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In this work, we present an experimental study of the primary and secondary relaxations of the semi-crystalline polymer polyethylene naphthalate by modulated differential scanning calorimetry, Thermally Stimulated Depolarization Currents (TSDCs), and Broadband Dielectric Spectroscopy (BDS) and how they are affected by physical aging. Three dipolar relaxation modes can be observed: from slowest to fastest: the primary α relaxation, which vitrifies at the glass transition temperature, Tgα, and two secondary relaxations, named β* and β. Modulated differential scanning calorimetry results show how the secondary β* relaxation also vitrifies, giving rise to an additional glass transition at Tgβ* < Tgα. In fact, the α and β* relaxations can be considered as part of a very broad and distributed relaxation. Its main part is the primary α relaxation with a shoulder at the high-frequency region corresponding to a complex secondary β* relaxation. BDS results about β* can be modeled by a main contribution (β3*) and two additional ones (β1* and β2*) with a weaker dielectric strength. TSDC results show that each single mode of the relaxation has its own glass transition temperature and they are compatible with the structure inferred by BDS. This scenario gives rise to an extended glass transition dually centered in the Tgβ* ∼ 305 K and Tgα ∼ 387 K temperatures. [ABSTRACT FROM AUTHOR]

Amorphous composite polymers are widely used as insulators in microelectronics due to their high dielectric strength, mechanical robustness, and thermal stability. However, organic–inorganic composite systems suffer from undesirable performance and accelerated degradation due to leakage current ( J Tot ). Unfortunately, the underlying mechanism of J Tot and its components (e.g., ionic and electronic constituents) are inadequately understood, particularly in extreme use conditions (e.g., high humidity and temperature). In this study, we use numerical simulation and experimental J Tot data (in amorphous epoxy polymer with silica fillers) to (i) unify the electrostatic model for J Tot in composite polymers, (ii) illustrate that the early part of J Tot (i.e., external current) is primarily due to the image charge associated with ion transport/ localization ( J ion ) near the metallic contacts, (iii) demonstrate that the accumulated counter-ions reduce the barrier for electronic charge injection (by band bending) and facilitate electronic injection from the metals ( J elec ), and (iv) provide an algorithm for the in situ ion transport characterization of composite insulators by exploiting J ion . This work provides new insights regarding the leakage current mechanism and how it can be used as a probe into the complex transport mechanisms of the composite material. [ABSTRACT FROM AUTHOR]

NaNbO 3 (NN)-based lead-free dielectric ceramics exhibit great energy storage density and environmental friendliness, making them attractive options for use in pulse power capacitors. Herein, novel NN-based ceramics, namely, 0.7Na 1-3 x Sm x NbO 3 -0.3(Sr 0.7 Bi 0.2)(Ti 0.8 Zr 0.2)O 3 , were designed via composition modification in order to improve recyclable energy storage density (W rec), dielectric breakdown strength (E b), and charge-discharge rate. The phase composition, microstructure, dielectric performances and energy storage performances of the resultant ceramics were methodically studied. Ultimately, a large E b of 380 kV/cm and a great W rec of 3.2 J/cm3 were attained by the NN-SBTZ-0.01Sm ceramic. In addition, NN-SBTZ-0.01Sm ceramic exhibited outstanding temperature and frequency stabilities, which facilitated the application of dielectric capacitors. Meanwhile, high current density (C D = 268 A/cm2), and ultrafast discharge rate (t 0.9 = 35 ns) made NN-SBTZ-0.01Sm ceramic have potential applications in pulse power systems. [ABSTRACT FROM AUTHOR]

This present study investigates an eco-friendly electromagnetic interference (EMI) shielding material developed using cellulosic fiber and apple peel extracted biocarbon for safe electronic applications. The primary aim is to study how the biomass derived biocarbon influences in the wave shielding phenomenon. The fiber and filler both used from waste biomass which promotes circular economy and amine functionalization on both fiber and filler brings the novelty to this research. Further, the prepared composite under hand layup process is further assessed as per ASTM standards. Results revealed that due to the addition of surface modified cellulosic fiber and even dispersion of biochar particle into composite enhance mechanical, dielectric, EMI shielding effectiveness of the composite material. Thus, when compared to the plain vinyl ester resin (V), the amine functionalized cellulosic fiber reinforced composite material (V0) shows improved tensile, flexural and impact strength of 125 MPa, 151 MPa, and 4.1 J respectively. Further, the addition of biochar particle of 3 vol.% into the composite (V2) shows improved hydrophobicity behavior of 107° contact angle and the composite V2 further enhanced the tensile, flexural, impact strength of the composite of 145 MPa, 189 MPa, 5.1 J respectively. Moreover, the increase in biochar of 5 vol.% in to the composite (V3) shows effective dielectric loss of 0.28 in E band and 0.45 in J band. Furthermore, the composite under (V2) of 40 vol.% fiber, and 3 vol.% biochar shows maximum EMI shielding effectiveness of 8 dB in E band and 40 dB in J band, when compared to the 40 vol.% of fiber reinforced composite (V0) of EMI shielding effectiveness 9 dB in E band and 55 dB in J band respectively. Thus, this effective EMI shielding effectiveness, dielectric strength and load carrying capacity, impact strength and cost effective, light weight nature makes the composite material to be utilized in high signal protection applications, sensor, navigational devices, and various electric and electronic gadgets, etc. [ABSTRACT FROM AUTHOR]

Highlights Tailoring the interfacial structure is a critical approach for modulating the dielectric characteristics of nanocomposites. Herein, the energy storage properties of polyimide/silica (PIS) were improved by grafting 4‐carboxyphenyl (PhCOOH), 4‐aminophenyl, isocyanate, phenyl and amino groups on the interfaces. The results demonstrated that the PhCOOH groups not only optimized the interfacial structures, but also enhanced both the relative dielectric permittivity (εr) and dielectric strength (Eb) of PI‐based films. The PhCOOH endowed the PI‐based films with high εr by elevating the intrinsic polarization and suppressing the relaxation polarization. Moreover, the PhCOOH elevated charge injection barriers and reduced carrier hopping distances, resulting in a lower current density. Molecular simulations revealed that the PhCOOH raised the SiO2 electron affinity and the trap depth of PIS composites, achieving the enhancement of Eb. The PIS‐PhCOOH films with high εr (7.57, 103 Hz) and Eb (421 kV⋅mm−1) exhibited superior discharge energy density (6.20 J⋅cm−3) and energy storage efficiency (88.80%), which was 119.08% higher than that of PIS (2.83 J⋅cm−3, 75.91%). This work provides insights into interface engineering to synergistically improve dielectric permittivity and dielectric strength of polymer‐based composites, paving the way for fabricating high‐performance dielectrics. Polarization response were modulated by interface modification. Both permittivity and dielectric strength of PI‐based films were enhanced. PI‐based films showed an energy density as high as 6.20 J⋅cm−3. [ABSTRACT FROM AUTHOR]

Organometal halide perovskite (OHP) composites are flexible and easy to synthesize, making them ideal for ambient mechanical energy harvesting. Yet, the output current density from the piezoelectric nanogenerators (PENGs) remains orders of magnitude lower than their ceramic counterparts. In prior composites, high permittivity nanoparticles enhance the dielectric constant (ϵr) but reduce the dielectric strength (Eb). This guides our design: increase the dielectric constant by the high ϵr nanoparticle while enhancing the Eb by optimizing the perovskite structure. Therefore, we chemically functionalize the nanoparticles to suppress their electrically triggered ion migration for an improved piezoelectric response. The polystyrene functionalizes with FAPbBr2I enlarges the grains, homogenizes the halide ions, and maintains their structural integrity inside a polymer. Consequently, the PENG produces a current density of 2.6 µAcm−2N−1. The intercalated electrodes boost the current density to 25 µAcm−2N−1, an order of magnitude enhancement for OHP composites, and higher than ceramic composites. By functionalizing polystyrene with perovskite FAPbBr2I, both the dielectric constant and dielectric strength are controlled, leading to energy-dense composite films for piezoelectric nanogenerators with normalized current density of 25 µA.cm−2 N−1 [ABSTRACT FROM AUTHOR]

To improve the dielectric strength in vacuum, spark conditioning through repetitive breakdowns by AC or impulse voltage is an effective method. AC conditioning at commercial power frequencies has been widely used due to its cost‐effectiveness, but the breakdown voltage after AC conditioning is generally lower compared to impulse conditioning. We have confirmed that multiple breakdowns occur successively in a half cycle of AC voltage application. It is considered that the multiple breakdowns are harmful for conditioning and triggered due to the previous breakdown in the same half cycle. In this paper, we discuss dielectric strength improvement by high frequency AC conditioning and how the multiple breakdowns are induced. We experimentally confirmed that the AC conditioning effect is improved by increasing the frequency of AC voltage for different applied AC conditioning voltages in a sphere‐plane electrode system. We focused on the breakdown position from the light emission images during AC conditioning to investigate whether the multiple breakdowns were induced or affected by the previous breakdown. We found that the multiple breakdowns occurred close to the previous breakdown position. The multiple breakdowns would be induced by the collision of metal particles due to the previous breakdown with the counter electrode. These breakdowns do not contribute to removing protrusion and would lead to damage to the electrode surface. The increasing frequency of AC conditioning would suppress the multiple breakdowns and improve the dielectric strength in vacuum. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Dielectric capacitors play an increasingly important role in modern electronic power systems due to their ultrahigh charging and discharging speeds and power density. Much research has focused on enhancing dielectric breakdown strength to achieve better energy storage performance; however, this increases the potential for heat generation and unexpected insulation failures, thereby affecting the stability and lifespan of devices. This study introduces a small amount of Na+ dopants at the A-site of BaTiO 3 , inducing lattice distortions and enhancing local polarization to increase energy storage density rather than through enhancing breakdown strength. The introduction of Na+ enhances the ferroelectric properties, with polar nano-regions (PNRs) gradually evolving into long-range ordered large domains. In the Ba 0.985 Na 0.015 TiO 3 films, the coexistence and coupling of abundant PNRs with a few long-range ordered ferroelectric domains result in high saturation polarization and low residual polarization. At a moderate electric field of 2.3 MV cm−1, an ultrahigh energy density of 44.3 J cm−3 and a high energy storage efficiency of 78.6 % were obtained. Additionally, the film exhibits excellent frequency stability (100 Hz-20 kHz), temperature stability (30–180 °C), fatigue resistance (107 cycles), and high pulsed discharge energy density, along with great thermal stability. This work provides new insights into achieving exceptional energy storage performance in single-phase films. [ABSTRACT FROM AUTHOR]

Grain size pays a crucial role in the properties of ferroelectrics and dielectrics. Reducing the grain size is considered to be an effective mean for enhancing dielectric energy storage. In this work, high recovered energy storage density and efficiency were achieved in three-layered Aurivillius thin films by ultra-fine grain nano-crystalline engineering. The ultra-low remanent polarization can be attributed to the emergence of polar nano-regions due to the disruption of macroscopic continuity of ferroelectric domains by ultra-fine nano-grains. At the same time, all thin films have high dielectric breakdown strength due to the presence of extremely high grain boundary density. Thus, a high recovered energy storage density of 71 J/cm3 and an efficiency of 76% were achieved, and the thin film capacitors show good fatigue endurance and temperature stability. The results suggest that ultra-fine nano-crystalline engineering can expand the application of traditional ferroelectric thin films in energy storage devices. [ABSTRACT FROM AUTHOR]

Due to its superior reliability and performance, thick film technology is extensively employed in various applications, including automotive electronics, consumer electronics, communication engineering, and aerospace. However, a challenge arises from the mutual diffusion during the electronic paste production process, which leads to a decline in insulation performance and hinders the production of three-dimensional equipment. Inspired by the principles of low-temperature co-fired ceramic technology, a multi-layered ceramic structure has been successfully bonded using thick film technology by introducing a borosilicate glass-ceramics layer. To further enhance the properties of this multi-layered ceramic structure, approximately 8 wt% SiO 2 was incorporated into the borosilicate glass-ceramics. This addition effectively inhibits silver diffusion and reduces the diffusion depth within the glass-ceramic film. The key mechanisms behind this improvement are the increased activation energy for crystallization, resulting in a slower crystallization rate due to the addition of SiO 2. Moreover, the multi-layered ceramic with a sandwich structure exhibits remarkable properties. Notably, the dielectric strength of this system has been significantly enhanced to 13.9 kV/mm, accompanied by a high adhesion strength of 790 N. These enhanced properties of the optimized system indicate promising characteristics for multi-layer circuit applications. [ABSTRACT FROM AUTHOR]

A gaseous mixture of CO2 and C5F10O has been widely investigated as one of the alternative gases for SF6. Due to the better electron attachment ability of oxygen molecule O2, it is generally expected that adding of O2 gas would improve the dielectric strength of arc quenching and insulating gas for electric power equipment. Therefore, in this paper, the dielectric breakdown properties of hot CO2/O2/C5F10O gas mixture were numerically estimated. The calculation results revealed that the critical electric field strength of the CO2/C5F10O gas mixture is disappointingly decreased by the addition of O2 gas, especially in the temperature range of 3000 K to 1000 K. This is brought about by the increase of ionization reaction of CO2 molecules with an increase in the O2 concentration in the arc‐quenching gas of CO2/O2/C5F10O. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Ceramic-based back covers are commercially utilized as a high-end option for the physical protection of mobile phones. Herein, an unprecedented composite structure consisting of a cordierite (2MgO.2Al 2 O 3 5SiO 2) glass–ceramic strengthened with yttria-stabilized zirconia (YSZ) fillers is introduced as a protective back cover, specifically for next-generation communication mobile phones additionally requiring a low dielectric constant at gigahertz frequencies. Crystallization sequence was rather complicated with the involvements of multiple crystalline phases, α- and μ-cordierite, tetragonal and monoclinic ZrO 2 , and ZrSiO 4 , depending on the glass and composite compositions. This unique approach effectively induced the best mechanical performance for the 10 wt% YSZ/glass–ceramic structure, despite the low sintering temperature of 1050 °C, with the highest Vickers hardness of ∼9.2 GPa and flexural strength of ∼196.8 MPa attained for the optimal composite. Although effective dielectric constant of the composites depended on the relative contents of the evolved crystalline phases, overall dielectric constant was kept low due to the utilization of cordierite glass as the main component. [ABSTRACT FROM AUTHOR]

This research investigates the synthesis and evaluation of cyclic olefin copolymer (COC) composites with surface‐engineered boron nitride nanosheets (BNNs) at various concentrations. The study focuses on the impact of Cetyltrimethylammonium bromide (CTAB) on BNNs′ surface functionalization to improve their dispersion within the COC matrix, including its dielectric behavior, dielectric breakdown strength, thermal management capabilities, hygroscopic properties, and mechanical robustness. The methodological approach adopted for the fabrication of COC/BNNs hybrid composites commenced with the synthesis of BNNs, surface functionalization of BNNs, in‐situ mixing and hot‐press. This step aimed to enhance compatibility and adhesion between BNNs and the COC matrix, facilitating more homogeneous nanofiller dispersion. The investigative scope of this study encompassed a rigorous evaluation of the resultant composites, with a particular emphasis on their dielectric properties. The dielectric constant (ϵ′) and loss tangent (δ) were measured at a frequency of 10 GHz, revealing an ultra‐low dielectric constant of 1.28, an exceptionally minimal loss tangent of 0.000146, a remarkable 327% (In‐plane) & 129% (axial) increase of thermal conductivity, significant improvement of dielectric breakdown strength up to 88.4 mV/mm, and low water absorptions observed. These results indicate the potential of COC/BNNs composites for high‐frequency electronic packaging applications requiring low dielectric constants. [ABSTRACT FROM AUTHOR]

Titanite CaTiSiO 5 (CTS) is considered to be a promising dielectric material for preparing high-voltage multilayer ceramic capacitors because it exhibits a positive bias dependence of the dielectric permittivity due to its antipolar crystal structure. In this study, we investigated the dielectric response and breakdown strength of CaTiGeO 5 (CTG), a structural analog of CTS, inspired by its higher low-field dielectric permittivity. Particular attention was paid to the sintering temperature to reveal the effect of the microstructure and loss of volatile Ge on the electrical properties of CTG. Dense CTG ceramics with relative densities above 97 % and grain sizes between 1.3 and 3.4 μm were obtained through a conventional solid-state reaction route at sintering temperatures between 1150 and 1250 °C. A secondary phase of CaTiO 3 was formed in the ceramics sintered at 1200 and 1250 °C due to Ge loss, but this phase was easily removed by surface polishing alone. The sintering temperature largely affected the dielectric breakdown strength through microstructural development, resulting in the highest breakdown strength of 1190 kV cm−1 for a sample sintered at 1200 °C, while it did not change the low-field dielectric properties of the samples. Furthermore, the sample retained high breakdown strength of >900 kV cm−1 at elevated temperatures up to 150 °C and exhibited a nonlinear polarization response, resulting in the positive electric field dependence of the dielectric permittivity. [ABSTRACT FROM AUTHOR]

The overall performance of 3D printed epoxy resin falls short of meeting the demands for the production and advancement of insulating components in electrified transportation equipment. This article introduces an approach for enhancing the dielectric characteristics of a composite epoxy resin oriented with hexagonal boron nitride by incorporating nano-alumina. Consequently, a 3D printed composite epoxy resin comprising nano-alumina and hexagonal boron nitride is successfully fabricated, demonstrating exceptional physical, chemical, and dielectric properties. The research findings unveil that, when the filler content reaches 3 wt% for nano-alumina and 27 wt% for hexagonal boron nitride, the micro-nano composite epoxy resin exhibits impressive mechanical characteristics while maintaining a significant degree of thermally conductive anisotropy. Specifically, at this precise filler content, the interlayer compatibility within the micro-nano composite epoxy resin experiences a substantial improvement, ultimately resulting in outstanding dielectric performance with a maximum volume resistivity of 5.5 × 1015 Ω∙cm and a surface resistivity of approximately 6.2 × 1014 Ω. Furthermore, the micro-nano composite epoxy resin, with in-plane-oriented hBN, exhibits the highest dielectric strength, achieving a peak value of 35.7 kV∙mm−1 at the mentioned filler content. This investigation offers valuable insights into the development of high-performance 3D printed insulation components. [ABSTRACT FROM AUTHOR]

Porous Si 3 N 4 ceramics were fabricated via pressureless sintering employing ternary lithium oxides (LiScO 2 , LiYO 2 , LiYbO 2) derived from various Re 2 O 3 as sintering additives under nitrogen atmosphere at the temperature of 1400–1700 °C. The study studied how sintering temperatures andternary lithium oxide additives affect the phase, microstructure, and material properties of Si 3 N 4. The results show that as the amount of sintering aids increases, the bulk density of samples increases. At the same time, the apparent porosity diminishes, leading to enhancements in flexure strength and dielectric constant. The Si 3 N 4 -based porous ceramic sample containing 5 wt% LiYbO 2 sintered at 1600 °C exhibits a volumetric weight of 1.828 g/cm3, an apparent porosity of 35.14 %, an average flexure strength of 114.8 MPa, a dielectric constant of 3.95, a loss tangent of 5.457 × 10−3, and a low thermal conductivity of 8.241, offering insights into the preparation of radome materials. [ABSTRACT FROM AUTHOR]

Functional nanocomposite-based printable inks impart strength, mechanical stability, and bioactivity to the printed matrix due to the presence of nanomaterials or nanostructures. Carbonaceous nanomaterials are known to improve the electrical conductivity, osteoconductivity, mechanical, and thermal properties of printed materials. In the current work, we have incorporated carbon nanofiber nanoparticles (CNF NPs) into methacrylated gelatin (GelMA) to investigate whether the resulting nanocomposite printable ink constructs (GelMA-CNF NPs) promote cell proliferation. Two kinds of printable constructs, cell-laden bioink and biomaterial ink, were prepared by incorporating various concentrations of CNF NPs (50, 100, and 150 µg/mL). The CNF NPs improved the mechanical strength and dielectric properties of the printed constructs. The in vitro cell line studies using normal human dermal fibroblasts (nHDF) demonstrated that CNF NPs are involved in cell-material interaction without affecting cellular morphology. Though the presence of NPs did not affect cellular viability on the initial days of treatment, it caused cytotoxicity to the cells on days 4 and 7 of the treatment. A significant level of cytotoxicity was observed in the highly CNF-concentrated bioink scaffolds (100 and 150 µg/mL). The unfavorable outcomes of the current work necessitate further study of employing functionalized CNF NPs to achieve enhanced cell proliferation in GelMA-CNF NPs-based bioprinted constructs and advance the application of skin tissue regeneration. [ABSTRACT FROM AUTHOR]

We studied the transport properties of graphene–insulator–metal tunneling diodes. Two sets of tunneling diodes with Ti–Cu and Cr–Au top contacts are fabricated. Transport measurements showed state-of-the-art non-linearity and a critical influence of the top metals on the dielectric strength of the tunneling barrier. X-ray photoelectron spectroscopy indicated two methods for enhancing the dielectric strength of the tunneling barrier. These are the optimized seed layers for the growth of high-quality conformal insulators and the selection of appropriate top metal layers with a small diffusion coefficient and electromigration into the Al2O3 barrier. The Cr–Au top contact provides superior characteristics to the Ti–Cu metallization. X-ray photoelectron spectroscopy showed significant diffusion of titanium during the Al2O3 growth and the formation of titanium inclusions after annealing. Chromium diffusion is slower than that of titanium, making chromium contact more suitable for the reliable operation of tunneling diodes. As a result, we demonstrate a 40% improvement in the dielectric strength of the tunneling barrier compared to state-of-the-art metal–insulator–metal diodes. [ABSTRACT FROM AUTHOR]

Simple Summary: Electrocutions on power lines are killing birds world-wide and causing population-level effects in some species. Distribution pylons constructed of grounded materials like steel are particularly dangerous because separations between the energized and grounded components are minimal, so even small birds can be electrocuted. To explore a potential mitigation measure for steel crossarms, we coated them in glass flake epoxy (GFE), a relatively non-conductive material. We then installed coated crossarms on a line known to have frequent faults (leaking electrical power), where many of the faults had previously been implicated in avian electrocutions. Thus, we used faults as a proxy for electrocutions. We found that replacement of 24% of untreated crossarms (crossarms without epoxy coating) with GFE-coated crossarms correlated temporally with a 28% decrease in faults in a 20 kV distribution line. The decreased fault rate was particularly stark during the avian breeding season when birds can be particularly vulnerable to electrocution, supporting our use of faults as a proxy for electrocution risk. Future research should evaluate electrocution risk directly without using faults as proxies. Nevertheless, GFE coatings have potential conservation benefits on grounded pylons but require additional research to avoid the use of faults as proxies, and to confirm long-term durability and effectiveness. Electrical faults caused by power escaping electric systems can lead to power outages, equipment damage, and fires. Faults sometimes occur when birds perched on power structures are electrocuted. Distribution power lines supported by concrete and steel pylons are particularly fault-prone because small separations between conductors and grounded components allow even small birds to inadvertently create faults while being electrocuted. Most conservation solutions focus on covering energized wires and components to prevent contact by birds and, although usually effective when installed correctly, covers can sometimes be dislodged thus becoming ineffective. Glass Flake Epoxy (GFE) is a non-conductive thermoset plastic that can adhere to steel crossarms and not be dislodged. We hypothesized that GFE-coated crossarms might reduce faults (proxies for avian electrocutions), and we conducted laboratory and field trials to evaluate that hypothesis. In the laboratory, we found a 2000 micrometer (μm)-thick layer of GFE coating that created a dielectric strength of 12.30 ± 0.21 kV, which was sufficient to prevent the formation of a phase-to-ground fault on up to 20 kV distribution lines. This should allow birds to perch on metal crossarms without being electrocuted. In field trials, we substituted 24% of a 20 kV distribution pylon's crossarms with GFE-treated crossarms and found that doing so correlated with a 28% decrease in faults. Although we did not measure avian electrocutions directly, our findings suggest GFE coatings may offer a novel method of reducing avian electrocutions on power lines. [ABSTRACT FROM AUTHOR]

Owing to the atomically thin nature, two-dimensional (2D) oxide materials have been widely reported to exhibit exciting transport and dielectric properties, such as fine gate controllability and ultrahigh carrier mobility, that outperform their bulk counterpart. However, unlike the successful synthesis of bulk oxide single crystals, reliable methods for synthesizing large-area single crystal of 2D oxide, that would suppress the negative influence from defective grain boundaries, remain unavailable, especially for nonlayered oxide. Herein, we report that the lattice symmetry between the substrate and cerium dioxide (CeO2) would allow for the aligned nucleation and epitaxial growth of CeO2 on sapphire substrates, enabling the wafer-sized growth of CeO2 single crystal. The careful tuning of the growth temperature and oxygen flow rate contributed to the harvesting of CeO2 wafer with reduced thickness and enhanced growth rates. The removal of grain boundaries improved the dielectric performance in terms of high dielectric strength (Ebd ≈ 8.8 MV·cm−1), suppressed leakage current, along with high dielectric constants (εr ≈ 24). Our work demonstrates that with fine dielectric performance and ease of synthesizing wafer-sized single crystals, CeO2 can function as potential candidate as gate insulator for 2D-materials based nanoelectronics, and we believe the reported protocol of aligned nucleation can be extended to other 2D oxides. [ABSTRACT FROM AUTHOR]

Fluorinated gases, e.g., CF3I, C3F8, C4F8, C4F7N, and C5F10O, show potential to replace SF6 in power industry due to their high dielectric strength and low global warming potential. However, particle condensation from arc plasmas of these compounds may reduce dielectric performance. We perform a systematic investigation of particle condensation in two-temperature (2T) arc plasmas of various SF6 replacements mixed with CO2, N2, and O2, by the Gibbs free energy minimization and entropy maximization methods. The influences of buffer gases, non-equilibrium degree, and gas pressure on particle condensation are discussed in various cases. The results indicate that O2 is necessary to prevent graphite formation in carbon–fluorine gaseous arcs, and specific mixing ratios of CO2 and N2 are required to avoid graphite and iodine crystals in CF3I arc plasmas. The relationship between condensation temperature and non-equilibrium degree is complex, with peaks and valleys observed for graphite and iodine crystal condensation temperatures. Moreover, different calculation methods (Gibbs free energy minimization versus entropy maximization) show varying sensitivity of condensation temperatures to pressure changes. All the above findings highlight the importance of considering non-equilibrium effects and multiple condensed species in evaluating arc plasma compositions of SF6 replacements. [ABSTRACT FROM AUTHOR]

Modification of polymers with hybrid fillers has sought much attention in the past few years. The addition of hybrid fillers will lead to a synergistic effect in reinforcing and is advantageous in polymer nanocomposites. One such attempt is presented here that explores the effect of incorporation of hybrid derived from reduced graphene oxide (RGO) and multiwalled carbon nanotubes (MWCNT) on the dielectric and mechanical properties of plasticized polyvinyl chloride (PPVC). This system of hybrid composite incorporating RGO‐CNT and PPVC has not been prepared and reported yet. Melt mixing techniques were effectively used for the fabrication of PPVC nanocomposites containing the hybrid filler in different ratios. The prepared composites showed enhanced dielectric strength in the lower frequency region up to 450 and high AC conductivity. The mutual stacking and penetration of the 1D‐2D nanomaterials lead to effective dispersion and enhancement in the electronic conduction. Among the hybrids, the R1C5 (with the filler ration RGO 1 wt% and CNT 5%) was having the optimum properties. The tensile modulus showed a cumulative variation with the addition of CNT. Even though the tensile strength decreased slightly because of the immobilization of the PPVC chains by the hybrid effect, the modulus value showed a marked increase of over 90% from the virgin polymer. The PPVC composite with R1C5 hybrid filler exhibited an EMI shielding efficiency of ⁓23 dB and it was frequency independent. The results suggest the composite R1C5 should be used as a cost‐effective material for applications in the L‐band and S‐band regions. [ABSTRACT FROM AUTHOR]

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Lithium-ion batteries (LIBs) have the lead as the most used power source for electric vehicles and grid storage systems, and a battery thermal management system (BTMS) can ensure the efficient and safe operation of lithium-ion batteries. Epoxy resin board (ERB) offers a wide range of applications in LIBs due to its significant advantages such as high dielectric strength, electrical insulation, good mechanical strength, and stiffness. This study proposes an air-cooled battery module comprised of sixteen prismatic batteries incorporating an ERB layer between the batteries. To compare the performance of the ERB-based air-cooling system, two other air-cooling structures are also assessed in this study. Three-dimensional numerical models for the three cases are established in this paper, and the heat dissipation processes of the battery module under varying discharge rates (1C, 2C, and 5C) are simulated and analyzed to comprehensively evaluate the performance of the different cooling systems. Comparative simulations reveal that incorporating ERB into the battery assembly significantly reduces battery surface temperatures and promotes temperature uniformity across individual batteries and the entire pack at various discharge rates. Notably, under 5C discharge conditions, the ERB-based thermal management system achieves a maximum battery surface temperature increase of 16 °C and a maximum temperature difference of 8 °C between batteries. Additionally, this paper also analyzes the impact of battery arrangement on air-cooling system performance. Therefore, further optimization of the structural design or the integration of supplementary cooling media might be necessary for such demanding conditions. [ABSTRACT FROM AUTHOR]

For ferroelectric (FE) thin films, working in the harsh environment of a high electric field (E) or high temperature (T) remains a great challenge. As a post-treatment approach, dead-layer engineering exhibits a certain generality and could improve the dielectric strength (Eb) via depositing a specially designed artificial "dead-layer" on most of the as-prepared FE thin films. However, physical essence of the artificial dead-layer needs further analysis. Great challenges are the abundant and complicated conduction mechanisms in the FE-based thin films and the lack of adequate research on modulating these conduction mechanisms by this artificial dead-layer. As a vital part of the conduction mechanisms, electron injection can be easily triggered under E and thermal excitation that almost appeared in all FE-based thin films. Here, the ultrathin artificial dead-layer of Ca0.2Zr0.8O1.8 (CSZ) was used to restrain multiple electron injection in low-Eb LaNiO3/Ba0.58Sr0.42TiO3 (LNO/BST) FE thin films, including thermal emission and tunneling effect, under a high E and T, even under an opposite E. It was found that the suppressing effect on the multiple electron-injection mechanisms via the artificial dead-layer mainly comes from its wall-like energy-barrier structure, which is composed of two opposite and high interface energy barriers (BST/CSZ: 2.95 eV, CSZ/Au: 3.92 eV) and a wide depletion layer. The generality of protecting the ferroelectric thin films from electron injection via the artificial dead-layer was discussed. [ABSTRACT FROM AUTHOR]

A-site high entropy Ba4(La0.2Nd0.2Sm0.2Eu0.2Y0.2)2Ti4Nb6O30 tungsten bronze ceramics were designed and prepared by a standard solid state sintering process. First-order ferroelectric transition occurs around 240 °C on heating, while around 136 °C on cooling. Pinched and asymmetric P–E hysteresis loops were observed within and below the thermal hysteresis temperature range of the ferroelectric transition. Pinched P–E hysteresis loops were attributed to the coupling between the ferroelectric transition and the commensurate/incommensurate modulation transition. The reason for the asymmetry of the hysteresis loop was the presence of an internal bias electric field. Different measuring procedures were designed to clarify the evolution of hysteresis loop asymmetry. The existence of oxygen vacancy and Eu3+/Eu2+ was identified by x-ray photoemission spectroscopy. The electric field cycling with elevated temperatures caused defect dipoles incline to align along the direction of spontaneous polarization leading to the internal bias electric field. Due to the A-site high entropy effect, dielectric strength of Ba4(La0.2Nd0.2Sm0.2Eu0.2Y0.2)2Ti4Nb6O30 ceramics is up to 300 kV/cm, which is increased by more than 50% than that with the single element in the A1-site. [ABSTRACT FROM AUTHOR]

In modern electronics and power systems, good-performance dielectric capacitors have an essential function. Polymer-based dielectrics are widely used in the field of dielectric capacitors because of their large dielectric constant, flexibility, low density, and ease of processing. At present, ferroelectric polymers suffer from low breakdown field strength and high dielectric losses. How to improve the performance of dielectric materials in capacitors is still a promising research. This paper chooses the ferroelectric polymer poly(vinylidene fluoride) (PVDF) that worked as the matrix, and the linear polymers polyimide, cyanoethyl pullulan (CR-S), polyethersulfone, and cyanoethylated cellulose served as fillers. This all-organic dielectric composite produced as films working in electrostatic energy storage devices is prepared by using a casting method. Analyzing the test results, the composite film exhibited excellent electrical properties when the CR-S doping content was 5 wt. %. The organic composite dielectric based on CR-S/PVDF has a breakdown field strength of 450 MV/m, a discharge energy storage density (Ue) of 10.3 J/cm3, a high dielectric constant of 10.9, and a low dielectric loss of 0.004 at 1 kHz, which is a significant improvement compared with other dielectric composites. This all-organic dielectric composite strategy offers a new approach to achieve better-performance dielectric energy storage materials. [ABSTRACT FROM AUTHOR]

A straightforward scalable method for synthesizing β-poly (vinylidene fluoride) polymer foam from a sugar template has been used. A characteristic β-phase of the foam was confirmed by infrared and micro-Raman spectroscopy with significant enhancement observed after poling. The electrical polarization of the foam revealed a ferroelectric nature with dielectric strength higher than 30 kV/cm which is close to the commercial value. Poled samples had a dielectric constant of 5.5, higher than the value of the unpoled sample (3.05). These values appear stable over the low-frequency range from 1 kHz to 1 MHz. Significant reverse behavior was observed at higher frequencies from 300 GHz to 3 THz frequencies. It was found that the open-cell foam with a porosity of 88% has the lowest dielectric constant value (1.07 at 1.8 THz, reaching 1.04 at 2.9 THz) compared to the foam with 20% porosity (2.17 at 1 THz, reaching 1.83 at 3 THz). Furthermore, the Maxwell Garnett model, in conjunction with THz imaging, confirmed the impact of porosity on dielectric properties. These findings pave the way for the efficient fabrication of ferroelectric porous polymer structures that can be used in dielectric switching at the kHz–THz frequency range. [ABSTRACT FROM AUTHOR]

This study explores the impact of varying discharge gas compositions on the etching performance of silicon carbide (SiC) in a heptafluoroisopropyl methyl ether (HFE-347mmy)/O2/Ar plasma. SiC is increasingly favored for high-temperature and high-power applications due to its wide bandgap and high dielectric strength, but its chemical stability makes it challenging to etch. This research explores the use of HFE-347mmy as a low-global-warming-potential (GWP) alternative to the conventional high-GWP fluorinated gasses that are typically used in plasma etching. By examining the behavior of SiC etch rates and analyzing the formation of fluorocarbon films and Si-O bonds, this study provides insights into optimizing plasma conditions for effective SiC etching, while addressing environmental concerns associated with high-GWP gasses. [ABSTRACT FROM AUTHOR]

Alumina transparent ceramics, which possess great optical, mechanical, and dielectric properties, provide potential for applications in cross fields such as optics and electronics. Submicron grained alumina transparent ceramics were successfully fabricated via air pre-sintering combined with hot isostatic pressing (HIP) using ZrO 2 as a sintering additive. The influence of the ZrO 2 content on the densification process, microstructure evolution and properties of alumina ceramics were investigated. The alumina ceramic sample with 500 ppm ZrO 2 after HIP post-treatment at 1250°C for 3 h, has an average grain size of 0.89 μm, 54 % smaller than that of ceramics without additive, in-line transmittance of 53.5 % at 640 nm, bending strength of 592 ± 33 MPa, Vickers hardness of 20.3 ± 0.3 GPa, fracture toughness of 2.45 ± 0.04 MPa-m1/2, and dielectric loss of 5.7×10−4. [ABSTRACT FROM AUTHOR]

High dielectric constant and ultra-low dielectric loss are important for electronic device applications of dielectrics. In this work, the novel ceramic BaNd 2 Ti 4 O 12 , synthesized via solid-state reaction, exhibits remarkable dielectric stability, with excellent dielectric properties (ε ′ = 117 and tan δ = 6.27 × 10−4, at 1 kHz) and high dielectric strength (E b = 260 kV/cm). By exploring its polarization behavior and loss mechanisms at low frequencies for the first time, we found that the sustained high dielectric constant is attributed to the synergy of defect dipole polarization and interface polarization, while the observed exponential increase of dielectric loss is primarily caused by the conduction loss, with a minor contribution from the anelastic relaxation loss. In the low-temperature range of 50∼350 °C, the relaxation behavior is governed by the aggregation and subsequent thermal ionization of the oxygen vacancies, whereas at temperatures above 350 °C, it is predominated by the long-range motion of the doubly ionized oxygen vacancies. These findings provide valuable insights for the potential electronic device applications of BaNd 2 Ti 4 O 12. [ABSTRACT FROM AUTHOR]

Dielectric ceramics have attracted significant attention in power electronic systems, owing to their exceptional charging and discharging speeds, as well as their high power density. However, simultaneously achieving a high recoverable energy density (Wrec) and high efficiency (η) in high‐voltage dielectric ceramics remains a challenge for applications where a high breakdown electric field (Eb) is required. In this study, high‐quality (1 – x)NaNbO3–xSr0.7Bi0.2(Mg1/3Nb2/3)O3 [(1 – x)NN–xSBMN] ceramics were prepared based on an optimization strategy combining phase structure with microstructural regulation. A quasilinear P–E loop with negligible hysteresis was realized in the ceramic with x = 0.4, excellent Wrec of 5.61 J/cm3, and high η of 85.1% obtained at a largely improved Eb of 710 kV/cm. To the best of our knowledge, the Eb of 710 kV/cm is one of the highest values achieved in dielectric ceramics to date. The noticeable reduction in grain size (∼0.95 µm) and increased bandgap improve the Eb to an ultra‐high level, which is a crucial factor in high energy storage density. The coexistence of a few antiferroelectric phases and the dominant paraelectric phase is the structural origin of the comprehensive energy‐storage performance improvement. Therefore, our research develops a unique approach to unleash the potential in NaNbO3‐based ceramics, holding great promise for application in high‐voltage dielectric capacitors. [ABSTRACT FROM AUTHOR]

Temperature control of mould surfaces is of high relevance for part quality in moulding processes. Due to highly dynamic heating behaviour, heating elements applied by thermal spraying can be an alternative to existing tempering methods. To ensure the feasibility of these heating coatings on industry‐relevant moulds, the coating system needs to be applied onto more demanding non‐flat geometries. For this purpose, the spray angle of the plasma spraying process is varied during the application of the titanium oxide/chromium oxide heating coating and the insulating aluminium oxide coating. Subsequently, the results are related to application‐oriented cavity shapes. Spray angle deviations from the optimal perpendicular angle are leading to decreasing dielectric strength of the coating system and an increase of the electrical resistivity. Additionally, the application efficiency reduces with the spray angle variation. Knowledge of the spray angle's influence on coating properties can help to coat more demanding shapes, including free formed surfaces or corners. [ABSTRACT FROM AUTHOR]

We prepared sintered reaction-bonded silicon nitride (Si 3 N 4) by using various lanthanide oxides and magnesia for sintering additives and evaluated their effects on the microstructure and dielectric breakdown strength (DBS). Both the microstructure and DBS varied by the types of the sintering additives, and artificial intelligence (AI) based determination was conducted for the DBS to separate the effect of microstructural factors from that of sintering additives. The results indicated that the DBS values varied mainly by the former effect. The microstructures of Si 3 N 4 with Eu 2 O 3 and La 2 O 3 contained a large number of pores, leading to lowered DBS; on the contrary, those with Tm 2 O 3 and Y 2 O 3 possessed dense microstructures with large-elongated grains, showing higher DBS. On the other hand, the Si 3 N 4 with Yb 2 O 3 showed lower DBS than what AI-determined from the microstructures because the additive forms grain boundary phase with a low electrical resistance. [ABSTRACT FROM AUTHOR]

Power systems on the lunar surface require power lines of varying lengths and capacities to connect generation, storage, and load facilities. These lines must be designed to perform efficiently in the harsh lunar environment, considering factors such as weight, volume, safety, cost-effectiveness, and reliability. Traditional power transmission methods face challenges in this environment due to temperature fluctuations, micrometeoroid impacts, and ionizing radiation. Underground deployment, although generally safer, faces challenges due to low soil thermal conductivity. At a depth of 30 cm, the lunar temperature of −23.15 °C can be advantageous for managing waste heat. This study presents a novel approach, developed using COMSOL Multiphysics, for designing bipolar MVDC cables for lunar subsurface power transmission. Kapton® MT+ is chosen as the insulating material for its exceptional properties, including high thermal conductivity and superior dielectric strength. The cables are designed for voltages of ±10 kV and ±5 kV and capacities of 200 kW (low power), 1 MW (medium power), and 2 MW (high power). Our findings indicate that aluminum conductors offer superior performance compared to copper at medium and high power levels. Additionally, elevated voltage levels (±10 kV) enhance cable design and power transfer efficiency. These specially designed cables are well-suited for efficient operation in the challenging lunar environment. [ABSTRACT FROM AUTHOR]

Nanocomposites of poly(ε‐caprolactone) (PCL) reinforced by an organomodified beidellite (BDT) with 3% of cetyltrimethylammonium bromide (CTAB) (labeled PCL/3CTA‐BDT) were prepared by varying the content of filler (1, 2, 3, and 5 wt%). Their molecular dynamics were investigated by broadband dielectric spectroscopy at temperatures ranging from 0 to 40°C and a frequency window from 10−1 to 106 Hz. Three relaxation processes were detected for unfilled PCL: electrode polarization (EP), the Maxwell–Wagner–Sillars (MWS) polarization, and the α‐relaxation. The incorporation of the filler induced the emergence of a fourth process at high frequency of dipolar origin labeled as interfacial polarization (IP). Fitting the data with the Havriliak–Negami model as well as a study of the relaxation time variation with temperature demonstrated the noncooperative nature of the IP process. Activation energy and dielectric strength values demonstrated that the PCL/3CTA‐BDT with 3 wt% of filler showed a higher quality of dispersion and better interfacial features compared to those with other filler contents (2 and 5 wt%). This work highlights the challenges of dielectric green nanocomposites used for capacitors (storage energy) and cable/wire insulation. Highlights: The various samples were analyzed using broadband dielectric spectroscopy.Relaxation processes in pure matrix: EP, MWS, and α‐relaxation.Incorporation of the filler induced the emergence of interfacial polarization (IP).Noncooperative behavior of the IP process.3 wt% loading showed a higher quality of dispersion and interfacial features. [ABSTRACT FROM AUTHOR]

The degradation of electrical insulating materials has been a subject of interest for decades as they are commonly applied in many fields of electrical engineering. Suitably modeling such a process is important since the known and well-described degradation process reveals the effect of ambient conditions, and this allows us to possibly estimate a material's remaining useful life. However, not many studies are dealing with the effect of the hygrothermal degradation of impregnating mono-component epoxy resins in the context of electrical engineering. Therefore, this study deals with this issue and discusses both the dielectric response (based on the measurement of relative permittivity, dissipation factor, and dielectric strength) and the mechanical response (based on measurements of tensile strength and Shore D hardness) to a hygrothermal degradation experiment. In addition, the results of thermal analyses are presented for the evaluation of the pristine specimen manufacturing process and possible post-curing processes. Furthermore, this study presents several methodologies for modeling the degradation process, including a novel methodology in this area based on Bayesian experimental design. As an outcome, mechanical parameters are proven to be specific in terms of the actual condition of the material and the Bayesian enhanced degradation model seems to be superior to the conventional evaluation methods in this particular study. [ABSTRACT FROM AUTHOR]

To investigate the effects of point defects on the insulation performances of alumina ceramics, we fire a 95 wt% alumina ceramic in wet hydrogen, dry hydrogen, and supplementary air, to change the concentrations of aluminum vacancy (V Al ‴) and oxygen vacancy (V O • • ). The dielectric breakdown strength (DBS) and flashover voltage (FV) are tested, and the point defects are characterized by XPS and optical reflectance. Firing in wet hydrogen decreases the concentration of V O • • , improving DBS but deteriorating FV. Nevertheless, firing in dry hydrogen increases the concentration of V Al ‴ , improving FV but deteriorating DBS. Supplementary firing in air weakens the effects of firing in dry hydrogen on the point defects and insulation performances. The effects of firings on insulation performances are attributed to the concentrations of electrical carriers that are determined by the point defects, and this is confirmed by the results of electrical resistivity. [ABSTRACT FROM AUTHOR]

The expanding realm of high‐frequency electronics necessitates materials with exceptional attributes: notably, a low dielectric constant (Dk) to minimize signal propagation delays, high thermal conductivity for effective heat dissipation, higher breakdown strength, and robust mechanical properties to withstand demanding operational environments. While cycloolefin copolymers (COC) excel in electrical insulation, chemical resistance, and mechanical durability, their intrinsic slightly higher dielectric constant compared to other polymers, along with challenges such as poor dispersibility and low compatibility with nanoparticles, hinder their full potential in this domain. Considering these drawbacks, this study fabricated a series of COC/mica composites by integrating natural mica particles into the COC matrix via a CTAB‐assisted surface modification of mica to enhance dispersibility and mitigating particle aggregation through in‐situ mixing and hot‐press methods. The resultant composites demonstrate an outstanding ultra‐low Dk of 1.44, marking a significant decrease of over 36% compared to pristine COC with a Dk of 2.26, along with exceptionally low dielectric loss (δ) of 0.00013 at the frequency of 10 GHz, high dielectric breakdown strength ~49.40 kV/mm and enhanced thermal conductivity up to 0.88 W/(m K) at 40% mica loading. Additionally, the composites heightened mechanical performances like tensile strength 69 MPa at 6.5% elongation at break, impact strength up to ~17.9 kJ × m−2, and exceptional water resistance with absorption below 0.097%. These exceptional ultra‐low dielectric performance with above mentioned properties can meet the stringent requirements of modern high‐frequency electronics packaging for next generation electronics development. Highlights: Surface modification by CTAB enhanced homogeneous dispersibility of composites.Achieved ultra‐low dielectric constant and loss compared to pure COC.Thermal conductivity improved significantly with incorporation of mica.Unlocking high‐frequency applications potential with ultralow Dk performance. [ABSTRACT FROM AUTHOR]

The vast energy storage potential of polymer composite dielectrics in high pulse power sources stands in stark contrast to the unbalanced improvements in discharge energy density (Ud), charge–discharge efficiency (η), and dielectric strength (Eb) as reported currently. Herein, a multistage coupled interface engineering design is proposed: a novel gradient alternating dielectric buffer layer (G‐A‐DBL) is constructed, which consists of inorganic low‐k nanoclay aluminosilicate layer and high‐k ferroelectric layer assembled in a highly oriented alternation as a basic unit and gradient distribution in polymer matrix. This design achieves electric field confinement from the nanoscale to the macroscopic level and achieves an ultra‐balanced enhancement effect, resulting in a Ud of 28.5 J cm−3, an η of 80%, and an Eb of 676 kV mm−1. The universal charge retention ability of charge traps from aluminosilicate heterogeneous skeletons is demonstrated by combining density functional theory calculations and scanning probe measurements. The G‐A‐DBL design integrates traditional charge trapping, heterostructure formation, and gradient modulation, effectively suppressing the entire process of carrier excitation, transport, and before capture. This work advances the basic understanding of charge confinement within inorganic interface charge traps, demonstrating the most well‐balanced enhancement effect and potential for broad application across dielectric polymer nanocomposites. [ABSTRACT FROM AUTHOR]

Both the intrinsic and extrinsic contributions to the high energy storage properties of (K0.5Na0.5)NbO3 were investigated herein by employing Bi(Mg2/3Ta1/3)O3 as a second component to synthesize novel environment‐friendly energy storage ceramics. The role of the second component was confirmed to reduce the intrinsic activation of electrons, which effectively improves the band gap values and reduces the probability of intrinsic breakdown. Phase field simulation was employed to confirm that the smaller grain size of the modified ceramic microstructure enhances the extrinsic breakdown and dielectric breakdown strength. Moreover, ab initio molecular dynamics were used to investigate the critical role of the Mg ions in lowering the initial polarization and forming nanodomains, representing the intrinsic contribution to decreasing the initial polarization. An intrinsic structure with moderate polarization rapidly increases the polarization of ceramics under external electric fields, facilitating high energy storage density. The prepared ceramics achieve a recoverable energy density (Wrec) of 3.86 J/cm3 and energy efficiency (η) of 81.2% at 385 kV/cm. [ABSTRACT FROM AUTHOR]

Dielectric electrostatic capacitors are breakthroughs in energy storage applications such as pulsed power applications (PPAs) and miniaturized energy-autonomous systems (MEASs). Low power density, poor charge-discharge speed, and deprived breakdown strength of batteries and electrochemical capacitors limit their use in various implantable, wearable, and portable electronics. Recently, relaxor ferroelectric (RFE) and anti-ferroelectric (AFE) thin film capacitors have emerged as appropriate candidates for PPAs and MEASs. High energy storage density (50–120 J/cm3), large power density (109-1010 W/kg), ultrafast charge-discharge speed (μs range), superior dielectric breakdown strength (DBS) (∼MV/cm), and excellent thermal stability (150–275 °C) in RFE and AFE capacitors are appropriate for high power and miniaturized electronic device applications. In this review article, we portray a succinct discussion of the energy storage properties of RFE and AFE-based thin films. [ABSTRACT FROM AUTHOR]

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Composites derived from polyvinylidene fluoride (PVDF) play an important role in advanced dielectric energy storage due to their outstanding characteristics, including remarkable flexibility, low density, high dielectric permittivity, and superior dielectric breakdown strength. The strategically designed composition significantly enhances the energy storage performance, such as discharge energy density (Ue) and charge–discharge energy efficiency (η). Consequently, we employed the solution cast method to create flexible composite films, combining PVDF polymer with strontium tungstate (SrWO4) ceramic. X-ray diffraction analysis revealed the coexistence of α and electroactive β phases in PVDF. These phases have a substantial effect on the dielectric characteristics and energy storage density of composites. Flexible nanocomposites of PVDF and SrWO4 exhibit high dielectric constant and low tangent loss. Micrographs obtained using scanning electron microscopy (SEM) showed that the morphology of the composite varies according to the amount of filler present in the matrix. The impedance spectroscopy method yielded intriguing findings regarding the roles of both grain and grain boundaries in the overall resistance characteristics of the composites. The frequency-dependent behavior of alternating conductivity follows Jonscher's power law. The hysteresis loops indicate that the nanocomposite film maintains favorable ferroelectric properties. The present study suggests some promising applications for advanced dielectric capacitors and energy storage devices. [ABSTRACT FROM AUTHOR]

The research work proposed for the X-band microstrip line-based magnetic resonance imaging (MRI) coils has been accomplished with coplanar waveguide feeding and ha highlighted the design parameters to be employed in the internet of medical things (IoMT) features. The proposed research has focused on the wireless body area networks (WBAN) phenomenon in simulated human organs. It has been employed to study the electro-magnetic (EM) parameters of the simulated human organ and the functioning of wearable MRI coils on the human body. Therefore, these coils have been configured in triangle-shaped hierarchical structures, and each layer has been printed on both sides of the conductive strips. These proposed coils utilize a Bakelite substrate with a 1.6-mm thickness and an equivalent dielectric strength of 1.2. It has 69.9 × 85.2 × 1.6 mm3 dimensions and was fabricated using microwave integrated circuits (MIC). These coils have been generated at 8 GHz and this spectrum has been justified with the microwave X band (8–12 GHz) using the standard measured results. Hence, these coils have demonstrated 45.81-dB signal attenuation with a 1-dB standing wave ratio (SWR). Therefore, this research has extended to the different kinds of virtual simulation scenarios in diagnosis applications. Additionally, the research delves into the electromagnetic characteristics, encompassing electric and magnetic fields, the specific absorption ratio (SAR), and temperature. These characteristics are thoroughly analyzed using MRI phantom models within virtual environments. As a result of this comprehensive analysis, the suitability and efficacy of these MRI coils have met rigorous standards. These coils are highly demanded by complicated systems functioning in these bands for IoMT and MRI diagnosis applications. [ABSTRACT FROM AUTHOR]

This study presents the dielectric properties of a barium titanate–gadolinium ferrite composite material, obtained through a solid-state reaction method. The aim of this research was to create a composite material with enhanced dielectric properties compared to each individual component, and to investigate the electrical properties of the composites, using impedance spectroscopy. The structural and morphologic properties were analyzed using X-ray diffraction and scanning electron microscopy, respectively. Impedance spectroscopy measurements were performed over a wide frequency range (100–0.1 GHz) and temperature (45–170 °C) to evaluate the electrical behavior of the material. The dielectric relaxations were analyzed using the Havriliak–Negami function, and the key electrical parameters such as relaxation frequency, dielectric strength, and electrical conductivity were extracted. Several relaxation processes were identified, which depend on the mixture of the initial titanate and ferrite materials, and a correlation between structural, morphologic, and electrical properties was exposed. The sample with the highest dielectric constant was the 25 wt% gadolinium ferrite composite, with ε′ close to 240 and loss tangent values below 0.1, affording it the more appropriate composition for energy storage devices such as lead-free dielectric capacitors. [ABSTRACT FROM AUTHOR]

For wide-body all-electric aircraft (AEA), a high-power-delivery, low-system-mass electric power system (EPS) necessitates advanced cable technologies. Increasing voltage levels enhances power density yet poses challenges in aircraft cable design, including managing arc-related risks, partial discharges (PDs), and thermal management. Developing multilayer multifunctional electrical insulation (MMEI) systems for aircraft applications is a feasible option to tackle these challenges and reduce the size and mass of cable systems. This approach involves selecting layers of different materials to address specific challenges. Our prior research concentrated on the modeling and simulation-based design of MMEI systems for MVDC power cables. Experimental tests are essential for determining the behavior of PDs under varying pressure conditions. Also, the dielectric strength and time to failure of the designs need to be assessed. In this work, the fabrication process of a down-selected MMEI flat configuration is discussed and analyzed. This paper analyzes the fabrication process of power cables employing MMEI configurations and evaluates the PD characteristics of down-selected ARC-SC-T-MMEI cable samples. This study presents a detailed analysis of the characteristics of PD under atmospheric and low-pressure conditions, which will provide essential insights into the design of MVDC cables for future AEA applications. [ABSTRACT FROM AUTHOR]

The environmental challenges associated with high-power, high-voltage electrified aircraft require a targeted approach with regard to the development of next-generation aerospace electrical insulation. This study reports findings on polyphenylsulfone (PPSU) as a matrix material based on its unique thermal, mechanical, and dielectric properties, filled with hexagonal boron nitride (h-BN) with micron- and nanoscale particulates. The inorganic ceramic filler was selected for its thermally conductive and electrically insulating performance in extreme environments. The main goal was to investigate the dielectric strength and electrical resistance (endurance) to partial discharges (PDs). Since PDs are a leading accelerated degradation phenomenon causing premature failure in organic electrical insulation, the capability of an insulating material to endure PD-induced degradation for the whole (or part of) its design life is of paramount importance. It was observed that incorporation of h-BN micro fillers can significantly improve the PD resistance, even in comparison with insulating materials typically used for electrified transportation, such as corona-resistant Kapton. It was also observed that a suitable combination of micro and nano fillers can also be used as a viable solution to increase the electrical performance and reliability of the avionics insulation components. [ABSTRACT FROM AUTHOR]

Ceramic/polymer dielectrics with excellent thermal stability and high dielectric performance exhibit great potential in advanced capacitor applications. It is still a major challenge for ceramic/polymer dielectrics to obtain high dielectric constant at low content while maintaining excellent flexibility. To alleviate this issue, here, a flexible polymer dielectric composite consisting of poly(arylene ether nitrile) (PEN) matrix and barium titanate filler coated by Carbon and polypyrone (h-BT@C@PPy) was put forward in this work. The as-prepared composite films displayed high dielectric constant, comparable low loss and favorable interfacial binding due to the hydrogen-bonding interaction between –NH of h-BT@C@PPy and –CN of PEN, effectively promoting the interfacial polarization and remedying the internal interface defects between h-BT and PEN. Consequently, an addition of 8 wt% h-BT@C@PPy into PEN matrix raised the dielectric constant from 3.82 to 13.3 at 1 kHz, while maintaining relatively low dielectric loss (0.05@1 kHz). However, the breakdown strength showed a decreasing trend with the lowest value of 60.37 kV mm−1. Meanwhile, the better flexibility, outstanding thermal stability (the 5% weight loss above 500 °C) as well as excellent permittivity-temperature stability was also delivered by the PEN-based composite films. This strategy furnishes a perspective to design ceramic/polymer dielectrics with high-k achieved at low filler content for the applications of organic film capacitors. [ABSTRACT FROM AUTHOR]