Nickel Filaments Research Articles

Resistive Switching and Current Conduction Mechanisms in Hexagonal Boron Nitride Threshold Memristors with Nickel Electrodes

AbstractThe 2D insulating material hexagonal boron nitride (h‐BN) has attracted much attention as the active medium in memristive devices due to its favorable physical properties, among others, a wide bandgap that enables a large switching window. Metal filament formation is frequently suggested for h‐BN devices as the resistive switching (RS) mechanism, usually supported by highly specialized methods like conductive atomic force microscopy (C‐AFM) or transmission electron microscopy (TEM). Here, the switching of multilayer hexagonal boron nitride (h‐BN) threshold memristors with two nickel (Ni) electrodes is investigated through their current conduction mechanisms. Both the high and the low resistance states are analyzed through temperature‐dependent current–voltage measurements. The formation and retraction of nickel filaments along boron defects in the h‐BN film as the resistive switching mechanism is proposed. The electrical data are corroborated with TEM analyses to establish temperature‐dependent current–voltage measurements as a valuable tool for the analysis of resistive switching phenomena in memristors made of 2D materials. The memristors exhibit a wide and tunable current operation range and low stand‐by currents, in line with the state of the art in h‐BN‐based threshold switches, a low cycle‐to‐cycle variability of 5%, and a large On/Off ratio of 107.

Formation and Properties of Electron- and Ion-Conducting Layers of N-Substituted PVC Derivatives Grafted onto Active Carbon

A systematization is presented of studies of carbon sorbent functionalization based on chemical modification of the active carbon surface by covalent grafting of macromolecular N-substituted cyclic amines. Thus, porous electron-conducting and luminescent layers grafted onto supports are obtained. The layers can sorb organic compounds. After sorption of acids, hydroxides, and metal salts, the layers become electron- and ion-conducting. Here, hydrogen is formed as in cathodically polarized electrochemical bridges and oxygen is formed as in anodically polarized electrochemical bridges. Principles of layer formation are considered on the surface of the material of cellulose fibers and asbestos cloth, as well as nickel filaments. Specific features of such functionalized sorbents are shown.

Self-assembly of a drop pattern from a two-dimensional grid of nanometric metallic filaments

We report experiments, modeling and numerical simulations of the self--assembly of particle patterns obtained from a nanometric metallic square grid. Initially, nickel filaments of rectangular cross section are patterned on a SiO$_2$ flat surface, and then they are melted by laser irradiation with $\sim 20$ ns pulses. During this time, the liquefied metal dewets the substrate, leading to a linear array of drops along each side of the squares. The experimental data provides a series of SEM images of the resultant morphology as a function of the number of laser pulses or cumulative liquid lifetime. These data are analyzed in terms of fluid mechanical models that account for mass conservation and consider flow evolution with the aim to predict the final number of drops resulting from each side of the square. The aspect ratio, $\delta$, between the square sides' lengths and their widths is an essential parameter of the problem. Our models allow us to predict the $\delta$-intervals within which a certain final number of drops are expected. The comparison with experimental data shows a good agreement with the model that explicitly considers the Stokes flow developed in the filaments neck region that lead to breakup points. Also, numerical simulations, that solve the Navier-Stokes equations along with slip boundary condition at the contact lines, are implemented to describe the dynamics of the problem.

Research on resistive switching mechanism of multi-filaments formation/rupture in nickel oxide thin films

Resistive switching (RS) effect has attracted enormous attention due to its potential for application of resistive random access memory with fast speed, good scalability and high endurance. NiO is a model system of RS effect, in which the formation/rupture of nickel filaments is directly related to the RS effect. In fact, it is still controversial that the RS effect in NiO films should be attributed to whether a single filament or multi-filaments. In this work, we demonstrate that multi-filaments are involved in the RS process by means of conventional I-V measurements, conductive atomic force microscopy and transmission electron microscopy. Furthermore, we observed the interesting tunneling magnetoresistance in this system for the first time, which not only reveals the mechanism of multi-filaments, but also provides a new way for multifunctional devices.

Magnetism as a probe of the origin of memristive switching in p-type antiferromagnetic NiO

We induced bipolar resistive switching in p-type nickel oxide. By probing the magnetic properties of the films, we proved that bipolar resistive switching in this antiferromagnetic oxide was due to the formation and rupture of oxygen-vacancy filaments, rather than electrochemical growth and dissolution of nickel-ion filaments. In the low resistive state, oxygen-mediated super-exchange interaction was suppressed along the conductive paths. This led to a reduction of the saturation moment but not the appearance of a ferromagnetic phase, excluding the formation of nickel filaments.

(Ni—Ni—Ni)@(Ge9)2]4‐: A Linear Triatomic Nickel Filament Enclosed in a Dimer of Nine‐Atom Germanium Clusters.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Effect of mixing process on electromagnetic interference shielding effectiveness of nickel/acrylonitrile–butadiene–styrene composites

AbstractThis article reports the effect of the mixing process on the electromagnetic interference (EMI) shielding effectiveness of nickel/acrylonitrile–butadiene–styrene (ABS) composites. Nickel in either powder or filament form was used as the filler material. It was mixed with ABS by two mixing processes: one was the Brabender‐mixing method, in which nickel was mixed in the polymer melt by a strong shear at high temperatures, and the other was a simple dry mixing method performed in a centrifugal ball mill. Our results showed that the dry‐mixing method could produce EMI shielding effectiveness of 36 dB at the 3 vol % nickel filaments level. In contrast, we need 20 vol % nickel powder to exhibit some shielding effectiveness for the Brabender method. After the nondestructive X‐ray examination and four‐point probe resistivity measurements, we concluded that better EMI shielding effectiveness could be achieved when the mixing method provided a state of uniformity on the macroscale, but not on the microscale. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 128–135, 2005

A comparative study of carbons for use as an electrically conducting additive in the manganese dioxide cathode of an electrochemical cell

using continuous carbon-fiber carbon-matrix and polymer– untreated fibers are used. The activation treatment does not matrix composites. Comp Part B: Eng 1999;30(3):227–31. degrade the tensile properties of the fibers. [3] Sau KP, Chaki TK, Chakraborty A, Khastgir D. Electromagnetic interference shielding by carbon black and carbon fibre filled rubber composites. Plastics Rubber Comp Process Acknowledgements Appl 1997;26(7):291–7. [4] Ramadin Y, Jawad SA, Musameh SM, Ahmad M, Zihlif AM, Technical assistance by Weiming Lu of this University Paesano A et al. Electrical and electromagnetic shielding is appreciated. behavior of laminated epoxy–carbon fiber composite. Polymer Int 1994;34(2):145–50. [5] Huang CY, Pai JF. Studies on processing parameters and thermal stability of ENCF/ABS composites for EMI shieldReferences ing. J Appl Polym Sci 1997;63(1):115–23. [6] Shui X, Chung DDL. Submicron diameter nickel filaments [1] Chung DDL. Materials for electromagnetic interference and their polymer–matrix composites. J Mater Sci shielding. J Mater Eng Perform 2000;9(3):350–4. 2000;35:1773–85. [2] Luo X, Chung DDL. Electromagnetic interference shielding

Gas chromatographic analysis of trace impurities in chlorine trifluoride

The gas chromatographic determination of trace gaseous impurities in highly reactive fluorinated gaseous matrices presents unique requirements to both equipment and techniques. Especially problematic are the gases normally present in ambient air namely oxygen and nitrogen. Analysing these gases at the low μl/l (ppm) level requires special equipment and this publication describes a custom-designed system utilising backflush column switching to protect the columns and detectors. A thermal conductivity detector with nickel filaments was used to determine ppm levels of impurities in ClF 3.

Submicron diameter nickel filaments and their polymer-matrix composites

Discontinuous nickel filaments of diameter 0.4 μm and having a carbon core of diameter 0.1 μm were fabricated by electroplating nickel on discontinuous carbon filaments. They exhibited a grain size of 0.016 μm and electrical resistivity of about 5 × 10−6 Ω·cm. In an amount as low as 7 vol.% in a polymer (polyether sulfone) matrix, they resulted in a composite exhibiting electromagnetic interference shielding effectiveness of 87 dB and reflection coefficient 0.95 at 1–2 GHz, tensile strength 52 MPa, tensile ductility 1.0%, and density 1.87 g/cm3.

Pressure-dependent conduction behavior of various particles for conductive adhesive applications

Abstraet-The efficiency of electrical conduction in particle-filled conductive adhesives largely depends on the interparticle conduction. In order to gain insight into the pressure-dependent conduction behavior with particles of different sizes, shapes, and types, the effects of external pressure on the filler resistance were measured by the four-point probe method using different conductive fillers. The following types of particles were used: Ni powder, Ni flake, Ag powder, Ni filament, magnetite spindles, and Cu particles. Non-filament particle size was in the range 0.7-44 μm. The filaments were 20 μm in diameter and 160 or 260 μm in length. The particle treatment procedures investigated included silver coating using different methods, and the use of acid solutions including H3PO4, HF, and HCl to etch and remove the surface oxide layer. Resistivity levels were measured using a nonconductive hollow cylinder plunger device developed in our laboratories. The results of our work showed that when the pressure was increased by ten-fold from 0.7 to 7 MPa, the resistivity of some of the particles decreased substantially (e.g. 45-fold in the case of magnetite spindles, 20-fold in the case of 9 μm nickel powder). For some other particles, however, the change was not as significant (e.g. 50% reduction for 4-7 μm silver powder). As a result, 1-5 μm nickel flakes, as well as 260 μm nickel filaments of 20 μm diameter, coated with 0.033 M AgNO3 had lower resistivities at 7 MPa compared with the resistivity of the 4-7 μm silver powder at 0.7 MPa. Etching of 6-7 μm copper particles with 20% H3PO4 solution yielded 9.42 mΩ cm resistivity for these particles at 7 MPa. Our experimental results also indicated that the HCl etch procedure increased the packing efficiency in Ni particles of three-dimensional nature (i.e. powder and filaments) and also reduced the tunnel resistivity.

0.4 μm Diameter Nickel-Filament Silicone-Matrix Resilient Composites for Electromagnetic Interference Shielding

Resilient silicone-matrix composites containing 7–13 volume percent nickel filaments (0.4 μm diameter) exhibited 74–93 dB electromagnetic interference (EMI) shielding effectiveness at 1–2 GHz and 1 × 10−1 – 2 × 10−2 Ω cm DC volume electrical resistivity. The high shielding effectiveness is due to the small diameter of the nickel filaments. The composites are useful for EMI shielding gaskets and cable jackets.

Nickel filament polymer-matrix composites with low surface impedance and high electromagnetic interference shielding effectiveness

The processing of nickel filaments of 0.4 Μm diameter gives polyethersulfone-matrix composites with high electromagnetic interference shielding effectiveness, high reflection coefficient and low surface impedance at 1-2 GHz. With 7 vol.% nickel filaments, the composite exhibited shielding effectiveness 87 dB (compared to 90 dB for solid copper), surface impedance 1.2 Ω (same as for solid copper), tensile strength 52 MPa, modulus 5 GPa, ductility 1.0%, and density 1.87 g/cm3.

A new electromechanical effect in discontinuous-filament elastomer-matrix composites

A new electromechanical effect in which the volume electrical resistivity decreased upon tensile loading and increased upon unloading was observed in elastomer- (silicone-) matrix composites with a discontinuous and randomly oriented nickel filament filler. The effect is probably due to the increase in filament alignment upon tensile loading. It allows tensile strain sensing. However, filament - matrix interface degradation caused the resistivity to increase irreversibly and the electromechanical effect to diminish as cycling progressed beyond the first 10 - 30 cycles.

Silver coating of spindle- and filament-type magnetic particles for conductive adhesive applications

Spindle-type hematite and magnetite particles and nickel filaments have been coated uniformly with silver by using chemical reduction. The effects of the reaction time and the concentration and nature of the reducing agent on the particle coatings were investigated at constant temperature. The reaction time had a pronounced effect on the nature of the coated surface layer. Coated and core particles were examined by scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). The electrical properties of the particles were also characterized. The conductivity of nickel filaments which can be oriented under a magnetic field for anisotropic electric conduction increased from 302 to 877 S/cm at 3.5 kPa pressure when coated with silver.

Magnetic properties of nickel filament polymer-matrix composites

The magnetic properties of polyethersulfone-matrix composites with 3-19 vol.% polycrystalline nickel filaments (0.4 (im diam) were investigated. These filaments were found to exhibit hysteresis energy loss 10800 J/m3 of nickel and coercive force 16.9 kA/m, compared to corresponding values of 4930 J/m3 and 4.7 kA/m for 2 μ.m diam polycrystalline nickel fibers, 1020 J/m3 and 0.5 kA/m for 20 μm diam polycrystalline nickel fibers, and 1280 J/m3 and 2.3 kA/m for solid polycrystalline nickel.

Submicron nickel filaments made by electroplating carbon filaments as a new filler material for electromagnetic interference shielding

Short nickel filaments of diam 0.4 μm and containing 94 vol% Ni and 6 vol% C were fabricated by electroplating with nickel 0.1 μm diam catalytically grown carbon filaments. The use of these filaments in polyether sulfone in amounts of 3, 7,13, and 19 vol% gave composites with electromagnetic interference shielding effectiveness at 1–2 GHz of 42,87,84, and 92 dB, respectively, compared to a value of 90 dB for solid copper. Less shielding was attained when 0.1 μm diam carbon filaments or 2 or 20 μm diam nickel fibers were used instead.

Nickel Filament Polymer-Matrix Composites with Low Surface Impedance and High Electromagnetic Interference Shielding Effectiveness

ABSTRACTNickel filaments of 0.4 μm diameter gave polyethersulfone-matrix composites with high electromagnetic interference shielding effectiveness and low surface impedance at 1–2 GHz. With 7 vol.% nickel filaments, the composite exhibited shielding effectiveness 87 dB (compared to 90 dB for solid copper), surface impedance 1.2 Ω (same as for solid copper), tensile strength 52 MPa, modulus 5 GPa, ductility 1.0% and density 1.87 g/cm3. The low surface impedance is valuable for microwave waveguides.

Low blank rhenium isotope ratio determinations by V 2O 5 coated nickel filaments using negative thermal ionization mass spectrometry

Thenium isotope ratio determinations are, in principle, possible by negative thermal ionization mass spectrometry (NTI-MS). Relatively high rhenium blanks from the commonly-used filament materials prevent accurate isotope ratio determinations, especially for small rhenium sample amounts which are of importance, for example, in geochronology in connection with the Re/Os dating method. Platinum and nickel filaments were tested by different preparation techniques to reduce the rhenium blank contribution from the filament material. The lowest rhenium blank of less than 1 pg was achieved by coating nickel filaments with V 2O 5 prior to degassing under high vacuum conditions at 850°C. Obviously, the vanadium—nickel oxide layer formed on the surface of the filament during this process prevents further emission of rhenium ions from the filament material. Using Ba(OH) 2 for the enhancement of negative thermal ions, 1 ng of rhenium resulted in ion currents at the detector side of about 10 −11 A with an ionization efficiency of up to 20%. The 185Re/ 187Re isotope ratio of a sample of natural isotopic composition could be determined to be 0.59818 ± 0.00026 with a relative precision of 0.04%. The isotope ratio determination for an 187Re spike was comparable in precision but the relative standard deviation of an 185Re spike was significantly higher, which could be explained by mass fractionations of oxygen in the measured ReO − 4 ion. The ReO − 4 ion is about 200 to 2500 times more abundant than the only other detectable rhenium ion in NTI-MSReO − 3. The ReO − 4/ReO − 4 ratio decreases with increasing temperature. By the low blank NTI-MS technique described in this work, more precise and accurate determinations of the rhenium isotope ratio and the rhenium concentration by isotope dilution analysis from nanogramme samples are possible.

ChemInform Abstract: KINETICS OF THE DECOMPOSITION AND HYDROGEN REDUCTION OF NITRIC OXIDE ON NIOBIUM, NICKEL AND PLATINUM FILAMENTS AT HIGH TEMPERATURES AND LOW PRESSURES

Chemischer InformationsdienstVolume 9, Issue 7 Physical Inorganic Chemistry ChemInform Abstract: KINETICS OF THE DECOMPOSITION AND HYDROGEN REDUCTION OF NITRIC OXIDE ON NIOBIUM, NICKEL AND PLATINUM FILAMENTS AT HIGH TEMPERATURES AND LOW PRESSURES J. A. MORGAN, Search for more papers by this authorA. J. B. ROBERTSON, Search for more papers by this author J. A. MORGAN, Search for more papers by this authorA. J. B. ROBERTSON, Search for more papers by this author First published: February 14, 1978 https://doi.org/10.1002/chin.197807026AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue7February 14, 1978 RelatedInformation