Low Electric Field Research Articles

Optimization of energy-storage properties with low electric field applications in Ca0.5Sr0.5TiO3-based linear ceramics by establishing relaxor ferroelectrics

Given superior breakdown strength than ferroelectrics, linear dielectrics have garnered plenty of attention, yet their low polarization restricts practicability at low electric fields. Hence, a strategic approach for optimizing the energy storage performance of Ca0.5Sr0.5TiO3 ceramics by selecting 0.75 K0.5Bi0.5TiO3-0.25BiFeO3 as a modulating element to establish relaxor ferroelectrics is put forward in this study. Owing to the incorporation of 0.75 K0.5Bi0.5TiO3-0.25BiFeO3 with high polarization, the issue of low polarization in Ca0.5Sr0.5TiO3 linear ceramics is overcame. (1-x)Ca0.5Sr0.5TiO3-x(0.75 K0.5Bi0.5TiO3-0.25BiFeO3) (CST-x(KBT-BF)) ceramics reveal a conversion from linear dielectrics to relaxor ferroelectrics, accompanied by a high polarization (＞45 μC/cm2) and recoverable energy density of 3.11 J/cm3 under 180 kV/cm, along with remarkable frequency and temperature stability. Simultaneously, the stepped-up relaxor behavior and refined grain size conduce to improve the energy storage performance. CST-0.5(KBT-BF) ceramics exhibit likewise a commendable discharge power density of 18.7 MW/cm3 and an ultra-short discharge time of 46.7 ns at 80 kV/cm. This work set up a conspicuous paradigm to promote the innovation-driven development of advanced energy storage capacitors at low electric fields.

High energy storage performance under low electric fields and remarkable dielectric temperature stability in (Na0.5Bi0.5)TiO3-based lead-free ceramics

Lead-free ceramic capacitors with superior energy storage properties and dielectric temperature stability are urgent needs for pulsed power devices. However, the risk of high voltage suppresses the improvement of comprehensive performance. Thus, a novel (1-x)(0.55Na0.5Bi0.5TiO3-0.45Ba0.85Ca0.15Zr0.1Ti0.9O3)-xBi(Mg2/3Ta1/3)O3 (NBBCZT-xBMT) ceramics were successfully synthesized to address the above concerns. The addition of BMT is beneficial to maintaining high polarization strength, improving the breakdown strength and optimizing relaxor behavior. As a result, the optimum component exhibits excellent energy storage capability (Wrec = 3.05 J/cm3, η = 94.3 %) at 190 kV/cm and dielectric temperature stability (TCC ≤ ±10 % from 33 to 348 °C, tanδ ≤ 0.01 from 50 to 389 °C). Moreover, the corresponding sample maintains a variation of Wrec less than 6.7 % and η less than 1.6 % at 20–140 °C and 1–100 Hz. These results provide a novel candidate for high-performance ceramic capacitors under low electric fields.

Large piezoelectric property of Bi(Fe0.93Mn0.05Ti0.02)O3 film by constructing internal bias electric field

BiFeO3 (BFO), Mn-doped-BFO (BFMO), Ti-doped-BFO (BFTO), and (Mn,Ti)-codoped-BFO (BFMTO) thin films are fabricated on the Pt/TiO2/SiO2/Si substrates via a sol–gel method combined with spin-coating and the subsequent layer-by-layer annealing technique. Compared with BFO film, the BFMTO film exhibits the lowest leakage current density ([Formula: see text][Formula: see text]A/cm2@290[Formula: see text]kV/cm). Notably, the polarization–electric field (P–E) loop of BFMTO film exhibits a positive displacement along the x-axis due to the existence of internal bias electric field, which is in agreement with the results of the PFM phase and amplitude curves. Especially, a very prominent inverse piezoelectric constant of [Formula: see text][Formula: see text]pm/V was obtained, which overcomes other related thin films. The internal bias electric field of BFMTO film can be caused by the different work functions of the thin film and the bottom electrode, accumulation of oxygen vacancies and the formation of defect dipoles. Besides, the internal bias electric field of BFMTO film has a good stability at the same electric field after experiencing the test cycle from low electric field to high electric field (400–1900[Formula: see text]kV/cm). These results indicate that self-polarized BFMTO film can be integrated to devices without additional polarization process, and have a wide range of application in microelectromechanical systems.

Improving resistant starch content of cassava starch by pulsed electric field-assisted esterification

This study aims to investigate the effect of pulsed electric field (PEF) assisted OSA esterification treatment on the multi-scale structure and digestive properties of cassava starch and structure-digestion relationships. The degree of substitution (DS) of starch dually modified at 1.5–4.5 kV/cm was 37.6–55.3 % higher than that of starch modified by the conventional method. Compared with native starch, the resistant starch (RS) content of esterified starch treated with 3 kV/cm significantly increased by 17.13 %, whereas that of starch produced by the conventional method increased by only 5.91 %. Furthermore, assisted esterification at low electric fields (1.5–3 kV/cm) promotes ester carbonyl grafting on the surface of starch granules, increases steric hindrance and promotes the rearrangement of the amorphous regions of starch, which increases the density of the double-helical structure. These structural changes slow down starch digestion and increase the RS content. Therefore, this study presents a potential method for increasing the RS content of starch products using PEF to achieve the desired digestibility.

Computational analysis of the simultaneous application of ultrasound and electric fields in a lipid bilayer

The combined application of electric fields and ultrasonic waves has shown promise in controlling cell membrane permeability, potentially resulting in synergistic effects that can be explored in the biotechnology industry. However, further clarification on how these processes interact is still needed. The objective of the present study was to investigate the atomic-scale effects of these processes on a DPPC lipid bilayer using molecular dynamics simulations. For higher electric fields, capable of independently forming pores, the application of an ultrasonic wave in the absence of cavitation yielded no additional effects on pore formation. However, for lower electric fields, the reduction in bilayer thickness induced by the shock wave catalyzed the electroporation process, effectively shortening the mean path that water molecules must traverse to form pores. When cavitation was considered, synergistic effects were evident only if the wave alone was able to generate pores through the formation of a water nanojet. In these cases, sonoporation acted as a mean to focus the electroporation effects on the initial pore formed by the nanojet. This study contributes to a better understanding of the synergy between electric fields and ultrasonic waves and to an optimal selection of processing parameters in practical applications of these processes.

Evaluation of electrokinetic-assisted phytoremediation efficiency of dibutyl phthalate contaminated soil by maize (Zea mays L.) under different electric field intensities

The excessive accumulation of dibutyl phthalate (DBP) in soil poses a serious threat to soil ecosystems and crop safety production. Electrokinetic-assisted phytoremediation (EKPR) has been considered as a potential technology for remediating organic contaminated soils. In order to investigate the effect of different electric fields on removal efficiency of DBP, three kinds of electric fields were set up in this study (1 V·cm−1, 2 V·cm−1 and 3 V·cm−1). The results showed that 59 % of DBP in soil was removed by maize (Zea mays L.) within 20 d in low-intensity electric field (1 V·cm−1), and the accumulation of DBP in maize tissues decreased significantly compared to the non-electrified treatment group. Interestingly, it could be observed that the low-intensity electric field could maintain ion homeostasis and improve the photosynthetic efficiency of the plant, thereby relieving the inhibition of DBP on plant growth and increasing the chlorophyll content (94.1 %) of maize. However, the removal efficiency of DBP by maize decreased significantly under the medium-intensity (2 V·cm−1) and high-intensity electric field (3 V·cm−1). Moreover, the important roles of soil enzyme and rhizosphere bacterial community in low-electric field were also investigated and discussed. This study provided a new perspective for exploring the mechanism of removing DBP through EKPR.

Dielectrophoresis as an Adjunctive Technique for Fibroblast Cell Migration to Enhance Wound Closure

This study reports on DEP-based simulation and experimental validation of polystyrene (PS) beads and fibroblast cells for primary skin cell migration for enhancing wound closure. MyDEP software was used to calculate the numerical simulation of the Clausius-Mossotti factor (CMF). In order to examine particle trajectories based on input frequencies, the finite element technique (FEM) is used. The trajectories of PS beads and fibroblast cells were experimentally assessed to verify the impact of frequency applied on the polarisation of PS beads and fibroblast cells. The outcome illustrated the potential of employing FDEP to move particles and cells to regions of high and low electric field. Fibroblast cells exhibit negative dielectrophoresis (NDEP) at a broad range of frequencies. Thus, FDEP can be utilised for frequency optimisation to enhance wound closure.

Polymorphic Heterogeneous Polar Structure Enabled Superior Capacitive Energy Storage in Lead-Free Relaxor Ferroelectrics at Low Electric Field.

High-performance energy storage dielectrics capable of low/moderate field operation are vital in advanced electrical and electronic systems. However, in contrast to achievements in enhancing recoverable energy density (Wrec), the active realization of superior Wrec and energy efficiency (η) with giant energy-storage coefficient (Wrec/E) in low/moderate electric field (E) regions is much more challenging for dielectric materials. Herein, lead-free relaxor ferroelectrics are reported with giant Wrec/E designed with polymorphic heterogeneous polar structure. Following the guidance of Landau phenomenological theory and rational composition construction, the conceived (Bi0.5Na0.5)TiO3-based ternary solid solution that delivers giant Wrec/E of ≈0.0168 µCcm-2, high Wrec of ≈4.71 J cm-3 and high η of ≈93% under low E of 280kVcm-1, accompanied by great stabilities against temperature/frequency/cycling number and excellent charging-discharging properties, which is ahead of most currently reported lead-free energy storage bulk ceramics measured at same E range. Atomistic observations reveal that the correlated coexisting local rhombohedral-tetragonal polar nanoregions embedded in the cubic matrix are constructed, which enables high polarization, minimized hysteresis, and significantly delayed polarization saturation concurrently, endowing giant Wrec/E along with high Wrec and η. These findings advance the superiority and feasibility of polymorphic nanodomains in designing highly efficient capacitors for low/moderate field-region practical applications.

Structurally Regulated Design Strategy of Bi0.5Na0.5TiO3-Based Ceramics for High Energy-Storage Performance at a Low Electric Field.

Dielectric ceramic capacitors are prospective energy-storage devices for pulsed-power systems owing to their ultrafast charge-discharge speed. However, low energy-storage density makes them difficult to commercialize for high-pulse-power technology applications. Herein, we presented a structurally regulated design strategy to disrupt a long-range ferroelectric order, refined grains, and eventually achieve excellent comprehensive energy-storage performance in (1 - x) (0.7Bi0.5Na0.5TiO3-0.3SrTiO3)-x Sm(Zn2/3Nb1/3)O3 eco-friendly ceramics. A large Wrec of ∼7.43 ± 0.05 J/cm3 and a high η of ∼85 ± 0.5% of 0.96 (0.7Bi0.5Na0.5TiO3-0.3SrTiO3)-0.04 Sm(Zn2/3Nb1/3)O3 were obtained at a low electric field of 290 kV cm-1 with good energy-storage temperature (25-120 °C), frequency (1-100 Hz) stability, and charge-discharge properties (PD ∼ 74 ± 1 MW/cm3 and τ0.9 ∼ 159 ± 2 ns). This strategy inspires rational structurally regulated designs and aims to promote the development of eco-friendly 0.7Bi0.5Na0.5TiO3-based ceramics with excellent energy-storage characteristics.

The Effect of Electric Aging on Vinylidene Fluoride Copolymers for Ferroelectric Memory.

Copolymers based on vinylidene fluoride are potential materials for ferroelectric memory elements. The trend in studies showing that a decrease in the degree of crystallinity can lead to an unexpected increase in the electric breakdown field is noted. An analysis of the literature data reveals that in fluorine-containing ferroelectric polymers, when using a bipolar triangular field, the hysteresis loop has an unclosed shape, with each subsequent loop being accompanied by a decrease in the dielectric response. In this work, the effect of the structure of self-polarized films of copolymers of vinylidene fluoride with tetrafluoroethylene and hexafluoropropylene on breakdown processes was studied. The structure of the polymer films was monitored using infrared spectroscopy (IR) and X-ray diffraction. Kelvin probe force microscopy (KPFM) was applied to characterize the local electrical properties of the polymers. For the films of the first copolymer, which crystallize in the polar β-phase, asymmetry in the dielectric response was observed at fields greater than the coercive field. For the films of the copolymers of vinylidene fluoride with hexafluoropropylene, which crystallize predominantly in the nonpolar α-phase, polarization switching processes have also been observed, but at lower electric fields. The noted phenomena will help to identify the influence of the structure of ferroelectric polymers on their electrical properties.

Ferroelectric properties and current mechanisms of BaTiO3/Nb:SrTiO3 thin films

[Formula: see text] thin film oxides have been deposited on [Formula: see text] substrates using a pulsed laser deposition system. Different annealing methods were thereafter used to assess the ferroelectricity of the grown films. The residual polarization value, 2Pr, of 4.205 [Formula: see text]C/cm2 and saturated residual polarization value, 2Pmax, of 15.484 [Formula: see text]C/cm2 were obtained using in-situ annealing. After performing rapid thermal annealing (RTA) annealing, the residual polarization value rose to 4.676 [Formula: see text]C/cm2 and the saturated residual polarization value rose to 18.723 [Formula: see text]C/cm2. Furthermore, a comparison of results showed that the saturation test frequency of the in-situ annealing was 10 times higher than the saturation test frequency of the RTA. This could be explained by the fact that the secondary high-temperature annealing led to a decrease in the conductivity of the doped oxide and, thereby, a decrease in the effective electric field that was applied to both ends of the BTO ([Formula: see text]) film. Thus, a lower frequency was required to ensure a flip of all ferroelectric domains within the BTO film. By testing the fatigue frequency at 100 kHz, [Formula: see text] stable cycles in both annealing methods and the results confirmed the good stability of the device performance. A linear fit analysis of the [Formula: see text] – [Formula: see text] curves showed under in-situ annealing the presence of both a bulk-limited current mechanism that was dominated by the space charge limited current (SCLC) and Pool–Frenkel (PF) mechanisms, and an interface-limited current that was dominated by the Fowler–Nordheim (FN) mechanism in the structure. After RTA annealing, the conducting mechanism is ohmic contact at low electric field and the SCLC mechanism at high field strength. The results show that after RTA annealing, the quality and ferroelectric properties of the films are significantly improved compared to those under in-situ annealing. These results showed that the BTO/NSTO/STO ([Formula: see text]) structure had a standard test frequency as well as reliable stability. The BTO/NSTO/STO structure showed, therefore, promising applications in future nonvolatile information memory devices.

Impact of seasonal variations on low and mid-latitudes ionospheric electric field satellite measurements

Ionospheric electric field measurements are provided by the Langmuir probe onboard the DEMETER satellite. Because there are four probes, various combinations of them form double probes that yield measurements. However, only the combination of probe antennas (E3) and (E4) enables possible measurements of the ambient (natural) ionospheric electric field. For other combinations, the measured field is almost identical to the induced field resulting from satellite motion. On the basis of this, we conducted comparative studies of the measured and induced electric fields during different seasons (summer, autumn, winter, and spring) to determine the best period for ionospheric electric field measurements. Multiple orbits were selected during different periods when the satellite was exposed to solar radiation. In all seasons except winter, the profiles of the induced and measured ionospheric electric field are similar. This masking effect leads to an underestimation of the ambient electric field. However, the highest accuracy for the ambient field can be obtained during winter, when solar flux radiation is weaker than that during other seasons. The probe position and orbital altitude also play important roles in the behavior of the induced electric field.

Second-harmonic generation of ultrashort pulses in refractive index linearly modulating quantum dot structure

While other works use segments of nonlinear crystal to compensate for walk-off, this work utilizes a quantum dot (QD) nanostructure for such compensation. Such nanocrystal structures allow two benefits: the high nonlinear susceptibility in these nanocrystals and the high surface density of QDs in the structure. Good results are obtained for pre-chirping and modulation parameters. The results are computed at 10 and 100 kV/cm applied electric fields. Compared to ordinary nonlinear crystals, the pulse width, intensity, and efficiency of the second harmonic (SH) pulse are all higher in QD nanocrystals, even with a low electric field applied. Higher applied fields give higher results.

Effect of rmEGF combined with ELF-EMF on promoting wound healing in rats.

The process of wound healing is complex, and expediting it remains a challenge. The advantages of extremely low frequency electric and magnetic fields (ELF-EMF) are its non-invasive treatment, promotes healing and promotes myogenesis of C2C12 cells. Epidermal growth factor (EGF) is known to play a vital role in promoting wound healing, so a combination of ELF-EMF and EGF can have far-reaching significance. To study the effect of recombinant murine epidermal growth factor (rmEGF) combined with ELF-EMF on wound healing. Thirty-six rats were randomly divided into three groups: normal control group, EGF group, and ELF-EMF+EGF group, and a 20 mm × 20 mm dorsal wound was made. The wound healing rate of rats was calculated on the 3rd, 7th, 11th and 15th day. HE staining was used to observe the micro-morphological changes during the wound healing process. The wound healing rate of EGF+ELF-EMF group was better than other groups. On the 15th day of wound healing, the wounds of each group were completely healed. On the 3rd, 7th, 11th and 15th day of HE staining, the early inflammatory cell infiltration, the arrangement of fibroblasts and the number of new capillaries in the wounds of EGF+ELF-EMF group were better than those of the other groups. rmEGF combined with ELF-EMF significantly promotes wound healing in SD rats.

Spatial evolution of the proton-coupled Mott transition in correlated oxides for neuromorphic computing.

The proton-electron coupling effect induces rich spectrums of electronic states in correlated oxides, opening tempting opportunities for exploring novel devices with multifunctions. Here, via modest Pt-aided hydrogen spillover at room temperature, amounts of protons are introduced into SmNiO3-based devices. In situ structural characterizations together with first-principles calculation reveal that the local Mott transition is reversibly driven by migration and redistribution of the predoped protons. The accompanying giant resistance change results in excellent memristive behaviors under ultralow electric fields. Hierarchical tree-like memory states, an instinct displayed in bio-synapses, are further realized in the devices by spatially varying the proton concentration with electric pulses, showing great promise in artificial neural networks for solving intricate problems. Our research demonstrates the direct and effective control of proton evolution using extremely low electric field, offering an alternative pathway for modifying the functionalities of correlated oxides and constructing low-power consumption intelligent devices and neural network circuits.

Structural and physical properties of Pb(Zr0.4Ti0.6)O3 epitaxial film with LaNiO3 electrodes

Epitaxial LaNiO3 (LNO)/PbZr0.4Ti0.6O3 (PZT)/LaNiO3 heterostructures have been deposited on LaAlO3 (LAO) substrates, in which LNO films were prepared by magnetron sputtering and PZT films with thicknesses ranging from 40 nm to 160 nm were deposited via sol-gel method. It is found that the structural and physical properties of PZT films are closely related to the tetragonality (c/a-1). With increasing PZT thickness, both tetragonality and remanent polarization increase, and the maximum tetragonality and remanent polarization correspond to a 120-nm-thick PZT film capacitor with a remanent polarization of 61.6 μC/cm2 measured at 425.00 kV/cm. However, as the thickness of PZT film is further increased, the ferroelectric polarization decreases which is attributed to relaxation of the PZT film. The leakage current mechanism of the capacitor remains unchanged regardless of the PZT thickness. It is Space Charge Limited Current (SCLC) conduction mechanism at high electric fields and Ohmic conduction mechanism at low electric fields.

Preparation of PANI/CuPc/PDMS Composite Elastomer with High Dielectric Constant and Low Modulus Assisted by Electric Fields.

Dielectric elastomer is a kind of electronic electroactive polymer, which plays an important role in the application of soft robots and flexible electronics. In this study, an all-organic polyaniline/copper phthalocyanine/silicone rubber (PANI/CuPc/PDMS) dielectric composite with superior comprehensive properties was prepared by manipulating the arrangement of filler in a polymer matrix assisted by electric fields. Both CuPc particles and PANI particles can form network structures in the PDMS matrix by self-assembly under electric fields, which can enhance the dielectric properties of the composites at low filler content. The dielectric constant of the assembled PANI/CuPc/PDMS composites can reach up to 140 at 100 Hz when the content of CuPc and PANI particles is 4 wt% and 2.5 wt%, respectively. Moreover, the elastic modulus of the composites remains below 2 MPa, which is important for electro-deforming. The strain of assembled PANI/CuPc/PDMS three-phase composites at low electric field strength (2 kV/mm) can increase up to five times the composites with randomly dispersed particles, which makes this composite have potential application in the field of soft robots and flexible electronics.

High energy storage density achieved in BNT‐based ferroelectric translucent ceramics under low electric fields

AbstractThe development of ceramics with superior energy storage performance and transparency holds the potential to broaden their applications in various fields, including optoelectronics, energy storage devices, and transparent displays. However, designing a material that can achieve high energy density under low electric fields remains a challenge. In this work, (1−x)Bi0.5Na0.5TiO3−xBaZr0.3Ti0.7O3:0.6mol%Er3+ (abbreviated as (1−x)BNT−xBZT:0.6%Er3+) ferroelectric translucent ceramics were prepared by the conventional solid‐state reaction method. The energy storage properties of (1−x)BNT−xBZT:0.6%Er3+ are systematically investigated under low electric fields by modulating the coupling between coexisting phase structures of polar nano regions. Especially, 0.9BNT–0.1BZT:0.6%Er3+ ceramic exhibits an ultra‐high maximum polarization (Pmax = 66.3 µC/cm2), large recoverable energy storage density (Wrec = 2.95 J/cm3), total energy storage density (W = 5.75 J/cm3), and energy storage efficiency (η = 51.3%) under 190 kV/cm. The sample also exhibits excellent thermal stability (30‐150°C) and transmittance (∼28%). This work could facilitate the advancement of energy storage systems that are more efficient and cost‐effective, and also provide opportunities for the design and manufacture of novel devices.

Evaluation and SAR Analysis of Low Frequency and Broadband Electric Field Exposure Measurement Values in the Home Environment

In this study, the effective value of low-frequency (50 Hz) and high-frequency (700–2500 MHz) broadband electric field exposures was measured for 24 h in four different selected environments in a house. All the statistical values of 1000 data points recorded with two measuring devices for 24 h in each environment are calculated, the most appropriate curves are fitted to the data, and the curves are plotted by expressing their changes with respect to time. All statistical and parametric values of the density and cumulative probability functions of the curves are calculated and plotted. In broadband measurements, the broadband is divided into fifteen sub-bands, but the data are available in only six of these sub-bands. The six-layer human head model is created by using the middle frequencies of the six sub-bands used, and taking the permittivity (εr) and conductivity (σ) of each layer into consideration. The specific absorption rate (SAR) value in the brain is calculated by using the total transmission coefficient of six layers. The SAR value surrounding the head is obtained. These SAR values are interpreted by considering the Federal Communications Commission (FCC) and the Community European (CE) occupational and general public SAR limits.

Experimental research of ECW pre-ionization and assisted startup in EAST

Experimental research on the electron cyclotron wave (ECW) pre-ionization and assisted start-up was carried out systematically for the first time in EAST tokamak, which is a superconducting device with ITER-like full metal wall. Breakdown and plasma initiation at low toroidal electric fields (<0.3 V m−1) with ECW pre-ionization and startup assistance has been demonstrated. Also, the parameter domain of breakdown is significantly extended towards higher prefill gas pressure. The effect of ECW injection timing, power, toroidal injection angle on breakdown were also investigated. Injecting ECW earlier leads to an earlier breakdown and a higher plasma current ramp rate. The electron cyclotron heating (ECH) power threshold for breakdown in EAST is approximately 0.4 MW. In the range of ECH power tested in this work, higher ECH power is advantageous for achieving earlier and faster breakdown. Furthermore, the breakdown with radial ECW injection occurs earlier compared with oblique injections (co-current and counter-current). During the ECW-assisted startup, the process of burn-through is prolonged by the higher pre-filled gas pressure even though it enhances the ease of breakdown. In addition, compared to the low hybrid wave assistance, the ECW assistance has an effect in averting the generation of runaway electrons and improving the safety of device during startup. Moreover, the ECW assistance exhibits a high tolerance to the impurity and thus ensures a high ramp rate of plasma current even with a high impurity level.