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Showing papers on "Conductivity published in 2006"


Journal ArticleDOI
TL;DR: In this article, the static polarization function is calculated in two-dimensional graphite and used for the calculation of the conductivity limited by charged-impurity scattering, and the mobility remains independent of the Fermi energy.
Abstract: The static polarization function is calculated in two-dimensional graphite and used for the calculation of the conductivity limited by charged-impurity scattering. The conductivity increases in proportion to the electron concentration and the mobility remains independent of the Fermi energy, in qualitative agreement with experiments. The screening increases in proportion to temperature at sufficiently high temperatures in contrast to the behavior in conventional two-dimensional systems, leading to the mobility increase proportional to the square of temperature.

716 citations


Journal ArticleDOI
TL;DR: In this article, acceptor-doped rare earth ortho-niobates and ortho tantalates, RE1−xAxMO4 (M=Nb,Ta) were investigated and shown to have mixed protonic, native ionic and electronic conduction depending on conditions.
Abstract: Some oxides contain sufficient equilibrium concentrations of protons in wet atmospheres to show useful proton conduction at elevated temperatures1. As an example, Y-doped BaCeO3 has shown promising performance as a thin-film electrolyte in fuel cells at intermediate temperatures (400–600 ∘C)2. In contrast to proton-conducting polymers (for example, Nafion(R)) and acid salts (for example, CsHSO4), such oxidic ceramics are stable at sufficiently elevated temperatures that electrode kinetics are fast and insensitive to poisoning, but they tend to be basic (Ba-based or Sr-based) compounds with poor chemical and mechanical stability3. In search of more stable proton-conducting materials, we have investigated several acceptor-doped rare-earth ortho-niobates and ortho-tantalates, RE1−xAxMO4 (M=Nb,Ta). We show that this class of materials shows mixed protonic, native ionic and electronic conduction depending on conditions. Both the low-temperature monoclinic and high-temperature tetragonal polymorphs show proton conduction. The proton conductivity is dominant in wet atmospheres below roughly 800∘C and the highest proton conductivity of approximately 10−3Scm−1 was found for Ca-doped LaNbO4. These transport characteristics can be used in sensors and fuel cells provided that the electrolyte film thickness is in the micrometre range.

441 citations


Journal ArticleDOI
TL;DR: A novel method is presented whereby the parameters quantifying the conductivity of an ionomer can be extracted from the phenomenon of electrode polarization in the dielectric loss and tan delta planes.
Abstract: A novel method is presented whereby the parameters quantifying the conductivity of an ionomer can be extracted from the phenomenon of electrodepolarization in the dielectric loss and tan δ planes. Mobile ion concentrations and ion mobilities were determined for a poly(ethylene oxide)-based sulfonated ionomer with Li + , Na + , and Cs + cations. The validity of the model was confirmed by examining the effects of sample thickness and temperature. The Vogel-Fulcher-Tammann (VFT)-type temperature dependence of conductivity was found to arise from the Arrhenius dependence of ion concentration and VFT behavior of mobility. The ion concentration activation energy was found to be 25.2, 23.4, and 22.3 ± 0.5 kJ ∕ mol for ionomers containing Li + , Na + , and Cs + , respectively. The theoretical binding energies were also calculated and found to be ∼ 5 kJ ∕ mol larger than the experimental activation energies, due to stabilization by coordination with polyethylene glycol segments. Surprisingly, the fraction of mobile ions was found to be very small, < 0.004 % of the cations in the Li + ionomer at 20 ° C .

401 citations


Journal ArticleDOI
TL;DR: In this article, the direct relationship between the electronic conductivity of the nanostructured spinel LiMn2-xNixO4 and its lattice parameter is reported.
Abstract: The direct relationship between the electronic conductivity of the nanostructured spinel LiMn2-xNixO4 and its lattice parameter is reported. Within the 8.167−8.183 A range studied, there was a systematic 2.5 orders of magnitude difference between the highest electronic conductivity (cation disordered Fd3m spinel) to lowest conductivity (ordered P4332 spinel). The underlying reason behind the higher conductivity of the former was the presence of Mn3+ (nonexistent in ordered) and Mn4+ sites. The impact of the observed electronic conductivity on electrochemical performance is discussed with respect to morphological impact on ion diffusion and power delivery in various electrode formulations.

378 citations


Journal ArticleDOI
TL;DR: In this article, the electron transport properties of a monoatomic graphite layer (graphene) with different types of disorder were studied and it was shown that the transport properties depend strongly on the character of disorder.
Abstract: We study the electron transport properties of a monoatomic graphite layer (graphene) with different types of disorder. We show that the transport properties of the system depend strongly on the character of disorder. Away from half filling, the concentration dependence of conductivity is linear in the case of strong scatterers, in line with recent experimental observations, and logarithmic for weak scatterers. At half filling the conductivity is of the order of ${e}^{2}∕h$ if the randomness preserves one of the chiral symmetries of the clean Hamiltonian, whereas for generic disorder the conductivity is strongly affected by localization effects.

355 citations


Journal ArticleDOI
TL;DR: In this article, the water and acid swelling, mechanical strength, gas permeability and proton conductivity were studied for pristine and acid doped polybenzimidazole (PBI) membranes.

333 citations


Journal ArticleDOI
26 Oct 2006-Nature
TL;DR: In this paper, the electrical conductivity of synthetic polycrystalline olivine was determined from a.c. impedance measurements at a pressure of 4 GPa for a temperature range of 873-1,273 K for water contents of 0.01-0.08 wt%.
Abstract: It is well known that water (as a source of hydrogen) affects the physical and chemical properties of minerals--for example, plastic deformation and melting temperature--and accordingly plays an important role in the dynamics and geochemical evolution of the Earth. Estimating the water content of the Earth's mantle by direct sampling provides only a limited data set from shallow regions (<200 km depth). Geophysical observations such as electrical conductivity are considered to be sensitive to water content, but there has been no experimental study to determine the effect of water on the electrical conductivity of olivine, the most abundant mineral in the Earth's mantle. Here we report a laboratory study of the dependence of the electrical conductivity of olivine aggregates on water content at high temperature and pressure. The electrical conductivity of synthetic polycrystalline olivine was determined from a.c. impedance measurements at a pressure of 4 GPa for a temperature range of 873-1,273 K for water contents of 0.01-0.08 wt%. The results show that the electrical conductivity is strongly dependent on water content but depends only modestly on temperature. The water content dependence of conductivity is best explained by a model in which electrical conduction is due to the motion of free protons. A comparison of the laboratory data with geophysical observations suggests that the typical oceanic asthenosphere contains approximately 10(-2) wt% water, whereas the water content in the continental upper mantle is less than approximately 10(-3) wt%.

329 citations


Journal ArticleDOI
TL;DR: The thermal conductivity of thin films of the phase-change material Ge2Sb2Te5 is measured in the temperature range of 27°C
Abstract: The thermal conductivity of thin films of the phase-change material Ge2Sb2Te5 is measured in the temperature range of 27°C

299 citations


Journal ArticleDOI
26 Oct 2006-Nature
TL;DR: The data indicate that the hydration of olivine cannot account for the geophysical observations, which instead may be explained by the presence of partial melt elongated in the direction of plate motion.
Abstract: The oceanic asthenosphere is observed to have high electrical conductivity, which is highly anisotropic in some locations. In the directions parallel and normal to the plate motion, the conductivity is of the order of 10(-1) and 10(-2) S m(-1), respectively, which cannot be explained by the conductivity of anhydrous olivine. But because hydrogen can be incorporated in olivine at mantle pressures, this observation has been attributed to olivine hydration, which might cause anisotropically high conductivity by proton migration. To examine this hypothesis, here we report the effect of water on electrical conductivity and its anisotropy for hydrogen-doped and undoped olivine at 500-1,500 K and 3 GPa. The hydrous olivine has much higher conductivity and lower activation energy than anhydrous olivine in the investigated temperature range. Nevertheless, extrapolation of the experimental results suggests that conductivity of hydrous olivine at the top of the asthenosphere should be nearly isotropic and only of the order of 10(-2) S m(-1). Our data indicate that the hydration of olivine cannot account for the geophysical observations, which instead may be explained by the presence of partial melt elongated in the direction of plate motion.

271 citations


Journal ArticleDOI
TL;DR: In this article, a conductivity analysis of polypyrrole/yttrium oxide (PPy/Y2O3) composites was performed by in situ polymerization of pyrrole with Y 2O3 using FeCl3 as an oxidant.
Abstract: Conducting polymer composites of polypyrrole/yttrium oxide (PPy/Y2O3) were synthesized byin situ polymerization of pyrrole with Y2O3 using FeCl3 as an oxidant. The Y2O3 is varied in five different weight percentages of PPy in PPy/Y2O3 composites. The synthesized polymer composites are characterized by infrared and X-ray diffraction techniques. The surface morphology of the composite is studied by scanning electron microscopy. The glass transition temperature of the polymer and its composite is discussed by DSC. Electrical conductivity of the compressed pellets depends on the concentration of Y2O3 in PPy. The frequency dependent a.c. conductivity reveals that the Y2O3 concentration in PPy is responsible for the variation of conductivity of the composites. Frequency dependent dielectric constant at room temperature for different composites are due to interfacial space charge (Maxwell Wagner) polarization leading to the large value of dielectric constant. Frequency dependent dielectric loss, as well as variation of dielectric loss as a function of mass percentage of Y2O3 is also presented and discussed.

266 citations


Journal ArticleDOI
TL;DR: In this paper, the enhancement of the thermal conductivity of ethylene glycol in the presence of copper oxide (CuO) was investigated by using a modified transient hot wire method.
Abstract: The enhancement of the thermal conductivity of ethylene glycol in the presence of copper oxide (CuO) is investigated. CuO nanofluids are prepared in a two-step method. No surfactant is employed as a dispersant. The volume fraction of CuO nanoparticles suspended in ethylene glycol liquid is below 5 vol.-%. The crystalline phases of the CuO powders are measured with x-ray diffraction patterns (XRD). CuO nanoparticles are examined using scanning electron microscopy (SEM) to determine their microstructure. The thermal conductivities of the CuO suspensions are measured by a modified transient hot wire method. The viscosity was measured with a viscosity instrument. The results show that CuO nanofluids with low concentrations of nanoparticles have considerably higher thermal conductivities than the identical ethylene glycol base liquids without solid nanoparticles. The thermal conductivity ratio improvement for CuO nanofluids is approximately linear with the volume fraction of nanoparticles. For CuO nanoparticles at a volume fraction of 0.05 (5 vol-.%) thermal conductivity was enhanced by up to 22.4 %. CuO nanofluids thus have good potential for effective heat transfer applications.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the temperature and frequency dependence of conductivity of polymer matrix-metal particles composites and provided evidence for the charge carriers transport mechanism via the occurred agreement of experimental results with the employed hopping models (variable range hopping model and random free energy barrier model).
Abstract: Charge transport properties, such as the temperature dependent dc conductivity and the frequency dependent conductance, of polymer matrix–metal particles composites, are investigated in the present study. Dc and ac conductivity is examined with varying parameters the filler content, temperature and the frequency in the case of ac field. The examined systems, though they are characterized as dielectrics, exhibit considerable conductivity, which alters by several orders of magnitude with temperature and frequency. The temperature and frequency dependence of conductivity gives evidence for the charge carriers transport mechanism via the occurred agreement of experimental results with the employed hopping models (variable range hopping model and random free-energy barrier model).

Journal ArticleDOI
TL;DR: In this paper, the electrical properties of single-walled carbon nanotubes (SWNTs) embedded in a poly(3-octylthiophene) matrix have been investigated as a function of SWNT concentration.
Abstract: The electrical properties of single-walled carbon nanotubes (SWNTs) embedded in a poly(3-octylthiophene) matrix have been investigated as a function of SWNT concentration. The electrical conductivity and its temperature dependence were measured as a function of the SWNT concentration. As the nanotube concentration increased from 0to20wt%, the conductivity of the resulting films is dramatically increased by six orders of magnitude. The enhancement in conductivity can be explained by means of a three dimension simple percolation path theory, resulting in an estimated threshold of 4wt%. The temperature dependence of the SWNT conductivity mat obeys a three-dimensional variable range hopping. In contrast, the polymer-nanotube composite conductivity follows a fluctuation induced tunneling model. The main divergence is that in the polymer-nanotube composite, the nanotubes are coated with polymer, which acts a barrier in bundle to bundle hopping.

Journal ArticleDOI
TL;DR: Li 2 S-based oxysulfide glasses and sulfide glass-ceramics have been developed in this article, which leads to the development of a bulk-type all solid-state lithium secondary battery with excellent cycling performance.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated an ether-based electrolyte containing four different electrolyte salts to determine how electrolyte properties such as oxygen solubility, dynamic viscosity, and conductivity change with each electrolyte salt, and how this directly affects rate capability and discharge capacity.
Abstract: The practical operation of a lithium/oxygen organic electrolyte battery depends on a significant amount of dissolved oxygen transporting through the organic electrolyte permeating the carbon black cathode before its reduction occurs. The rate of oxygen transport directly influences rate capability and discharge capacity. The organic electrolyte can be tailored to maximize the transport of oxygen while still retaining the ability to form a stable solid electrolyte interface with the lithium anode, chemical stability towards the discharge products Li 2 O 2 and Li 2 O, and oxidative stability to over 3 V. We investigated an ether-based electrolyte containing four different electrolyte salts to determine how electrolyte properties such as oxygen solubility, dynamic viscosity, and conductivity change with each electrolyte salt, and how this directly affects rate capability and discharge capacity. The results indicate that discharge capacity at 0.5 mA/cm 2 is determined by dynamic viscosity alone for these electrolytes, while discharge capacity at 0.2 and 0.05 mA/cm 2 shows no correlation with either oxygen solubility, dynamic viscosity, or conductivity. Our results demonstrate that a substantial improvement in rate capability can be achieved by optimizing electrolyte viscosity.

Journal ArticleDOI
TL;DR: It is shown that the quasiparticle decay rate has a minimum as a function of energy, there is a universal minimum value for the in-plane conductivity of order e(2)/h per plane and, unexpectedly, the c-axis conductivity is enhanced by disorder at low doping, leading to an enormous conductivity anisotropy at low temperatures.
Abstract: We study the effects of disorder in the electronic properties of graphene multilayers, with special focus on the bilayer and the infinite stack. At low energies and long wavelengths, the electronic self-energies and density of states exhibit behavior with divergences near half filling. As a consequence, the spectral functions and the conductivities acquire anomalous properties. In particular, we show that the quasiparticle decay rate has a minimum as a function of energy, there is a universal minimum value for the in-plane conductivity of order e(2)/h per plane and, unexpectedly, the c-axis conductivity is enhanced by disorder at low doping, leading to an enormous conductivity anisotropy at low temperatures.

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the ionic conductivity of the chitosan-NH 4 CF 3 SO 3 system over a wide range of frequency and at temperatures between 298 and 313 k. The temperature dependent conductivity data obeys Arrhenius relationship.
Abstract: Ionic conductivity for the chitosan-NH 4 CF 3 SO 3 system was conducted over a wide range of frequency and at temperatures between 298 and 313 K. Dielectric data were analyzed using complex permittivity e * and complex electrical modulus M * for the sample with the highest ionic conductivity at various temperatures. The temperature-dependent conductivity data obeys Arrhenius relationship. Jonschers universal power law was used to analyze AC conductivity of the sample. Hopping frequency was determined and activation energy of hopping is almost equal to the activation energy of conduction. The AC conductivity master curve was obtained for the highest conducting sample when scaled vertically by σ DC and horizontally by ω P .

Patent
09 Mar 2006
TL;DR: In this paper, a photonic crystal structure is formed in an n-type layer of a III-nitride light emitting device on a tunnel junction, where a second layer separates the first layer of first conductivity type from a third layer of second conductivity types.
Abstract: A photonic crystal structure is formed in an n-type layer of a III-nitride light emitting device. In some embodiments, the photonic crystal n-type layer is formed on a tunnel junction. The device includes a first layer of first conductivity type, a first layer of second conductivity type, and an active region separating the first layer of first conductivity type from the first layer of second conductivity type. The tunnel junction includes a second layer of first conductivity type and a second layer of second conductivity type and separates the first layer of first conductivity type from a third layer of first conductivity type. A photonic crystal structure is formed in the third layer of first conductivity type.

Patent
03 Oct 2006
TL;DR: In this paper, a method of manufacturing a semiconductor device in which a trench groove is formed in a first conductivity type semiconductor layer, and a second conductivity typesence layer is epitaxially grown so as to bury the trench groove was proposed.
Abstract: A method of manufacturing a semiconductor device in which a trench groove is formed in a first conductivity type semiconductor layer, and a second conductivity type semiconductor layer is epitaxially grown so as to bury the trench groove. The second conductivity type semiconductor layer is then removed until a surface of the first conductivity type semiconductor layer is exposed. The first conductivity type semiconductor layer is epitaxially grown on the first conductivity type semiconductor layer and the second conductivity type semiconductor layer such that the thickness of the first conductivity type semiconductor layer increases by a length which is substantially the same as a depth of the trench groove. The first conductivity type semiconductor layer is selectively removed such that the second conductivity type semiconductor layer is exposed, and the epitaxially growing of the second conductivity type semiconductor layer is repeated through selectively removing the first conductivity type semiconductor layer.

Journal ArticleDOI
TL;DR: In this paper, conducting polyaniline/tungsten oxide (WO 3 ) composites have been synthesized by "in situ" deposition technique by placing fine graded WO 3 in polymerization mixture of aniline.
Abstract: Conducting polyaniline/tungsten oxide (WO 3 ) composites have been synthesized by ‘in situ’ deposition technique by placing fine graded WO 3 in polymerization mixture of aniline. This is a single step polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The results were also well supported by FTIR spectral analysis, scanning electron microscope (SEM), XRD and conductivity measurements. High temperature conductivity measurements show thermal activated behavior. The change in resistance with respect to percent relative humidity (RH) is observed. The composites in the pellet form exhibit almost linear behavior within a chosen range of humidity (ranging between 10 and 95% RH).

Journal ArticleDOI
TL;DR: In this paper, conductivity relaxation behaviors of cathode materials were investigated at temperature 400-550 degrees C. Generally, Ba0.2O3-delta and Ba 0.5Sr0.5Co0.8Fe0.
Abstract: BaxSr1-xCo0.8Fe0.2O3-delta (0.3 0.5 compositions. Furthermore, conductivity relaxation behaviors were also investigated at temperature 400-550 degrees C. Generally, Ba0.4Sr0.6Co0.8Fe0.2O3-delta and Ba0.5Sr0.5Co0.8Fe0.2O3-delta are potential cathode materials. (c) 2005 Elsevier Ltd. All rights reserved.

Journal ArticleDOI
TL;DR: In this article, the electrical properties of nanostructured, heavily yttria- or samaria-doped ceria ceramics are studied as a function of grain size using electrochemical impedance spectroscopy (EIS).
Abstract: The electrical properties of nanostructured, heavily yttria- or samaria-doped ceria ceramics are studied as a function of grain size using electrochemical impedance spectroscopy (EIS). A remarkable enhancement in the total ionic conductivity of about one order of magnitude is found in nanostructured samples, compared with the intrinsic bulk conductivity of conventional microcrystalline ceramics. This effect is attributed to the predominance of grain-boundary conduction in the nanostructured materials, coupled with an increase in the grain-boundary ionic diffusivity with decreasing grain size.

Journal ArticleDOI
TL;DR: The use of electrostatic charge injection (i.e., the transverse field effect) to induce both very large two-dimensional hole densities and metallic conductivities in poly(3-hexylthiophene) (P3HT) is reported in this paper.
Abstract: The use of electrostatic charge injection (i.e., the transverse field effect) to induce both very large two-dimensional hole densities (∼ 1015 charges cm–2) and metallic conductivities in poly(3-hexylthiophene) (P3HT) is reported. Films of P3HT are electrostatically gated by a solution-deposited polymer-electrolyte gate dielectric in a field-effect-transistor configuration. Exceptionally high hole field-effect mobilities (up to 0.7 cm2 V–1 s–1) are measured concurrently with large hole densities, resulting in an extremely large sheet conductance of 200 μS sq.–1. The large room-temperature conductivity of 1000 S cm–1 together with the very low measured activation energies (0.7–4 meV) suggest that the metal–insulator transition in P3HT is achieved. A maximum in sheet conductance versus charge density is also observed, which may result from near-filling of the valence band or from charge correlations that lower the carrier mobility. Importantly, the large hole densities in P3HT are achieved using capacitive coupling between the polymer-electrolyte gate dielectric and P3HT (i.e., the field effect) and not via chemical or electrochemical doping. Electrostatic control of carrier density up to 1015 charges cm–2 (∼ 1022 charges cm–3) opens opportunities to explore systematically the importance of charge-correlation effects on transport in conjugated polymers without the structural rearrangement associated with chemical or electrochemical doping.

Journal ArticleDOI
TL;DR: The irreversible conductivity decay exhibited by Nafion 117 membranes above certain values of temperature and relative humidity (RH) has been investigated by two-probe impedance measurements carried out at 120°C with the electric field normal to the membrane surface, under controlled applied pressure on the electrodes as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this article, intermediate-high molecular weight poly[2,2-(m -phenylene)-5,5-bibenzimidazole] has been produced by mixing 3,3′,4, 4,4′-tetraminobiphenyl and isophthalic acid in polyphosphoric acid as polycondensing agent and triphenyl phosphite as catalyst.

Journal ArticleDOI
TL;DR: In this article, an evaluation of the transport properties of super ion conducting quaternary system 20CdI 2 −80[ x Ag 2 O− y (0.7V 2 O 5 −0.3B 2 O 3 )], where 1 ≤ ǫ x / y  ≥ 3, in steps of 0.25, to study the effect of changing the modifier to former ratio on the conduction phenomena has been undertaken.

Journal ArticleDOI
Davide Mattia1, M P Rossi1, B M Kim1, G Korneva1, Haim H. Bau1, Yury Gogotsi1 
TL;DR: This paper presents a strategy for modifying the surface chemistry, wettability, and electrical conductivity of carbon tubes and films through annealing in a vacuum with 60-300 nm nanotubes (nanopipes).
Abstract: The use of carbon nanomaterials in various applications requires precise control of their surface and bulk properties. In this paper, we present a strategy for modifying the surface chemistry, wettability, and electrical conductivity of carbon tubes and films through annealing in a vacuum. Experiments were conducted with 60−300 nm nanotubes (nanopipes), produced by noncatalytic chemical vapor deposition (CVD) in a porous alumina template, and with thin films deposited by the same technique on a glassy carbon substrate having the same structure and chemistry of the CNTs. The surface of the as-produced CVD-carbon, treated with sodium hydroxide to remove the alumina template, is hydrophilic, and the bulk electrical conductivity is lower by a factor of 20 than that of fully graphitic multiwalled nanotubes (MWNT) or bulk graphite. The bulk electrical conductivity increases to the conductivity of graphite after annealing at 2000 °C in a high vacuum. The analysis of CNTs by transmission electron microscopy (TEM)...

Journal ArticleDOI
TL;DR: In this article, a solution casting technique was used to extract polyvinyl acetate (PVAc) and poly(methylmethacrylate) (PMMA) as a host polymer and LiClO 4 as a dopant.

Journal ArticleDOI
TL;DR: In this article, the conductivity of a number of mixtures formed between ionic liquids and molecular liquids (ML) were investigated at several temperatures with the use of impedance spectroscopy.

Journal ArticleDOI
TL;DR: In this paper, a polymer memory device with an active layer consisting of conjugated poly3-hexylthiophene and gold nanoparticles capped with 1-dodecanethiol sandwiched between two metal electrodes is presented.
Abstract: Electrical bistability is demonstrated in a polymer memory device with an active layer consisting of conjugated poly3-hexylthiophene and gold nanoparticles capped with 1-dodecanethiol sandwiched between two metal electrodes. The device was fabricated through a simple solution processing technique and exhibited a remarkable electrical bistable behavior. Above a threshold voltage the pristine device, which was in a low conductivity state, exhibited an increase in conductivity by more than three orders of magnitude. The device could be returned to the low conductivity state by applying a voltage in the reverse direction. The electronic transition is attributed to an electric-field-induced charge transfer between the two components in the system. The conduction mechanism changed from a charge-injection-controlled current in the low conductivity state to a charge-transport-controlled current in the high conductivity state. In the high conductivity state the conduction was dominated by a field-enhanced thermal excitation of trapped charges at room temperature, while it is dominated by charge tunneling at low temperatures. The device exhibited excellent stability in both the conductivity states and could be cycled between the two states for numerous times. The device exhibits tremendous potential for its application as fast, stable, low-cost, high storage density nonvolatile electronic memory. © 2006 American Institute of Physics. DOI: 10.1063/1.2337252