Electrical Transport Research Articles

The anomalous Hall effect in the epitaxial-grown semiconducting CuCo2O4 thin film

The high-quality inverse spinel CuCo2O4 thin films are epitaxially grown on (001) MgAl2O4 substrates by radio frequency magnetron sputtering. The electrical transport properties exhibit typical semiconducting characteristics, accompanying the enhancement of resistivity with the thinning of CuCo2O4 thickness. The transport properties could be well understood by the Mott variable range hopping model. The anomalous Hall effect with a clear hysteresis loop is observed below 100 K, indicating the existence of out-of-plane magnetization in the epitaxial-grown CuCo2O4 films. In addition, the negative magnetoresistance at low temperature reverses to the positive magnetoresistance (≥100 K), which is related to the changes from the decrease in spin/carrier scattering under the magnetic field at low temperature to the enhancement of carrier deflection due to the conventional Lorenz force (≥100 K). The observed physical properties are closely related to the orbital occupation of Cu ion in CuCo2O4 films, which is a significant difference compared to that of documented metallic NiCo2O4. This work is a good comprehensive study of inverse spinel oxide thin films.

Synthetic nanoarchitectonics with ultrafast Joule heating of graphene-based electrodes for high energy density supercapacitor application

This study presents a novel approach for the development of high-performance supercapacitor (SC) electrodes using the Flash Joule Heating (FJH) method. Here, we report a direct and rapid synthesis of graphene-based electrodes via FJH. The technique involves microwave-assisted decomposition of citric acid and urea to form CNDs as precursors, followed by Flash Joule Heating (FJH) leading to the formation of graphene in seconds. The scalability of this method paves the way for the rapid production of graphene-based SC electrodes. Based on the characterisation using XRD, Raman, SEM and TEM, the FJH-treated CNDs yielded graphene on carbon fibre cloth with well-defined morphologies leading to superior electrochemical performance in supercapacitors. The FJH processed electrodes exhibited exceptional electrochemical performance with a specific capacitance of 279 F g⁻¹ at 1 A g⁻¹, significantly outperforming unflashed and low current flash processed electrodes. This exceptional performance can be attributed to the formation of high-quality, few-layered graphene with enhanced electrical conductivity and efficient ion transport properties. Moreover, a Symmetric supercapacitor is also assembled which demonstrated a specific capacitance of 106.5 F g⁻¹ at 1 A g⁻¹. It also exhibited an impressive energy density of 44.4 W h kg−1 at a power density of 1000 W kg⁻¹. This work demonstrates the feasibility of FJH as a rapid, scalable and cost-effective technique for the production of high-performance graphene-based electrodes for supercapacitor applications.

Analisis Jejak Karbon Dalam Proses Pembelajaran Kelas

The environmental issue should have already become a primary concern and a crucial focal point for sustainability. One of the influencing factors is carbon dioxide (CO2) emissions, which have a significant impact on climate change. Electricity consumption contributes the largest share of carbon emissions in the energy sector, followed by transportation activities. This study aims to compare the levels of carbon emissions generated and the costs incurred in the face-to-face and online learning processes involving electricity consumption and transportation activities. The research employs a qualitative approach with a case study method. The population in this study consists of active accounting students at Bunda Mulia University, Serpong Campus, and no sampling is conducted to obtain the entire data, which includes primary data from observation and questionnaire. The tools used in this study are Microsoft Excel and jejakkarbonku.id for processing research samples. The results of the study indicate that electricity consumption is higher in face-to-face learning compared to online learning. Additionally, a greater level of carbon emissions is produced from face-to-face learning than online learning, with building electricity consumption surpassing transportation activities. The costs incurred for face-to-face learning are also higher than those for online learning. Despite face-to-face learning being the largest contributor to consumption, carbon emissions, and costs, it is perceived as more effective than online learning. Therefore, there is a need for solutions to address environmental issues while maintaining the effectiveness of education.

Online optimal scheduling for battery swapping charging systems with partial delivery

Battery swapping–charging system (BSCS) is a promising operating paradigm to provide centering charging and battery swapping service for electric vehicles in transportation electrification. Facing real-time information on battery demand under the limited transporting trucks, flexible online optimization of battery delivery and transportation routing is essential for meeting practical requirements. This paper investigates the real-time scheduling problem in BSCS, considering the battery partial delivery, energy demand, delivery deadline, and vehicle routing. Considering the non-deterministic polynomia hardness of battery transportation, the offline BSCS is a time-consuming task and is unsuitable for the online setting. A Lagrangian relaxation-based Benders decomposition is proposed for parallel and real-time implementation, improving the scheduling efficiency. To tackle future information such as battery demands and delivery deadlines, by introducing the dummy copy, the offline algorithm is embedded within a rolling horizon framework to solve in real-time repeatedly. Finally, case studies using real road maps in Shanghai and Belgium have verified the validity of the proposed online framework and confirmed the necessity of considering partial delivery in enhancing the operation flexibility of BSCS. The computational efficiency of the proposed algorithm is studied under different scales of the road network, and the profit from partial delivery and online implementation are highlighted.

Computational modeling of CH4 and CO2 adsorption on monolayer graphenylene: Implications for optoelectronic properties and hydrogen production

Graphenylene (GP) is a two–dimensional carbon allotrope with a hexagonal lattice structure containing periodic pores. The unique arrangement of GP offers potential applications in electronics, optoelectronics, energy storage, and gas separation. Specifically, its advantageous electronic and optical properties, make it a promising candidate for hydrogen production and advanced electronic devices. In this study, we employ a computational chemistry–based modeling approach to investigate the adsorption mechanisms of CH4 and CO2 on monolayer GP, with a specific focus on their effects on optical adsorption and electrical transport properties at room temperature. To simulate the adsorption dynamics as closely as possible to experimental conditions, we utilize the self–consistent charge tight–binding density functional theory (SCC–DFTB). Through semi–classical molecular dynamics (MD) simulations, we observe the formation of H2 molecules from the dissociation of CH4 and the formation of CO + O species from carbon dioxide molecules. This provides insights into the adsorption and dispersion mechanisms of CH4 and CO2 on GP. Furthermore, we explore the impact of molecular adsorption on optical absorption properties. Our results demonstrate that CH4 and CH2 affects drastically the optical adsorption of GP, while CO2 does not significantly affect the optical properties of the two–dimensional material. To analyze electron transport, we employ the open–boundary non–equilibrium Green's function method. By studying the conductivity of GP and graphene under voltage bias up to 300 mV, we gain valuable insights into the electrical transport properties of GP under optical absorption conditions. The findings from our computational modeling approach might contribute to a deeper understanding of the potential applications of GP in hydrogen production and advanced electronic devices.

FORMATION OF TRANSPORT AND LOGISTICS CLUSTERS AS AN EFFECTIVE TOOL FOR ENSURING SUSTAINABLE DEVELOPMENT OF TRANSPORT

The formation of transport and logistics clusters is an effective tool for ensuring sustainable transport development. They help to increase efficiency, reduce costs, introduce innovations and reduce environmental impact. For the successful development of transport and logistics clusters, it is necessary to take into account modern challenges and actively use the latest technologies and innovative approaches. The article is devoted to the study of the role of transport and logistics clusters in ensuring sustainable development of transport. To achieve this goal, an analytical review of data from various sources was conducted to identify the relationship between the formation of transport and logistics clusters and sustainable development. It was found that today the most serious challenge facing the transport sector is to significantly reduceemissions and increase sustainability. The European Green Deal, an EU action program centered on an ambitious plan to transition to a climate-neutral Europe by 2050, is studied. Nine areas of the European Green Deal are identified. The main areas of innovation in transport are identified (electric transport, autonomous vehicles, hydrogen fuel cells, intelligent transport systems, hyperloop). The proposals set out in three White Papers of the European Union are highlighted. It is confirmed that the formation of transport and logistics clusters can be an effective tool for ensuring sustainable development of transport through the development and application of innovative technologies. It has been determined that the formation and functioning of clusters on the principles of social responsibility is an objective necessity for the development of the economy and society.In this regard, the main goal of organizing and operating a clusteron the principles of social responsibility shoud simunltaneously include requirements to ensure economic and social development, and to achieve the welfare of partnerts and society as a whole. The results of the study can be used to substantiate the feasibility of forming transport and logistics clusters as a tool for ensuring sustainable development.

MBE growth of Ge1−x Sn x devices with intrinsic disorder

We discuss the electrical properties of molecular beam epitaxy (MBE) grown, modulation doped, Ge1−x Sn x quantum well devices. A consequence of the epitaxial growth process is that electronic disorder is introduced even in modulation doped quantum well structures and electrical transport properties that are characteristic of a high level of disorder are apparent. MBE growth of this material also results in the surface segregation of elemental β-Sn in the way that has been observed utilizing other epitaxial growth methods. A thermally activated, p-type mobility is a clear feature of the electrical properties with generally temperature independent hole densities ∼1012 cm−2 from the measured Hall effect and coming from the modulation doping. We present a discussion of Hall effect measurements in this disordered regime. The percolation carrier density in MBE modulation doped GeSn is in the region of ∼1 × 1012 cm−2 although Hall measurements in this regime are difficult to quantify when the resistivity >(h/e 2). In this notation h is Planck’s constant and e is the unit of charge. Conductivities (σ) as low as ∼0.028 × (e 2/h) × square can be measured in the four-contact ac configuration and the temperature dependence indicates a mobility edge in these p-type devices below ∼2 × 1012 cm−2. At lower temperatures (<∼1 K) the presence of a Coulomb gap can be determined using dc transport, constant voltage measurements where small ac current excitation is not available experimentally. This two-contact configuration can determine σ down to ∼10−6 × (e 2/h), deep into the localization regime, revealing a hopping conductivity dominated system. We discuss the relevance of these electrical properties for MBE grown GeSn devices.

Improving the Efficiency of Electric Vehicles: Advancements in Hybrid Energy Storage Systems

Electric vehicles (EVs) encounter substantial obstacles in effectively managing energy, particularly when faced with varied driving circumstances and surrounding factors. This study aims to evaluate the performance of three different control systems in a fully operational hybrid energy storage system (HESS) installed in the Nissan Leaf. The objective is to improve the performance of EVs by focusing on optimising energy management in response to different global environmental and driving circumstances. This study utilises an analytical strategy by developing a distinct energy management system model using MATLAB/Simulink. This model is specifically designed for optimising the integration and control of batteries and supercapacitors (SCs) in a fully active HESS. This model mimics the performance of the controllers under three different driving cycles—Artemis rural, Artemis motorway, and US06. The findings demonstrate notable progress in managing the battery state of charge (SOC) and the system’s responsiveness, especially when employing the radial basis function (RBF) controller. This study emphasises the capacity of HESSs to enhance the effectiveness and durability of EVs, therefore promoting wider acceptance and progress in electric transportation technology.

Integrating system dynamics and agent-based modeling: A data-driven framework for predicting electric vehicle market penetration and GHG emissions reduction under various incentives scenarios

As the growing deployment towards transportation electrification, a critical focus has emerged on quantifying the reduction contribution of greenhouse gas emissions from electric vehicles towards achieving carbon neutrality under diverse policy scenarios in the future. This necessitates a dynamic model that captures the evolving composition of the vehicle fleet and accurately forecasts the penetration and developmental trajectory of the electric vehicles in the car market. However, previous studies have largely overlooked the heterogeneity in user usage attributes, rendering them less effective in evaluating the impact of usage-based incentives on electric vehicle market penetration. To bridge this research gap, this study introduces an innovative, data-driven framework that integrates system dynamics and agent-based model. The proposed model can predict levels of electric vehicle penetration and corresponding greenhouse gas emission reductions within the private passenger vehicle sector, under a variety of policy scenarios. Our findings indicate that usage-based incentives, when implemented with optimal intensity, yield more significant emission reduction impacts and long-term economic benefits compared to conventional purchase-based subsidy. These insights not only furnish actionable policy suggestions to expedite the electric vehicle industry's growth in China but also offer valuable implications for other countries seeking to implement effective strategies for combating climate change and fostering sustainable transportation initiatives.

Justification of key factors regarding the application of prospective ecological transport in the urban passenger transportation system

Research objective. Justification of the key factors that have an impact on the introduction of promising ecological transport in the system of urban passenger transport in order to improve the quality of transport services for passengers and improve ecology in densely populated cities. Materials and methods. To achieve the goal, the fuzzy Dematel method is used, which is based on graph theory and allows to classify all available factors that influence decision-making based on cause-and-effect relationships. Results. The eight key factors that form the transport project and the factors that have a significant impact on them are substantiated for the implementation of the transport project of the implementation of promising ecological passenger transport on urban routes into the transport system of urban passenger transportation. These include the level of development of modern transport technologies when transporting passengers on city routes and the availability of their support centers; the availability of financial programs for updating/restructuring the rolling stock fleet of the motor vehicle enterprise and the availability of the appropriate legal framework for preferential operation of electric passenger transport; rapid adaptation of the transport infrastructure of a modern city for the operation of ecological transport; compliance of ecological transport with the transport characteristics of the passenger transportation route; operational properties of a modern electric bus; the effect of relevant legislative initiatives regarding benefits for the purchase and costs of operating electric vehicles. Scientific novelty consists in identifying the interrelationships between the factors that form the transport project and the factors that have a significant influence on them, on the implementation of the transport project of the implementation of promising ecological passenger transport on urban routes into the transport system of urban passenger transport, which allows to estimate the possible economic costs of road transport enterprises carrying out passenger transportation. Practical significance lies in the determination of key factors that can be used for the implementation of a transport project for the use of promising ecological passenger transport in the system of urban passenger road transport

Unveiling interface engineering dynamics between Ti and Ga2O3 nanowire

In this study, we investigate the interfacial reactions between Ga2O3 nanowires (NWs) and Ti contacts during annealing processes through in-situ transmission electron microscopy (TEM) observations. A thin Ga3Ti2 intermetallic compound was observed to form at the Ti/Ga2O3 interface, coinciding with a transition in the NW device’s contact behavior from Schottky to ohmic upon annealing at 470 °C. Utilizing in-situ TEM, we monitored the evolution of the Ga3Ti2 layer, revealing Ga atoms as the primary diffusing species within the Ga2O3 NW, evidenced by asymmetric diffusion at the interface. Ga3Ti2 intermetallic compound effectively reducing the energy barrier between Ga2O3 NW and Ti electrode, contributing to linear electrical transport characteristics. This investigation underscores the significance of interface engineering and offers valuable insights for future electronic applications utilizing Ga2O3 NWs.

A hybrid electric power supply system for a livestock farm using battery electric transport.

A hybrid electric power supply system for a livestock farm using battery electric transport.

High wide-temperature-range thermoelectric performance in GeTe through hetero-nanostructuring

GeTe is emerging as promising medium-temperature thermoelectric material due to its highly competitive performance and good mechanical properties. Strong Rashba spin splitting was harnessed to markedly improve the Seebeck coefficient and power factor of Bi and Sn codoped GeTe at low-medium temperature. Moreover, it is found that Bi-Sn-Cu doping reduces the phase-transition temperature to extend better electrical transport behavior of cubic phase to low temperature. As a result, the electrical transport properties in low-medium temperature were overall enhanced. In the meanwhile, endotaxial hetero-nanostructures efficiently scatter phonons and play a dominant role on affecting phonon propagation. The lattice thermal conductivity was reduced to 0.2 W m−1K−1 at 673 K. Drive by strengthening Rashba effect and endotaxial hetero-nanostructures, a record-high average ZT (300–823 K) of 1.6 and a high ZT of 2.1 were obtained in lead-free GeTe-based compounds. The vast increase of ZT promotes GeTe as a promising candidate for a wide range of applications in waste heat recovery and power generation.

Synthesis of epitaxial LuN films

Epitaxy of rare-earth nitride films are crucial for studying their physical properties and offer significant potential for applications in spintronics and optoelectronics. However, synthesizing single-crystalline LuN presents significant challenges, leading to a limited understanding of its properties. In this study, we successfully achieved the epitaxial growth of (001)-oriented LuN films on YAlO3 (110) substrates by reactive magnetron sputtering epitaxy. Electrical transport measurement at low temperatures reveals that the LuN film exhibits semiconducting behavior between 300 K and 2 K, with an activation energy of approximately 0.01 eV. Notably, negative magnetoresistance was observed below 12 K, which can result from the defects and magnetic impurities in LuN films. Our results uncover the electronic and magnetic properties of epitaxial LuN films.

Modeling the impact of end-user flexibility and bill structure on future transmission grid load

Demand-side flexibility is expected to play a key role during the transition towards renewable-dominated power systems and the electrification of transportation and heating sectors. Following this, massive investments in transmission capacities will be required, which may be reduced if end-users appropriately exploit their flexibility from the edge of the network. However, modeling the end-user flexible behavior and its impact on transmission grid load during the planning stage is not straightforward. The rationale behind this is that it results from the aggregation of atomistic loads and that it may be unlocked implicitly, i.e., via the structure of electricity bill. In this paper, assuming economically rational end-users, we develop an equilibrium model of end-users minimizing their electricity bill, while taking into account the elasticity of electricity prices. The proposed approach is used to derive updated transmission load projections, highlighting the benefits of considering end-user flexibility for transmission system planning.

Electron Heating in High Mach Number Collisionless Shocks.

The energy partition in high Mach number collisionless shock waves is central to a wide range of high-energy astrophysical environments. We present a new theoretical model for electron heating that accounts for the energy exchange between electrons and ions at the shock. The fundamental mechanism relies on the difference in inertia between electrons and ions, resulting in differential scattering of the particles off a decelerating magnetically dominated microturbulence across the shock transition. We show that the self-consistent interplay between the resulting ambipolar-type electric field and diffusive transport of electrons leads to efficient heating in the magnetic field produced by the Weibel instability in the high Mach number regime and is consistent with fully kinetic simulations.

Structural implications of ionic conduction in LaAlO3–Ce0.8Gd0.2O2-δ composite solid electrolyte

Investigations were done on the combinations of perovskites and fluorite structured composite electrolyte materials to check the possible enhancement of the ionic conductivity. For this purpose, the compounds, LaAlO3 (LAO) and Ce0.8Gd0.2O2-δ (CGO) were mixed in the weight ratios of 3:1, 2:2, and 1:3 to develop cost-effective composite electrolyte materials. Conductivity spectroscopy techniques were used to examine the dc electrical transport properties. Thermal properties were investigated using thermogravimetry analysis. Fourier transform spectroscopy was employed for bond structural study, while an X-ray diffractometer pattern analysis was employed to ensure the formation of composite structure. Scanning electron microscopy and energy dispersive X-ray spectroscopy studies confirm dense microstructure by a suitable weight proportion of component, homogeneous grain dispersion, and elemental confinement. The electrical behavior of composite electrolytes was demonstrated by electrochemical impedance spectroscopic analysis methods, which instigate the highest value of the conductivity of the order of 0.14x10−2 S cm−1 and lower activation energy value (0.72 eV) at temperature 700 °C for composite with LAO-CGO weight ratio of 1:3.

Tracking Cation Exchange in Individual Nanowires via Transistor Characterization.

Cation exchange is a versatile method for modifying the material composition and properties of nanostructures. However, control of the degree of exchange and material properties is difficult at the single-particle level. Successive cation exchange from CdSe to Ag2Se has been utilized here on the same individual nanowires to monitor the change of electronic properties in field-effect transistor devices. The transistors were fabricated by direct synthesis of CdSe nanowires on prepatterned substrates followed by optical lithography. The devices were then subjected to cation exchange by submerging them in an exchange solution containing silver nitrate. By removal of the devices from solution and probing the electrical transport properties at different times, the change in electronic properties of individual nanowires could be monitored throughout the entire exchange reaction from CdSe to Ag2Se. Transistor characterization revealed that the electrical conductivity can be tuned by up to 8 orders of magnitude and the charge-carrier mobility by 7 orders of magnitude. While analysis of the material composition by energy dispersive X-ray spectroscopy confirmed successful cation exchange from CdSe to Ag2Se, X-ray fluorescence spectroscopy proved that cation exchange also took place below the contacts. The method presented here demonstrates an efficient way to tune the material composition and access the resulting properties nondestructively at the single-particle level. This approach can be readily applied to many other material systems and can be used to study the electrical properties of nanostructures as a function of material composition or to optimize nanostructure-based devices after fabrication.

Confronting mobesity is vital for the global electrification of transport

Confronting mobesity is vital for the global electrification of transport

Sustainable transport in the face of the energy crisis related to the war in Ukraine

The energy crisis caused by Russia’s aggression in Ukraine has had a huge impact on the functioning of many countries in various spheres. The Russian Federation was the main supplier of many raw materials, which had to be abandoned as a result of the sanctions that were imposed. Consequently, the prices of various commodities – primarily natural gas, crude oil and coal – have risen. This posed a particular challenge for Poland, which is highly dependent on coal. At the same time, Poland, being a Member State of the European Union, has committed to achieving the goals of climate neutrality and the related concept of sustainable transport. In this light, the author analysed the issue of striving for climate neutrality and sustainable transport in the conditions of the crisis caused by the war in Ukraine. It seems appropriate, for instance, to determine whether the energy crisis has led to a collapse of the European Union’s climate policy and a change in its objectives. The process of the electrification of transportation, which, as a result of the current situation, may have become more challenging to implement, should also be considered.