Electrical Conductivity Characteristics Research Articles

Exploiting both optical and electrical anisotropy in nanowire electrodes for higher transparency

Transparent electrodes such as indium tin oxide and random meshes of silver nanowires (AgNWs) have isotropic in-plane properties. However, we show that imparting some alignment to AgNWs can create anisotropic transparency and electrical conductivity characteristics that may benefit many applications. For example, liquid crystal displays and the touch sensors on top of them often only need to be transparent to one type of polarized light as well as predominantly conductive in only one direction. Herein, AgNWs are slightly preferentially aligned during their deposition by rod coating. Compared to randomly oriented AgNW films, the alignment boosts the transparency to perpendicularly polarized light, as well as achieves a higher transparency for a given sheet resistance in one direction compared to randomly oriented AgNWs films. These factors together increase the transparency of a 16 Ω/sq electrode by 7.3 percentage points. The alignment technique is cheap and scalable, compatible with roll-to-roll processes, and most importantly does not require extra processing steps, as rod coating is already a standard process for AgNW electrode fabrication.

A novel assembled carbon black/carbon nanotubes (CB/MWCNT) nano-structured composite for pressure-sensitive conductive silicon rubber (SR)

In this paper, a novel “grape string” carbon black/multi-wall carbon nanotubes (CB/MWCNT) structure was obtained by electro-static assembly method to enhance the resistance stability of the carbon material filled silicone rubber (SR). Carbon black (CB) and multi-wall carbon nanotubes (MWCNT) were surface modified by sulfonic dodecyl benzene sodium and cetyltrimethylammonium bromide to provide negatively charge and positively charge, respectively. Electric conductive sheet of CB/MWCNT/SR composite was obtained by mixing and vulcanizing. The assembly effect and dispersion state of the composites were analyzed by transmission electron microscopy and scanning electron microscopy. The electrical conductivity and dynamic pressure-resistance characteristic of CB/MWCNT/SR with different doping ratio and dosage were tested. The results show that the proper weight ratio 3:2 of CB:MWCNT for electrostatic assembly can cause the stable “grape string” nano-structure. The conductivity and pressure-resistance characteristic are superior when the volume fraction of “grape string” nano-composites reaches 22%, which will provided with less filler fraction and better stress sensitivity, compared with single component carbon black filler.

Influence of the ligand nature on the in situ laser-induced synthesis of the electrocatalytically active copper microstructures

In this work we demonstrate the role of a ligand in formation of the conductive and electrocatalytically active copper microstructures produced using the in situ laser-induced metal deposition technique. For this purpose, the alkaline solutions of different concentrations containing copper(II) chloride and Rochelle salt, which is used as the ligand and exhibits both coordination and reduction properties, were studied by ATR-FTIR, UV–Vis, and Raman spectroscopy. According to spectroscopic studies and theoretical considerations, it was observed that at certain concentrations and proportion of copper(II) chloride and sodium potassium tartrate, and also within pH range between 7 and 13 the components of the plating copper solution form the tartrate copper complex, in which copper ion is coordinated by four hydroxyl groups of the ligand and two hydroxyl groups of the environment. As a result, the laser-induced deposition from solutions, where copper coordination occurs via hydroxyls rather than through other functional groups (e.g. carboxylate), results in the synthesis of the sensory active materials. Furthermore, we figured out that the presence of the reducing agents such as polyols in the plating copper solution also enhances the electrical conductivity and electrochemical characteristics of the resulting copper microdeposits, among which sorbitol displays the most attractive results. Thus, it was shown that the regime of copper coordination in an organic ligand and number of hydroxyl groups in a ligand and a reducing agent directly affect the properties of the synthesized copper microstructures. In addition, the overall results obtained in this study are quite useful for better understanding the mechanisms of the laser-induced metal deposition process, and very perspective for development and design of new non-enzymatic electrochemical sensors and biosensors.

Tunable structural and electrical impedance properties of pyrochlores based Nd doped lanthanum zirconate nanoparticles for capacitive applications

Pyrochlore structure based compounds have shown valuable interest in practical applications because of their structure tunability and stability. In this context, the stability of pyrochlore structure in a particular phase is quite essential for practical optimization of valuable dielectric and impedance characteristics of rare-earth zirconates. Thus, in the present work, a series of Nd substituted lanthanum zirconates were synthesized to investigate its effect on the structural, morphological, electrical and dielectric properties. Structural analysis confirmed the formation of sustainable pyrochlore phase in all the samples having space group Fd3m. A drastic reduction in grain size with Nd substitution was visualized by the images obtained using a field-emission scanning electron microscope. The electrical impedance spectroscopy was performed to check the frequency response of the dielectric behaviour, giving tenable information about changes in electrical permittivity due to Nd substitution. Impedance analysis shows a contribution of grains and grain boundaries in these heterogeneous zirconate samples. These regions are easily distinguishable in the sense of their electrical conductivity and impedance characteristics. The conductivity values obtained were lying in the range of nano-Farad predicted these materials to be used as solid oxide fuel cells.

Electrokinetic characteristics of initial porous glasses and those modified with titanium- and aluminum-oxide particles

The structural (volume porosity, structural resistance coefficient, and average pore radius) and electrokinetic (specific electrical conductivity, ion-transport numbers, and electrokinetic potential) characteristics of macroporous glass membranes obtained from two-phase sodium-borosilicate glasses with different times of thermal treatment have been studied in solutions of hydrochloric acid and potassium chloride. The properties of the initial membranes have been compared with the characteristics of the same membranes modified by filtering through them suspensions of aluminum- and titanium-oxide nanoparticles with different weight concentrations. It has been shown that, at low degrees of pore channel surface coverage with nanoparticles (<0.1), the structural parameters of the membranes remain almost unchanged. In addition, it has been found that the presence of positively charged nanoparticles on the negatively charged surface increases the surface conductivity and the absolute value of the electrokinetic potential.

Propagation of superconducting coherence via chiral quantum-Hall edge channels

Recently, there has been significant interest in superconducting coherence via chiral quantum-Hall (QH) edge channels at an interface between a two-dimensional normal conductor and a superconductor (N–S) in a strong transverse magnetic field. In the field range where the superconductivity and the QH state coexist, the coherent confinement of electron- and hole-like quasiparticles by the interplay of Andreev reflection and the QH effect leads to the formation of Andreev edge states (AES) along the N–S interface. Here, we report the electrical conductance characteristics via the AES formed in graphene–superconductor hybrid systems in a three-terminal configuration. This measurement configuration, involving the QH edge states outside a graphene–S interface, allows the detection of the longitudinal and QH conductance separately, excluding the bulk contribution. Convincing evidence for the superconducting coherence and its propagation via the chiral QH edge channels is provided by the conductance enhancement on both the upstream and the downstream sides of the superconducting electrode as well as in bias spectroscopy results below the superconducting critical temperature. Propagation of superconducting coherence via QH edge states was more evident as more edge channels participate in the Andreev process for high filling factors with reduced valley-mixing scattering.

동남극 GV7 천부 빙하코어의 전기 전도도 특성

빙하코어의 전기 전도도는 주로 얼음의 산성도에 의하여 결정되는 것으로 알려져 있다. 빙하코어의 산성도를 두드러지게 증가시키는 대표적인 물질로는 화산활동에 의해 대기로 방출된 H2SO4, HNO3, HCl, HF가 있다. 따라서 전기 전도도 측정법(electrical conductivity measurement, ECM)을 빙하코어에 적용하였을 때 관찰되는 뚜렷한 피크들은 과거 화산활동을 지시할 수 있다. 만일 분출 시기가 알려진 화산 활동이 확인된다면 이를 빙하코어의 연대측정에 활용할 수 있다. 본 연구에서는 2013-2014년 남극 하계 시기에 한-이태리 공동시추 프로그램을 통하여 동남극 GV7(70°41

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

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

Electrical conductivity and piezo-resistive characteristics of CNT and CNF incorporated cementitious nanocomposites under static and dynamic loading

The present study deals with the conductivity of carbon nano fiber (CNF) or nano tube (CNT) incorporated cement composite under static and dynamic conditions. Since, microstructure of cement matrix changes during hydration process, the influence of the conduction path on the conductive properties of composite is required to be evaluated. Role of the synthesis process using ultrasonication, type of fiber, % of fiber, etc. to develop the piezo sensitive CNT/CNF composite is investigated. The influence of external voltage to overcome the threshold resistance of the nanocomposite matrix is also investigated. Gauge factors of the developed conductive cement based composites are evaluated. Further, dynamic load sensitive CNT cement nanocomposite is developed, using the developed material with consistent piezo-resistive properties, for measuring the acceleration response of the structures. It is found that the cement based nanocomposite sensors as developed in the present study are good candidate for real time health monitoring of structures.

Arousal Retention Effect of Magnetic Stimulation to Car Drivers Preventing Drowsy Driving without Sleep Rebound

SUMMARYWe report experimental validation of the existence of so‐called the sleeping rebound phenomenon against each sensory stimulus using a driving simulator and the electroencephalograph for about 105 subjects with evaluation of an arousal index (α + β)/(δ + θ) in the electroencephalogram measurements after each driving operation. We found that methods using the perfume presentation, the alert presentation, the vibration, and chewing gum were resulted in the sleeping rebound phenomenon, while a proposed magnetic stimulation showed an arousal retention effect without the sleeping rebound. Mechanisms of the arousal effect of the magnetic stimulation were discussed with measurements of electric conductivity versus water temperature characteristics of pure water.

AC conduction mechanism of the zinc potassium diphosphate

Zinc potassium pyrophosphate K2ZnP2O7 was synthesized using the conventional solid-state reaction. X-ray powder diffraction analysis proves the formation of a pure phase which crystallizes in the tetragonal system. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 614–718 K and 200 Hz–1 MHz, respectively, by means of impedance spectroscopy. The alternating current (AC) conductivity for grain contribution follows the universal Jonscher’s power law. The frequency exponent s is temperature independent and equal to 0.8. The QMT model was proposed to be the most suitable model to characterize the electrical conduction mechanism in the titled sample. Dielectric data were analyzed using complex electrical modulus M* at various temperatures. The bulk relaxation time was found from the peaks position of the above spectra and the thermodynamic parameters were also found using the Eyring theory.

Single-crystal Cr2O3 nanoplates with differing crystalinities, derived from trinuclear complexes and embedded in a carbon matrix, as an electrode material for supercapacitors

As one kind of important p-type semiconductors, Cr2O3 has been widely used for optical and electronic devices due to its high electrical conductivity and special optoelectronic characteristics, as well as high chemical and thermal stability. In this paper, single-crystalline Cr2O3 nanoplates embedded in carbon matrix were successfully synthesized through direct thermal decomposition of a trinuclear cluster complex of [Cr3O(CH3CO2)6(H2O)3]NO3·CH3COOH ([Cr3O]) in Ar atmosphere. The synergetic effect of the plate-like structure and embedding in carbon matrix contributes to the enhanced electrochemical performance of the Cr2O3-C nanoplates. Owing to different crystallinity and composition, the obtained products at 400, 500, 600, and 700°C with different carbon content of 12.52, 8.26, 5.35 and 3.27% exhibited enhanced battery-type electrode materials in three-electrode system with high specific capacitance (823.11, 781.65, 720.72, and 696.73Fg−1 at 1Ag−1) and remarkable cycling stability (about 0.3, 2.7, 4.5 and 5.6% loss of its initial capacitance after 5000 charge-discharge cycles at a current density of 5Ag−1). Furthermore, an assembled asymmetric device (Cr2O3-C nanoplates (positive electrode)//activated carbon (AC, negative one)) with an extended operating voltage window of 1.8V achieves a specific capacitance of 58.06Fg−1 at the current density of 1Ag−1 and an energy density of 26.125Whkg−1 at power density of 0.9kWkg−1, as well as superior cycling stability with 91.4% capacitance retention after 10,000 cycles. The results indicate that the Cr2O3 nanoplates embedded in carbon matrix show promising potential to construct high-performance energy storage devices.

Effect of Pesticides on Bacterial and Fungal Populations in Ecuadorian Tomato Cultivated Soils

Indiscriminate use of insecticides and fungicides leads to a combined contamination of pesticide residues in the soil environment and causes a severe threat to beneficial microbial activities. Hence, it is essential to assess the microbial populations of soils in the biosphere. In this study, two insecticides, cypermethrin and chlorpyrifos alone and in combination with two fungicides, mancozeb and carbendazim, were assessed for their effects on the bacterial and fungal populations in two tomato cultivated soils. Samples of soil-1 and soil-2 were collected from tomato cultivated fields of El Quienchi, Pichincha, Ecuador. Initially the physico-chemical characteristics of soils, e.g., soil pH, organic matter, total nitrogen, electrical conductivity, sand, silt and clay contents were detected, and then soil bacterial and fungal populations were determined. The influence of selected pesticides alone or in combination on the bacterial and fungal population was concentration-dependent; the populations were increased with increasing concentration of pesticides up to 5.0 kg ha−1 compared to the controls in 10-day incubated soils. The bacterial and fungal populations continued to increase up to 20 days, and then, gradually decreased after 30 and 40 days of incubation. The results clearly indicate that application of individual and/or mixtures of the pesticides in cultivation of tomato, at field application rates (2.5–5.0 kg ha−1), significantly improved the bacterial and fungal populations in soil-1 and soil-2. However, further increase in the dose of pesticides (7.5–10 kg ha−1) dramatically decreased the bacterial and fungal populations. On the other hand, insecticides in combination with fungicides showed negative effect on fungal populations.

Electrical conductivity and magnetic field dependent current-voltage characteristics of nanocrystalline nickel ferrite

We have studied the grain size dependent electrical conductivity, dielectric relaxation and magnetic field dependent current voltage (I−V) characteristics of nickel ferrite (NiFe2O4). The material has been synthesized by sol-gel self-combustion technique, followed by ball milling at room temperature in air environment to control the grain size. The material has been characterized using X-ray diffraction (refined with MAUD software analysis) and Transmission electron microscopy. Impedance spectroscopy and I−V characteristics in the presence of variable magnetic fields have confirmed the increase of resistivity for the fine powdered samples (grain size 5.17±0.6nm), resulted from ball milling of the chemical routed sample. Activation energy of the material for electrical charge hopping process has increased with the decrease of grain size by mechanical milling of chemical routed sample. The I−V curves showed many highly non-linear and irreversible electrical features, e.g., I−V loop and bi-stable electronic states (low resistance state-LRS and high resistance state-HRS) on cycling the electrical bias voltage direction during I-V curve measurement. The electrical dc resistance for the chemically routed (without milled) sample in HRS (∼3.4876×104Ω) at 20V in presence of magnetic field 10kOe has enhanced to ∼3.4152×105Ω for the 10h milled sample. The samples exhibited an unusual negative differential resistance (NDR) effect that gradually decreased on decreasing the grain size of the material. The magneto-resistance of the samples at room temperature has been found substantially large (∼25–65%). The control of electrical charge transport properties under magnetic field, as observed in the present ferrimagnetic material, indicate the magneto-electric coupling in the materials and the results could be useful in spintronics applications.

電気しゅう動接点におけるライダ表面に設けた溝が通電および摩擦特性に及ぼす影響に関する実験的解析

電気しゅう動接点におけるライダ表面に設けた溝が通電および摩擦特性に及ぼす影響に関する実験的解析

Electronic and Electrical Conductivity of AB and AA-Stacked Bilayer Graphene with Tunable Layer Separation

This humble work attempts to study the electronic and electrical conductivity characteristics of AB and AAstacked bilayer graphene (BLG) sheet, by using ab initio calculation. The electronic transport coefficient was calculated by using Boltzmann transport equations implanted in Boltztrap package at various temperatures from 80 to 380 K. First, this study will begin to experiment an interlayer spacing from 3.55 and 3.35 A respectively for AA and AB-BLG. If the distance between the layers is more than 5.00 A, the increase or decrease of energy does depend on the interlayer spacing so band gap is equal to zero. The electrical conductivity of AA and AB-BLG is compared to the experimental electrical conductivity of graphene monolayer under increasing spacing between layers to 4.00 A. Band gap decreases with the increasing space while conductivity increases with increasing space. AA-BLG electrical conductivity shows a value near to the experimental electrical conductivity of graphene ribbon for 4.00 A at 380 K. Nevertheless, the distance variation does not much affect the electronic and electrical characteristics of AB-BLG. In addition, the increase between the interlayer distances does not influence so much the electrical conductivity. Therefore, increasing the distance between interlayers decreases the electrical conductivity due to the increasing of band gap.

The Film Thickness Effect on Electrical Conduction Mechanisms and Characteristics of the Ni–Cr Thin Film Resistor

The electrical conduction mechanisms of Ni–Cr thin film resistor are demonstrated by different film thickness through scattering models fitting. The resistivity and temperature coefficient of the resistance of Ni–Cr thin film are measured to investigate the influence of thickness with different annealing temperature. Finally, an oxidation and atom inter-diffusion model was proposed to explain the effects of film thickness on the electrical properties of Ni–Cr thin film resistor under different annealing temperature.

Electrical Conduction Characteristics of Low Density Polyethylene and Cross Linked Polyethylene Nanocomposite for High Voltage Direct Current Power Cable

Electrical Conduction Characteristics of Low Density Polyethylene and Cross Linked Polyethylene Nanocomposite for High Voltage Direct Current Power Cable

The electric conductivity characteristics of seawater ionic solution under the influence of magnetic field

The electric conductivity of magnetized and unmagnetized seawater ionic solutions was measured by impedance analyzer (4294A, Agilent Technologies) at 12[Formula: see text]C, 1 KHz. A new relationship model of conductivity and concentration has been established, which fitted both magnetized and unmagnetized samples and was suitable for all the solutions whether at low concentration or at high concentration. Meanwhile, it was found that the magnetic field effect on the conductivity of solution is to some extent due to the changes of thickness and order of water shell around the ion.

Inkjet Printing of Graphene Inks for Wearable Electronic Applications

Inkjet printing of graphene-based conductive inks is an encouraging research approach in the field of printed electronics as both the benefits of inkjet printing and extraordinary electronic, optical and mechanical properties of graphene can be exploited [1]. Inkjet printing is one of the most promising techniques for the fabrication of wearable electronics due to number of advantages over conventional manufacturing techniques such as digital and additive patterning, reduction in material waste, deposition of controlled amount of materials and compatibility with various substrates [2]. In addition, graphene is a single atom thick two-dimensional closely packed honeycomb lattice of sp2 carbon allotropes, which has been focus of mass investigations in recent years because of its unique physical and chemical properties [3].Currently silver nanoparticles (NPs) as inkjet printing inks are the most reported and utilised conductive inks because of their excellent electrical conductivity and strong antioxidant characteristics [4]. However higher concentration of NPs and higher sintering temperatures are required in order to obtain continuous metallic phase, with numerous percolation paths between metal particles within the printed pattern [5], which increased processing cost and limited the choice of substrates to be printed because of their heat sensitivity. Inkjet printing of reduced graphene oxide (rGO) are reported in several studies as a popular choice to fabricate wearable devices due its advantages such as readily dispersible in water and high volume production at lower cost [6]. However large number of unreduced oxygen-containing functional groups and inter-sheet junctions between the graphene domains limits the conductivity achieved with rGO [7]. In order to overcome the limitations associated with rGO inkjet inks, pristine graphene inks were developed and printed.Herein we report exfoliation of pristine graphene dispersions produced in gram scale quantities based on literature review [8, 9]. Liquid phase exfoliation method was used by shear mixing in the presence of a polymer stabilizer, ethyl cellulose which enhances the ink stability as well as printing performance [2, 10]. To formulate ink for inkjet printing graphene/ethyl cellulose powder was directly dispersed in a mixture of solvents by bath sonication. Then the formulated inks were successfully inkjet printed onto textile substrate in order to fabricate an Electro-Oculogram (EOG) device for healthcare applications, Figure 1. &lt;fig position="float" id="s121_f.1"&gt; &lt;label&gt;Figure 1&lt;/label&gt; &lt;caption&gt;Graphene printed electrodes on textile substrates for bio-sensing without requiring a fixed connection to the body&lt;/caption&gt; &lt;graphic mime-subtype="tif" xlink:href="Images\s121_f01.tif" xmlns:xlink="http://www.w3.org/1999/xlink"/&gt; &lt;/fig&gt