Electrical Conductivity Properties Research Articles

Microstructural, Electrical and Mechanical Properties of the Al-Zn-Mg-Mn Alloy with Strontium Addition

This study investigated the improvement in the electrical conductivity and mechanical properties obtained by adjusting the amount of the Sr addition to the Al-Zn-Mg-Mn alloy. The addition of Sr formed an intermetallic compounds, and the volume fraction of the intermetallic compounds increased with increasing Sr content. As the amount of Sr added increased from 0 to 1.0 wt%, the electrical conductivity of the extruded alloy decreased to 48.9, 45.2 and 42.5% IACS. As the addition amount of Sr increased, the average grain size of the rolled alloy decreased to 55.5, 53.1 and 42.3 μm. And, the ultimate tensile strength increased to 195, 212 and 216 MPa.

Self-Assembly Enabled Printable Asymmetric Self-Insulated Stretchable Conductor for Human Interface.

Soft and stretchable conductors with high electrical conductivity and tissue-like mechanical properties are crucial for both on-skin and implantable electronic devices. Liquid metal-based conductors hold great promise due to their metallic conductivity and minimal stiffness. However, the surface oxidation of liquid metal particles in polymeric matrices poses a challenge in forming a continuous pathway for highly conductive elastic composites. Here, it is reported a printable composite material based on liquid metal and conducting polymer that undergoes a self-assembly process, achieving high conductivity (2089 S cm-1) in the bottom surface while maintaining an insulated top surface, high stretchability (>800%), and a modulus akin to human skin tissue. This material is further applied to fabricate skin-interfaced strain sensors and electromyogram sensors through 3D printing.

High aspect ratio Na–Co-oxide ceramic filler composites with novel electrical and dielectric properties

Polymer composites with high aspect ratio Na–Co oxide ceramic filler – polymer matrix was investigated in this study. They demonstrate high dielectric permittivity, low dielectric loss tangent values which is useful for capacitive field grading and reversible voltage dependent electrical conductivity properties under an applied electric field which can be utilized for resistive field grading. These unique properties are useful for electrical stress control applications in power components. This study employs novel ceramic platelets as the varistor filler component in a polymer composite form, introducing a new class of materials to the world of electrical stress control technology. By minimizing the amount of varistor filler material required to very low levels (15 wt%), it is possible to develop lightweight non-linear dielectric composites that not only exhibit improved electrical characteristics but also make processing easier and open up new design space for making various components for electrical power applications. By utilizing novel NaxCoO2 (x < 1) ceramic fillers in composite form, we aim to contribute to the development of innovative nonlinear dielectric composites that can enhance the performance and processibility of various power system components under various working environments.

Improving mechanical property and corrosion resistance of high electrical conductivity Al-Ce-Sc-Y and Al-Mg-Si-Ce-Sc-Y alloys by laser shock peening

The high electrical conductivity Al-Ce-Sc-Y and Al-Mg-Si-Ce-Sc-Y alloys were used to study the effects of laser shock peening on their mechanical property, pitting and intergranular corrosion resistance. The strength and elongation of the alloys were improved simultaneously at the expense of very low electrical conductivity after laser shock peening due to the gradient structure and residual compressive stress. After two side laser shock peening, the strength and elongation of Al-Ce-Sc-Y and Al-Mg-Si-Ce-Sc-Y alloys increased to 231 ± 3 MPa/16.2 ± 0.2 % and 359 ± 3 MPa/17.1 ± 0.3 %, respectively. The samples with two surface states were used to study the corrosion behaviors. The number and depth of corrosion pits can be significantly reduced by laser shock peening and the crystallographic corrosion morphology exists in the corrosion pits. After two side laser shock peening with polished surface, the intergranular corrosion depth of Al-Mg-Si-Ce-Sc-Y alloy can reach the minimum and the intergranular corrosion cracks are much finer at the same depth. The Al-Ce-Sc-Y alloy had no tendency of intergranular corrosion, but the unpolished surface was prone to form the deep corrosion pits rather than occurred uniform corrosion. According to the microstructure analysis, the corrosion mechanism of pitting and intergranular corrosion was revealed.

Three-Water Differential Parallel Conductivity Saturation Model of Low-Permeability Tight Oil and Gas Reservoirs

Addressing the poor performance of existing logging saturation models in low-permeability tight sandstone reservoirs and the challenges in determining model parameters, this study investigates the pore structure and fluid occurrence state of such reservoirs through petrophysical experiments and digital rock visualization simulations. The aim is to uncover new insights into fluid occurrence state and electrical conduction properties and subsequently develop a low-permeability tight sandstone reservoir saturation model with easily determinable parameters. This model is suitable for practical oilfield exploration and development applications with high evaluation accuracy. The research findings reveal that such reservoirs comprise three types of formation water: strongly bound water, weakly bound water, and free water. These types are found in non-connected micropores, poorly connected mesopores where fluid flow occurs when the pressure differential exceeds the critical value, and well-connected macropores. Furthermore, the three types of formation water demonstrate variations in their electrical conduction contributions. By inversely solving rock electrical experiment data, it was determined that for a single sample, the overall cementation index is the highest, followed by the cementation index of pore throats containing strongly bound water, and the lowest for the pore throats with free water. Building on the aforementioned insights, this study develops a parallel electrical pore cementation index term, ϕm′, to account for the differences among the three types of water and introduces a parallel electrical saturation model suitable for logging evaluation of low-permeability tight oil and gas reservoirs. This model demonstrated positive application effects in the logging evaluation of low-permeability tight gas reservoirs in a specific basin in the Chinese offshore area, thereby confirming the advantages of its application.

The performance of partially substituted composite ester materials with weathered red-bed soil in ecological restoration.

Ester materials have become a significant topic in ecological restoration because of their degradability and lack of pollution. However, these artificial materials have issues such as high resource consumption and high cost. Therefore, finding a scientific substitute for ester materials is crucial to reduce costs. This study proposes the use of weathered red-bed soil to partially replace ester materials. Orthogonal coupled compounding and ecological effect tests were performed to analyze the soil improvement mechanism based on the mineral composition, soil structure, and electrical conductivity properties of the weathered red-bed soil. The experimental findings indicated that the soil modified using ester materials exhibited improved strength, water retention, and aeration owing to changes in the soil structure. Plant germination and height increased by 55% and 37 mm, respectively, when using a ratio of 15 g/m2 absorbent ester material, 2.5 g/m2 adhesive ester material, and 5% weathered red-bed soil. Through this approach, the amount of ester material to be used could be further reduced by 75%. The weathered red-bed soil offers improved ecological effects by altering the physical, mechanical, and hydraulic properties of the soil structure. This study presents a theoretical foundation for ecological conservation using weathered red-bed soil as a substitute for certain ester materials.

Unveiling the non-innocence of vanadium dopant in TiO2 nanocrystals for advanced energy storage and smart windows

Vanadium doped TiO2 NCs stand out as a promising candidate for energy storage applications due to its high electrical conductivity and redox properties. However, the thermodynamical behavior of the material under working conditions has not been explored and the reasons for its superior performance remain unlocked. This study explores the use of a combination of advanced in situ spectroscopy techniques, including x-ray absorption spectroscopy (XAS), spectro-electrochemistry (SEC), and electrochemical impedance spectroscopy (EIS) to provide unprecedented insights into the intricate electrochemical reaction mechanisms within these nanocrystals. Density functional theory calculations and EIS reveal the active role of substitutional V ions in the TiO2 anatase network as electron donors, enhancing surface charge and carrier density and improving pseudocapacitive properties. Cyclic voltammetry and in situ SEC reveal that V-doped TiO2 NCs exhibit significantly improved charge storage capacities, particularly in the pseudo-capacitance storage mechanism. In situ SEC and XAS analyses indicate that a more effective reduction of Ti4+ ions occurs during the electrochemical process in doped NCs, leading to higher charge capacitance and faster processes. Furthermore, in situ XAS measurements of the V K-edge revealed that the vanadium ions, beyond improving the redox behavior of the host, also actively participate in the reduction process. The significant changes in the V K-edge XANES and extended x-ray absorption fine structure spectra observed under reduction conditions can be ascribed to a change in the structure and oxidation state of the vanadium ions during the electrochemical reaction.

Transport coefficients of warm dense matter from Kohn-Sham density functional theory

Transport coefficients of warm dense matter from Kohn-Sham density functional theory

Effect of conductive surface-coated polyethylene fiber on the electrical and mechanical properties of high-performance fiber-reinforced cementitious composites

This study investigated the electrical conductivity and mechanical properties of high-performance fiber-reinforced cementitious composites (HPFRCC) with conductive coated ultra-high-molecular-weight (UHMW) polyethylene (PE) fibers. The silver nanoparticles with spherical shape were coated most evenly. Despite some parts of the fiber surface being less coated with carbon nanotube (CNT) and graphite nanofiber (GNF) compared to the silver nanoparticles, they effectively increased electrical conductivity of the plain PE fiber. Both the coating degree and conductivity of the coating material affect the conductivity of PE fiber. The compressive strength of HPFRCC was not affected by conductive coating. The electrical conductivity of HPFRCC improved by 18.7%–45.1% than the control specimen, and the highest electrical conductivity was achieved when coated with silver nanoparticles. Incorporating conductive coating fibers had a negative effect on tensile strengths (18.9–23.5% decreases) but a positive effect on the ductility. The GNF-coated PE fibers led to the strain capacity and energy absorption capacity improved by 69.4 and 44.8%, respectively. Therefore, given the increase in deformation performance outweighs the decrease in tensile strength, engineered, conductive coating fibers can be used as novel reinforcement in HPFRCC to attain additional functionalities related to electrical capabilities.

Investigation of mechanical properties of graphene-CNT reinforced nickel metal matrix nanocomposite structure

Nickel is a metal widely used in many industrial applications, but despite its superior properties, it also has some shortcomings. Carbon-based structures can be important reinforcement elements in improving the properties of metals. By providing a balance between the high corrosion resistance, high electrical conductivity and good magnetic properties of the nickel material and the lightness and high strength of carbon-based structures, a material with advanced properties can be obtained. Therefore, in this study, a new Nickel-Carbon nanostructure supported by a covalently bonded graphene-carbon nanotube (CNT) skeleton structure is presented. Additionally, three material designs with different geometric dimensions (Ni-G-CNT(5,5), Ni-G-CNT(10,10) and Ni-G-CNT(15,15)) were designed to determine the mechanical properties and properties of the structures in all directions. is to investigate the underlying deformation mechanisms. According to the results, it was observed that G-CNT structures increased the tensile and compressive behavior of the Ni structure in the CNT direction. For tensile loading in the CNT direction, as the CNT diameter decreases, the elastic modulus of the hybrid structures increases, while the maximum stress values are independent of the CNT diameter. As the CNT diameter increases, the ductility of the structures increases. In terms of compressive strength, it has been observed that in the linear region, as the CNT diameter increases, the strength generally increases and in the condensation region, it exhibits better compressive strength. With this study, an anisotropic nanostructure that is lighter and can exhibit higher tensile strength compared to the Ni structure is presented.

Investigating the physical and optoelectronic characteristics of Co2ZrZ compounds: findings from computational analysis and thermoelectric evaluation.

The study examines the physical characteristics of Co2ZrZ compounds using the Wien2k code and the Anisimov and Gunnarsson approach. Results show metallic attributes in Co2ZrBi and Co2ZrAs, while Co2ZrPb exhibits semi-metallic tendencies. Energy gap evaluations reveal significant infrared transitions, indicating altered electron mobility compensated by increased ultraviolet absorption. These compounds have potential in space solar energy applications due to UV light absorption capabilities, especially in Co2ZrPb. The study also identifies optical phenomena like "super-luminescence" and plasmatic oscillations. The study uses computational techniques like Wien2k calculation code and Hubbard parameter calculations to investigate Co2ZrPb, a compound with potential for space energy applications. Energy gap assessments are conducted using GGA and mBJ-GGA methods. The study also analyzes the optical behavior of the compounds, including infrared and ultraviolet absorption. The BoltzTraP code is used for thermoelectric investigations, revealing a P-type charge carrier predominance in Co2ZrPb. This comprehensive approach provides valuable insights into electrical conductivity and thermoelectric properties.

In‐depth investigation and industry plan for enhancing surface finishing of 3D printed polymer composite components: A critical review

AbstractAdditive manufacturing (AM) is pivotal in modern manufacturing, allowing diverse materials to create functional parts. Polymer composites, with superior properties like enhanced mechanics and conductivity, are highly regarded. Fused deposition modeling (FDM) is a favored, cost‐effective AM technique. Despite popularity, FDM struggles with poor surface quality, impacting final part properties. This challenge affects composite part performance, prompting a need for surface quality enhancements in AM processes, like FDM. The review explores essential post‐treatments required to optimize composite parts for various applications. It examines surface finishing techniques for FDM 3D printed polymeric composites, categorizing them into chemical, thermal, and physical methods. Recent research is extensively analyzed, offering a comprehensive guide for academia and industry. The review covers diverse aspects, including properties, surface morphology, electrical conductivity, and mechanical properties pre‐ and post‐finishing methods. Additionally, it summarizes leading companies worldwide providing surface finishing services for 3D printed polymer parts. Discussions on future trends, challenges, and research gaps in this field are included, emphasizing its significance in refining surface finishing methods for FDM 3D‐printed polymeric composites and encouraging broader industrial adoption of AM. This overview serves as a crucial roadmap for engineers, scientists, customers, and companies interested in surface finishing services.

Volume exclusion effect and ambient temperature induced ultrahigh electromagnetic wave absorption properties of polylactic acid (PLA)/graphene nano‐platelets (GNPs) composites

AbstractConductive polymer composites (CPCs) have an excellent performance in dealing with electromagnetic (EM) radiation. The distribution of conductive fillers in CPCs plays a vital role in the electrical conductivity and EM wave‐absorbing properties. Moreover, the distribution evolution of GNPs in the PLA matrix caused by the enhanced volume exclusion effect via annealing was investigated. Polylactic acid with 8 wt.% graphene nano‐platelets (PG8) achieved best performance among the composites. After 5‐min heat treatment, the electrical conductivity and EM wave absorption properties of PLA/GNPs composites are significantly improved. With a simple treatment, the composite can reach an ultrahigh reflection loss (RL) value of −28.5 dB with a thickness of only 2.5 mm. By controlling the thickness in the range of 1–4 mm, the effective absorption bandwidth can be adjusted within 5.1–8.0 GHz. These methods provided in this work can effectively improve the EM wave absorption performance of CPCs and are worthy of being promoted.

Optimizing Performance in Supercapacitors through Surface Decoration of Bismuth Nanosheets.

Bismuth (Bi) exhibits a high theoretical capacity, excellent electrical conductivity properties, and remarkable interlayer spacing, making it an ideal electrode material for supercapacitors. However, during the charge and discharge processes, Bi is prone to volume expansion and pulverization, resulting in a decline in the capacitance. Deposition of a nonmetal on its surface is considered an effective way to modulate its morphology and electronic structure. Herein, we employed the chemical vapor deposition technique to fabricate Se-decorated Bi nanosheets on a nickel foam (NF) substrate. Various characterizations indicated that the deposition of Se on Bi nanosheets regulated their surface morphology and chemical state, while sustaining their pristine phase structure. Electrochemical tests demonstrated that Se-decorated Bi nanosheets exhibited a 51.1% improvement in capacity compared with pristine Bi nanosheets (1313 F/g compared to 869 F/g at a current density of 5 A/g). The energy density of the active material in an assembled asymmetric supercapacitor could reach 151.2 Wh/kg at a power density of 800 W/kg. These findings suggest that Se decoration is a promising strategy to enhance the capacity of the Bi nanosheets.

Low percolation threshold polyvinylidene fluoride/multi‐walled carbon nanotube composites: A perspective of electrical conductivity, crystalline, rheological and mechanical properties

AbstractRecently, conductive polymer‐based composites (CPC) have gained considerable interest for their outstanding processing, mechanical, electrical properties, and resistance tunability. Multi‐walled carbon nanotube (MWCNT) was introduced into polyvinylidene fluoride (PVDF) as the conductive filler via means of melt blending in this work. Effects of MWCNT on crystalline structure, thermodynamic behavior, electrical conductivity, processing and mechanical properties of PVDF/MWCNT were under investigation. By measuring the volume resistivity of PVDF/MWCNT, it was observed to have declined from 1.54 × 1012 to 3.71 × 101 Ω∙m with the MWCNT content changed from 0.7 to 1 vol%, which plummeted by 11 orders of magnitude. Therefore, it can be inferred that the percolation threshold of MWCNT lies within the range of 0.7–1 vol%. Additionally, the percolation threshold is obtained as 0.81 vol% by fitting using the percolation theory equation. Around the percolation threshold, PVDF/MWCNT composites exhibit negligible alterations in their rheological properties when contrasted with pure PVDF, yet their mechanical properties are improved. Furthermore, MWCNT does not substantially impact the crystalline structure and thermodynamic behavior of PVDF/MWCNT.Highlights The percolation threshold of MWCNT in PVDF is 0.81 vol%. The volume resistivity of the 1 vol% MWCNT sample was only 3.71 Ω∙m. 1 vol% MWCNT exhibit favorable rheological and mechanical properties.

Preparation, structural characterization, optical, photoluminescence, AC electrical conductivity and broadband dielectric properties of WO3 reinforced PEG/CS blend for futuristic optoelectronic and energy storage devices

Polymer nanocomposites (PNCs) composed of biopolymers and metallic oxides are important classes of materials. In addition to the environmental and economic considerations, these materials became the best candidates for various industrial fields. In the current study, solution cast procedure is used to prepare polymer nanocomposites (PNCs) based on polyethylene glycol (PEG)/chitosan (CS) blend and varying concentrations of tungsten trioxide nanoparticles (WO3 NPs), as a nanofiller. TEM micrograph shows that WO3 NPs have particle sizes of 5–32 nm their shapes are cubic and spherical. The XRD results reveal the semicrystalline of PEG/CS blend through showing three distinct diffraction peaks at 2θ = 7.42°, 19.47° and 23.62° and the degree of crystallinity is decreased after the incorporation of WO3 NPs due to the formation of polymer-nanoparticle interactions as indicated by FTIR spectra. The values of optical energy bandgap (direct and indirect) reduce while the Urbach energy increases with raising the concentration of WO3 NPs in the PEG/CS matrix. The PEG/CS-WO3 films' PL spectra show a photoemission peak at about 387 nm, where this peak loses intensity and becomes broader due to the induced defects and increase of disordering within the nanocomposite films. Additionally, the results of the dielectric investigation show an increase in the dielectric constant, dielectric loss, and AC electrical conductivity, which may be a sign of an increase of charge carriers and the content of amorphous regions that assists the movement of charge carriers. The DC electrical conductivity and conduction mechanism are also reported. Argand plot shows a half semicircle implying the Debye-type relaxation mechanism. The experimental results suggest the use of PEG/CS-WO3 nanocomposites as a possible contender for futuristic energy storage and optoelectronic applications.

Multifunctional flexible strain sensor based on three‐dimensional core‐shell structures of silver nanoparticles/natural rubber

AbstractConventional wearables may pose a health risk by promoting the growth of bacteria on the skin's surface due to sweating or contamination. Here, a multifunctional strain‐sensing composite has been fabricated through the combination of highly elastic natural rubber (NR) with silver nanoparticles (AgNPs), which possess antimicrobial and electrical conductivity properties. A 3D core‐shell structure composed of AgNPs and NR microspheres effectively reduces the percolation threshold of the AgNPs conductive network. As a strain sensor, the composite film presents a wide sensing range (0%–970%), an exceptionally high gauge factor (GF) value (59.3), and favorable cycling stability (over 1500 cycles at 50%). Finally, the composite film also exhibits antibacterial and hydrophobic properties, indicating its potential for use in challenging environments.

Precipitation behavior and electrical conductivity and mechanical properties of Cu-0.9Be-1.5Ni-0.04Y alloy

The optimum solid solution and aging processes for Cu-0.9Be-1.5Ni-0.04Y alloys, as well as the microstructure and strengthening mechanisms during aging were investigated. The results show that the optimum solid solution and aging temperatures are 980℃ and 480℃, respectively. During aging treatment at 480°C, the precipitation sequence of the Cu-0.9Be-1.5Ni-0.04Y alloy was supersaturated α solid solution → GP zone → γ″ phase → γ′ phase → γ phase. As increasing the aging time, the microhardness and yield strength of the alloy showed a trend of increasing and then decreasing, with the maximum of 220.9 HV and 626 MPa, respectively. The strengthening mechanisms of the nanoscale γ" and γ' phases in Cu-0.9Be-1.5Ni-0.04Y alloy were the shear mechanism and orowan mechanism, respectively. The electrical conductivity of the alloy increased and then remained more or less constant with increasing aging time, with a maximum of 39.78%IACS. The difference between the theoretical and measured values of the electrical conductivity of the alloy after aging at 480℃ for different times was less than 1%.

The conductivity effect of the top coating on optical properties of thin Cu(Ag)-layered structures

This study examines the optical properties of thin Cu (Ag)-layered structures covered with protective layers based on graphene, titanium (TiO2), or aluminium (Al2O3) oxides. The objective is to investigate the impact of these coatings on the optical behaviors of underlying metallic layers, specifically in the spectral range of excitation of surface plasmon resonances. Combining the methods of spectroreflectometry and spectro-ellipsometry was used to analyze the optical characteristics of the hybrid metal-oxide-graphene films. The study shows that graphene, due to its exceptional electrical conductivity and unique optoelectronic properties, significantly modifies the optical behavior of investigated structures. It includes notable changes in refractive and absorption indices, and optical conductivity indicating potential for enhancing light-matter interactions in plasmonic-graphene layered structures with the aim to apply as biosensor. It is important that addition of TiO2 and Al2O3 layers has also strong effects on the optical properties, which are relevant to their respective applications in the fields of optoelectronics and microelectronics. Employing the effective medium approximation and the Tauc–Lorentz model promotes deeper understanding the interplay between interband and intraband electronic transitions at the nanoscale level. It was revealed that the layer thickness of constituted materials and their individual dielectric functions together with addition of a graphene monolayer commit the significance for altering the optical properties of hybrid layered structures. The obtained results are important for the fields of plasmonics and nanotechnology, providing insights for designing sensors and devices with improved optical characteristics.

Dynamics of changes in the temperature coefficient of electrical conductivity of distilled water in conductometric cells during heating and cooling

The problem of taking into account the influence of air on the properties of distilled water is considered, namely the lack of a single generally accepted method for calculating such an influence. The sensitivity of the structure of water to the influence of external factors is described and the possibility of recording and studying such factors by changes in the temperature coefficient of electrical conductivity of water is shown. The dependences of the temperature coefficient of electrical conductivity of distilled water on the rate of change in water temperature, the degree of filling of conductometric cells, as well as on the intensity of the exchange of carbon dioxide between water and air across their interface have been studied. It is noted that these metabolic processes are currently insufficiently studied. A hardware-software measuring complex has been developed and manufactured to study the temperature coefficient of electrical conductivity of water when its temperature changes within the range of 20–55 °C. The temperature coefficient of electrical conductivity of water in sealed conductometric cells was measured at different degrees of filling the cells with distilled water and the rate of heating and cooling of water. The degree of filling of the cells varied within the range of 10–100 %, the rate of change in water temperature varied within the range of 0.04–2.00 °C/min. With a constant heating and cooling time of 15 minutes in all experiments, the change in speed was achieved by changing the temperature of the heating element. The integral temperature coefficient of electrical conductivity is calculated based on the initial and final values of electrical conductivity and water temperature in each measurement cycle. The dependences of the temperature coefficient of electrical conductivity on the rate of change in water temperature at several constant degrees of cell filling were obtained. It has been shown that with a constant ratio of the volumes of water and air in the cell and an increase in the rate of heating of water, the temperature coefficient of electrical conductivity of water decreases by 19–22 %. It has been established that at a constant rate of water heating, with a decrease in the volume of water in the cell, the temperature coefficient of electrical conductivity of water decreases by 40–42 %. The results obtained can be used to quantify the dissociation coefficient of carbonic acid, the mobility of hydrogen ions, as well as the intensity of the gas exchange process under various external influences on water. Refinement of data on the electrical conductive properties of water and processes at the water/air interface is necessary for the development of models of atmospheric phenomena and climate change, as well as for the creation of sensors for weak changes in environmental parameters for the purposes of both environmental monitoring and medical diagnostics.