticles were synthesized by the combustion method at different pH values. The thermochemical calculations for both the fuel assisted materials and its adiabatic flame temperature were calculated. The X-ray diffraction (XRD) pattern revealed the formation of single phase ZnFe{sub 2}O{sub 4} with high crystallinity. The characteristic functional groups of Fe3O and Zn3O were identified through FTIR analysis. Uniform size distribution of spherical particle in the average size range of 35–100 nm was inferred from SEM images. The room temperature DC conductivities of ZnFe{sub 2}O{sub 4} particles prepared by using aspartic and glycine are in the order of 10{sup −7} and 10{sup −8} respectively. The dielectric spectral analysis inferred that the obtained dielectric constant is high at low frequency and decreases with increase in frequency. This dielectric behavior is in accordance with the Maxwell–Wagner interfacial polarization. VSM and Mössbauer analysis revealed that the prepared material exhibits paramagnetic behavior and Fe{sup 3+} state of iron content in ZnFe{sub 2}O{sub 4} at room temperature. - Highlights: • For the first time aspartic acid is used as a fuel to synthesize ZnFe{sub 2}O{sub 4} nanoparticles. • Theoretical adiabatic flame temperature for the formation of ZnFe{sub 2}O{sub 4} is calculated. • Individual spherical shape particles are achieved by combustion synthesis. • Enhanced room temperature conductivity for aspartic acid assisted particles are revealed. • Size dependent electrical and magnetic properties are demonstrated.

  13. Polymers for electricity and electronics materials, properties, and applications

    CERN Document Server

    Drobny, Jiri George

    2011-01-01

    The comprehensive, practical book that explores the principles, properties, and applications of electrical polymers The electrical properties of polymers present almost limitless possibilities for industrial research and development, and this book provides an in-depth look at these remarkable molecules. In addition to traditional applications in insulating materials, wires, and cables, electrical polymers are increasingly being used in a range of emerging technologies. Presenting a comprehensive overview of how electrical polymers function and how they can be applied in the elec

  14. Vacuum radiation induced by time dependent electric field

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2017-04-01

    Full Text Available Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  15. Vacuum radiation induced by time dependent electric field

    Science.gov (United States)

    Zhang, Bo; Zhang, Zhi-meng; Hong, Wei; He, Shu-Kai; Teng, Jian; Gu, Yu-qiu

    2017-04-01

    Many predictions of new phenomena given by strong field quantum electrodynamics (SFQED) will be tested on next generation multi-petawatt laser facilities in the near future. These new phenomena are basis to understand physics in extremely strong electromagnetic fields therefore have attracted wide research interest. Here we discuss a new SFQED phenomenon that is named as vacuum radiation. In vacuum radiation, a virtual electron loop obtain energy from time dependent external electric field and radiate an entangled photon pair. Features of vacuum radiation in a locally time dependent electric field including spectrum, characteristic temperature, production rate and power are given.

  16. Engineering electrical properties of graphene: chemical approaches

    Science.gov (United States)

    Kim, Yong-Jin; Kim, Yuna; Novoselov, Konstantin; Hong, Byung Hee

    2015-12-01

    To ensure the high performance of graphene-based devices, it is necessary to engineer the electrical properties of graphene with enhanced conductivity, controlled work function, opened or closed bandgaps, etc. This can be performed by various non-covalent chemical approaches, including molecular adsorption, substrate-induced doping, polymerization on graphene, deposition of metallic thin films or nanoparticles, etc. In addition, covalent approaches such as the substitution of carbon atoms with boron or nitrogen and the functionalization with hydrogen or fluorine are useful to tune the bandgaps more efficiently, with better uniformity and stability. In this review, representative examples of chemically engineered graphene and its device applications will be reviewed, and remaining challenges will be discussed.

  17. Viscosity and electric properties of water aerosols

    Science.gov (United States)

    Shavlov, A. V.; Sokolov, I. V.; Dzhumandzhi, V. A.

    2016-09-01

    The flow of water mist in a narrow duct has been studied experimentally. The profile of the velocity of drops has been measured, and the viscosity of the mist has been calculated using the Navier-Stokes equation. It has been found that at low gradients of the rate of shear the viscosity of the mist can exceed that of clean air by tens and even hundreds of times. The electric charge of the drops has been measured. It has been found that the viscosity of the mist differs from that of clean air at gradients of the rate of shear that are less than the frequency of the establishment of electric equilibrium between the drops. A comparative analysis of the viscosities of the mist and a drop cluster has been carried out, and the dependence of the viscosity of the water aerosol on the radius and the charge of the drops has been predicted. The possible role of aerosols that contain submicron drops in the known "clear air turbulence" problem has been shown.

  18. Spin-dependent electrical transport in Fe-MgO-Fe heterostructures

    Directory of Open Access Journals (Sweden)

    A A Shokri

    2016-09-01

    Full Text Available In this paper, spin-dependent electrical transport properties are investigated in a single-crystal magnetic tunnel junction (MTJ which consists of two ferromagnetic Fe electrodes separated by an MgO insulating barrier. These properties contain electric current, spin polarization and tunnel magnetoresistance (TMR. For this purpose, spin-dependent Hamiltonian is described for Δ1 and Δ5 bands in the transport direction. The transmission is calculated by Green's function formalism based on a single-band tight-binding approximation. The transport properties are investigated as a function of the barrier thickness in the limit of coherent tunneling. We have demonstrated that dependence of the TMR on the applied voltage and barrier thickness. Our numerical results may be useful for designing of spintronic devices. The numerical results may be useful in designing of spintronic devices.

  19. Innovative processing for improved electrical steel properties

    Directory of Open Access Journals (Sweden)

    Schneider, J.

    2010-10-01

    Full Text Available Electrical steel grades are the normal construction material for electrical motors and transformers because of their enhanced soft magnetic properties. One of the current trends in their production aims for increasing the silicon and/or aluminum concentration (above 3 wt % to reduce magnetic losses through increased electrical resistivity. This is very difficult to realize by conventional processing, mainly because of cracking during cold rolling. An alternative production route is proposed that raises the silicon and/or aluminum concentration by surface deposition of silicon and/or aluminum on a low-Si/low-Al steel substrate, e.g. by a short immersion in a molten Al-Si bath, followed by its diffusion into the bulk during subsequent annealing. This diffusion substantially modifies the microstructural features and therefore affects the mechanical and magnetic properties. Results of research efforts to optimize this production route and to understand the mechanisms and effects of the structural changes are presented and discussed.Los aceros eléctricos se usan, normalmente, en la construcción de motores eléctricos y transformadores debido a sus suaves propiedades magnéticas. Una de las tendencias actuales es producir aceros con contenidos mayores de silicio y/o aluminio (por encima de un 3 %, en peso para reducir las pérdidas magnéticas a través del incremento de la resistividad eléctrica. Una de las desventajas de producir este tipo de aceros con altos contenidos de silicio y/o aluminio es el agrietamiento producido en el material durante el proceso de laminado en frío. Para incrementar el contenido de silicio y/o aluminio en aceros con bajos contenidos de estos elementos de aleación, se sugiere un procedimiento alternativo de producción que se basa, fundamentalmente, en depositar un recubrimiento rico en silicio y/o aluminio, en la superficie del acero. Por ejemplo, uno de los métodos utilizados es sumergir el material en una aleaci

  20. Electrical properties of methane hydrate + sediment mixtures

    Science.gov (United States)

    Du Frane, Wyatt L.; Stern, Laura A.; Constable, Steven; Weitemeyer, Karen A.; Smith, Megan M; Roberts, Jeffery J.

    2015-01-01

    Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. Toward this goal, we built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EM field surveys. Here we report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. These results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.

  1. Dependence of electric field on STM tip preparation

    DEFF Research Database (Denmark)

    Huang, D.H.; Grey, Francois; Aono, M.

    1998-01-01

    Voltage pulses applied between an STM tip and a surface can modify the surface on the nanometer scale due to electric-field-induced evaporation. However, at present, different groups have achieved surface modification with quite different bias conditions, and it is still difficult to obtain high...... reproducibility in such experiments. In this paper, we measure the tip displacement during a pulse at constant tunnelling current, and deduce that the electric field produced by the pulse depends in a systematic way on tip preparation, The results show how differences in tip preparation can be a major source...

  2. Electrical Transport Properties of Carbon Nanotube Metal-Semiconductor Heterojunction

    Science.gov (United States)

    Talukdar, Keka; Shantappa, Anil

    2016-10-01

    Carbon nanotubes (CNTs) have been proved to have promising applicability in various fields of science and technology. Their fascinating mechanical, electrical, thermal, optical properties have caught the attention of today’s world. We have discussed here the great possibility of using CNTs in electronic devices. CNTs can be both metallic and semiconducting depending on their chirality. When two CNTs of different chirality are joined together via topological defects, they may acquire rectifying diode property. We have joined two tubes of different chiralities through circumferential Stone-Wales defects and calculated their density of states by nearest neighbor tight binding approximation. Transmission function is also calculated to analyze whether the junctions can be used as electronic devices. Different heterojunctions are modeled and analyzed in this study. Internal stresses in the heterojunctions are also calculated by molecular dynamics simulation.

  3. Monitoring Method for the Electrical Properties of Piezoelectric Transducer

    Institute of Scientific and Technical Information of China (English)

    李文; 朱泽琪

    2012-01-01

    The monitoring of cutting force in a vibration cutting process has a great significance in the popularization of ultrasonic vibration cutting technology. A new monitoring method of which the cutting force of ultrasonic elliptic vibration cutting is monitored using the electrical properties of transducer was proposed by studying on the relationship of cutting force, transducer electric impedance and load. A measurement system was designed for the electrical properties of transducer. The feasibility of cutting force monitoring method based on the electrical properties of piezoelectric transducer was proved by the cutting experiments.

  4. The Effect of Radiations on the Structural and Electrical Properties of Device Technologies: Comparison and Trends

    OpenAIRE

    Jain, C.P.

    2014-01-01

    The effects of radiation on the structural and electrical properties of electronic devices are complex in nature and have changed much during decades of device evolution. These effects are mainly because of radiation induced charge build-up in oxide and interfacial regions. This paper presents a details of these radiation induced effects, their dependencies, and the change in structural properties and electrical characterises of different devices before and after irradiation are measured and ...

  5. Experimental analysis of electrical properties of composite materials

    Science.gov (United States)

    Fiala, L.; Rovnaník, P.; Černý, R.

    2017-02-01

    Dry cement-based composites are electrically non-conductive materials that behave in electric field like dielectrics. However, a relatively low amount of electrically conductive admixture significantly increases the electrical conductivity which extends applicability of such materials in practice. Therefore, they can be used as self-monitoring sensors controlling development of cracks; as sensors monitoring moisture content or when treated by an external electrical voltage as heat sources used for deicing of material's surface layer. Alkali-activated aluminosilicates (AAA), as competing materials to cement-based materials, are intensively investigated in the present due to their superior durability and environmental impact. Whereas the electrical properties of AAA are similar to those cement-based, they can be enhanced in the same way. In both cases, it is crucial to find a reasonable amount of electrically conductive phase to design composites with a sufficient electrical conductivity at an affordable price. In this paper, electrical properties of composites based on AAA binder and electrically conductive admixture represented by carbon nanotubes (CNT) are investigated. Measurements of electrical properties are carried out by means of 2-probes DC technique on nine types of samples; reference sample without the conductive phase and samples with CNT admixture in amount of 0.1 % - 2.5 % by vol. A significant increase of the electrical conductivity starts from the amount of 0.5 % CNT admixture and in case of 2.5 % CNT is about three orders of magnitude higher compared to the reference sample.

  6. Isospin dependent properties of asymmetric nuclear matter

    CERN Document Server

    Chowdhury, P Roy; Samanta, C

    2009-01-01

    The density dependence of nuclear symmetry energy is determined from a systematic study of the isospin dependent bulk properties of asymmetric nuclear matter using the isoscalar and the isovector components of density dependent M3Y interaction. The incompressibility $K_\\infty$ for the symmetric nuclear matter, the isospin dependent part $K_{asy}$ of the isobaric incompressibility and the slope $L$ are all in excellent agreement with the constraints recently extracted from measured isotopic dependence of the giant monopole resonances in even-A Sn isotopes, from the neutron skin thickness of nuclei and from analyses of experimental data on isospin diffusion and isotopic scaling in intermediate energy heavy-ion collisions. This work provides a fundamental basis for the understanding of nuclear matter under extreme conditions, and validates the important empirical constraints obtained from recent experimental data.

  7. A transition in mechanisms of size dependent electrical transport at nanoscale metal-oxide interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Jiechang; Nonnenmann, Stephen S.; Qin, Wei; Bonnell, Dawn A., E-mail: bonnell@lrsm.seas.upenn.edu [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2013-12-16

    As device miniaturization approaches nanoscale dimensions, interfaces begin to dominate electrical properties. Here the system archetype Au/SrTiO{sub 3} is used to examine the origin of size dependent transport properties along metal-oxide interfaces. We demonstrate that a transition between two classes of size dependent electronic transport mechanisms exists, defined by a critical size ε. At sizes larger than ε an edge-related tunneling effect proportional to 1/D (the height of the supported Au nanoparticle) is observed; interfaces with sizes smaller than ε exhibit random fluctuations in current. The ability to distinguish between these mechanisms is important to future developments in nanoscale device design.

  8. Electrical properties of self-assembled carbon networks

    Science.gov (United States)

    Govor, L. V.; Goldbach, M.; Bashmakov, I. A.; Butylina, I. B.; Parisi, J.

    2000-07-01

    In the past years, the interest in the physics of mesoscopic device structures has increased as the patterning of such systems became more and more applicable. Mesoscopic structures uncover new physics since size effects play an important role. For patterning, self-organizing processes are promising, but they can also bear difficulties. Self-organization phenomena are, however, interesting from a physical point of view and offer cheap possibilities for production purposes. But they are not totally regular, and one process is restrained to a limited number of structures and materials. For the understanding of the electrical behavior of these mesoscopic structures, the form and the slight variation of one from the other have to be taken into account as well as the material properties. In this paper, we present an electrical characterization of carbon networks produced by a self-organizing process. The net structure consists of hexagonal basis cells with a diameter of about 1 μm and the dimensions of the interconnections of about 100 nm. We find that in the temperature range from 4.2 to 150 K, the specific resistivity ρ depends on temperature T as ρ(T)~T-0.3 exp([T0/T]1/p) and the transport mechanism, therefore, is variable range hopping. For 4.2 Kchange of the factor n from 1 to 0 takes place with increasing electric field.

  9. Effect of Exposure to Electrical Discharge on Transformer Oil Properties

    Institute of Scientific and Technical Information of China (English)

    J. S. N'Cho; I. Fofana; T. Aka-Ngnui; A. Beroual

    2011-01-01

    Petroleum based oils, the so-called mineral oils, are used for impregnating solid insulations or filling products of very large number of electric materials: transformers, reactors, cables, bushings, circuit breakers, tap changers, etc. In these equipments, oil is exposed to electrical stress and may experience electrical discharges under certain circumstances. Since the electrical stress is unavoidable in power equipments, the ability of oil to resist decomposition under electrical stress is of great importance for the safety of these devices. Electrical stress together with heat and moisture, in the presence of oxygen, oxidises the oil producing free radicals, acids and sludge that are deleterious to the transformer. In this paper, the effect of electrical discharges on oil properties is reported. The results indicate that quality of oil is considerably affected with increasing voltage stress. Comparing oil properties before and after voltage application allows assessing the outcome of random secondary chemical reactions between large oil born free radicals.

  10. Elastic and Electrical Properties Evaluation of Low Resistivity Pays in Malay Basin Clastics Reservoirs

    Science.gov (United States)

    Almanna Lubis, Luluan; Ghosh, Deva P.; Hermana, Maman

    2016-07-01

    The elastic and electrical properties of low resistivity pays clastics reservoirs in Malay Basin are strongly dependent on the complex nature of the clay content, either dispersed or laminated/layered. Estimating the hydrocarbon pore volume from conventional electrical log, i.e. resistivity log, is quite a challenge. The low elastic impedance contrast also found as one of the challenge thus create a problem to map the distribution of the low resistivity reservoirs. In this paper, we evaluate the electrical properties and elastic rock properties to discriminate the pay from the adjacent cap rock or shale. Forward modeling of well log responses including electrical properties are applied to analyze the nature of the possible pays on laminated reservoir rocks. In the implementation of rock properties analysis, several conventional elastic properties are comparatively analyzed for the sensitivity and feasibility analysis on each elastic parameters. Finally, we discussed the advantages of each elastic parameters in detail. In addition, cross-plots of elastic and electrical properties attributes help us in the clear separation of anomalous zone and lithologic properties of sand and shale facies over conventional elastic parameter crossplots attributes. The possible relationship on electrical and elastic properties are discussed for further studies.

  11. Non-reproducible Electrical Properties Of Semiconductor PVDF-HFP (Hexafluoropropylenevinylidenefluoride) Copolymer

    Science.gov (United States)

    Likoglu, Gulbeden; Guney, H. Yuksel; Abaci, Ufuk

    2007-04-01

    The I-V characteristic of carbon black-filled PVDF-HFP copolymer has been investigated as functions of electrical field, temperature and time. In addition, the conductivity has been measured by applying fixed voltage at different temperature. Electrical properties of the carbon-black-filled PVDf-HFP have been compared with the electrical properties of pure PVDF and PVDF-HFP samples. The variation of conductivity with respect to electrical field and temperature has been obtained experimentally. Although the conductivity has been especially increasing with using temperature as semiconductor, it tends to decrease after a certain electrical field. Because of the dipolar structure, the I-V characteristic of the material has shown non-reproducible and hysteresis behavior. It has observed that the variation of conductivity as a function of temperature under fixed electrical field followed different exponential ways which depends on time after a certain temperature value.

  12. Grain size effect on magnetic and electric properties of LuMnO3 nanocrystalline materials

    Science.gov (United States)

    Han, Tai-Chun; Chen, Jia-Wern; Liu, Yuan-Hsun; Hu, Yu-Min

    2013-05-01

    Magnetic and electric properties are investigated for the nanosized LuMnO3 samples with different grain sizes (30 nm to 500 nm) synthesized by a modified Pechini method. It shows that magnetic and electric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 72 to 89 K. The temperature-dependent dielectric measurements show an anomaly in the dielectric constant at temperatures close to the AFM ordering temperature for all samples. A corresponding shift of the peak-positions of dielectric anomaly and magnetic ordering indicates a strong correlation between the magnetic ordering and the electric polarization. Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters.

  13. Comparison between the electrical properties of polyphenylacetylene and polyaminotriazole

    Directory of Open Access Journals (Sweden)

    M. Yahia Abed

    2014-03-01

    Full Text Available The electrical properties of a polymer containing aromatic rings were compared with those of polyheterocyclic compound. Each segment of the polyheterocyclic compound contains three nitrogen atoms. Both polymers were prepared at the laboratory. It was found that the specific electrical conductivity of polyphenylacetylene is higher than that of polyaminotriazole. Log ρ vs. 103/T was traced for both compounds, where ρ is the specific electrical resistivity and T is the absolute temperature. Complexes of each compound with KI were prepared. The electrical properties of these complexes were studied. The microstructure of both compounds was determined by FTIR spectroscopy.

  14. Temperature Dependence of Electrical Properties and Crystal Structure of 0.29Pb(In1/2Nb1/2O3–0.44Pb(Mg1/3Nb2/3O3–0.27PbTiO3 Single Crystals

    Directory of Open Access Journals (Sweden)

    Qian Li

    2013-01-01

    Full Text Available We characterized the temperature dependent (~25–200°C electromechanical properties and crystal structure of Pb(In1/2Nb1/2O3-Pb(Mg1/3Nb2/3O3-PbTiO3 single crystals using in situ electrical measurement and neutron diffraction techniques. The results show that the poled crystal experiences an addition phase transition around 120°C whereas such a transition is absent in the unpoled crystal. It is also found that the polar order persists above the maximum dielectric permittivity temperature at which the crystal shows a well-defined antiferroelectric behavior. The changes in the electrical properties and underlying crystal structure are discussed in the paper.

  15. Thermal and Electrical Properties of Electrides

    Science.gov (United States)

    Moeggenborg, Kevin James

    1990-01-01

    A method to determine the stability and decomposition kinetics of electrides was developed. The method uses DSC and was applied to two electrides. A sample of Li ^+(PMPCY)e^- underwent a first-order decomposition reaction with a half life of 110 hrs at 23^circC while a sample of K^+(C222)e ^- decomposed autocatalytically in under 2 days at -57^circ C. The results point to two different mechanisms of decomposition in electrides. The electrical properties of several electrides were investigated through Impedance Spectroscopy and a.c. and d.c. conductivity methods. D.C. conductivity studies of K^+(C222)e^- indicated a low band gap but high apparent resistivity and marked non-Ohmic behavior for the compound. The high resistivity and non-Ohmic behavior were found to be due to a Schottky barrier at the sample-electrode interface. Four probe a.c. conductivity experiments on a cylindrical sample pellet revealed a band gap of 0.086 eV for the compound and placed an upper limit of 0.189 Omega cm at 130 K on its resistivity. The band gap of the compound may be due to the activated transfer of electrons across grain boundaries in the polycrystalline samples. The electrides Cs^+(15C5) _2e^- and Cs^+(18C6)_2e ^- were shown to exhibit the first ionic conductivity ever seen in electrides. Cs ^+(15C5)_2e ^- undergoes a transition from defect electronic conductivity to ionic conductivity, the latter having an activation energy of 0.7 eV. Cs^+(18C6) _2e^- also exhibited ionic conduction with an activation energy of 1.0 eV. Both compounds exhibited electrochemical cell behavior when placed between one cesium and one stainless steel electrode. The mechanism of the ionic conductivity may involve the release of the cesium cation from its crown ether cage and its reduction by an electron anion of the compound followed by Cs^+ transfer between anionic sites in the crystal lattice. The semiconductor behavior previously seen in Cs^+(18C6) _2e^- was shown to be due to the doping of the

  16. Electrical properties of a-GeSe100-

    Indian Academy of Sciences (India)

    Abdolali Zolanvari; Navdeep Goyal; S K Tripathi

    2004-09-01

    In general, the conductivity in chalcogenide glasses at higher tempratures is dominated by band conduction (DC conduction). But, at lower tempratures, hoping conduction dominates over band conduction. A study at lower temprature can, eventually, provide useful information about the conduction mechanism and the defect states in the material. Therefore, the study of electrical properties of GeSe100- in the lower temperature region (room temperature) is interesting. Temperature and frequency dependence of GeSe100- ( = 15, 20 and 25) have been studied over different range of temperatures and frequencies. Am agreement between experimental and theoretical results suggested that the behaviour of germanium selenium system (GeSe100-) have been successfully explained by correlated barrier hopping (CBH) model.

  17. Electrical property sensing biopsy needle for prostate cancer detection.

    Science.gov (United States)

    Mishra, V; Schned, A R; Hartov, A; Heaney, J A; Seigne, J; Halter, R J

    2013-11-01

    Significant electrical property differences have been demonstrated to exist between malignant and benign prostate tissues. We evaluated how well a custom designed clinically deployable electrical property sensing biopsy needle is able to discriminate between these tissue types in an ex vivo prostate model. An electrical impedance spectroscopy (EIS) sensing biopsy (Bx) needle was developed to record resistive (ρR) and reactive (ρX) components of electrical impedance from 100 Hz to 1 MHz. Standard twelve-core biopsy protocols were followed, in which the EIS-Bx device was used to gauge electrical properties prior to extracting tissue cores through biopsy needle firing from 36 ex vivo human prostates. Histopathological assessment of the cores was statistically compared to the impedance spectrum gauged from each core. The magnitudes of the mean resistive and reactive components were significantly higher in cancer tissues (P biopsy procedures. © 2013 Wiley Periodicals, Inc.

  18. Study on the electrical properties of young concrete

    Institute of Scientific and Technical Information of China (English)

    金贤玉; 金南国; 李宗津

    2002-01-01

    The process of hydration and solidification of young concrete has significant effect on the long term strength and durability of concrete. The electrical property of concrete provides a direct and practical method for monitoring and investigating the hydration process of young concrete. This study developed an advanced system for measurement of electrical parameters, used to study the electrical properties of young concrete. The test results provided the electric parameters for concretes with different water binder ratios and different mineral admixture incorporations. The variations and characteristics of the measured electrical parameters were closely related to the physical and chemical properties of young concrete. These parameters were used to analyze and study the hydration process of young concrete.

  19. Electrical Properties of Zinc-Kaolin Composites below its Percolation ...

    African Journals Online (AJOL)

    Bheema

    In this paper, we present some electrical properties of the zinc-kaolin cermet resistors with zinc ... Most of the research works involving cermets have been on their electrical .... Where, Ea is the Activation energy of conductivity, k is the Boltzmann's constant, T is the ..... resources such as hydro, solar, wind and geothermal.

  20. Nonlinear electrical properties of Si three-terminal junction devices

    DEFF Research Database (Denmark)

    Fantao, Meng; Jie, Sun; Graczyk, Mariusz

    2010-01-01

    This letter reports on the realization and characterization of silicon three-terminal junction devices made in a silicon-on-insulator wafer. Room temperature electrical measurements show that the fabricated devices exhibit pronounced nonlinear electrical properties inherent to ballistic electron ...

  1. FABRICATION AND STUDY OF THE ELECTRICAL PROPERTIES ...

    African Journals Online (AJOL)

    DR. AMINU

    The resistance values fall with increasing firing temperature. All the resistors ... TFRs based on Bi2Ru2O7, exhibit a high stability and very low ... We must also realise that electrical behaviour is influenced ... copper leads were later soldered to.

  2. Spin-dependent electrical conduction in a pentacene Schottky diode explored by electrically detected magnetic resonance

    Science.gov (United States)

    Fukuda, Kunito; Asakawa, Naoki

    2017-02-01

    Reported is the observation of dark spin-dependent electrical conduction in a Schottky barrier diode with pentacene (PSBD) using electrically detected magnetic resonance at room temperature. It is suggested that spin-dependent conduction exists in pentacene thin films, which is explored by examining the anisotropic linewidth of the EDMR signal and current density-voltage (J-V) measurements. The EDMR spectrum can be decomposed to Gaussian and Lorentzian components. The dependency of the two signals on the applied voltage was consistent with the current density-voltage (J-V) of the PSBD rather than that of the electron-only device of Al/pentacene/Al, indicating that the spin-dependent conduction is due to bipolaron formation associated with hole polaronic hopping processes. The applied-voltage dependence of the ratio of intensity of the Gaussian line to the Lorentzian may infer that increasing current density should make conducting paths more dispersive, thereby resulting in an increased fraction of the Gaussian line due to the higher dispersive g-factor.

  3. Thermal to electricity conversion using thermal magnetic properties

    Science.gov (United States)

    West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID

    2010-04-27

    A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.

  4. Petroleum electrical properties characterization; Caracterizaco de propriedades eletricas de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Ueti, Edson; Sens, Marcio Antonio [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)], e-mail: ueti@cepel.br

    2006-07-01

    Presently, petroleum wells consist predominantly of heavy type petroleum, that is submitted to decantation and separation of water, through desalinisation process. If this process is not efficient, the metallic piping will be severely corroded during refining. Hence, the knowledge of petroleum electric properties is essential for optimizing the separation of water from petroleum, by indicating its humidity in laboratory testing conditions. The present work shows an experimental procedure based on disposable cells for electric characterization of liquid polymeric materials. The use of standard cells is unfeasible, due to the petroleum physical characteristics. The procedures for the evaluation of electric properties shown in this work are applied for dielectric constant values up to 200 kHz, as well as for the electric conductivity in direct current and the electrical strength in industrial frequency. (author)

  5. Pressure Dependent Electronic Properties of Organic Semiconductors from First Principles

    Science.gov (United States)

    Knuth, Franz; Carbogno, Christian; Blum, Volker; Scheffler, Matthias

    2015-03-01

    The electronic properties of organic semiconductors typically exhibit a significant dependence on the strain, stress, and pressure. In this contribution, we present the theoretical background, assessment of approximations, and results of electronic and transport properties in the framework of density-functional theory. Our implementation considers the analytical strain derivatives (stress tensor) including the contributions that stem from (a) van-der-Waals interactions and (b) the Fock-exchange in hybrid functionals. We validate our approach by investigating the geometric and electronic changes that occur in polyacetylene and anthracene under hydrostatic pressure. We show that the fraction of exact exchange included in the calculations is critical - and non-trivial to choose - for a correct description of these systems. Furthermore, we point out trends for the electrical conductivity under pressure and identify the dominant charge carriers and transport directions.

  6. Electrical Properties of Graphene for Interconnect Applications

    Directory of Open Access Journals (Sweden)

    Antonio Maffucci

    2014-05-01

    Full Text Available A semi-classical electrodynamical model is derived to describe the electrical transport along graphene, based on the modified Boltzmann transport equation. The model is derived in the typical operating conditions predicted for future integrated circuits nano-interconnects, i.e., a low bias condition and an operating frequency up to 1 THz. A generalized non-local dispersive Ohm’s law is derived, which can be regarded as the constitutive equation for the material. The behavior of the electrical conductivity is studied with reference to a 2D case (the infinite graphene layer and a 1D case (the graphene nanoribbons. The modulation effects of the nanoribbons’ size and chirality are highlighted, as well as the spatial dispersion introduced in the 2D case by the dyadic nature of the conductivity.

  7. Characterization of the Muscle Electrical Properties in Low Back Pain Patients by Electrical Impedance Myography

    OpenAIRE

    Congo Tak-Shing Ching; Yueh-Chi Chen; Li-Hua Lu; Hsieh, Peiyuan F; Chin-Sung Hsiao; Tai-Ping Sun; Hsiu-Li Shieh; Kang-Ming Chang

    2013-01-01

    OBJECTIVES: This study aims to investigate the electrical properties of lumbar paraspinal muscles (LPM) of patients with acute lower back pain (LBP) and to study a new approach, namely Electrical Impedance Myography (EIM), for reliable, low-cost, non-invasive, and real-time assessment of muscle-strained acute LBP. DESIGN: Patients with muscle-strained acute LBP (n = 30) are compared to a healthy reference group (n = 30). Electrical properties of LPM are studied. BACKGROUND: EIM is a novel tec...

  8. Developing electrical properties of postnatal mouse lumbar motoneurons

    Directory of Open Access Journals (Sweden)

    Jacques eDurand

    2015-09-01

    Full Text Available We studied the rapid changes in electrical properties of lumbar motoneurons between postnatal days 3 and 9 just before mice weight-bear and walk. The input conductance and rheobase significantly increased up to P8. A negative correlation exists between the input resistance and rheobase. Both parameters are significantly correlated with the total dendritic surface area of motoneurons, the largest motoneurons having the lowest input resistance and the highest rheobase. We classified the motoneurons into three groups according to their discharge firing patterns during current pulse injection (transient, delayed onset, sustained. The delayed onset firing type has the highest rheobase and the fastest action potential whereas the transient firing group has the lowest rheobase and the less mature action potential. We found 32% and 10 % of motoneurons with a transient firing at P3-P5 and P8, respectively. About 20% of motoneurons with delayed onset firing were detected at P8. At P9, all motoneurons exhibit a sustained firing. We defined five groups of motoneurons according to their discharge firing patterns in response to ascending and descending current ramps. In addition to the four classical types, we defined a fifth type called transient for the quasi-absence of discharge during the descending phase of the ramp. This transient type represents about 40% between P3-P5 and tends to disappear with age. Types 1 and 2 (linear and clockwise hysteresis are the most preponderant at P6-P7. Types 3 and 4 (prolonged sustained and counter clockwise hysteresis emerge at P8-P9. The emergence of type 3 and 4 probably depends on the maturation of L type calcium channels in the dendrites of motoneurons. No correlation was found between groups defined by step or triangular ramp of currents with the exception of transient firing patterns. Our data support the idea that a switch in the electrical properties of lumbar motoneurons might exist in the second postnatal week

  9. The Elusive Memristor: Properties of Basic Electrical Circuits

    Science.gov (United States)

    Joglekar, Yogesh N.; Wolf, Stephen J.

    2009-01-01

    We present an introduction to and a tutorial on the properties of the recently discovered ideal circuit element, a memristor. By definition, a memristor M relates the charge "q" and the magnetic flux [phi] in a circuit and complements a resistor R, a capacitor C and an inductor L as an ingredient of ideal electrical circuits. The properties of…

  10. Electric field dependence of junction magnetoresistance in magnetite/semiconductor heterostructure at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Aireddy, H.; Bhaumik, S.; Das, A. K., E-mail: amal@phy.iitkgp.ernet.in [Department of Physics, Indian Institute of Technology, Kharagpur 721 302 (India)

    2015-12-07

    We have fabricated Fe{sub 3}O{sub 4}/p-Si heterojunction using pulsed laser deposition technique and explored its electro-magnetic transport properties. The heterojunction exhibits backward rectifying property at all temperatures, and appraisal of giant junction magnetoresistance (JMR) is observed at room temperature (RT). Conspicuously, the variation and sign change of JMR as a function of electric field is observed at RT. The backward rectifying behavior of the device is ascribed to the highly doped p-type (p{sup ++}) semiconducting nature of Fe{sub 3}O{sub 4}, and the origin of electric field (voltage) dependence of magnetoresistance is explained proposing electronic band diagram of Fe{sub 3}O{sub 4}/SiO{sub 2}/p-Si heterojunction. This interesting result may have importance to integrate Si-based magnetoresistance sources in multifunctional spintronic devices.

  11. Electrical properties of CdS/CdTe heterojunctions

    Science.gov (United States)

    Chu, T. L.; Chu, Shirley S.; Ang, S. T.

    1988-08-01

    The electrical properties of n-CdS/p-CdTe heterojunctions depend strongly on the cleanliness of the interface region. In this work, CdTe films were deposited on CdS/glass substrates by close-spaced sublimation (CSS) under various conditions. The dark current-voltage characteristics of the resulting heterojunctions were measured over a wide temperature range, and the capacitance-voltage characteristics were measured in the dark and under illumination. When the CdS surface is in situ cleaned prior to the deposition of the CdTe film, the current transport across the junction is controlled by a thermally activated process. Tunneling makes an important contribution to the interface recombination at temperatures below room temperature when the in situ cleaning of CdS is not used. The dark capacitance of CdS/CdTe heterojunctions prepared with in situ etching is essentially independent of the reverse bias due to intrinsic interface states. Under white light illumination, the 1/C 2 vs V relation is nearly linear. The CdS/CdTe heterojunctions without in situ cleaning showed different 1/C 2 vs V relations due to higher density of interface states. The in situ cleaning also has pronounced effects on the frequency dependence of dark and illuminated capacitances. Using the in situ cleaning technique, solar cells of about 1 cm2 area have achieved an AM 1.5 (global) efficiency of about 10.5%.

  12. Model dependence of the H2 electric dipole moment

    Science.gov (United States)

    Afnan, I. R.; Gibson, B. F.

    2010-12-01

    Background: Direct measurement of the electric dipole moment (EDM) of the neutron is in the future; measurement of a nuclear EDM may well come first. The deuteron is one nucleus for which exact model calculations are feasible. Purpose: We explore the model dependence of deuteron EDM calculations. Methods: Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variation in the nucleon-nucleon interaction. We write the EDM as the sum of two terms, the first depending on the target wave function with plane-wave intermediate states, and the second depending on intermediate multiple scattering in the 3P1 channel, the latter being sensitive to the off-shell behavior of the 3P1 amplitude. Results: We compare the full calculation with the plane-wave approximation result, examine the tensor force contribution to the model results, and explore the effect of short-range repulsion found in realistic, contemporary potential models of the deuteron. Conclusions: Because one-pion exchange dominates the EDM calculation, separable potential model calculations will provide an adequate description of the H2 EDM until such time as a measurement better than 10% is obtained.

  13. 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...

  14. Model dependence of the deuteron electric dipole moment

    Science.gov (United States)

    Gibson, B. F.; Afnan, I. R.

    2012-09-01

    Direct measurement of the electric dipole moment (EDM) of the neutron lies in the future; measurement of a nuclear EDM may well be obtained first. The deuteron is the one nucleus for which exact model calculations can easily be performed. In this report we explore the model dependence of deuteron EDM calculations. Using a separable potential formulation of the Hamiltonian, we examine the sensitivity of the deuteron EDM to variations in the nucleon-nucleon interaction, including contemporary potential models. We compare the full calculation with the result in the plane-wave approximation, explore the tensor force contribution to the model results, and examine the effects of short range repulsion that characterizes realistic, contemporary potential models of the deuteron. We find that separable potential model calculations will provide an adequate description of the deuteron EDM until such time as a measurement of better than 10% is achieved.

  15. Time- and space-dependent electric response of Ovonic devices

    Science.gov (United States)

    Jacoboni, C.; Piccinini, E.; Brunetti, R.; Rudan, M.

    2017-06-01

    A time- and space-dependent 1D model including the self-consistent solution of the Poisson equation is presented to study the electric response of nanometer Ovonic samples. The model accounts for the main features of the relevant microscopic processes occurring inside the material, and is easily incorporated in commercial device-simulation tools. Numerical results are presented and discussed for Ovonic samples of different lengths and material parameters, and successfully compared to recent optimized experimental results for AgInTeSb. The analysis indicates a very short intrinsic response time of Ovonic devices, of the order of tens of ps and a minimum device length of the order of 5-10 nm, in order to guarantee the device functionality. Tests on the sensitivity of the model on some physical parameters have also been carried out.

  16. Digital laser printing of metal/metal-oxide nano-composites with tunable electrical properties

    Science.gov (United States)

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

    2016-01-01

    We study the electrical properties of aluminum structures printed by the laser forward transfer of molten, femtoliter droplets in air. The resulting printed material is an aluminum/aluminum-oxide nano-composite. By controlling the printing conditions, and thereby the droplet volume, its jetting velocity and duration, it is possible to tune the electrical resistivity to a large extent. The material resistivity depends on the degree of oxidation which takes place during jetting and on the formation of electrical contact points as molten droplets impact the substrate. Evidence for these processes is provided by FIB cross sections of printed structures.

  17. Local electric conductive property of Si nanowire models

    Directory of Open Access Journals (Sweden)

    Yuji Ikeda

    2012-12-01

    Full Text Available Local electric conductive properties of Si nanowire models are investigated by using two local electric conductivity tensors, σ↔ ext (r⃗ and σ↔ int (r⃗, defined in Rigged QED. It is emphasized that σ↔ int (r⃗ is defined as the response of electric current to the actual electric field at a specific point and does not have corresponding macroscopic physical quantity. For the Si nanowire models, there are regions which show complicated response of electric current density to electric field, in particular, opposite and rotational ones. Local conductivities are considered to be available for the study of a negative differential resistance (NDR, which may be related to this opposite response. It is found that σ↔ int (r⃗ shows quite different pattern from σ↔ ext (r⃗, local electric conductivity defined for the external electric field. The effects of impurities are also studied by using the model including a Ge atom, in terms of the local response to electric field. It is found that the difference from the pristine model is found mainly around the Ge atom.

  18. Electrical properties of molecular crystals; Proprietes electriques des cristaux moleculaires

    Energy Technology Data Exchange (ETDEWEB)

    Barraud, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    This literature survey summarizes the electrical properties of molecular crystals: molecular crystal structure, transport and excitation mechanisms of charge-carriers, and differences compared to inorganic semi-conductors. The main results concerning the electrical conductivity of the most-studied molecular crystals are presented, together with the optical and photo-electrical properties of these crystals. Finally the different types of electrical measurements used are reviewed, as well as the limits of each method. (author) [French] Cette etude bibliographique resume les proprietes electriques des cristaux moleculaires: structure des cristaux moleculaires, mecanismes de transport et d'excitation des porteurs de charge et differences avec les semiconducteurs mineraux. Les principaux resultats sur la conductibilite electrique des cristaux moleculaires les plus etudies y sont exposes, ainsi que les proprietes optiques et photoelectriques de ces cristaux. Enfin les differents types de mesures electriques utilisees sont passees en revue ainsi que les limites de chaque methode. (auteur)

  19. Electrical Properties of Carbon Fiber Support Systems

    CERN Document Server

    Cooper, W; Demarteau, M; Fast, J; Hanagaki, K; Johnson, M; Kuykendall, W; Lubatti, H; Matulik, M; Nomerotski, A; Quinn, B; Wang, J

    2005-01-01

    Carbon fiber support structures have become common elements of detector designs for high energy physics experiments. Carbon fiber has many mechanical advantages but it is also characterized by high conductivity, particularly at high frequency, with associated design issues. This paper discusses the elements required for sound electrical performance of silicon detectors employing carbon fiber support elements. Tests on carbon fiber structures are presented indicating that carbon fiber must be regarded as a conductor for the frequency region of 10 to 100 MHz. The general principles of grounding configurations involving carbon fiber structures will be discussed. To illustrate the design requirements, measurements performed with a silicon detector on a carbon fiber support structure at small radius are presented. A grounding scheme employing copper-kapton mesh circuits is described and shown to provide adequate and robust detector performance.

  20. Experimental Studies on Thermal and Electrical Properties of Platinum Nanofilms

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xing; ZHANG Qing-Guang; CAO Bing-Yang; FUJII Motoo; TAKAHASHI Koji; IKUTA Tatsuya

    2006-01-01

    @@ We experimentally studied the in-plane thermal and electrical properties of a suspended platinum nanofilm in thickness of 15 nm. The measured results show that the in-plane thermal conductivity, the electrical conductivity and the resistance-temperature coefficient of the studied nanofilm are much less than those of the bulk material,while the Lorenz number is greater than the bulk value.

  1. Solvent dependent photophysical properties of dimethoxy curcumin

    Science.gov (United States)

    Barik, Atanu; Indira Priyadarsini, K.

    2013-03-01

    Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (Δf), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9 D. Fluorescence quantum yield (ϕf) and fluorescence lifetime (τf) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ϕf increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.

  2. Electric Field Structures in Thin Films: Formation and Properties

    DEFF Research Database (Denmark)

    Cassidy, Andrew; Plekan, Oksana; Balog, Richard

    2014-01-01

    by combining layers of different spontelectric materials. This is demonstrated using the spontelectric materials nitrous oxide, toluene, isoprene, isopentane, and CF2Cl2. These yield a variety of tailored electric field structures, with individual layers harboring fields between 107 and 108 V/m. Fields may......A newly discovered class of molecular materials, so-called “spontelectrics”, display spontaneous electric fields. Here we show that the novel properties of spontelectrics can be used to create composite spontelectrics, illustrating how electric fields in solid films may be structured on the nanoscale...

  3. Basic properties of electrical field coupling between neurons: an analytical approach.

    Science.gov (United States)

    Costalat, Robert; Chauvet, Gilbert

    2008-06-01

    The basic properties of the electrical field coupling between two parallel neurons, with linear electrical properties of the membranes, are investigated using a mathematical model-based on Laplace transform and matrix algebra, assuming that the system is unidimensional. This approach is extended to a ramified dendritic tree, and to a set of parallel neurons a subset of which is synaptically activated. We show that the electrical field effect is governed by certain geometrical and electrophysiological parameters, the most important being a coupling coefficient k, which depends on the extra- and intracellular resistivity, as well as the extracellular volume fraction. These results support the hypothesis that electrical field effects play an important role in the regions of the brain where neurons are densely packed, even in the absence of, or before, cell firing.

  4. Structural, morphology and electrical properties of layered copper selenide thin film

    Science.gov (United States)

    Ying Chyi Liew, J.; Talib, Zainal; Mahmood, W.; Yunus, M.; Zainal, Zulkarnain; Halim, Shaari; Moksin, Mohd; Yusoff, Wan; Pah Lim, K.

    2009-06-01

    Thin films of copper selenide (CuSe) were physically deposited layer-by-layer up to 5 layers using thermal evaporation technique onto a glass substrate. Various film properties, including the thickness, structure, morphology, surface roughness, average grain size and electrical conductivity are studied and discussed. These properties are characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ellipsometer and 4 point probe at room temperature. The dependence of electrical conductivity, surface roughness, and average grain size on number of layers deposited is discussed.

  5. Effects of sodium on electrical properties in Cu2ZnSnS4 single crystal

    Science.gov (United States)

    Nagaoka, Akira; Miyake, Hideto; Taniyama, Tomoyasu; Kakimoto, Koichi; Nose, Yoshitaro; Scarpulla, Michael A.; Yoshino, Kenji

    2014-04-01

    We have studied the effect of sodium on the electrical properties of Cu2ZnSnS4 (CZTS) single crystal by using temperature dependence of Hall effect measurement. The sodium substitution on the cation site in CZTS is observed from the increasing of unit-cell size by powder X-ray diffraction. Sodium increases the effective hole concentration and makes the thermal activation energy smaller. The degree of compensation decreases with sodium incorporation, thus the hole mobility is enhanced. We revealed that sodium is important dopant in CZTS to control the electrical properties.

  6. Surface and size effects on the electrical properties of Cu nanowires

    Science.gov (United States)

    Huang, Qiaojian; Lilley, Carmen M.; Bode, Matthias; Divan, Ralu

    2008-07-01

    Copper nanowires were patterned with e-beam lithography and fabricated with a copper film deposited by e-beam evaporation. Various electrical properties of these nanowires (including resistivity, temperature coefficient of resistance, and failure current density) were characterized. It was experimentally found that surface and size have apparent effects on the electrical properties. Smaller values for the temperature coefficient of resistance and higher failure current density were found for Cu nanowires with decreasing wire width. The experimental finding of width dependent failure current density also agrees with finding for theoretical heat transfer of the nanowire and substrate system as calculated with the finite element method.

  7. Nanoscale electrical properties of epitaxial Cu3Ge film

    Science.gov (United States)

    Wu, Fan; Cai, Wei; Gao, Jia; Loo, Yueh-Lin; Yao, Nan

    2016-07-01

    Cu3Ge has been pursued as next-generation interconnection/contact material due to its high thermal stability, low bulk resistivity and diffusion barrier property. Improvements in electrical performance and structure of Cu3Ge have attracted great attention in the past decades. Despite the remarkable progress in Cu3Ge fabrication on various substrates by different deposition methods, polycrystalline films with excess Ge were frequently obtained. Moreover, the characterization of nanoscale electrical properties remains challenging. Here we show the fabrication of epitaxial Cu3Ge thin film and its nanoscale electrical properties, which are directly correlated with localized film microstructures and supported by HRTEM observations. The average resistivity and work function of epitaxial Cu3Ge thin film are measured to be 6 ± 1 μΩ cm and ~4.47 ± 0.02 eV respectively, qualifying it as a good alternative to Cu.

  8. Nanoscale electrical properties of epitaxial Cu3Ge film

    Science.gov (United States)

    Wu, Fan; Cai, Wei; Gao, Jia; Loo, Yueh-Lin; Yao, Nan

    2016-01-01

    Cu3Ge has been pursued as next-generation interconnection/contact material due to its high thermal stability, low bulk resistivity and diffusion barrier property. Improvements in electrical performance and structure of Cu3Ge have attracted great attention in the past decades. Despite the remarkable progress in Cu3Ge fabrication on various substrates by different deposition methods, polycrystalline films with excess Ge were frequently obtained. Moreover, the characterization of nanoscale electrical properties remains challenging. Here we show the fabrication of epitaxial Cu3Ge thin film and its nanoscale electrical properties, which are directly correlated with localized film microstructures and supported by HRTEM observations. The average resistivity and work function of epitaxial Cu3Ge thin film are measured to be 6 ± 1 μΩ cm and ~4.47 ± 0.02 eV respectively, qualifying it as a good alternative to Cu. PMID:27363582

  9. The Electrical and Dynamical Properties of Biomembranes

    DEFF Research Database (Denmark)

    Mosgaard, Lars Dalskov

    of a more general treatment. This purely thermodynamical treatment only describes the equilibrium properties of the membrane, however biological processes are of course dynamical in nature. A clear understanding of the dynamical behavior of lipid membranes is therefore essential when we aim at unraveling...... electrophysiological methods such as \\jump experiments" and impedance spectroscopy performed on lipid membranes. By doing so we observe that a number of non-linear phenomena previously thought to be associated with the presence of proteins embedded in the membrane can just as well be produced by a 'pure' lipid...

  10. Temperature dependent electrical characterization of thin film Cu2ZnSnSe4 solar cells

    Science.gov (United States)

    Kask, E.; Krustok, J.; Giraldo, S.; Neuschitzer, M.; López-Marino, S.; Saucedo, E.

    2016-03-01

    Impedance spectroscopy (IS) and current-voltage characteristics measurements were applied to study properties of a Cu2ZnSnSe4 (CZTSe) thin film solar cell. IS measurements were done in the frequency range 20 Hz to 10 MHz. The measurement temperature was varied from 10 K to 325 K with a step ▵T  =  5 K. Temperature dependence of V oc revealed an activation energy of 962 meV, which is in the vicinity of the band gap energy of CZTSe and hence the dominating recombination mechanism in this solar cell is bulk recombination. Different temperature ranges, where electrical properties change, were found. Interface states at grain boundaries with different properties were revealed to play an important role in impedance measurements. These states can be described by introducing a constant phase element in the equivalent circuit.

  11. Characterization of electrical and optical properties of silicon based materials

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Guobin

    2009-12-04

    In this work, the electrical and luminescence properties of a series of silicon based materials used for photovoltaics, microelectronics and nanoelectronics have been investigated by means of electron beam induced current (EBIC), cathodoluminescence (CL), photoluminescence (PL) and electroluminescence (EL) methods. Photovoltaic materials produced by block casting have been investigated by EBIC on wafers sliced from different parts of the ingot. Various solar cell processings have been compared in parallel wafers by means of EBIC collection efficiency measurements and contrast-temperature C(T) behaviors of the extended defects, i. e. dislocations and grain boundaries (GBs). It was found that the solar cell processing with phosphorus diffusion gettering (PDG) followed with a SiN firing greatly reduces the recombination activity of extended defects at room temperature, and improves the bulk property simultaneously. A remaining activity of the dislocations indicates the limitation of the PDG at extended defects. Abnormal behavior of the dislocation activity after certain solar cell processes was also observed in the region with high dislocation density, the dislocations are activated after certain solar cell processings. In order to evaluate the properties of a thin polycrystalline silicon layer prepared by Al-induced layer exchange (Alile) technique, epitaxially layer grown on silicon substrate with different orientations was used as a model system to investigate the impact by the process temperature and the substrates. EBIC energy dependent collection efficiency measurements reveal an improvement of the epilayer quality with increasing substrate temperature during the growth from 450 C to 650 C, and a decrease of epilayer quality at 700 C. PL measurements on the epitaxially grown Si layer on silicon substrates revealed no characteristic dislocation-related luminescence (DRL) lines at room temperature and 77 K, while in the samples prepared by Alile process, intense

  12. Electrical properties of donors in gallium phosphide

    Energy Technology Data Exchange (ETDEWEB)

    Poedoer, B. (Hungarian Academy of Sciences, Budapest. Research Lab. for Inorganic Chemistry); Pfeiffer, J.; Csontos, L.; Nador, N. (Hungarian Academy of Sciences, Budapest. Research Inst. for Technical Physics); Deak, F. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Atomfizikai Tanszek)

    1983-04-16

    The thermal ionization energies of S, Te, and Si donors in GaP and their dependences on impurity concentration are determined from an anlysis of Hall effect data. An ellipsoidal six-valley model is used incorporating the effects of valley-orbit splitting of the ground state of the P-site donors. A careful characterization of the samples ensures that results are obtained on samples containing only one type of dominant donor. The thermal ionization energies of the above donors extrapolated to infinite dilution are (105.0 +- 5.7), (94.1 +- 2.6), and (83.5 +- 1.7) meV, respectively. The valley-orbit splitting energies of S and Te donors are also obtained, amounting to (34 +- 9) and (23.5 +- 9) meV, respectively.

  13. Polymer composites with graphene nanofillers: electrical properties and applications.

    Science.gov (United States)

    Tjong, Sie Chin

    2014-02-01

    Graphene with extraordinary high elastic modulus and excellent electrical conductivity has good prospects for use as the filler material for fabricating novel polymer composites designed for electrostatic discharge and EMI shielding protection, field emission, gas sensor, and fuel cell applications. Large amounts of graphene oxide (GO) can be obtained by wet chemical oxidation of graphite into a mixture of concentrated sulfuric acid, sodium nitrate and potassium permanganate. Accordingly, carbon atoms in the basal plane and edges of GO are decorated with oxygenated functional groups, forming an electrical insulator. To restore electrical conductivity, chemical reduction or thermal annealing is needed to eliminate oxygenated groups of GO. However, such treatments induce internal defects and remove oxygenated atoms of GO partially. The remnant-oxygenated groups affect electrical conductivity of graphene greatly. Nevertheless, reduced graphene oxide and thermally reduced graphene oxide are sufficiently conductive to form polymer nanocomposites at very low percolation threshold. This review provides the fundamentals and state-of-the-art developments in the fabrication methods and electrical property characterizations as well as the applications of novel graphene/polymer nanocomposites. Particular attention is paid to their processing-structural-electrical property relationships.

  14. Optical and electrical properties of nickel xanthate thin films

    Indian Academy of Sciences (India)

    İ A Kariper; T Özpozan

    2014-05-01

    Nickel xanthate thin films (NXTF) were successfully deposited by chemical bath deposition, on to amorphous glass substrates, as well as on - and -silicon, indium tin oxide and poly(methyl methacrylate). The structure of the films was analysed by X-ray diffraction (XRD), far-infrared spectrum (FIR), mid-infrared (MIR) spectrum, nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). These films were investigated from their structural, optical and electrical properties point of view. Uniform distribution of grains was clearly observed from the photographs taken by scanning electron microscope (SEM). The higher transmittance was about 50–60% after optimizing the parameters of deposition time and temperature (4 h, 50 °C). The optical bandgap of the NXTF was graphically estimated as 3.90–3.96 eV. The resistivity of the films was calculated as 62.6–90.7 .cm on commercial glass depending on the film thickness and 62.2–74.5 .cm on the other substrates. The MIR and FIR spectra of the films conformed to the literature and their solid powder forms. The expected peaks of nickel xanthate were observed in NMR analysis on glass. The films were dipped into chloroform as organic solvent and were analysed by NMR.

  15. Electrical properties of iron doped apatite-type lanthanum silicates

    Institute of Scientific and Technical Information of China (English)

    SHI Qingle; ZHANG Hua

    2012-01-01

    The effect of Fe doping on the electrical properties of lanthanum silicates was investigated.The apatite-type lanthanum silicates La10Si6-xFexO27-x/2 (x=0.2,0.4,0.6,0.8,1.0) were synthesized via sol-gel process.The unit cell volume increased with Fe doping because the ionic radius of Fe3+ ion is larger than that of Si4+ ion.The conductivities of La10Si6-xFexO27 x/2 first increased and then decreased with the increasing of Fe content.The increase of the conductivity might be attributed to the distortion of the cell lattice,which assisted the migration of the interstitial oxygen ions.The decrease of the conductivity might be caused by the lower concentration of interstitial oxygen ions.The optimum Fe doping content in lanthanum silicates was 0.6.La10Si5.4Fe0.6O26.7 exhibited the highest ionic conductivity of 2.712× 10-2 S/cm at 800 ℃.The dependence of conductivity on oxygen partial pressure p(O2) suggested that the conductivity of La10Si6-xFexO27-x/2 was mainly contributed by ionic conductivity.

  16. Electrical properties of oxygen ion-implanted InP

    Science.gov (United States)

    He, L.; Anderson, W. A.

    1992-10-01

    The effect of oxygen ion implantation on defect levels and the electrical properties of undoped InP ( n-type) and Sn-doped InP have been investigated as a function of postimplant annealing at temperatures of 300 and 400° C. The surface interruption by ion bombardment was studied by a non-invasive optical technique—photoreflectance (PR) spectroscopy. Current-voltage (I-V) characterization and deep level transient spectros-copy (DLTS) were carried out. The free carrier compensation mechanism was studied from the microstructure behavior of defect levels associated with O+ implantation. Free carriers may be trapped in both residual and ion-bombardment-induced defect sites. Rapid thermal annealing (RTA) performed at different temperatures showed that if residual traps were removed by annealing, the compensation efficiency will be enhanced. Post-implant RTA treatment showed that at the higher temperature (400°C), trapped carriers may be re-excited, resulting in a weakened compensation. Comparing the results of undoped and Sn-doped InP indicated that the carrier compensation effect is substrate doping dependent.

  17. Mapping the electrical properties of large-area graphene

    DEFF Research Database (Denmark)

    Bøggild, Peter; Mackenzie, David; Whelan, Patrick Rebsdorf

    2017-01-01

    The significant progress in terms of fabricating large-area graphene films for transparent electrodes, barriers, electronics, telecommunication and other applications has not yet been accompanied by efficient methods for characterizing the electrical properties of large-area graphene. While...... in the early prototyping as well as research and development phases, electrical test devices created by conventional lithography have provided adequate insights, this approach is becoming increasingly problematic due to complications such as irreversible damage to the original graphene film, contamination......, and a high measurement effort per device. In this topical review, we provide a comprehensive overview of the issues that need to be addressed by any large-area characterisation method for electrical key performance indicators, with emphasis on electrical uniformity and on how this can be used to provide...

  18. In-plane orientation and composition dependences of crystal structure and electrical properties of {100}-oriented Pb(Zr,Ti)O3 films grown on (100) Si substrates by metal organic chemical vapor deposition

    Science.gov (United States)

    Okamoto, Shoji; Sankara Rama Krishnan, P. S.; Okamoto, Satoshi; Yokoyama, Shintaro; Akiyama, Kensuke; Funakubo, Hiroshi

    2017-10-01

    In-plane orientation-controlled Pb(Zr x ,Ti1‑ x )O3 (PZT) films with a thickness of approximately 2 µm and a Zr/(Zr + Ti) ratio of 0.39–0.65 were grown on (100) Si substrates by pulsed metal–organic chemical vapor deposition (MOCVD). In-plane-oriented epitaxial PZT films and in-plane random fiber-textured PZT films with {100} out-of-plane orientation were grown on (100)c SrRuO3//(100)c LaNiO3//(100) CeO2//(100) YSZ//(100) Si and (100)c SrRuO3/(100)c LaNiO3/(111) Pt/TiO2/SiO2/(100) Si substrates, respectively. The effects of Zr/(Zr + Ti) ratio and in-plane orientation on the crystal structure, dielectric, ferroelectric, and piezoelectric properties of the films were systematically investigated. The X-ray diffraction measurement showed that the epitaxial PZT films had a higher volume fraction of (100) orientation than the fiber-textured PZT films in the tetragonal Zr/(Zr + Ti) ratio region. A large difference was not detected between the epitaxial films and the fiber-textured films for Zr/(Zr + Ti) ratio dependence of the dielectric constant, and remanent polarization. However, in the rhombohedral phase region [Zr/(Zr + Ti) = 0.65], coercive field was found to be 1.5-fold different between the epitaxial and fiber-textured PZT films. The maximum field-induced strains measured at 0–100 kV/cm by scanning atomic force microscopy were obtained at approximately Zr/(Zr + Ti) = 0.50 and were about 0.5 and 0.3% for the epitaxial and fiber-textured PZT films, respectively.

  19. Composite Materials with Magnetically Aligned Carbon Nanoparticles Having Enhanced Electrical Properties and Methods of Preparation

    Science.gov (United States)

    Hong, Haiping (Inventor); Peterson, G.P. (Bud) (Inventor); Salem, David R. (Inventor)

    2016-01-01

    Magnetically aligned carbon nanoparticle composites have enhanced electrical properties. The composites comprise carbon nanoparticles, a host material, magnetically sensitive nanoparticles and a surfactant. In addition to enhanced electrical properties, the composites can have enhanced mechanical and thermal properties.

  20. Preparation and electrical properties of oil-based magnetic fluids

    Science.gov (United States)

    Sartoratto, P. P. C.; Neto, A. V. S.; Lima, E. C. D.; Rodrigues de Sá, A. L. C.; Morais, P. C.

    2005-05-01

    This paper describes an improvement in the preparation of magnetic fluids for electrical transformers. The samples are based on surface-coated maghemite nanoparticles dispersed in transformer insulating oil. Colloidal stability at 90°C was higher for oleate-grafted maghemite-based magnetic fluid, whereas decanoate and dodecanoate-grafted samples were very unstable. Electrical properties were evaluated for samples containing 0.80%-0.0040% maghemite volume fractions. Relative permittivity varied from 8.8 to 2.1 and the minimum value of the loss factor was 12% for the most diluted sample. The resistivity falls in the range of 0.7-2.5×1010Ωm, whereas the ac dielectric strength varied from 70to79kV. These physical characteristics reveal remarkable step forward in the properties of the magnetic fluid samples and may result in better operation of electrical transformers.

  1. Electrical Properties of the ZnO/Si Heterostructure

    Institute of Scientific and Technical Information of China (English)

    刘磁辉; 林碧霞; 朱俊杰; 付竹西; 彭聪; 杨震; 陈宇林

    2001-01-01

    The electrical properties of a type of semiconductor heterostructure fabricated by depositing zinc oxide film on a silicon substrate are investigated. The I - V, I - T curves, and deep level transient spectra are measured. From these results, we acquire the information of the characteristics of the junction, and compute some energy levelsof the samples.

  2. Probe for testing electrical properties of a test sample

    DEFF Research Database (Denmark)

    2012-01-01

    A probe for testing electrical properties of test samples includes a body having a probe arm defining proximal and distal ends, the probe arm extending from the body at the proximal end of the probe arm, whereby a first axis is defined by the proximal and the distal ends. The probe arm defines...

  3. Optical and electrical properties of bi-layers organic devices

    Science.gov (United States)

    Trad, Hager; Rouis, Ahlem; Davenas, Jöel; Majdoub, Mustapha

    2014-10-01

    The influence of interfacial charges on the device characteristics of bi-layers structure LEDs with poly[5-methoxy-2-octyloxy-1,4-phenylenevinylene] (MO-PPV) as active polymer layer is investigated. The concept to improve device performance is presented using: a diacetate cellulose (DAC) and a new synthetized 5-{2-(2-chloroethoxy)ethoxy}-2-{(E)-(2-pyridyl)azo}phenol (PDEG) components. The DAC and mixed (DAC+PDEG) layers were inserted between indium tin oxide (ITO) and MO-PPV polymer. The optical properties (UV-Vis) of MO-PPV, PDEG and mixed (DAC+PDEG) in solutions were studied and compared to those on thin films. Detailed current-voltage measurements of the bi-layers devices showed improvements of the threshold voltage (Vth) of the ITO/(DAC+PDEG)/MO-PPV/Al device attributed to the enhancement of carriers injection and transport resulted from the modified electrode structures. Conduction mechanisms of structure LEDs were matched with space-charge-limited current (SCLC) one. The impedance spectra for all devices can be discussed in terms of an equivalent circuit model designed as a parallel resistor Rp and capacitor Cp network in series with resistor Rs. The ITO/(DAC+PDEG)/MO-PPV/Al device showed the lowest impedance attributed to the removal of contaminants and to changes in the work function of ITO. The frequency-dependent electrical properties of the ITO/(DAC+PDEG)/MO-PPV/Al structure is analyzed by impedance spectroscopy as function of bias. We have extracted numerical values of the equivalent circuit model parameters by fitting experimental data. Their evolution with bias voltages has shown that the SCLC mechanism is characterized by an exponential trap distribution.

  4. Irradiation imposed degradation of the mechanical and electrical properties of electrical insulation for future accelerator magnets

    Energy Technology Data Exchange (ETDEWEB)

    Polinski, J.; Chorowski, M.; Bogdan, P.; Strychalski, M. [Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland); Rijk, G. de [European Organization for Nuclear Research CERN, 1211 Geneva (Switzerland)

    2014-01-27

    Future accelerators will make extensive use of superconductors made of Nb{sub 3}Sn, which allows higher magnetic fields than NbTi. However, the wind-and-react technology of Nb{sub 3}Sn superconducting magnet production makes polyimide Kapton® non applicable for the coils' electrical insulation. A Nb{sub 3}Sn technology compatible insulation material should be characterized by high radiation resistivity, good thermal conductivity, and excellent mechanical properties. Candidate materials for the electrical insulation of future accelerator's magnet coils have to be radiation certified with respect to potential degradation of their electrical, thermal, and mechanical properties. This contribution presents procedures and results of tests of the electrical and mechanical properties of DGEBA epoxy + D400 hardener, which is one of the candidates for the electrical insulation of future magnets. Two test sample types have been used to determine the material degradation due to irradiation: a untreated one (unirradiated) and irradiated at 77 K with 11 kGy/min intense, 4MeV energy electrons beam to a total dose of 50 MGy.

  5. Irradiation imposed degradation of the mechanical and electrical properties of electrical insulation for future accelerator magnets

    Science.gov (United States)

    Polinski, J.; Chorowski, M.; Bogdan, P.; Strychalski, M.; de Rijk, G.

    2014-01-01

    Future accelerators will make extensive use of superconductors made of Nb3Sn, which allows higher magnetic fields than NbTi. However, the wind-and-react technology of Nb3Sn superconducting magnet production makes polyimide Kapton® non applicable for the coils' electrical insulation. A Nb3Sn technology compatible insulation material should be characterized by high radiation resistivity, good thermal conductivity, and excellent mechanical properties. Candidate materials for the electrical insulation of future accelerator's magnet coils have to be radiation certified with respect to potential degradation of their electrical, thermal, and mechanical properties. This contribution presents procedures and results of tests of the electrical and mechanical properties of DGEBA epoxy + D400 hardener, which is one of the candidates for the electrical insulation of future magnets. Two test sample types have been used to determine the material degradation due to irradiation: a untreated one (unirradiated) and irradiated at 77 K with 11 kGy/min intense, 4MeV energy electrons beam to a total dose of 50 MGy.

  6. General Relationship between Field Electrical Resistivity Value (ERV and Basic Geotechnical Properties (BGP

    Directory of Open Access Journals (Sweden)

    Mohd Hazreek Zainal Abidin

    2014-09-01

    Full Text Available Electrical resistivity technique is a popular alternative method used in geotechnical soil investigations. Most past applications have been particularly in the area of subsurface ground investigations such as to locate boulder, bedrock, water table, etc. Traditionally, this method was performed by a geophysicist expert for data acquisition, processing and interpretation. The final outcome from the electrical resistivity technique was an anomaly image which used to describe and conclude the particular soil condition measured. The anomalies highlighted uncertainties on the nature of soil that was often variable and depended on each particular site condition that gave a site dependent soil electrical resistivity value (ERV. Hence, this study demonstrates a relationship between ERV (ρ and some of the basic geotechnical properties (BGP such as soil moisture content (w, grain size of geomaterial (CS or FS, density (ρbulk and ρdry, porosity (η, void ratio (e and Atterberg limit (AL. Different soil samples were collected and tested under field and laboratory conditions to determine basic geotechnical properties immediately after the field electrical resistivity method was performed. It was found that the electrical resistivity value was different for number of soils tested and was relatively subjective to variations in the geotechnical properties. In other words, electrical resistivity value was greatly influenced by the geotechnical properties as the ERV was higher due to the lower moisture content, void ratio and porosity with a higher value of soil density and vice versa. The relationship of ERV and BGP can be described by ρ α 1/w, ρ α CS, ρ α 1/FS, ρ α ρbulk/dry and ρ α 1/AL. Hence, it was shown that behaviour of ERV was significantly influenced by the variation of basic soil properties and thus applicable to support and enhance the conventional stand alone anomaly outcome which is traditionally used for interpretation purposes.

  7. Topological Nanocolloids with Facile Electric Switching of Plasmonic Properties

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Ye; Smalyukh, Ivan I.

    2015-12-01

    Combining topology and plasmonics paradigms in nanocolloidal systems may enable new means of pre-engineering desired composite material properties. Here we design and realize orientationally ordered assemblies of noble metal nanoparticles with genus-one topology and unusual long-range ordering mediated by their interactions with the surrounding nematic fluid host. Facile electric switching of these composites is reminiscent of that of pristine liquid crystals (LCs), but provides a means of reconfiguring the nanoparticle assembly and thus also the ensuing composite medium's optical properties. Our findings may lead to formation of new molecular-colloidal soft matter phases with unusual optical properties, as well as optical metamaterials.

  8. Influence of cadmium sulfide nanoparticles on structural and electrical properties of polyvinyl alcohol films

    Directory of Open Access Journals (Sweden)

    J. Koteswararao

    2016-11-01

    Full Text Available Cadmium sulfide (CdS nanoparticles have been synthesized by hydrothermal method and dispersed in poly vinyl alcohol (PVA matrix in varying amounts by weight. Subsequently, PVA/CdS nanocomposites have been synthesized with the objective of investigating the effect of CdS nanoparticles on structural and electrical properties of PVA films. Structural properties were analyzed by Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD and scanning electron microscopy (SEM techniques. Differential scanning calorimetry (DSC was used to investigate thermal properties of PVA/CdS nanocomposites. Electrical properties were measured by using high frequency LCR meter and were found to be strongly dependent on frequency and nano CdS content. Dielectric constant decreased with increase in frequency and with increase in nanofiller concentration. AC conductivity and dielectric loss increased with frequency and decreased with increase in nano CdS content.

  9. Synthesis, characterization and electrical properties of dihalogenated polyanilines

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, F.R.; Sanchez, C.O.; del Valle, M.A.; Tagle, L.H. [Universidad Catolica de Chile, Santiago (Chile). Fac. of Chem.; Bernede, J.C.; Tregouet, Y. [Laboratoire de Physique des Materiaux pour l`Electronique, Faculte des Sciences et des Techniques de Nantes, 2 rue de la Houssiniere, F-44072, Nantes, Cedex 02 (France)

    1998-01-30

    Poly(2,5-dichloroaniline), poly(2,3-dichloroaniline), poly(3,5-dichloroaniline), poly(2,5-dibromoaniline) and poly(2,6-dibromoaniline) have been synthesized from dihaloanilines in protic and aprotic media with different oxidizing agents, such as copper perchlorate, potassium dichromate and potassium permanganate. Each polymer is characterized by elemental analysis, IR and UV-Vis spectroscopy, scanning electron microscopy (SEM) and conductivity measurements. To obtain the doped polymers, they are treated with inorganic acids and then their electric properties determined. The use of different oxidants allows the obtention of polymers with different redox states which, in some cases, present semiconducting properties and are soluble in methanol and acetone. For the sake of comparison of the electrical and structural properties of the new polymers, polyaniline (PANI) has also been synthesized in a manner analogous to the poly(dihaloanilines). (orig.) 40 refs.

  10. Electric field effect on the second-order nonlinear optical properties in semiparabolic quantum wells

    Science.gov (United States)

    Yuan, Jian-Hui; Chen, Ni; Zhang, Yan; Mo, Hua; Zhang, Zhi-Hai

    2016-03-01

    Electric field effect on the second-order nonlinear optical properties in semiparabolic quantum wells are studied theoretically. Both the second-harmonic generation susceptibility and nonlinear optical rectification depend dramatically on the direction and the strength of the electric field. Numerical results show that both the second-harmonic generation susceptibility and nonlinear optical rectification are always weakened as the electric field increases where the direction of the electric field is along the growth direction of the quantum wells, which is in contrast to the conventional case. However, the second-harmonic generation susceptibility is weakened, but the nonlinear optical rectification is strengthened as the electric field increases where the direction of the electric field is against the growth direction of the quantum wells. Also it is the blue (or red) shift of the resonance that is induced by increasing of the electric field when the direction of the electric field is along (or against) the growth direction of the quantum wells. Finally, the resonant peak and its corresponding to the resonant energy are also taken into account.

  11. Enhancement of electrical properties of polyimide films by plasma treatment

    Science.gov (United States)

    Meddeb, A. Barhoumi; Ounaies, Z.; Lanagan, M.

    2016-04-01

    In this study, the effect of oxygen plasma treatment on the electrical and surface properties of polyimide, Kapton HN, film is investigated. The plasma treatment led to an increase in the oxygen presence on the polyimide surface and a marked surface hydrophilicity. The plasma treatment led to an increase in the dielectric breakdown and Weibull modulus as well as a remarkable reduction in the scatter of all electrical measurements. There is a significant reduction in the high field/high temperature leakage current after plasma treatment. These findings have important implications in the development and improvement of dielectric polymer capacitors.

  12. Mechanical and electrical properties of polycarbonate nanotube buckypaper composite sheets

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Giang T; Park, Young-Bin; Wang Shiren; Liang Zhiyong; Wang Ben; Zhang, Chuck [High-Performance Materials Institute (HPMI), Department of Industrial and Manufacturing Engineering, Florida A and M University, Florida State University College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Funchess, Percy; Kramer, Leslie [Lockheed Martin Missiles and Fire Control-Orlando, Orlando, FL 32819-8907 (United States)], E-mail: gte640q@yahoo.com

    2008-08-13

    The thermogravimetric, mechanical, and electrical properties of composite sheets produced by infiltrating single-wall carbon nanotube films (also known as 'buckypapers') with polycarbonate solution were characterized. The composite sheets showed improved stiffness and toughness, while the electrical conductivity decreased, as compared to a neat buckypaper. In addition, polycarbonate/buckypaper composite sheets showed higher resistance to handling and processing damages. Experimental results suggest the viability of the infiltration process as a means to toughen buckypapers and to fabricate polymer/carbon nanotube composites having high nanotube concentration and controlled nanotube structure.

  13. Characterization of electrical properties of resistance welding machines

    Institute of Scientific and Technical Information of China (English)

    Wu Pei; Shao Yingli; Wenqi Zhang; Niels Bay

    2008-01-01

    Due to the individual electrical and mechanical characteristics of resistance welding machines, choice of the right machine and welding parameters for an optimized production is often difficult. This is especially the case in projection welding of complex joints. In this paper, a new approach of characterizing the electrical properties of AC resistance welding machines is presented, involving testing and mathematical modelling of the weld current, the firing angle and the conduction angle of silicon controlled rectifiers with the aid of a series of proof resistances. The model predicts the weld current and the conduction angle (or heat setting) at each set current, when the workpiece resistance is given.

  14. Nonlinear electrical properties of Si three-terminal junction devices

    DEFF Research Database (Denmark)

    Fantao, Meng; Jie, Sun; Graczyk, Mariusz

    2010-01-01

    This letter reports on the realization and characterization of silicon three-terminal junction devices made in a silicon-on-insulator wafer. Room temperature electrical measurements show that the fabricated devices exhibit pronounced nonlinear electrical properties inherent to ballistic electron...... transport in a three-terminal ballistic junction (TBJ) device. The results show that room temperature functional TBJ devices can be realized in a semiconductor material other than high-mobility III-V semiconductor heterostructures and provide a simple design principle for compact silicon devices...

  15. Magnetic and electrical properties of amorphous Fe-Cr-P-C-Si

    Science.gov (United States)

    Sayouri, S.; Berraho, R.; Moustaide, A.; Benbachir, K.; Kaal, A.; Tlemçani, M.; Berrada, A.

    2003-03-01

    Magnetic and electrical properties of melt-spun amorphous Fe 100- y- zCr y(PCSi) z alloys, 4⩽ y⩽11, 19⩽ z⩽22, have been investigated. The magnetic moment, μCr, of Cr has been estimated and the magnetic coupling constants, JFe-Fe, JFe-Cr and JCr-Cr, between Fe-Fe, Fe-Cr, and Cr-Cr atoms respectively, have been evaluated using the molecular field theory of two-sublattice model. Temperature dependence of electrical resistivity of these amorphous alloys was also studied. The electrical resistivity was measured between 170 and 330 K. The alloys studied exhibit a resistivity minimum at a relatively high temperature. The temperature of resistivity minimum, Tmin, increases with increasing Cr content. The effect of Cr addition in these compounds is compared with that of Co and Ni addition on the electrical resistivity on Fe-based alloys.

  16. Electrical and thermoelectric properties of different compositions of Ge-Se-In thin films

    Science.gov (United States)

    Aly, K. A.; Dahshan, A.; Abbady, Gh.; Saddeek, Y.

    2016-09-01

    The effect of temperature in the range of 300-450 K and the indium content on the electrical and thermoelectric properties of Ge20Se80-xInx (0.0≤x≤24 at%) chalcogenide glassy thin films have been studied. From dc electrical and thermoelectric measurements, it was observed that the activation energies for electrical conductivity (ΔE) and for thermoelectric (ΔEs) decrease while the conductivity (σ) and Seebeck coefficient (S) increase upon introducing In into the Ge-Se glasses. In contrast to the behavior obtained with Bi or Pb doping, In incorporated in Ge-Se does not lead to a p-to n-type conduction inversion. The power factor (P) which is strongly depends on both of the Seebeck coefficient and the electrical conductivity. According to the obtained results, the Ge20Se80-xInx films can be considered potential candidates for incurring high action thermoelectric materials.

  17. A Percolation Study of Wettability Effect on the Electrical Properties of Reservoir Rocks

    DEFF Research Database (Denmark)

    Zhou, Dengen; Arbabi, Sepehr; Stenby, Erling Halfdan

    1997-01-01

    Measurements of the electrical resistivity of oil reservoirs are commonly used to estimate other properties of reservoirs, such as porosity and hydrocarbon reserves. However, the interpretation of the measurements is based on empirical correlations, because the underlying mechanisms that control...... the electrical properties of oil bearing rocks have not been well understood. In this paper, we employ percolation concepts to investigate the effect of wettability on the electrical conductivity of a reservoir formation. A three-dimensional simple cubic network is used to represent an ideal reservoir formation...... behavior of reservoir resistivities of different wettabilities. It demonstrates that the resistivity index depends on saturation history and wettability. For strongly oil-wet systems, significant hysteresis is expected, while there is little hysteresis for strongly water-wet systems, and some hysteresis...

  18. Electrical properties of ZnO varistors prepared by direct mixing of constituent phases

    Directory of Open Access Journals (Sweden)

    Žunić M.

    2006-01-01

    Full Text Available Varistor samples containing different amounts of constituent phases were prepared by direct mixing of constituent phases. Detailed electrical characterization was performed to explain the influence of minor phases (spinel and intergranular phases on overall properties. Characterization included investigation of the non-linear coefficients (α, breakdown electric field (EB, leakage currents (JL, grain boundary barrier hight (ΦB and constant β from current-voltage characteristics, as well as calculation of activation energies for conduction (EA from ac impedance spectroscopy in the temperature interval 30-410°C. Varistors sintered at 1100 °C for 1 h showed pronounced differences in electrical properties depending on relative molar ratios of the phases. Results were discussed in the sense of possible reduction of the content of minor phases in ZnO varistors.

  19. Effect of elastic and plastic tensile mechanical loading on the magnetic properties of NGO electrical steel

    Science.gov (United States)

    Leuning, N.; Steentjes, S.; Schulte, M.; Bleck, W.; Hameyer, K.

    2016-11-01

    The magnetic properties of non-grain-oriented (NGO) electrical steels are highly susceptible to mechanical stresses, i.e., residual, external or thermal ones. For rotating electrical machines, mechanical stresses are inevitable and originate from different sources, e.g., material processing, machine manufacturing and operating conditions. The efficiency and specific losses are largely altered by different mechanical stress states. In this paper the effect of tensile stresses and plastic deformations on the magnetic properties of a 2.9 wt% Si electrical steel are studied. Particular attention is paid to the effect of magnetic anisotropy, i.e., the influence of the direction of applied mechanical stress with respect to the rolling direction. Due to mechanical stress, the induced anisotropy has to be evaluated as it is related to the stress-dependent magnetostriction constant and the grain alignment.

  20. Crystal structure and electrical transport properties of single layered perovskite LaSrCoO4

    Science.gov (United States)

    Ahad, Abdul; Shukla, D. K.; Rahman, F.; Majid, S.; Tarachand; Okram, G. S.; Phase, D. M.

    2016-10-01

    We present here investigations on the influence of structure on electrical transport properties of polycrystalline LaSrCoO4 that is single layered perovskite with K2NiF4 type structure synthesized using solid state reaction route. Using Reitveld refinement of X-ray diffraction (XRD) data, it is found that the sample is in single phase with tetragonal structure (space group I4/mmm). Electrical resistivity performed in the temperature range 140-300K shows semiconducting character of the sample. Considerable contrasts in the Co-O bond length is associated with the intermediate spin (IS) state of Co ion that correlates the structural and transport properties. Detailed analysis indicates that the temperature dependent electrical resistivity follows the three-dimensional variable range hopping (VRH) model in low temperature region below 225K. The high temperature (225-300K) resistivity data has been found to follow the thermally activated behaviour.

  1. IONIC CONDUCTIVITY AND ELECTRICAL PROPERTIES OF CARBOXYMETHYL CELLULOSE - NH4Cl SOLID POLYMER ELECTROLYTES

    Directory of Open Access Journals (Sweden)

    N. H. AHMAD

    2016-06-01

    Full Text Available In this present work, carboxymethyl cellulose (CMC – ammonium chloride (NH4Cl solid polymer electrolyte (SPE films were prepared by solution casting method. The ionic conductivity and electrical properties of SPE films were investigated using Electrical Impedance Spectroscopy. SPE film containing 16 wt. % NH4Cl exhibited the highest ionic conductivity of 1.43 x 10-3 S/cm at ambient temperature, 303K. The temperature dependence SPE films showed an Arrhenius-type relation where the regression values obtained from the log conductivity versus reciprocal temperature is close to unity (R2≈1. The electrical properties have been measured as a function of frequency of Ԑr,Ԑi, Mr, Mi shown a non-Debye type behavior

  2. The influence of metal nanoparticles on electrical properties of carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Janas, Dawid, E-mail: dawid.janas@gmail.com; Koziol, Krzysztof K.K., E-mail: kk292@cam.ac.uk

    2016-07-15

    Highlights: • Metal nanoparticles were deposited onto carbon nanotube films. • Metal-CNT nanocomposites showed very interesting electrical, thermal and surface properties. • Tailoring of the size of metal nanoclusters shows big potential for catalysis. - Abstract: First, sputtering deposition of Au, Ag, Pt and Pd resulted in changes to the electrical resistance of carbon nanotube (CNT) films due to electron localization followed by creation of percolation pathways. Metal-CNT composites created this way showed different reaction of electrical resistance to temperature as well as thermal stability. Furthermore, their surface properties show much higher affinity towards aqueous media than as-made CNT films. Finally, we have developed an easy way of tailoring the size of metal clusters on the surface of CNT films depending on the employed deposition and heating conditions. Electrothermal sintering yielded metal clusters of controlled size that showed big potential for the application in catalyst-assisted chemical transformations.

  3. Spatial and temporal dependence of the convective electric field in Saturn’s inner magnetosphere

    Science.gov (United States)

    Andriopoulou, M.; Roussos, E.; Krupp, N.; Paranicas, C.; Thomsen, M.; Krimigis, S.; Dougherty, M. K.; Glassmeier, K.-H.

    2014-02-01

    The recently established presence of a convective electric field in Saturn’s inner and middle magnetosphere, with an average pointing approximately towards midnight and an intensity less than 1 mV/m, is one of the most puzzling findings by the Cassini spacecraft. In order to better characterize the properties of this electric field, we augmented the original analysis method used to identify it (Andriopoulou et al., 2012) and applied it to an extended energetic electron microsignature dataset, constructed from observations at the vicinity of four saturnian moons. We study the average characteristics of the convective pattern and additionally its temporal and spatial variations. In our updated dataset we include data from the recent Cassini orbits and also microsignatures from the two moons, Rhea and Enceladus, allowing us to further extend this analysis to cover a greater time period as well as larger radial distances within the saturnian magnetosphere. When data from the larger radial range and more recent orbits are included, we find that the originally inferred electric field pattern persists, and in fact penetrates at least as far in as the orbit of Enceladus, a region of particular interest due to the plasma loading that takes place there. We perform our electric field calculations by setting the orientation of the electric field as a free, time-dependent parameter, removing the pointing constraints from previous works. Analytical but also numerical techniques have been employed, that help us overcome possible errors that could have been introduced from simplified assumptions used previously. We find that the average electric field pointing is not directed exactly at midnight, as we initially assumed, but is found to be stably displaced by approximately 12-32° from midnight, towards dawn. The fact, however, that the field’s pointing is much more variable in short time scales, in addition to our observations that it penetrates inside the orbit of Enceladus

  4. Electrical and optical properties of gadolinium doped bismuth ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, A., E-mail: soumen.basu@phy.nitdgp.ac.in; Banerjee, M., E-mail: soumen.basu@phy.nitdgp.ac.in; Basu, S., E-mail: soumen.basu@phy.nitdgp.ac.in [Department of Physics, National Institute of Technology, Durgapur-713209 (India); Pal, M. [CSIR-Central Mechanical Engineering Research Institute, Durgapur-713209 (India)

    2014-04-24

    Multiferroic bismuth ferrite (BFO) and gadolinium (Gd) doped bismuth ferrite had been synthesized by a sol-gel method. Particle size had been estimated by Transmission electron microscopy (TEM) and found to decrease with Gd doping. We studied the temperature and frequency dependence of impedance and electric modulus and calculated the grain and grain boundary resistance and capacitance of the investigated samples. We observed that electrical activation energy increases for all the doped samples. Optical band gap also increases for the doped samples which can be used in photocatalytic application of BFO.

  5. Electrical Resistivity and Thermodynamic Properties of Iron Under High Pressure

    Science.gov (United States)

    Hieu, Ho Khac; Hai, Tran Thi; Hong, Nguyen Thi; Sang, Ngo Dinh; Tuyen, Nguyen Viet

    2017-03-01

    In this work, the electrical resistivity and thermodynamic properties of iron under high pressure have been investigated by using the semi-empirical approach. The recently well-established Grüneisen parameter expressions have been applied to derive the Debye frequency and temperature under compression. Using these results combined with the Bloch-Grüneisen law, the resistivity of iron has also been determined up to Earth's core pressures. We show that the electrical resistivity diminished gradually with pressure and saturates at high pressure. Our model gives low electrical resistivity values which are in agreement with the recent experimental measurements. The low resistivity may be attributed to the well-known resistivity saturation effect at high temperature, which was not considered in earlier models of core conductivity.

  6. Mechanical and Electrical Properties of Organogels with Multiwall Carbon Nanotubes

    Science.gov (United States)

    Moniruzzaman, Mohammad; Winey, Karen

    2008-03-01

    Organogels are fascinating thermally reversible viscoelastic materials that are comprised of an organic liquid and low concentrations (typically organogel/carbon nanotube composites using 12-hydroxystearic acid (HSA) as the gelator molecule and pristine and carboxylated multi-wall carbon nanotubes as the nanofillers and 1,2-dichlorobenzene as the organic solvent. We have achieved significant improvements in the mechanical and electrical properties of organogels by incorporating these carbon nanotubes. For example, the linear viscoelastic regime of the HSA organogel, an indicator of the strength of the gel, extends by a factor of 4 with the incorporation of 0.2 wt% of the carboxylated nanotubes. Also, the carbon nanotubes (specially the pristine tubes) improve the electrical conductivity of the organogels, e.g. six orders of magnitude enhancement in electrical conductivity with 0.2 wt% of pristine tubes. Differential scanning calorimetry experiments indicate that the nanotubes do not affect the thermoreversibility of the organogels.

  7. Electrical transport and thermoelectric properties of boron carbide nanowires

    Science.gov (United States)

    Kirihara, Kazuhiro; Mukaida, Masakazu; Shimizu, Yoshiki

    2017-04-01

    The electrical transport and thermoelectric property of boron carbide nanowires synthesized by a carbothermal method are reported. It is demonstrated that the nanowires achieve a higher Seebeck coefficient and power factor than those of the bulk samples. The conduction mechanism of the nanowires at low temperatures below 300 K is different from that of the sintered-polycrystalline and single-crystal bulk samples. In a temperature range of 200–450 K, there is a crossover between electrical conduction by variable-range hopping and phonon-assisted hopping. The inhomogeneous carbon concentration and planar defects, such as twins and stacking faults, in the nanowires are thought to modify the bonding nature and electronic structure of the boron carbide crystal substantially, causing differences in the electrical conductivity and Seebeck coefficient. The effect of boundary scattering of phonon at nanostructured surface on the thermal conductivity reduction is discussed.

  8. Controlling thermal and electrical properties of graphene by strain-engineering its flexural phonons

    Science.gov (United States)

    Conley, Hiram; Nicholl, Ryan; Bolotin, Kirill

    2014-03-01

    We explore the effects of flexural phonons on the thermal and electrical properties of graphene. To control the amplitude of flexural phonons, we developed a technique to engineer uniform mechanical strain between 0 and 1% in suspended graphene. We determine the level of strain, thermal conductivity and carrier mobility of graphene through a combination of mechanical resonance and electrical transport measurements. Depending on strain, we find significant changes in the thermal expansion coefficient, thermal conductivity, and carrier mobility of suspended graphene. These changes are consistent with the expected contribution of flexural phonons.

  9. Electronic properties of pentaorgano[60]fullerenes under an external electric field

    Science.gov (United States)

    Furutani, Sho; Okada, Susumu

    2016-11-01

    The electronic properties of pentaorgano[60]fullerene under an external electric field were studied by combining the density functional theory with the effective screening medium method. Pentaorgano[60]fullerene possess a dipole moment because of their asymmetric molecular form owing to their five functionalized groups. When electrons and holes are injected into the molecule, the magnetic states of the molecule change from S = 1/2 to nonmagnetic and S = 1 triplet states for electron and hole doping, respectively. The asymmetric molecular shape causes the unusual distribution of the accumulated carriers depending on their mutual molecular arrangement in the electric field.

  10. Characterization of the charge transport and electrical properties in solution-processed semiconducting polymers

    Institute of Scientific and Technical Information of China (English)

    WANG LiGuo; ZHANG HuaiWu; TANG XiaoLi; LI YuanXun; ZHONG ZhiYong

    2012-01-01

    The conventional charge transport models based on density- and field-dependent mobility,only having a non-Arrhenius temperature dependence,cannot give good current-voltage characteristics of poly (2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) hole-only devices.In this paper,we demonstrate that the current-voltage characteristics can give a good unified description of the temperature,carrier density and electric field dependence of mobility based on both the Arrhenius temperature dependence and the non-Arrhenius temperature dependence.Furthermore,we perform a systematic study of charge transport and electrical properties for MEH-PPV.It is shown that the boundary carrier density has an important effect on the current-voltage characteristics.Too large or too small values of boundary carder density will lead to incorrect current-voltage characteristics.The numerically calculated carrier density is a decreasing function of the distance to the interface,and the numerically calculated electric field is an increasing function of the distance.Both the maximum of carrier density and the minimum of electric field appear near the interface.

  11. Characterization of the Hole Transport and Electrical Properties in the Small-Molecule Organic Semiconductors

    Science.gov (United States)

    Wang, L. G.; Zhu, J. J.; Liu, X. L.; Cheng, L. F.

    2017-10-01

    In this paper, we investigate the hole transport and electrical properties in a small-molecule organic material N, N'-bis(1-naphthyl)- N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB), which is frequently used in organic light-emitting diodes. It is shown that the thickness-dependent current density versus voltage ( J- V) characteristics of sandwich-type NPB-based hole-only devices cannot be described well using the conventional mobility model without carrier density or electric field dependence. However, a consistent and excellent description of the thickness-dependent and temperature-dependent J- V characteristics of NPB hole-only devices can be obtained with a single set of parameters by using our recently introduced improved model that take into account the temperature, carrier density, and electric field dependence of the mobility. For the small-molecule organic semiconductor studied, we find that the width of the Gaussian distribution of density of states σ and the lattice constant a are similar to the values reported for conjugated polymers. Furthermore, we show that the boundary carrier density has an important effect on the J- V characteristics. Both the maximum of carrier density and the minimum of electric field appear near the interface of NPB hole-only devices.

  12. Frequency-Dependent Properties of Magnetic Nanoparticle Crystals

    Energy Technology Data Exchange (ETDEWEB)

    Majetich, Sara [Carnegie Mellon Univ., Pittsburgh, PA (United States)

    2016-05-17

    In the proposed research program we will investigate the time- and frequency-dependent behavior of ordered nanoparticle assemblies, or nanoparticle crystals. Magnetostatic interactions are long-range and anisotropic, and this leads to complex behavior in nanoparticle assemblies, particularly in the time- and frequency-dependent properties. We hypothesize that the high frequency performance of composite materials has been limited because of the range of relaxation times; if a composite is a dipolar ferromagnet at a particular frequency, it should have the advantages of a single phase material, but without significant eddy current power losses. Arrays of surfactant-coated monodomain magnetic nanoparticles can exhibit long-range magnetic order that is stable over time. The magnetic domain size and location of domain walls is governed not by structural grain boundaries but by the shape of the array, due to the local interaction field. Pores or gaps within an assembly pin domain walls and limit the domain size. Measurements of the magnetic order parameter as a function of temperature showed that domains can exist at high temoerature, and that there is a collective phase transition, just as in an exchange-coupled ferromagnet. Dipolar ferromagnets are not merely of fundamental interest; they provide an interesting alternative to exchange-based ferromagnets. Dipolar ferromagnets made with high moment metallic particles in an insulating matrix could have high permeability without large eddy current losses. Such nanocomposites could someday replace the ferrites now used in phase shifters, isolators, circulators, and filters in microwave communications and radar applications. We will investigate the time- and frequency-dependent behavior of nanoparticle crystals with different magnetic core sizes and different interparticle barrier resistances, and will measure the magnetic and electrical properties in the DC, low frequency (0.1 Hz - 1 kHz), moderate frequency (10 Hz - 500

  13. Lithium and electrical properties of ZnO

    Science.gov (United States)

    Vines, L.; Monakhov, E. V.; Schifano, R.; Mtangi, W.; Auret, F. D.; Svensson, B. G.

    2010-05-01

    Hydrothermal grown n-type ZnO samples have been investigated by deep level transient spectroscopy (DLTS), thermal admittance spectroscopy (TAS), temperature dependent Hall effect (TDH) measurements, and secondary ion mass spectrometry (SIMS) after thermal treatments up to 1500 °C, in order to study the electrical properties of samples with different lithium content. The SIMS results showed that the most pronounced impurities were Li, Al, Si, Mg, Ni, and Fe with concentrations up to ˜5×1017 cm-3. The Li concentration was reduced from ˜1017 cm-3 in as-grown samples to ˜1015 cm-3 for samples treated at 1500 °C, while the concentration of all the other major impurities appeared stable. The results from DLTS and TAS displayed at least five different levels having energy positions of Ec-20 meV, Ec-55 meV, Ec-0.22 eV, Ec-0.30 eV, and Ec-0.57 eV (Ec denotes the conduction band edge), where the Ec-55 meV level is the dominant freeze out level for conduction electrons in samples treated at temperatures TDH measurements showed a pronounced increase in the electron mobility for the heat treated samples, where a peak mobility of 1180 cm2/V s was reached for a sample treated at 1300 °C. The results provide strong evidence that Li in hydrothermal ZnO is almost exclusively in the substitutional configuration (LiZn), supporting theoretical predictions that the formation of LiZn prevails over Li on the interstitial site for Fermi level positions at and above the middle of the band gap.

  14. Electric field dependence of crystallinity in poly(vinylidene fluoride)

    Energy Technology Data Exchange (ETDEWEB)

    Kepler, R.G.; Anderson, R.A.; Lagasse, R.R.

    1982-05-03

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

  15. Electric Field Dependence of Crystallinity in Poly(Vinylidene Fluoride)

    Science.gov (United States)

    Kepler, R. G.; Anderson, R. A.; Lagasse, R. R.

    1982-05-01

    It is shown that the crystallinity of poled films of poly(vinylidene fluoride) can be changed by the application of an electric field. This is the first time that electric-field-induced changes of crystallinity in a polymer have been reported, and this observation confirms the hypothesis that reversible changes in crystallinity with temperature contribute significantly to the pyroelectric effect in poly(vinylidene fluoride).

  16. Data on electrical properties of nickel modified potassium polytitanates compacted powders.

    Science.gov (United States)

    Goffman, V G; Gorokhovsky, A V; Gorshkov, N V; Fedorov, F S; Tretychenko, E V; Sevrugin, A V

    2015-09-01

    Potassium polytitanates are new promising type of ferroelectric ceramic materials with high ionic conductivity, highly polarizable structure and extremely high permittivity. Its structure is formed by [TiO6] octahedral units to layers with mobile potassium and hydroxonium ions in-between. The treatment in solutions containing nickel ions allows forming heterostructured materials which consist of potassium polytitanate particles intercalated by Ni(2+) ions and/or decorated by nickel oxides NiO x . This modification route is fully dependant on solution pH, i.e. in acidic solutions the intercalation process prevails, in alkaline solutions potassium polytitanate is mostly decorated by the oxides. Therefore, electronic structure and electrical properties can be regulated depending on modification conditions, pH and ions concentration. Here we report the data on electric properties of potassium titanate modified in nickel sulfate solutions at different pH.

  17. Data on electrical properties of nickel modified potassium polytitanates compacted powders

    Directory of Open Access Journals (Sweden)

    V.G. Goffman

    2015-09-01

    Full Text Available Potassium polytitanates are new promising type of ferroelectric ceramic materials with high ionic conductivity, highly polarizable structure and extremely high permittivity. Its structure is formed by [TiO6] octahedral units to layers with mobile potassium and hydroxonium ions in-between. The treatment in solutions containing nickel ions allows forming heterostructured materials which consist of potassium polytitanate particles intercalated by Ni2+ ions and/or decorated by nickel oxides NiOx. This modification route is fully dependant on solution pH, i.e. in acidic solutions the intercalation process prevails, in alkaline solutions potassium polytitanate is mostly decorated by the oxides. Therefore, electronic structure and electrical properties can be regulated depending on modification conditions, pH and ions concentration. Here we report the data on electric properties of potassium titanate modified in nickel sulfate solutions at different pH.

  18. Influence of the mechanical fatigue progress on the magnetic properties of electrical steel sheets

    Directory of Open Access Journals (Sweden)

    Karthaus Jan

    2017-06-01

    Full Text Available The purpose of this paper is to study the variation of the magnetic properties of non-oriented electrical steel sheets with the fatigue state during cyclic mechanical loading. The obtained results are central to the design of variable drives such as traction drives in electric vehicles in which varying mechanical loads, e.g. in the rotor core (centrifugal forces, alter the magnetic properties. Specimens of non-oriented electrical steel are subject to a cyclically varying mechanical tensile stress with different stress amplitudes and number of cycles. The specimens are characterised magnetically at different fatigue states for different magnetic flux densities and magnetising frequencies. The measurements show a variation in magnetic properties depending on the number of cycles and stress magnitude which can be explained by changes in the material structure due to a beginning mechanical fatigue process. The studied effect is critical for the estimation of the impact of mechanical material fatigue on the operational behaviour of electrical machines. Particularly in electrical machines with a higher speed where the rotor is stressed by high centrifugal forces, material fatigue occurs and can lead to deterioration of the rotor’s stack lamination.

  19. Electrical Properties of Polymer/Carbon Nanotube Blends

    Science.gov (United States)

    Salgado-Delgado, R.; Olarte-Paredes, A.; Vargas-Galarza, Z.; García-Hernández, E.; Salgado-Delgado, A. M.; Rubio-Rosas, E.; Campos-Álvarez, J.; Castaño, V. M.

    2016-10-01

    Electrical and morphological properties of a novel composite, consisting of polypyrrole (PPy)/carbon black (CB)/carbon nanotubes (CNT), within a polyethylene (PE) matrix, are reported. The electrical properties were studied according to the type of filler (i.e. PPy, CB or CNT). The resistivity, analyzed by the Van der Pauw method, shows values in the range of (1E+15 for PE to 1.07E-01 for M15) Ω cm. The filler is distributed as one phase within the blended matrix and/or at the interface between the polymers, thus producing a highly homogeneous material. The morphology and degree of dispersion of the PPy/CB/CNTs in the PE matrix at different concentrations were investigated by scanning electron microscopy.

  20. Electrical Properties of n-Butyl Acrylate-Grafted Polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.R.; Oh, W.J.; Suh, K.S. [Korea University (Korea, Republic of)

    1997-04-01

    The electrical properties of n-butyl acrylate-grafted polyethylene (PE-g-nBA) were investigated. In PE-g-nBA, hetero charge founded in LDPE slightly increased due to the nBA grafting. Conduction currents decreased with the increase of nBA graft ratio. AC breakdown strength increased and water treeing length decreased with the increase of graft ratio in PE-g-nBA. (author). 4 refs., 6 figs.

  1. Measurement of electric properties of the single supersaturated aerosol droplet

    Institute of Scientific and Technical Information of China (English)

    HE KeJuan; CHENG Hua; ZHU YanYing; WANG LiangYu; ZHANG YunHong

    2008-01-01

    A system for measuring the electric properties of single aerosol droplet is designed and applied to the NaCIO4 aerosol droplet in different relative humidity (RH). The conductance and capacitance are obtained within the whole RH range, especially in the supersaturated state which cannot be acquired from the bulk solution. These results reflect the situation of ions in the droplet macroscopically and supply useful information for other relative study fields, such as crystallogeny and aerography.

  2. Electric properties of La0.8Sr0.2CoO3 nanoceramics

    Institute of Scientific and Technical Information of China (English)

    A.Chuchma(l)a; R.J.Wiglusz; B.Macalik; P.G(l)uchowski; B.Mazurek; W.Str(e)k

    2009-01-01

    The electric measurements were carried out for La0.8Sr0.2CoO3 nanoceramics by using impedance spectroscopy methods.The resistance of sample was practically independent of frequency in measurement range.Its dependence on reciprocal temperature showed quite complicated mechanism of conduction.The most striking property of investigated sample was its resistance decreasing with increasing applied polarization.

  3. Thickness dependence of structural, electrical and optical behaviour of undoped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bouderbala, M.; Hamzaoui, S. [Laboratoire de Microscopie Electronique et des Sciences des Materiaux, Departement de Physique, USTO, B.P. 1505, El-Mnaouer, 31000 Oran (Algeria); Amrani, B. [Department of Physics, Centre Universitaire de Mascara, Mascara 29000 (Algeria)], E-mail: abouhalouane@yahoo.fr; Reshak, Ali H. [Institute of Physical Biology-South Bohemia University, Institute of System Biology and Ecology-Academy of Sciences, Nove Hrady 37333 (Czech Republic); Adnane, M.; Sahraoui, T.; Zerdali, M. [Laboratoire de Microscopie Electronique et des Sciences des Materiaux, Departement de Physique, USTO, B.P. 1505, El-Mnaouer, 31000 Oran (Algeria)

    2008-09-01

    Undoped ZnO thin films of different thicknesses were prepared by r.f. sputtering in order to study the thickness effect upon their structural, morphological, electrical and optical properties. The results suggest that the film thickness seems to have no clear effect upon the orientation of the grains growth. Indeed, the analysis with X-ray diffraction show that the grains were always oriented according to the c(0 0 2)-axis perpendicular to substrate surface whatever the thickness is. However, the grain size was influenced enough by this parameter. An increase in the grain size versus the thickness was noted. For the electrical properties, measurements revealed behaviour very dependent upon thickness. The resistivity decreased from 25 to 1.5x10{sup -3} {omega} cm and the mobility increased from 2 to 37 cm{sup 2} V{sup -1} s{sup -1} when the thickness increased from 70 to 1800 nm while the carrier concentration seems to be less affected by the film thickness and varied slightly remaining around 10{sup 20} cm{sup -3}. Nevertheless, a tendency to a decrease was noticed. This behaviour in electrical properties was explained by the crystallinity and the grain size evolution. The optical measurements showed that all the samples have a strong transmission higher than 80% in the visible range. A slight shift of the absorption edge towards the large wavelengths was observed as the thickness increased. This result shows that the band gap is slightly decreases from 3.37 to 3.32 eV with the film thickness vary from 0.32 to 0.88 {mu}m.

  4. The elusive memristor: properties of basic electrical circuits

    Energy Technology Data Exchange (ETDEWEB)

    Joglekar, Yogesh N; Wolf, Stephen J [Department of Physics, Indiana University Purdue University Indianapolis, Indianapolis, IN 46202 (United States)], E-mail: yojoglek@iupui.edu

    2009-07-15

    We present an introduction to and a tutorial on the properties of the recently discovered ideal circuit element, a memristor. By definition, a memristor M relates the charge q and the magnetic flux {phi} in a circuit and complements a resistor R, a capacitor C and an inductor L as an ingredient of ideal electrical circuits. The properties of these three elements and their circuits are a part of the standard curricula. The existence of the memristor as the fourth ideal circuit element was predicted in 1971 based on symmetry arguments, but was clearly experimentally demonstrated just last year. We present the properties of a single memristor, memristors in series and parallel, as well as ideal memristor-capacitor (MC), memristor-inductor (ML) and memristor-capacitor-inductor (MCL) circuits. We find that the memristor has hysteretic current-voltage characteristics. We show that the ideal MC (ML) circuit undergoes non-exponential charge (current) decay with two time scales and that by switching the polarity of the capacitor, an ideal MCL circuit can be tuned from overdamped to underdamped. We present simple models which show that these unusual properties are closely related to the memristor's internal dynamics. This tutorial complements the pedagogy of ideal circuit elements (R, C and L) and the properties of their circuits, and is aimed at undergraduate physics and electrical engineering students.

  5. Measuring of Electrical Properties of MWNT-Reinforced PAN Nanocomposites

    Directory of Open Access Journals (Sweden)

    Sliman Almuhamed

    2012-01-01

    Full Text Available Nano-web sheets of polyacrylonitrile (PAN reinforced by carbon nanotubes (CNT were prepared by electrospinning process. Multi wall nanotubes (MWNT were dispersed mechanically by high shear mixing using a homogenizer device. It has been found that the spinning solution presented an electrical percolation threshold less than 0.5 wt.% of MWNT. Electrical volume and surface conductivity of the obtained nano-webs was studied by measuring the electrical volume resistance and surface resistance thanks to home-made plate electrodes. Scanning electron microscope (SEM has been used to characterize the nano-web sheets produced. The average filament diameters range from 320 to 750 nm depending on the concentration of CNT and of PAN. From an electrical point of view, it has been observed that the electrical volume conductivity increases by about six orders of magnitude from 2×10−12 S/m for pristine PAN to 4×10−6 S/m for PAN charged by MWNT. Increasing the pressure on the specimen induces an exponential decrease of the volume resistivity while surface resistivity shows no significant changes, neither between pristine PAN and reinforced nano-webs, nor among reinforced nano-web in relation to MWNT concentration (in the limit of the study. This observed behavior is very interesting in the context of sensor developments.

  6. Transport Properties of Two-Dimensional Electron Gases in Antiparallel Magnetic-Electric Barrier Structures

    Institute of Scientific and Technical Information of China (English)

    PING Yun-Xia; CHENG Ze

    2006-01-01

    We study theoretically transport properties of two-dimensional electron gases through antiparallel magnetic electric barrier structures. Two kinds of magnetic barrier configurations are employed: one is that the strength of the double δ-function in opposite directions is equal and the other is that the strength is unequal. Similarities and differences of electronic transports are presented. It is found that the transmission and the conductance depend strongly on the shape of the magnetic barrier and the height of the electric barrier. The results indicate that this system does not possess any spin filtering and spin polarization and electron gases can realize perfect resonant tunneling and wave-vector filtering properties. Moreover, the strength of the effect of the inhomogeneous magnetic field on the transport properties is discussed.

  7. Studying Some of Electrical and Mechanical Properties for Kevlar Fiber Reinforced Epoxy

    Science.gov (United States)

    Rafeeq, Sewench N.; Hussein, Samah M.

    2011-12-01

    As ordinary known the ability of synthesizing electrical conducting polymer composites is possible but with poor mechanical properties, for the solution of this problem, we carried out this study in order to obtain that both properties. Three methods were applied for preparing the conductive polyaniline (PANI) composites using Kevlar fiber fabric as substrate for the deposition of the PANI at one time and the prepared composite (EP/Kevlar fiber) at others. The chemical oxidative method was adopted for polymerization of the aniline and simultaneously protonated of PANI with a hydrochloric acid at concentration (1M). Two kinds of oxidation agents (FeCl3.6H2O) and ((NH4)2S2O8) were used. The electrical measurements indicate the effect of each preparation method, kind of oxidant agent and the kind of mat erial which PANI deposited on the electrical results. The conductivity results showed that the prepared composites lie within semiconductors region. Temperature—dependence of electric conductivity results showed semiconductors and conductors behavior of this material within the applied temperature ranges. The mechan ical property (tensile strength) was studied. X-ray diffraction study showed the crystalline structure for EP/Kevlar fiber/PANI composites prepared by the three methods. These results gave optimism to the synthesis of conductive polymer composites with excellent mechanical properties..

  8. Processing dependent properties of silica xerogels for interlayer dielectric applications

    Science.gov (United States)

    Jain, Anurag

    One of the current and near future research focus in microelectronics is to integrate copper with a new low dielectric constant (K) material. The traditional low K is dense SiO2 (K = 4). Introducing porosity in materials with silica backbone is promising as processing and integration methods are well known. This thesis focuses on studying silica xerogel, also known as nanoporous silica. A new low-K material has to be tested for an array of electrical, mechanical, thermal, and chemical properties before it is deemed successful to replace dense SiO2. These properties of silica xerogels are characterized using various analytical techniques and the effect of processing conditions is studied. The property data is explained by the models and mechanisms relating processing-structure-property behavior. The processing effects on thermal and mechanical properties are studied in great detail and the theories for generic porous low-K materials are developed. The xerogel films are processed at ambient conditions and crack free, thick (0.5--4 mum), highly porous (˜25--90%) films are obtained. Two methods of porosity control were used. One is the traditional single solvent (ethanol) method and another is a binary solvent (mixture of ethanol and ethylene glycol) method. The films underwent aging and silylation procedures to make the backbone stiff and hydrophobic. Sintering of xerogel films eliminates defects and organics and additional condensation reactions make matrix more connected, dense and ordered. Films were characterized for their refractive index, thickness, porosity, pore size and surface roughness. Dielectric constant measurements at 1 MHz show that K varies linearly with porosity. Dielectric loss tangents are low and breakdown strength meets the standards. FTIR and XPS analysis show that films are stable chemically and remain hydrophobic even after boiling in water. Mechanical and thermal properties of porous materials are dependent on the microstructure and various

  9. Effects of the electric field on the properties of ZnO-graphene composites: a density functional theory study.

    Science.gov (United States)

    Geng, Wei; Zhao, Xuefei; Zan, Wenyan; Liu, Huanxiang; Yao, Xiaojun

    2014-02-28

    In this work, the effects of the electric field on the properties of ZnO-graphene composites were theoretically studied using density functional theory calculations. Three types of ZnO-graphene composites including composites of pristine graphene, graphene with defects as well as graphene oxide and a ZnO bilayer were studied. We calculated and analyzed the binding energies, charge transfer, band structures and work functions of the above composites under the external electric fields. The DFT calculation results demonstrate that the binding energies are sensitive to the electric field, and increasing the external electric field gives rise to stronger binding energies. The extent of charge transfer is correlated with the magnitude of the external electric field, but the band gaps are hardly affected by the external electric field. The work functions vary depending on the different structures of the composites and surface sides, and they are also tunable by the external electric field.

  10. Effect of multilayer structure, stacking order and external electric field on the electrical properties of few-layer boron-phosphide.

    Science.gov (United States)

    Chen, Xianping; Tan, Chunjian; Yang, Qun; Meng, Ruishen; Liang, Qiuhua; Jiang, Junke; Sun, Xiang; Yang, D Q; Ren, Tianling

    2016-06-28

    Development of nanoelectronics requires two-dimensional (2D) systems with both direct-bandgap and tunable electronic properties as they act in response to the external electric field (E-field). Here, we present a detailed theoretical investigation to predict the effect of atomic structure, stacking order and external electric field on the electrical properties of few-layer boron-phosphide (BP). We demonstrate that the splitting of bands and bandgap of BP depends on the number of layers and the stacking order. The values for the bandgap show a monotonically decreasing relationship with increasing layer number. We also show that AB-stacking BP has a direct-bandgap, while ABA-stacking BP has an indirect-bandgap when the number of layers n > 2. In addition, for a bilayer and a trilayer, the bandgap increases (decreases) as the electric field increases along the positive direction of the external electric field (E-field) (negative direction). In the case of four-layer BP, the bandgap exhibits a nonlinearly decreasing behavior as the increase in the electric field is independent of the electric field direction. The tunable mechanism of the bandgap can be attributed to a giant Stark effect. Interestingly, the investigation also shows that a semiconductor-to-metal transition may occur for the four-layer case or more layers beyond the critical electric field. Our findings may inspire more efforts in fabricating new nanoelectronics devices based on few-layer BP.

  11. The electroresponse properties of alginate films under the electric field

    Energy Technology Data Exchange (ETDEWEB)

    Kim, I.J.; Kang, H.W.; Jeong, C.N. [Sunchon National University, Sunchon (Korea)

    2002-05-01

    Alginate is a natural ionic polymer including numerous anionic groups and can be actuated by the ionic group under the electric field. The crosslinked alginate films were fabricated with CaCl{sub 2}. The thermal, mechanical and electroresponse properties of the films were investigated by thermogravimetric analysis, tensile and bending tests. The initial degradation and tensile strength increased according to the degree of crosslinking. Also, the swelling ratio of the films increased with decreasing degree of crosslinking and increasing pH due to free volume and electrostatic repulsion. The films actuated by an electric stimulus exhibited gentle and flexible action like a pendulum. In the electric field, the electric stimuli such as the applied voltage, ionic strength and kind of electrolyte solution had an effect on the electroresponse of the films. Alginate films with 5 wt% crosslinking agent showed the highest bending angle and reversible bending behavior. When the ionic strength of NaCl and KCI electrolyte solution was 0.1 M, the films showed the highest electroresponse. The bending behavior of the films increased with the applied voltage. (author). 18 refs., 12 figs.

  12. Electrical transport properties of manganite powders under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M.G. [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina); Leyva, A.G. [Gerencia de Investigacion y Aplicaciones, CAC, Comision Nacional de Energia Atomica, Gral Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Acha, C., E-mail: acha@df.uba.ar [Laboratorio de Bajas Temperaturas, Departamento de Fisica, FCEyN, UBA, and IFIBA (CONICET), Ciudad Universitaria, (C1428EHA) Buenos Aires (Argentina)

    2012-08-15

    We have measured the electrical resistance of micrometric to nanometric powders of the La{sub 5/8-y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (LPCMO with y=0.3) manganite for hydrostatic pressures up to 4 kbar. By applying different final thermal treatments to samples synthesized by a microwave assisted denitration process, we obtained two particular grain characteristic dimensions (40 nm and 1000 nm) which allowed us to analyze the grain size sensitivity of the electrical conduction properties of both the metal electrode interface with manganite (Pt/LPCMO) and the intrinsic intergranular interfaces formed by the LPCMO powder, conglomerate under the only effect of external pressure. We also analyzed the effects of pressure on the phase diagram of these powders. Our results indicate that different magnetic phases coexist at low temperatures and that the electrical transport properties are related to the intrinsic interfaces, as we observe evidences of a granular behavior and an electronic transport dominated by the Space Charge limited Current mechanism.

  13. Experimental and theoretical investigation of temperature-dependent electrical fatigue studies on 1-3 type piezocomposites

    Science.gov (United States)

    Mohan, Y.; Arockiarajan, A.

    2016-03-01

    1-3 type piezocomposites are very attractive materials for transducers and biomedical application, due to its high electromechanical coupling effects. Reliability study on 1-3 piezocomposites subjected to cyclic loading condition in transducer application is one of the primary concern. Hence, this study focuses on 1-3 piezocomposites for various PZT5A1 fiber volume fraction subjected to electrical fatigue loading up-to 106 cycles and at various elevated temperature. Initially experiments are performed on 1-3 piezocomposites, in order to understand the degradation phenomena due to various range in amplitude of electric fields (unipolar & bipolar), frequency of applied electric field and for various ambient temperature. Performing experiments for high cycle fatigue and for different fiber volume fraction of PZT5A1 is a time consuming process. Hence, a simplified macroscopic uni-axial model based on physical mechanisms of domain switching and continuum damage mechanics has been developed to predict the non-linear fatigue behaviour of 1-3 piezocomposites for temperature dependent electrical fatigue loading conditions. In this model, damage effects namely domain pinning, frozen domains and micro cracks, are considered as a damage variable (ω). Remnant variables and material properties are considered as a function of internal damage variable and the growth of the damage is derived empirically based on the experimental observation to predict the macroscopic changes in the properties. The measured material properties and dielectric hysteresis (electric displacement vs. electric field) as well as butterfly curves (longitudinal strain vs. electric field) are compared with the simulated results. It is observed that variation in amplitude of bipolar electric field and temperature has a strong influence on the response of 1-3 piezocomposites.

  14. Experimental and theoretical investigation of temperature-dependent electrical fatigue studies on 1-3 type piezocomposites

    Directory of Open Access Journals (Sweden)

    Y. Mohan

    2016-03-01

    Full Text Available 1-3 type piezocomposites are very attractive materials for transducers and biomedical application, due to its high electromechanical coupling effects. Reliability study on 1-3 piezocomposites subjected to cyclic loading condition in transducer application is one of the primary concern. Hence, this study focuses on 1-3 piezocomposites for various PZT5A1 fiber volume fraction subjected to electrical fatigue loading up-to 106 cycles and at various elevated temperature. Initially experiments are performed on 1-3 piezocomposites, in order to understand the degradation phenomena due to various range in amplitude of electric fields (unipolar & bipolar, frequency of applied electric field and for various ambient temperature. Performing experiments for high cycle fatigue and for different fiber volume fraction of PZT5A1 is a time consuming process. Hence, a simplified macroscopic uni-axial model based on physical mechanisms of domain switching and continuum damage mechanics has been developed to predict the non-linear fatigue behaviour of 1-3 piezocomposites for temperature dependent electrical fatigue loading conditions. In this model, damage effects namely domain pinning, frozen domains and micro cracks, are considered as a damage variable (ω. Remnant variables and material properties are considered as a function of internal damage variable and the growth of the damage is derived empirically based on the experimental observation to predict the macroscopic changes in the properties. The measured material properties and dielectric hysteresis (electric displacement vs. electric field as well as butterfly curves (longitudinal strain vs. electric field are compared with the simulated results. It is observed that variation in amplitude of bipolar electric field and temperature has a strong influence on the response of 1-3 piezocomposites.

  15. Electrical properties of transparent conductive ATO coatings obtained by spray pyrolysis

    Science.gov (United States)

    Zinchenko, T. O.; Kondrashin, V. I.; Pecherskaya, E. A.; Kozlyakov, A. S.; Nikolaev, K. O.; Shepeleva, J. V.

    2017-08-01

    Transparent conductive coatings based on thin films of metal oxides have been widely spread in various optoelectronic devices and appliances. It is necessary to determine the influence of preparation conditions on coatings properties for their use in the solution of certain tasks. Thin films of tin dioxide were obtained by the method of spray pyrolysis on glass substrates. Surface resistance and resistivity, concentration and mobility of charge carriers, the conductivity were measured, and the dependences showing the effect of preparation conditions on electrical properties of optically transparent coatings.

  16. Dependence of electric strength on the ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Čaja, Alexander, E-mail: alexander.caja@fstroj.uniza.sk, E-mail: patrik.nemec@fstroj.uniza.sk, E-mail: milan.malcho@fstroj.uniza.sk; Nemec, Patrik, E-mail: alexander.caja@fstroj.uniza.sk, E-mail: patrik.nemec@fstroj.uniza.sk, E-mail: milan.malcho@fstroj.uniza.sk; Malcho, Milan, E-mail: alexander.caja@fstroj.uniza.sk, E-mail: patrik.nemec@fstroj.uniza.sk, E-mail: milan.malcho@fstroj.uniza.sk [University of Žilina, Faculty of Mechanical Engineering, Department of Power Engeneering, Univerzitná 1, 010 26 Žilina (Slovakia)

    2014-08-06

    At present, the volume concentration of electronic components in their miniaturization to different types of microchips and increasing their performance raises the problem of cooling such elements due to the increasing density of heat flow of heat loss. Compliance with safe operating temperature of active semiconductor element is very closely related to the reliability and durability not only components, but also the entire device. Often it is also necessary to electrically isolate the unit from the side of the cooler air. Cooling demand by natural convection is typical for applications with high operating reliability. To the reliability of the system for removing heat loss increased, it is necessary to minimize need to use the mechanically or electrically powered elements, such as circulation pumps or fans. Experience to date with applications of heat pipe in specific systems appears to be the most appropriate method of cooling.

  17. Experimental Study on Electric Properties of Carbon Fiber Reinforced Concrete

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    According to the phenomenon that the physical properties have a great effect on the electric capability of carbon fiber reinforced concrete, the author researched the relationship between DC resistance of carbon fiber reinforced concrete and curing age using the two-probe method. Then the effect of insulative area,location and quantity on DC resistance of carbon fiber reinforced concrete was investigated at different curing age with analysis of hydration. The results suggest that DC resistance increases greatly with its curing age, which illustrates the relationship like Gaussian curve. In every curing ages the electric capability of carbon fiber reinforced concrete weakenes with the increase of insulative area. In same curing ages, section and insulative area, the more the quantity of insulation, the stronger the conductibility. The insulative location in optimal position can only result in optimal conductibility.

  18. Electrical and Mechanical Properties of PMMA/nano-ATO Composites

    Institute of Scientific and Technical Information of China (English)

    Wei Pan; Huiqin Zhang; Yan Chen

    2009-01-01

    Conducting nanocomposites of poly (methyl methacryiate) (PMMA) and antimony doped tin oxide (ATO)were prepared by solution blending. The influences of ATO content on the electrical conductivity, thermal stability, and mechanical properties of the nanocomposites were investigated. A homogeneous dispersion of silane coupling agent modified ATO was achieved in PMMA matrix as evidenced by scanning electron microscopy. The resultant PMMA/silane-ATO nanocomposites were electrically conductive with significant conductivity enhancement at 4 wt pct. It was found that the composition at 4 wt pct ATO gave the higher tensile strength. Furthermore, it gave the largest elongation at break value among all the compositions.Thermal stability of the nanocornposites was remarkably enhanced by the incorporation of silane-ATO.

  19. Preparation and Electrical Property of Polypyrrole-Polyethylene Composite

    Science.gov (United States)

    Yoshino, Katsumi; Yin, Xiao Hong; Morita, Shigenori; Nakanishi, Yutaka; Nakagawa, Shinichi; Yamamoto, Hideo; Watanuki, Toshiro; Isa, Isao

    1993-02-01

    Polypyrrole-polyethylene composites have been prepared by pressing the mixture of polypyrrole coated and non-coated polyethylene spheres. Electrical conductivity is enhanced by more than 16 orders of magnitude and its activation energy decreases remarkably at concentration of polypyrrole coated polyethylene above around 10-20%, which corresponds to effective polypyrrole concentration of 0.1-0.2%. These characteristics can be explained by a percolation model. That is, at this concentration electrodes are bridged by conducting channel of doped polypyrrole. Thermoelectric power increases in proportion to absolute temperature and is independent on concentration of polypyrrole coated polyethylene sphere above 30%, which support the percolation model. The electrical property of this polypyrrole-polyethylene composite is found to be stable up to 160°C. The application of this composite to the semiconducting layer of a cable has been proposed.

  20. Electrical conductivity and dielectric properties of potassium sulfamate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.S.; Iype, L.; Rajesh, R. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam (India); Varughese, G. [Department of Physics, Catholicate College, Pathanamthitta, Kerala (India); Joseph, G. [Department of Physics, Sacred Heart College, Thevera, Cochin, Kerala (India); Louis, G. [Department of Physics, Cochin University of Science and Technology, Cochin (India)

    2011-10-15

    Single crystals of potassium sulfamate are grown by the method of slow evaporation at constant temperature. AC electrical conductivity of potassium sulfamate is measured in the temperature range 300-430 K and in the frequency region between 100 Hz and 3 MHz along the a, b and c-axes. Complex impedance spectroscopy is used to investigate the frequency response of the electrical properties of the potassium sulfamate single crystal. Temperature variation of AC conductivity and dielectric measurements show a slope change around 345 K for both heating and cooling run and this anomaly is attributed as phase transition, which is well supported by the DSC measurements. Value of loss tangent in the temperature region 330-400 K is found to be very low. Activation energies for the conduction process are calculated along the a, b and c-axes. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Effect of an electric field on the properties of BN Möbius stripes

    Energy Technology Data Exchange (ETDEWEB)

    Lemos de Melo, J. [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900 João Pessoa, PB (Brazil); Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900 João Pessoa, PB (Brazil); Kaschny, J.R. [Instituto Federal da Bahia, Campus Vitória da Conquista, Av. Amazonas 3150, 45075-265 Vitória da conquista, BA (Brazil)

    2014-09-15

    In the present work, we present a first-principles study on the effects of an external electric field on the structural stability and electronic properties of boron nitride Möbius stripes with armchair and zigzag chirality. The calculation results indicate that the gap energy can be remarkably reduced by the application of an external field. Such reduction is in principle attributed to the occurrence of Stark effect, which significance depends on the orientation of the applied field relative to the stripe axis. Moreover, the electric field produces significant changes on dipole momentum of the structure and induces a negative shift on the calculated total energy, reducing the obtained formation energy. - Highlights: • The gap energy is remarkably reduced by the application of an external field. • The electric field produces significant changes on dipole momentum. • The field induces a negative shift on the total energy due to Stark effect.

  2. Study of electrical properties of polyvinylpyrrolidone/polyacrylamide blend thin films

    Indian Academy of Sciences (India)

    A Rawat; H K Mahavar; A Tanwar; P J Singh

    2014-04-01

    Electrical properties of polyvinylpyrrolidone, polyacrylamide and their blend thin films have been investigated as a function of temperature and frequency. The films were prepared using solution casting method and the measurements on films were carried out at different temperatures ranging from 305 to 345 K covering a frequency range from 102 to 105 Hz. The conductivity of film samples was found to increase upon increasing the temperature. Lowering of activation energy by increasing the polyvinylpyrrolidone percentage may be due to the predominance of ion conduction mechanism caused by polyvinylpyrrolidone in the blend. The permittivity (r) and dielectric loss (i) were found to decrease upon increasing frequency. Temperature and frequency dependence of impedance, relaxation time and electric modulus of thin film samples have also been studied. From electric modulus formalism, polarization and conduction relaxation behaviour in the film samples have been discussed.

  3. Automated system of measuring the temperature dependence of the electrical conductivity and the thermal emf

    Energy Technology Data Exchange (ETDEWEB)

    Listovnichii, V.E.; Fenyuk, P.F.; Batalin, V.G.; Brodskii, V.P.; Bulanova, M.V.; Dragan, T.E.; Yatsenko, V.A.

    1987-10-01

    The automated measurement system the authors developed for the temperature dependence of the electrical conductivity and the thermal emf - MERA - permits automatic control of the course of the experiment on several specimens simultaneously in one cycle, including the programmed change in specimen temperature, collection, primary and statistical test data processing, and mapping of the information in a given volume on different carriers. The MERA automated system is used to construct composition-properties diagrams and for the physicochemical analysis of transition and rare-earth metal alloys. Its application permits a sharp increase in the volume of test data being processed and a more-than-two-orders increase in the rate of measurement, and their realization in a dynamic mode for satisfactory statistical test-data characteristics.

  4. The biological response of cells to nanosecond pulsed electric fields is dependent on plasma membrane cholesterol.

    Science.gov (United States)

    Cantu, Jody C; Tarango, Melissa; Beier, Hope T; Ibey, Bennett L

    2016-11-01

    Previous work from our laboratory demonstrated nanopore formation in cell membranes following exposure to nanosecond pulsed electric fields (nsPEF). We observed differences in sensitivity to nsPEF in both acute membrane injury and 24h lethality across multiple cells lines. Based on these data, we hypothesize that the biological response of cells to nsPEF is dependent on the physical properties of the plasma membrane (PM), including regional cholesterol content. Results presented in this paper show that depletion of membrane cholesterol disrupts the PM and increases the permeability of cells to small molecules, including propidium iodide and calcium occurring after fewer nsPEF. Additionally, cholesterol depletion concurrently decreases the "dose" of nsPEF required to induce lethality. In summary, the results of the current study suggest that the PM cholesterol composition is an important determinant in the cellular response to nsPEF. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Morphological and electrical properties of zirconium vanadate doped with cesium

    Directory of Open Access Journals (Sweden)

    Marwa F. Elkady

    2014-09-01

    Full Text Available Cesium doped zirconium vanadate ZrV2O7 with different Cs dopant content (Cs/Zr varied from 0 to 0.5 in weight ratio were fabricated by hydrothermal technique at 120 °C for 60 min. The synthesized materials are thermally treated using microwave technique. The structural and morphological properties of the synthesized materials and thermally treated samples were investigated using XRD and SEM respectively. It was evident that all synthesized specimens have cubic phase structural without any extra phase but after heat treatment Orthorhombic phase appear with doped samples. However, the morphological structure of the doped synthesized materials has transferred from nanoparticles into rods aspect with heat treatment for the different dopant ratio. Moreover, the electrical properties of both the synthesized and thermally treated materials are studied by AC impedance measurements. The results indicated that the ionic conductivity of Cs-doped ZrV2O7 materials decreased by increasing the dopant ratio while that thermally treated samples the ionic conductivity increase by increasing the dopant ratio. Finally, the concentration of cesium dopants is found to play crucial role in tuning the morphology and electrical properties of nanostructures.

  6. Electrical Property Characterization of Neural Stem Cells in Differentiation.

    Directory of Open Access Journals (Sweden)

    Yang Zhao

    Full Text Available Electrical property characterization of stem cells could be utilized as a potential label-free biophysical approach to evaluate the differentiation process. However, there has been a lack of technology or tools that can quantify the intrinsic cellular electrical markers (e.g., specific membrane capacitance (Cspecific membrane and cytoplasm conductivity (σcytoplasm for a large amount of stem cells or differentiated cells. In this paper, a microfluidic platform enabling the high-throughput quantification of Cspecific membrane and σcytoplasm from hundreds of single neural stem cells undergoing differentiation was developed to explore the feasibility to characterize the neural stem cell differentiation process without biochemical staining. Experimental quantification using biochemical markers (e.g., Nestin, Tubulin and GFAP of neural stem cells confirmed the initiation of the differentiation process featured with gradual loss in cellular stemness and increased cell markers for neurons and glial cells. The recorded electrical properties of neural stem cells undergoing differentiation showed distinctive and unique patterns: 1 in the suspension culture before inducing differentiation, a large distribution and difference in σcytoplasm among individual neural stem cells was noticed, which indicated heterogeneity that may result from the nature of suspension culture of neurospheres; and 2 during the differentiation in adhering monolayer culture, significant changes and a large difference in Cspecific membrane were located indicating different expressions of membrane proteins during the differentiation process, and a small distribution difference in σcytoplasm was less significant that indicated the relatively consistent properties of cytoplasm during the culture. In summary, significant differences in Cspecific membrane and σcytoplasm were observed during the neural stem cell differentiation process, which may potentially be used as label

  7. Electrical Property Analytical Prediction on Archimedes Chiral Carbon Nanoscrolls

    Science.gov (United States)

    Hassanzadazar, M.; Ahmadi, M. T.; Ismail, Razali; Goudarzi, Hadi

    2016-10-01

    Carbon nanoscrolls (CNS) with flexible exterior areas and interesting electrical and mechanical properties have gained interest in recent years, both experimentally and theoretically. These structures have been employed as ion channels, tunable water channels, molecular sensors, and gene and drug distribution systems. In this study, electrical behaviour of all types of CNS containing armchair, zigzag, and chiral CNSs band structure is investigated. In armchair CNSs, the small band gap among valence and the conduction band as a pseudo-gap are reported, which reveals a semimetallic property for some of these CNSs. This small band gap, as a result of layer interaction, has been confirmed. Also, in many other types of armchair CNSs at the Fermi level, related levels cross each other, illustrating metallic characteristics. On the other hand, our numerical results show small band gaps for zigzag types of CNSs, which means that they are semiconductors. However, it cannot be considered as a general occurrence because only in rare circumstances is a very small band gap observed that gives rise to semimetallic CNSs. In addition, the electrical properties of chiral CNSs are explored. Small band gaps between the associated valence and the conduction band reveals that chiral CNSs mainly exhibit semiconducting behaviour. Finally, all the numerical results are tabulated in the form of a CNS periodic table and a symmetric arrangement with respect to the armchair nanoscrolls and as a table diagonal data for the chiral CNSs is noticed. In addition, this investigation highlights the variations of the energy structure of chiral CNSs with respect to their length. Presented results offer significant potential for chiral CNSs as an alternative to silicon-based sensors in nanotechnology. Therefore, the band gap variations in the presence of attached materials as a sensor platform need to be explored.

  8. Tissue electrical properties monitoring for the prevention of pressure sore.

    Science.gov (United States)

    Ching, Congo Tak-Shing; Chou, Mei-Yun; Jiang, Siou-Jhen; Huang, Su-Hua; Sun, Tai-Ping; Liu, Wei-Hao; Liu, Chia-Ming

    2011-12-01

    Pressure sores are a significant problem in the healthcare sector. Although they may cause considerable morbidity, they are preventable. The objectives of this study are to (1) investigate the electrical properties of a tissue close to and away from the pressure sore site, and (2) establish a new approach for objective, reliable, low-cost and noninvasive screening or detection of pressure sore in its early stage. Randomised controlled trial. Fifteen patients participated in this study. They all had stage I or stage II sacral pressure sores. Tiny surface electrodes in four-electrode configuration were used for all tissue electrical properties measurements recorded over the frequency range of 30-10 MHz. Intraclass correlation coefficient (ICC) showed that all measurements (ICC > 0.90 for all measurements) had good reliability and validity. The real part of impedance (R) and the imaginary part of impedance (X) of a tissue measured close to the pressure sore site was found to be significantly smaller (p pressure sore site at a specific frequency range (R: 30.00-38.55 Hz; X: 43.95-606.40 Hz). It was also found that the extracellular resistance (R(e)) and the ratio of extracellular resistance to intracellular resistance (R(e)/R(i)) of a tissue measured close to the pressure sore site were significantly smaller (p pressure sore site. Since the electrical properties (R, X, R(e), R(e)/R(i) ) of a tissue close to, and away from, the pressure sore site can be significantly distinguished, a potentially promising method for the screening of pressure sores at an early stage has been proposed.

  9. Some Thermal and Electrical Properties of Candelilla Wax

    OpenAIRE

    2002-01-01

    We report the values of some thermal and electrical properties of Candelilla Wax (euphorbia cerifera). The open-cell photoacoustic technique and another photothermic technique - based on the measure of the temperature decay of a heated sample - were employed to obtain the thermal diffusivity ($\\alpha_{s} = 0.026 \\pm 0.00095 {cm}^{2}{/sec}$) as well as the thermal conductivity ($k=2.132 \\pm 0.16 {W/mK}$) of this wax. The Kelvin null method was used to measure the dark decay of the surface pote...

  10. Magnetoactive elastomeric composites: Cure, tensile, electrical and magnetic properties

    Indian Academy of Sciences (India)

    K Sasikumar; G Suresh; K A Thomas; Reji John; V Natarajan; T Mukundan; R M R Vishnubhatla

    2006-11-01

    Magnetically active elastomer materials were prepared by incorporating nickel powder in synthetic elastomeric matrices, polychloroprene and nitrile rubber. Cure characteristics, mechanical, electrical and magnetic properties were experimentally determined for different volume fractions of magnetoactive filler. The cure time decreases sharply for initial filler loading and the decrease is marginal for additional loading of filler. The tensile strength and modulus at 100% strain was found to increase with increase in the volume fraction of nickel due to reinforcement action. The magnetic impedance and a.c. conductivity are found to increase with increase in volume fraction of nickel as well as frequency.

  11. Electrical Properties of n-Butylacrylate Grafted Polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chang R. [CRIEPI Post-Doc. (Japan); Oh, Woo J.; Suh, Kwang S. [Korea University (Korea, Republic of); Kim, Ok [Taekwang Research Center (Korea, Republic of)

    1998-01-01

    Electrical properties such as space charge accumulation, conduction, dielectric breakdown and water treeing of n-butylacrylate-grafted polyethylene ( PE-g-nBA ) were investigated. Heterocharge accumulates in PE-g-nBA and their amount is larger than that in LDPE. Conduction currents and charge mobilities of PE-g-nBAs decreased with the increase of nBA graft ratio, while their conduction mechanisms remain unchanged. Dielectric breakdown strength increased and water treeing length decreased with the increase of graft ratio in PE-g-nBA. (author). 20 refs., 9 figs., 1 tab.

  12. Correlation of Critical Temperatures and Electrical Properties in Titanium Films

    Science.gov (United States)

    Gandini, C.; Lacquaniti, V.; Monticone, E.; Portesi, C.; Rajteri, M.; Rastello, M. L.; Pasca, E.; Ventura, G.

    Recently transition-edge sensors (TES) have obtained an increasing interest as light detectors due to their high energy resolution and broadband response. Titanium (Ti), with transition temperature up to 0.5 K, is among the suitable materials for TES application. In this work we investigate Ti films obtained from two materials of different purity deposited by e-gun on silicon nitride. Films with different thickness and deposition substrate temperature have been measured. Critical temperatures, electrical resistivities and structural properties obtained from x-ray are related to each other.

  13. Radiation Damage Study on the Electrical Properties of Si Diodes

    Science.gov (United States)

    Pascoalino, Kelly C. S.; Gonçalves, Josemary A. C.; Tobias, Carmen C. B.

    2011-08-01

    The aim of this work was to study the radiation damage effects on the electrical properties of Float Zone (FZ) and Magnetic Czochralski (MCz) diodes. The effects were evaluated by measuring the reverse current and capacitance of these devices as a function of the reverse voltage. The irradiation was performed in the Radiation Technology Center (CTR) at IPEN-CNEN/SP using a 60Co irradiator (Gammacell 220-Nordion) with a dose rate of about 2 kGy/h. Samples were irradiated at room temperature in five steps up to an accumulated dose of 603 kGy.

  14. Structural Characterization and Infrared and Electrical Properties of the New Inorganic-Organic Hybrid Compound

    Directory of Open Access Journals (Sweden)

    A. Oueslati

    2013-01-01

    Full Text Available New inorganic-organic hybrid [(C3H74N]2Hg2Cl6 compound was obtained and characterised by single-crystal X-ray diffraction, infrared, and impedance spectroscopy. The latter crystallizes in the monoclinic system (space group C 2/c, with the following unit cell dimensions: (1 Å, (6 Å, (2 Å, and (2. Besides, its structure was solved using 84860 independent reflections leading to . Electrical properties of the material were studied using impedance spectroscopic technique at different temperatures in the frequency range of 209 Hz to 5 MHz. Detailed analysis of the impedance spectrum suggested that the electrical properties of the material are strongly temperature-dependent. The Nyquist plots clearly showed the presence of bulk and grain boundary effect in the compound.

  15. Electrical transport properties of nanocrystalline nonstoichiometric nickel ferrite at and above room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, S. [Department of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India); Sinha, M. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Mandal, M.K. [Department of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India); Pradhan, S.K. [Department of Physics, University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Meikap, A.K., E-mail: meikapnitd@yahoo.com [Department of Physics, National Institute of Technology, Durgapur 713209, West Bengal (India)

    2015-01-15

    The electrical transport properties of chemically prepared nanocrystalline nonstoichiometric nickel ferrite followed by high energy ball milling have been reported. The dc conductivity of the samples shows semiconducting behavior. The adiabatic small polaron model is most suitable for analyzing the dc conductivity at higher temperature, whereas at lower temperature Schnakenberg acoustical one phonon assisted hopping model is suitable. The frequency dependent conductivity has been described by power law σ{sup /}(f)∝f{sup s} and a maximum has been observed in the temperature behavior of ‘s’. The dielectric properties of the samples have been explained in terms of electric modulus vector. Both dc and ac activation energy have been measured for different samples. The metallic electrode and semiconductor junction formed Schottky diode and the diode parameters have been extracted from the capacitance–voltage characteristics.

  16. Spin and valley dependent line-type resonant peaks in electrically and magnetically modulated silicene quantum structures

    Science.gov (United States)

    Zhang, Yuanshan; Guo, Yong

    2017-02-01

    A barrier with a tunable spin-valley dependent energy gap in silicene could be used as a spin and valley filter. Meanwhile, special resonant modes in unique quantum structure can act as energy filters. Hence we investigate valley and spin transport properties in the potential silicene quantum structures, i.e., single ferromagnetic barrier, single electromagnetic barrier and double electric barriers. Our quantum transport calculation indicates that quantum devices of high accuracy and efficiency (100% polarization), based on modulated silicene quantum structures, can be designed for valley, spin and energy filtering. These intriguing features are revealed by the spin, valley dependent line-type resonant peaks. In addition, line-type peaks in different structure depend on spin and valley diversely. The filter we proposed is controllable by electric gating.

  17. Effect of reactive magnetron sputtering parameters on structural and electrical properties of hafnium oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Szymańska, Magdalena, E-mail: magdalena_szymanska@its.waw.pl [Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Motor Transport Institute, Jagiellońska 80, 03-301 Warsaw (Poland); Gierałtowska, Sylwia; Wachnicki, Łukasz [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warsaw (Poland); Grobelny, Marcin; Makowska, Katarzyna [Motor Transport Institute, Jagiellońska 80, 03-301 Warsaw (Poland); Mroczyński, Robert [Warsaw University of Technology, Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland)

    2014-05-01

    Highlights: • Structural and electrical characterization of HfO{sub x} and HfO{sub x}N{sub y} thin films. • Analysis of the influence of deposition process parameters on properties of films. • Investigation of the post-deposition annealing on HfO{sub x} and HfO{sub x}N{sub y} properties. • Experiment has been designed with use of Taguchi's orthogonal arrays. • The most favorable annealing temperature of HfO{sub x} and HfO{sub x}N{sub y} is 300 °C. - Abstract: The purpose of this work was to compare the structural and electrical properties of magnetron sputtered hafnium oxide (HfO{sub x}) and hafnium oxynitride (HfO{sub x}N{sub y}) thin films. A careful analysis of the influence of deposition process parameters, among them: pressure in the reactor chamber, Ar and O{sub 2} flow rate, power applied to the reactor chamber and deposition time, on electro-physical properties of HfO{sub x} and HfO{sub x}N{sub y} layers has been performed. In the course of this work we performed number of experiments by means of Taguchi's orthogonal arrays approach. Such a method allowed for the determination of dielectric layers properties depending on process parameters with relatively low amount of experiments. Moreover, the effects of post-deposition annealing on electrical characteristics of metal–insulator–semiconductor (MIS) structures with HfO{sub x} or HfO{sub x}N{sub y} gate dielectric and its structural properties have also been reported. Investigated hafnia thin films were characterized by means of spectroscopic ellipsometry (SE), electrical characteristics measurements, atomic force microscopy (AFM), X-ray diffraction spectroscopy (XRD) and Rutherford backscattering spectrometry (RBS)

  18. Exploration of electric properties of bone compared to cement: streaming potential and piezoelectirc properties

    Science.gov (United States)

    Dry, Carolyn

    2015-03-01

    Bone is a material after which to model construction materials for many reasons, including its great strength, toughness, and adaptability. This paper focuses on bone's intrinsic ability to adapt to its environment, namely loading conditions. Research on bone's electrical properties reveals that two phenomena occur in bone to allow it to adapt to environmental changes; they are the inherent piezoelectric property of bone and the streaming potential of bone [1]. Together they create charge differences that attract ions to specific regions of the bone, namely those under greatest stress, in order to build up the region to handle the applied load. Research on the utilization of these properties in cement in order to increase adaptability was studied along with 1) the inherent electric properties of the cement itself and 2) considered the introduction of a different polymer or ceramic within the cement to impart piezoelectricity and streaming potential.

  19. Diameter-dependent thermodynamic and elastic properties of metallic nanoparticles

    Science.gov (United States)

    Chandra, Jeewan; Kholiya, Kuldeep

    2015-04-01

    A simple theoretical model has been proposed to study the diameter-dependent properties of metallic nanoparticles, i.e. Ag, Au, Al, Ni, Pb, Cu and Fe. The diameter-dependent thermodynamic properties includes melting temperature, Debye temperature, evaporation temperature, melting enthapy and melting entropy. The model is also extended to study the diameter-dependent elastic properties including bulk modulus, Young's modulus and thermal expansion coefficient. On comparison with available experimental findings and other theoretical approaches, the results obtained with the present formulation depict a close agreement and demonstrate the validity of the method proposed in the present paper.

  20. Dependence of dielectric properties on BT particle size in EP/BT composites

    Institute of Scientific and Technical Information of China (English)

    YANG Xiaojun; YANG Zhimin; MAO Changhui; DU Jun

    2006-01-01

    The polymer-ceramic composites of epoxy resin (EP) and barium titanate (BT) were prepared.BT powders of different BT particle sizes from 100 nm to 1 μm were used in the preparation.The dielectric properties, such as dielectric constant, dielectric loss and electrical breakdown strength, of the EP/BT composites were studied.The morphology of the composites was characterized by the means of scanning electron microscopy (SEM).The results show that the dielectric constant of the composites is much higher than the epoxy matrix at frequency range from 1 kHz to 10 MHz, and it is also obviously dependent on the size of BT particles.The electrical breakdown strength of the composites decreases with the increase of the BT content.The dependence of electrical breakdown strength on BT particle sizes was also discussed.

  1. Dependence of Glass Mechanical Properties on Thermal and Pressure History

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Bauchy, Mathieu

    -equilibrium material, the structure and properties of glass depend not only on its composition, but also on its thermal and pressure histories. Here we review our recent findings regarding the thermal and pressure history dependence of indentation-derived mechanical properties of oxide glasses.......Predicting the properties of new glasses prior to manufacturing is a topic attracting great industrial and scientific interest. Mechanical properties are currently of particular interest given the increasing demand for stronger, thinner, and more flexible glasses in recent years. However, as a non...

  2. Electrical properties of irradiated PVA film by using ion/electron beam

    Science.gov (United States)

    Abdelrahman, M. M.; Osman, M.; Hashhash, A.

    2016-02-01

    Ion/electron beam bombardment has shown great potential for improving the surface properties of polymers. Low-energy charged (ion/electron) beam irradiation of polymers is a good technique to modify properties such as electrical conductivity, structural behavior, and their mechanical properties. This paper reports on the effect of nitrogen and electron beam irradiation on the electrical properties of polyvinyl alcohol (PVA) films. PVA films of 4 mm were exposed to a charged (ion/electron) beam for different treatment times (15, 30, and 60 minutes); the beam was produced from a dual beam source using nitrogen gas with the other ion/electron source parameters optimized. The dielectric loss tangent tan δ , electrical conductivity σ , and dielectric constant ɛ ^' } in the frequency range 100 Hz-100 kHz were measured at room temperature. The variation of dielectric constant and loss tangent as a function of frequency was also studied at room temperature. The dielectric constant was found to be strongly dependent on frequency for both ion and electron beam irradiation doses. The real (ɛ ^' }) and imaginary (ɛ ^' ' }) parts of the dielectric constant decreased with frequency for all irradiated and non-irradiated samples. The AC conductivity showed an increase with frequency for all samples under the influence of both ion and electron irradiation for different times. Photoluminescence (PL) spectral changes were also studied. The formation of clusters and defects (which serve as non-radiative centers on the polymer surface) is confirmed by the decrease in the PL intensity.

  3. Single wall carbon nanotubes and their electrical properties

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Single-wall carbon nanotubes (SWCNTs) were synthesized and purified. A water colloid of SWCNTs was prepared and used to assemble SWCNTs onto a gold film surface. Scanning tunneling microscopy (STM) images showed that short SWCNTs stood on gold film surfaces. Using STM tips made of SWCNTs, a crystal grain image of a gold thin film and an atomic resolution image of highly oriented pyrolytic graphite were successfully obtained. The electrical properties of short SWCNTs, which stood on the surface of gold film, were measured using STM. That SWCNTs stand on gold thin films is a promising technique for studying structures and properties of carbon nanotubes, as well as assembling and fabricating high-intensity coherent electron sources, field emission flat panel display, tips for scanning probe microscopes, new nanoelectronic devices, etc.

  4. Research on lunar materials. [optical, chemical, and electrical properties

    Science.gov (United States)

    Gold, T.

    1978-01-01

    Abstracts of 14 research reports relating to investigations of lunar samples are presented. The principal topics covered include: (1) optical properties of surface and core samples; (2) chemical composition of the surface layers of lunar grains: Auger electron spectroscopy of lunar soil and ground rock samples; (3) high frequency electrical properties of lunar soil and rock samples and their relevance for the interpretation of lunar radar observations; (4) the electrostatic dust transport process; (5) secondary electron emission characteristics of lunar soil samples and their relevance to the dust transportation process; (6) grain size distribution in surface soil and core samples; and (7) the optical and chemical effects of simulated solar wind (2keV proton and a particle radiation) on lunar material.

  5. Electrical and Magnetic Properties of FeSi2 Nanowires

    Institute of Scientific and Technical Information of China (English)

    PENG Zu-Lin; S. Liang

    2008-01-01

    We report the characterization of serf-assembled epitaxially grown FeSi2 nanowires (NWs) in terms of electrical and magnetic properties. NWs grown by reactive deposition epitaxy (RDE) on silicon (110) show dimensions of 1Onm×5nm, and several micrometres in length. By using conductive-AFM (c-AFM), electron transport properties of one single NW is measured, resistivity of a single crystalline FeSi2 NW is estimated to be 225 μΩ·cm.Using superconducting quantum interference device (SQUID), we measure a magnetic moment of 0.3±0.1 Bohr magneton per iron atom for these FeSi2 NWs.

  6. Influence of cooling rate on optical properties and electrical properties of nanorod ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Meizhen, E-mail: gaomz@lzu.edu.c [Key Lab for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou 730000 (China); Liu, Jing; Sun, Huina; Wu, Xiaonan; Xue, Desheng [Key Lab for Magnetism and Magnetic Materials of MOE, Lanzhou University, Lanzhou 730000 (China)

    2010-06-25

    ZnO films are prepared on Ag-coated glass substrates by wet chemical method at low temperature using Zn(NO{sub 3}).6H{sub 2}O and dimethylamine borane complex (DMAB). The structural, electrical and optical properties of ZnO films are investigated by X-ray diffraction, scanning electron microscope, four-point probe method and photoluminescence, respectively. The ZnO film deposited at 90 {sup o}C is the most compact films with a c-axis preferred orientation. The cooling rate affects the optical and electrical properties of ZnO films dramatically. The ZnO films cooled at -15 {sup o}C exhibit the lowest electrical resistivity of 0.525 {Omega} cm and the strongest photoluminescence in visible light. The increase of the conductivity and the enhancement of the photoluminescence are attributed to the increase of oxygen vacancies in the films.

  7. Study of ac electrical properties of aluminium-epoxy composites

    Energy Technology Data Exchange (ETDEWEB)

    Elimat, Z M [Applied Science Department, Ajloun University College, Al-Balqa Applied University, Amman (Jordan); Zihlif, A M [Physics Department, University of Jordan, Amman (Jordan); Ragosta, G [Institute of Chemistry and Polymer Technology (ICTP), CNR-Possouli, Napoli (Italy)], E-mail: adzh@ju.edu.jo

    2008-08-21

    Ac electrical properties of aluminium flakes-epoxy composites were studied as a function of the composition, frequency and temperature. The dielectric constant increased smoothly with an increase in the concentration of aluminium. An increase in the dielectric constant was observed with the temperature as well as with a decrease in the frequency. The observed increase in the values of the dielectric constant with the aluminium concentration was attributed to interfacial polarization. It was found that ac electrical conductivity increases with increasing content of aluminium, temperature and frequency. The observed enhancement in ac conductivity is attributed to the increase in the number of conduction paths created by the aluminium flake contacts in the composite to give a higher electrical conductivity. Also, the activation energy of aluminium flakes-epoxy composites was determined, as well as the values of the dielectric constant. Compared with various theoretical models, Bruggman's formula gives a better fit. The universal power-law model of ac conductivity is observed in epoxy-aluminium composites. The calculated power exponent (about unity) is physically acceptable within this applied model.

  8. Investigation of electrical and optoelectronic properties of zinc oxide nanowires

    Science.gov (United States)

    Zhang, D.; Lee, S. K.; Chava, S.; Berven, C. A.; Katkanant, V.

    2011-10-01

    Zinc oxide (ZnO) nanowires have been synthesized by using tubular furnace chemical vapor deposition technique. The morphology, chemical composition and crystal structure of as-synthesized ZnO nanowires were examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques. Four-terminal current-voltage ( I- V) measurements were employed to study the electrical conductance of ZnO nanowires under various testing gas environments for gas sensing purpose. The I- V curves at temperature ranging from 150 to 300 K were recorded in the testing chamber under vacuum. The Arrhenius plot shows perfect linear relationship between the logarithm of the current I and inverse temperature 1/ T. The donor level of the semiconducting nanowires is about 326 meV. The I- V behaviors were found to be reversible and repeatable with testing gases. The electrical conductivity was enhanced by a factor of four with ambient CO gas compared to that in vacuum and other testing gases. The optoelectronic properties of the ZnO nanowires were obtained by two-terminal I- V measurement method while the nanowires were illuminated by a ruby laser. The electrical conductivity was increased by 60% when the laser was present in comparison to that when the laser was off. Those significant changes suggest that nano-devices constructed by the ZnO nanowires could be used in gas sensing and optical switching applications.

  9. Electrical and Thermal Properties of Mixed Conductors and Superconductors

    Science.gov (United States)

    Thomas, Joyce Albritton

    1995-01-01

    The electrical and thermal properties of three types of electronic materials have been analyzed. Variable -temperature conductivity and thermoelectric power were measured on the following materials: rm V _2O_5 polymer electrolyte nanocomposites, oxygen-deficient rm YBa_2Cu_3O _{x} single crystals, and quaternary chalcogenides, rm K_2Cu_2CeS _4 and rm CsCuCeS_3. Theoretical models were employed to advance the understanding of the conduction mechanisms present in these materials. The sol-gel process has been used to intercalate rm V_2O_5 xerogels with the polymer electrolyte, oxymethylene linked poly(ethylene oxide)-lithium triflate ((a-PEO)_ {n}(LiCF_3SO _3)). The molar ratios of vanadium and lithium to ethylene oxide were varied to examine the effect on the charge transport properties. The V^ {+4} concentration was also increased in an effort to enhance the electrical properties. The conductivity and thermoelectric power data measured parallel to the planes exhibited semiconductor behavior. The thermoelectric power was negative, indicating electrons as the majority charge carriers. Both the conductivity and thermoelectric power data fit a variable-range hopping transport model. Thermoelectric power measurements were performed on various stoichiometries of twinned, rm YBa_2Cu_3O_{x} single crystals. The data were collected along both the ab-plane and c-axis directions to investigate the anisotropic properties of these materials. Several crystals were reoxygenated to either the same x values or different x values. The reoxygenation study was conducted to extend the knowledge of the effect of oxygen content on transport behavior. Theoretical models previously described in the literature were used to examine the conduction mechanisms in the rm YBa_2Cu_3O_{x} single crystals. The quaternary chalcogenides, rm K_2Cu_2CeS_4 and CsCuCeS _3, were also investigated. The amount of Cu present was found to have an effect on the crystal structure of both materials. As a result

  10. Electrical and optoelectronic properties of two-dimensional materials

    Science.gov (United States)

    Wang, Qiaoming

    Electrical and optoelectronic properties of bulk semiconductor materials have been extensively explored in last century. However, when reduced to one-dimensional and two-dimensional, many semiconductors start to show unique electrical and optoelectronic behaviors. In this dissertation, electrical and optoelectronic properties of one-dimensional (nanowires) and two-dimensional semiconductor materials are investigated by various techniques, including scanning photocurrent microscopy, scanning Kelvin probe microscopy, Raman spectroscopy, photoluminescence, and finite-element simulations. In our work, gate-tunable photocurrent in ZnO nanowires has been observed under optical excitation in the visible regime, which originates from the nanowire/substrate interface states. This gate tunability in the visible regime can be used to enhance the photon absorption efficiency, and suppress the undesirable visible-light photodetection in ZnO-based solar cells. The power conversion efficiency of CuInSe2/CdS core-shell nanowire solar cells has been investigated. The highest power conversion efficiency per unit area/volume is achieved with core diameter of 50 nm and the thinnest shell thickness. The existence of the optimal geometrical parameters is due to a combined effect of optical resonances and carrier transport/dynamics. Significant current crowding in two-dimensional black phosphorus field-effect transistors has been found, which has been significantly underestimated by the commonly used transmission-line model. This current crowding can lead to Joule heating close to the contacts. New van der Waals metal-semiconductor junctions have been mechanically constructed and systematically studied. The photocurrent on junction area has been demonstrated to originate from the photothermal effect rather than the photovoltaic effect. Our findings suggest that a reasonable control of interface/surface state properties can enable new and beneficial functionalities in nanostructures. We

  11. Mechanical and Electrical Properties of Aluminum/Epoxy Nanocomposites

    Science.gov (United States)

    Dong, Lina; Zhou, Wenying; Sui, Xuezhen; Wang, Zijun; Cai, Huiwu; Wu, Peng; Zhang, Yating; Zhou, Anning

    2016-11-01

    Surface-modified self-passivated aluminum (Al) nanoparticles were used for reinforcing epoxy (EP) resin, and the curing behavior, mechanical and electrical properties of the Al/EP nanocomposites were investigated. The incorporation of Al nanoparticles into EP significantly decreases the cure reaction enthalpy of the nancomposites, and the apparent activation energy of Al/EP systems is 64.96 kJ/mol. The coefficient of thermal expansion of the nanocomposites decreases with increasing the Al loading due to the strong interaction between the Al and the EP matrix. The storage modulus of the nanocomposites increases continuously with Al content, whereas, the glass transition temperature declines slightly. With increasing the Al content, the tensile modulus, flexural modulus and compressive modulus of the nanocomposites increase continuously compared with the neat one. The mechanical properties are improved by Al nanoparticles at low Al contents. The best overall dielectric and electrical performance are achieved about at 1 wt.% of Al concentration. The enhanced dielectric breakdown strength is mainly related to the insulating alumina shell on the surface of core Al and the strong interfacial interactions.

  12. Anomalous temperature dependence of the electrical resistivity of molten Sb

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using the d.c. four-probe method, the electrical resistivity of high-purity liquid Sb has been accurately measured as functions of temperature. It is observed that the resistivity of liquid Sb changes abnormally with increasing temperature, which is very different from that of simple liquid metals. Based on the reported structure factor at several temperatures, the results obtained in this work have been discussed and interpreted qualitatively according to Ziman theory. The analysis suggests that the existence of shortrange order structure near the melting point can account for the abnormal phenomenon observed in the resistivity of liquid Sb, in which semimetal-metal transaction takes place in the melting process. At the same time, the progress of the structure change of liquid Sb with temperature has also been pointed out.``

  13. Universal relation for size dependent thermodynamic properties of metallic nanoparticles.

    Science.gov (United States)

    Xiong, Shiyun; Qi, Weihong; Cheng, Yajuan; Huang, Baiyun; Wang, Mingpu; Li, Yejun

    2011-06-14

    The previous model on surface free energy has been extended to calculate size dependent thermodynamic properties (i.e., melting temperature, melting enthalpy, melting entropy, evaporation temperature, Curie temperature, Debye temperature and specific heat capacity) of nanoparticles. According to the quantitative calculation of size effects on the calculated thermodynamic properties, it is found that most thermodynamic properties of nanoparticles vary linearly with 1/D as a first approximation. In other words, the size dependent thermodynamic properties P(n) have the form of P(n) = P(b)(1 -K/D), in which P(b) is the corresponding bulk value and K is the material constant. This may be regarded as a scaling law for most of the size dependent thermodynamic properties for different materials. The present predictions are consistent literature values.

  14. Electrical transport properties of graphene nanowalls grown at low temperature using plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Zhao, Rong; Ahktar, Meysam; Alruqi, Adel; Dharmasena, Ruchira; Jasinski, Jacek B.; Thantirige, Rukshan M.; Sumanasekera, Gamini U.

    2017-05-01

    In this work, we report the electrical transport properties of uniform and vertically oriented graphene (graphene nanowalls) directly synthesized on multiple substrates including glass, Si/SiO2 wafers, and copper foils using radio-frequency plasma enhanced chemical vapor deposition (PECVD) with methane (CH4) as the precursor at relatively low temperatures. The temperature for optimum growth was established with the aid of transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. This approach offers means for low-cost graphene nanowalls growth on an arbitrary substrate with the added advantage of transfer-free device fabrication. The temperature dependence of the electrical transport properties (resistivity and thermopower) were studied in the temperature range, 30-300 K and analyzed with a combination of 2D-variable range hopping (VRH) and thermally activated (TA) conduction mechanisms. An anomalous temperature dependence of the thermopower was observed for all the samples and explained with a combination of a diffusion term having a linear temperature dependence plus a term with an inverse temperature dependence.

  15. Temperature Dependence of Electrical Resistance of Woven Melt-Infiltrated SiCf/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Appleby, Matthew P.; Morscher, Gregory N.; Zhu, Dongming

    2016-01-01

    Recent studies have successfully shown the use of electrical resistance (ER)measurements to monitor room temperature damage accumulation in SiC fiber reinforced SiC matrix composites (SiCf/SiC) Ceramic Matrix Composites (CMCs). In order to determine the feasibility of resistance monitoring at elevated temperatures, the present work investigates the temperature dependent electrical response of various MI (Melt Infiltrated)-CVI (Chemical Vapor Infiltrated) SiC/SiC composites containing Hi-Nicalon Type S, Tyranno ZMI and SA reinforcing fibers. Test were conducted using a commercially available isothermal testing apparatus as well as a novel, laser-based heating approach developed to more accurately simulate thermomechanical testing of CMCs. Secondly, a post-test inspection technique is demonstrated to show the effect of high-temperature exposure on electrical properties. Analysis was performed to determine the respective contribution of the fiber and matrix to the overall composite conductivity at elevated temperatures. It was concluded that because the silicon-rich matrix material dominates the electrical response at high temperature, ER monitoring would continue to be a feasible method for monitoring stress dependent matrix cracking of melt-infiltrated SiC/SiC composites under high temperature mechanical testing conditions. Finally, the effect of thermal gradients generated during localized heating of tensile coupons on overall electrical response of the composite is determined.

  16. Dielectric, electrical transport and magnetic properties of Er3+substituted nanocrystalline cobalt ferrite

    Science.gov (United States)

    Kakade, S. G.; Kambale, R. C.; Kolekar, Y. D.; Ramana, C. V.

    2016-11-01

    Erbium substituted cobalt ferrite (CoFe2-xErxO4; x=0.0-0.2, referred to CFEO) materials were synthesized by sol-gel auto-combustion method. The effect of erbium (Er3+) substitution on the crystal structure, dielectric, electrical transport and magnetic properties of cobalt ferrite is evaluated. CoFe2-xErxO4 ceramics exhibit the spinel cubic structure without any impurity phase for x≤0.10 whereas formation of the ErFeO3 orthoferrite secondary phase was observed for x≥0.15. All the CFEO samples demonstrate the typical hysteresis (M-H) behavior with a decrease in magnetization as a function of Er content due to weak superexchange interaction. The frequency (f) dependent dielectric constant (ε‧) revealed the usual dielectric dispersion. The ε‧-f dispersion (f=20 Hz to 1 MHz) fits to the modified Debye's function with more than one ion contributing to the relaxation. The relaxation time and spread factor derived are ∼10-4 s and ∼0.61(±0.04), respectively. Electrical and dielectric studies indicate that ε‧ increases and the dc electrical resistivity decreases as a function of Er content (x≤0.15). Complex impedance analyses confirm only the grain interior contribution to the conduction process. Temperature dependent electrical transport and room temperature ac conductivity (σac) analyses indicate the semiconducting nature and small polaron hopping.

  17. Electrical properties of the red blood cell membrane and immunohematological investigation

    Directory of Open Access Journals (Sweden)

    Heloise Pöckel Fernandes

    2011-01-01

    Full Text Available Hemagglutination is widely used in transfusion medicine and depends on several factors including antigens, antibodies, electrical properties of red blood cells and the environment of the reaction. Intermolecular forces are involved in agglutination with cell clumping occurring when the aggregation force is greater than the force of repulsion. Repulsive force is generated by negative charges on the red blood cell surface that occur due to the presence of the carboxyl group of sialic acids in the cell membrane; these charges create a repulsive electric zeta potential between cells. In transfusion services, specific solutions are used to improve hemagglutination, including enzymes that reduce the negative charge of red blood cells, LISS which improves the binding of antibodies to antigens and macromolecules that decrease the distance between erythrocytes. The specificity and sensitivity of immunohematological reactions depend directly on the appropriate use of these solutions. Knowledge of the electrical properties of red blood cells and of the action of enhancement solutions can contribute to the immunohematology practice in transfusion services.

  18. Electrical properties of polypropylene-based composites controlled by multilayered distribution of conductive particles.

    Science.gov (United States)

    Gao, Wanli; Zheng, Yu; Shen, Jiabin; Guo, Shaoyun

    2015-01-28

    Materials consisting of alternating layers of pure polypropylene (PP) and carbon black filled polypropylene (PPCB) were fabricated in this work. The electrical behaviors of the multilayered composites were investigated from two directions: (1) Parallel to interfaces. The confined layer space allowed for a more compact connection between CB particles, while the conductive pathways tended to be broken up with increasing number of layers leading to a distinct enhancement of the electrical resistivity due to the separation of insulated PP layers. (2) Vertical to interfaces. The alternating assemblies of insulated and conductive layers like a parallel-plate capacitor made the electrical conductivity become frequency dependent. Following the layer multiplication process, the dielectric permittivity was significantly enhanced due to the accumulation of electrical charges at interfaces. Thus, as a microwave was incident on the dielectric medium, the interfacial polarization made the main contribution to inherent dissipation of microwave energy, so that the absorbing peak became strengthened when the material had more layers. Furthermore, the layer interfaces in the multilayered system were also effective to inhibit the propagation of cracks in the stretching process, leading to a larger elongation at the break than that of the PP/CB conventional system, which provided a potential route to fabricate electrical materials with optimal mechanical properties.

  19. Electric near-field enhancing properties of a finite-size metal conical nano-tip.

    Science.gov (United States)

    Goncharenko, A V; Chang, Hung-Chih; Wang, Juen-Kai

    2007-01-01

    Finite-difference time-domain (FDTD) technique simulations are performed to study the near-field resonance properties of a silver conical nano-tip with a rounded end. Varying the tip geometry, we have computed the electric field distribution, as well as the electric field enhancement factor in the immediate vicinity of the tip apex. The aim of this study is to find optimal geometric parameters of the conical tip, such as its angle and length, in order to maximize the electric field enhancement factor. The increase of the tip length is shown to result in a redshift of the tip resonance wavelength. In addition, some subsidiary (non-dipole) peaks appear for relatively long tips. The peak enhancement values for the small-angle tips increase with the tip length while those for the large-angle ones decrease with it. At the same time, the dependencies of the field enhancement on the cone angle exhibit non-monotonic behavior. In other words, an optimal angle exists allowing one to maximize the electric near field. Finally, the effect of the supporting dielectric medium on the electric field near the tip apex is discussed. In the approximation used, the effect is shown to leave the main conclusions unchanged.

  20. Delay-Dependent Response in Weakly Electric Fish under Closed-Loop Pulse Stimulation.

    Science.gov (United States)

    Forlim, Caroline Garcia; Pinto, Reynaldo Daniel; Varona, Pablo; Rodríguez, Francisco B

    2015-01-01

    In this paper, we apply a real time activity-dependent protocol to study how freely swimming weakly electric fish produce and process the timing of their own electric signals. Specifically, we address this study in the elephant fish, Gnathonemus petersii, an animal that uses weak discharges to locate obstacles or food while navigating, as well as for electro-communication with conspecifics. To investigate how the inter pulse intervals vary in response to external stimuli, we compare the response to a simple closed-loop stimulation protocol and the signals generated without electrical stimulation. The activity-dependent stimulation protocol explores different stimulus delivery delays relative to the fish's own electric discharges. We show that there is a critical time delay in this closed-loop interaction, as the largest changes in inter pulse intervals occur when the stimulation delay is below 100 ms. We also discuss the implications of these findings in the context of information processing in weakly electric fish.

  1. Applying petrophysical models to radar travel time and electrical resistivity tomograms: Resolution-dependent limitations

    Science.gov (United States)

    Day-Lewis, F. D.; Singha, K.; Binley, A.M.

    2005-01-01

    Geophysical imaging has traditionally provided qualitative information about geologic structure; however, there is increasing interest in using petrophysical models to convert tomograms to quantitative estimates of hydrogeologic, mechanical, or geochemical parameters of interest (e.g., permeability, porosity, water content, and salinity). Unfortunately, petrophysical estimation based on tomograms is complicated by limited and variable image resolution, which depends on (1) measurement physics (e.g., electrical conduction or electromagnetic wave propagation), (2) parameterization and regularization, (3) measurement error, and (4) spatial variability. We present a framework to predict how core-scale relations between geophysical properties and hydrologic parameters are altered by the inversion, which produces smoothly varying pixel-scale estimates. We refer to this loss of information as "correlation loss." Our approach upscales the core-scale relation to the pixel scale using the model resolution matrix from the inversion, random field averaging, and spatial statistics of the geophysical property. Synthetic examples evaluate the utility of radar travel time tomography (RTT) and electrical-resistivity tomography (ERT) for estimating water content. This work provides (1) a framework to assess tomograms for geologic parameter estimation and (2) insights into the different patterns of correlation loss for ERT and RTT. Whereas ERT generally performs better near boreholes, RTT performs better in the interwell region. Application of petrophysical models to the tomograms in our examples would yield misleading estimates of water content. Although the examples presented illustrate the problem of correlation loss in the context of near-surface geophysical imaging, our results have clear implications for quantitative analysis of tomograms for diverse geoscience applications. Copyright 2005 by the American Geophysical Union.

  2. Evaluation of electric properties of cement mortars containing pozzolans

    Directory of Open Access Journals (Sweden)

    Cruz, J. M.

    2011-03-01

    Full Text Available In this paper the evolution of the microstructure of Portland cement mortar is analyzed, by using electrical impedance measurements. Cement mortars are compared without and with two pozzolanic substitutions: spent fluid catalytic cracking catalyst (FCC and metakaolin (MK. The measurement method is described and the model for analyzing the electrical impedance spectra is developed. Three electrical parameters are defined: electrical resistivity, capacitance exponent, and capacitive factor. The results show a significant increase in resistivity of the mortars with pozzolans after 7 days of curing, especially in mortars with MK. This increase is correlated with lime-fixing by the pozzolans. The capacitive properties evolve differently at early age, but reach the same values after 148 days. The electrical and mineralogical data show that the evolution of the microstructure in the mortar with MK starts before it does in the mortars with FCC and that the final microstructure becomes different.

    En este trabajo se analiza la microestructura de morteros de cemento Portland, mediante medidas de impedancia eléctrica. Se comparan morteros de cemento sin y con dos sustituciones puzolánicas: residuo de catalizador de craqueo catalítico (FCC y metacaolín (MK. Se describe el método de medida y se desarrolla el modelo de análisis de los espectros de impedancia eléctrica. Se definen tres parámetros eléctricos: resistividad eléctrica, exponente capacitivo, y factor capacitivo. Se observa un aumento importante de la resistividad de los morteros con puzolana a partir de los 7 días de curado, sobre todo en morteros con MK. Este aumento está correlacionado con la fijación de cal de las puzolanas. Las propiedades capacitivas son diferentes a edad temprana, pero se igualan a los 148 días. Los resultados eléctricos y mineralógicos muestran que la evolución microestructural comienza antes en los morteros con MK que con FCC y que la microestructura

  3. The uncertainties of magnetic properties measurements of electrical sheet steel

    CERN Document Server

    Ahlers, H

    2000-01-01

    In this work, uncertainties in measurements of magnetic properties of Epstein- and single-sheet samples have been determined according to the 'Guide To The Expression Of Uncertainty In Measurement', [International Organization for Standardization (1993)]. They were calculated for the results at predicted values of parameters taking into account the non-linear dependences. The measurement results and the uncertainties are calculated simultaneously by a computer program.

  4. Grain size dependent mechanical properties in nanophase materials

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, R.W. [Argonne National Lab., IL (United States); Fougere, G.E. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering

    1995-02-01

    It has become possible in recent years to synthesize metals and ceramics under well controlled conditions with constituent grain structures on a manometer size scale (below 100 nm). These new materials have mechanical properties that are strongly grain-size dependent and often significantly different than those of their coarser grained counterparts. Nanophase metals tend to become stronger and ceramics are more easily deformed as grain size is reduced. The observed mechanical property changes appear to be related primarily to grain size limitations and the large percentage of atoms in grain boundary environments. A brief overview of our present knowledge about the grain-size dependent mechanical properties of nanophase materials is presented.

  5. Calculation of electrical transport properties and electron entanglement in inhomogeneous quantum wires

    Directory of Open Access Journals (Sweden)

    A A Shokri

    2013-10-01

    Full Text Available In this paper, we have investigated the spin-dependent transport properties and electron entanglement in a mesoscopic system, which consists of two semi-infinite leads (as source and drain separated by a typical quantum wire with a given potential. The properties studied include current-voltage characteristic, electrical conductivity, Fano factor and shot noise, and concurrence. The calculations are based on the transfer matrix method within the effective mass approximation. Using the Landauer formalism and transmission coefficient, the dependence of the considered quantities on type of potential well, length and width of potential well, energy of transmitted electron, temperature and the voltage have been theoretically studied. Also, the effect of the above-mentioned factors has been investigated in the nanostructure. The application of the present results may be useful in designing spintronice devices.

  6. Effect of morphology on the electrical transport properties of polyaniline films for electronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Hardaker, S.S.; Eaiprasertsak, K.; Yon, J.; Gregory, R.V.; Tessema, G.X.

    1998-07-01

    Although it is well known that the oxidation state of polyaniline is an important characteristic, there are few reports of its influence on the development of morphology and electrical properties in fibers and films. In this work, differential scanning calorimetry is used in conjunction with measurements of temperature dependence of conductivity and thermoelectric power to elucidate the intimate relationship between structure and properties. By increasing the amount of chemical reduction of polyaniline solutions, films are repaired which exhibit a thermal transition between 300 and 385 C, indicative of melting. Increasing the chemical reduction also increases the conductivity of iodine doped films. The most reduced film exhibited a semiconductor transport mechanism, while the other films could be modeled with a quasi-one dimensional variable range hopping mechanism. The temperature dependence of conductivity also showed increasing order for increasing reduction, consistent with the DSC results.

  7. Magnetic and electrical properties of epitaxial GeMn

    Energy Technology Data Exchange (ETDEWEB)

    Ahlers, Stefan

    2009-01-15

    In this work, GeMn magnetic semiconductors will be investigated. The fabrication of GeMn thin films with Mn contents up to 11.7% was realised with molecular beam epitaxy. At a fabrication temperature of 60 C, the suppression of Mn{sub x}Ge{sub y} phases could reproducibly be obtained. Dislocation free epitaxy of diamond-lattice type GeMn thin films was observed. In all fabrication conditions where Mn{sub x}Ge{sub y} suppression was feasible, an inhomogeneous dispersion of Mn was observed in form of a self-assembly of nanometre sized, Mn rich regions in a Ge rich matrix. Each Mn rich region exhibits ferromagnetic coupling with high Curie temperatures exceeding, in part, room temperature. The local ferromagnetic ordering leads to the formation of large, spatially separated magnetic moments, which induce a superparamagnetic behaviour of the GeMn thin films. At low temperatures {<=} 20 K, remanent behaviour was found to emerge. X-ray absorption experiments revealed a similarity of the Mn incorporation in diamond-lattice type GeMn thin films and in the hexagonal lattice of the intermetallic Mn{sub 5}Ge{sub 3} phase, respectively. These tetrahedra represent building blocks of the Mn{sub 5}Ge{sub 3} unit cell. The incorporation of Mn{sub 5}Ge{sub 3} building blocks was found to be accompanied by local structural disorder. The electrical properties of GeMn thin films were addressed by transport measurements. It was shown that by using a n-type Ge substrate, a pn energy barrier between epilayers and substrate to suppress parallel substrate conduction paths can be introduced. With the pn barrier concept, first results on the magnetotransport behaviour of GeMn thin films were obtained. GeMn was found to be p-type, but of high resistivity. a series of GeMn thin films was fabricated, where intermetallic Mn{sub x}Ge{sub y} phase separation was supported in a controlled manner. Phase separation was found to result in the formation of partially coherent, nanometre sized Mn{sub 5

  8. Molybdenum Nitride Films: Crystal Structures, Synthesis, Mechanical, Electrical and Some Other Properties

    Directory of Open Access Journals (Sweden)

    Isabelle Jauberteau

    2015-10-01

    Full Text Available Among transition metal nitrides, molybdenum nitrides have been much less studied even though their mechanical properties as well as their electrical and catalytic properties make them very attractive for many applications. The δ-MoN phase of hexagonal structure is a potential candidate for an ultra-incompressible and hard material and can be compared with c-BN and diamond. The predicted superconducting temperature of the metastable MoN phase of NaCl-B1-type cubic structure is the highest of all refractory carbides and nitrides. The composition of molybdenum nitride films as well as the structures and properties depend on the parameters of the process used to deposit the films. They are also strongly correlated to the electronic structure and chemical bonding. An unusual mixture of metallic, covalent and ionic bonding is found in the stoichiometric compounds.

  9. SHI induced damage in electrical properties of silicon NPN BJTs

    Science.gov (United States)

    Kumar, M. Vinay; Kumar, Santhosh; Yashoda, T.; Krishnaveni, S.

    2016-05-01

    The investigation of radiation damage in Si microelectronic circuitry and devices are being carried out by various research groups globally. In particular the Si Bipolar junction transistors are very sensitive to high energetic radiation. In the present study, radiation response of NPN Bipolar junction transistor (2N3773) has been examined for 60 MeV B4+ ion. Key electrical properties like Gummel, dc current gain and capacitance - voltage (C-V) characteristics of 60 MeV B4+ ion irradiated transistor were studied before and after irradiation. Ion irradiation and subsequent electrical characterizations were performed at room temperature. Current voltage (I-V) measurements showed the increase in collector current for VBE ≤ 0.4 V as a function of fluence, which is due to B4+ ion induced surface leakage currents. Base current is observed to be more sensitive than collector current and gain appears to be degraded with ion fluence. Also, C-V measurements shows that both built in potential and doping concentration increased significantly after irradiation.

  10. Electrical properties and dielectric spectroscopy of Ar+ implanted polycarbonate

    Science.gov (United States)

    Chawla, Mahak; Shekhawat, Nidhi; Aggarwal, Sanjeev; Sharma, Annu; Nair, K. G. M.

    2015-05-01

    The aim of the present paper is to study the effect of argon ion implantation on electrical and dielectric properties of polycarbonate. Specimens were implanted with 130 keV Ar+ ions in the fluence ranging from 1×1014 to 1×1016 ions cm-2. The beam current used was ˜0.40 µA cm-2. The electrical conduction behaviour of virgin and Ar+ implanted polycarbonate specimens have been studied through current-voltage (I-V characteristic) measurements. It has been observed that after implantation conductivity increases with increasing ion fluence. The dielectric spectroscopy of these specimens has been done in the frequency range of 100 kHz-100 MHz. Relaxation processes were studied by Cole-Cole plot of complex permittivity (real part of complex permittivity, ɛ' vs. imaginary part of complex permittivity, ɛ″). The Cole-Cole plots have also been used to determine static dielectric constant (ɛs), optical dielectric constant (ɛ∞), spreading factor (α), average relaxation time (τ0) and molecular relaxation time (τ). The dielectric behaviour has been found to be significantly affected due to Ar+ implantation. The possible correlation between this behaviour and the changes induced by the implantation has been discussed.

  11. Heating Effects on Structural and Electrical Properties of Polyetherimide

    Directory of Open Access Journals (Sweden)

    Nissaf Mzabi

    2009-01-01

    Full Text Available Problem statement: Polyetherimide (PEI has several uses such as electrical insulation. It can undergo different constraints like heat or high voltage which influence its performances as insulator. In this study, the effects of heating on structural and electrical properties of polyetherimide (Ultem 1000 are studied. Approach: PEI samples were heated at different temperatures below the glass transition temperature (175, 190 and 205°C. Different complementary techniques were used to investigate structural alterations and dielectric relaxations. These are infrared (IR spectroscopy, Differential Scanning Calorimetry (DSC, Thermally Stimulated Depolarisation Current (TSDC technique and Dielectric Spectroscopy (DS. Results: Physical ageing was revealed in heated samples by DSC analysis. DS and TSDC results have shown that dipolar relaxations are affected by heating. The amount of relaxing dipoles decreases when the material is heated at 190°C. Conclusion/Recommendations: The heating of polyetherimide at 190°C leads to a stabilisation of charges in deeper energetic levels which influences the insulating character of the material.

  12. An Improvement in Electrical Properties of Asphalt Concrete

    Institute of Scientific and Technical Information of China (English)

    WU Shao-peng; MO Lian-tong; SHUI Zhong-he; XUAN Dong-xing; XUE Yong-jie; YANG Wen-feng

    2002-01-01

    Materials such as Koch AH - 70, basalt aggregate, limestone powder and graphite particles were used to prepare conductive asphalt concrete, which is a new type of multi functional concrete. The mix proportion by weight was shown as follows. Fineaggregates (2.36-4.75 mm):fine aggregates (< 2.36mm): limestone powder: asphalt = 120:240: 14:30. The content of added graphite particles ranged from 0% to 20% ( by the Special weight of asphalt concerte). A conductive asphalt concrete with a resistivity around 10-103·Ωm was obtained.attention was paid to the effects of graphite content, graphite physical-chemical properties, asphalt content and temperature on the resistivity. Furthermore, an attempt was made to develop an electrically conductive model for asphalt concrete.

  13. Note on electrical and thermodynamic properties of isolated horizons

    Science.gov (United States)

    Chen, Gerui; Wu, Xiaoning; Gao, Sijie

    2015-03-01

    The electrical laws and Carnot cycle of isolated horizons (IH) are investigated in this paper. We establish Ohm's law and Joule's law of isolated horizons and find that the conceptual picture of black holes (membrane paradigm) can also apply to this kind of quasilocal black holes. We also investigate the geometrical properties near nonrotating IHs and find that under the first-order approximation of r , there exist a Killing vector ∂∂u/ and a Hamiltonian conjugate to it, so this vector can be thought to be a physical observer. We calculate the energy as measured at infinity of a particle at rest outside a nonrotating IH, and we use this result to construct a reversible Carnot cycle with the isolated horizon as a cold reservoir, which confirms the thermodynamic nature of isolated horizons.

  14. A note on electrical and thermodynamic properties of Isolated Horizon

    CERN Document Server

    Chen, Gerui; Gao, Sijie

    2014-01-01

    The electrical laws and Carnot cycle of Isolated Horizon (IH) are investigated in this paper. We establish the Ohm's law and Joule's law of an Isolated Horizon, and find that the conceptual picture of black holes (Membrane Paradigm) can also apply to this kind of quasi-local black holes. We also investigate the geometrical properties near a non-rotating IH, and find that under the first-order approximation of r, there exist a Killing vector and a Hamiltonian conjugate to it, so this vector is a physical observer. We calculate the energy as measured at infinity of a particle at rest outside a non-rotating IH, and use this result to construct a reversible Carnot cycle with the Isolated Horizon as a cold reservoir, which confirms the thermodynamic nature of Isolated Horizon.

  15. Investigation of structural and electrical properties of mixed ferrite system

    Energy Technology Data Exchange (ETDEWEB)

    Astik, Nidhi M., E-mail: nidhiastik2002@gmail.com; Jha, Prafulla K., E-mail: prafullaj@yahoo.com [Department of Physics, Faculty of Science, The M. S. University of Baroda, Vadodara (Gujarat) (India)

    2015-05-15

    In the present work, structural and electrical properties of mixed ferrite systems are studied. As prepared compound of Co{sub 0.85}Ca{sub 0.15-y}Cd{sub y}Fe{sub 2}O{sub 4} (y=0.10, 0.15) is synthesized in polycrystalline form, using the stoichiometric mixture of oxides with conventional standard ceramic route with double sintering at 950°C and 1100°C and characterized by X-ray diffraction. The X-ray diffraction pattern confirms the presence of cubic (FCC) structure. The sharp intensified peaks in X-ray diffraction pattern clearly indicate the completeness of reaction.

  16. Optical Properties of Graphene in Magnetic and Electric fields

    CERN Document Server

    Lin, Chiun-Yan; Huang, Yao-Kung; Lin, Ming-Fa

    2016-01-01

    Optical properties of graphene are explored by using the generalized tight-binding model. The main features of spectral structures, the form, frequency, number and intensity, are greatly enriched by the complex relationship among the interlayer atomic interactions, the magnetic quantization and the Coulomb potential energy. Absorption spectra have the shoulders, asymmetric peaks and logarithmic peaks, coming from the band-edge states of parabolic dispersions, the constant-energy loops and the saddle points, respectively. The initial forbidden excitation region is only revealed in even-layer AA stacking systems. Optical gaps and special structures can be generated by an electric field. The delta-function-like structures in magneto-optical spectra, which present the single, twin and double peaks, are associated with the symmetric, asymmetric and splitting Landau-level energy spectra, respectively. The single peaks due to the non-tilted Dirac cones exhibit the nearly uniform intensity. The AAB stacking possesses...

  17. Nanofibrous Silver-Coated Polymeric Scaffolds with Tunable Electrical Properties

    Directory of Open Access Journals (Sweden)

    Adnan Memic

    2017-03-01

    Full Text Available Electrospun micro- and nanofibrous poly(glycerol sebacate-poly(ε-caprolactone (PGS-PCL substrates have been extensively used as scaffolds for engineered tissues due to their desirable mechanical properties and their tunable degradability. In this study, we fabricated micro/nanofibrous scaffolds from a PGS-PCL composite using a standard electrospinning approach and then coated them with silver (Ag using a custom radio frequency (RF sputtering method. The Ag coating formed an electrically conductive layer around the fibers and decreased the pore size. The thickness of the Ag coating could be controlled, thereby tailoring the conductivity of the substrate. The flexible, stretchable patches formed excellent conformal contact with surrounding tissues and possessed excellent pattern-substrate fidelity. In vitro studies confirmed the platform’s biocompatibility and biodegradability. Finally, the potential controlled release of the Ag coating from the composite fibrous scaffolds could be beneficial for many clinical applications.

  18. Method of determining an electrical property of a test sample

    DEFF Research Database (Denmark)

    2010-01-01

    A method of obtaining an electrical property of a test sample, comprising a non-conductive area and a conductive or semi-conductive test area, byperforming multiple measurements using a multi-point probe. The method comprising the steps of providing a magnetic field having field lines passing...... each tip, selecting one tip to be a current source positioned between conductive tips being used for determining a voltage in the test sample, performing a first measurement, moving the probe and performing a second measurement, calculating on the basis of the first and second measurement...... perpendicularly through the test area, bringing the probe into a first position on the test area, the conductive tips of the probe being in contact with the test area, determining a position for each tip relative to the boundary between the non- conductive area and the test area, determining distances between...

  19. Structural and electrical properties of In-implanted Ge

    Energy Technology Data Exchange (ETDEWEB)

    Feng, R., E-mail: ruixing.feng@anu.edu.au; Kremer, F.; Mirzaei, S.; Medling, S. A.; Ridgway, M. C. [Department of Electronic Materials Engineering, Research School of Physics and Engineering, Australian National University, Canberra, Australian Capital Territory 0200 (Australia); Sprouster, D. J. [Nuclear Science and Technology Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Decoster, S. [Instituut voor Kern-en Stralingsfysica, KU Leuven, 3001 Leuven (Belgium); Glover, C. J. [Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria 3168 (Australia); Russo, S. P. [Department of Applied Physics, School of Applied Sciences, RMIT University, Melbourne 3001 (Australia)

    2015-10-28

    We report on the effects of dopant concentration on the structural and electrical properties of In-implanted Ge. For In concentrations of ≤ 0.2 at. %, extended x-ray absorption fine structure and x-ray absorption near-edge structure measurements demonstrate that all In atoms occupy a substitutional lattice site while metallic In precipitates are apparent in transmission electron micrographs for In concentrations ≥0.6 at. %. Evidence of the formation of In-vacancy complexes deduced from extended x-ray absorption fine structure measurements is complimented by density functional theory simulations. Hall effect measurements of the conductivity, carrier density, and carrier mobility are then correlated with the substitutional In fraction.

  20. Relaxor behavior and electrical properties of high dielectric constant materials

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Several typical high dielectric constant materials are reviewed to study the electrical properties and relaxation mechanism. It is found that a Lorenz-type law can be used to describe the dielectric permit- tivity of either the normal ferroelectrics with or without diffuse phase transitions (DPT) or the typical ferroelectric relaxors. The ferroelectric DPT can be well described by just one fitting process using the Lorenz-type law, while the relaxor ferroelectric transition needs two independent fitting processes. The Lorenz-type law fails at the low temperature side of the dielectric maximum of a first-order ferroelectric phase transition. Above the transition temperature, the dielectric curves of all the studied materials can be well described by a Lorenz-type law.

  1. Relaxor behavior and electrical properties of high dielectric constant materials

    Institute of Scientific and Technical Information of China (English)

    FAN HuiQing; KE ShanMing

    2009-01-01

    Several typical high dielectric constant materials are reviewed to study the electrical properties and relaxation mechanism.It is found that a Lorenz-type law can be used to describe the dielectric permitUvity of either the normal ferroelectrics with or without diffuse phase transitions(DPT)or the typical ferroelectric relaxors.The ferroelectric DPT can be well described by just one fitting process using the Lorenz-type law,while the relaxor ferroelectric transition needs two independent fitting processes.The Lorenz-type law fails at the low temperature side of the dielectric maximum of a first-order ferroelectric phase transition.Above the transition temperature,the dielectric curves of all the studied materials can be well described by a Lorenz-type law.

  2. Electrical, optical and dielectric properties of HCl doped polyaniline nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Chutia, P.; Kumar, A., E-mail: ask@tezu.ernet.in

    2014-03-01

    In this report we have investigated the optical, electrical and dielectric properties of HCl doped polyaniline nanorods synthesized by the interfacial polymerization technique. High resolution transmission electron microscope (HRTEM) micrographs confirm the formation of nanorods. X-ray diffraction pattern shows the semicrystalline nature of polyaniline nanorods with a diameter distribution in the range of 10–22 nm. The chemical and electronic structures of the polyaniline nanorods are investigated by micro-Raman and UV–vis spectroscopy. Dielectric relaxation spectroscopy has been applied to study the dielectric permittivity, modulus formalism and ac conductivity as a function of frequency and temperature. The ac conductivity follows a power law with frequency. The variation of frequency exponent with temperature suggests that the correlated barrier hopping is the dominant charge transport mechanism. The existence of both polaron and bipolaron in the transport mechanism has been confirmed from the binding energy calculations.

  3. Effects of sodium on electrical properties in Cu{sub 2}ZnSnS{sub 4} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Akira; Yoshino, Kenji, E-mail: t0b114u@cc.miyazaki-u.ac.jp [Department of Applied Physics and Electronic Engineering, University of Miyazaki, Miyazaki 889-2192 (Japan); Miyake, Hideto [Department of Electrical and Electronic Engineering, Mie University, Tsu 514-8507 (Japan); Taniyama, Tomoyasu [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Kakimoto, Koichi [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Nose, Yoshitaro [Department of Materials Science and Engineering, Kyoto University, Kyoto 606-8501 (Japan); Scarpulla, Michael A. [Materials Science and Electrical Engineering Departments, University of Utah, Salt Lake City, Utah 84112 (United States)

    2014-04-14

    We have studied the effect of sodium on the electrical properties of Cu{sub 2}ZnSnS{sub 4} (CZTS) single crystal by using temperature dependence of Hall effect measurement. The sodium substitution on the cation site in CZTS is observed from the increasing of unit-cell size by powder X-ray diffraction. Sodium increases the effective hole concentration and makes the thermal activation energy smaller. The degree of compensation decreases with sodium incorporation, thus the hole mobility is enhanced. We revealed that sodium is important dopant in CZTS to control the electrical properties.

  4. Structural, optical and electrical properties of indium nitride polycrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.V.S. da, E-mail: marcus.sansil@gmail.com [Instituto de Fisica, UFBA, Campus Ondina, 40210-340, Salvador (Brazil); David, D.G.F.; Pepe, I.; Ferreira da Silva, A.; Almeida, J.S. de [Instituto de Fisica, UFBA, Campus Ondina, 40210-340, Salvador (Brazil); Gazoto, A.L. [Instituto de Fisica Gleb Wataghin (IFGW), UNICAMP, 13083-859, Campinas, SP (Brazil); Santos, A.O. dos [Instituto de Fisica Gleb Wataghin (IFGW), UNICAMP, 13083-859, Campinas, SP (Brazil); CCSST, Universidade Federal do Maranhao, 65900-410 Imperatriz, MA (Brazil); Cardoso, L.P.; Meneses, E.A. [Instituto de Fisica Gleb Wataghin (IFGW), UNICAMP, 13083-859, Campinas, SP (Brazil); Graybill, D.L. [75 Logan Street Brooklyn, NY 11208 (United States); Mertes, K.M. [Los Alamos National Laboratory, Los Alamos, NM 8754 (United States)

    2012-05-31

    The structural, optical and electrical properties of InN polycrystalline films on glass substrate are investigated by means of X-ray photoelectron spectroscopy, Raman scattering measurements, X-ray diffraction analysis, optical spectroscopy, and electrical measurements as a function of the inverse of temperature. The absorption edge for the films is most likely due to an impurity band formed by the presence of defects in the material. Such an impurity band, located at 1.6 eV extends itself to about 1.8 eV above the Fermi level, and it is attributed to nitrogen vacancies present in the material. The Raman scattering data also reveal the incorporation of oxygen in the InN films, leading to the formation of the In{sub 2}O{sub 3} amorphous phase during the process of sputtering. Additionally, the X-ray photoelectron spectroscopy of the valence band, which is highly desirable to the determination of the Fermi level, confirms the optical gap energy. Furthermore, the X-ray diffraction patterns of the thinner films present broader peaks, indicating high values for the strain between the film lattice and the glass substrate. Finally, first principles calculations are used to investigate the optical properties of InN and also to support the experimental findings. - Highlights: Black-Right-Pointing-Pointer InN thin films with different thicknesses and good quality were synthesized. Black-Right-Pointing-Pointer Semiconductor behavior and some contamination by In{sub 2}O{sub 3} were found. Black-Right-Pointing-Pointer The band gap was close to 1.8 eV compared to 0.7 eV found in pure InN. Black-Right-Pointing-Pointer The electronic structure for this material was determined.

  5. Incorporating residual temperature and specific humidity in predicting weather-dependent warm-season electricity consumption

    Science.gov (United States)

    Guan, Huade; Beecham, Simon; Xu, Hanqiu; Ingleton, Greg

    2017-02-01

    Climate warming and increasing variability challenges the electricity supply in warm seasons. A good quantitative representation of the relationship between warm-season electricity consumption and weather condition provides necessary information for long-term electricity planning and short-term electricity management. In this study, an extended version of cooling degree days (ECDD) is proposed for better characterisation of this relationship. The ECDD includes temperature, residual temperature and specific humidity effects. The residual temperature is introduced for the first time to reflect the building thermal inertia effect on electricity consumption. The study is based on the electricity consumption data of four multiple-street city blocks and three office buildings. It is found that the residual temperature effect is about 20% of the current-day temperature effect at the block scale, and increases with a large variation at the building scale. Investigation of this residual temperature effect provides insight to the influence of building designs and structures on electricity consumption. The specific humidity effect appears to be more important at the building scale than at the block scale. A building with high energy performance does not necessarily have low specific humidity dependence. The new ECDD better reflects the weather dependence of electricity consumption than the conventional CDD method.

  6. Effects of electric field on magnetic properties of MnxGe_{1-x} diluted magnetic semiconductors

    Science.gov (United States)

    Assefa, Gezahegn; Singh, P.

    2016-03-01

    We report the effect of external electric field (EEF) on the magnetic properties of MnxGe_{1-x}, diluted magnetic semiconductor. We present a Kondo Lattice Model type Hamiltonian with exchange coupling between localized spins, itinerant holes and the EEF. The magnetization, the dispersion and critical temperature (Tc) are calculated for different values of EEF parameters (α) using double time temperature-dependent Green function formalism. The enhancement of the (Tc) with the EEF is shown to be very distinct and is in agreement with recent experimental observation and much required for spintronics applications and devices.

  7. Electrical and Optical Properties of CeNi5 Nanoscale Films.

    Science.gov (United States)

    Todoran, Radu; Todoran, Daniela; Racolta, Dania; Szakács, Zsolt

    2016-12-01

    Rare earth compounds are interesting from both a theoretical point of view and for their applications. That is the reason why determining their optical and electrical properties deserves special attention. In this article, we present the conditions we obtained homogenous CeNi5 thin films of nanometer thicknesses. To achieve this goal, our method of choice was laser-induced vaporization, using short and modulated impulses, with electro-optical tuning for the quality factor. The layers that were deposited at a single laser burst had thicknesses between 1.5 and 2.5 nm, depending on the geometry of the experimental setup.Structural and compositional studies of the nanoscale films were made using XRD. The temperature dependence of electrical conductivity was also determined. The following optical properties of the specimens were computed using the Kramers-Krönig framework and discussed: absolute reflection and transmission coefficients for a single wavelength and relative ones for the wide UV-VIS-IR spectra, spectral dependence of the refractive index, and extinction coefficient as real and imaginary parts of the complex refractive index. The valence band studies were made with X-ray photoelectron spectroscopy. All these determinations were well correlated and permitted the evaluation of the energy densities of states in the deeper bands, near the Fermi energy, and at the surface states.

  8. Thermal dependence of electrical characteristics of micromachined silica microchannel plates

    Science.gov (United States)

    Tremsin, Anton S.; Vallerga, John V.; Siegmund, Oswald H. W.; Beetz, Charles P.; Boerstler, Robert W.

    2004-04-01

    Micromachined silica microchannel plates (MCPs) under development have a number of advantages over standard glass MCPs and open completely new possibilities in detector technologies. In this article we present the results of our studies on the thermal properties of silica microchannel plates (sMCPs). Similar to standard glass microchanel plates the resistance of silica MCPs was measured to change exponentially with temperature with a negative thermal coefficient of -0.036 per °C, somewhat larger than that of standard glass MCPs. The resistance also decreases linearly with the applied voltage, with the voltage coefficient of -3.1×10-4 V-1. With the knowledge of these two coefficients, our thermal model allows the calculation of the maximum voltage, which can be applied to a given MCP without inducing a thermal runaway. A typical 25 mm diam, 240 μm thick sMCP with 6 μm pores has to have the resistance larger than ˜30 MΩ to operate safely at voltages up to 800 V. With this model we can also calculate the time required for a given silica MCP to reach the point of thermal equilibrium after a voltage increase. We hope that the ongoing efforts on a proper modification of the sMCP semiconducting layer will lead to the production of new MCPs with a small negative or even a positive thermal coefficient, reducing the possibility of thermal runaways of low-resistance MCPs required for high count rate applications.

  9. Impedance spectroscopy analysis on electrical properties of serpentine at high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    ZHU; Maoxu; (

    2001-01-01

    [1]Stesky, R. M., Brace, W. F., Electrical conductivity of serpentinized rocks to 6 kilobar, J. Geophys. Res., 1973, 78 (32): 7614-7621.[2]Zhu Maoxu, Xie Hongsen, Experimental studies on electrical properties of materials in the earth's interior, Advancement in Geosciences (in Chinese), 1998, 13(5): 438-446.[3]Roberts, J. J., Tyburczy, J. A., Frequency dependent electrical properties of polycrystalline olivine compacts, J. Geophys. Res., 1991, 96 (B10): 16205-16222.[4]Roberts, J. J., Tyburczy, J. A., Frequency dependent electrical properties of minerals and partial-melts, Surv. Geophys., 1994, 15: 239-262.[5]Huebner, I. S., Dillenburg, R. G., Impedance spectra of hot, dry silicate minerals and rock: Qualitative interpretation of spectra, Amer. Mineral, 1995, 80: 46-64.[6]Kavner, A., Li, X-Y, Jeanloz, R., Electrical conductivity of a natural (Mg, Fe)SiO3 majorite garnet, Geophys. Res. Lett., 1995, 22 (22): 3103-3106.[7]Hicks, T. L., Secco, R., Dehydration and decomposition of pyrophyllite at high pressure: Electrical conductivity and X-ray diffraction studies to 5 Gpa, Can. J. Earth Sci., 1997, 34: 875-882.[8]Li, X-Y, Jeanloz, R., Effect of iron content on the electrical conductivity of perovskite and magnesiowustite assemblages at lower mantle condition, J. Geophys. Res., 1991, 96(B4): 6113-6120.[9]Xie Hongsen, Introduction to the Materials in the Earth's Interior (in Chinese), Beijing: Science Press, 1997, 42-53.[10] Tatsurmi, Y., Migration of fluid phase and genesis of basalt magmas in subduction zone, J. Geophys. Res., 1989, 94: 4697-4707.[11] Duba, A., Huenges, G., Nover, E. et al., Impedance of black shale from munsterland 1 borehole: An anomalously good conductor? Geophys. J., 1988, 94: 413-419.[12] Watanabe, T., Kurita, K., The relationship between electrical conductivity and melt fraction in a partially molten simple system: Archies's law behavior, Phys. Earth Planet Inter., 1993, 78: 9-17.[13] Macdonald

  10. Investigation of electrical properties of vacuum annealed titanium oxide containing ceramics

    Directory of Open Access Journals (Sweden)

    Agnese Pavlova

    2009-12-01

    Full Text Available Titanium oxide ceramics were prepared using extrusion process and subsequent thermal treatment in two stages – in air atmosphere at 1150°C and than in vacuum at temperatures between 1200 and 1350°C. Influence of thermal treatment conditions on microstructure and electrical properties (thermopower, conductivity of semiconductor and electron activation energy of obtained ceramics was investigated. It was confirmed that all samples treated in vacuum are n-type semiconductors. It was also found that the increase of temperature during sintering in vacuum leads to increased electrical conductivity, however, the highest thermopower values were obtained for samples thermally treated in vacuum at 1225°C. Electron activation energy (ΔE, calculated using dependence of conductivity of samples on temperature, was is in the range from 0.049 to 0.061 eV. The obtained products can be used as electrodes for water treatment technology based on photoelectrolysis.

  11. Electrical Characterization and Hydrogen Peroxide Sensing Properties of Gold/Nafion:Polypyrrole/MWCNTs Electrochemical Devices

    Science.gov (United States)

    Scandurra, Graziella; Arena, Antonella; Ciofi, Carmine; Saitta, Gaetano

    2013-01-01

    Electrochemical devices using as substrates copier grade transparency sheets are developed by using ion conducting Nafion: polypyrrole mixtures, deposited between gold bottom electrodes and upper electrodes based on Multi Walled Carbon Nanotubes (MWCNTs). The electrical properties of the Nafion:polypyrrole blends and of the gold/Nafion:polypyrrole/MWCNTs devices are investigated under dry conditions and in deionized water by means of frequency dependent impedance measurements and time domain electrical characterization. According to current-voltage measurements carried out in deionized water, the steady state current forms cycles characterized by redox peaks, the intensity and position of which reversibly change in response to H2O2, with a lower detection limit in the micromolar range. The sensitivity that is obtained is comparable with that of other electrochemical sensors that however, unlike our devices, require supporting electrolytes. PMID:23529125

  12. Tailoring of the electrical and thermal properties using ultra-short period non-symmetric superlattices

    Science.gov (United States)

    Komar, Paulina; Chávez-Ángel, Emigdio; Euler, Christoph; Balke, Benjamin; Kolb, Ute; Müller, Mathis M.; Kleebe, Hans-Joachim; Fecher, Gerhard H.; Jakob, Gerhard

    2016-10-01

    Thermoelectric modules based on half-Heusler compounds offer a cheap and clean way to create eco-friendly electrical energy from waste heat. Here we study the impact of the period composition on the electrical and thermal properties in non-symmetric superlattices, where the ratio of components varies according to (TiNiSn)n:(HfNiSn)6-n, and 0 ⩽ n ⩽ 6 unit cells. The thermal conductivity (κ) showed a strong dependence on the material content achieving a minimum value for n = 3, whereas the highest value of the figure of merit ZT was achieved for n = 4. The measured κ can be well modeled using non-symmetric strain relaxation applied to the model of the series of thermal resistances.

  13. Propagation in a waveguide with range-dependent seabed properties.

    Science.gov (United States)

    Holland, Charles W

    2010-11-01

    The ocean environment contains features affecting acoustic propagation that vary on a wide range of time and space scales. A significant body of work over recent decades has aimed at understanding the effects of water column spatial and temporal variability on acoustic propagation. Much less is understood about the impact of spatial variability of seabed properties on propagation, which is the focus of this study. Here, a simple, intuitive expression for propagation with range-dependent boundary properties and uniform water depth is derived. It is shown that incoherent range-dependent propagation depends upon the geometric mean of the seabed plane-wave reflection coefficient and the arithmetic mean of the cycle distance. Thus, only the spatial probability distributions (pdfs) of the sediment properties are required. Also, it is shown that the propagation over a range-dependent seabed tends to be controlled by the lossiest, not the hardest, sediments. Thus, range-dependence generally leads to higher propagation loss than would be expected, due for example to lossy sediment patches and/or nulls in the reflection coefficient. In a few instances, propagation over a range-dependent seabed can be calculated using range-independent sediment properties. The theory may be useful for other (non-oceanic) waveguides.

  14. Energy management of electric and hybrid vehicles dependent on powertrain configuration

    Science.gov (United States)

    Varga, Bogdan

    2012-06-01

    Electric and hybrid vehicles are going to become the most reliable source of transport for future years. The CO2 and NOx targets in Euro 6 normative puts the producers of vehicles in a dilemma, whether to adapt the internal combustion engines further, or to develop hybrid or electric power trains that are going to reach the pollution limit of the future norms or to go below that. Before acting a well-developed strategy in determining the optimum power flow has to be developed by producers; CRUISE software is a tool with the unique and special characteristics to determine the optimum in this highly important area. Whether electric vehicle, electric vehicle with range extender or a hybrid with CVT or planetary gearbox, the complexity of the mathematical modules remains the same, giving the developer the possibility to create complex functions and distinctive characteristics for each component of the vehicle. With such a powerful tool it becomes extremely easy to evaluate the energy flow in all directions, from electric machine to the battery, from electric machine to the power generator, and from the electric machine to the internal combustion engine. Applying to the (Electric Vehicle, Electric Vehicle with Range Extender, Hybrid vehicle with CVT, Hybrid vehicle with planetary gear set) the ECE-15 in a virtual environment (urban driving cycle) the simulation results show a different usage, rate of storage and efficiency concerning the energy, this being dependent of the power train configuration in most part.

  15. Effect of rapid thermal annealing on the structural and electrical properties of RF sputtered CCTO thin film

    Science.gov (United States)

    Tripathy, N.; Das, K. C.; Ghosh, S. P.; Bose, G.; Kar, J. P.

    2017-02-01

    CaCu3Ti4O12 (CCTO) thin films have been deposited by RF magnetron sputtering on silicon substrates at room temperature. As-deposited thin films were subjected to rapid thermal annealing (RTA) at different temperatures ranging from 850°C to 1000°C. XRD and capacitance - voltage studies indicate that the structural and electrical properties of CCTO thin film strongly depend upon the annealing temperature. XRD pattern of CCTO thin film annealed at 950°C revealed the polycrystalline nature with evolutions of microstructures. Electrical properties of the dielectric films were investigated by fabricating Al/CCTO/Si metal oxide semiconductor structure. Electrical properties were found to be deteriorated with increasing in annealing temperature.

  16. Effect of vacancy defect on electrical properties of chiral single-walled carbon nanotube under external electrical field

    Institute of Scientific and Technical Information of China (English)

    Luo Yu-Pin; Tien Li-Gan; Tsai Chuen-Horng; Lee Ming-Hsien; Li Feng-Yin

    2011-01-01

    Ab initio calculations demonstrated that the energy gap modulation of a chiral carbon nanotube with monovacancy defect can be achieved by applying a transverse electric field. The bandstructure of this defective carbon nanotube varying due to the external electric field is distinctly different from those of the perfect nanotube and defective zigzag nanotube. This variation in bandstructure strongly depends on not only the chirality of the nanotube and also the applied direction of the transverse electric field. A mechanism is proposed to explain the response of the local energy gap between the valence band maximum state and the local gap state under external electric field. Several potential applications of these phenomena are discussed.

  17. Synthesis, characterization and electrical properties of polyimines derived from selenophene

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, F.R.; Moreno, J.; Tagle, L.H.; East, G.A.; Radic, D. [Universidad Catolica de Chile, Santiago (Chile). Dept. de Quimica Organica

    1999-04-12

    Polyimines derived from 2,5-di-(oxophenyl)selenophene (I) were synthesized by reacting (I) with different diamines in suitable mixtures of solvents. All the diamines obtained were black and highly insoluble. The polymers were characterized by IR spectroscopy and elemental analysis. NMR was not intended in view of the insolubility of the compounds. Differential scanning calorimetry was utilized to determine the thermal parameters (T{sub g} and T{sub m}) of these polymers. Electrical properties of the doped (doping agents: iodine, antimony pentafluoride, aluminum and ferric chloride) and undoped polymers were determined at room temperature and atmospheric pressure. No variation in conductivity was observed when AlCl{sub 3} or FeCl{sub 3} was used as dopant. This behavior has been ascribed to the poor electron-acceptor properties of these salts, inhibiting thus the doping process. On the other hand, an important increase of the conductivity was attained when iodine was employed as doping agent; conversely, when the polymers were exposed to AsF{sub 5}, only a moderate increase in conductivity was observed for all the polymers surveyed. The increase in conductivity of these polymers after doping is due to the presence of nitrogen, a very electronegative element, in their structures that promotes the oxidation of the polymeric chain. (orig.) 35 refs.

  18. Polarity dependence of the electrical characteristics of Ag reflectors for high-power GaN-based light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae-Seong; Seong, Tae-Yeon, E-mail: tyseong@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Han, Jaecheon [Department of LED Business, Chip Development Group, LG Innotek, Paju 413-901 (Korea, Republic of); Ha, Jun-Seok [School of Applied Chemical Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2014-04-28

    We report on the polarity dependence of the electrical properties of Ag reflectors for high-power GaN-based light-emitting diodes. The (0001) c-plane samples become ohmic after annealing in air. However, the (11–22) semi-polar samples are non-ohmic after annealing, although the 300 °C-annealed sample shows the lowest contact resistivity. The X-ray photoemission spectroscopy (XPS) results show that the Ga 2p core level for the c-plane samples experiences larger shift toward the valence band than that for the semi-polar samples. The XPS depth profile results show that unlike the c-plane samples, the semi-polar samples contain some amounts of oxygen at the Ag/GaN interface regions. The outdiffusion of Ga atoms is far more significant in the c-plane samples than in the semi-polar samples, whereas the outdiffusion of N atoms is relatively less significant in the c-plane samples. On the basis of the electrical and XPS results, the polarity dependence of the electrical properties is described and discussed.

  19. Computational modeling of the dependence of kindling rate on network properties

    Science.gov (United States)

    Biswal, B.; Niranjan, B. R.; Ullal, G.; Dasgupta, C.

    2006-05-01

    The dependence of the rate of kindling on network properties, such as the number of neurons, number of stored memories, and the number of neurons used to store each memory, is studied through computer simulations of an appropriate neural network model for kindling of focal epilepsy. Simulations are performed for models of both chemical and electrical kindling. Larger and more complex networks are found to take longer time to kindle, as observed in experiments. The nature of the dependence of the kindling rate on network properties is somewhat different between the two types of kindling. A simple analysis of the process of chemical kindling is presented, which provides a semi-quantitative explanation of the behavior observed in our simulations. This analysis also shows that our main conclusions about the dependence of the kindling rate on the size and complexity of the network are independent of some of the assumptions made in our modeling.

  20. Frequency-dependent dynamic effective properties of porous materials

    Institute of Scientific and Technical Information of China (English)

    Peijun Wei; Zhuping Huang

    2005-01-01

    The frequency-dependent dynamic effective properties (phase velocity, attenuation and elastic modulus) of porous materials are studied numerically. The coherent plane longitudinal and shear wave equations, which are obtained by averaging on the multiple scattering fields, are used to evaluate the frequency-dependent dynamic effective properties of a porous material. It is found that the prediction of the dynamic effective properties includes the size effects of voids which are not included in most prediction of the traditional static effective properties. The prediction of the dynamic effective elastic modulus at a relatively low frequency range is compared with that of the traditional static effective elastic modulus, and the dynamic effective elastic modulus is found to be very close to the Hashin-Shtrikman upper bound.

  1. Electron-Positron Pair Production in Space- or Time-Dependent Electric Fields

    CERN Document Server

    Kleinert, Hagen; Xue, She-Sheng

    2008-01-01

    Treating the production of electron and positron pairs by a strong electric field from the vacuum as a quantum tunneling process we derive, in semiclassical approximation, a general expression for the pair production rate in a $z$-dependent electric field $E(z)$ pointing in the $z$-direction. We also allow for a smoothly varying magnetic field parallel to $E(z)$. The result is applied to a confined field $E(z)\

  2. Electrical and thermoelectric properties of different compositions of Ge–Se–In thin films

    Energy Technology Data Exchange (ETDEWEB)

    Aly, K.A., E-mail: kamalaly2001@gmail.com [Physics Department, Faculty of Science and Arts Khulais, University of Jeddah (Saudi Arabia); Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut (Egypt); Dahshan, A., E-mail: adahshan73@gmail.com [Department of Physics, Faculty of Science, Port Said University, Port Said (Egypt); Department of Physics, Faculty of Science for Girls, King Khalid University, Abha (Saudi Arabia); Abbady, Gh. [Department of Physics, Faculty of Science, Assuit University, Assuit (Egypt); Saddeek, Y. [Physics Department, Faculty of Science, Al-Azhar University, Assiut Branch, Assiut (Egypt)

    2016-09-15

    The effect of temperature in the range of 300–450 K and the indium content on the electrical and thermoelectric properties of Ge{sub 20}Se{sub 80−x}In{sub x} (0.0≤x≤24 at%) chalcogenide glassy thin films have been studied. From dc electrical and thermoelectric measurements, it was observed that the activation energies for electrical conductivity (ΔE) and for thermoelectric (ΔE{sub s}) decrease while the conductivity (σ) and Seebeck coefficient (S) increase upon introducing In into the Ge–Se glasses. In contrast to the behavior obtained with Bi or Pb doping, In incorporated in Ge–Se does not lead to a p-to n-type conduction inversion. The power factor (P) which is strongly depends on both of the Seebeck coefficient and the electrical conductivity. According to the obtained results, the Ge{sub 20}Se{sub 80−x}In{sub x} films can be considered potential candidates for incurring high action thermoelectric materials.

  3. Experimental evidence of tunable space-charge-layer-induced electrical properties of nanocrystalline ceria thin films.

    Science.gov (United States)

    Lee, Kyung-Ryul; Lee, Jong-Ho; Yoo, Han-Ill

    2013-10-07

    Fully dense nanocrystalline ceria films were successfully deposited on a MgO single crystal by pulsed laser deposition (PLD). The electrical conductivity of the nanocrystalline thin film was 20 times higher than that of the bulk sample. The activation energy of bulk ceria was 2.3 eV, whereas the activation energy of the nanocrystalline sample was only 1.2 eV. After post-annealing at 1273 K in which the grain size of the nanocrystalline thin film increased to ~400 nm, the electrical conductivity and activation energy of the film were changed similar to those of bulk. These unique electrical properties of the nano-crystalline thin-film can be attributed to the grain size effect, or more specifically, to the space charge layer (SCL) effect. Furthermore, the electrical conductivity of the nanocrystalline thin film became similar to that of the bulk in an extremely reducing atmosphere because of the unusual dependence of the SCL effect on the oxygen partial pressure.

  4. Improvement in electrical, thermal and mechanical properties of epoxy by filling carbon nanotube

    Directory of Open Access Journals (Sweden)

    2008-01-01

    Full Text Available In this study, electrical, thermal and mechanical properties of multi-walled carbon nanotubes (CNTs reinforced Epon 862 epoxy have been evaluated. Firstly, 0.1, 0.2, 0.3, and 0.4 wt% CNT were infused into epoxy through a high intensity ultrasonic liquid processor and then mixed with EpiCure curing agent W using a high speed mechanical agitator. Electric conductivity, dynamic mechanical analysis (DMA, three point bending tests and fracture tests were then performed on unfilled, CNT-filled epoxy to identify the loading effect on the properties of materials. Experimental results show significant improvement in electric conductivity. The resistivity of epoxy decreased from 1014 Ω•m of neat epoxy to 10 Ω•m with 0.4% CNT. The experimental results also indicate that the frequency dependent behavior of CNT/epoxy nanocomposite can be modeled by R-C circuit, permittivity of material increase with increasing of CNT content. DMA studies revealed that filling the carbon nanotube into epoxy can produce a 90% enhancement in storage modulus and a 17°C increase in Tg. Mechanical test results showed that modulus increased with higher CNT loading percentages, but the 0.3 wt% CNT-infusion system showed the maximum strength and fracture toughness enhancement. The decrease in strength and fracture toughness in 0.4% CNT/epoxy was attributed to poor dispersions of nanotubes in the composite.

  5. 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)

  6. Electric field dependence of the electron mobility in bulk wurtzite ZnO

    Indian Academy of Sciences (India)

    K Alfaramawi

    2014-12-01

    The electric field dependence of the electron mobility in bulk wurtzite zinc oxide (ZnO) material is studied. The low-field electron mobility is calculated as a function of doping concentration and lattice temperature. The results show that above nearly 50 K the electrical conduction is governed by activation through the bulk material and the conduction is then influenced by both lattice and impurity scattering mechanisms. The high-field characteristics are also considered. The transition between the low-field and high-field regions is specified. The negative differential mobility for bulk ZnO at room temperature is observed at electric fields above 280 kV/cm.

  7. Spin polarization dependence of quasiparticle properties in graphene

    OpenAIRE

    Qaiumzadeh, Alireza; Jahanbani, Kh.; Asgari, Reza

    2012-01-01

    We address spin polarization dependence of graphene's Fermi liquid properties quantitatively using a microscopic Random Phase Approximation theory in an interacting spin-polarized Dirac electron system. We show an enhancement of the minority-spin many-body velocity renormalization at fully spin polarization due to reduction in the electron density and consequently increase in the interaction between electrons near the Fermi surface. We also show that the spin dependence of the Fermi velocity ...

  8. Theory of temperature dependent phonon-renormalized properties

    OpenAIRE

    Monserrat, Bartomeu; Conduit, G. J.; Needs, R. J.

    2013-01-01

    We present a general harmonic theory for the temperature dependence of phonon-renormalized properties of solids. Firstly, we formulate a perturbation theory in phonon-phonon interactions to calculate the phonon renormalization of physical quantities. Secondly, we propose two new schemes for extrapolating phonon zero-point corrections from temperature dependent data that improve the accuracy by an order of magnitude compared to previous approaches. Finally, we consider the low-temperature limi...

  9. New insights into the electrical properties of ice and permafrost

    Science.gov (United States)

    Grimm, R. E.; Stillman, D.; MacGregor, J. A.; Dinwiddie, C. L.; McGinnis, R. N.; Hooper, D. M.

    2009-12-01

    The electrical properties of lab-created ice, salt hydrates, and ice-silicate mixtures were measured across a wide range of frequency (1 mHz-1 MHz) and temperature (180-273 K) and were compared to similar measurements of natural polar ice and permafrost. From these measurements we derived an updated, comprehensive view of charge movement within frozen materials, especially those with high impurity concentrations (soluble and/or insoluble). This new perspective will improve field mapping of subsurface ice and adsorbed water by dielectric spectroscopy (a.k.a. complex resistivity) and enable better prediction of radar attenuation in the cryosphere of the Earth and other icy bodies in the Solar System. Laboratory and natural ices with soluble impurities (salts and acids) in trace quantities have been extensively studied in the literature; we found that that an upper limit to the relaxation frequency corresponds to chloride saturation of the ice lattice at a few hundred uM. Higher initial salinity results in freezing-point depression and the formation of salt hydrates. The former can lead to electrically connected brine channels (see companion abstract by Grimm and Stillman, MR10), whose DC conductivity is well described by Archie’s Law. Higher dielectric relaxation frequencies in salt hydrates indicate defect concentrations up to a few orders of magnitude greater than impurity-saturated ice. Broadband measurements of a meteoric Antarctic ice core (Newall Glacier) revealed new electrical behavior not previously seen by classical tests. Although this sample’s bulk chlorinity was ~4 uM, it exhibited two dielectric relaxations; from Jaccard theory and our previous measurements, these relaxations are separable into ices with chlorinities of 2 and 30 uM. This double relaxation produces dielectric attenuation at 243 K that is an order of magnitude greater than would have been predicted if the bulk chlorinity value had been assumed. Further investigation is needed to

  10. Electrical and optical properties of nickel ferrite/polyaniline nanocomposite

    Directory of Open Access Journals (Sweden)

    M. Khairy

    2015-07-01

    Full Text Available Polyaniline–NiFe2O4 nanocomposites (PANI–NiFe2O4 with different contents of NiFe2O4 (2.5, 5 and 50 wt% were prepared via in situ chemical oxidation polymerization, while the nanoparticles nickel ferrite were synthesized by sol–gel method. The prepared samples were characterized using some techniques such as Fourier transforms infrared (FTIR, X-ray diffraction (XRD, scanning electron microscopy (SEM and thermogravimetric analysis (TGA. Moreover, the electrical conductivity and optical properties of the nanocomposites were investigated. Pure (PANI and the composites containing 2.5 and 5 wt% NiFe2O4 showed amorphous structures, while the one with 50 wt% NiFe2O4 showed a spinel crystalline structure. The SEM images of the composites showed different aggregations for the different nickel ferrite contents. FTIR spectra revealed to the formation of some interactions between the PANI macromolecule and the NiFe2O4 nanoparticles, while the thermal analyses indicated an increase in the composites stability for samples with higher NiFe2O4 nanoparticles contents. The electrical conductivity of PANI–NiFe2O4 nanocomposite was found to increase with the rise in NiFe2O4 nanoparticle content, probably due to the polaron/bipolaron formation. The optical absorption experiments illustrate direct transition with an energy band gap of Eg = 1.0 for PANI–NiFe2O4 nanocomposite.

  11. Characterization and electrical properties of chitosan for waste water treatment

    Science.gov (United States)

    Saengkaew, Phannee; Chantanachai, Kanittha; Cheewajaroen, Kulthawat; Nimsiri, Woraporn

    2016-05-01

    Chitosan extracted from shrimp shell waste was characterized in order to use for the industrial wastewater treatment. By XRF technique, the qualitative and semi-quantitative analyses of pure chitosan were performed with the relative compositions of Ca, Mg, Si, Fe, Al, and Na of 0.321%, 0.738%, 0.713%, 0.363%, 0.338%, and 3.858%, respectively. In the case of two types of the contaminated chitosan from the wastewater treatment before and after a process of a primary H2O2-treatment, the relative compositions of Ca, Mg, Si and Fe were obtained with an increasing of 0.356%, 1.321%, 1.536%, 0.451% and 0.406%, 1.105%, 1.178%, 0.591%, respectively. This shows that the suspended materials in the wastewater were absorbed by chitosan. By I-V Measurements, the across-through voltage of the pure chitosan disc was 0.245V±0.053 at the applied voltage of 17V, and resistance of 53.9MΩ ±10.3 at the applied voltage of 590V. After the utilization for the wastewater treatment, the across voltage of chitosan discs from two cases were 0.133V±0.047 and 0.223V±0.063, and the resistance of 122.8MΩ ±16.1 and 24.8MΩ ±5.1. The used chitosan has a lower conductivity because of a decreasing in the chitosan's electrical dipoles by combining with the suspended ions in the wastewater. Moreover, the adsorption efficiencies of chitosan for formaldehyde in the wastewater of two cases were 31.08% and 25.40%. In summary, chitosan is efficiently utilized in the wastewater treatment by absorption of the suspended materials and formaldehyde due to its molecular structure providing a good electrical property.

  12. Some Electrical Properties of Wild Mango Seed ad Mucuna ...

    African Journals Online (AJOL)

    PROF. O. E. OSUAGWU

    2013-06-01

    Jun 1, 2013 ... Electrical resistivity and conductivity of wild mango (irvingia ... that temperature and moisture contents had a more significant effect. ... flowering plants, consisting of approximately .... density to the electric field strength. In.

  13. Effect of gamma radiation on optical and electrical properties of tellurium dioxide thin films

    Indian Academy of Sciences (India)

    T K Maity; S L Sharma

    2008-11-01

    Gamma radiation induced changes in the optical and electrical properties of tellurium dioxide (TeO2) thin films, prepared by thermal evaporation, have been studied in detail. The optical characterization of the as-deposited thin films and that of the thin films exposed to various levels of gamma radiation dose clearly show that the optical bandgap decreases with increase in the gamma radiation dose up to a certain dose. At gamma radiation doses above this value, however, the optical bandgap has been found to increase. On the other hand, the current vs voltage plots for the as-deposited thin films and those for the thin films exposed to various levels of gamma radiation dose show that the current increases with the gamma radiation dose up to a certain dose and that the value of this particular dose depends upon the thickness of the film. The current has, however, been found to decrease with further increase in gamma radiation dose. The observed changes in both the optical and electrical properties indicate that TeO2 thin films can be used as the real time gamma radiation dosimeter up to a certain dose, a quantity that depends upon the thickness of the film.

  14. Electronic properties of bilayer graphenes strongly coupled to interlayer stacking and an external electric field

    Science.gov (United States)

    Park, Changwon; Ryu, Junga; Hong, Suklyun; Sumpter, Bobby; Kim, Gunn; Yoon, Mina

    2015-03-01

    In the design of bilayer graphene (BLG)-based switching devices, it is critical to understand the complex stacking structures observed experimentally and their impact on the overall electronic properties. Using a maximally localized Wannier function, a highly accurate tight-binding Hamiltonian based on density functional theory was constructed and the stacking-dependent evolution of BLGs electronic band structures and their response to an external electric field were systematically investigated. Although the crossing band structures remain at any stacking configurations (i.e., no energy gap opens), the wavefunction characteristics around the Fermi level can differ qualitatively for different stackings. This difference is conveyed to energy gap opening properties in the presence of an external electric field. We, for the first time, established a phase diagram summarizing the stacking-dependent electronic structures of BLG, separating metallic and semiconducting characteristics for a given external field. The research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

  15. Ion-beam-induced modifications in the structural and electrical properties of copper oxide selenite nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Pallavi, E-mail: prana.phy@gmail.com; Chauhan, R.P.

    2015-04-15

    Highlights: •Nanowires were synthesized via template-assisted electrodeposition method. •Copper oxide selenite nanowires were irradiated with 160 MeV, Ni{sup +12} ion beam. •XRD confirmed no change in phase of irradiated nanowires. •Electrical resistivity of nanowires was found to decrease with the ion fluence. -- Abstract: Irradiation with swift heavy ions (SHIs) with energy in the MeV range is a unique tool for engineering the properties of materials. In this context, the objective of the present work is to study the conduction of charge carriers in pre- and post-ion-irradiated semiconducting nanowires. Copper oxide selenite nanowires were synthesized using a template-assisted electrodeposition technique from an aqueous solution of 0.8 M CuSO{sub 4}·5H{sub 2}O and 8 mM SeO{sub 2}. The synthesized nanowires were observed to have a monoclinic structure with linear I–V characteristics (IVC). The effect of irradiation with 160 MeV Ni{sup +12} ions on the properties of the copper oxide selenite nanowires was investigated for fluences varying from 10{sup 11} to 10{sup 13} ions/cm{sup 2}. XRD spectra confirmed no change in the phase of the swift-heavy-ion-irradiated nanowires, but a modification in the orientation of the planes was observed that depended on the ion fluence. The electrical resistivity of the semiconducting nanowires also varied with the ion fluence. Simultaneous irradiation-induced modifications to the electro-chemical potential gradient and the granular properties of the material may have been the origin of the alteration in the structural and electrical properties of the nanowires.

  16. Photoluminescence as a Probe of the Electrical Charge Dependence of Gold Nanoparticles.

    Science.gov (United States)

    Obradovic, M; Di Vece, M; Asselberghs, I; Grandjean, D; Clays, K; Lievens, P

    2015-12-01

    Electro-optical switching can be achieved by changing the optical absorption of metal nanoparticles by adding or removing electrical charge, corresponding to increased, respectively, decreased electron density. In this work a different approach is taken by changing the photoluminescence properties as a function of electrical charge on gold nanoparticles. Whereas larger gold nanoparticles (diameter d = 5 and 10 nm), exhibiting a plasmon resonance peak in the absorption spectrum, were used to measure changes of the optical absorption spectrum upon electrical charging, for smaller gold nanoparticles (d = 2 and 5 nm) electrical charging was observed via changes of the photoluminescence. Increase and decrease in photoluminescence was observed at positive and negative applied potentials, respectively. The relation between changes of optical absorption and photoluminescence for the 5 nm particles by electrical charging provides information on the influence of the charge state on the electronic properties and therefore the optical transition probability. The reported observation that not only the optical absorption, but also the photoluminescence is affected by alteration of the electrical charge onto gold nanoparticles may open a new way towards electro-optical switching and bio-sensing.

  17. Effect of pH on the electrical properties and conducting mechanism of SnO2 nanoparticles

    Science.gov (United States)

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

    2017-03-01

    Semiconductor nanoparticles have attracted more interests because of their size-dependent optical and electrical properties.SnO2 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 SnO2 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 SnO2 nanoparticles is explained by means of the surface property of SnO2 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.

  18. 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.

  19. Electrical transport properties of single-layer WS2.

    Science.gov (United States)

    Ovchinnikov, Dmitry; Allain, Adrien; Huang, Ying-Sheng; Dumcenco, Dumitru; Kis, Andras

    2014-08-26

    We report on the fabrication of field-effect transistors based on single layers and bilayers of the semiconductor WS2 and the investigation of their electronic transport properties. We find that the doping level strongly depends on the device environment and that long in situ annealing drastically improves the contact transparency, allowing four-terminal measurements to be performed and the pristine properties of the material to be recovered. Our devices show n-type behavior with a high room-temperature on/off current ratio of ∼10(6). They show clear metallic behavior at high charge carrier densities and mobilities as high as ∼140 cm(2)/(V s) at low temperatures (above 300 cm(2)/(V s) in the case of bilayers). In the insulating regime, the devices exhibit variable-range hopping, with a localization length of about 2 nm that starts to increase as the Fermi level enters the conduction band. The promising electronic properties of WS2, comparable to those of single-layer MoS2 and WSe2, together with its strong spin-orbit coupling, make it interesting for future applications in electronic, optical, and valleytronic devices.

  20. Composition dependent room temperature structure, electric and magnetic properties in magnetoelectric Pb(Fe{sub 1/2}Nb{sub 1/2})O{sub 3}−Pb(Fe{sub 2/3}W{sub 1/3})O{sub 3} solid-solutions

    Energy Technology Data Exchange (ETDEWEB)

    Matteppanavar, Shidaling [Department of Physics, Jnanabharathi Campus, Bangalore University, Bangalore, 560056 (India); Rayaprol, Sudhindra [UGC-DAE-Consortium for Scientific Research, Mumbai Centre, B A R C Campus, Mumbai, 400085 (India); Angadi, Basavaraj, E-mail: brangadi@gmail.com [Department of Physics, Jnanabharathi Campus, Bangalore University, Bangalore, 560056 (India); Sahoo, Balaram [Materials Research Centre, Indian Institute of Science, Bangalore, 560012 (India)

    2016-08-25

    We report on the studies of room temperature (RT) crystal structure, electric and magnetic properties of (1−x) Pb(Fe{sub 1/2}Nb{sub 1/2})O{sub 3} – x Pb(Fe{sub 2/3}W{sub 1/3})O{sub 3} (PFN{sub 1−x} – PFW{sub x}) (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) solid solutions through the measurements of X-ray diffraction, FTIR, scanning electron microscopy (SEM), Neutron diffraction, Raman, Magnetic, Mössbauer and ferroelectric measurements. FTIR spectra showed two main perovskite related transmission bands. The SEM analysis shows an average grain size of 2 μm for all the solid solutions. Rietveld refinement was performed on RT X-ray diffraction (XRD) and neutron diffraction (ND), which reveals, the monoclinic phase for x = 0.0 with space group Cm and Cubic phase for x = 1.0 with space group Pm-3m. In other words, increasing x, the samples exhibit a gradual phase transition from monoclinic to cubic. In addition, the Raman spectroscopy corroborates the change in structural symmetry from monoclinic (Cm) to cubic (Pm-3m) on varying x. The coexistence of both monoclinic and cubic symmetries was observed between x = 0.2–0.8. Magnetic measurements shows that, the magnetic phase transition from paramagnetic to antiferromagnetic (AFM) was observed at or above RT for x = 0.6 and above. The magnetic structure was refined using the propagation vector k = (½, ½, ½) and structure was found to be G-type antiferromagnetic. Magnetic properties (M-H loops) shows, a weak ferromagnetic behaviour with antiferromagnetic ordering at RT. At RT, x = 0.0–0.6 the samples exhibits disordered paramagnetic property but weakly coupled with antiferromagnetic domains. But, x = 0.8 and 1.0 samples show antiferromagnetic and they are weakly coupled with paramagnetic domains. The temperature dependent magnetization (M(T)) confirms, the augmentation of Néel temperature (T{sub N}) from 155 K to 350 K on increasing x. Mössbauer spectroscopy confirms superparamagnetic nature with the presence of

  1. AlN Bandgap Temperature Dependence from its Optical Properties

    Science.gov (United States)

    2008-06-07

    AlN bandgap temperature dependence from its optical properties E. Silveira a,, J.A. Freitas b, S.B. Schujman c, L.J. Schowalter c a Depto. de Fisica ...range. The energy gap in semiconductors in general changes due to contributions from the electron–phonon interaction and due to the lattice thermal

  2. CONVERGENCE PROPERTIES OF THE DEPENDENT PRP CONJUGATE GRADIENT METHODS

    Institute of Scientific and Technical Information of China (English)

    Shujun LIAN; Changyu WANG; Lixia CAO

    2006-01-01

    In this paper, a new region of βκ with respect to βPRPκ is given. With two Armijo-type line searches, the authors investigate the global convergence properties of the dependent PRP conjugate gradient methods, which extend the global convergence results of PRP conjugate gradient method proved by Grippo and Lucidi (1997) and Dai and Yuan (2002).

  3. Process depending morphology and resulting physical properties of TPU

    Energy Technology Data Exchange (ETDEWEB)

    Frick, Achim, E-mail: achim.frick@hs-aalen.de; Spadaro, Marcel, E-mail: marcel.spadaro@hs-aalen.de [Institute of Polymer Science and Processing (iPSP), Aalen University (Germany)

    2015-12-17

    Thermoplastic polyurethane (TPU) is a rubber like material with outstanding properties, e.g. for seal applications. TPU basically provides high strength, low frictional behavior and excellent wear resistance. Though, due to segmented structure of TPU, which is composed of hard segments (HSs) and soft segments (SSs), physical properties depend strongly on the morphological arrangement of the phase separated HSs at a certain ratio of HSs to SSs. It is obvious that the TPU deforms differently depending on its bulk morphology. Basically, the morphology can either consist of HSs segregated into small domains, which are well dispersed in the SS matrix or of few strongly phase separated large size HS domains embedded in the SS matrix. The morphology development is hardly ruled by the melt processing conditions of the TPU. Depending on the morphology, TPU provides quite different physical properties with respect to strength, deformation behavior, thermal stability, creep resistance and tribological performance. The paper deals with the influence of important melt processing parameters, such as temperature, pressure and shear conditions, on the resulting physical properties tested by tensile and relaxation experiments. Furthermore the morphology is studied employing differential scanning calorimeter (DSC), transmission light microscopy (TLM), scanning electron beam microscopy (SEM) and transmission electron beam microscopy (TEM) investigations. Correlations between processing conditions and resulting TPU material properties are elaborated. Flow and shear simulations contribute to the understanding of thermal and flow induced morphology development.

  4. Study of structural, magnetic and electrical properties on Ho-substituted BiFeO3

    Science.gov (United States)

    Durga Rao, T.; Karthik, T.; Srinivas, Adiraj; Asthana, Saket

    2012-12-01

    The polycrystalline Bi1-xHoxFeO3 (x=0, 0.05, 0.1) compounds were synthesized by conventional solid-state route. Rietveld refinement revealed that all the compounds were stabilized in rhombohedral structure with R3c (IUCr No. 161) space group. Room temperature magnetic measurements revealed that Ho substitution induces ferromagnetism and improves the magnetic properties of BiFeO3. A competing ferro and anti-ferro magnetic interaction was observed in these compounds. Temperature variation of complex impedance studies revealed that electrical properties are improved with the Ho substitution. The ac conductivity found to obey universal power law and showed the negative temperature coefficient of resistance character. Correlated barrier hopping model (CBH) was employed to explain the frequency and temperature dependence of ac conductivity and the mechanism of transport in the material BFO and Ho substituted BFO. Density of states near Fermi level was calculated by using the ac conductivity data.

  5. Low temperature sintering of MgCuZn ferrite and its electrical and magnetic properties

    Indian Academy of Sciences (India)

    S R Murthy

    2001-08-01

    The low temperature sintering of MgCuZn ferrite was investigated using the usual ceramic method. The effect of Cu substitution on the properties of MgZn ferrites was also investigated and it was found that the densification of MgCuZn ferrite is dependent upon Cu concentration. The sintered ferrite with a density of 4.93 g/cm3 and electrical resistivity > 1011-cm was obtained for the ferrite with 12 mol% Cu at relatively low sintering temperature (910°C). The magnetic properties of the ferrites also improved by the Cu substitution. The chip inductors made of the ferrite fired at 910 C with 12 mol% Cu exhibited higher d.c. resistance. From these studies it is concluded that the good quality chip inductor can be obtained using the MgCuZn ferrites.

  6. Magnetization and electric transport properties of single-crystal MgB2 nanowires.

    Science.gov (United States)

    Wu, Cen-Shawn; Chang, Yu-Cheng; Chen, Weimeng; Chen, Chinping; Feng, Qingrong

    2012-11-23

    High quality single-crystal magnesium diboride (MgB(2)) nanowires with lengths exceeding 10 μm were successfully synthesized by hybrid physical chemical vapor deposition. The magnetization and electrical transport properties of single-crystal MgB(2) nanowires (NWs) were measured. The superconducting transition temperature of the NWs was 37 K, as confirmed by magnetization measurements. The disordered behavior of the nanowires was observed by four-terminal current-voltage characteristic measurements of an individual NW from T = 10 to 300 K. The temperature-dependent resistivity curves for seven NWs collapsed into a universal curve described by the variable range hopping model, showing intrinsic nonmetallic transport properties. This implies that the granular superconducting defect states are critical to the superconductivity of the individual MgB(2) NWs.

  7. The influence of stoichiometry on electrical properties of silicon carbide grown by physical vapor transport process

    Science.gov (United States)

    Li, Qiang

    The purposes of this thesis were to investigate the influence of the vapor phase stoichiometry in the ambient on electrical properties of silicon carbide grown by physical vapor transport (PVT) process in order to provide a better understanding of the nature of the compensation mechanisms in semi-insulating SiC crystals. Standard PVT and hydrogen-assisted PVT processes have been used to grow SiC single crystals. Chemical elemental analysis, contactless resistivity mapping (COREMA), temperature dependent Hall measurements (TDH), deep level transient spectroscopy (DLTS), and minority diffusion length measurements were performed to characterize the properties of SiC wafers. The nitrogen contamination, the net carrier concentrations, and the concentrations of the major deep traps in the undoped and nitrogen-doped SiC crystals were found to substantially decrease during the standard PVT growth when moving from seed to tail of the crystal. Addition of hydrogen to the growth ambient changed all the properties in the same direction. As a consequence of the doping and deep traps variations, the electrical properties including resistivity, Fermi energy, and minority carrier lifetime continuously changed during the growth. The results of the hydrogen-assisted PVT growth and the virtual reactor growth modeling indicated that the electrical properties change as a function of stoichiometry in the vapor phase, and the carbon transport efficiency can be enhanced by the reactions of hydrogen with the SiC charge material and the graphite parts of the crucible. Thermodynamic calculation of the vapor phase stoichiometry and the studies of the properties of H2-assisted PVT-grown crystals have shown that hydrogen can be used as a key factor controlling the vapor phase stoichiometry in the PVT process; in this manner the purity, electrical uniformities and the yield of the semi-insulating wafers can be improved to a great extent. The electron mobility values were found unusually low in

  8. Study of Optical and Electrical Properties of Organic Thin Films for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Jan Pospisil

    2015-09-01

    Full Text Available The paper deals with the study of optical, electrical and dielectric properties of thin film organic materials suitable for the preparation of optoelectronic devices (e.g. photodiodes, phototransistors, photovoltaic cells. As active layers palladium phthalocyanine (PdPc[t-Bu]4, fullerene (acceptor material, PCBM and their mixture (9:5 mass % were used. Thin films were prepared by two methods: by spin coating (Chemat technology Spin Coater and by material inkjet printing (Dimatix Materials Printer DMP-2800. UV-VIS spectroscopy and ellipsometry were used to study the optical properties. The paper also presents results of electrical and dielectric measurements. We found out that the properties of all structures prepared by spin coating depend on the rotational speed of spin coater, on the mode of solution casting (static, dynamic and in the case of material inkjet printing they are too much influenced by the substrate. Samples prepared on the substrate at 60 °C showed a photovoltaic effect with fill factor about 0.25 and the conversion efficiency about 0.2 %.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7278

  9. Study of Optical and Electrical Properties of Organic Thin Films for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Jan Pospisil

    2015-09-01

    Full Text Available The paper deals with the study of optical, electrical and dielectric properties of thin film organic materials suitable for the preparation of optoelectronic devices (e.g. photodiodes, phototransistors, photovoltaic cells. As active layers palladium phthalocyanine (PdPc[t-Bu]4, fullerene (acceptor material, PCBM and their mixture (9:5 mass % were used. Thin films were prepared by two methods: by spin coating (Chemat technology Spin Coater and by material inkjet printing (Dimatix Materials Printer DMP-2800. UV-VIS spectroscopy and ellipsometry were used to study the optical properties. The paper also presents results of electrical and dielectric measurements. We found out that the properties of all structures prepared by spin coating depend on the rotational speed of spin coater, on the mode of solution casting (static, dynamic and in the case of material inkjet printing they are too much influenced by the substrate. Samples prepared on the substrate at 60 °C showed a photovoltaic effect with fill factor about 0.25 and the conversion efficiency about 0.2 %.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7278

  10. Searching for Electrical Properties, Phenomena and Mechanisms in the Construction and Function of Chromosomes

    Directory of Open Access Journals (Sweden)

    Ivan Kanev

    2013-03-01

    Full Text Available Our studies reveal previously unidentified electrical properties of chromosomes: (1 chromosomes are amazingly similar in construction and function to electrical transformers; (2 chromosomes possess in their construction and function, components similar to those of electric generators, conductors, condensers, switches, and other components of electrical circuits; (3 chromosomes demonstrate in nano-scale level electromagnetic interactions, resonance, fusion and other phenomena similar to those described by equations in classical physics. These electrical properties and phenomena provide a possible explanation for unclear and poorly understood mechanisms in clinical genetics including: (a electrically based mechanisms responsible for breaks, translocations, fusions, and other chromosomal abnormalities associated with cancer, intellectual disability, infertility, pregnancy loss, Down syndrome, and other genetic disorders; (b electrically based mechanisms involved in crossing over, non-disjunction and other events during meiosis and mitosis; (c mechanisms demonstrating heterochromatin to be electrically active and genetically important.

  11. Effects of physical properties on electrical conductivity of compacted lateritic soil

    Institute of Scientific and Technical Information of China (English)

    Wei Bai; Lingwei Kong; Aiguo Guo

    2013-01-01

    Natural soils of various types have different electrical properties due to the composition, structure, water content, and temperature. In order to investigate the electrical properties of lateritic soil, electrical con-ductivity experiments have been conducted on a self-developed testing device. Test results show that the electrical conductivity of laterite increases with the increase of water content, degree of saturation and dry density. When the water content is below the optimum water content, the electrical conductivity of soils increases nonlinearly and the variation rate increases dramatically. However, when the water content, degree of saturation, or dry density increases to a certain value, the electrical conductivity tends to be a constant. In addition, soil electrical conductivity increases with the increase of temperature, and it is observed that the electrical conductivity decreases with the increase of the number of wetting-drying cycles.

  12. SEARCHING FOR ELECTRICAL PROPERTIES, PHENOMENA AND MECHANISMS IN THE CONSTRUCTION AND FUNCTION OF CHROMOSOMES

    Directory of Open Access Journals (Sweden)

    Ivan Kanev

    2013-03-01

    Full Text Available Our studies reveal previously unidentified electrical properties of chromosomes: (1 chromosomes are amazingly similar in construction and function to electrical transformers; (2 chromosomes possess in their construction and function, components similar to those of electric generators, conductors, condensers, switches, and other components of electrical circuits; (3 chromosomes demonstrate in nano-scale level electromagnetic interactions, resonance, fusion and other phenomena similar to those described by equations in classical physics. These electrical properties and phenomena provide a possible explanation for unclear and poorly understood mechanisms in clinical genetics including: (a electrically based mechanisms responsible for breaks, translocations, fusions, and other chromosomal abnormalities associated with cancer, intellectual disability, infertility, pregnancy loss, Down syndrome, and other genetic disorders; (b electrically based mechanisms involved in crossing over, non-disjunction and other events during meiosis and mitosis; (c mechanisms demonstrating heterochromatin to be electrically active and genetically important.

  13. Electrical properties and conduction mechanism of the NaMg4(PO4)3 compound

    Science.gov (United States)

    Karray, M.; Louati, B.; Guidara, K.; Gargouri, M.

    2016-07-01

    The NaMg4(PO4)3 phosphor was prepared by the conventional high-temperature solid-state reaction. The phase formation of the compound was confirmed by the powder X-ray diffraction. Electrical properties of the compound have been studied using complex impedance spectroscopy in the frequency range 209 Hz-1 MHz and temperature range 648-712 K. The AC conductivity for grain contribution was interpreted using the universal Jonscher's power law. The temperature dependence of frequency exponent s was investigated to understand the conduction mechanism in NaMg4(PO4)3 compound. The non-overlapping small polaron tunneling model can explain the temperature dependence of the frequency exponent, and it was a closely good model to describe the dominant conduction mechanism.

  14. Temperature Induced Stress Dependent Photoluminescence Properties of Nanocrystallite Zinc Oxide

    Directory of Open Access Journals (Sweden)

    V. Kumar

    2011-01-01

    Full Text Available In this paper, Temperature induced stress dependent structural, optical and photoluminescence properties of nanoscrysllites ZnO (nc-ZnO films are reported. It is seen that crystallite size, band gap and PL intensity of nc-ZnO are strongly dependent on stress. Large compressive stress has been observed at temperature 350-400 °C while minimum stress obtained at temperature 450 °C. A small amount of expensive stress is obtained at temperature 500 and 500 °C. The surface topography of the nc-ZnO films has been studied using atomic force microscopy. The optical band gap of nc-ZnO has been decreased from 3.25 to 3.23 eV as a function of temperature induced stress. The luminescence property is dependent on stress of nc-ZnO films.

  15. Electrical properties of liquid Cd-Te alloys

    Science.gov (United States)

    Moussa, A. Ben; Giordanengo, B.; Humbert, J. C.; Chaaba, H.; Bestandji, M.; Gasser, J. G.

    2000-12-01

    The electrical resistivity and the thermopower of liquid Cdx-Te1-x have been investigated experimentally as a function of temperature over the whole composition range. Due to the high melting point of Cd0.5Te0.5(1098 °C) and the low boiling points of cadmium (765 °C) and tellurium (990 °C), the measurements were difficult. Nevertheless, with a different experimental setup we were able to measure the resistivity and the thermopower from the liquidus up to 1200 °C. The resistivity shows a maximum at x=0.54 reaching a value of 13 000 μΩ cm at 1100 °C. A marked feature of liquid Cdx-Te1-x is that the thermopower varies rapidly from a positive value in the tellurium rich region to a negative value in the cadmium rich one around the equiatomic composition. The electronic properties, near this composition, were analyzed by using equations derived from the Kubo-Greenwood formula.

  16. Electric properties of Co substituted Ni-Zn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Ghodake, J.S. [Department of Physics, Solapur University, Solapur 413255, MS (India); Kambale, R.C., E-mail: rckambale@hotmail.co [Department of Physics, Shivaji University, Kolhapur 416004 (India); Salvi, S.V. [Department of Physics, Birla college, Kalyan, Mumbai, MS (India); Sawant, S.R. [Department of Electronics, Shivaji University, Kolhapur 416004 (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.co [Department of Physics, Solapur University, Solapur 413255, MS (India)

    2009-11-03

    Nanocrystalline Ni-Co-Zn ferrites have been synthesized by chemical co precipitation method, using oxalate precursors. The phase formation of the sintered ferrite was confirmed by X-ray diffraction study. The lattice parameter 'a' increases with the addition of Co{sup 2+} content in the Ni-Zn ferrites. The electrical resistivity (rho) of mixed Ni-Zn ferrites has been studied as a function of varying Co{sup 2+} compositions. The resistivity was found to increase with the addition Co content in the Ni-Zn ferrite matrix. The variation of dc resistivity as a function of temperature is almost linear up to the Curie temperature and thereafter a break occurs indicating a change of magnetic ordering from ferrimagnetism to paramagnetism. The values of activation energy in paramagnetic region are found to be greater than those in ferrimagnetic region, which suggests that the process of conduction is affected by the change in magnetic ordering. The dielectric properties were studied as a function of frequency by using an LCR precision meter bridge. It was observed that the dielectric constant (epsilon') and dielectric loss tangent (tan delta) decreases with the substitution of Co{sup 2+} content in the Ni-Zn ferrites.

  17. Structural and electrical properties in tungsten/tungsten oxide multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cacucci, Arnaud [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Avenue Alain Savary, BP47870, F-21078 DIJON Cedex (France); Potin, Valérie, E-mail: valerie.potin@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Avenue Alain Savary, BP47870, F-21078 DIJON Cedex (France); Imhoff, Luc [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université de Bourgogne, 9 Avenue Alain Savary, BP47870, F-21078 DIJON Cedex (France); Martin, Nicolas [Institut FEMTO-ST, UMR 6174 CNRS, Université de Franche-Comté, ENSMM, UTBM, 32 Avenue de l' observatoire, F-25044, BESANCON Cedex (France)

    2014-02-28

    Tungsten and tungsten oxide periodic nanometric multilayers have been deposited by DC reactive sputtering using the reactive gas pulsing process. Different pulsing periods have been used for each deposition to produce metal-oxide periodic alternations ranging from 3.3 to 71.5 nm. The morphology, crystallinity and chemical composition of these films have been investigated by transmission electron microscopy and energy-dispersive X-ray spectroscopy techniques. The produced multilayers exhibited an amorphous structure and the composition stability of WO{sub 3} sub-layers has been pointed out. Moreover, electrical properties have also been studied by the van der Pauw technique. It revealed a clear stability of resistivity versus temperature for almost all samples and an influence of the multilayered structure on the resistivity behavior. - Highlights: • W/WO{sub 3} multilayers with nanometric periods are produced by gas pulsing. • Multilayers are mainly amorphous and the oxide sub-layers composed of WO{sub 3}. • Crystallized inclusions of β-W and β-W{sub 3}O phases in metallic sub-layers • Metallic-like behavior with low temperature coefficient of resistance.

  18. OPEP: a tool for the optimal partitioning of electric properties.

    Science.gov (United States)

    Angyán, János G; Chipot, Christophe; Dehez, François; Hättig, Christof; Jansen, Georg; Millot, Claude

    2003-06-01

    OPEP is a suite of FORTRAN programs targeted at the optimal partitioning of molecular electric properties. It includes an interactive module for the construction of Cartesian grids of points, on which either the molecular electrostatic potential or the induction energy is mapped. The generation of distributed multipoles and polarizabilities is achieved using either the formalism of the normal equations of the least-squares problem, which restates the fitting procedure in terms of simple matrix operations, or a statistical approach, which provides a pictorial description of the distributed models of multipoles and polarizabilities, thereby allowing the pinpointing of pathological cases. Molecular symmetry is accounted for by means of local atomic frames, which are generated in an automated fashion. A Tcl/Tk graphical user interface wraps the suite of programs, thereby making OPEP a user-friendly package for building models of distributed multipoles and polarizabilities. OPEP is an open-source suite of programs distributed free of charge under the GNU general public license (GPL) at http://www.lctn.uhp-nancy.fr/Opep.

  19. Field-dependent molecular ionization and excitation energies: Implications for electrically insulating liquids

    Directory of Open Access Journals (Sweden)

    N. Davari

    2014-03-01

    Full Text Available The molecular ionization potential has a relatively strong electric-field dependence as compared to the excitation energies which has implications for electrical insulation since the excited states work as an energy sink emitting light in the UV/VIS region. At some threshold field, all the excited states of the molecule have vanished and the molecule is a two-state system with the ground state and the ionized state, which has been hypothesized as a possible origin of different streamer propagation modes. Constrained density-functional theory is used to calculate the field-dependent ionization potential of different types of molecules relevant for electrically insulating liquids. The low singlet-singlet excitation energies of each molecule have also been calculated using time-dependent density functional theory. It is shown that low-energy singlet-singlet excitation of the type n → π* (lone pair to unoccupied π* orbital has the ability to survive at higher fields. This type of excitation can for example be found in esters, diketones and many color dyes. For alkanes (as for example n-tridecane and cyclohexane on the other hand, all the excited states, in particular the σ → σ* excitations vanish in electric fields higher than 10 MV/cm. Further implications for the design of electrically insulating dielectric liquids based on the molecular ionization potential and excitation energies are discussed.

  20. The development of the time dependence of the nuclear EMP electric field

    Energy Technology Data Exchange (ETDEWEB)

    Eng, C

    2009-10-30

    The nuclear electromagnetic pulse (EMP) electric field calculated with the legacy code CHAP is compared with the field given by an integral solution of Maxwell's equations, also known as the Jefimenko equation, to aid our current understanding on the factors that affect the time dependence of the EMP. For a fair comparison the CHAP current density is used as a source in the Jefimenko equation. At first, the comparison is simplified by neglecting the conduction current and replacing the standard atmosphere with a constant density air slab. The simplicity of the resultant current density aids in determining the factors that affect the rise, peak and tail of the EMP electric field versus time. The three dimensional nature of the radiating source, i.e. sources off the line-of-sight, and the time dependence of the derivative of the current density with respect to time are found to play significant roles in shaping the EMP electric field time dependence. These results are found to hold even when the conduction current and the standard atmosphere are properly accounted for. Comparison of the CHAP electric field with the Jefimenko electric field offers a direct validation of the high-frequency/outgoing wave approximation.

  1. Magnetic field dependent polarizability and electric field dependent diamagnetic susceptibility of a donor in Si

    Science.gov (United States)

    Muthukrishnaveni, M.; Srinivasan, N.

    2016-09-01

    The polarizability and diamagnetic susceptibility values of a shallow donor in Si are computed. These values are obtained for the cases bar{E}allel bar{B} and bar{E} bot bar{B}. The anisotropy introduced by these perturbations are properly taken care of in the expressions derived for polarizability and magnetic susceptibility. Our results show that the numerical value of the contribution from electric field to diamagnetic susceptibility is several orders smaller than that of the magnetic field effect. Polarizability values are obtained in a magnetic field by two different methods. The polarizability values decrease as the intensity of magnetic field increases. Using the Clausius-Mossotti relation, the anisotropic values of the refractive indices for different magnetic fields are estimated.

  2. Process dependent thermoelectric properties of EDTA assisted bismuth telluride

    Science.gov (United States)

    Kulsi, Chiranjit; Kargupta, Kajari; Banerjee, Dipali

    2016-04-01

    Comparison between the structure and thermoelectric properties of EDTA (Ethylene-diamine-tetra-acetic acid) assisted bismuth telluride prepared by electrochemical deposition and hydrothermal route is reported in the present work. The prepared samples have been structurally characterized by high resolution X-ray diffraction spectra (HRXRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopic images (HRTEM). Crystallite size and strain have been determined from Williamson-Hall plot of XRD which is in conformity with TEM images. Measurement of transport properties show sample in the pellet form (S1) prepared via hydrothermal route has higher value of thermoelectric power (S) than the electrodeposited film (S2). But due to a substantial increase in the electrical conductivity (σ) of the film (S2) over the pellet (S1), the power factor and the figure of merit is higher for sample S2 than the sample S1 at room temperature.

  3. Effect of Direct Electric Current on the Cell Surface Properties of Phenol-Degrading Bacteria

    OpenAIRE

    Luo, Qishi; Wang, Hui; Zhang, Xihui; Qian, Yi

    2005-01-01

    The change in cell surface properties in the presence of electric currents is of critical concern when the potential to manipulate bacterial movement with electric fields is evaluated. In this study, the effects of different direct electric currents on the cell surface properties involved in bacterial adhesion were investigated by using a mixed phenol-degrading bacterial culture in the exponential growth phase. The traits investigated were surface hydrophobicity (measured by adherence to n-oc...

  4. Vibrational corrections for some electric and magnetic properties of H2, N2, HF, and CO

    Science.gov (United States)

    Bishop, David M.; Cybulski, sławomir M.

    1994-08-01

    The effects of vibration on certain electric and magnetic properties of H2, N2, HF, and CO are reported. These properties include electric field gradients, generalized Sternheimer shielding constants, electric-field-gradient polarizabilities, nuclear shielding constants, and shielding polarizabilities. The calculations were based on both electron correlated and uncorrelated methods. Pure vibrational effects, where appropriate, were investigated as well as conventional vibrational averaging. It is found that in many cases vibration plays a very significant role.

  5. Electric field dependence of hybridized gap in InAs/GaSb quantum well system

    Science.gov (United States)

    Ruan, Jiufu; Wei, Xiangfei; Wang, Weiyang

    2017-02-01

    We demonstrate theoretically that exchange interaction induced by electron-hole scattering via Coulomb interaction can cause a hybridized gap in InAs/GaSb based type II and broken-gap quantum wells. The hybridized energy spectra are obtained analytically at the low temperature and long wave limits. An electric field depended hybridized gap about 4 meV opens at the anti-crossing points of the hybridized energy spectra, in accordance with experimental measurements. The hybridized gap varies linearly with the gate electric voltage due to the fact that the electric field can change the exchange self-energy by tuning the overlap of the wavefunctions and the Fermi energy. Our theoretical results can give a deep insight of the origin of the hybridized gap and provide a simple way to determine the value and the position of the hybridized gap in the presence of the gate electric voltage.

  6. Effects of Oxide-Modified Spherical ZnO on Electrical Properties of Ag/ZnO Electrical Contact Material

    Science.gov (United States)

    Wei, Zhijun; Zhang, Lingjie; Shen, Tao; Qiao, Zhengyang; Yang, Hui; Fan, Xianping; Chen, Lawson

    2016-09-01

    Silver-zinc oxide (Ag/ZnO) electrical contact material is widely used as contacts of the medium duty switching devices. Effects of modified ZnO on properties of Ag/ZnO electrical contact material were investigated in this work. NiO and CuO were introduced to modify spherical ZnO by a chemical solution nano-coating method. Ag/ZnO contacts prepared using the modified spherical ZnO were produced by powder metallurgy (PM) method in a muffle furnace in temperature ranges from 750 to 900 °C. Results show that electrical conductivity, stability of relative density, and Vickers' hardness of Ag/ZnO electrical contact material can be improved by the addition of NiO because of the formation of NiO solid solution Zn0.2Ni0.8O. The addition of CuO to Ag/ZnO electrical contact material makes arcing energy and mass loss lower. Since this is attractive for a longer service life, using NiO and CuO co-modified ZnO as a second phase may be a promising way to improve properties of Ag/ZnO electrical contact material. Hence, the presented results could also be useful for the design of a new Ag/ZnO electrical contact material.

  7. 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

  8. Evolution of Arbitrary States under Fock-Darwin Hamiltonian and a Time-Dependent Electric Field

    Institute of Scientific and Technical Information of China (English)

    徐晓飞; 杨涛; 翟智远; 潘孝胤

    2012-01-01

    The method of path integral is employed to calculate the time evolution of the eigenstates of a charged particle under the Fock-Darwin (FD) Hamiltonian subjected to a time-dependent electric field in the plane of the system. An exact analytical expression is established for the evolution of the eigenstates. This result then provides a general solution to the time-dependent Schrodinger equation.

  9. Nonlinear Effects of the Magnetotail Particle Motion in Time—dependent Electric Field

    Institute of Scientific and Technical Information of China (English)

    QiugangZONG; SuiyanFU; 等

    1996-01-01

    The Motion of charged particle in magnetotail-like reversal field with time dependent electric field is studied analytically and numerically using a test particle approach.Variations in the solar wind magnetic and/or velocity can induce a time-dependent electric field in the magnetotail.Interaction of the magnetotail particles with this electric field can give rise to stochasticity.Energy coupling from the field to the plasma is due to stochastic motion of the particles and is termed “Stochastic heating” or “stochastic acceleration”,The stochasticity can lead to heating of the plasma and to strong particle acceleration.The process can provide an explanation to the difference between ion and electron temperatures in the plasma sheet.

  10. Common long-range dependence in a panel of hourly Nord Pool electricity prices and loads

    DEFF Research Database (Denmark)

    Ergemen, Yunus Emre; Haldrup, Niels; Rodríguez-Caballero, Carlos Vladimir

    of the underlying production technology and because the demand is more volatile than the supply, equilibrium prices and loads are argued to identify the periodic power supply curve. The estimated supply elasticities are estimated from fractionally co-integrated relations and range between 0.5 and 1......Equilibrium electricity spot prices and loads are often determined simultaneously in a day-ahead auction market for each hour of the subsequent day. Hence daily observations of hourly prices take the form of a periodic panel rather than a time series of hourly observations. We consider novel panel...... data approaches to analyse the time series and the cross-sectional dependence of hourly Nord Pool electricity spot prices and loads for the period 2000-2013. Hourly electricity prices and loads data are characterized by strong serial long-range dependence in the time series dimension in addition...

  11. Epitaxial growth and electrical transport properties of La0.5Sr0.5CoO3 thin films prepared by pulsed laser deposition

    Institute of Scientific and Technical Information of China (English)

    李美亚; 熊光成; 王忠烈; 范守善; 赵清太; 林揆训

    1999-01-01

    Epitaxial growth of the La0.5Sr0.5CoO3(LSCO) thin films has been realized on LaAlO3, SrTiO3 and MgO substrates by pulsed laser deposition. The epitaxial growth behavior and the electrical transport properties of these films were studied systematically. The temperature dependencies of the resistivity of the film have been determined. Studies indicate that close dependencies exist between the crystal structures and the electrical transport properties of the epitaxial LSCO films, and that the epitaxial thin films are of low resistivity and metallic conductive features. The epitaxial films deposited on the LaAlO3 substrates at about 700℃ possess the optimal properties compared with the others. Discussions of the dependencies and the mechanisms of the epitaxial structures on the electrical transport properties of the LSCO films have been made.

  12. Electrical transport and thermoelectric properties of AgPb10SbTe12 prepared by high pressure method

    Indian Academy of Sciences (India)

    Taichao Su; Hongyu Zhu; Xiaolei Li; Shangsheng Li; Le Deng; Shizhao Zheng; Hongan Ma; Xiaopeng Jia

    2011-10-01

    Thermoelectric material, Ag1−PbSbTe+2 ( = 0.2, = 10), have been successfully prepared by high pressure method. The pressure-dependent electrical transport and thermoelectric properties of Ag0.8Pb10SbTe12 were studied at room temperature. Electrical resistivity and Seebeck coefficient decreases with an increase of synthetic pressure. Thermal conductivities are nearly constant when the pressure is lower than 4 GPa. The carrier concentrations of Ag0.8Pb10SbTe12 were tuned by more than a factor of 100 through changing of synthetic pressure. These results indicate that high pressure technique provides a viable and controllable way of tuning the electrical transport properties for AgPbSbTe+2.

  13. Dislocation structures and electrical conduction properties of low angle tilt grain boundaries in LiNbO3

    Science.gov (United States)

    Furushima, Yuho; Nakamura, Atsutomo; Tochigi, Eita; Ikuhara, Yuichi; Toyoura, Kazuaki; Matsunaga, Katsuyuki

    2016-10-01

    Dislocations in crystalline materials constitute unique, atomic-scale, one-dimensional structure and have a potential to induce peculiar physical properties that are not found in the bulk. In this study, we fabricated LiNbO3 bicrystals with low angle tilt grain boundaries and investigated the relationship between the atomic structure of the boundary dislocations and their electrical conduction properties. Observations by using transmission electron microscopy revealed that dislocation structures at the (0001) low angle tilt grain boundaries depend on the tilt angle of the boundaries. Specifically, the characteristic dislocation structures with a large Burgers vector were formed in the boundary with the tilt angle of 2°. It is noteworthy that only the grain boundary of 2° exhibits distinct electrical conductivity after reduction treatment, although LiNbO3 is originally insulating. This unique electrical conductivity is suggested to be due to the characteristic dislocation structures with a large Burgers vector.

  14. Effect of annealing prior to cold rolling on magnetic and mechanical properties of low carbon non-oriented electrical steels

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez-Castaneda, E.J., E-mail: emmanuel.gutierrez@yahoo.com.mx [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (CINVESTAV-IPN), Department of Metallurgical Engineering and Materials Science, Carretera Saltillo-Monterrey, Km 13.5, 25900 Ramos Arizpe, Coahuila, P.O. Box 663, Saltillo Coahuila, 25000 (Mexico); Salinas-Rodriguez, A., E-mail: armando.salinas@cinvestav.edu.mx [Centro de Investigacion y de Estudios Avanzados del Instituto Politecnico Nacional (CINVESTAV-IPN), Department of Metallurgical Engineering and Materials Science, Carretera Saltillo-Monterrey, Km 13.5, 25900 Ramos Arizpe, Coahuila, P.O. Box 663, Saltillo Coahuila, 25000 (Mexico)

    2011-10-15

    The effects of annealing prior to cold rolling on the microstructure, magnetic and mechanical properties of low-C grain non-oriented (GNO) electrical steels have been investigated. The grain structure of hot-rolled electrical steel strips is modified by annealing at temperatures between 700 and 1050 deg. C. Annealing at temperatures less than the ferrite to austenite+ferrite transformation temperature on heating (Ac{sub 1}) causes a marginal effect on the grain size. However, annealing in the intercritical region at temperatures between Ac{sub 1} and Ac{sub 3} (the ferrite+austenite to austenite transformation temperature on heating) causes rapid decarburization and development of large columnar ferrite grains free of carbide particles. This microstructure leads, after cold rolling and a fast annealing treatment, to carbide free, large ferrite grain microstructures with magnetic and mechanical properties superior to those observed typically in the same steel in the industrially fully processed condition. These results are attributed to the increment in grain size and to the {l_brace}1 0 0{r_brace} fiber texture developed during the final annealing at temperatures up to 850 deg. C. Annealing at higher temperatures, T>Ac{sub 3}, results in a strong {l_brace}1 1 1{r_brace} fiber texture and an increase of the quantity of second phase particles present in the microstructure, which lead to a negative effect on the final properties. The results suggest that annealing prior to cold rolling offers an attractive alternative processing route for the manufacture of fully processed low C GNO electrical steels strips. - Highlights: > Electrical steels are produced by an alternative processing route. > Annealing of the hot rolled electrical steel strips causes rapid decarburization. > Development of the <1 0 0>//ND texture results in better magnetic properties. > Magnetic properties of electrical steels depend on the grain size and texture. > Second phase particles and grain

  15. Electrical properties of foamed polypropylene/carbon black composites

    Science.gov (United States)

    Iliev, M.; Kotzev, G.; Vulchev, V.

    2016-02-01

    Polypropylene composites containing carbon black fillers were produced by vibration assisted extrusion process. Solid (unfoamed) composite samples were molded by conventional injection molding method, while structural foams were molded by a low pressure process. The foamed samples were evidenced to have a solid skin-foamed core structure which main parameters were found to depend on the quantity of material injected in the mold. The average bubbles' sizes and their distribution were investigated by scanning electron microscopy. It is established that the conductivity of the foamed samples gradually decreases when reducing the sample density. Nevertheless, the conductivity is found to be lower than the conductivity of the unfoamed samples both being of the same order. The flexural properties of the composites were studied and the results were discussed in the context of the structure parameters of the foamed samples.

  16. Thermoreversible gels of polyaniline: Viscoelastic and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Ikkala, O.T.; Vikki, T.; Ruokolainen, J.; Hiekkataipale, P.; Passiniemi, P.; Maekelae, T.; Isotalo, H.

    1998-07-01

    The authors demonstrate that polyaniline (PANI) dissolved in dodecyl benzene sulphonic acid (DBSA) shows thermoreversible gelation. The dissolution has been performed in formic acid which allows particle-free complexes according to optical microscopy. Below the gelation temperature the materials are rubber-elastic in compression experiments, the storage modulus G{prime} does not essentially depend on frequency, and the samples are electronically conductive. Above the gelation temperature, G{prime} indicates flow-like behavior and drastically lower ionic conductivity is observed. These results suggest reversible, i.e., fusible, network formation. The properties are compared with gels consisting of camphor sulphonic acid (CSA) doped PANI dissolved in m-cresol which are poorly thermoreversible.

  17. The Environmental Dependence of Galaxy Properties at z=2

    CERN Document Server

    Tanaka, Masayuki; Venemans, Bram; Kurk, Jaron

    2010-01-01

    We report on the environmental dependence of galaxy properties at z=2.15. We construct multi-band photometric data sets in the (proto-)cluster PKS1138-26 field and in the GOODS field. We then fit spectral energy distributions of the galaxies with model templates generated with the latest stellar population synthesis code and derive physical properties of galaxies from the fits. To quantify the environmental dependence of galaxy properties, a special care is taken of systematic errors -- we use data sets that have almost the same wavelength samplings, use the same code to fit SEDs with the same set of templates, and compare relative differences between the two samples. We find that the PKS1138 galaxies have similar ages, shorter star formation time scales, lower star formation rates, and weaker dust extinction compared to the GOODS galaxies at z~2. This trend is similar to that observed locally, suggesting that the environmental dependence of galaxy properties is already partly in place as early as z=2.15. We ...

  18. Formation of quasiperiodic bimetal thin films with controlled optical and electrical properties

    Science.gov (United States)

    Arakelian, S.; Vartanyan, T.; Istratov, A.; Kutrovskaya, S.; Kucherik, A.; Itina, T.; Osipov, A.

    2016-04-01

    Synthesis of transparent conductive coatings is a promising direction of modern nanotechnological research. Thin nanostructured noble-metallic films demonstrate nonlinear optical effects in visible spectral range because of their plasmonic properties [1]. In addition, optical characteristics of these thin films strongly depend on the period of the formed surface structures [2]. If the distance between deposited particles almost equals their sizes, the optical properties of the randomly deposited structures may considerably differ from these for periodical structures [3]. In this work, we have studied the degree of the morphology influence (particle diameter in the colloid, the distance between the deposited particles, the number of layers etc.) on the optical and electrical properties of the deposited thin film of bimetallic gold and silver clusters. In this work we used CW-laser with moderate intensity in liquid (water or ethanol) for synthesis nanoparticles of noble metals. For the formation of quasi-periodically arranged clusters, particle deposition from the colloidal systems is used. The optical properties of the deposited bimetallic films are shown to change as a function of composition and geometry in agreement with the modeling of the optical properties.

  19. ELECTRICAL AND MECHANICAL PROPERTIES OF POLYANILINE FILMS-EFFECT OF NEUTRAL SALTS ADDED DURING POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The electrical and mechanical properties of polyaniline (PANI) films synthesized by the presence of the selected neutral salts in the polymerization were measured as a function of the properties and the concentration of the selected neutral salts, and the protonation state. It was found that both the electrical and mechanical properties of PANI films were enhanced by adding neutral salts in the polymerization. The adding of the neutral salts in the polymerization resulted in extended conformation of polymer chain and increasing of molecular weight of PANI, which may be the reasons why the electrical and mechanical properties of PANI films were improved by the presence of neutral salts in the polymerization.

  20. On the structural, morphological, optical and electrical properties of sol-gel deposited ZnO:In films

    Energy Technology Data Exchange (ETDEWEB)

    Girtan, M., E-mail: mihaela.girtan@univ-angers.f [L PHI A, FRE CNRS 2988, 2, Bd. Lavoisier, University of Angers (France); Socol, M. [National Institute of Materials Physics, Bucharest (Romania); Pattier, B. [LPEC, UMR CNRS 6087 Universite du Maine, Le Mans (France); Sylla, M. [L PHI A, FRE CNRS 2988, 2, Bd. Lavoisier, University of Angers (France); Stanculescu, A. [National Institute of Materials Physics, Bucharest (Romania)

    2010-11-01

    Indium-doped zinc oxide thin films deposition was performed by the sol-gel technique using homogeneous and stable solutions of zinc acetate 2-hydrate and indium chloride in ethanol. Films were spin coated onto glass substrates. After drying and after a heat treatment at 450 {sup o}C, highly transparent (80%-90%) films were obtained. The effect on the structural, morphological, optical and electrical thin films properties of the dopant concentration was investigated. The temperature dependencies of the electrical conductivity under vacuum and in open atmosphere were analysed and discussed.

  1. Pyroelectric properties and electrical conductivity in samarium doped BiFeO 3 ceramics

    KAUST Repository

    Yao, Yingbang

    2012-06-01

    Samarium (Sm 3+) doped BiFeO 3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopted a rapid heating as well as cooling during the sintering process. The pyroelectric coefficient increased from 93 to 137 μC/m 2 K as the Sm 3+ doping level increased from 1 mol% to 8 mol%. Temperature dependence of the pyroelectric coefficient showed an abrupt decrease above 80 °C in all samples, which was associated with the increase of electrical conductivity with temperature. 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 with increasing Sm 3+ doping level. On the basis of our results, the effects of Sm doping level on the pyroelectric and electrical properties of the BFO were revealed. © 2011 Elsevier Ltd. All rights reserved.

  2. Size and surface effects on the electrical properties of metallic nanowires

    Science.gov (United States)

    Huang, Qiaojian

    The following three topics are discussed in this thesis: (1) Investigation of the electrical properties for copper (Cu), silver (Ag), and gold (Au) nanowires; (2) Development of a theory for size and surface effects on the electrical properties of metallic nanowires; (3) Identifying contamination effects on the electrical measurements of metallic nanowires. For polycrystalline Cu nanowires, electrical resistivity was found to increase when the wire widths decrease as a result of surface and grain boundary scattering effects. In order to isolate the effects of surface scattering from grain boundary scattering, single crystalline trapezoidal Ag nanowires were self-assembled on vicinal silicon substrate. Fuchs-Sondheimer theory was extended to model surface scattering effect on the electrical resistivity of the single crystalline trapezoidal Ag nanowires. The theoretically calculated resistivity was found to increase with decreasing wire cross-sectional area and the measured resistivities were found to be in good agreement. Finally, size and surface effects were also studied for the temperature coefficient of resistance for Cu nanowires. Current-voltage failure measurements for Au and Cu nanowires were found to exhibit higher failure current densities when the wire widths decrease for nanowires with a constant thickness. As a case study, the width dependent failure current density of Cu nanowires was modeled with the finite element method. The increase in failure current density was attributed to the heat transfer between the nanowire contact area and the substrate. In addition, the electromigration experiments were performed for Au and Cu nanowires with a scanning electron microscope to identify nanowire defect formation. The mean-time-to-failure was measured and applied to Black's Law to determine the activation energy for Au and Cu nanowires with sub-100 nm dimensions. Auger electron spectroscopy analysis on Cu electromigration indicates surface migration of Cu, C

  3. Electric-field and temperature dependence of the activation energy associated with gate induced drain leakage

    Science.gov (United States)

    Alnuaimi, Aaesha; Nayfeh, Ammar; Koldyaev, Victor

    2013-01-01

    We examined the effect of temperature and electric field on the activation energy (Ea) of gate-induced drain leakage (GIDL) of a MOSFET. The measured GIDL current shows a temperature dependence consistent with a non-tunneling mechanism. In the low-electric-field regime and for temperatures above 55 °C, Ea is about 0.4 eV and drops from 0.4 eV to 0.1 eV as the applied gate voltage goes below VFB in the accumulation direction (decreased for the n-channel MOSFET). This suggests that electron-hole-pair generation at Si/SiO2 interface traps (Dit), enhanced by the electric field (the Poole-Frenkel effect), dominates GIDL in that regime. For temperatures below 55 °C, Ea is less than 0.15 eV for both weak and strong electric fields and displays minimal temperature dependence, indicating inelastic trap-assisted tunneling or phonon-assisted tunneling from a trap. In the very strong-electric-field regime (>1 MV/cm), band-to-band tunneling is the dominant mechanism.

  4. Delay-Dependent Response in Weakly Electric Fish under Closed-Loop Pulse Stimulation.

    Directory of Open Access Journals (Sweden)

    Caroline Garcia Forlim

    Full Text Available In this paper, we apply a real time activity-dependent protocol to study how freely swimming weakly electric fish produce and process the timing of their own electric signals. Specifically, we address this study in the elephant fish, Gnathonemus petersii, an animal that uses weak discharges to locate obstacles or food while navigating, as well as for electro-communication with conspecifics. To investigate how the inter pulse intervals vary in response to external stimuli, we compare the response to a simple closed-loop stimulation protocol and the signals generated without electrical stimulation. The activity-dependent stimulation protocol explores different stimulus delivery delays relative to the fish's own electric discharges. We show that there is a critical time delay in this closed-loop interaction, as the largest changes in inter pulse intervals occur when the stimulation delay is below 100 ms. We also discuss the implications of these findings in the context of information processing in weakly electric fish.

  5. Investigations of temperature dependences of electrical resistivity and specific heat capacity of metals

    Energy Technology Data Exchange (ETDEWEB)

    Eser, Erhan, E-mail: eserphy@gmail.com [Department of Physics, Polatlı Faculty of Arts and Sciences, Gazi University, Polatlı, Ankara (Turkey); Koç, Hüseyin [Department of Electrical and Electronics Engineering, Faculty of Engineering, Muş Alparslan University, Muş (Turkey)

    2016-07-01

    In this study, we calculated the electrical resistivity and heat capacities of some ideal metals (Cu, Pt, and Pd) using a method that it employs the statistical model and Debye functions. The method is used to provide a simple and reliable analytical procedure for wide temperature range. The results obtained for the electrical resistivity and heat capacity have been compared with the results in literature. The results obtained at low temperature are in excellent agreement with experimental and theoretical results. Finally the used approximation and analytical method are a useful approach to calculate thermophysical properties of metals.

  6. Depth dependent properties of ITO thin films grown by pulsed DC sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Sytchkova, A., E-mail: anna.sytchkova@enea.it [ENEA Optical Coatings Laboratory, via Anguillarese 301, 00123 Rome (Italy); Zola, D. [ENEA Optical Coatings Laboratory, via Anguillarese 301, 00123 Rome (Italy); Bailey, L.R.; Mackenzie, B.; Proudfoot, G. [Oxford Instruments Plasma Technology, Yatton, Bristol, BS49 4AP (United Kingdom); Tian, M. [NT-MDT Europe BV, High Tech Campus 83, 5656 AG Eindhoven (Netherlands); Ulyashin, A. [SINTEF Materials and Chemistry, Forskningsveien 1, P.O. 124 Blindern, NO-0314 Oslo (Norway)

    2013-05-15

    A systematically prepared set of ITO layers for solar cell applications has been analyzed by spectroscopic variable angle ellipsometry in order to trace the dependence of free carriers’ distribution along the film depth as a function of film thickness as well as its change upon annealing. Samples were deposited on silicon substrates with various thicknesses in steps of approximately 10–20 nm. This set was duplicated and these samples were annealed, so that for each thickness an as-deposited and an annealed sample is available. Conventionally measured electrical conductivity and morphological properties (AFM measurements) of the films have been compared with the optical constants’ inhomogeneity, i.e. material properties along the film thickness modelled by variable-angle spectroscopic ellipsometry. The obtained results show that the optical as well as electrical properties of thin ITO films prepared by pulsed DC sputtering are depth dependent. For the deposition conditions used a well-determined reproducible non-uniform distribution of free carriers within the film thickness was determined. In particular it has been found that the majority of free carriers in as-deposited ultra-thin ITO films is concentrated at sample half-depth, while their distribution becomes asymmetric for the thicker films, with a maximum located at approximately 40 nm depth. The distribution of free carriers in annealed samples is qualitatively different from that of as-deposited layers.

  7. Ferro electrical properties of GeSbTe thin films; Propiedades ferroelectricas de peliculas delgadas de GeSbTe

    Energy Technology Data Exchange (ETDEWEB)

    Gervacio A, J. J.; Prokhorov, E.; Espinoza B, F. J., E-mail: jgervacio@qro.cinvestav.m [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico)

    2011-07-01

    The aim of this work is to investigate and compare ferro electrical properties of thin GeSbTe films with composition Ge{sub 4}Sb{sub 1}Te{sub 5} (with well defined ferro electrical properties) and Ge{sub 2}Sb{sub 2}Te{sub 5} using impedance, optical reflection, XRD, DSc and Piezo response Force Microscopy techniques. The temperature dependence of the capacitance in both materials shows an abrupt change at the temperature corresponding to ferroelectric-paraelectric transition and the Curie-Weiss dependence. In Ge{sub 2}Sb{sub 2}Te{sub 5} films this transition corresponds to the end from a NaCl-type to a hexagonal transformation. Piezo response Force Microscopy measurements found ferroelectric domains with dimension approximately equal to the dimension of grains. (Author)

  8. Size effects in electrical and magnetic properties of quasi-one-dimensional tin wires in asbestos

    Science.gov (United States)

    Chernyaev, A. V.; Shamshur, D. V.; Fokin, A. V.; Kalmykov, A. E.; Kumzerov, Yu. A.; Sorokin, L. M.; Parfen'ev, R. V.; Lashkul, A.

    2016-03-01

    Bulk composites have been prepared based on one-dimensional fibers of natural chrisothil-asbestos with various internal diameters ( d = 6-2.5 nm) filled with tin. The electrical and magnetic properties of quasi-one-dimensional Sn wires have been studied at low temperatures. The electrical properties have been measured at T = 300 K at a pressure P = 10 kbar. It has been found that the superconducting (SC) characteristics of the nanocomposites (critical temperature T c and critical magnetic field H c) increase as the Sn filament diameter decreases. The temperature spreading of the resistive SC transition also increases as the Sn filament diameter decreases, which is explained by the SC order parameter fluctuations. The size effects (the increase in critical temperature T c and transition width Δ T c) in Sn nanofilaments are well described by the independent Aslamazov-Larkin and Langer-Ambegaokara fluctuation theories, which makes it possible to find the dependence of T c of the diffuse SC transition on the nanowire diameter. Using the temperature and magnetic-field dependences of the magnetic moment M( T, H), it has been found that the superconductor-normal metal phase diagram of the Sn-asbestos nanocomposite has a wider region of the SC state in T and H as compared to the data for bulk Sn. The magnetic properties of chrisotil-asbestos fibers unfilled with Sn have been studied. It has been found that the Curie law is fulfilled and that the superparamagnetism is absent in such samples. The obtained results indicate the absence of magnetically ordered impurities (magnetite) in the chrisotil-asbestos matrix, which allowed one to not consider the problem of the interaction of the magnetic subsystem of the asbestos matrix and the superconducting subsystem of Sn nanowires.

  9. GPR-based evaluation of strength properties of unbound pavement material from electrical characteristics

    Science.gov (United States)

    Benedetto, Andrea; D'Amico, Fabrizio; Tosti, Fabio

    2013-04-01

    It is well known that inter-particle friction and cohesion of soil particles and aggregates deeply affect the strength and deformation properties of soils, exerting critical effects on the bearing capacity of unbound pavement materials. In that respect, considering that strength characteristics of soil are highly dependent on particle interactions, and assuming a relationship between electric properties (e.g. electric permittivity) and bulk density of materials, a good correlation between mechanical and electric characteristics of soil is expected. In this work, Ground Penetrating Radar (GPR) techniques are used to investigate this topic. Two GPR equipment with same electronic characteristics and different survey configurations are used. Each radar operates with two ground-coupled antennae at 600 MHz and 1600 MHz central frequencies. Measurements are developed using 4 channels, 2 mono-static and 2 bi-static. The received signal is sampled in the time domain at dt = 7.8125 × 10-2 ns, and in the space domain every 2.4 × 10-2 m. A semi-empirical model is proposed for predicting the resilient modulus of sub-asphalt layers from GPR-derived data. Basically, the method requires to follow two steps. Firstly, laboratory tests are carried out for calibration, with the main focus to provide consistent empirical relationships between physical (e.g. bulk density) and electric properties. The second step is focused on the in-situ validation of results through soil strength measurements retrieved by CBR tests and Light Falling Weight Deflectometer (LFWD). On the basis of traditional empirical equations used for flexible pavement design, the following expression is proposed: -m Ei = αj?hj,i j=1 where Ei [MPa] is the ith expected resilient modulus of the surveyed soil under the line of scan, hj,i [m] is the ith thickness referred to the jth layer, and αj is a dielectric parameter calibrated as a function of the relative electric permittivity. The experimental setting requires

  10. Alternating current electrical properties of Argon plasma treated jute

    Directory of Open Access Journals (Sweden)

    Md. Masroor Anwer

    2012-09-01

    Full Text Available Low temperature plasma (LTP treatment, a kind of environment friendly surface modification technique, was applied to biodegradable and environment friendly jute fibre with the use of nonpolymerizing gas, namely argon, at various discharge power levels and exposure times with a definite flow rate. Scanning electron microscopy (SEM microphotographs reveal that the roughness of the fibre surfaces increases with the increase of discharge power and exposure time. This is caused due to the bombardment of high energetic ions on the fibre surface and the fibres become sputtered. The capacitance and the electrical conductance of raw and LTP treated jute fibre were measured as a function of frequency at room temperature. The dielectric constant, conductivity, dielectric loss-tangent and the surface morphology of raw and LTP treated jute as a function of frequency were studied at room temperature. It was observed that for all the samples the dielectric constant almost constant at lower frequencies and then decreases gradually in the high frequency region. In addition, dielectric constant increases with the increase of plasma treatment time as well as discharge power. It is also observed for all the samples that the conductivity increases as the frequency increases with a lower slope in the low frequency region and with a higher slope in the higher frequency region. In addition, the conductivity decreases with the increase of plasma exposure time as well as discharge power. The conductivity increases with frequency due to the hopping mechanism of electrons. The dependence of the dielectric loss-tangent with frequency at different treatment times and discharge powers for all the jute samples show small relaxation peaks in the very low frequency region. The dielectric loss-tangent decreases with the increase of both plasma treatment time and discharge power. In addition, the relaxation peaks are shifted to the higher frequency region as the plasma treatment

  11. Electrical transport properties of metal and graphene contacts to MoS2

    Science.gov (United States)

    Luo, Yunqiu (Kelly); Wen, Hua; Zhu, Tiancong

    2014-03-01

    Two-dimensional crystals are an exciting class of materials for novel physics and nanoelectronics. MoS2 and related transition metal dichalcogenides have received tremendous interest due to its native band gap and strong spin orbit coupling. Unlike graphene, the presence of the band gap leads to transistors with high on-off ratios. One important issue is the electrical properties of the contacts to the MoS2. Recent studies have shown the presence of a Schottky barrier and its dependence on the metal workfunction, back gate voltage, and interfacial oxide barriers. In this work, we investigate the interfacial properties of metal to MoS2 contact and graphene to MoS2 contact by studying the junction's Schottky barrier formation and bias dependence. We utilize a polymer based transfer method to precisely position exfoliated graphene flakes onto exfoliated MoS2 flakes. We intensively study various junction combination between monolayer/few-layer graphene and monolayer/few-layer MoS2. Dependence on temperature and back gate will be discussed.

  12. Temperature Dependence of Photoelectrical Properties of Single Selenium Nanowires

    Directory of Open Access Journals (Sweden)

    Liu Li-Ping

    2010-01-01

    Full Text Available Abstract Influence of temperature on photoconductivity of single Se nanowires has been studied. Time response of photocurrent at both room temperature and low temperature suggests that the trap states play an important role in the photoelectrical process. Further investigations about light intensity dependence on photocurrent at different temperatures reveal that the trap states significantly affect the carrier generation and recombination. This work may be valuable for improving the device optoelectronic performances by understanding the photoelectrical properties.

  13. Depth-Dependent Temporal Response Properties in Core Auditory Cortex

    OpenAIRE

    Christianson, G. Björn; Sahani, Maneesh; Linden, Jennifer F.

    2011-01-01

    The computational role of cortical layers within auditory cortex has proven difficult to establish. One hypothesis is that interlaminar cortical processing might be dedicated to analyzing temporal properties of sounds; if so, then there should be systematic depth-dependent changes in cortical sensitivity to the temporal context in which a stimulus occurs. We recorded neural responses simultaneously across cortical depth in primary auditory cortex and anterior auditory field of CBA/Ca mice, an...

  14. On the Dependence of the Ionospheric E-Region Electric Field of the Solar Activity

    Science.gov (United States)

    Denardini, Clezio Marcos; Schuch, Nelson Jorge; Moro, Juliano; Araujo Resende, Laysa Cristina; Chen, Sony Su; Costa, D. Joaquim

    2016-07-01

    We have being studying the zonal and vertical E region electric field components inferred from the Doppler shifts of type 2 echoes (gradient drift irregularities) detected with the 50 MHz backscatter coherent (RESCO) radar set at Sao Luis, Brazil (SLZ, 2.3° S, 44.2° W) during the solar cycle 24. In this report we present the dependence of the vertical and zonal components of this electric field with the solar activity, based on the solar flux F10.7. For this study we consider the geomagnetically quiet days only (Kp <= 3+). A magnetic field-aligned-integrated conductivity model was developed for proving the conductivities, using the IRI-2007, the MISIS-2000 and the IGRF-11 models as input parameters for ionosphere, neutral atmosphere and Earth magnetic field, respectively. The ion-neutron collision frequencies of all the species are combined through the momentum transfer collision frequency equation. The mean zonal component of the electric field, which normally ranged from 0.19 to 0.35 mV/m between the 8 and 18 h (LT) in the Brazilian sector, show a small dependency with the solar activity. Whereas, the mean vertical component of the electric field, which normally ranges from 4.65 to 10.12 mV/m, highlight the more pronounced dependency of the solar flux.

  15. Azimuthal dependence of the Garton-Tomkins orbit in crossed magnetic and electric fields

    Science.gov (United States)

    Bleasdale, C.; Lewis, R. A.; Bruno-Alfonso, A.

    2016-08-01

    Work on classical closed orbits in the diamagnetic Kepler problem is predominately focused on the chaos observed in the polar launch angle as opposed to the azimuthal launch angle. This is due to atomic systems, along with widely studied external-field geometries (parallel magnetic and electric fields or pure magnetic field), being uniform in azimuthal angle, rendering the azimuthal angle unimportant. In the case of crossed magnetic and electric fields, this is no longer the case, and closed orbits do present an azimuthal launch angle dependence. In atomic systems, due to their spherical symmetry, the electric-field orientation in the plane perpendicular to the magnetic field does not affect the spectrum of orbits. However, in shallow n -type donors in anisotropic semiconductors such as silicon, the orientation of the external fields with respect to conduction-band valleys will be important. In this work we examine the Garton-Tomkins orbit in crossed magnetic and electric fields, and analyze how it and its harmonics' azimuthal dependencies behave through variation of the scaled field or scaled energy. At low scaled fields, harmonics have either twofold or fourfold azimuthal dependencies determined by the rotational symmetry of the individual harmonics. As the scaled field or scaled energy is increased, several harmonics undergo significant bifurcations, resulting in large azimuthal angular regions of essentially closed orbits, which will lead to strong resonances in experimental work.

  16. Preparation of MWNTs/Al2O3 composites and their mechanical and electrical properties

    Institute of Scientific and Technical Information of China (English)

    FAN; Jinpeng; ZHAO; Daqing; XU; Zening; WU; Minsheng

    2005-01-01

    The mechanical and electrical properties of MWNTs/Al2O3 composite prepared fabricated by hot pressing are investigated. The relation between properties and microstructure of composites is also discussed. With 4wt% MWNTs as reinforcement, the fracture toughness of composite obtained reaches 5.55 Mpa·m1/2, which is 80% higher than that of pure Al2O3 obtained in the same conditions. The main toughening mechanism is CNTs' pinning alumina grain boundaries, and the pullout of CNTs takes effect also. Through adding 2wt% MWNTs and altering the mix method, the fracture toughness of the composite obtained is 3.97 Mpa·m1/2. Furthermore, the electrical resistivity is as low as 8.4×10-3Ω·m, decreasing by 14 orders of magnitude compared with pure alumina ceramics. The function of CNTs in composite is related to the distribution state of CNTs in composite, and the distribution state of CNTs in matrix is dependent on preparation procedures.

  17. Mechanical and electrical properties of low temperature phase MnBi

    Science.gov (United States)

    Jiang, Xiujuan; Roosendaal, Timothy; Lu, Xiaochuan; Palasyuk, Olena; Dennis, Kevin W.; Dahl, Michael; Choi, Jung-Pyung; Polikarpov, Evgueni; Marinescu, Melania; Cui, Jun

    2016-01-01

    Low temperature phase (LTP) manganese bismuth (MnBi) is a promising rare-earth-free permanent magnet material due to its high intrinsic coercivity and large positive temperature coefficient. While scientists are making progress on fabricating bulk MnBi magnets, engineers have begun considering MnBi magnets for motor applications. Physical properties other than magnetic ones could significantly affect motor design. Here, we report results of our investigation on the mechanical and electrical properties of bulk LTP MnBi and their temperature dependence. A MnBi ingot was prepared using an arc melting technique and subsequently underwent grinding, sieving, heat treatment, and cryomilling. The resultant powders with a particle size of ˜5 μm were magnetically aligned, cold pressed, and sintered at a predefined temperature. Micro-hardness testing was performed on a part of original ingot and we found that the hardness of MnBi was 109 ± 15 HV. The sintered magnets were subjected to compressive testing at different temperatures and it was observed that a sintered MnBi magnet fractured when the compressive stress exceeded 193 MPa at room temperature. Impedance spectra were obtained using electrochemical impedance spectroscopy at various temperatures and we found that the electrical resistance of MnBi at room temperature was about 6.85 μΩ m.

  18. Electrical Transport Properties of Mn doped Bi2Se3 Thin Films

    Science.gov (United States)

    Babakiray, Sercan; Johnson, Trent; Borisov, Pavel; Lederman, David

    2015-03-01

    Magnetic impurity doping in topological insulators manifest itself with a gap opening in the Dirac cone as a result of breaking the time reversal symmetry. Moreover, the magnetic impurities affect the structural and quantum transport properties of topological insulators by increasing the disorder and by changing the bulk charge carrier type, charge carrier density and Hall mobility. Here, we investigated the effect of Mn doping on the structural and electrical transport properties of Bi2-xMnxSe3 thin films which are 12 quintuple layers thick and grown on Al2O3 (0001) single crystal substrates via molecular beam epitaxy (MBE). Hikami-Larkin-Nagaoka (HLN) formalism was used to study the weak antilocalization (WAL). Increasing Mn doping concentration was found to increase the bulk charge carrier density and to decrease the Hall mobility. A decrease was also observed in the phase coherence length related to WAL as a function of Mn content x. Values of another WAL parameter, the pre-factor alpha, showed that the top and bottom surfaces were coupled through the bulk conducting channels. The temperature dependence of phase coherence length indicated the electrical transport was dominated by 2D electron-electron scattering for the undoped, and by bulk weak localization effects for the Mn doped samples, respectively.

  19. Structural mosaicity and electrical properties of pyrolytic SnO{sub 2}:F thin films

    Energy Technology Data Exchange (ETDEWEB)

    Garcés, F.A., E-mail: fgarces@intec.unl.edu.ar [Instituto de Desarrollo Tecnológico para la Industria Química, UNL-CONICET, Güemes 3450, S3000GLN Santa Fe (Argentina); Budini, N. [Instituto de Desarrollo Tecnológico para la Industria Química, UNL-CONICET, Güemes 3450, S3000GLN Santa Fe (Argentina); Koropecki, R.R.; Arce, R.D. [Instituto de Desarrollo Tecnológico para la Industria Química, UNL-CONICET, Güemes 3450, S3000GLN Santa Fe (Argentina); Facultad de Ingeniería Química, UNL, Santiago del Estero 2829, S3000AOM Santa Fe (Argentina)

    2013-03-01

    In this work we present structural and electrical properties of SnO{sub 2}:F thin films deposited on glass substrate by the spray pyrolysis technique. The precursors of SnO{sub 2}:F were synthesized by a sol–gel method, starting from a SnCl{sub 4}·5H{sub 2}O/ethanol mixture and using NH{sub 4}F/H{sub 2}O as a dopant. Different properties were observed depending on the deposition time of the films. The structural characteristics of the layers, like crystal size, preferential growth orientation and mosaicity, were studied by X-ray diffraction. These results were compared and correlated with those obtained from electrical measurements, such as carrier density, Hall mobility and resistivity. We have found that for longer deposition times, the mosaicity of the crystallites increases. This process is accompanied by a decrease in the resistivity. - Highlights: ► Tin oxide doped on glass substrate as thin film ► Mosaicity studies enable information about of crystalline domains. ► Increasing time deposition allows modification of resistivity and Hall mobility. ► Increasing the film thickness occur changes in crystalline texture.

  20. Characteristics of electricity generation with intermittent sources depending on the time resolution of the input data

    Science.gov (United States)

    Wagner, F.; Wertz, F.

    2016-08-01

    Data on the electricity supply with intermittent renewable sources are made public by the Transmission System Operators (TSO) and other sources. Data are typically provided in 1h increments. In this paper, we analyse wind and photo-voltaic data from the Czech Republic. The analysis concentrates on major characteristics of a supply situation where the annual demand is formally met by scaled-up wind and photovoltaic power. The original data are supplied in 1min increments and successively averaged up to 1h time resolution. This paper focuses on the dependence of the major supply characteristics on the time resolution of the available electricity data.

  1. Magnetic field dependence of the threshold electric field in unconventional charge density waves

    Science.gov (United States)

    Dóra, Balázs; Virosztek, Attila; Maki, Kazumi

    2002-04-01

    Many experiments suggest that the unidentified low-temperature phase of α-(BEDT-TTF)2KHg(SCN)4 is most likely unconventional charge density wave (UCDW). To further extend this identification we present our theoretical study of the threshold electric field of UCDW in a magnetic field. The magnetic field-temperature phase diagram is very similar to those in a d-wave superconductor. The optical conductivity shows clear features characteristic to both UDW and magnetic field. We find a rather strong field dependence of the threshold electric field, which shows qualitatively good agreement with the experimental data.

  2. Temperature dependent electrical resistivity of gallium and antimony in a liquid form

    Science.gov (United States)

    Prajapati, A. V.; Sonvane, Y. A.; Thakor, P. B.

    2016-05-01

    Present paper deals with the effects of temperature variation on the electrical resistivity (Ω) of liquid Gallium (Ga), and Antimony (Sb). We have used a new parameter free pseudopotential with a Zeeman formula for finding it. To see the effects of screening Farid et al local field correction function is used with the Charged Hard Sphere (CHS) reference system. Analysis and comparison between the plotted graphs, based on present computed data and other experimental data defines and conclude that our newly constructed model potential is an effective one to produce the data for the temperature dependent electrical resistivity of some liquid semiconductors.

  3. Conductive magnetorheological elastomer: fatigue dependent impedance-mechanic coupling properties

    Science.gov (United States)

    Wang, Yu; Xuan, Shouhu; Ge, Lin; Wen, Qianqian; Gong, Xinglong

    2017-01-01

    This work investigated the relationship between the impedance properties and dynamic mechanical properties of magnetorheological elastomers (MREs) under fatigue loading. The storage modulus and the impedance properties of MREs were highly influenced by the pressure and magnetic field. Under the same experimental condition, the two characteristics exhibited similar fatigue dependent change trends. When pressure was smaller than 10 N, the capacitance of MRE could be divided into four sections with the increase of the cyclic numbers. The relative equivalent circuit model was established to fit the experimental results of the impedance spectra. Each parameter of circuit element reflected the change of fatigue loading, relative microstructure of MRE, MRE-electrode interface layer, respectively. Based on the above analysis, the real-time and nondestructive impedance method was demonstrated to be high potential on detecting the fatigue of the MRE device.

  4. Concentration dependences of the physicochemical properties of a water-acetone system

    Science.gov (United States)

    Fedyaeva, O. A.; Poshelyuzhnaya, E. G.

    2017-01-01

    Concentration dependences of the UV spectrum, refractive index, specific electrical conductivity, boiling point, pH, surface tension, and heats of dissolution of a water-acetone system on the amount of acetone in the water are studied. It is found that the reversible protolytic interaction of the components occurs in all such solutions, resulting in the formation of hydroxyl and acetonium ions. It is shown that shifts of the equilibrium between the molecules and ions in the solution leads to extreme changes in their electrical properties. It is concluded that the formation of acetone solutions of water is accompanied by heat absorption, while the formation of aqueous solutions of acetone is accompanied by heat release.

  5. Effect of primycin on some electric properties of the frog skeletal muscle.

    Science.gov (United States)

    Gesztelyi, I; Kónya, L; Kövér, A

    1980-01-01

    The effect of primycin, a guanidine-type antibiotic was studied on the electric properties and 42K+ uptake of the frog sartorius and semitendinosus muscle. Both in normal and choline chloride Ringer solution, primycin evoked a concentration and time dependent depolarization of the surface membrane of the muscle. This depolarization was significantly increased by Na ions. Primycin treatment was shown to evoke a dose-dependent decrease of the depolarization induced by 20 mM K+-Ringer. When the muscles were incubated in a Ringer solution containing choline chloride, during an incubation period of 30 min the uptake of 42K+ was decreased to 12% upon the exposure to 5 x 10(-6) mol primycin as compared to the control value. As the primycin-induced depolarization increased, the shape and amplitude of the action potentials elicited by square-wave electric impulses were altered and decreased, respectively. In sodium isaethionate Ringer 1--2 x 10(-6) M primycin induced a slow depolarization resulting in firing potentials. The results suggest that primycin depolarizes the surface membrane exclusively through the blockade of the resting K+ channels, the other phenomena being the results of this depolarizing effect.

  6. Influence of Zn doping on electrical and optical properties of multilayered tin oxide thin films

    Indian Academy of Sciences (India)

    J S Bhat; K I Maddani; A M Karguppikar

    2006-06-01

    In this study, the electrical and optical properties of Zn doped tin oxide films prepared using sol–gel spin coating process have been investigated. The SnO2 : Zn multi-coating films were deposited at optimum deposition conditions using a hydroalcoholic solution consisting of stannous chloride and zinc chloride. Films with Zn doping levels from 0–10 wt% in solution are developed. The results of electrical measurements indicate that the sheet resistance of the deposited films increases with increasing Zn doping concentration and several superimposed coatings are necessary to reach expected low sheet resistance. Films with three coatings show minimum sheet resistance of 1.479 k/ in the case of undoped SnO2 and 77 k/ for 5 wt% Zn doped SnO2 when coated on glass substrate. In the case of single layer SnO2 film, absorption edge is 3.57 eV and when doped with Zn absorption edge shifts towards lower energies (longer wavelengths). The absorption edge lies in the range of 3.489–3.557 eV depending upon the Zn doping concentration. The direct and indirect transitions and their dependence on dopant concentration and number of coatings are presented.

  7. Enhanced electrical properties in Nd doped cobalt ferrite nano-particles

    Science.gov (United States)

    Abbas, S.; Munir, A.; Zahra, F.; Rehman, M. A.

    2016-08-01

    Spinel ferrites are important class of compounds which has variety of electrical, magnetic and catalytic applications. A small amount of rare earth element causes modification in structural, electrical and magnetic properties of ferrite materials for practical applications. Neodymium doped cobalt ferrites with composition CoNdxFe2-xO4 where x is 0.1 has been synthesized by sol-gel method. Sol-gel method was preferred because it has good control over stoichiometry, crystallite size and particle size distribution. Characterization was done by using X-Ray Diffraction (XRD) technique for structural analysis and crystal structure was found to be spinel. Particles like morphology was observed in micrographs obtained by Scanning Electron Microscopy (SEM). Thermal analysis of sample has been done which includes Thermogravimetric analysis (TGA) and Differential Scanning calorimetry (DSC). Fourier transform infra-red spectroscopy (FT-IR) of samples was also performed. DC resistivity as a function of temperature has been studied and its shows direct dependence on temperature and inverse dependence on the concentration of Nd dopant. The studied material is a potential candidate for resistive random access memory application.

  8. Enhancement of antibacterial properties of Ag nanorods by electric field

    Directory of Open Access Journals (Sweden)

    Omid Akhavan and Elham Ghaderi

    2009-01-01

    Full Text Available The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20–60 nm and a length of 260–550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100 thin film during its heat treatment at 700 °C in an Ar+H2 environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {100} facets. The antibacterial activity of the silver nanorods against Escherichia coli bacteria was evaluated at various electric fields applied in the direction of the nanorods without any electrical connection between the nanorods and the capacitor plates producing the electric field. Increasing the electric field from 0 to 50 V cm−1 resulted in an exponential increase in the relative rate of reduction of the bacteria from 3.9×10−2 to 10.5×10−2 min−1. This indicates that the antibacterial activity of silver nanorods can be enhanced by applying an electric field, for application in medical and food-preserving fields.

  9. Enhancement of antibacterial properties of Ag nanorods by electric field

    Energy Technology Data Exchange (ETDEWEB)

    Akhavan, Omid [Department of Physics, Sharif University of Technology, PO Box 11155-9161, Tehran (Iran, Islamic Republic of); Ghaderi, Elham [Tehran University of Medical Sciences, PO Box 14155-6447, Tehran (Iran, Islamic Republic of)], E-mail: oakhavan@sharif.edu

    2009-01-15

    The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20-60 nm and a length of 260-550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100) thin film during its heat treatment at 700 deg. C in an Ar+H{sub 2} environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {l_brace}100{r_brace} facets. The antibacterial activity of the silver nanorods against Escherichia coli bacteria was evaluated at various electric fields applied in the direction of the nanorods without any electrical connection between the nanorods and the capacitor plates producing the electric field. Increasing the electric field from 0 to 50 V cm{sup -1} resulted in an exponential increase in the relative rate of reduction of the bacteria from 3.9x10{sup -2} to 10.5x10{sup -2} min{sup -1}. This indicates that the antibacterial activity of silver nanorods can be enhanced by applying an electric field, for application in medical and food-preserving fields.

  10. Spin polarization dependence of quasiparticle properties in graphene

    Science.gov (United States)

    Qaiumzadeh, A.; Jahanbani, Kh.; Asgari, Reza

    2012-06-01

    We address spin polarization dependence of graphene's Fermi liquid properties quantitatively using a microscopic random phase approximation theory in an interacting spin-polarized Dirac electron system. We show an enhancement of the minority-spin many-body velocity renormalization at fully spin polarization due to reduction in the electron density and consequently increase in the interaction between electrons near the Fermi surface. We also show that the spin dependence of the Fermi velocity in the chiral Fermi systems is different than that in a conventional two-dimensional electron liquid. In addition, we show that the ratio of the majority-to-minority-spin lifetime is smaller than unity and related directly to the polarization and electron energy. The spin-polarization dependence of the carrier Fermi velocity is of significance in various spintronic applications.

  11. Effect of aging in an electric field on microstructures and properties of 1420 Al- Li alloy

    Institute of Scientific and Technical Information of China (English)

    刘北兴; 李洪涛; 覃耀春; 冯海波

    2002-01-01

    After solution treatment, the 1420 Al- Li alloy samples were aged at different temperatures in an e-lectric field with different intensity. The measurements made showed that the electric field increased the strengthofthe 1420 Al -Li alloy, and best properties were obtained when they were aged at 120 ℃ with E = 4 kV/cmfor 12 hrs. The electric field promoted the nucleation ofδ' phase, increased the quantity of the δ' phase, andmade the size of the δ' phase particles smaller. The electric field restrained the formation and growth of PFZ,and increased the intensity of the electric field while the width of the PFZ was decreased.

  12. Physicochemical Properties of Biopolymer Hydrogels Treated by Direct Electric Current

    Directory of Open Access Journals (Sweden)

    Żaneta Król

    2016-07-01

    Full Text Available The objective of this study was to evaluate the changes within the physicochemical properties of gelatine (2%; 4%; 8%, carrageenan (1.5%; 2%; 2.5% and sodium alginate (0.75%; 1%; 1.25% hydrogels with different sodium chloride concentrations that were triggered by applying direct current (DC of 400 mA for a duration of five minutes. There were three types of gels prepared for the purpose of the study: C, control; H, gels on the basis of hydrosols that were treated with DC; and G, gels treated with DC. In the course of the study, the authors carried out the following analyses: Texture Profile Analysis (TPA, Fourier Transform Infrared spectroscopy (FTIR, Scanning Electron Microscopy (SEM and Swelling Ratio (SR. Furthermore, the color and pH of hydrogels were measured. The FTIR spectra showed that the structures of gelatine, carrageenan and sodium alginate do not significantly change upon applying DC. The results of TPA, SR, color and pH measurement indicate that hydrogels’ properties are significantly dependent on the type of polymer, its concentration and the type of the gel. By changing those parameters, the characteristics of such gels can be additionally tuned, which extends their applicability, e.g., in the food industry. Moreover, the analysis revealed that SR of H gel gelatine after 72 h of storage was 1.84-times higher than SR of the control sample, which indicated that this gel may be considered as a possible component for wound dressing materials.

  13. Impact of electric-field dependent dielectric constants on two-dimensional electron gases in complex oxides

    Energy Technology Data Exchange (ETDEWEB)

    Peelaers, H.; Gordon, L.; Steiauf, D.; Janotti, A.; Van de Walle, C. G. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Krishnaswamy, K. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106-9560 (United States); Sarwe, A. [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States); Applied Physics Department, Chalmers Institute of Technology, Gothenburg SE 412-96 (Sweden)

    2015-11-02

    High-density two-dimensional electron gas (2DEG) can be formed at complex oxide interfaces such as SrTiO{sub 3}/GdTiO{sub 3} and SrTiO{sub 3}/LaAlO{sub 3}. The electric field in the vicinity of the interface depends on the dielectric properties of the material as well as on the electron distribution. However, it is known that electric fields can strongly modify the dielectric constant of SrTiO{sub 3} as well as other complex oxides. Solving the electrostatic problem thus requires a self-consistent approach in which the dielectric constant varies according to the local magnitude of the field. We have implemented the field dependence of the dielectric constant in a Schrödinger-Poisson solver in order to study its effect on the electron distribution in a 2DEG. Using the SrTiO{sub 3}/GdTiO{sub 3} interface as an example, we demonstrate that including the field dependence results in the 2DEG being confined closer to the interface compared to assuming a single field-independent value for the dielectric constant. Our conclusions also apply to SrTiO{sub 3}/LaAlO{sub 3} as well as other similar interfaces.

  14. Thickness Dependent Properties of Relaxor-PbTiO(3) Ferroelectrics for Ultrasonic Transducers.

    Science.gov (United States)

    Lee, Hyeong Jae; Zhang, Shujun; Luo, Jun; Li, Fei; Shrout, Thomas R

    2010-09-23

    The electrical properties of Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT) based polycrystalline ceramics and single crystals were investigated as a function of scale ranging from 500 microns to 30 microns. Fine-grained PMN-PT ceramics exhibited comparable dielectric and piezoelectric properties to their coarse-grained counterpart in the low frequency range (40 MHz). For PMN-PT single crystals, however, the dielectric and electromechanical properties degraded with decreasing thickness, while ternary Pb(In(1/2)Nb(1/2))O(3)-Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PIN-PMN-PT) exhibited minimal size dependent behavior. The origin of property degradation of PMN-PT crystals was further studied by investigating the dielectric permittivity at high temperatures, and domain observations using optical polarized light microscopy. The results demonstrated that the thickness dependent properties of relaxor-PT ferroelectrics are closely related to the domain size with respect to the associated macroscopic scale of the samples.

  15. Research Update: Inhomogeneous aluminium dopant distribution in magnetron sputtered ZnO:Al thin films and its influence on their electrical properties

    Directory of Open Access Journals (Sweden)

    André Bikowski

    2015-06-01

    Full Text Available The spatial distribution of Al in magnetron sputtered ZnO:Al films has been investigated in depth. Two different kinds of inhomogeneities were observed: an enrichment in the bulk of the film and an enrichment at the interface to the substrate. This has been correlated to the electrical properties of the films: the former inhomogeneities can lead to trap states at the grain boundaries limiting the free carrier mobility. The latter can promote the formation of secondary phases, which leads to an electrical inactivation of the dopant. Furthermore, this effect can contribute to the thickness dependence of the electrical properties of ZnO:Al films.

  16. Frame Dependence of the Electric Field Spectrum of Solar Wind Turbulence

    CERN Document Server

    Chen, C H K; Salem, C; Mozer, F S

    2011-01-01

    We present the first survey of electric field data using the ARTEMIS spacecraft in the solar wind to study inertial range turbulence. We find that the average perpendicular spectral index of the electric field depends on the frame of measurement. In the spacecraft frame it is -5/3, which matches the magnetic field due to the large solar wind speed in Lorentz transformation. In the mean solar wind frame, the electric field is primarily due to the perpendicular velocity fluctuations and has a spectral index slightly shallower than -3/2, which is close to the scaling of the velocity. These results are an independent confirmation of the difference in scaling between the velocity and magnetic field, which is not currently well understood. The spectral index of the compressive fluctuations was also measured and found to be close to -5/3, indicating that they are not only passive to the velocity but may also interact nonlinearly with the magnetic field.

  17. Sintering and grain size influence on the electrical properties of the Bi{sub 26}Mo{sub 9}WO{sub 69} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, F.C.; Muccillo, R. [Comissao Nacional de Energia Nuclear, Sao Paulo, SP (Brazil). Inst. de Pesquisas Energeticas e Nucleares; Steil, M.C.; Vannier, R.N. [Lab. de Cristallochimie et Physicochimie du Solide, ENSCL, Villeneuve d' Ascq (France)

    2002-07-01

    In the field of oxide ion conduction, bismuth-based materials exhibit interesting electrical properties at moderate temperatures: 300 C - 600 C. The Bi{sub 26}Mo{sub 10-x}W{sub x}O{sub 69} solid solution is a one-dimensional ion conductor with a structure based on [Bi{sub 12}O{sub 14}]{sub {infinity}} columns. The sintering behaviour of the Bi{sub 26}Mo{sub 9}WO{sub 69} powder was studied by dilametric analysis. In order to investigate the influence of the microstructure on the electrical properties of the Bi{sub 26}Mo{sub 9}WO{sub 69} ceramics, dense samples with different grain sizes were produced by isostatic pressing and controlling sintering temperature and time. The electrical properties were studied by impedance spectroscopy. Impedance spectroscopy results show that the electrical conductivity depends on the microstructural properties, remarkably on the grain size. (orig.)

  18. On the Electrical and Magnetic Properties of some Indian Spices

    CERN Document Server

    Baby, Samson K

    2010-01-01

    We have made experimental measurements of electrical conductivity, pH and relative magnetic susceptibility of the aqueous solutions of 24 indian spices. The measured values of electrical conductance of these spices are found to be linearly related to their ash content and bulk calorific values reported in literature. The physiological relevance of the pH and diamagnetic susceptibility of spices when consumed as food or medicine will be also discussed.

  19. Relationships between electrical properties and petrography of El-Maghara sandstone formations, Egypt

    Directory of Open Access Journals (Sweden)

    Mohamed A. Kassab

    2017-06-01

    Full Text Available Realization of electrical and petrography of rocks is absolutely necessary for geophysical investigations. The petrographical, petrophysical and electrical properties of sandstone rocks (El-Maghara Formation, North Sinai, Egypt will be discussed in the present work. The goal of this paper was to highlight interrelations between electrical properties in terms of frequency (conductivity, permittivity and impedance and petrography, as well as mineral composition. Electrical properties including (conductivity and dielectric constant were measured at room temperature and humidity of (∼35%. The frequency range used will be from 10 Hz to 100 kHz. Slight changes between samples in electrical properties were found to result from changes in composition and texture. Electrical properties generally change with grain size, shape, sorting, mineralogy and mineral composition. The dielectric constant decreases with frequency and increases with increasing clay content. The conductivity increases with the increase in conductor channels among electrodes. Many parameters can combine together to lead to the same electrical properties. The samples are mainly composed of sand with clay and carbonate.

  20. Effect of Rare Earth Element Ce on Microstructure and Properties of Aluminum Rod for Electrical Purpose

    Institute of Scientific and Technical Information of China (English)

    Li Pengfei; Wang Yunli; Gao Xizhu; Wang Zaiyun

    2004-01-01

    The effect of rare earth element Ce on microstructure, electrical conductivity and mechanical properties was studied.Using optical microscope, scanning electron microscope, transmission electron microscope and X-ray diffractometer, the microstructure and phase composition of aluminum rod for electrical purpose were measured and analyzed.The results indicate that rare earth element Ce can considerably refine grain size of aluminum rod for electrical purpose,improve the regular distribution pattern of the impurity, such as silicon and iron which present in the aluminum matrix,form stable metal compound with pernicious impurity.This metal compound precipitates on the crystal boundary.As a result, the solid solubility of impurity in aluminum reduce, and the electrical conductivity of aluminum rod for electrical purpose is improved.It is found that the mechanical properties of aluminum rod for electrical purpose are improved by rare earth element in certain range of RE addition.

  1. Electrical properties of magnetron sputtered ZnO:Al samples determined by Hall and Seebeck measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dewald, Wilma; Sittinger, Volker; Szyszka, Bernd [Fraunhofer Institute for Surface Engineering and Thin Films (IST), Braunschweig (Germany); Wimmer, Mark; Ruske, Florian [Helmholtz-Zentrum Berlin fuer Materialien und Energie (HZB), Berlin (Germany)

    2010-07-01

    Transparent conductive oxides (TCOs) play a big role in display and photovoltaic technology. One of the most promising materials for photovoltaic applications is aluminum doped zinc oxide. The electrical properties of differently prepared ZnO:Al films will be analyzed in this paper. Carrier mobility and free carrier density are varying in a wide range depending on the preparation method and doping level. Reactive mid frequency magnetron sputtering of a metallic Zn:Al target, radio frequency and direct current magnetron sputtering of a ceramic ZnO:Al{sub 2}O{sub 3} target are considered as well as the post deposition annealing of samples, which increases mobility significantly. The carrier mobility in polycrystalline aluminum doped ZnO is limited by scattering at grain boundaries and at ionized impurities. With Hall and Seebeck measurements insight will be given in transport and scatter mechanisms for the different samples.

  2. Electric properties and fabrication of IMI-O LB films containing the imidazole group

    CERN Document Server

    Yoo, S Y; Kwon, Y S; Park, J C

    1999-01-01

    We fabricated an IMI-O polymer containing an imidazole group that could form a complex structure between the monolayer and the metal ions at the air-water interface. Also, the monolayer behavior at the air-water interface and the electrical properties of metal-complexed Langmuir-Blodgett (LB) films were investigated by using Brewster angle microscopy (BAM) and current-voltage(I-V) measurements. The difference in the BAM images between the pure water and the aqueous metal ions is attributed to the interactions of the copolymers with the metal ions at the interface and the consequent change of the monolayer organization. In the I-V characteristics, the current for LB films with different metal ion depended on the quantity of the metal-ion complexed with the LB film due to the interaction between the metal ion and the IMI-O polymer.

  3. Magnetic Properties and Electrical Resistivity of Zr4+ Substituted Li-Zn Ferrite

    Directory of Open Access Journals (Sweden)

    A. A. Sattar

    2007-01-01

    Full Text Available The effect of Zr-substitution on the physical and magnetic properties of Li0.3+0.5xZn0.4ZrxFe2.3-1.5xO4 ferrites (x=0.0, 0.01, 0.02, 0.03 and 0.05, prepared by the standard ceramic method, has been studied. It is found that the saturation magnetization increases up to x=0.02 and then it decreases. On the other hand, the initial permeability increased while the Curie temperature remained almost constant with increasing x. The behavior of coercivity and remanence ratio was discussed. The composition dependence of the dc electrical resistivity is found to support the hopping conduction mechanism.

  4. The Structural and Electrical Properties of Nanostructures ZnO Thin Films on Flexible Substrate

    Directory of Open Access Journals (Sweden)

    Nur Sa’adah Muhamad Sauki

    2017-06-01

    Full Text Available Zinc oxide (ZnO thin films were deposited on Teflon substrates by radio frequency (RF magnetron sputtering method at different substrate temperature. The dependence of residual stress on the substrate temperature was investigated in this work due to the growth process, the bombardment of energetic particles and process heating to the deposited thin films. From field emission scanning electron microscope (FESEM images, samples that deposited at various substrate temperatures consists nano-sized particles. The obtained X-ray diffraction (XRD results, it suggested that ZnO thin film deposited at 40oC with highly c-axis oriented shows unstressed film compared to other thin films. Besides that, the ZnO thin films deposited at 40oC shows improved electrical properties.

  5. Contact metal-dependent electrical transport in carbon nanotubes and fabrication of graphene nanoribbons

    Science.gov (United States)

    Perello, David

    In this thesis, we fabricate and characterize carbon nanotube (CNT) and graphene-based field effect transistor devices. The CNT-based work centers around the physics of metal contacts to CNT, particularly relating the work function of contact metals to carrier transport across the junction. The graphene work is motivated by the desire to utilize the high carrier mobility of graphene in field effect transistors. CNT have excellent electrical properties including high carrier mobility, large field effect switching capabilities, and a long mean free path. Absent, however is an experimentally-backed model explaining contact-metal work function, device layout, and environment effects. To fill this void, we introduce a surface-inversion channel (SIC) model based on low temperature and electrical measurements of a distinct single-walled semiconducting CNT contacted by Hf, Cr, Ti and Pd electrodes. Anomalous barrier heights and metal-contact dependent band-to-band tunneling phenomena are utilized to show that dependent upon contact work function and gate field, transport occurs either directly between the metal and CNT channel or indirectly via injection of carriers from the metal-covered CNT region to the CNT channel. The model is consistent with previously contradictory experimental results, and the methodology is simple enough to apply in other contact-dominant systems. In agreement with the initial contact theory above, we further develop a model explain Isd-Vsd tendencies in CNT FETs. Using experimental and analytical analysis, we demonstrate a relationship between the contact metal work function and electrical transport properties saturation current (Isat) and differential conductance ssd=6Isd 6Vsd in ambient exposed CNT. A single chemical vapor deposition (CVD)-grown 6 millimeter long semiconducting single-walled CNT is electrically contacted with a statistically significant number of Hf, Cr, Ti, Pd, and Ti, Au electrodes, respectively. The observed exponentially

  6. Structural, mechanical and electrical properties of alloys in ternary Ag-Bi-Zn system

    Energy Technology Data Exchange (ETDEWEB)

    Minic, D. M.; Premovic, M. M.; Zivkovic, D. T.; Manasijevic, D. M.; Dimie, M. Z.; Petrovic, Z. R.; Markovic, S. M.

    2015-07-01

    Structural, mechanical and electrical properties of selected alloys in ternary Ag-Bi-Zn system are presented in this paper. Chosen alloys were investigated using X-Ray Diffraction (XRD), light optical microscopy, Scanning Electron Microscopy combined with Energy Dispersive Spectrometry (SEM-EDS), as well as by electrical conductivity and Brinell hardness measurements. Isolines of electrical conductivity and hardness for the entire Ag-Bi-Zn system were calculated using regression models. (Author)

  7. Process dependent thermoelectric properties of EDTA assisted bismuth telluride

    Energy Technology Data Exchange (ETDEWEB)

    Kulsi, Chiranjit; Banerjee, Dipali, E-mail: dipalibanerjeebesu@gmail.com [Department of Physics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711103, West Bengal (India); Kargupta, Kajari [Chemical Engineering Department, Jadavpur University, Kolkata-700032, West Bengal (India)

    2016-04-13

    Comparison between the structure and thermoelectric properties of EDTA (Ethylene-diamine-tetra-acetic acid) assisted bismuth telluride prepared by electrochemical deposition and hydrothermal route is reported in the present work. The prepared samples have been structurally characterized by high resolution X-ray diffraction spectra (HRXRD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopic images (HRTEM). Crystallite size and strain have been determined from Williamson-Hall plot of XRD which is in conformity with TEM images. Measurement of transport properties show sample in the pellet form (S{sub 1}) prepared via hydrothermal route has higher value of thermoelectric power (S) than the electrodeposited film (S{sub 2}). But due to a substantial increase in the electrical conductivity (σ) of the film (S{sub 2}) over the pellet (S{sub 1}), the power factor and the figure of merit is higher for sample S{sub 2} than the sample S{sub 1} at room temperature.

  8. Temperature dependent electrical behaviour of Cu2SnS3 films

    Directory of Open Access Journals (Sweden)

    Sandra Dias

    2014-03-01

    Full Text Available The temperature dependent electrical properties of the dropcasted Cu2SnS3 films have been measured in the temperature range 140 K to 317 K. The log I versus √V plot shows two regions. The region at lower bias is due to electrode limited Schottky emission and the higher bias region is due to bulk limited Poole Frenkel emission. The ideality factor is calculated from the ln I versus V plot for different temperatures fitted with the thermionic emission model and is found to vary from 6.05 eV to 12.23 eV. This large value is attributed to the presence of defects or amorphous layer at the Ag / Cu2SnS3 interface. From the Richardson's plot the Richardson's constant and the barrier height were calculated. Owing to the inhomogeneity in the barrier heights, the Richardson's constant and the barrier height were also calculated from the modified Richardson's plot. The I-V-T curves were also fitted using the thermionic field emission model. The barrier heights were found to be higher than those calculated using thermionic emission model. From the fit of the I-V-T curves to the field emission model, field emission was seen to dominate in the low temperature range of 140 K to 177 K. The temperature dependent current graphs show two regions of different mechanisms. The log I versus 1000/T plot gives activation energies Ea1 = 0.367095 − 0.257682 eV and Ea2 = 0.038416 − 0.042452 eV. The log (I/T2 versus 1000/T graph gives trap depths Φo1 = 0.314159 − 0.204752 eV and Φo2 = 0.007425 − 0.011163 eV. With increasing voltage the activation energy Ea1 and the trap depth Φo1 decrease. From the ln (IT1/2 versus 1/T1/4 graph, the low temperature region is due to variable range hopping mechanism and the high temperature region is due to thermionic emission.

  9. A Study on Properties of Electrical Conductive Bricks for Direct Current Electrical Arc Furnace

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    In this expeiment,the effects of temperature and graphite content on the electricl conductivity of MgO-C materials are studied,Experimental results indicated:the proper ontent of graphite is 10%-12%,The specific electrical resistance of MgO-C materials tends to decrease as the preheat treatment temerature rises.After heat treatment,the specific electrical resistance of MgO-C materials is nearly independent of temperature.

  10. Strain Rate Dependency of Bronze Metal Matrix Composite Mechanical Properties as a Function of Casting Technique

    Science.gov (United States)

    Brown, Lloyd; Joyce, Peter; Radice, Joshua; Gregorian, Dro; Gobble, Michael

    2012-07-01

    Strain rate dependency of mechanical properties of tungsten carbide (WC)-filled bronze castings fabricated by centrifugal and sedimentation-casting techniques are examined, in this study. Both casting techniques are an attempt to produce a functionally graded material with high wear resistance at a chosen surface. Potential applications of such materials include shaft bushings, electrical contact surfaces, and brake rotors. Knowledge of strain rate-dependent mechanical properties is recommended for predicting component response due to dynamic loading or impact events. A brief overview of the casting techniques for the materials considered in this study is followed by an explanation of the test matrix and testing techniques. Hardness testing, density measurement, and determination of the volume fraction of WC particles are performed throughout the castings using both image analysis and optical microscopy. The effects of particle filling on mechanical properties are first evaluated through a microhardness survey of the castings. The volume fraction of WC particles is validated using a thorough density survey and a rule-of-mixtures model. Split Hopkinson Pressure Bar (SHPB) testing of various volume fraction specimens is conducted to determine strain dependence of mechanical properties and to compare the process-property relationships between the two casting techniques. The baseline performances of C95400 bronze are provided for comparison. The results show that the addition of WC particles improves microhardness significantly for the centrifugally cast specimens, and, to a lesser extent, in the sedimentation-cast specimens, largely because the WC particles are more concentrated as a result of the centrifugal-casting process. Both metal matrix composites (MMCs) demonstrate strain rate dependency, with sedimentation casting having a greater, but variable, effects on material response. This difference is attributed to legacy effects from the casting process, namely

  11. Electrical properties of methane hydrate + sediment mixtures: The σ of CH4 Hydrate + Sediment

    Energy Technology Data Exchange (ETDEWEB)

    Du Frane, Wyatt L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Stern, Laura A. [U. S. Geological Survey, Menlo Park, CA (United States); Constable, Steven [Scripps Institution of Oceanography, La Jolla, CA (United States); Weitemeyer, Karen A. [Scripps Institution of Oceanography, La Jolla, CA (United States); National Oceanography Centre Southampton (United Kingdom), Univ. of Southampton Waterfront Campus, Southampton (United Kingdom); Smith, Megan M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Roberts, Jeffery J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-07-30

    Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. We built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (σ) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EM field surveys. We report σ measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low σ but is found to increase the overall σ of mixtures with well-connected methane hydrate. Alternatively, the overall σ decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. Finally, these results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems.

  12. Correlation between Electrical Properties and Potentiometric Response of CS-Clay Nanocomposite Membranes

    Directory of Open Access Journals (Sweden)

    M. Oviedo Mendoza

    2015-01-01

    Full Text Available The aim of this work is to study the relationship between electrical, structure, and potentiometric response to nitrate anions using Ion Selective Electrodes (ISE. These ISE are based on chitosan-montmorillonite nanocomposite membranes with different content of montmorillonite. Membrane properties have been studied using SEM, FTIR, and impedance spectroscopy measurements. With the advent of impedance spectroscopy one is allowed to obtain the DC conductivity dependence on montmorillonite concentration and the percolation threshold. Additionally, the potentiometric response to nitrate anions of ISE based on chitosan-clay nanocomposite has been investigated. It is shown that the properties and performance of these membrane electrodes depend upon the clay wt% and that the best sensitivity to nitrate ions (with detection limit 7 × 10−5 M is obtained near the percolation concentration ca. 8 ± 2.5 wt% of clay. This observation is traceable to higher clay content (higher agglomeration that tends to decrease the intercalation and absorption of the number of chitosan chains in the interlayer space of montmorillonite.

  13. Polyaniline/carbon nanotube/CdS quantum dot composites with enhanced optical and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Mrinmoy [Department of Physics, National Institute of Technology, Durgapur, 713209 (India); Ghosh, Ranajit, E-mail: ghosh.ranajit@gmail.com [CSIR-Central Mechanical Engineering Research Institute, Durgapur, 713209 (India); Maruyama, Takahiro [Department of Applied Chemistry, Meijo University, Nagoya, 4688502 (Japan); Meikap, Ajit Kumar [Department of Physics, National Institute of Technology, Durgapur, 713209 (India)

    2016-02-28

    Graphical abstract: - Highlights: • A new kind of polyaniline/carbon nanotube/CdS quantum dot composites have been synthesized via in-situ polymerization of aniline monomer. • A degree of increase in conductivity. • Size-dependent optical properties of CdS quantum dots have been observed. - Abstract: A new kind of polyaniline/carbon nanotube/CdS quantum dot composites have been developed via in-situ polymerization of aniline monomer in the presence of dispersed CdS quantum dots (size: 2.7–4.8 nm) and multi-walled carbon nanotubes (CNT), which exhibits enhanced optical and electrical properties. The existences of 1st order, 2nd order, and 3rd order longitudinal optical phonon modes, strongly indicate the high quality of synthesized CdS quantum dots. The occurrence of red shift of free exciton energy in photoluminescence is due to size dependent quantum confinement effect of CdS. The conductivity of the composites (for example PANI/CNT/CdS (2 wt.% CdS)) is increased by about 7 of magnitude compared to that of pure PANI indicating a charge transfer between CNT and polymer via CdS quantum dots. This advanced material has a great potential for high-performance of electro-optical applications.

  14. Study of Time-Dependent Properties of Thermoplastics

    Directory of Open Access Journals (Sweden)

    Bolchoun A.

    2010-06-01

    Full Text Available Simple tests carried out with a common tension/compression testing machine are used to obtain timedependent properties of non-reinforced thermoplastics. These tests include ramp loadings as well as relaxation and creep tests. Two materials (PBT Celanex 2002-2 and POM Hostaform C9021, Ticona GmbH, Kelsterbach were taken for the experiments. The experiments show that an adequate description of the long-term material properties can be obtained from the short-time tests, namely from tests with constant traverse speed $L^.$. Below a model for the time-dependent mechanical behavior is presented and fitted to the obtained measured data. For the evaluation of the fitting quality long-term tests are used. Especially creep and relaxation tests with ”jumps”, i.e. rapid change of loading, are important for this purpose.

  15. STRUCTURE AND PROPERTIES OF POWDER STEELS SINTERED BY ELECTRIC CONTACT HEATING

    Directory of Open Access Journals (Sweden)

    Florin CIOFU

    2016-12-01

    Full Text Available Test equipment is constructed and technology is developed for electric contact sintering of specimens based on iron. The structure and properties of specimens after sintering is studied by metallographic. It is established that the structure of these specimens is ferrite-bainite-martensite with predominance of the martensitic phase. After electric sintering there are considerable microstresses in the material that increase with an increase in carbon content. A considerable number of randonomly arranged dislocations are revealed in sintered samples that are more numerous by two orders of magnitude or more than the number of boundary dislocations. This should be appear in the mechanical properties of sintered specimens. Comparasion of the structure and properties of samples of the same composition sintered by electric contactmethod shows a small difference in these properties. Thus the electric sintering technology developed by us for samples may with appropriate development be introduced into production.

  16. A Study of the Properties of Electrical Insulation Oils and of the Components of Natural Oils

    Directory of Open Access Journals (Sweden)

    Milan Spohner

    2012-01-01

    Full Text Available This paper presents a study of the electrical and non-electrical properties of insulating oils. For the correct choice of an electrical insulation oil, it is necessary to know its density, dynamic viscosity, dielectric constant, loss number and conductivity, and the effects of various exposure factors. This paper deals with mathematical and physical principles needed for studying and making correct measurements of the dynamic viscosity, density and electrical properties of insulation oils. Rheological properties were measured using an A&D SV-10 vibratory viscometer, and analytical balance with density determination kit, which operates on the principle of Archimedes’ law. Dielectric properties were measured using a LCR meter Agilent 4980A with connected with the Agilent 16452A test fixture for dielectric liquids.

  17. Closed-orbit theory for photodetachment in a time-dependent electric field

    CERN Document Server

    Yang, B C

    2016-01-01

    The standard closed-orbit theory is extended for the photodetachment of negative ions in a time-dependent electric field. The time-dependent photodetachment rate is specifically studied in the presence of a single-cycle terahertz pulse, based on exact quantum simulations and semiclassical analysis. We find that the photodetachment rate is unaffected by a weak terahertz field, but oscillates complicatedly when the terahertz pulse gets strong enough. Three types of closed classical orbits are identified for the photoelectron motion in a strong single-cycle terahertz pulse, and their connections with the oscillatory photodetachment rate are established quantitatively by generalizing the standard closed-orbit theory to a time-dependent form. By comparing the negative hydrogen and fluorine ions, both the in-phase and antiphase oscillations can be observed, depending on a simple geometry of the contributed closed classical orbits. On account of its generality, the presented theory provides an intuitive understandin...

  18. Quark mass dependence of quarkonium properties at finite temperature

    CERN Document Server

    Ohno, H; Kaczmarek, O

    2014-01-01

    Quarkonium properties at finite temperature have been studied with quark masses of the charm and bottom quarks. Our simulations have been performed in quenched QCD with the $O(a)$-improved Wilson quarks on large and fine isotropic lattices with the spatial lattice extents $N_\\sigma =$ 96, 192 and the corresponding lattice spacings $a =$ 0.0190, 0.00967 fm, respectively, at temperatures in a range between about 0.7$T_c$ and 1.4$T_c$. We show temperature and quark mass dependence of quarkonium correlation functions and related physical quantities: the quark number susceptibility and the heavy quark diffusion constant.

  19. Biological and electrical properties of biosynthesized silver nanoparticles

    Indian Academy of Sciences (India)

    Madhulika Bhagat; Shayana Rajput; Sandeep Arya; Saleem Khan; Parveen Lehana

    2015-09-01

    In this work, silver nanoparticles (AgNPs) were synthesized biochemically at room temperature using aqueous extract of rhizome of Rheum australe plant. The as-synthesized AgNPs were further studied for their morphological, biological and electrical characterization. The morphological studies, such as scanning electron microscopy, X-ray diffraction and UV–vis spectrum confirmed their successful synthesis. Biological analysis revealed their antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Electrical characterization showed that the conductivity of the mixture of AgNPs with DPPH assay is more than the AgNPs dispersed in distilled water. The obtained results may have potential applications as sensors.

  20. Electrical modulation of static and dynamic spectroscopic properties of coupled nanoscale GaSe quantum dot assemblies

    Science.gov (United States)

    Verma, Y. K.; Inman, R. H.; Ferri, C. G. L.; Mirafzal, H.; Ghosh, S. N.; Kelley, D. F.; Hirst, L. S.; Ghosh, S.; Chin, W. C.

    2010-10-01

    We demonstrate the formation and spatial modulation of strongly coupled gallium selenide quantum dot (QD) nanoassemblies suspended in a nematic liquid-crystal (NLC) matrix at room temperature. Using static and dynamic optical techniques we show that the coupled QDs aggregate with a well-defined directionality commensurate with the NLC director axis. This results in highly anisotropic spectral properties of the QD assembly. The spatial orientation of the aggregates is selectively controlled in situ by the application of in-plane electric fields. The strong interdot coupling further increases the excitonic recombination rate which is both direction and electric field dependent. This electrical modulation, a noninvasive process, could potentially be an important functionality for the design and creation of building blocks for novel optoelectronic devices.

  1. Influence of air annealing on the structural, morphological, optical and electrical properties of chemically deposited ZnSe thin films

    Science.gov (United States)

    Kale, R. B.; Lokhande, C. D.

    2005-11-01

    Zinc selenide nanocrystalline thin films are grown onto amorphous glass substrate from an aqueous alkaline medium, using chemical bath deposition (CBD) method. The ZnSe thin films are annealed in air for 4 h at various temperatures and characterized by structural, morphological, optical and electrical properties. The as-deposited ZnSe film grew with nanocrystalline cubic phase alongwith some amorphous phase present in it. After annealing metastable nanocrystalline cubic phase was transformed into stable polycrystalline hexagonal phase with partial conversion of ZnSe into ZnO. The optical band gap, Eg, of as-deposited film is 2.85 eV and electrical resistivity of the order of 10 6-10 7 Ω cm. Depending upon annealing temperature, decrease up to 0.15 eV and 10 2 Ω cm were observed in the optical band gap, Eg, and electrical resistivity, respectively.

  2. Barium carbonate as an agent to improve the electrical properties of neodymium-barium-copper system at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.P. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Duarte, G.W. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Research Group in Technology and Information, Centro Universitário Barriga Verde (UNIBAVE), Santa Catarina, SC (Brazil); Caldart, C. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Kniess, C.T. [Post-Graduate Program in Professional Master in Management, Universidade Nove de Julho, São Paulo, SP (Brazil); Montedo, O.R.K.; Rocha, M.R. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarinense (UNESC), Criciúma, SC, 88806-000 (Brazil); Riella, H.G. [Post-Graduate Program in Chemical Engineering, Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, 88040-900 (Brazil); Fiori, M.A., E-mail: fiori@unochapeco.edu.br [Post-Graduate Program in Environmental Science, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil); Post-Graduate Program in Technology and Management of the Innovation, Universidade Comunitária da Região de Chapecó (UNOCHAPECÓ), Chapecó, SC, 89809-000 (Brazil)

    2015-11-15

    Specialized ceramics are manufactured under special conditions and contain specific elements. They possess unique electrical and thermal properties and are frequently used by the electronics industry. Ceramics containing neodymium-barium-copper (NBC) exhibit high conductivities at low temperatures. NBC-based ceramics are typically combined with oxides, i.e., NBCo produced from neodymium oxide, barium oxide and copper oxide. This study presents NBC ceramics that were produced with barium carbonate, copper oxide and neodymium oxide (NBCa) as starting materials. These ceramics have good electrical conductivities at room temperature. Their conductivities are temperature dependent and related to the starting amount of barium carbonate (w%). - Highlights: • The new crystalline structure were obtained due presence of the barium carbonate. • The NBCa compound has excellent electrical conductivity at room temperature. • The grain crystalline morphology was modified by presence of the barium carbonate. • New Phases α and β were introduced by carbonate barium in the NBC compound.

  3. Magnetic Resonance Based Electrical Property Tomography (MR-EPT) for Prostate Cancer Grade Imaging

    Science.gov (United States)

    2015-07-01

    S. Akoka, F. Franconi, F. Seguin, and A. Le Pape, “Radiofrequency map of an NMR coil by imaging,” Magnetic resonance imaging, vol. 11, no. 3, pp. 437...AD_________________ Award Number: W81XWH-13-1-0127 TITLE: “ Magnetic Resonance -Based Electrical Property Tomography (MR- EPT) for Prostate Cancer...2014 – June 30, 2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER W81XWH-13-1-0127 Magnetic Resonance -Based Electrical Property Tomography (MR- EPT

  4. Cellular Automata Simulations of Thermal and Electrical Transport Properties of Thin-Film Polymer/CNTs Nanocomposites

    Science.gov (United States)

    Casey, Alex; Iannacchione, Germano; Georgiev, Georgi; Cebe, Peggy

    2014-03-01

    A computational algorithm has been developed to simulate the transport properties of oriented and un-oriented thin film nanocomposites of isotactic Polypropylene (iPP) and carbon nanotubes (CNT) with increasing CNT concentration. Our goal is to be able to design materials with optimal properties using simulations. We use cellular automata approach in Matlab simulation environment. The percolation threshold is reproduced in the simulations, matching experimental data. Upon percolation, the thermal transport in the films increases sharply, more so for the electrical than for the thermal conductivity, due to the larger difference in the electric conductivities of the CNTs and the polymer. To verify the simulation, the thin-film samples were sheared in the melt at 200 C at 1 Hz in a Linkan microscope shearing hot stage. The thermal and electrical conductivity measurements were performed on the same cell arrangement with the transport perpendicular to the thin-film plane using a DC method. The thermal and electrical conductivity are higher for the un-sheared as compared to the sheared samples with stronger temperature dependence for the latter as compared to the former. Our cellular automata simulations provide information about the microstructure-macroscopic property relation in the thin film nanocomposites and can be extended to simulations of other important materials.

  5. Enhancement of the electrical properties of graphene grown by chemical vapor deposition via controlling the effects of polymer residue.

    Science.gov (United States)

    Suk, Ji Won; Lee, Wi Hyoung; Lee, Jongho; Chou, Harry; Piner, Richard D; Hao, Yufeng; Akinwande, Deji; Ruoff, Rodney S

    2013-04-10

    Residual polymer (here, poly(methyl methacrylate), PMMA) left on graphene from transfer from metals or device fabrication processes affects its electrical and thermal properties. We have found that the amount of polymer residue left after the transfer of chemical vapor deposited (CVD) graphene varies depending on the initial concentration of the polymer solution, and this residue influences the electrical performance of graphene field-effect transistors fabricated on SiO2/Si. A PMMA solution with lower concentration gave less residue after exposure to acetone, resulting in less p-type doping in graphene and higher charge carrier mobility. The electrical properties of the weakly p-doped graphene could be further enhanced by exposure to formamide with the Dirac point at nearly zero gate voltage and a more than 50% increase of the room-temperature charge carrier mobility in air. This can be attributed to electron donation to graphene by the -NH2 functional group in formamide that is absorbed in the polymer residue. This work provides a route to enhancing the electrical properties of CVD-grown graphene even when it has a thin polymer coating.

  6. Structural and electrical properties of annealed CdSe films on Ni substrate

    Energy Technology Data Exchange (ETDEWEB)

    Athanassopoulou, M.D.; Mergos, J.A.; Palaiologopoulou, M.D.; Argyropoulos, Th.G.; Dervos, C.T., E-mail: cdervos@central.ntua.gr

    2012-08-31

    Preparation and characterization of CdSe thin film semiconductors, prepared by cathodic electrodeposition from an acid sulphate solution (CdSO{sub 4}-SeO{sub 2}) before and after thermal treatment in nitrogen atmosphere, were investigated. The effect of the bath temperature and how it affects the cadmium selenide (CdSe) deposits were studied. The formation of compact barrier layers of zinc blende CdSe was attained. Scanning electron microscopy and X-ray diffraction patterns present a remarkably intense cubic structure, even after thermal treatment. The Ni/CdSe/Au structure may exhibit rectifying properties depending on the temperature during the electrodeposition. Thermal annealing in nitrogen gas increases the conductivity of CdSe and intensifies the rectification properties of the Ni/CdSe/Au structure. - Highlights: Black-Right-Pointing-Pointer High quality (111) CdSe films by electrolytic deposition on Ni substrates. Black-Right-Pointing-Pointer Investigation of optimum film growth parameters during the electrodeposition. Black-Right-Pointing-Pointer Electrical characterization and rectification properties of Ni/CdSe/Au structures. Black-Right-Pointing-Pointer Thermal annealing in nitrogen gas, to investigate changes induced on deposits. Black-Right-Pointing-Pointer Conductivity of CdSe and potential barriers are controlled by annealing.

  7. Fabrication and Characterization of n-ZnO Hexagonal Nanorods/p-Si Heterojunction Diodes: Temperature-Dependant Electrical Characteristics.

    Science.gov (United States)

    Umar, Ahmad; Badran, R I; Al-Hajry, A; Al-Heniti, S

    2015-07-01

    This paper reports the temperature-dependant electrical characteristics of n-ZnO hexagonal nanorods/p-Si heterojunction diodes. The n-ZnO hexagonal nanorods were grown on p-Si substrate by a simple thermal evaporation process using metallic zinc powder in the presence of oxygen. The spectroscopic characterization revealed well-crystalline nanorods, quasi-aligned to the substrate and possessing hexagonal shape. The as-grown nanorods exhibited a strong near-band-edge emis- sion with very weak deep-level emission in the room-temperature photoluminescence spectrum, confirming good optical properties. Furthermore, the electrical properties of as-grown ZnO nanorods were examined by fabricating n-ZnO/p-Si heterojunction assembly and the I-V characteristics of the fabricated heterojunction assembly were investigated at different temperatures. The fabricated n-ZnO/p-Si heterojunction diodes exhibited a turn-on voltage of ~5 V at different temperatures with a mean built-in-potential barrier of 1.12 eV. Moreover, the high values of quality factor obtained from I-V analysis suggested a non-ideal behavior of Schottky junction.

  8. Poisson-Boltzmann continuum-solvation models: applications to pH-dependent properties of biomolecules.

    Science.gov (United States)

    Antosiewicz, Jan M; Shugar, David

    2011-11-01

    All molecules can be viewed as either discrete or continuous assemblies of electric charges, and electrostatics plays a major role in intermolecular and intramolecular interactions. Moreover, charge distribution within molecules may fluctuate due to the presence of ionizable groups capable of exchanging protons with the environment, leading to pH-dependence of phenomena involving such molecules. Electrostatic aspects of complex shapes and environments of biological molecules, in vitro and in vivo, are relatively well amenable to treatment by Poisson-Boltzmann models, which are attractive in that they possess a clear physical meaning, and can be readily solved by several mathematically sound methods. Here we describe applications of these models to obtain valuable insights into some biologically important pH-dependent properties of biomolecules, such as stability, binding of ligands (including potential drugs), enzymatic activity, conformational transitions, membrane transport and viral entry.

  9. TNF-α provokes electrical abnormalities in rat atrial myocardium via a NO-dependent mechanism.

    Science.gov (United States)

    Abramochkin, Denis V; Kuzmin, Vladislav S; Mitrochin, Vadim M; Kalugin, Leonid; Dvorzhak, Anton; Makarenko, Ekaterina Y; Schubert, Rudolf; Kamkin, Andre

    2013-12-01

    Stretch-induced depolarizations of cardiomyocytes, which are related to activity of mechano-gated cation channels (MGCs), can lead to serious arrhythmias. However, signaling pathways leading to activation of mechano-gated channels by stretch remain almost unexplored. Using standard sharp microelectrodes, the present study addresses the hypothesis that tumor necrosis factor-alpha (TNF-α) modulates stretch-induced electrophysiological abnormalities in rat atrial myocardium by a mechanism involving nitric oxide (NO)-dependent pathways. TNF-α (50 ng/ml) produced a marked prolongation of action potential, subsequently transforming into humplike depolarizations and, finally, leading to occurrence of arrhythmias. These effects developed slowly during 25 min of TNF-α application. Similar electrical effects were induced by stretching the preparations. A blocker of MGCs, Gd(3+) (40 μM), completely abolished action potential (AP) prolongations and electrical abnormalities caused by TNF-α or stretch. Further, a donor of exogenous NO, S-nitroso-N-acetylpenicillamine SNAP (300 μM), evoked the same electrical abnormalities as TNF-α and tissue stretch. Both TNF-α and stretch failed to produce their typical effects after pretreatment of the preparations with the NO-synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME) (100 μM). Thus, the present study shows (i) that TNF-α and the NO-donor SNAP evoke MGC-mediated electrical abnormalities in rat atrial myocardium in the absence of stretch that is very similar to stretch-evoked electrical events and (ii) that the TNF-α-induced electrical abnormalities are mediated by NO synthase. In conclusion, our data suggest that NO is an endogenous modulator of MGCs and mediates proarrhythmic effects of TNF-α in mammalian organism.

  10. Electric and electrochemical properties of catalytically active oxygen electrode materials

    NARCIS (Netherlands)

    Burggraaf, A.J.; Dijk, van M.P.; Vries, de K.J.

    1986-01-01

    The electrical conductivity has been investigated of some oxygen ion and mixed conducting materials. Electrodes are prepared from thin sputtered layers of these oxides combined with a small Au or Pt strip. The kinetics of the oxygen reaction has been studied for temperatures of 820–1020 K and PO2 va

  11. Electrical properties of single p-hexaphenylene nanofibers

    DEFF Research Database (Denmark)

    Kjelstrup-Hansen, Jakob; Henrichsen, H.H.; Bøggild, Peter

    2006-01-01

    The electrical characteristics of individual para-hexaphenylene (p6P) nanofibers with typical widths of a few hundred nanometers and heights of a few ten nanometers are investigated. For that purpose we transfer the narofibers onto a lithographically patterned silicon oxide electrode support...

  12. Measurement of Thermal Dependencies of PBG Fiber Properties

    Energy Technology Data Exchange (ETDEWEB)

    Laouar, Rachik

    2011-07-06

    Photonic crystal fibers (PCFs) represent a class of optical fibers which have a wide spectrum of applications in the telecom and sensing industries. Currently, the Advanced Accelerator Research Department at SLAC is developing photonic bandgap particle accelerators, which are photonic crystal structures with a central defect used to accelerate electrons and achieve high longitudinal electric fields. Extremely compact and less costly than the traditional accelerators, these structures can support higher accelerating gradients and will open a new era in high energy physics as well as other fields of science. Based on direct laser acceleration in dielectric materials, the so called photonic band gap accelerators will benefit from mature laser and semiconductor industries. One of the key elements to direct laser acceleration in hollow core PCFs, is maintaining thermal and structural stability. Previous simulations demonstrate that accelerating modes are sensitive to the geometry of the defect region and the variations in the effective index. Unlike the telecom modes (for which over 95% of the energy propagates in the hollow core) most of the power of these modes is located in the glass at the periphery of the central hole which has a higher thermal constant than air ({gamma}{sub SiO{sub 2}} = 1.19 x 10{sup -6} 1/K, {gamma}{sub air} = -9 x 10{sup -7} 1/K with {gamma} = dn/dT). To fully control laser driven acceleration, we need to evaluate the thermal and structural consequences of such modes on the PCFs. We are conducting series of interferometric tests to quantify the dependencies of the HC-633-02 (NKT Photonics) propagation constant (k{sub z}) on temperature, vibration amplitude, stress and electric field strength. In this paper we will present the theoretical principles characterizing the thermal behavior of a PCF, the measurements realized for the fundamental telecom mode (TE{sub 00}), and the experimental demonstration of TM-like mode propagation in the HC-633

  13. Shape-dependent light scattering properties of subwavelength silicon nanoblocks.

    Science.gov (United States)

    Ee, Ho-Seok; Kang, Ju-Hyung; Brongersma, Mark L; Seo, Min-Kyo

    2015-03-11

    We explore the shape-dependent light scattering properties of silicon (Si) nanoblocks and their physical origin. These high-refractive-index nanostructures are easily fabricated using planar fabrication technologies and support strong, leaky-mode resonances that enable light manipulation beyond the optical diffraction limit. Dark-field microscopy and a numerical modal analysis show that the nanoblocks can be viewed as truncated Si waveguides, and the waveguide dispersion strongly controls the resonant properties. This explains why the lowest-order transverse magnetic (TM01) mode resonance can be widely tuned over the entire visible wavelength range depending on the nanoblock length, whereas the wavelength-scale TM11 mode resonance does not change greatly. For sufficiently short lengths, the TM01 and TM11 modes can be made to spectrally overlap, and a substantial scattering efficiency, which is defined as the ratio of the scattering cross section to the physical cross section of the nanoblock, of ∼9.95, approaching the theoretical lowest-order single-channel scattering limit, is achievable. Control over the subwavelength-scale leaky-mode resonance allows Si nanoblocks to generate vivid structural color, manipulate forward and backward scattering, and act as excellent photonic artificial atoms for metasurfaces.

  14. Structural, magnetic, electric, dielectric, and thermodynamic properties of multiferroic Ge V4S8

    Science.gov (United States)

    Widmann, S.; Günther, A.; Ruff, E.; Tsurkan, V.; Krug von Nidda, H.-A.; Lunkenheimer, P.; Loidl, A.

    2016-12-01

    The lacunar spinel Ge V4S8 undergoes orbital and ferroelectric ordering at the Jahn-Teller transition around 30 K and exhibits antiferromagnetic order below about 14 K. In addition to this orbitally driven ferroelectricity, lacunar spinels are an interesting material class, as the vanadium ions form V4 clusters representing stable molecular entities with a common electron distribution and a well-defined level scheme of molecular states resulting in a unique spin state per V4 molecule. Here we report detailed x-ray, magnetic susceptibility, electrical resistivity, heat capacity, thermal expansion, and dielectric results to characterize the structural, electric, dielectric, magnetic, and thermodynamic properties of this interesting material, which also exhibits strong electronic correlations. From the magnetic susceptibility, we determine a negative Curie-Weiss temperature, indicative for antiferromagnetic exchange and a paramagnetic moment close to a spin S =1 of the V4 molecular clusters. The low-temperature heat capacity provides experimental evidence for gapped magnon excitations. From the entropy release, we conclude about strong correlations between magnetic order and lattice distortions. In addition, the observed anomalies at the phase transitions also indicate strong coupling between structural and electronic degrees of freedom. Utilizing dielectric spectroscopy, we find the onset of significant dispersion effects at the polar Jahn-Teller transition. The dispersion becomes fully suppressed again with the onset of spin order. In addition, the temperature dependencies of dielectric constant and specific heat possibly indicate a sequential appearance of orbital and polar order.

  15. Electric Heating Property from Butyl Rubber-Loaded Boron Carbide Composites

    Institute of Scientific and Technical Information of China (English)

    MENG Dechuan; WANG Ninghui; LI Guofeng

    2014-01-01

    We researched the electric heating property from butyl rubber-loaded boron carbide composite. The effects of boron carbide content on bulk resistivity, voltage-current characteristic, thermal conductivity and thermal stability of boron carbide/butyl rubber (IIR) polymer composite were introduced. The analysis results indicated that the bulk resistivity decreased greatly with increasing boron carbide content, and when boron carbide content reached to 60%, the bulk resistivity achieved the minimum. Accordingly, electric heating behavior of the composite is strongly dependent on boron carbide content as well as applied voltage. The content of boron carbide was found to be effective in achieving high thermal conductivity in composite systems. The thermal conductivity of the composite material with added boron carbide was improved nearly 20 times than that of the pure IIR. The thermal stability test showed that, compared with pure IIR, the thermal stable time of composites was markedly extended, which indicated that the boron carbide can significantly improve the thermal stability of boron carbide/IIR composite.

  16. Structural, magnetic and electrical properties of CuZn ferrite nanopowders

    Science.gov (United States)

    Li, Le-Zhong; Peng, Long; Zhong, Xiao-Xi; Wang, Rui; Tu, Xiao-Qiang

    2016-12-01

    Zn-substituted Cu ferrite nanopowders, Cu1-xZnxFe2O4 (0≤x≤1.0), were synthesized by the sol-gel auto-combustion method. The effect of Zn substitution on the structural, magnetic and electrical properties have been investigated. The DTA and TG results indicate that there are three steps of combustion process. The X-ray diffraction patterns show that there are Fe2O3, CuO and CuFeO2 secondary phases and tetragonal structure when x=0.0. Furthermore, the lattice parameter and the average crystallite size decrease, and the X-ray density increases with the increase of Zn substitution. The saturation magnetization increases with the increase of Zn substitution when x≤0.40, and decreases when x>0.40. Meanwhile, the coercivity monotonically decreases with the increase of Zn substitution. The polarization behavior for all the samples in the test frequency range of 100 Hz to 10 MHz obeys the charge polarization mechanism. Electrical transport behavior of the ferrites nanopowders is same with the impurity semiconductor, and the effect of Zn substitution on the temperature dependence of dc resistivity is observed.

  17. Thermal stability and electrical properties of copper nitride with In or Ti

    Science.gov (United States)

    Du, Yun; Gao, Lei; Li, Chao-Rong; Ji, Ai-Ling

    2013-06-01

    Thin films of ternary compounds CuxInyN and CuxTiyN were grown by magnetron sputtering to improve the thermal stability of Cu3N, a material that decomposes below 300 °C, and thus promises many interesting applications in direct-writing. The effect of In or Ti incorporation in altering the structure and physical properties of copper nitride was evaluated by characterizing the film structure, surface morphology, and temperature dependence of electrical resistivity. More Ti than In can be accommodated by copper nitride without completely deteriorating the Cu3N lattice. A small amount of In or Ti can improve the crystallinity, and consequently the surface morphology. While the decomposition temperature is rarely influenced by In, the Ti-doped sample, Cu59.31Ti2.64N38.05, shows an X-ray diffraction pattern dominated by characteristic Cu3N peaks, even after annealing at 500 °C. Both In and Ti reduce the bandgap of the original Cu3N phase, resulting in a smaller electrical resistivity at room temperature. The samples with more Ti content manifest metal-semiconductor transition when cooled from room temperature down to 50 K. These results can be useful in improving the applicability of copper—nitride-based thin films.

  18. Thickness and microstructure effects in the optical and electrical properties of silver thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Guowen, E-mail: gding@intermolecular.com; Clavero, César; Schweigert, Daniel; Le, Minh [Intermolecular, Inc., 3011 North First Street, San Jose, CA 95134 (United States)

    2015-11-15

    The optical and electrical response of metal thin films approaching thicknesses in the range of the electron mean free path is highly affected by electronic scattering with the interfaces and defects. Here, we present a theoretical and experimental study on how thickness and microstructure affect the properties of Ag thin films. We are able to successfully model the electrical resistivity and IR optical response using a thickness dependent electronic scattering time. Remarkably, the product of electronic scattering time and resistivity remains constant regardless of the thickness (τx ρ = C), with a value of 59 ± 2 μΩ cm ⋅ fs for Ag films in the investigated range from 3 to 74 nm. Our findings enable us to develop a theoretically framework that allows calculating the optical response of metal thin films in the IR by using their measured thickness and resistivity. An excellent agreement is found between experimental measurements and predicted values. This study also shows the theoretical lower limit for emissivity in Ag thin films according to their microstructure and thickness. Application of the model presented here will allow rapid characterization of the IR optical response of metal thin films, with important application in a broad spectrum of fundamental and industrial applications, including optical coatings, low-emissivity windows and semiconductor industry.

  19. Thickness and microstructure effects in the optical and electrical properties of silver thin films

    Directory of Open Access Journals (Sweden)

    Guowen Ding

    2015-11-01

    Full Text Available The optical and electrical response of metal thin films approaching thicknesses in the range of the electron mean free path is highly affected by electronic scattering with the interfaces and defects. Here, we present a theoretical and experimental study on how thickness and microstructure affect the properties of Ag thin films. We are able to successfully model the electrical resistivity and IR optical response using a thickness dependent electronic scattering time. Remarkably, the product of electronic scattering time and resistivity remains constant regardless of the thickness (τx ρ = C, with a value of 59 ± 2 μΩ cm ⋅ fs for Ag films in the investigated range from 3 to 74 nm. Our findings enable us to develop a theoretically framework that allows calculating the optical response of metal thin films in the IR by using their measured thickness and resistivity. An excellent agreement is found between experimental measurements and predicted values. This study also shows the theoretical lower limit for emissivity in Ag thin films according to their microstructure and thickness. Application of the model presented here will allow rapid characterization of the IR optical response of metal thin films, with important application in a broad spectrum of fundamental and industrial applications, including optical coatings, low-emissivity windows and semiconductor industry.

  20. Enhancement in electrical properties of ITO/PEDOT:PSS/PTCDA/Ag by using calcium buffer layer

    Science.gov (United States)

    Tahir, Muhammad; Hassan Sayyad, Muhammad; Wahab, Fazal; Aziz, Fakhra; Ullah, Irfan; Khan, Gulzar

    2015-06-01

    This paper reports on electrical characterization of ITO/PEDOT:PSS/PTCDA/Ca/Ag device based on 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) and calcium (Ca) buffer layer with improved junction properties. The I-V characteristics have been utilized to extract various electrical parameters such as ideality factor (n), barrier height (ϕB) and series resistance Rs, which are found to be 1.9, 0.79 eV and 2.5 kΩ, respectively. The device shows good rectifying behavior, with a rectification ratio of 528, and also field-lowering mechanism with a linear dependence of log I on V1/2. The device reported in the present work shows 50% improvement in the rectification ratio and ideality factor as compared to our previously fabricated device. It appears from the experimental data that the transport mechanism in the PTCDA thin film is dominated by the Poole-Frenkel model of thermionic emission, which may be associated with high density of structural defects or traps present in the film.

  1. Enhancement in electrical properties of ITO/PEDOT:PSS/PTCDA/Ag by using calcium buffer layer

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, Muhammad [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology Topi, KPK 23640 (Pakistan); Department of Physics, Abdul Wali Khan University Mardan, 23200 KPK (Pakistan); Hassan Sayyad, Muhammad [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology Topi, KPK 23640 (Pakistan); Wahab, Fazal [Department of Physics, Abdul Wali Khan University Mardan, 23200 KPK (Pakistan); Aziz, Fakhra, E-mail: fakhra69@yahoo.com [Department of Electronics, Jinnah College for Women, University of Peshawar, Peshawar 25120 (Pakistan); Ullah, Irfan; Khan, Gulzar [Department of Physics, Abdul Wali Khan University Mardan, 23200 KPK (Pakistan)

    2015-06-15

    This paper reports on electrical characterization of ITO/PEDOT:PSS/PTCDA/Ca/Ag device based on 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) and calcium (Ca) buffer layer with improved junction properties. The I–V characteristics have been utilized to extract various electrical parameters such as ideality factor (n), barrier height (ϕ{sub B}) and series resistance R{sub s}, which are found to be 1.9, 0.79 eV and 2.5 kΩ, respectively. The device shows good rectifying behavior, with a rectification ratio of 528, and also field-lowering mechanism with a linear dependence of log I on V{sup 1/2}. The device reported in the present work shows 50% improvement in the rectification ratio and ideality factor as compared to our previously fabricated device. It appears from the experimental data that the transport mechanism in the PTCDA thin film is dominated by the Poole–Frenkel model of thermionic emission, which may be associated with high density of structural defects or traps present in the film.

  2. Effect of compositional variation on the electrical properties of Se-Te-Bi-Ag glassy alloy

    Science.gov (United States)

    Kumar, Anup; Heera, Pawan; Sharma, Raman

    2015-05-01

    In this paper we have studied the effect of Ag addition on electrical properties of Se80.5Bi1.5Te18-yAgy (y = 1.0, 1.5 and 2.0 at. %) glassy system by using digital picometer (Keithley, model 6487) in the voltage range 0-300V. I-V study reveals that the glassy alloys under study exhibit ohmic behavior at low voltage and non-ohmic at high voltage. The field dependence studies for pellets reveal the ohmic nature of current for voltage less than 60V and non-ohmic nature of current for voltage greater than 60V. At higher voltage, greater than 60V, thermal effects come into plays which result in an increase in electrical conductivity. The d.c. conductivity is found to increase with an increase in Ag content. The conduction mechanism is discussed in terms of Poole-Frenkel conduction mechanism. The linearity of the plots between ln(I) and V1/2 shows that the conduction mechanism in the higher voltage range is of Poole-Frenkel type.

  3. Structural and electrical properties of electric field assisted spray deposited pea structured ZnO film

    Science.gov (United States)

    Chaturvedi, Neha; Swami, Sanjay Kumar; Dutta, Viresh

    2016-05-01

    Spray deposition of ZnO film was carried out. The uneven growth of ZnO nanostructures is resulted for spray deposited ZnO film. Application of DC voltage (1000V) during spray deposition provides formation of pea like structures with uniform coverage over the substrate. Electric field assisted spray deposition provides increased crystallinity with reduced resistivity and improved mobility of the ZnO film as compared to spray deposited ZnO film without electric field. This with large area deposition makes the process more efficient than other techniques.

  4. Effect of substrate temperature on structural, morphological, optical and electrical properties of IGZO thin films

    Science.gov (United States)

    Jayaraman, Vinoth Kumar; Álvarez, Arturo Maldonado; Olvera Amador, María de la luz

    2017-02-01

    Indium and gallium co-doped zinc oxide (IGZO) thin films were deposited on glass substrates by ultrasonic spray pyrolysis. Physical properties such as structural, morphological, optical and electrical properties were examined on IGZO thin films with respect to the changes in the substrate temperature (425, 450 and 475 °C). Structural results showed that IGZO films were crystalline and presented hexagonal wurtzite structure. Morphological studies proved that the substrate temperature changed the sizes of hexagonal nanostructures of IGZO. Optical transmittance in the UV-vis region and electrical measurements confirmed that IGZO films were transparent (>70%) with a minimum electrical resistivity 10.5×10-3 Ω cm.

  5. Light irradiation tuning of surface wettability, optical, and electric properties of graphene oxide thin films

    Science.gov (United States)

    Furio, A.; Landi, G.; Altavilla, C.; Sofia, D.; Iannace, S.; Sorrentino, A.; Neitzert, H. C.

    2017-02-01

    In this work the preparation of flexible polymeric films with controlled electrical conductivity, light transmission and surface wettability is reported. A drop casted graphene oxide thin film is photo-reduced at different levels by UV light or laser irradiation. Optical microscopy, IR spectroscopy, electrical characterization, Raman spectroscopy and static water contact angle measurements are used in order to characterize the effects of the various reduction methods. Correlations between the optical, electrical and structural properties are reported and compared to previous literature results. These correlations provide a useful tool for independently tuning the properties of these films for specific applications.

  6. The vestibular implant: Frequency-dependency of the electrically evoked Vestibulo-Ocular Reflex in humans

    Directory of Open Access Journals (Sweden)

    Raymond eVan De Berg

    2015-01-01

    Full Text Available The Vestibulo-Ocular Reflex (VOR shows frequency-dependent behavior. This study investigated whether the characteristics of the electrically evoked VOR (eVOR elicited by a vestibular implant, showed the same frequency-dependency.Twelve vestibular electrodes implanted in 7 patients with bilateral vestibular hypofunction were tested. Stimuli consisted of amplitude-modulated electrical stimulation with a sinusoidal profile at frequencies of 0.5Hz, 1Hz, and 2Hz. The main characteristics of the eVOR were evaluated and compared to the natural VOR characteristics measured in a group of age-matched healthy volunteers who were subjected to horizontal whole body rotations with equivalent sinusoidal velocity profiles at the same frequencies.A strong and significant effect of frequency was observed in the total peak eye velocity of the eVOR. This effect was similar to that observed in the natural VOR. Other characteristics of the (eVOR (angle, habituation-index, and asymmetry showed no significant frequency-dependent effect. In conclusion, this study demonstrates that, at least at the specific (limited frequency range tested, responses elicited by a vestibular implant closely mimic the frequency-dependency of the normal vestibular system.

  7. The vestibular implant: frequency-dependency of the electrically evoked vestibulo-ocular reflex in humans.

    Science.gov (United States)

    van de Berg, Raymond; Guinand, Nils; Nguyen, T A Khoa; Ranieri, Maurizio; Cavuscens, Samuel; Guyot, Jean-Philippe; Stokroos, Robert; Kingma, Herman; Perez-Fornos, Angelica

    2014-01-01

    The vestibulo-ocular reflex (VOR) shows frequency-dependent behavior. This study investigated whether the characteristics of the electrically evoked VOR (eVOR) elicited by a vestibular implant, showed the same frequency-dependency. Twelve vestibular electrodes implanted in seven patients with bilateral vestibular hypofunction (BVH) were tested. Stimuli consisted of amplitude-modulated electrical stimulation with a sinusoidal profile at frequencies of 0.5, 1, and 2 Hz. The main characteristics of the eVOR were evaluated and compared to the "natural" VOR characteristics measured in a group of age-matched healthy volunteers who were subjected to horizontal whole body rotations with equivalent sinusoidal velocity profiles at the same frequencies. A strong and significant effect of frequency was observed in the total peak eye velocity of the eVOR. This effect was similar to that observed in the "natural" VOR. Other characteristics of the (e)VOR (angle, habituation-index, and asymmetry) showed no significant frequency-dependent effect. In conclusion, this study demonstrates that, at least at the specific (limited) frequency range tested, responses elicited by a vestibular implant closely mimic the frequency-dependency of the "normal" vestibular system.

  8. Optical and Electrical Properties of Single-walled Carbon Nanotubes with Known Chiralities

    Science.gov (United States)

    Zhang, Zhengyi

    Carbon nanotube (CNT) is a hollow structure consisted by one-atom-thick sheet of carbon atoms, which can be considered as a rolled-up graphene sheet. The diameter and rolling angle (chirality) uniquely determines its electronic structure. Over two decades of study, due to the difficulty of synthesizing clean individual CNTs and the limitation of accurate chirality characterization, there are still unveiled questions towards the intrinsic properties of this 1-D material at single molecular level. In this thesis, I will discuss the approaches of fabricating chirality assigned CNT device and the experimental results of its optical and electrical properties. In the first part, I describe using 'fast heating' chemical vapor deposition (CVD) method to achieve the high quality suspended CNT growth. Combining Rayleigh and Raman spectroscopy, I demonstrate the accurate assignment of chirality for each suspended individual CNT. With the ability of chirality identification, a series of optical and electrical experiments were conducted on the selected CNTs of interest. In the following part, I first discuss the probe of many-body effect in a semiconducting CNT by observing the elastic scattering (Rayleigh spectra) with electrostatic gating. We found the dominant short-range interaction is reduced to 85% of its intrinsic strength for doping level of rho=0.4e/nm, demonstrating the possible control of sub-band exciton resonance frequency without rely on Pauli-blocking effect in CNTs. In order to study the substrate effect in electrical transport of CNTs, I improved the transfer technique to accurately place individual CNT on a specific substrate. With this technique, I've achieved transferring individual CNT on 20mum thin layer of hexagonal-boron nitride (h-BN) substrate with a +/- 5mum error. The low field electrical transport studies were conducted on both metallic and semiconducting CNTs with known chiralities on h-BN. Temperature dependent measurement shows the resistivity

  9. Mechanical properties of fibroblasts depend on level of cancer transformation.

    Science.gov (United States)

    Efremov, Yu M; Lomakina, M E; Bagrov, D V; Makhnovskiy, P I; Alexandrova, A Y; Kirpichnikov, M P; Shaitan, K V

    2014-05-01

    Recently, it was revealed that tumor cells are significantly softer than normal cells. Although this phenomenon is well known, it is connected with many questions which are still unanswered. Among these questions are the molecular mechanisms which cause the change in stiffness and the correlation between cell mechanical properties and their metastatic potential. We studied mechanical properties of cells with different levels of cancer transformation. Transformed cells in three systems with different transformation types (monooncogenic N-RAS, viral and cells of tumor origin) were characterized according to their morphology, actin cytoskeleton and focal adhesion organization. Transformation led to reduction of cell spreading and thus decreasing the cell area, disorganization of actin cytoskeleton, lack of actin stress fibers and decline in the number and size of focal adhesions. These alterations manifested in a varying degree depending on type of transformation. Force spectroscopy by atomic force microscopy with spherical probes was carried out to measure the Young's modulus of cells. In all cases the Young's moduli were fitted well by log-normal distribution. All the transformed cell lines were found to be 40-80% softer than the corresponding normal ones. For the cell system with a low level of transformation the difference in stiffness was less pronounced than for the two other systems. This suggests that cell mechanical properties change upon transformation, and acquisition of invasive capabilities is accompanied by significant softening.

  10. Surface-Controlled Properties of Myosin Studied by Electric Field Modulation.

    Science.gov (United States)

    van Zalinge, Harm; Ramsey, Laurence C; Aveyard, Jenny; Persson, Malin; Mansson, Alf; Nicolau, Dan V

    2015-08-04

    The efficiency of dynamic nanodevices using surface-immobilized protein molecular motors, which have been proposed for diagnostics, drug discovery, and biocomputation, critically depends on the ability to precisely control the motion of motor-propelled, individual cytoskeletal filaments transporting cargo to designated locations. The efficiency of these devices also critically depends on the proper function of the propelling motors, which is controlled by their interaction with the surfaces they are immobilized on. Here we use a microfluidic device to study how the motion of the motile elements, i.e., actin filaments propelled by heavy mero-myosin (HMM) motor fragments immobilized on various surfaces, is altered by the application of electrical loads generated by an external electric field with strengths ranging from 0 to 8 kVm(-1). Because the motility is intimately linked to the function of surface-immobilized motors, the study also showed how the adsorption properties of HMM on various surfaces, such as nitrocellulose (NC), trimethylclorosilane (TMCS), poly(methyl methacrylate) (PMMA), poly(tert-butyl methacrylate) (PtBMA), and poly(butyl methacrylate) (PBMA), can be characterized using an external field. It was found that at an electric field of 5 kVm(-1) the force exerted on the filaments is sufficient to overcome the frictionlike resistive force of the inactive motors. It was also found that the effect of assisting electric fields on the relative increase in the sliding velocity was markedly higher for the TMCS-derivatized surface than for all other polymer-based surfaces. An explanation of this behavior, based on the molecular rigidity of the TMCS-on-glass surfaces as opposed to the flexibility of the polymer-based ones, is considered. To this end, the proposed microfluidic device could be used to select appropriate surfaces for future lab-on-a-chip applications as illustrated here for the almost ideal TMCS surface. Furthermore, the proposed methodology can

  11. Preparation and study of thickness dependent electrical characteristics of zinc sulfide thin films

    Indian Academy of Sciences (India)

    A U Ubale; D K Kulkarni

    2005-02-01

    Zinc sulfide thin films have been deposited onto glass substrates by chemical bath deposition. The various deposition parameters such as volume of sulfide ion source, pH of bath, deposition time, temperature etc are optimized. Thin films of ZnS with different thicknesses of 76–332 nm were prepared by changing the deposition time from 6–20 h at 30°C temperature. The effect of film thickness on structural and electrical properties was studied. The electrical resistivity was decreased from 1.83 × 105 -cm to 0.363 × 105 -cm as film thickness decreased from 332 nm to 76 nm. The structural and activation energy studies support this decrease in the resistivity due to improvement in crystallinity of the films which would increase the charge carrier mobility and decrease in defect levels with increase in the thickness.

  12. Electrical and Electrochemical Properties of Nitrogen-Containing Tetrahedral Amorphous Carbon (ta-C) Thin Films

    Science.gov (United States)

    Yang, Xingyi

    Tetrahedral amorphous carbon (ta-C) is a diamond-like carbon (DLC) material comprised of a mixture of sp2 (˜40%) and sp3-bonded (˜60%) carbon domains. The physicochemical structure and electrochemical properties depend strongly on the sp2/sp3 bonding ratio as well as the incorporation of impurities, such as hydrogen or nitrogen. The ability to grow ta-C films at lower temperatures (25-100 °C) on a wider variety of substrates is a potential advantage of these materials as compared with diamond films. In this project, the basic structural and electrochemical properties of nitrogen-incorporated ta-C thin films will be discussed. The major goal of this work was to determine if the ta-C:N films exhibit electrochemical properties more closely aligned with those of boron-doped diamond (sp 3 carbon) or glassy carbon (amorphous sp2 carbon). Much like diamond, ta-C:N thin-film electrodes are characterized by a low background voltammetric current, a wide working potential window, relatively rapid electron-transfer kinetics for aqueous redox systems, such as Fe(CN) 6-3/-4 and Ru(NH3)6+3/+2 , and weak adsorption of polar molecules from solution. For example, negligible adsorption of methylene blue was found on the ta-C:N films in contrast to glassy carbon; a surface on which this molecule strongly adsorbs. The film microstructure was studied with x-ray photoelectron microscopy (XPS), visible Raman spectroscopy and electron-energy loss spectroscopy (EELS); all of which revealed the sp2-bonded carbon content increased with increasing nitrogen. The electrical properties of ta-C:N films were studied by four-point probe resistance measurement and conductive-probe AFM (CP-AFM). The incorporation of nitrogen into ta-C films increased the electrical conductivity primarily by increasing the sp2-bonded carbon content. CP-AFM showed the distribution of the conductive sp2-carbon on the film surface was not uniform. These films have potential to be used in field emission area. The

  13. An investigation of the electrical transport properties of graphene-oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Venugopal, Gunasekaran, E-mail: pvsguna@gmail.com [Nano Materials and System Lab, Department of Mechanical Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Faculty of Nanosciences and Technology Department, School of Nanosciences and Technology, Karunya University, Coimbatore 641 114, Tamil Nadu (India); Krishnamoorthy, Karthikeyan [Nano Materials and System Lab, Department of Mechanical Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Mohan, Rajneesh [Department of Mechatronics Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Kim, Sang-Jae, E-mail: kimsangj@jejunu.ac.kr [Nano Materials and System Lab, Department of Mechanical Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Faculty of Mechatronics Engineering and Research Institute of Advanced Technology, Jeju National University, Jeju 690-756 (Korea, Republic of)

    2012-01-16

    Highlights: Black-Right-Pointing-Pointer Four terminal electrical transport characterization of graphene-oxide thin film. Black-Right-Pointing-Pointer Low temperature R-T and I-V studies on GO thin film. Black-Right-Pointing-Pointer Electrical transport obeys VRH mechanism supported by Raman spectra. Black-Right-Pointing-Pointer GO characterizations by SEM, AFM, UV-vis, XRD, FTIR and XPS. Black-Right-Pointing-Pointer GO-FET confirms the p-type semiconducting behavior. - Abstract: The electrical transport properties of graphene-oxide (GO) thin films were investigated. The GO was synthesized by a modified Hummers method and was characterized by X-ray diffraction and UV-visible spectroscopy. The thin film of GO was made on a Si/SiO{sub 2} substrate by drop-casting. The surface morphology of the GO film was analyzed by using scanning electron microscopy and atomic force microscopy techniques. Temperature dependent resistance and current-voltage measurements were studied using four-terminal method at various temperatures (120, 150, 175, 200, 250 and 300 K) and their charge transport followed the 3D variable range hopping mechanism which was well supported by Raman spectra analysis. The presence of various functional groups in GO were identified by using high resolution X-ray photo electron (XPS) and Fourier transform infra red (FT-IR) spectroscopic techniques. Graphene-oxide thin film field effect transistor devices show p-type semiconducting behavior with a hole mobility of 0.25 cm{sup 2} V{sup -1} s{sup -1} and 0.59 cm{sup 2} V{sup -1} s{sup -1} when measured in air and vacuum respectively.

  14. Statistical Properties of Antenna Impedance in an Electrically Large Cavity

    Energy Technology Data Exchange (ETDEWEB)

    WARNE,LARRY K.; LEE,KELVIN S.H.; HUDSON,H. GERALD; JOHNSON,WILLIAM A.; JORGENSON,ROY E.; STRONACH,STEPHEN L.

    2000-12-13

    This paper presents models and measurements of antenna input impedance in resonant cavities at high frequencies.The behavior of input impedance is useful in determining the transmission and reception characteristics of an antenna (as well as the transmission characteristics of certain apertures). Results are presented for both the case where the cavity is undermoded (modes with separate and discrete spectra) as well as the over moded case (modes with overlapping spectra). A modal series is constructed and analyzed to determine the impedance statistical distribution. Both electrically small as well as electrically longer resonant and wall mounted antennas are analyzed. Measurements in a large mode stirred chamber cavity are compared with calculations. Finally a method based on power arguments is given, yielding simple formulas for the impedance distribution.

  15. Thermal and electrical properties of a solid through Fibonacci oscillators

    Science.gov (United States)

    Marinho, André A.; Brito, Francisco A.; Chesman, Carlos

    2016-02-01

    We investigate the thermodynamics of a crystalline solid applying q-deformed algebra of Fibonacci oscillators through the generalized Fibonacci sequence of two real and independent deformation parameters q1 and q2. We based part of our study on both Einstein and Debye models, exploring primarily (q1, q2) -deformed thermal and electric conductivities as a function of Debye specific heat. The results revealed that q-deformation acts as a factor of disorder or impurity, modifying the characteristics of a crystalline structure. Specially, one may find the possibility of adjusting the Fibonacci oscillators to describe the change of thermal and electrical conductivities of a given element as one inserts impurities. Each parameter can be associated to different types of deformations such as disorders and impurities.

  16. Electrical properties of the sensitive side in Si edgeless detectors

    CERN Document Server

    Verbitskaya, E; Eremin, I; Ilyashenko, I; Cavallini, A; Castaldini, A; Pellegrini, G; Lozano, M; Golubkov, S; Egorov, N; Konkov, K; Tuuva, T

    2009-01-01

    Silicon edgeless detectors represent a novel type of detector that are being developed for close-to-beam applications in high-energy physics and for large-scale tiled 1D and 2D arrays used in radiation imaging. In this work, the electric field and potential distributions on the device cut side, key factors in detector performance, have been investigated using two methods—the Conductive Microprobe Technique and the Scanning Transient Current Technique. It has been found that the behaviour of the potential distribution at the edge indicates a significant presence of positively charged states, with the charge density changing with the applied voltage. This work will predict, to a first approximation, the trend of the electric field at the edge of these devices after irradiation to high fluences. This prediction will provide key inputs in the development of edgeless radiation hard detectors.

  17. Electrical properties of nanostructured SiN films for MEMS capacitive switches

    Science.gov (United States)

    Koutsoureli, M.; Xavier, S.; Michalas, L.; Lioutas, C.; Bansropun, S.; Papaioannou, G.; Ziaei, A.

    2017-01-01

    The electrical properties of gold nanorods nanostructured silicon nitride films are comprehensively investigated with the aid of metal-insulator-metal capacitors and RF MEMS capacitive switches. Different nanorod diameters and densities were grown on the bottom electrode and with orientation normal to dielectric film surface. A simple physical model, which does not take the effect of electric field fringing into account, was developed to describe both the DC and low frequency electrical properties. It has been shown that the nanorods distribution and dimensions determine the electrical properties as well as the dielectric charging phenomena of the nanostructured films. Finally, in MEMS switches it has been shown that the nanorods presence does not affect the capacitance variance nor the RF characteristics of the device.

  18. The effect of CNTs reinforcement on thermal and electrical properties of cement-based materials

    Science.gov (United States)

    Exarchos, D. A.; Dalla, P. T.; Tragazikis, I. K.; Matikas, T. E.

    2015-03-01

    This research aims to investigate the influence of the nano-reinforcement on the thermal properties of cement mortar. Nano-modified cement mortar with carbon nanotubes (CNTs) leading to the development of innovative materials possessing multi-functionality and smartness. Such multifunctional properties include enhanced mechanical behavior, electrical and thermal conductivity, and piezo-electric characteristics. The assessment of the thermal behavior was evaluated using IR Thermography. Two different thermographic techniques are used to monitor the influence of the nano-reinforcement. To eliminate any extrinsic effects (e.g. humidity) the specimens were dried in an oven before testing. The electrical resistivity was measured with a contact test method using a custom made apparatus and applying a known D.C. voltage. This study indicate that the CNTs nano-reinforcement enhance the thermal and electrical properties and demonstrate them useful as sensors in a wide variety of applications.

  19. Defect and electrical properties of nanocrystalline tungsten trioxide

    Institute of Scientific and Technical Information of China (English)

    Yang Xin-Sheng; Wang Yu; Dong Liang; Qi Li-Zhen; Zhang Feng

    2004-01-01

    Nanocrystalline tungsten trioxide particles were prepared by a wet-chemical method. Transmission electron microscope (TEM) analysis shows that the average grain size is about 15nm. The oxygen deficiency of nanometre-sized sample is higher than that of ordinary tungsten trioxide. The electric conductivity increases because of high oxygen deficiency. Ironic relaxation polarization and crystallographic shear (CS) planes theory were used to explain the unusual dielectric characteristic of nanocrystalline tungsten trioxide.

  20. Voltage-dependent magnetic phase transition in magneto-electric epitaxial Cr2O3 nanoclusters

    Science.gov (United States)

    Halley, David; Najjari, Nabil; Godel, Florian; Hamieh, Mohamad; Doudin, Bernard; Henry, Yves

    2016-06-01

    We observe, as a function of temperature, a second order magnetic phase transition in nanometric Cr2O3 clusters that are epitaxially embedded in an insulating MgO matrix. They are investigated through their tunnel magneto-resistance signature, the MgO layer being used as a tunnel barrier. We infer the small magnetic dipoles carried by the Cr2O3 clusters and provide evidence of a magnetic phase transition at low temperature in those clusters: they evolve from an anti ferromagnetic state, with zero net moment close to 0 K, to a weak ferromagnetic state that saturates above about 10 K. The influence of magneto-electric effects on the weak ferromagnetic phase is also striking: the second order transition temperature turns out to be linearly dependent on the applied electric field.

  1. Impedance spectroscopy analysis on electrical properties of serpentine at high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    朱茂旭; 谢鸿森; 郭捷; 许祖鸣; 白武明

    2001-01-01

    The electrical conductivity of serpentine is measured and the microscopic conductance mechanisms are investigated with impedance spectroscopy at 2.5-4.0 GPa and 220-780℃. The results show that the electrical conductivity is strongly dependent on the frequencies used, and that only arcⅠ, which reflects grain interior conductance, occurs and dominates the whole conductance processes over 12-105 Hz at high pressure before dehydration. The arcⅡ, which indicates the grain boundary process, begins to occur at the initial stage of dehydration. After dehydration, due to the presence of highly conductive networks of free water, the electrical conductivity is not depen-dent on frequencies any longer and the total electrical conductivity is dominated by process of ionic conductance of free water in interconnected networks. Dehydration of serpentine enhances pro-nouncedly the total electrical conductivity, through which highly conductive layers (HCL) may be formed in the earth's interior.

  2. Electrical resistivity and dielectric properties of helical microorganism cells coated with silver by electroless plating

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Jun, E-mail: jun_cai@buaa.edu.cn [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Lan, Mingming; Zhang, Deyuan; Zhang, Wenqiang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer We use the microorganism cells as forming templates to fabricate the bio-based conductive particles. Black-Right-Pointing-Pointer The microorganism cells selected as forming templates are Spirulina platens, which are of natural helical shape and high aspect ratio. Black-Right-Pointing-Pointer The sliver-coated Spirulina cells are a kind of lightweight conductive particles. Black-Right-Pointing-Pointer The composites containing sliver-coated Spirulina cells exhibit a lower percolation value. - Abstract: In this paper, microorganism cells (Spirulina platens) were used as forming templates for the fabrication of the helical functional particles by electroless silver plating process. The morphologies and ingredients of the coated Spirulina cells were analyzed with scanning electron microscopy and energy dispersive spectrometer. The crystal structures were characterized by employing the X-ray diffraction. The electrical resistivity and dielectric properties of samples containing different volume faction of sliver-coated Spirulina cells were measured and investigated by four-probe meter and vector network analyzer. The results showed that the Spirulina cells were successfully coated with a uniform silver coating and their initial helical shapes were perfectly kept. The electrical resistivity and dielectric properties of the samples had a strong dependence on the volume content of sliver-coated Spirulina cells and the samples could achieve a low percolation value owing to high aspect ratio and preferable helical shape of Spirulina cells. Furthermore, the conductive mechanism was analyzed with the classic percolation theory, and the values of {phi}{sub c} and t were obtained.

  3. Characteristics of frictional properties' dependency on afterslip propagation speed

    Science.gov (United States)

    Ariyoshi, K.; Matsuzawa, T.; Hasegawa, A.; Hino, R.; Hori, T.

    2016-12-01

    The propagation speed of postseismic slip seems to vary from place to place. On the 2003 Tokachi-Oki earthquake (M8), the time lag is about 80 minutes for the largest aftershock (M7.4) off Tokachi [Miyazaki and Larson, 2008 GRL] and one year for the M7 earthquakes off Kushiro [Murakami et al., 2006 GRL]. Since the distance from the epicenter of mainshock to the largest aftershock and the M7 aftershocks off Kushiro is about 40 km and 160 km, respectively, these time lags means that propagation speed of the afterslip from the mainshock to the largest aftershock is significantly higher than to the M7 afteshocks off Kushiro. On the Sanriku-Haruka-Oki earthquakes, Matsuzawa et al. [2004 EPS] pointed out that propagation speed of the postseismic slip seems to be an order of 10 km/day for shallower part of the subduction plate boundary while 10 km/month for deeper part. These results indicate that propagation speed of postseismic slip depends on frictional properties and effective normal stress in addition to slip velocity. To know the frictional properties controlling the propagation speed of postseismic slip, some numerical simulations of interplate earthquakes based on a rate- and state-dependent friction law (RSF) [Dieterich, 1979 JGR; Ruina, 1983 JGR] have been recently performed. From those previous studies, the propagation speed of postseismic slip becomes lower in case of higher frictional stability, longer characteristic slip distance [Kato and Hirasawa, 1999 PAGEOPH], and higher effective normal stress [Ariyoshi et al., 2007 EPSL]. Since we have not quantitatively understood why such cases make the postseismic slip propagation slower, it is necessary to know analytical relation between the frictional properties and the propagation speed of postseismic slip. In this study, we develop an expression for the propagation speed of postseismic slip as a function of frictional properties including effective normal stress, and discuss its validity quantitatively by

  4. Some investigations on thickness-dependent electrical behaviour of CdS:As/electrolyte solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, L.P. (Dept. of Applied Electronics, Shivaji Univ., Solapur (India)); Hankare, P.P. (Dept. of Polymer Chemistry, Shivaji Univ., Solapur (India)); Sawant, V.S. (Dept. of Electronics, Y.C. Inst. of Science, Satara (India))

    1991-12-01

    An investigation has been made into the effect of photoelectrode thickness of the photovoltaic properties of cadmium sulphide/electrolyte solar cells. CdS photoelectrodes of various thicknesses doped with 0.25wt.% arsenic were prepared by a chemical deposition process on plane mirror smooth stainless steel substrates. An electrode/electrolyte junction cell was designed for use in a glass cuvette and has been analysed in terms of its electrical parameters. The thickness of the photoelectrode was found to cause significant changes in cell parameters such as short-circuit current, open-circuit voltage, series and shunt resistances, fill factor, junction quality factors and flat band potential. (orig.).

  5. Structural, magnetic and electrical properties of Zr-substitued NiZnCo ferrite nanopowders

    Science.gov (United States)

    Li, Le-Zhong; Zhong, Xiao-Xi; Wang, Rui; Tu, Xiao-Qiang

    2017-08-01

    Zr-substituted NiZnCo ferrite nanopowders, Ni0.4-xZn0.5ZrxCo0.1Fe2.0O4 (0 ≤ x ≤ 0.20), were synthesized by the sol-gel auto-combustion method. The effects of Zr substitution on the structural, magnetic and electrical properties have been investigated. The DTA and TG results indicate that there are three steps of combustion process. The X-ray diffraction patterns show that the lattice parameter and the average crystallite size increase with the increase of Zr substitution. The saturation magnetization increases with the increase of Zr substitution when x ≤ 0.05, and then decreases when x > 0.05. Meanwhile, the coercivity initially decreases with the increase of Zr substitution when x ≤ 0.05, and then increases when x > 0.05. The polarization behavior for all the samples in the test frequency range from100 Hz to10 MHz obeys the charge polarization mechanism, which happens since the frequency of the hopping of electron exchange between Fe2+ and Fe3+ ions are far from the frequency of alternating-current field. And the dielectric constant increases with the increase of Zr substitution. The relaxation peak of the frequency dependence of dielectric loss is observed for x ≥ 0.10, which is due to the frequency of charge hopping between the Fe2+ and Fe3+ exactly matches with the frequency of the external applied field. Electrical transport behavior of the ferrite nanopowders is found to follow the impurity semiconductor, and the effect of Zr substitution on the temperature dependence of dc resistivity is observed.

  6. A Phenomenological Model of the Electrically Stimulated Auditory Nerve Fiber: Temporal and Biphasic Response Properties.

    Science.gov (United States)

    Horne, Colin D F; Sumner, Christian J; Seeber, Bernhard U

    2016-01-01

    We present a phenomenological model of electrically stimulated auditory nerve fibers (ANFs). The model reproduces the probabilistic and temporal properties of the ANF response to both monophasic and biphasic stimuli, in isolation. The main contribution of the model lies in its ability to reproduce statistics of the ANF response (mean latency, jitter, and firing probability) under both monophasic and cathodic-anodic biphasic stimulation, without changing the model's parameters. The response statistics of the model depend on stimulus level and duration of the stimulating pulse, reproducing trends observed in the ANF. In the case of biphasic stimulation, the model reproduces the effects of pseudomonophasic pulse shapes and also the dependence on the interphase gap (IPG) of the stimulus pulse, an effect that is quantitatively reproduced. The model is fitted to ANF data using a procedure that uniquely determines each model parameter. It is thus possible to rapidly parameterize a large population of neurons to reproduce a given set of response statistic distributions. Our work extends the stochastic leaky integrate and fire (SLIF) neuron, a well-studied phenomenological model of the electrically stimulated neuron. We extend the SLIF neuron so as to produce a realistic latency distribution by delaying the moment of spiking. During this delay, spiking may be abolished by anodic current. By this means, the probability of the model neuron responding to a stimulus is reduced when a trailing phase of opposite polarity is introduced. By introducing a minimum wait period that must elapse before a spike may be emitted, the model is able to reproduce the differences in the threshold level observed in the ANF for monophasic and biphasic stimuli. Thus, the ANF response to a large variety of pulse shapes are reproduced correctly by this model.

  7. Optical and electrical properties of glycine manganese chloride crystal

    Science.gov (United States)

    Venkatesan, G.; Kathiravan, V.; Pari, S.

    2017-06-01

    The organo-metal material of Glycine Manganese Chloride has been grown by solvent evaporation solution growth method. Single crystal XRD study has been carried out to confirm the grown crystal. FT-IR was recorded to identify the functional groups present in the crystal. The linear optical property of the grown crystal was analyzed by UV-Vis spectrum. Third order nonlinear optical properties was measured by Z-scan technique using Nd:YAG laser at 532 nm. Fluorescence emission revealed that can serve as a photo active material. Impedance and dielectric studies were also carried out for the material. Thermal property of the sample was analyzed by TG and DTA studies. The predicted NLO properties, UV-Vis absorbance and Z-scan studies indicate that the attractive material for optical applications.

  8. Properties of precise firing synchrony between synaptically coupled cortical interneurons depend on their mode of coupling.

    Science.gov (United States)

    Hu, Hang; Agmon, Ariel

    2015-07-01

    Precise spike synchrony has been widely reported in the central nervous system, but its functional role in encoding, processing, and transmitting information is yet unresolved. Of particular interest is firing synchrony between inhibitory cortical interneurons, thought to drive various cortical rhythms such as gamma oscillations, the hallmark of cognitive states. Precise synchrony can arise between two interneurons connected electrically, through gap junctions, chemically, through fast inhibitory synapses, or dually, through both types of connections, but the properties of synchrony generated by these different modes of connectivity have never been compared in the same data set. In the present study we recorded in vitro from 152 homotypic pairs of two major subtypes of mouse neocortical interneurons: parvalbumin-containing, fast-spiking (FS) interneurons and somatostatin-containing (SOM) interneurons. We tested firing synchrony when the two neurons were driven to fire by long, depolarizing current steps and used a novel synchrony index to quantify the strength of synchrony, its temporal precision, and its dependence on firing rate. We found that SOM-SOM synchrony, driven solely by electrical coupling, was less precise than FS-FS synchrony, driven by inhibitory or dual coupling. Unlike SOM-SOM synchrony, FS-FS synchrony was strongly firing rate dependent and was not evident at the prototypical 40-Hz gamma frequency. Computer simulations reproduced these differences in synchrony without assuming any differences in intrinsic properties, suggesting that the mode of coupling is more important than the interneuron subtype. Our results provide novel insights into the mechanisms and properties of interneuron synchrony and point out important caveats in current models of cortical oscillations.

  9. Direct method for calculating temperature-dependent transport properties

    Science.gov (United States)

    Liu, Yi; Yuan, Zhe; Wesselink, R. J. H.; Starikov, Anton A.; van Schilfgaarde, Mark; Kelly, Paul J.

    2015-06-01

    We show how temperature-induced disorder can be combined in a direct way with first-principles scattering theory to study diffusive transport in real materials. Excellent (good) agreement with experiment is found for the resistivity of Cu, Pd, Pt (and Fe) when lattice (and spin) disorder are calculated from first principles. For Fe, the agreement with experiment is limited by how well the magnetization (of itinerant ferromagnets) can be calculated as a function of temperature. By introducing a simple Debye-like model of spin disorder parameterized to reproduce the experimental magnetization, the temperature dependence of the average resistivity, the anisotropic magnetoresistance, and the spin polarization of a Ni80Fe20 alloy are calculated and found to be in good agreement with existing data. Extension of the method to complex, inhomogeneous materials as well as to the calculation of other finite-temperature physical properties within the adiabatic approximation is straightforward.

  10. Electric field gradient and electronic properties of crown thioether compounds

    Energy Technology Data Exchange (ETDEWEB)

    Camargo Dalmatti Alves Lima, Filipe, E-mail: flima@if.usp.br; Rodrigues do Nascimento, Rafael; Brown Goncalves, Marcos [Universidade de Sao Paulo, Instituto de Fisica (Brazil); Cottenier, Stefaan [Ghent University, Center for Molecular Modeling (Belgium); Caldas, Marilia Junqueira; Petrilli, Helena Maria [Universidade de Sao Paulo, Instituto de Fisica (Brazil)

    2010-04-15

    We compare published TDPAC experiments on {sup 111}Cd in the crown thioether C{sub 6}H{sub 12}S{sub 3}AgCl with ab-initio electronic structure calculations performed within the framework of the Density Functional Theory using the Projector Augmented Wave method. We conclude from this comparison that the Cd atom at the very moment of the TDPAC experiment is positively charged, and we point out to a methodological difference between reproducing experimental electric-field gradients in molecules versus solid metals.

  11. Electrical properties of spherical dipole antennas with lossy material cores

    DEFF Research Database (Denmark)

    Hansen, Troels Vejle; Kim, Oleksiy S.; Breinbjerg, Olav

    2012-01-01

    A spherical magnetic dipole antenna with a linear, isotropic, homogenous, passive, and lossy material core is modeled analytically, and closed form expressions are given for the internally stored magnetic and electric energies, the radiation efficiency, and radiation quality factor. This model...... size and permittivity, focusing on the effects of magnetic core losses for a simple magnetic dispersion model, to illustrate how stored energies, efficiency and quality factor are affected. This shows that large magnetic losses can be beneficial, as these can produce a relatively high efficiency....

  12. Isospin properties of electric dipole excitations in 48 Ca

    OpenAIRE

    Derya, V.; Savran, D.; Endres, J.; Harakeh, M. N; Hergert, H.; Kelley, J.H.; Papakonstantinou, P.; Pietralla, N.; Ponomarev, V. Yu.; Roth, R.; Rusev, G.; Tonchev, A. P.; Tornow, W; Wörtche, H. J.; Zilges, A.

    2014-01-01

    Two different experimental approaches were combined to study the electric dipole strength in the doubly-magic nucleus 48 Ca below the neutron threshold. Real-photon scattering experiments using bremsstrahlung up to 9.9 MeV and nearly mono-energetic linearly polarized photons with energies between 6.6 and 9.51 MeV provided strength distribution and parities, and an (α,α′γ) experiment at Eα=136MeV gave cross sections for an isoscalar probe. The unexpected difference observed in the dipole respo...

  13. Laboratory device to analyse the impact of soil properties on electrical and thermal conductivity

    Science.gov (United States)

    Bertermann, David; Schwarz, Hans

    2017-04-01

    Gathering information about soil properties in an efficient way is essential for many soil applications also for very shallow geothermal systems (e.g. collector systems or heat baskets). In the field, electrical resistivity tomogramphy measurements enable non-invasive and extensive analyses regarding the determination of soil properties. For a better understanding of measured electrical resistivity values in relation to soil properties within this study, a laboratory setup was developed. The structure of this laboratory setup is geared to gather electrical resistivity or rather electrical conductivity values which are directly comparable to data measured in the field. Within this setup grain size distribution, moisture content, and bulk density, which are the most important soil parameters affecting the electrical resistivity, can be adjusted. In terms of a better estimation of the geothermal capability of soil, thermal conductivity measurements were also implemented within the laboratory test sequence. The generated data reveals the serious influence of the water content and also provides a huge impact of the bulk density on the electrical as well as on the thermal conductivity. Furthermore, different behaviour patterns of electrical and thermal conductivity in their particular relation to the different soil parameters could be identified.

  14. Assessing the Firing Properties of the Electrically Stimulated Auditory Nerve Using a Convolution Model.

    Science.gov (United States)

    Strahl, Stefan B; Ramekers, Dyan; Nagelkerke, Marjolijn M B; Schwarz, Konrad E; Spitzer, Philipp; Klis, Sjaak F L; Grolman, Wilko; Versnel, Huib

    2016-01-01

    The electrically evoked compound action potential (eCAP) is a routinely performed measure of the auditory nerve in cochlear implant users. Using a convolution model of the eCAP, additional information about the neural firing properties can be obtained, which may provide relevant information about the health of the auditory nerve. In this study, guinea pigs with various degrees of nerve degeneration were used to directly relate firing properties to nerve histology. The same convolution model was applied on human eCAPs to examine similarities and ultimately to examine its clinical applicability. For most eCAPs, the estimated nerve firing probability was bimodal and could be parameterised by two Gaussian distributions with an average latency difference of 0.4 ms. The ratio of the scaling factors of the late and early component increased with neural degeneration in the guinea pig. This ratio decreased with stimulation intensity in humans. The latency of the early component decreased with neural degeneration in the guinea pig. Indirectly, this was observed in humans as well, assuming that the cochlear base exhibits more neural degeneration than the apex. Differences between guinea pigs and humans were observed, among other parameters, in the width of the early component: very robust in guinea pig, and dependent on stimulation intensity and cochlear region in humans. We conclude that the deconvolution of the eCAP is a valuable addition to existing analyses, in particular as it reveals two separate firing components in the auditory nerve.

  15. Synthesis, investigation on structural and electrical properties of cobalt doped Mn–Zn ferrite nanocrystalline powders

    Directory of Open Access Journals (Sweden)

    Bhuvaneswari M.

    2016-06-01

    Full Text Available Synthesis of CoxMnyZnyFe2O4 (x = 0.1, 0.5, 0.9 and y = 0.45, 0.25, 0.05 nanocrystalline powders was done by chemical co-precipitation method. The crystal structure was determined by using X-ray diffraction (XRD studies. The crystallite size and lattice parameters were calculated from the XRD data. The XRD results revealed that the crystallite size of the nanocrystalline powder was found to decrease from 37 nm to 28 nm with the substitution of cobalt. The effect of cobalt ions on the crystallization process, the lattice parameters and electrical properties of Mn–Zn ferrites has been also investigated. The AC conductivity increased with an increase in frequency but it decreased with an increase in cobalt content. The complex impedance analysis of the data showed that the resistive and capacitive properties of the Co–Mn–Zn ferrite are predominant due to the fact that the processes are associated with the grains and grain boundaries. The dielectric constant and dielectric loss dependence on doping level and frequency at room temperature were also studied.

  16. Thermal, mechanical and electrical properties of polyanaline based ceramic nano-composites

    Science.gov (United States)

    Sohail, M.; Khan, M. S.; Khattak, N. S.

    2016-08-01

    Micro/nanohybrid materials have vast applications due to their great potentialities in the field of nanoscience and nanotechnology. Herein we report an investigation on the fabrication and physicochemical characterization of ceramic (Fe0.01La0.01Al0.5Zn0.98O) and hybrid ceramic-polyaniline nano-composits. Ceramic nano-particles were prepared by sol-gel technique while optimizing the molar ratios of the constituent's metal nitrates. The prepared inorganic particles were then embedded in the polymer matrix via one-pot blending method. The prepared ceramic particles and their composites with polyaniline were analysed under FT- IR, SEM and TGA. The presence of some chemical species was observed at the interface of the compositing materials. TGA analysis showed the thermal stability of the composite material. Frequency dependent dielectric properties were analysed and it was found that conducting polyaniline has an additional effect on the electrical behaviour of the composite. Rheology study showed enhanced mechanical properties of composite material as compared to their constituting counterparts.

  17. Electrical and Structural Properties of Ni-60%Cr Thin Film in an Embedded Resistor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Yoo; Son, Hwa-Jin; Lim, Seung-Kyu; Lee, Kwang-Keun; Suh, Su-Jeong [Sungkyunkwan University, Suwon (Korea, Republic of)

    2014-02-15

    The NiCr alloy has relatively large resistivity, good resistant to oxidation and low temperature coefficients of resistance (TCR) compared to other resistor metarials. These properties of NiCr thin films are dependent on the processing conditions including the deposition environment and subsequent annealing treatments. To establish optimizing conditions, Ni-60%Cr thin films were deposited by a sputtering method to control the resistivity and TCR. The experiments were carried out under various process pressures to determine the optimum conditions to achieve a high resistivity and low TCR. The thermal stability of Ni-60%Cr thin films at various heat treatment temperatures was also evaluated. The electrical properties of the sputtered Ni-60%Cr thin films were investigated by probe station and their crystal structures were observed by X-Ray Diffraction (XRD). The surface morphology was observed by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). As a result, a stable resistivity and TCR was respectively observed at 3-15 mTorr and 3-7 mTorr. The heat treatment results revealed an increase in thermal resistance with increasing temperature with a concomitant decrease in the TCR, and a near-zero TCR was obtained at 673 K.

  18. Particle self-bunching in the Schwinger effect in spacetime-dependent electric fields.

    Science.gov (United States)

    Hebenstreit, F; Alkofer, R; Gies, H

    2011-10-28

    Nonperturbative electron-positron pair creation (the Schwinger effect) is studied based on the Dirac-Heisenberg-Wigner formalism in 1+1 dimensions. An ab initio calculation of the Schwinger effect in the presence of a simple space- and time-dependent electric field pulse is performed for the first time, allowing for the calculation of the time evolution of observable quantities such as the charge density, the particle number density or the total number of created particles. We predict a new self-bunching effect of charges in phase space due to the spatial and temporal structure of the pulse.

  19. Magnetic and Electrical Properties of Sandwich-Like Lanthanide Phthalocyanines

    Science.gov (United States)

    1989-05-08

    dependance of extrinsic conduction. The greater the percentage of iodine, the wider the temperature- interval. The conductivity does not change very...Pc) 2 8.0 - 4 Er(Pc) 2Ix 11.0 -8.8 Lu(Pc)2 1.7 - Lu(Pc) 2IX 1.0 The temperature dependance - of the magnetic susceptibility follow the Curie-Weiss

  20. Size-dependent magnetic properties of branchlike nickel oxide nanocrystals

    Science.gov (United States)

    Liu, Dan; Li, Dongsheng; Yang, Deren

    2017-01-01

    Branchlike nickel oxide nanocrystals with narrow size distribution are obtained by a solution growth method. The size-dependent of magnetic properties of the nickel oxides were investigated. The results of magnetic characterization indicate that the NiO nanocrystals with size below 12.8 nm show very weak ferromagnetic state at room temperature due to the uncompensated spins. Both of the average blocking temperature (Tb) and the irreversible temperature (Tirr) increase with the increase of nanoparticle sizes, while both the remnant magnetization and the coercivity at 300 K increase with the decrease of the particle sizes. Moreover, the disappearance of two-magnon (2M) band and redshift of one-phonon longitudinal (1LO) and two-phonon LO in vibrational properties due to size reduction are observed. Compared to the one with the spherical morphological, it is also found that nano-structured nickel oxides with the branchlike morphology have larger remnant magnetization and the coercivity at 5 K due to their larger surface-to-volume ratio and greater degree of broken symmetry at the surface or the higher proportion of broken bonds.