Electrical Transport Research Articles

Beyond wages: The transformative role of strikes in accelerating transportation electrification

Transportation electrification is a critical step towards energy transition and low-carbon society, with wide-ranging social and economic impacts. This study examines the significant role of the 2023 United Auto Workers strike in the context of transportation electrification, with a focus on its implications for the automotive industry and labor market dynamics. Through an analysis of the strike’s immediate effects on production and long-term implications for labor practices and competitive strategies, this study explores how labor actions can influence the pace and direction of the transportation decarbonization efforts. We argue that the strike may accelerate automation and the adoption of non-unionized labor, potentially reshaping the future labor market and manufacturing landscape. To support a just and equitable transition, we call for incorporating the safeguarding of labor social benefits into the innovation of public policies and investment portfolios that incentivize the electric vehicle markets.

Electric transport as one of the ways to achieve climate neutrality in Europe: Problems of development and legal regulation in Ukraine

The study of ways to improve the regulatory framework for the use of green technologies is becoming increasingly important due to the exacerbating climate crisis, which is prompting a reduction in greenhouse gas emissions. The purpose of this study was to identify and describe the gaps in the current legislation on the development of electric transport, as well as to investigate the feasibility and effectiveness of the proposed changes in this area, which are intended to reduce the adverse impact of transport on the environment. The methodology of the study included formal logical, formal legal, comparative legal, as well as other general scientific and special scientific methods of cognition, a review of the current laws of Ukraine and draft laws submitted to the Verkhovna Rada of Ukraine aimed at improving the current legislation on electric transport, including the regulation of the use of personal light electric transport. An analysis of current legislation and draft laws submitted for consideration revealed that some laws contain provisions that hinder the development of electric transport, and the adoption of a series of draft laws could negatively affect the economic viability and ease of use of such transport. The study provided recommendations, based on the approaches of EU countries, to promote and motivate drivers to change their internal combustion engine vehicles to electric ones. The study resulted in a series of proposals to address the identified problems and shortcomings of the current legislation. Specifically, the study suggested ways to encourage drivers to change their internal combustion engine vehicle to an electric one, analysed the ways of developing and popularising personal electric vehicles, examined the current state of development of green infrastructure and availability of electric vehicle charging points, and proposed approaches to solving the issue of recycling electric vehicle batteries. The practical value of this study lies in the possibility of further use of the research findings and conclusions drawn therein to address the gaps in current legislation by submitting a draft law with the proposed relevant amendments

Strong correlation of electrical transport and magnetic properties to ionic states, structure, and morphology of Al-substituted Ni–Co ferrite systems: A comprehensive study

This paper presents the structure, morphology, magnetic, ionic states, and electrical transport characteristics of spinel Ni0.5Co0.5AlxFe2-xO4 (x = 0.0, 0.5, and 1.0) nanocrystalline ferrites, synthesized by using the sol-gel auto-combustion method. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to analyze the structural characteristics. The synthesized ferrites were found to have a crystallite size of less than 40 nm when the Rietveld method was applied to refine XRD patterns in single-phase cubic spinel-related structures that belong to the Fd-3m space group. Furthermore, since the ionic states are visible in X-ray photoelectron spectroscopy (XPS), variations in Al3+ ion concentration have been found to affect the locations, occupancy, and Wyckoff's cationic position of the ions as well as the lattice constant (a), the crystallite size (D), and the micro-strain of the composites. Thermogravimetric analysis was used to examine the temperature-dependent spinel phase formation and % weight loss of the sample. The x = 1.0 composition is said to be the best dielectric material out of the three samples since it has the highest polarization permittivity, the lowest dissipation factors, and exceptional temperature stability. These nanoparticles have relatively high impermanent magnetization values and are ferrimagnetic, according to the vibrating sample magnetometer (VSM) investigation. Additionally, it was found that the presence of Al3+ decreases the magnetization values of the spinel Ni0.5Co0.5AlxFe2-xO4 (x = 0.0, 0.5, and 1.0) system because the Al3+ exclusively occupies the Fe-sites, which reduces the super-exchange interaction between the Fe2+/Fe3+, Co2+/Co3+, and the Ni2+/Ni3+ ions. The unique magnetic characteristic of these compositions below 40 nm is predicted to make them appealing for storage applications.

Comparative studies of role of different structure factors in various physical properties of some simple liquid metals

In the current work, the comparison of the structure factors and pair correlation functions produced by using eight different theoretical models based on the Perckus-Yevick Hard Sphere (PYHS), Hard Sphere Yukawa (HSY), Mean Spherical Approximation (MSA), Generalized Mean Spherical Approximation (GMSA), Soft Sphere (SS), One-Component Plasma (OCP), Optimized Random Phase Approximation (ORPA) and Charged Hard Sphere (CHS) models for liquid metals viz. Li, Na, K, Rb, Cs, Mg, Zn, Ca, Al, Ga, In, Pb, Sn, Bi and Sb are carried out. Our own model potential is used with the Taylor (TY) screening function in the present computation. With this, certain physical properties such as electrical transport (electrical resistivity), vibrational property (phonon dispersion), dynamical property (velocity autocorrelation function (VACF)) and static (long wavelength of structure factor) properties has also been calculated. When the several theoretical models of the structure factors of the researched simple liquid metals are compared, it is discovered that the experimental data is consistent and in good agreement with the theoretical models.

Socio-economic development impacts, attendant challenges and mitigation measures of infrastructure vandalism in Southern Africa

ABSTRACT This paper explores the scourge of infrastructure vandalism in South Africa and Zimbabwe, with a particular focus on electricity and rail transport companies within the two countries. The paper sought to document the manifestation of infrastructure vandalism; identify the socio-economic impacts of infrastructure vandalism; and explore the challenges of curbing vandalism. The paper reveals that vandalism mainly manifests through copper cable theft; vandalism of transformers, pylons and rail infrastructure; theft of transformers; and tampering with railway points machines. Vandalism of infrastructure comes with direct and costs to the utility companies, as well as negatively impacting the economy, essential services, and the overall community safety. Involvement of employees in the criminal activities, corruption, incessant power cuts, well organised crime syndicates and a weak legal framework were identified as the current challenges to anti-vandalism efforts. The paper also proffers mitigatory measures to deal with the scourge.

Anomalous Hall effects in chiral superconductors

We report theoretical results for the electronic contribution to thermal and electrical transport for chiral superconductors belonging to even or odd-parity E1 and E2 representations of the tetragonal and hexagonal point groups. Chiral superconductors exhibit novel properties that depend on the topology of the order parameter and Fermi surface, and—as we highlight—the structure of the impurity potential. An anomalous thermal Hall effect is predicted and shown to be sensitive to the winding number, ν, of the chiral order parameter via Andreev scattering that transfers angular momentum from the chiral condensate to excitations that scatter off the random potential. For heat transport in a chiral superconductor with isotropic impurity scattering, i.e., point-like impurities, a transverse heat current is obtained for ν = ±1, but vanishes for |ν| > 1. This is not a universal result. For finite-size impurities with radii of order or greater than the Fermi wavelength, R ≥ ℏ/pf, the thermal Hall conductivity is finite for chiral order with |ν|≥ 2, and determined by a specific Fermi-surface average of the differential cross-section for electron-impurity scattering. Our results also provide quantitative formulae for analyzing and interpreting thermal transport measurements for superconductors predicted to exhibit broken time-reversal and mirror symmetries.

Enhancing thermoelectric performance of AB2Sb2-type Zintl phase through band shaping and lattice distortion

AB2Sb2-type Zintl phases, especially Mg3Sb2, have garnered widespread attention in virtue of their nontoxic constituent elements and outstanding thermoelectric performance in n-type materials. However, the p-type counterpart of AB2Sb2 still struggles with a low figure of merit zT, primarily because of the limited valence band degeneracy, large band effective mass, and relatively high thermal conductivity. Here we simultaneously optimize the electrical and thermal transports of p-type AB2Sb2-based materials through shaping the band edge and distorting the crystal lattice. By alloying Zn at Mg2 site and Ca at Mg1 site, we successfully decorate the crystal lattice of Mg3Sb2 in real space and thereby modify the band structure in reciprocal space. Zn alloying promotes the band degeneracy while Ca alloying reduce the single band effective mass, which largely promotes the transport of charge carriers. Moreover, the distorted crystal lattice effectively blocks the heat-carry phonons to reduce the lattice thermal conductivity κL. A high zT of 0.81 is finally realized at 750 K in our Zn/Ca co-alloyed samples, which is three times larger than that of Mg3Sb2 matrix. Our work opens new possibilities for the synthetic optimization of both electrical and thermal transports in Zintl phase and other thermoelectric systems.

Isolating electrical and cryogen flow for safe operation and design validation experimentation of HTS power cables for electric transportation

The need for protecting the cryogenic infrastructure during a fault in high-temperature superconducting (HTS) power distribution systems of electric transport platforms is highlighted. A dual grounding scheme with an isolator between the electrical and cryogen flow paths of HTS power cables is needed. Finite element analysis of the electric field distribution of the vacuum jacketed isolator showed electric field intensity at the triple points. The electric field intensity at the triple points is reasonable if high vacuum quality is maintained. There is a need for further investigations for design validation with experimentation of practical designs for effective isolation and protection of cryogenic infrastructure from damage during an electrical fault in a section of the power distribution network of electrical transport platforms, such as an electric aircraft or ship.

Entangling imidazolium-based ionic liquids and melanins: A crossover study on chemical vs electronic properties and carrier transport mechanisms

Melanins (mel) are a class of pigments that are nearly ubiquitous and among the oldest compounds found in nature. However, their practical application has been limited due to their low solubility in water and in most organic solvents. Recent research on polydopamine has revealed that ionic liquids (ILs) not only enhance melanin’s dissolution but also fine-tune its redox properties through specific dipolar interactions. In this study, we expand upon previous investigations by customizing new suspensions on a broader range of melanins. Concerning ILs, we focus on imidazolium based ILs, tailoring their chemical properties (pKa) and structural characteristics (cation radius, anion radius).The melanins under consideration include synthetic polymers derived from the oxidative polymerization of 5,6-dihydroxyindole (DHI) and its 2-carboxylic acid counterpart (DHICA), as well as the natural pigment Sepiomelanin (Sepiomel), which is isolated from the ink sack of cuttlefish. Our comparative analysis between neat ILs and ILs-mel responses reveals several key findings: the increase in solubility, the tuning of the redox ability, the decrease of the ionic charge resistance (from MΩ τo kΩ); the partial removal of the electrical polarization effects and the delocalized ionic charge hopping mechanisms in conductivity; the increase of the free ionic diffusion mobility and Debye lengths. Notably, electrical transport is influenced by both the chemical features and the steric hindrance in the ILs as well as the specific type of melanin employed. These factors contribute to the high order correlation between free ionic charge densities and their corresponding Debye lengths. Consequently, our findings suggest that for these complex systems, an improved model extending beyond a simplified electrostatic interaction mechanism is required.

A green laboratory approach to medical sample transportation between two medical laboratories: Assessing the environmental impact of drone, combustion car, and electric car transportation of medical samples

A green laboratory approach to medical sample transportation between two medical laboratories: Assessing the environmental impact of drone, combustion car, and electric car transportation of medical samples

Thermoelectric properties and thermal transport in two-dimensional GaInSe3 and GaInTe3 monolayers: A first-principles study

We here report the electronic structure calculation of GaInSe3 and GaInTe3 monolayers with the P3m1 (no. 156) space group. The electronic structure and thermoelectric properties of the monolayers are calculated through the Vienna Ab initio Simulation Package and BoltzTraP2 codes. The dynamic and thermodynamic stabilities were verified by calculating their phonon spectra and simulating ab initio molecular dynamics. The monolayers were found to have a direct bandgap, with both PBE + SOC and HSE06 + SOC potentials. The lattice thermal conductivity of GaInTe3 monolayer calculated using Phono3py code shows ultra-low values due to enhanced phonon–phonon scattering. Combining electrical and thermal transport, the values have been evaluated. Importantly, the p-type GaInTe3 has excellent thermoelectric properties at 700 K, with a zT value of 2, indicating that the p-type GaInTe3 has potential application in the field of thermoelectricity.

Effects of Ni2+ modified La0.67Ca0.33MnO3 ceramics on their temperature coefficient of resistivity and magnetoresistance properties

Element-modified La0.67Ca0.33MnO3 (LCMO) ceramics have been a major research subject in the past decades due to their various electromagnetic properties and potential applications in infrared detection and magnetic storage devices. However, its electromagnetic transport mechanism has not been fully elucidated and its properties need to be further optimized for practical applications. Here, we report the effect of Ni2+ doping on the structural, magnetic, the temperature coefficient of resistivity (TCR) and magnetoresistance (MR) properties of La0.67Ca0.33Mn1-xNixO3 (LCMNO) ceramics. All samples were synthesized by the sol-gel method and were in pure phase. XRD refinement results show a decrease in lattice constants and cell volume of LCMNO ceramics with increasing Ni2+ content. The XPS study confirms the reduction of the Mn3+/Mn4+ ratio and indicates that oxygen vacancies occur in LCMNO ceramics due to the Ni2+ doping. Curie-Weiss fitting results suggest ferromagnetic superexchange coupling between Ni2+ and Mn3+(4+) ions. The electrical transport properties of LCMNO ceramics were further investigated using the spin polaron hopping model in the high temperature range and the various competing scattering mechanisms in the low temperature range. In addition, double resistivity peak behavior is observed at x = 0.04 and 0.05. Furthermore, the TCR of the LCMNO ceramics increased to 45.4 %·K−1 (x = 0.01), while the MR increased to 67.9 % (x = 0.03), respectively. Our studies contribute to a better understanding of the electromagnetic properties of LCMNO ceramics.

Review of cryogenic power conversion and its potential in future all electric transportation systems: from silicon age to WBG era

Cryogenic power electronic conversion (< 123 K) is expected to offer higher efficiencies for future all-electric transportation platforms. Low temperature operation of converters together with integration of wide bandgap devices (WBG) can enable higher switching frequencies with reduced filtering components. This paper briefly reviews the passive components involved in the development of a cryogenic converter. The paper also reviews in detail the converter development with WBG devices by far, and provides a discussion on benefits achieved, and challenges in terms of auxiliary components and measurements. The last part of the paper gives a discussion on envisioned challenges, and different research directions for future superconducting power conversion systems.

Correlation between structural, morphological, and electrical transport properties of nano-dimensional Tellurium thin film by low energy ion beam irradiation

Tellurium (Te), an emerging semiconductor material, exhibits intriguing physical properties in low-dimensional forms. This study investigates the structural, morphological, and transport properties of low-dimensional Te thin film deposited by physical vapor deposition after 400 keV Kr2+ ion irradiation with varying fluences of 1 × 1013, 5 × 1013, and1 × 1014 ions-cm−2. The X-ray diffraction (XRD) pattern reveals the hexagonal phase of pristine Te. As ion fluence increases, intensity of the XRD peaks decreases and the full-width half maxima (FWHM) increases, indicating a reduction in crystallinity. The intensity of the Raman peak decreases upon irradiation, resulting in a red shift in the spectra of the irradiated sample. The evolution of morphology at different fluences has been examined with atomic force microscopy (AFM) measurements. The results indicate the segregation of grains and an increase in root mean square (RMS) roughness from 2.59 pm to 5.11 pm with ion fluence up to 5 × 1013 ions-cm−2. At the highest fluence, i.e., 1 × 1014 ions-cm−2, there is an agglomeration of grains, and hence a decrease in RMS roughness to 3.92 pm is observed. The DC resistivity measurement indicates the semiconducting nature of all films. Additionally, this measurement signifies the rapid decrease in activation energy at both band-to-band conduction and nearest neighbour hopping (NNH) conduction. Following irradiation, Hall measurement demonstrates a decrease in the concentration of charge carriers and an increase in resistivity due to scattering originating from grain boundaries. However, when the fluence is increased to 1 × 1014 ions-cm−2, there is a reduction in resistivity and an increase in carrier concentration with enhanced Hall mobility in comparison to pristine Te. Therefore, this study showcases that low-energy ion irradiation has a significant impact on the modification of the structure, morphology, and electrical transport properties of semiconducting Te thin film.

Improved electrical transport properties of La0.7Ca0.3−xKxMnO3 (0.0 ≤ x ≤ 0.3) films grown on La0.3Sr0.7Al0.65Ta0.35O3 (00l) substrates by sol–gel spin coating method

Herein, La0.7Ca0.3−xKxMnO3 (LCKMO) films with highly oriented growth were prepared on La0.3Sr0.7Al0.65Ta0.35O3 (00l) substrates by sol–gel spin coating method. Comprehensive analysis of microstructure, surface morphology, ion valence, and electrical transport properties of LCKMO films indicates that the substitution of K+ ions for Ca2+ ions increased the ratio of Mn4+/(Mn3+ + Mn4+), narrowed the one electron bandwidth, and enhanced double exchange mechanism and electron–lattice coupling. Moreover, the doping of K+ ions induced the dense and uniform conical-structured growth of grains on the surface of the films. Results demonstrated that at x = 0.1, LCKMO film exhibited the maximum TCR of 17.84% K−1 at 253.07 K, which was 31.76% higher than that of previously reported La1−x−yCaxKyMnO3 ceramic with the highest TCR. Further theoretical insights into the effects of Ca/K co-doping on electrical transport properties were supplemented.

Investigation of the carbon monoxide resistance of platinum catalysts prepared via pulse alternating current technique

The platinum catalysts based on carbon black and carbon nanotubes supports have been obtained via pulse alternating current technique. The synthesized Pt/C catalysts showed better electric transport characteristics and the carbon monoxide poisoning resistance in comparison with the commercial Pt/C owing to both the size of the platinum nanoparticles and their agglomeration on the support surface, and the morphology of the carbon support.

Calculating the Density Energy of Se100-XGeX and Se62Ge35X3 Semiconductor Materials

In this paper, chalcogenide glasses are studied using a range of experimental techniques for the purpose of understanding their electrical properties with the aim of providing new strategies for producing a new class of electronic devices made of advanced amorphous materials. The electrical properties of chalcogenide glass are very low cost to produce competitive devices; hence, a deeper understanding of their electrical transport properties may provide the necessary insight to enhance merit. For this purpose, the electrical properties studied by some researchers were relied upon, mathematical equations were performed and the program is designed to compute the energy state density in both extended and localized systems region of Se100-xGex with (x = 5, 25, 28, 30 and 38) and Se62Ge35X3 glasses (where X is Sb, Sn, or Bi) in different concentrations. Characterizing the electrical properties of Se100-xGex and Se62Ge35X3 glasses use to determine the density of energy states. The results of electrical measurements confirmed the presence of two mechanisms of electrical conduction: conduction in extended states at high temperatures and conduction in localized states at medium temperatures. Effective substitution results in a change in the local and extended state coefficients. This effect was measured as a function of concentration.

Structural, Microstructural, and Electrical Properties Study of Pb(Sn0.45Ti0.55)O3 Ceramics

We undertook a comprehensive investigation of the the structural, dielectric, and electrical characteristics of Pb(Sn0.45Ti0.55)O3 ceramics prepared using the conventional solid-state route. A meticulous preparation protocol, involving solvating various precursors, was followed by extensive characterization employing X-ray diffraction, scanning electron microscopy, and dielectric studies. The synthesized sample features a single-phase tetragonal structure with P4mm symmetry. Using impedance spectroscopy, electrical transport properties of the polycrystalline Pb(Sn0.45Ti0.55)O3(PST) ceramic were studied in detail. Relaxation and conduction mechanisms of the material were inferred using complex impedance, complex electric modulus, and frequency dependent ac conductivity analysis. Impedance spectroscopy results reveal the range of frequencies in which the grain, grain boundary, and electrode effects are dominant. Above certain temperatures, the imaginary component of impedance (Z//) exhibits some resonant type peaks at different frequencies indicating relaxor nature of the sample. The activation energy obtained for both the relaxation and conduction process indicates the role of doubly-ionized oxygen vacancy in the conduction mechanism of the sample. The dielectric relaxation occurring at low frequency and high temperatures is related to the space charges associated with the ionized oxygen vacancies being trapped at the grain boundaries. The Cole-Cole plots confirm the poly-dispersive nature of dielectric relaxation in the sample.

Effects of working pressure during magnetron sputtering on thermoelectric performance of flexible p-type Bi0.5Sb1.5Te3 thin films

The influence of argon working pressure during magnetron sputtering on thermoelectric properties has been investigated on p-type Bi0.5Sb1.5Te3 flexible films deposited at various working pressures in the range from 2 to 5 Pa. The microstructure and orientations, atomic compositions, and carrier concentration could be regulated by adjusting the working pressure, due to the size-dependent inhibition of the deposition of the sputtered Bi, Sb, and Te atoms from argon ions. Profiting from the occurrence of the (006) orientation, the nearest stoichiometric ratio, the highest carrier concentration and mobility, and the quantum confinement effect, the film deposited at 4 Pa displays the maximum power factor of 1095 μW m−1 K−2 at 360 K. These results suggest that the electrical transport properties of the sputtered flexible thermoelectric thin films can be synergistically optimized by selecting an appropriate working pressure.

Electric field influence on the non-zero temperature resistance of carbon nanotube polymer nanocomposites with subbands effect

The effective electrical resistivity of carbon nanotubes (CNT)-based polymer nanocomposites is studied using an analytical model based on the percolation theory. The CNTs are considered as rod-like conductors that are aligned or randomly dispersed in the polymer to transport electrons by tunneling. When assessing non-zero temperature electrical resistivity, the tunneling effect considers the thermally energized electron transmission that occurs between each coupled pair of CNTs by the electrical transport model. The modeling technique consists of three steps: identifying the percolating network from the primary formation of CNTs, initial prediction of resistivity by equivalent resistor network, computation of the displacements of CNTs for the resistance change. Taking into consideration the behavior of tunneling in the percolation transition zone, a good agreement is obtained between the model results and experimental data. The verified code is used to investigate the sensitivity for different orientation states, aspect ratios and mode numbers. The results reveal lower sensitivity for higher mode numbers as collateral with the influence of increasing randomness.