Specific Electrical Conductivity Research Articles

A Note on Conservative Mixing: Implications for Selecting Salinity-Transport Model Constituents in the San Francisco Estuary

The deviation of specific electrical conductance (EC) from conservative mixing behavior is well-established in the scientific literature. This principle is based on the observation that, as salt concentration in a water sample increases, the mobility of individual ions in the sample decreases, and thus their ability to conduct electricity decreases. Despite this fact, some commonly used models for salinity transport in the San Francisco Estuary (estuary) utilize EC as a primary simulation constituent, treating it as a conservative quantity. Such a modeling approach has likely been followed to exploit the wide availability of EC data for model calibration and validation, and to obviate the need to translate between EC and salinity in a domain characterized by multiple source waters with varying ionic make-ups. Arguably, this approach provides a reasonable trade-off between data translation error and model simulation error. In this paper, we critically evaluate this approach, employing an extensive salinity data set that includes measurements of EC and major ion concentrations in the estuary. We demonstrate and quantify EC deviation from steady-state, conservative mixing behavior; review the conservative mixing behavior of three bulk salinity measures (practical salinity, ionic strength, and limiting equivalent conductance); and evaluate their source-dependent correlations with EC in the estuary. We find limiting equivalent conductance—a value that assumes uninhibited mobility among individual ions in a water sample—to be an attractive alternative for salinity transport in the estuary. In addition to being a conservative quantity, it is consistently correlated with EC in the estuary’s dominant source waters, and thus addresses concerns related to data-translation error. We conclude this paper discussing pros and cons of adopting various salinity-transport model constituents.

Revealing the Electrochemistry of All-Solid-State Li-SeS2 Battery via Transmission Electron Microscopy

Li-SeS2 batteries balance the opposing and complimentary qualities of Li-S and Li-Se batteries by having a high specific capacity and high electrical conductivity. However, there is still a lack of knowledge regarding the electrochemical characteristics of Li-SeS2 all-solid-state batteries (ASSB). Herein, transmission electron microscopy (TEM) is used to reveal the electrochemistry of a Li-SeS2 battery. It is discovered that, without the Polyethylene glycol (PEG), amorphous SeS2 in Li-SeS2 ASSB change into crystalline selenium and a small amount of sulfur. The continuous loss of sulfur from the active material may be related to the failure of the cell at 15 cycles and the severe instability of the Coulombic efficiency. It was found that the PEG coating selenium disulfide graphene composite (PEG@rGO-SeS2) cathode maintained a specific capacity of 258 mAh g−1 and a stable Coulombic efficiency of about 97% after 50 cycles. TEM analysis shows that the charging product remains as a granular amorphous selenium disulfide with a constant Se/S ratio during cycling. The PEG-protected selenium disulfide can effectively limit the loss of elemental sulfur and regulate the reaction mechanism of the Li-SeS2 batteries.

Composition engineering strategy of carbon–coated bimetallic phosphide for high energy density hybrid supercapacitors

Bimetallic phosphides hold great promise for using in hybrid supercapacitors (HSCs) as electrode material due to their synergistic effect of hetero-metal ions in ameliorating specific capacity and electrical conductivity. The production of bimetallic Ni1-xCoxP nanocrystals based on carbon-coated (Ni1-xCoxP@C) is described, and their potential application as positive electrodes in HSCs is also discussed. We give an insight into the significance of composition engineering for nickel-cobalt bimetallic phosphides in obtaining excellent electrochemical performance for supercapacitors. Ni0.9Co0.1P@C electrode reaches a maxima specific capacity as high as 4250 ± 48 mC cm−2 at 1 mA cm−2 (1327 ± 15 C g−1 at 1 A g−1), outperforming most transition metal phosphides (TMP)-based electrodes reported recently. Utilizing Ni0.9Co0.1P@C as electrode, the obtained HSC device provides a desired energy density of 46.9 ± 2.2 Wh kg−1 at 1600 W kg−1 and continues to sustain 26.2 ± 1.3 Wh kg−1 at a significant power density of 8000 W kg−1, capacitance retention remaining at 89.4 % after 10,000 cycles. It is believed that the Ni0.9Co0.1P@C has significant promise for application in extremely effective and affordable HSCs, as well as probably in other energy storage devices.

Application of the practical salinity scale to the waters of San Francisco estuary

The Practical Salinity Scale 1978 (PSS-78)—developed using samples of standard seawater—is widely used as a conductivity-based measure of salinity in oceans and estuaries. Here we evaluate the application of the scale across San Francisco Estuary where salinity reflects a mixture of seawater, riverine inflows, and agricultural return flows from islands within the estuary. We employ an extensive salinity data set that includes measurements of specific electrical conductance (EC) and major ion concentrations to demonstrate the scale's applicability in this estuary. We find the scale to be valid in waters dominated by seawater intrusion as well as in waters dominated by the largest riverine input to the estuary, i.e. the Sacramento River. In these waters, we further find that the scale to be valid well below its recommended lower-bound value of 2.0. However, the scale under-estimates salinity in waters dominated by the San Joaquin River, the second largest riverine input to the estuary. Similarly, the scale under-estimates salinity in agricultural return flows to the estuary. This work shows that a singular PSS-78 relationship cannot be used to accurately compute salinity across the entire estuary from EC measurements—a finding of considerable importance for salinity monitoring and modeling applications. Using data from the estuary, we propose appropriate corrections to the scale for these drainage-influenced waters. We recommend further research into how these modified PSS-78 formulations can be used to more accurately estimate salinity and ionic constituent concentrations in this and other estuaries.

Ensuring the supply of current to one end of the cable with different wire rope parameters

Issues. Structural cable monitoring systems are widely used to diagnose the condition of cable-stayed bridges. Known methods of non-destructive control of the stressed state cannot in some cases be fully used, or their use is difficult and economically impractical or inefficient. The aim of the study. A model is offered that allows you to ensure the reliability of the rope with many degrees of damage. Method. The most convenient method for monitoring the mechanical parameters of cable ropes is the electrical resistance method. The results. The results of the dependence of the stress and current distribution on the rope parameters are presented. The researched method will increase the reliability, safety and service life of cable-stayed bridges. Scientific novelty. Our work consists in studying the impact of breaking the cables that make up cable ropes. For this, a model was created that allows you to combine several parameters (specific resistance and electrical conductivity, length, number of cables). We considered the case for removing the signal from one end of the cable. Practical significance. It is established that when changing the length of the resistance application and the number of cables, a change in the graph for the undamaged and damaged cable is displayed. The number and row in which the burst occurred were analyzed. In this way, the system that monitors one cable notifies about destruction and makes it possible to prevent it.

Electrical Conductivity and Molar Volume of (LiCl-KCl)eut.–CsCl Molten Mixtures

The electrical conductivity of (LiCl-KCl)eut.–CsCl molten mixtures has been measured over a concentration range of 0–100 mol % CsCl and in a wide temperature span (624–1180 K). The measurements were carried out in quartz cells of the capillary type with platinum electrodes using the AC-bridge method. The molar volume of these mixtures was estimated using similar literature data. The maximum deviations of the molar volume from the additive values are ∼2%. Molar conductivity and its activation energy were calculated using the derived molar volume data. It was found that the electrical conductivity of all melts increases with increasing temperature and decreases with increasing CsCl concentration. In the molten (LiCl-KCl)eut.–CsCl mixtures, the significant negative deviations of the specific and molar electrical conductivities from additive values are observed over the whole concentration range, which indicates that the replacement of one alkaline cation by those, significantly different in size, is accompanied by a noticeable rearrangement of interparticle bonds. Therefore, the complexation in the system becomes different. According to the obtained data on electrical conductivity, the liquidus line of this system was built.

Single-Walled Carbon Nanotube/Copper Core-Shell Fibers with a High Specific Electrical Conductivity.

Carbon nanotube (CNT)/Cu core-shell fibers are a promising material for lightweight conductors due to their higher conductivity than pure CNT fibers and lower density than traditional Cu wires. However, the electrical properties of the hybrid fiber have been unsatisfactory, mainly because of the weak CNT-Cu interfacial interaction. Here we report the fabrication of a single-walled CNT (SWCNT)/Cu core-shell fiber that outperforms commercial Cu wires in terms of specific electrical conductivity and current carrying capacity. A dense and uniform Cu shell was coated on the surface of wet-spun SWCNT fibers using a combination of magnetron sputtering and electrochemical deposition. Our SWCNT/Cu core-shell fibers had an ultrahigh specific electrical conductivity of (1.01 ± 0.04) × 104 S m2 kg-1, 56% higher than Cu. Experimental and simulation results show that oxygen-containing functional groups on the surface of a wet-spun SWCNT fiber interact with the sputtered Cu atoms to produce strong bonding. Our hybrid fiber preserved its integrity and conductivity well after more than 5000 bending cycles. Furthermore, the current carrying capacity of the coaxial fiber reached 3.14 × 105 A cm-2, three times that of commercial Cu wires.

Influence of Heterogeneous Ion-Exchange Membranes Composition on Their Structure and Transport Properties

The physicochemical properties of experimental heterogeneous MK-40 and MA-41 membranes with different ratios of ion-exchange resin and polyethylene binder in their composition are studied. It is shown that the specific electrical conductivity in 0.01–1 M NaCl solution decreases by more than 3 times for cation-exchange membranes and by 2 times for anion-exchange ones with a decrease in the content of ion-exchange resin in the membranes from 69 to 55%. It has been established that the diffusion permeability of anion-exchange membranes is more sensitive to their composition and naturally increases with an increase in the ion-exchange resin proportion in the composition. Information on the influence of the heterogeneous membrane composition on its structure, obtained by method of standard contact porosimetry, is supplemented by the calculation of transport-structural parameters of the microheterogeneous and extended three-wire models of the ion-exchange membrane.

Investigation of electrical conductivity based on porous hollow carbon black for EDLC

The crystallinity of carbon black nanoparticles is inhomogeneous, and therefore hollow type carbon black are prepared by selectively removing amorphous cores while maintaining aligned skins. Herein, we prepare hollow carbon nanoparticles composed of mesopores with good EDLC performance from commercial carbon black through an extremely mild oxidation method. Hollow type carbon black have improved specific surface area and an ion reservoir region can be formed due to their structural characteristics, making them suitable for EDLC electrodes. Carbon blacks, however, has different physical properties such as the specific surface and electrical conductivity. Exploiting these differences, we investigated the effect of surface area and electrical conductivity on EDLC performance.

Synthesis, structure, oxygen stoichiometry, and electrical properties of doped ruddlesden-popper strontium cobaltite Sr1·875Ce0·025CoO4-δ, Sr1·875Ce0·025Co0·75Ni0·25O4+δ novel compounds

We report the synthesis of Sr1·875Ce0·025CoO4-δ and Sr1·875Ce0·025Co0·75Ni0·25O4+δ for the first time, each compound was synthesised using Co-precipitation and Sol-Gel methods, at 1050 °C for 144 and 120 h respectively. Oxygen stoichiometry was determined using Iodometric titration, we have noticed oxygen hypostoichiometry for Ce-doped compound and hyperstoichiometry state after Ni-doping. Electrical properties were studied for sintered pellets, Electrical resistance was measured in the range (−0.5–+0.5 v). Specific electrical resistivity and electrical conductivity were calculated from resistance measurements. It was found that the Ce-doped compound has about three times higher conductivity (σC1 = 0.000000058423295 s cm−1) Compared with the Ni-doped one (σN2 = 0.000000022384787 s cm−1). Electrical Capacitance was measured at 1 kHz frequency, the relative dielectric constant εr, and the loss tangent tanδ were calculated accordingly. The results showed that the Ni-doped compound has higher capacitance but lower εr and dissipation factor values.

Production of high-strength weakly conductive ceramics based on barium aluminate

Weakly conductive ceramics based on barium aluminate have been synthesized and investigated. When fired in an oxidizing medium monophase ceramics with a maximum compressive strength of 678.5 MPa and a density of 3.78 g/cm3 were obtained. The introduction of conductive additives into the composition makes it possible to increase the specific electrical conductivity of ceramics to 1.05 · 10–4 S/cm (at 300°C).

Chemical Indication of the Processes of Freshet Runoff Formation in a Small Experimental Catchment in the Prilenskoe Plato, The Republic of Sakha (Yakutia)

The article considers the theory, methods, and some results of four-year field studies of the processes of runoff formation on a small freezing experimental river catchment in a continuous thick (400 m) permafrost zone (the Republic of Sakha (Yakutia)) based on data on natural water chemistry. The analyzed problems include the seasonal and daily dynamics of river flow in the warm season, the concentrations of some dissolved substances in different types of water, as well as the role of channel widenings, supra-permafrost water, and aufeises in flow formation. Various types of relationships between water discharges and the concentrations of some dissolved substances are described under varying hydrothermal conditions. The role of nonfreezing lake-like channel widenings (bochags) in the regulation of freshet flow of water and dissolved matter is evaluated. The efficiency of the automated digital registration of the level, temperature, and specific electric conductance of water with a high time resolution at hydrological gages is discussed, especially, as applied to the rapid processes in a river.

Increasing the accuracy of measuring the physicochemical parameters of wastewater samples when implementing a new informative method

Increasing the accuracy of measuring the physicochemical parameters of wastewater samples when implementing a new informative method

A Technique for Multi-Parameter Signal Processing of an Eddy-Current Probe for Measuring the Thickness of Non-Conductive Coatings on Non-Magnetic Electrically Conductive Base Metals

The known amplitude-sensitive eddy-current method for measuring the thickness of non-conductive coatings on conductive non-magnetic base metals does not satisfy the accuracy requirements. A primary consideration is the significant influence of a change in the specific electrical conductivity of the base metals on results of measurements. In this study, we developed a technique for measuring the thickness of non-conductive coatings on non-magnetic conductive base metals by using the eddy-current amplitude-phase method and implemented algorithms to process obtained information. Our method considered the influence of the specific electrical conductivity of the base metals by forming a two-dimensional graduation characteristic of the thickness gauge by using several base metals with different specific electrical conductivity. The algorithm for point-in-polygon determination was applied, which allowed us to measure the thickness of the coatings and the specific electrical conductivity of the base metals as independent values. The equipment necessary to construct the two-dimensional graduation characteristic and the algorithm for calculation of the thickness are described in detail.

Influence of random parameter joint length on rock electrical conductivity

Rock joint hollowness coefficient is an important parameter when resolving practical mining problems. Geophysical methods used to resolve this problem are indirect. Thus the interpretation of their results may cause certain difficulties as a result of the uncertainty of the physical relationships between the parameters of joints and the measurement results. One of the ways to resolve this problem is to combine experimental research methods with analytical and numerical simulation. The studies were aimed at investigating the electrical conductivity of a two-dimensional medium in the presence of thin insulating (non-conducting) joints. This paper proposes an analytical method for assessing the dependence of the specific conductivity of a medium with inclusions in the form of elliptical joints on their half-length. This dependence is show to have the form of an exponent depending on the square of the length of the maximum semi-axis as an argument. The simulation method is based on the assumption of the elliptical shape of a joint when the length of the minor semi-axis of the ellipses tends to zero. A review of publications and their results presented in this paper showed that this method for determining the specific conductivity of the medium with thin joints is one of the best in terms of compliance with experimental data. Its predictions are close to those of the Effective Media Approximation (EMA). However, the proposed method is distinguished by the simplicity of the formulas and their physical visibility essential for the use in interpreting the data of a physical experiment. In two-dimensional formulation, numerical simulation of the specific electrical conductivity of a sample of a medium measuring 1×1 m with elliptical joints of conductivity less than that of the matrix was carried out in the COMSOL Multiphysics environment. A square sample of unit sizes with unit conductivity was considered in which 25 joints with uniform distribution along the length occurred. 40 models were built wherein the maximum length of the joints varied from 0.01 to 0.4 sample size in increments of 0.01 m. The satisfactory concordance of the results of numerical and analytical models, both visual and confirmed by statistical estimates, has been shown. It was noted that when the size of the joints changes to achieve the value of the maximum semi-axis α = 0.15 m, the influence of single joints that do not extend beyond the boundaries of the sample prevails. Above this value, at α > of 0.15 m, the influence of joint coalescence, as well as their extension to and beyond the sample boundaries begins to affect. Comparison of the proposed theoretical model of electrical conductivity, depending on the square of the length of the maximum semi-axis of a joint, with a similar model in the form of an exponent with a linear dependence showed a better concordance of the proposed model with observations at the stage of the lack of joint coalescence and their extension to the sample boundaries at α < 0.15 m. At α > 0.15 m. The proposed model has a lower coefficient of determination compared to the full range including both intervals, but higher than that of the model with a linear dependence in the exponent argument. This indicates the universal nature of the proposed model.

On the thermoelectric alloy SixGe1-x

The temperature dependences of the electronic quality factor and universal electrical conductivity of the n-type SixGe1-x alloy, as well as the dependence of the Seebeck coefficient on the specific and universal electrical conductivities are studied. Based on the measured thermoelectric parameters (Seebeck and thermal conductivity coefficients, specific resistance) the values of thermoelectric efficiency Z are calculated. The temperature dependences of universal electrical conductivity shows that the experimental points form almost a single set. This is due to the fact that changes of σ and B_E compensate each other. And, in general, the electronic quality factor BE performs scaling of thermoelectric quantities. The temperature dependences of thermoelectric efficiency shown that all SixGe1-x samples have a fairly high efficiency (≥7∙10-4 grad-1), the maximum of which is reached at about 700℃. The studied alloy were used as an element of a monolithic thermoelectric module.

Possibilities of Physical-Chemical Sensors' Use for Optimizing the Processing of Metallurgical Melting Based on Computer Systems.

This article presents aspects regarding the possibilities of optimizing the quality of the elaboration of metallurgical melts by determining their physical-chemical properties. Thus, the article analyzes and presents methods for determining the viscosity and electrical conductivity related to metallurgical melts. Among the viscosity determination methods, two methods are presented, namely: the rotary viscometer method and the electro-vibratory viscometer method. Determining the electrical conductivity of a metallurgical melt is also of particular importance for ensuring the quality of the elaboration and refining of the melt. The article also presents the possibilities of using and implementing computer systems that ensure the accuracy of determining the physical-chemical properties of metallurgical melts, as well as examples of the use of physical-chemical sensors and specific computer systems for determining the analyzed parameters. The specific electrical conductivity measurements of oxide melts are performed by direct methods (by contact), with Ohm's law as a starting point. Thus, the article presents the voltmeter-ammeter method and the point method (or the zero method). The novelty of this article is the description and the use of specific methods and sensors for certain determinations (viscosity and electrical conductivity) for metallurgical melts. The motivation here is the presentation of the authors' research in the addressed field. The article presents an original contribution of the adaptation and use of some methods for determining some physico-chemical parameters, including specific sensors, in the field of the elaboration of metal alloys, with the aim of optimizing their quality.

ВЛИЯНИЕ ЭНЕРГОСОДЕРЖАНИЯ СОЕДИНЕНИЙ НЕОДИМА НА УДЕЛЬНУЮ ЭЛЕКТРОПРОВОДНОСТЬ КОБАЛЬТИТА НЕОДИМА

The influence of the genesis of neodymium cobaltite on its energy content and specific electrical conductivity has been established. The dependences of the specific electrical conductivity of neodymium cobaltite on its energy content, calculated according to X-ray diffraction analysis, and temperature are determined.

Vertically stacked heterostructures of MXene/rGO films with enhanced gradient impedance for high-performance microwave absorption

Owing to high specific surface area and electrical conductivity, 2D materials are widely used for microwave absorption to address the problems of electromagnetic wave pollution, which induced by the advancement of wearable electronic devices and 5G wireless communication. However, the major challenges arise from the unsatisfied dielectric loss capacity that seriously limits the application of 2D-based microwave absorber. Herein, a vertical heterostructure architecture was exploited to synthesize MXene/rGO films, which deliver different impedance gradients. In particular, the MrG film with 80 wt% rGO content exhibit excellent microwave absorption with a minimum reflection loss value of −44.3 dB at 7.06 GHz (＞99.99% of the electromagnetic wave is absorbed) and an effective absorption bandwidth of 4.84 GHz at a thickness of 1.5 mm. The enhanced dielectric loss capacity is attributed to vertically stacked heterostructures, providing new electron transport and leap channels along the vertical direction of the films. Moreover, visualized power loss density simulations are first used to investigate the evolution of the loss densities, further confirming the synergistic interaction between MXene and rGO can substantially increase microwave absorption. This finding provides an alternative approach for the developing efficient, customizable, simple, and low-cost 2D material-based absorbers through controlling formation of vertical heterostructures.

Fomes fomentarius as a Bio-Template for Heteroatom-Doped Carbon Fibers for Symmetrical Supercapacitors

Nowadays, commercial electric double-layer supercapacitors mainly use porous activated carbons due to their high specific surface area, electrical conductivity, and chemical stability. A feature of carbon materials is the possibility of obtaining them from renewable plant biomass. In this study, fungi (Fomes fomentarius) were used as a bio-template for the preparation of carbon fibers via a combination of thermochemical conversion approaches, including a general hydrothermal pre-carbonization step, as well as subsequent carbonization, physical, or chemical activation. The relationships between the preparation conditions and the structural and electrochemical properties of the obtained carbon materials were determined using SEM, TEM, EDAX, XPS, cyclic voltammetry, galvanostatic measurements, and EIS. It was shown that hydrothermal pretreatment in the presence of phosphoric acid ensured the complete removal of inorganic impurities of raw fungus hyphae, but at the same time, saved some heteroatoms, such as O, N, and P. Chemical activation using H3PO4 increased the amount of phosphorus in the carbon material and saved the natural fungus’s structure. The combination of a hierarchical pore structure with O, N, and P heteroatom doping made it possible to achieve good electrochemical properties (specific capacitance values of 220 F/g) and excellent stability after 25,000 charge/discharge cycles in a three-electrode cell. The electrochemical performance in both three- and two-electrode cells exceeded or was comparable to other biomass-derived porous carbons, making it a prospective candidate as an electrode material in symmetrical supercapacitors.