High Electric Field Research Articles

Energy level engineering strategy to S-scheme BiOI0.15/α-FeOOH heterojunction with I vacancy for superior photo-Fenton catalytic tetracycline hydrochloride degradation

A novel S-scheme BiOI0.15/α-FeOOH heterojunction was fabricated by hydrolysis method, and its photo-Fenton oxidation performance was evaluated by removing antibiotics. The optimal BiOI0.15/α-FeOOH shows significantly enhanced photo-Fenton degradation activity of tetracycline hydrochloride (TC), reaching 98.2% within 10min, compared with the photocatalytic (48.1%) and Fenton (60.5%) degradation activity. The excellent degradation performance of BiOI0.15/α-FeOOH can be vested in the presence of I vacancies and S-scheme heterostructure. I vacancies could provide the enriched electron sites to foster the photo-Fenton-like activity (88.8% of BiOI0.15 and 65.5% of BiOI) and modulate the valence/conduction band positions of BiOIX to obtain S-scheme heterojunction catalyst. S-scheme heterostructure provides the high specific surface area and built-in electric field. Simulated wastewater studies and cycling experiments proof the practicability and stability of BiOI0.15/α-FeOOH.

Cold Sintered ZnO-Polystyrene (PS) Composites with Modified Interfacial Structures and Properties.

Lightweight and integrated electronic devices with high performance have become an inevitable trend in the development of power electronic systems. However, it is challenging to obtain lightweight and miniaturized varistors due to the low threshold electric field. Herein, (1 - x)ZnO-xPS composites with a high threshold electric field are prepared through a cold sintering process at 220 °C for 50 min, utilizing lightweight PS to modulate the grain boundary structures of ZnO varistors. With PS content ≤1.5 wt %, the relative densities of cold sintered composites exceed 95%. PS thin layers with a thickness of 2-10 nm are distributed at the grain boundaries of ZnO, forming the Schottky barrier, which triggers nonlinear current-voltage responses. With the addition of PS, the threshold electric field is dramatically enhanced from 135 to 2703 V·mm-1, higher than that of commercial ZnO varistors, which is further demonstrated by the electric field simulation of the Finite Element Method. The interfacial resistance obtained from impedance analysis increases with the increase of the PS content, and the activation energy of (1 - x)ZnO-xPS composites is higher than that of pure ZnO ceramics. This study provides a promising approach for the development of lightweight and cost-effective varistor materials.

Stable Millivolt Range Resistive Switching in Percolating Molybdenum Nanoparticle Networks.

To overcome the limitations of the conventional Von Neumann architecture, inspiration from the mammalian brain has led to the development of nanoscale neuromorphic networks. In the present research, molybdenum nanoparticles (NPs), which were produced by means of gas phase condensation based on magnetron sputtering, are shown to be the constituents of electrically percolating networks that exhibit stable, complex, neuron-like spiking behavior at low potentials in the millivolt range, satisfying well the requirement of low energy consumption. Characterization of the NPs using both scanning electron microscopy and scanning transmission electron microscopy revealed not only pristine shape, size, and density control of Mo NPs but also a preliminary proof of the working mechanism behind the spiking behavior due to filament formations. Furthermore, electrostatics COMSOL Multiphysics simulations of the morphology of the NPs provided evidence that the stable switching is due to the as-deposited stellate Mo NPs creating high electric field strengths, while keeping them separated, not seen before in other percolating networks based on spherical NPs. Hence, our results show the working mechanism behind switching in percolating Mo NP networks and show that they are very promising for realistic neuromorphic systems.

Nonlinear conductivity of aqueous electrolytes: Beyond the first Wien effect.

The conductivity of strong electrolytes increases under high electric fields, a nonlinear response known as the first Wien effect. Here, using molecular dynamics simulations, we show that this increase is almost suppressed in moderately concentrated aqueous electrolytes due to the alignment of the water molecules by the electric field. As a consequence of this alignment, the permittivity of water decreases and becomes anisotropic, an effect that can be measured in simulations and reproduced by a model of water molecules as dipoles. We incorporate the resulting anisotropic interactions between the ions into a stochastic density field theory and calculate ionic correlations as well as corrections to the Nernst-Einstein conductivity, which are in qualitative agreement with the numerical simulations.

Pt/β-Ga2O3 Schottky devices enabling 60 Hz half-wave rectification for power-efficient pixel display

Beta-phase gallium oxide, β-Ga2O3, in transistors and diodes has been reported due to its distinctive electrical characteristics, such as wide bandgap, low leakage current, and high breakdown electric field. However, besides such conventional basic devices, more advanced device applications using β-Ga2O3 are always necessary. Here, we report on the dynamic behavior of Pt/β-Ga2O3-based Schottky diode for power-efficient organic light emitting display (OLED). Two Schottky diodes are back-to-back connected in series to form a half-wave rectifier circuit and finally integrated with an OLED diode pixel. When AC voltage is applied to the circuit at a frequency greater than 60 Hz, blinking of the OLED light is indistinguishable to human eyes. By way of the rectifier circuit, the OLED pixel efficiently saves more than 35% of the power that should be consumed by applying DC voltage.

BIOM-14. TRANSMEMBRANE WATER EFFLUX RATE (KIO) IS AN MRI-DETECTABLE BIOMARKER TO EVALUATE THE EFFICIENCY OF TTFIELDS TREATMENT ON GLIOBLASTOMA

Abstract BACKGROUND Tumor Treating Fields (TTFields) has emerged as an effective treatment modality for Glioblastoma, shown to improve both OS and PFS. Yet how to monitor response to TTFields remains unclear. In this study, we proposed using transmembrane water efflux rate (kio), a non-invasive biomarker detectable in conventional MRI and reflecting cell membrane permeability, to assess the treatment efficiency of TTFields. METHODS U-87 MG human glioblastoma cell line were treated with TTFields at frequency of 200 kHz and varying field strengths of 0 V/cm, 0.8 V/cm, 1.2 V/cm and 1.6 V/cm using the inovitro system from Novocure. The measurement of kio was performed on a 0.5 T benchtop MRI system (Pure Devices GmbH) using a home-developed filter-exchange imaging (FEXI) sequence. Cell membrane morphology were quantitatively analysed using scanning electron microscopy. Patients with newly diagnosed glioblastoma (ndGBM) who underwent DCE-MRI before and after TTFields treatment were identified and the change of FEXI-kio value were analysed. RESULTS In the same frequency, the effect of TTFields on cancer cell proliferation is dependent on intensity, manifested a decrease in cell growth rate under high electric field intensity. As the TTFields electric field intensity increased, the cell membrane permeability (kio) also increased, exhibits a significant negative correlation with glioblastoma cell growth rate (p=0.031). Scanning electron microscopy reveals that TTFields can induce significant cell membrane pores, and the total surface area of membrane pores correlates significantly positively with FEXSY-kio index. DCE-MRI data obtained from 4 ndGBM before and after TTFields therapy showed that the FEXI-kio value is increased after TTFields treatment. CONCLUSION This study demonstrated that TTFields increases membrane permeability by inducing cell membrane holes, and kio is a promising non-invasive MRI biomarker to evaluate the efficiency of TTFields treatment.

Micro-discharge in GIS/GIL Induced by Scratch Defect on the Surface of Insulation Pull Rods

Abstract The insulation pull rod (IPR) plays a crucial role in gas insulated switchgear (GIS) and gas insulated transmission line (GIL), which must withstand high impulse voltages to cope with frequent switching operations under working conditions. During the manufacturing process, micro-defects may occur on the surface of insulation pull rods, which may cause micro-discharge or even breakdown. It is difficult to carry out experiments to study the microscopic characteristics of the micro-discharge induced by micro-defects on the surface of the insulation pull rod. In order to study the relationship between the micro-discharge and the micro-defects. Firstly, the characterization of the scratch defect based on Micro-CT (micro computed tomography) and white light interference are presented. Secondly, a coaxial DC SF6 corona discharge model is established to obtain the curve related to the density of charged particles in SF6 and the electric field. Finally, we combined the reconstruction of the defect model in the first step with the curve obtained in the second step to simulate the micro discharge around the scratch defect, and provided the micro-discharge in pure SF6 caused by the scratch defect. The phenomenon of micro-discharge induced by the scratch of insulation pull rod is explained. The oscillation phenomenon of internal micro-discharge in scratch defects under high electric field background was discovered.

Spontaneous Phase Transition and Multistage Interfacial Mechanical Friction of Liquid Metals Induced CO2 Reduction at Room Temperature

AbstractExcessive emissions of carbon dioxide (CO2) have caused the greenhouse effect and environmental crisis. Therefore, the carbon reduction and negative carbon technologies are particularly important. Among these, the negative carbon technologies that convert CO2 into carbon materials or carbon‐based chemicals for reuse have attracted significant attention. However, the strong double covalent bonds make the CO2 conversion usually require harsh conditions, complex processes, and high energy consumption. Gallium‐based liquid metals (LMs) are the functional materials with both metallic and liquid properties, exhibiting a unique liquid‐phase structure and diverse surface characteristics. Herein, a strategy for reducing CO2 is proposed to carbon materials by utilizing the spontaneous phase transition and mechanical friction of liquid metals. The gallium (Ga) and indium (In) particles are mixed and exposed to CO2, the contact interface of metal particles spontaneously transforms into liquid metals. The system has multistage interfaces, including Ga/In, Ga/eGaIn, and In/eGaIn, capable of generating triboelectrification upon mechanical stimulation, leading to charge transfer. The high electric field generated by friction at the contact interface directly reduces CO2 to carbon materials at room temperature. The carbon materials cover the surface of eGaIn and can be directly stripped for used as fuel, or industrial applications.

Analyzing negative differential resistance and capacitive effects in SiOx-based resistive switching devices for security applications

In this work, we analyze the negative differential resistance and capacitive effects in SiOx-based resistive switching devices. The cause of the negative differential effect has been investigated through the study of the switching mechanism in the devices. It has been observed that there is a combination of trap-controlled space charge limited conduction and trap-assisted Poole-Frenkel effect in the devices. Trapping and de-trapping of injected electrons in the defects within the silica structure causes the negative differential resistance effect. This characteristic feature can be employed to design chaotic circuits for security applications. In addition, the high electric field developed in the device compared to the applied field during the change of bias voltage from ±5V–0V, results in a capacitor discharge-like effect. This work will be a step forward in achieving the global Sustainable Development Goal of Peace, Justice, and Strong Institutions (SDG 16).

Plasma Treatment Technologies for GaN Electronics

Nowadays, the third-generation semiconductor led by GaN has brought great changes to the semiconductor industry. Utilizing its characteristics of a wide bandgap, high breakdown Electric field, and high electron mobility, GaN material is widely applied in areas such as 5G communication and electric vehicles to improve energy conservation and reduce emissions. However, with the progress in the development of GaN electronics, surface and interface defects have become a main problem that limits the further promotion of their performance and stability, increasing leakage current and causing degradation in breakdown voltage. Thus, to reduce the damage, Plasma treatment technologies are introduced in the fabrication process of GaN electronics. Up to now, designs like the high-resistivity p-GaN cap Layer, passivating termination, and surface recovery process have been established via Plasma treatment, reaching the goals of normally-off transistors, diodes with high breakdown voltage and high-reliability GaN electronics, etc. In this article, hydrogen, fluorine, oxygen, and nitrogen Plasma treatment technologies will be discussed, and their application in GaN electronics will be reviewed and compared.

Effects of A-site configuration entropy on the dielectric properties in tetragonal tungsten bronze ceramics

A series of Sr4.5Ca0.5MTi3Nb7O30 [M = La0.5Nd0.5 (LN), La1/3Nd1/3Sm1/3 (LNS) and La0.25Nd0.25Sm0.25Eu0.25 (LNSE)] ceramics with different A-site configuration entropy were prepared, and the effects of the A-site configuration entropy on the dielectric and ferroelectric properties were investigated. Due to the combined effect of high entropy and solid solution, the best dielectric performance was achieved in the LNS composition, where the dielectric constant remained around 650 in the temperature range of 269–515 K with a change rate of less than 15%. Under the DC high voltage field up to 67 kV/cm, each component's polarization characteristics and dielectric constants obtained good electric field stability and temperature stability under a high electric field.

Nano‐Patterned CuO Nanowire Nanogap Hydrogen Gas Sensor with Voids

AbstractHydrogen (H2) is increasingly employed in industrial applications, such as developing hydrogen fuel cells for vehicles and power plants. However, H2 explodes at a concentration limit of 4%, necessitating the development of ultrasensitive hydrogen sensors capable of early‐stage detection of hydrogen leaks. In this study, nano‐patterned polycrystalline cupric oxide (CuO) nanowire array nanogap gas sensors with voids are fabricated using electron‐beam lithography and ex situ oxidization by annealing, which could detect 5 ppb H2 and show response and recovery times of less than 10 s without a baseline shift. Combining a pre‐H2 annealing process in Ar/H2 for Cu nanowires and a low‐rate oxidation process enhances the crystallinity of CuO nanowires, facilitating the preparation of polycrystalline CuO nanowires with voids, which is a significantly practical approach for the improvements of gas sensing properties. Response and recovery times of <10 s can be obtained for a gap separation of ≈30 nm. These improvements are discussed based on a high electric field of ≈1.3 MV cm−1. The relationship between the normalized response and H2 concentration is discussed based on the power law. This paper presents highly reliable and fast H2 sensors without a baseline shift to meet the demands of the hydrogen industry.

Effect of alkali metal sulfates on hydration properties of alpha-calcium sulfate hemihydrate for 3D printing

Three-dimensional printing (3DP) technology is an important means of achieving decorative convenience, personalization, and functional integration for future building construction. However, the setting time and hydration process of calcium sulfate hemihydrate (HH) present chanllenges for the 3DP application. This study aims to investigate the accelerating effect of alkali metal sulfates accelerators on the hydration transformation of HH into calcium sulfate dihydrate (DH). The setting time, conductivity, Ca2+ ion concentration, size distribution, and zeta (ζ) potential of gypsum slurries with different accelerators were measured. The results demonstrated that the accelerators significantly enhanced the hydration process of αlpha-calcium sulfate hemihydrate (α-HH). On the effect of accelerators, the setting times of gypsum slurries containing 30 wt% lithium sulfate (LS), sodium sulfate (NS) and potassium sulfate (KS) were accelerated by 82.56 %, 86.06 % and 97.13 %, respectively, compared to the control sample. The crystal particle sizes of hydration products decreased, and the absolute values of ζ potential increased to 1.85 mV, 3.1 mV, and 5.3 mV, respectively. The X-ray photoelectron spectroscopy (XPS) analysis revealed a shift in the peak values of the hardened specimens towards higher electric fields. This was accompanied by improved ion dispersion within the slurry, resulting in enhanced supersaturation of calcium sulfate dihydrate and crystallization of the crystal nuclei. Thus, the suitable accelerators can effectively achieve rapid solidification and hardening of high-fluidity gypsum slurries.

Variable‐Range Hopping Conduction in Amorphous, Non‐Stoichiometric Gallium Oxide

AbstractAmorphous, non‐stoichiometric gallium oxide (a‐GaOx, x < 1.5) is a promising material for many electronic devices, such as resistive switching memories, neuromorphic circuits and photodetectors. So far, all respective measurements are interpreted with the explicit or implicit assumption of n‐type band transport above the conduction band mobility edge. In this study, the experimental and theoretical results consistently show for the first time that for an O/Ga ratio x of 0.8 to 1.0 the dominating electron transport mechanism is, however, variable‐range hopping (VRH) between localized states, even at room temperature and above. The measured conductivity exhibits the characteristic exponential temperature dependence on T−1/4, in remarkable agreement with Mott's iconic law for VRH. Localized states near the Fermi level are confirmed by photoelectron spectroscopy and density of states (DOS) calculations. The experimental conductivity data is reproduced quantitatively by kinetic Monte Carlo (KMC) simulations of the VRH mechanism, based on the ab‐initio DOS. High electric field strengths F cause elevated electron temperatures and an exponential increase of the conductivity with F1/2. Novel results concerning surface oxidation, magnetoresistance, Hall effect, thermopower and electron diffusion are also reported. The findings lead to a new understanding of a‐GaOx devices, also with regard to metal|a‐GaOx Schottky barriers.

Ultra–fast plastic forming of zirconia ceramics under a low temperature and high electric field

The low–temperature plastic forming ability of ceramics with complex structures is unsatisfied due to the strong covalent and ionic bonds, restricting their widespread applications. Herein, a technique is proposed for the ultra–fast plastic forming of zirconia ceramics using a low temperature and high electric field. The high electric field–assisted plastic forming temperature and rate are 1000 °C and 10mm/min, respectively, which are much lower and faster than those of conventional plastic forming methods for ceramics. The deformed “Ω”–shape zirconia part exhibits a uniform microstructure without microcracks/cavities and a high hardness, demonstrating that the high electric field–assisted plastic forming technique enables the rapid fabrication of complex ceramic components with beneficial properties at low temperatures.

Ohmic pasteurization of probiotic chocolate dairy desserts and its quality attributes

The study evaluated the effects of conventional pasteurization and ohmic heating (OH) at different electric fields (12, 16, 20, or 24 V/cm−1) on probiotic chocolate dairy desserts’ physicochemical, microbiological, sensory properties and volatile profiles. Both treatments were analyzed for parameters such as pH, syneresis, cream stability index, rheology, bioactive compounds (total phenolics and antioxidant capacity), and probiotic viability (Lactobacillus acidophilus LA-05) over a 28-day storage period. Ohmic heating at higher electric fields (20 and 24 V/cm−1) showed comparable results to pasteurization for most parameters, with non-significant differences or even higher values for some. Sensory analysis revealed that pasteurized samples were more associated with “creamy” and “firm” textures. In contrast, OH-treated samples were linked to lumps and fluidity, particularly in OH24 and OH16, respectively. Volatile compounds such as propanal and ethyl propanoate were detected across treatments, with ethyl acetate unique to OH24. The results suggest that OH, especially at higher electric fields, is a promising technology for processing probiotic dairy desserts, offering similar or enhanced qualities compared to conventional pasteurization. These findings provide insights into the potential for OH to be routinely applied in functional dairy product production.

Some features of experimental determination of localization length of charges in carbon nanomaterials for positive and negative magnetoresistance

This paper discusses features of experimental determination of localization lengths of charge carriers in carbon-based nanomaterials for the cases of positive and negative magnetoresistance in the hopping conduction regime. Magnetoresistance at a temperature of 4.2 K in reduced graphene oxide (RGO) and ternary nanocomposite PVDF/PANI/MWCNT film based on polyaniline (PANI, 4.8 wt%) and multi-walled carbon nanotubes (MWCNT, 10 wt%) distributed in the dielectric matrix of polyvinylidene fluoride (PVDF) was studied. The studied samples RGO and PVDF/PANI/MWCNT show positive and negative magnetoresistance, respectively. It is shown that in sufficiently weak magnetic fields, positive and negative magnetoresistances show a quadratic dependence on the applied field. The charge carrier localization length estimated from conductivity in weak magnetic fields agrees with data obtained in high electric fields without magnetic field.

Achieving an appropriate polarization-breakdown synergy of multilayer films for dielectric energy storage through temperature gradient annealing

Large polarization and high breakdown strength are the key to achieving an idea energy storage density in dielectric capacitors, but unfortunately the trade-off problem between them is difficult to evade, particularly for those dielectrics with different crystalline degrees. Herein, we propose an appropriate polarization-breakdown synergistic strategy of dielectric multilayer films through temperature gradient annealing. The dielectric properties of a serials of (Pb, La)(Zr, Ti)O3/SrTiO3/(Pb, La)(Zr, Ti)O3 (PLZT/STO/PLZT) structures with different annealing temperature for each layer are compared. The optimum recoverable energy density of 57.9 J/cm3 is achieved at a high breakdown electric field of 5.78 MV/cm and a moderate maximum polarization of 22.5 μC/cm2. In addition to the role of suppressing the carriers transport of interlayer STO, the balance between polarization and breakdown strength in bottom and top PLZT layers with individual dielectric characteristics should be responsible for the enhanced energy storage performance (ESP). The results suggest that it is a feasible way to optimize the ESP of dielectric multilayer films through designing different stacking layer via temperature gradient annealing heat treatment.

Self-powered wireless sensing system with cylindrical high voltage side electric field energy harvesting by discharge circuit

To warn of overcurrent heating, temperature wireless sensor node (WSN) need to be deployed on the overhead lines of the power grid. The sustainable power supply of WSN is difficult. Using the electric field energy around the transmission line to power the sensor has the advantages of stability, reliability and sustainability, but the electric field energy harvesting (EFEH) power need to be improved. This paper studies the principle of energy harvesting by displacement current and discharge method, and analyzes the influencing factors of the output power of the EFEH unit. The power improvement method of the EFEH unit is proposed by improving the coupling capacitor and the energy storage capacity discharge voltage. The relationship between the structural parameters of energy cylinder and induced potential and coupling capacitance is explored by COMSOL simulation software. A low-cost, self-driven and adjustable high voltage undervoltage lock (UVLO) circuit is proposed. A 10kV high voltage generation platform is built in the laboratory, and the wireless temperature and humidity sensor is self-powered by the EFEH with power of 2.04mW. This research has important theoretical and application value for the high voltage side EFEH powered WSN.

Investigating the effect of finite ionic size and solvent polarization on induced charge electro-osmosis around a perfectly polarizable cylinder

Many industrially relevant microfluidic applications use concentrated solutions of macro-molecular solutes dissolved in polar solvents like water, which are typically deployed at high voltages. In this study, we investigate the effect of finite ionic sizes and solvent polarization on induced charge electro-osmotic flow around a perfectly polarizable cylinder, at high electric field strengths and ionic concentrations. The flow is actuated by means of a direct current electric field, and the step response of various flow parameters are studied numerically. Finite ionic sizes, defined through a steric factor ν, are modeled using the modified Poisson–Nernst–Planck model. Additionally, a field-dependent permittivity, characterized by a solvent polarization number A, accounts for molecular re-orientation effects. Our findings reveal an ion-size modulated decrement in charge concentration in the electrical double layer and an augmentation in the electric field. Remarkably, the resulting flow velocities increase with ion size. Solvent polarization, on the other hand, results in a marked reduction in flow velocities. Steric effects, however, dominate over a large range of parameter space (applied voltage and bulk ionic concentration) as compared to solvent polarization. Finally, we demonstrate that unequal ionic sizes result in flow asymmetries at the steady-state, thereby generating net electro-phoretic motion of suspended particles.