Search

Glass-ceramic is widely used in aerospace, bionics, optics and other fields with low expansion and high strength and low dielectric loss, but its hardness and brittleness as well as its high strength have been classified as a kind of difficult-to-process materials. In this paper, free-form machining of glass-ceramic is performed by combining a pulsed laser with fast tool servo (FTS) technology to utilize laser-induced irradiation effects. During pulsed laser synchronously enhanced servo-turning (s-LAST), the material removal process as well as the selection range of operating temperatures were first determined by means of finite elements. The cutting forces on hard and brittle glass-ceramic materials during laser-assisted manufacturing (LAM) were predicted by developing an analytical force model that takes into account the thermal manufacturing damage caused by laser irradiation, using the discretisation method as well as the shear and ploughing effects associated with laser heating. The s-LAST experiments were performed on a selected ultra-low expansion glass-ceramic (Zerodur), and both the modelling and experimental results were validated, with laser irradiation leading to a 12 % reduction in cutting force, and an average principal cutting force of 3.124 N was recorded. [ABSTRACT FROM AUTHOR]

To comprehend the mechanism of dielectric breakdown (DB) is fundamental for the work on improving the dielectric breakdown strength (DBS). Changing DB test in order to find the difference in DBS and DB channels is always one of the most important methods of studying mechanism of DB. In this paper, 6 different electrode set-ups were applied to the DB test of alumina ceramics with various sample thicknesses, and the effects of electrode and sample thickness were analyzed from the statistical characteristics of DBS data. Some phenomena were found: DBS first increased and then decreased with the increase of electrode size, and this could be attributed to the effect of electric field concentration and the area effect, and Weibull scaling law could be applied to analyze the area effect; the thickness-dependence of DBS was found in every electrode set-up, and none of the proposed mechanisms of DB could fully explain it; multi-layer series improved the high voltage resistance of alumina ceramic sheets, and the improvement factor was smaller than the predicted value on the base that the voltage-distribution ratio is equal in each layer. [ABSTRACT FROM AUTHOR]

Herein, microwave dielectric ceramics of the Ba 4 Sm 9.33 Ti 18 O 54 ceramics are substituted at A sites by partially replacing Sm at A1 sites with Ce, and the effects of ionic substitution at A sites on ceramic crystal structure and microwave dielectric properties are investigated. The Ba 4 (Sm 1-x Ce x) 9.33 Ti 18 O 54 (BSCT) ceramics prepared through the solid phase method has a typical tungsten–bronze structure, and its lattice spacing increases gradually with the increase in Ce content x. This increase is reflected in the increase in the cell volume and growth of ceramic grains. However, the excess Ce after Ce content exceeds 0.25 leads to the growth of ceramic grains and increase in porosity between grains, which in turn increases the dielectric loss of the ceramic. Under optimal sintering conditions, the ceramic crystal has a maximum atomic packing density of x = 0.25, which corresponds to its most stable structural properties, and the highest Q × f value of 9013 GHz. Raman spectroscopy results indicate that in titanium oxygen octahedrons, an increase in Ce substitution can effectively weaken the bending and tensile vibration intensities of titanium oxygen bonds, further enhancing structural strength. [ABSTRACT FROM AUTHOR]

Antiferroelectric (AFE) materials are potentially useful for energy storage applications. Lead hafnate (PbHfO 3) is one of the prototypical AFE materials. However, its critical field (E cr) which is needed to induce the AFE to ferroelectric phase transition is close to the dielectric breakdown strength. To reduce E cr , we prepare the solid solutions of (1- x)PbHfO 3 – x BiAlO 3 (x = 0.00–0.04) via solid state synthesis. The crystal structures, dielectric behaviour, ferroelectric properties, and energy storage properties are investigated. A temperature-composition phase diagram is established. At room temperature, the crystal symmetry of all compositions is orthorhombic with the Pbam space group. Upon heating, the transition to the AFE orthorhombic Imma phase is observed at the temperature T C1 , which slightly decreases with increasing x , followed by the transition to the cubic phase at the temperature T C2 , which does not depend on x. Distinct dielectric anomalies are observed at T C1 and T C2. It is found that BiAlO 3 substitution reduces E cr and the polarization–electric field relations display characteristic double hysteresis loops. For x = 0.04, at a comparatively small applied field of 130 kV/cm, the values of recoverable energy density (W rec) and efficiency of 0.24 J/cm3 and 84 %, respectively, are obtained. At 190 °C, a W rec = 0.75 J/cm3 and a very high efficiency of 92 % are obtained at the field of 50 kV/cm. Thus, the prepared material can potentially be used in high-temperature pulsed power capacitors for energy storage applications within the temperature range from room temperature up to 190 °C. [ABSTRACT FROM AUTHOR]

Ferroelectric ceramic capacitors have potential advantages in energy storage performance, such as high energy storage density and fast discharge speed, making them widely applicable in different energy storage devices. During heat treatment, ferroelectric ceramics undergo an evolution of grain growth leading to changes in dielectric properties. Optimizing the energy storage properties of ferroelectric ceramics during heat treatment is a crucial issue. In this work, a phase field modeling for dielectric breakdown coupled with a grain growth model is developed to give a fundamental understanding of the effect of grain growth on dielectric breakdown. In addition, this work proposes a breakdown detection method to shorten the computational time of the model. The results indicate the existence of a local maximum of the breakdown field strength during grain growth, leading to a local maximum of the energy storage density. It is found that the dielectric breakdown strength and the pattern of the final breakdown path are significantly influenced by the grain size and distribution. The model is also applicable to various dielectrics and provides guidance for the design of high-energy storage dielectrics. [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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

In this study, a ternary solid solution was designed by incorporating varying concentrations of the B-site composite perovskite Ba(Mg 1/3 Ta 2/3)O 3 (BMT) into 0.91Na 0.5 Bi 0.5 TiO 3 -0.09K 0.7 La 0.1 NbO 3 (NBT-KLN-based) ferroelectric ceramics to optimize their energy storage performance. The introduction of BMT disrupted the long-range ordered state of the A/B site in the original perovskite structure, resulting in increased structural disorder and enhanced relaxor characteristics. The viscous polymer processing (VPP) method was employed to attain a significantly denser structure. The 0.10BMT-vpp ceramic has ultimately achieved optimal energy storage performance, along with exceptional temperature and frequency stability. It boasts a high dielectric breakdown strength (BDS) of 440 kV/cm, an ultra-high effective energy storage density (W rec) of 6.7 J/cm3, and an energy storage efficiency (η) of 82%. Moreover, the 0.10BMT-vpp ceramic exhibits robust pulse performance, characterized by an ultra-fast discharge time (t 0.9) of only 77 ns. Furthermore, within the temperature range of −66 °C–354 °C, the temperature coefficient of capacitance (TCC) of the 0.25BMT ceramics undergoes a variation of no more than ±15%, in compliance with X9R specifications (−55 °C–200 °C). The introduction of BMT endows NBT-KLN-based ceramics with remarkable temperature stability and comprehensive energy storage performance, making it a ceramic material with practical potential for industrial applications. [ABSTRACT FROM AUTHOR]

Silicon nitride (Si 3 N 4) ceramics were prepared using various amounts of magnesia (MgO) and a fixed amount of yttria as sintering additives, and their effects on the microstructures and four essential properties were evaluated: bending strength, fracture toughness, thermal conductivity, and dielectric breakdown strength (DBS). The microstructure varied with the MgO content; a smaller amount promoted grain growth, while an excess amount formed pores. The properties varied along with these structural changes. It was revealed that the four properties coexist at a high level in the range of 4–7 mol% of MgO. In addition, the large amount of MgO enhanced the electric conductivity of grain boundary and decreased the DBS. It is speculated that tips of multigrain junctions composed of a sufficiently large amount of glass modifier might work as the severe defects for the dielectric breakdown. [ABSTRACT FROM AUTHOR]

Ceramic dielectrics have been extensively studied due to their high-power density and fast charge/discharge rate. However, simultaneously increasing their dielectric permittivity and breakdown strength remains a formidable challenge. Here, the novel sandwich structure ceramic dielectrics are designed, in which monodisperse gold nanoparticles are sandwiched by two ceramic layers. The effects of gold nanoparticles with different sputtering times on the dielectric breakdown performance of the composite ceramics are investigated. The results show that the dielectric permittivity and breakdown strength of barium titanate composite ceramics with 3 min gold nanoparticle interlayer (BT-3Au-BT) reach 6017.5 (10 kHz) and 111.4 kV/cm, respectively, which are 9 % and 18 % higher than that of barium titanate ceramics without gold nanoparticle interlayer (BT-0Au-BT). The improved dielectric permittivity is originated from the formation of numerous micro-capacitors. The enhanced breakdown strength is attributed to the Coulomb blockade effect of gold nanoparticles. This work provides a novel, easy-to-operate and scalable approach for synergistically improving the dielectric permittivity and breakdown strength of dielectric materials, which opens up a novel way for the design of high-performance dielectric materials and would also be enlightening for the exploration of other functional nanocomposites. [ABSTRACT FROM AUTHOR]

Na 0.5 Bi 0.5 TiO 3 (NBT)-based ceramics are promising lead-free candidates for energy-storage applications owing to their individual crystal structure and phase transition information. However, the high coercive field (E C) and large remnant polarization (P r) are detrimental for practical applications. In this work, the composition-dependent phase structure, micromorphology, dielectric and energy storage properties of (1-x)(0.94Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3)-xBi(Mg 2/3 Nb 1/3)O 3 (NBBT-100xBMN, x = 0.18, 0.20, 0.22 and 0.25) ternary ceramics were hereby investigated. The addition of BMN facilitates the phase transformation from rhombohedral (R3c) to tetragonal (P4bm), which is beneficial for the enhancement of relaxation behavior, and meanwhile impels the grain growth. Combined with the influence of grain size on breakdown field strength, an optimal recoverable energy storage density (W rec) of 1.88 J/cm3 with a high energy storage efficiency (η) of 82.15% was achieved in the NBBT-20BMN ceramic composition under the dielectric breakdown strength (DBS) of 150 kV/cm, accompanied by the excellent temperature stability from room temperature to 200 °C. All these manifest that the NBBT-20BMN ceramics have an attractive application prospect in the energy storage field. [ABSTRACT FROM AUTHOR]

Thin-amorphous Al 2 O 3 (AO) insulating layers inserted into the SrRuO 3 -top-electrode/Pb 0.9 La 0.1 Zr 0.52 Ti 0.48 O 3 (PL)/SrRuO 3 -bottom-electrode/Si structures have been developed for enhancing the energy-storage performance of dielectric thin-film capacitors. It is found that the relaxor-paraelectric transition is observed by the insertion of the AO layer, and the paraelectric behavior of the films becomes stronger with the movement of the AO layer into the PL layer. Herein, a marked enhancement in breakdown strength from 2.5 to 5.8 MV/cm has been achieved in the PL single-film and PL/AO multilayer-film, which is the result of the simultaneous contributions of amorphous AO and pyrochlore-phase PL layers. As a result, an ultrahigh-recoverable energy-storage density of 90.7 J/cm3 and excellent energy-efficiency of 75.2% are simultaneously achieved in the PL/AO multilayer-film via the structure modulation. The findings provide an effective way to enhance the energy-storage density and breakdown strength of dielectric films via a combination of relaxor PL and amorphous AO layers. • Introduction of an amorphous Al 2 O 3 layer into the relaxor PLZT film is beneficial to enhanced breakdown strength. • PLZT film grown on Al 2 O 3 layer has a dominant pyrochlore phase. • Position of inserted Al 2 O 3 layer has enormous impact on energy-storage density. • Maximum U r of 90.7 J/cm3 and high η of 75.2% are achieved in PLZT/Al 2 O 3 /PLZT multilayer. [ABSTRACT FROM AUTHOR]

Glass-ceramics have demonstrated excellent dielectric properties in low-temperature co-fired ceramic (LTCC) technology used in 5G/6G wireless devices. This work studies the mechanical strengths and dielectric properties from microwave to millimeter-wave frequencies in the CaO–SiO 2 glass-ceramics modified via the P 2 O 5 as a nucleating agent. The β-wollastonite phase was identified as the primary structure with the preferred (20 2 ‾) orientation and parallel plate-like structure in the matrix as P 2 O 5 content increases up to 3.5∼5.5 wt%. The P 2 O 5 nucleating agent increases degree of long-range crystallization. Elevated mechanical flexural strength of approximately 170 MPa, hardness of ∼720 MPa, and outstanding high-frequency dielectric properties were obtained in the 3.5–5.5 wt% P 2 O 5 -added CaO–SiO 2 glass-ceramics, due to the enhanced interatomic Si–O bonding in the network. The improved mechanical and dielectric characteristics of the P 2 O 5 –added CaO–SiO 2 glass-ceramics make the crystallized wollastonite materials for the 5G/6G devices possible. [ABSTRACT FROM AUTHOR]

In this work, (Bi 0.65-0.65 x Ba 0.35-0.35 x Nd x)(Fe 0.65-0.65 x Ti 0.35-0.35 x Nb x)O 3+ x (abbreviated as: BFBT- x NN, x = 0, 0.04, 0.08 and 0.12) ceramics were fabricated through a solid-state reaction method, aiming to obtain high-performance capacitor materials. BFBT ceramics have attracted increasing attention as potential energy storage materials because of their excellent dielectric and ferroelectric properties. However, two handicaps limit the large improvement of their energy storage performance (ESP). One is the large hysteresis of their polarization (P)-electric field (E) loops; the other is the low dielectric breakdown strength (E b), which has a close correlation with the inevitable defects present in BF-based ceramics. Herein, we designed a co-doping strategy to overcome the two handicaps in order to achieve high ESP in BFBT ceramics. In this strategy, the trivalent rare earth Nd3+ ions and high valence Nb5+ ions are simultaneously introduced at the perovskite A- and B-sites of BFBT ceramics, which is called NN co-doping. The NN co-doping enhances the relaxor properties of BFBT ceramics due to the enhanced composition and charge fluctuations and promotes the formation of the Bi-rich phases, which contribute to the appearance of a slim P - E loop. Meanwhile, the E b of BFBT ceramics is enhanced, which is ascribed to the significantly decreased oxygen vacancy concentration, the reduced grain size and the Bi-rich phases. Benefitting from these factors, a high recoverable energy storage density (W rec) of 3.64 J/cm3 and energy storage efficiency (η) of 88% are simultaneously obtained under an enhanced E b of 330 kV/cm in BFBT-0.08NN ceramics. Moreover, the ESP of BFBT-0.08NN ceramics shows good thermal stability (30–150 °C) and charge-discharge properties. These results indicate that BFBT-0.08NN ceramics could be a promising capacitor material. [ABSTRACT FROM AUTHOR]

In this work, the neglected role of the dielectric breakdown strength (BDS) in piezoelectricity of bismuth layer-structured ferroelectrics (BLSFs) is revealed, enhanced initial polarization and BDS work together to improve the piezoelectricity of CaBi 4 Ti 4 O 15 (CBT) ceramics via Li/Bi co-substitution. The experimental work, first-principles calculations and finite element simulation are carried out to investigate the effect of Li/Bi co-substitution in depth. The stronger spontaneous polarization (P s) from the lattice distortion and the more favorable domain switching from the improved grain growth both contribute to an enhanced initial polarization. Besides, the changed grain-scale microstructure improves the hardness and inhibits the local discharge, the higher resistivity related to strong defect dipoles suppresses the heat generation during the poling process, all resulting in an increase of BDS by about 100%, and allowing more domains to align. This work demonstrates an effective strategy to develop BLSFs with enhanced piezoelectricity for high temperature piezoelectric applications. [ABSTRACT FROM AUTHOR]

Epoxy-based composites with high insulation and thermal conductivity are desirable materials for electronic and electrical applications. However, resolving the tradeoff between insulation and thermal conductivity remains challenging. Based on the functional requirement, we designed and fabricated a cactus-like double-oriented epoxy composite by combining magnetic orientation and ice-templated methods. Semiconducting SiC endowed the composite with field-grading characteristics, thus relieving local electric field stress along the horizontal direction, while BN with high thermal conductivity promoted heat dissipation along the vertical direction. The composite exhibited its highest performance with 15 vol% filler, improving the breakdown voltage and thermal conductivity by 43.7% and 1312% compared with pure epoxy, respectively, outperforming recently developed packaging materials. It is believed that this work offers an efficient strategy for the fabrication of the filler structure and provides insights on the simultaneous enhancement in insulation and thermal conductivity of polymer composites. [ABSTRACT FROM AUTHOR]

(1–x) Ba 0.55 Sr 0.45 TiO 3 –xBi(Mg 0.5 Ti 0.5)O 3 (x = 0, 0.08, 0.1, 0.12, 0.15, 0.2) ceramics were fabricated via a solid-state reaction route. The ultrahigh recoverable energy density (W rec = 4.05 J cm−3), efficiency (η = 78%), maximum polarization (P max = 51.40 μC cm−2), and high dielectric breakdown strength (BDS = 230 kV cm−1) were achieved for the 0.9BST−0.1BMT ceramic. The fast discharge rate (t 0.9 ∼0.14 μs), current density (C D ∼637.02 A cm−2), high power density (P D ∼38.70 MW cm−3), good temperature stability (20−180 °C), frequency stability (10−500 Hz), and fatigue endurance for cycling (105) of 0.9BST−0.1BMT ceramic make it suitable for the development of energy-storage devices. The relaxor behavior with a high W rec (3.06 J cm−3) and η (93%) at BDS (220 kV cm−1) was also achieved for the 0.8BST−0.2BMT ceramic. This study systematically investigates the correlation among the structural, dielectric, impedance, and energy storage properties of BMT-doped BST ceramics. • (1–x)Ba 0.55 Sr 0.45 TiO 3 –xBi(Mg0.5Ti0.5)O 3 (x = 0–0.2) ceramics were fabricated via a solid-state reaction route. • Impedance spectroscopy was used to investigate the electrical properties of the (1– x)BST–xBMT ceramics. • The ultrahigh W r ec (4.05 J cm−3) and η (78%) at BDS (230 kV cm−1) were achieved for the 0.9BST−0.1BMT ceramic. • The composition (x = 0.1) possesses promising pulsed charging–discharging response, temperature stability , frequency stability, and fatigue endurance. • These ceramics have the potential for their possible applications in advanced pulsed power capacitors. [ABSTRACT FROM AUTHOR]

Lead-free ceramics with prominent energy storage properties are identified as the most potential materials accessed in the dielectric capacitors. Nevertheless, high recoverable energy storage density (W rec), large energy storage efficiency (η) and preferable temperature stability can hardly be met simultaneously. The Bi(Zn 2/3 Ta 1/3)O 3 and NaNbO 3 components are doped in KNN ceramics to substantiate the reliability of this tactic. A high recoverable energy density (W rec) of ∼ 4.55 J/cm3 and a large energy storage efficiency (η) of ∼ 87.8% are acquired under the dielectric breakdown strength (DBS) of ∼ 375 kV/cm, along with a splendid thermal stability (W rec variation: ∼ 2.3%, η variation: ∼ 4.9%) within the temperature range of 20 ℃− 120 ℃. This article demonstrates that the KNN-based ceramics integrate high energy storage properties and outstanding temperature stability at the same time, which broadens the application fields of pulse power systems. [ABSTRACT FROM AUTHOR]

To investigate the dielectric strength and mechanical features of modified nitrile butadiene rubber (NBR), titanium dioxide (TiO 2) and magnesium oxide (MgO) nanoparticles have been used. Specimens have been experimentally prepared with loading various concentrations (0.5, 1, 1.5 and 3 parts per hundred part of rubber "Phr") to NBR base material. The dielectric strength has been evaluated by applying AC high voltage on the prepared samples up to reaching the breakdown state. On the other hand tensile strength, elongation at break and modulus at 100% elongation have been experimented to exploration the mechanical features of the NBR enhanced by nanoparticles. Although all the recorded results of modified NBR samples showed improvement more than the base material at dielectric, tensile strength and modulus at 100% elongation tests. The elongation at break result showed a negative impact; it was caused by forming a new links between NBR and nanoparticles. The dielectric constants of applied nanoparticles are greater than NBR base materials, which can physically explain the improvement in all recorded breakdown results. But the enhancement in the measured mechanical features can be attributed to chemical bonds which were reconstructed and the gaps of NBR base material that had been filled. [ABSTRACT FROM AUTHOR]

This study demonstrates the high energy-storage performance using 0.1 wt% MnO 2 –added 0.7(Bi 1−x Sm x FeO 3)− 0.3(BaTiO 3) (x = 0–0.3) ceramics through tailoring microstructures and polar order. Sequential structure transitions were identified from a co-occurrence of nonpolar pseudo-cubic Pm- 3 m and ferroelectric rhombohedral R 3 c symmetries to antipolar orthorhombic Pbam and nonpolar orthorhombic Pnma symmetries as Sm substitution increases. Recoverable energy densities (W rec) of 4.5 J/cm3 and 4.1 J/cm3 with efficiencies (η) of 62.1% and 78.1% were achieved respectively for x = 0.15 and 0.2 at a field of 220 kV/cm. The improved energy storage is associated with microstructure modification and complex grain matrix, consisting of grain boundaries, nanocluster/nanomosaic structures, core-shell structures, and polar nanoregions. The nanocluster/nanomosaic structures may act as barriers to suppress polar order and enhance dielectric breakdown strength. This work provides an efficient route to utilize binary BiFeO 3 -BaTiO 3 ceramics for electrical energy storage. [ABSTRACT FROM AUTHOR]

High-performance lead-free dielectric energy storage films have received a lot of attention in the modern electronics industry. In this work, sandwich structured SiO 2 /Ba 0.6 Sr 0.4 Ce 0.05 Ti 0.95 O 3 (BST-Ce)/ZrO 2 and Al 2 O 3 /BST-Ce/ZrO 2 composite films were prepared on ITO/glass substrate by a combination of electron beam evaporation and post-annealing. With the introduction of linear dielectric SiO 2 , Al 2 O 3 , and ZrO 2 layers, a high recoverable energy storage density (W r e c ) of 55.4 J/cm3 and an efficiency (η) of 78% was obtained in SiO 2 /BST-Ce/ZrO 2 film; an optimal W r e c of 71.5 J/cm3 and η of 86.1% was obtained in Al 2 O 3 /BST-Ce/ZrO 2 film. Moreover, the sandwich structured multilayers also exhibit an excellent thermal stability, high frequency stability and good fatigue durability. Due to the existence of the electron injection barrier in the interfaces, the schottky emission of the BST film under high electric field and high temperature is effectively suppressed, thereby greatly improving the dielectric breakdown strength. The Al 2 O 3 /BST-Ce/ZrO 2 composite film is promising for the energy storage applications working in the harsh environment of high temperature and high electric field. Our results also show that the sandwich-structured composite film composed of relaxor ferroelectric and linear dielectric layers is an effective method to improve energy storage performance. [ABSTRACT FROM AUTHOR]

The actual pulse capacitor application of BiFeO 3 -based relaxor ferroelectric ceramics has been greatly hindered by low dielectric breakdown strength and poor thermal stability. In this work, these issues are solved by manufacturing nanodomain-engineered and grain-engineered BiFeO 3 -BaTiO 3 -CaTiO 3 relaxor ferroelectric ceramics. The introduction of CaTiO 3 induces nanoscale domains in the ferroelectric BiFeO 3 -BaTiO 3 matrix, bringing about temperature-insensitive dielectric response and almost hysteresis-free polarization field response. Furthermore, largely enhanced dielectric breakdown strengths are also achieved, which is mainly attributed to the refinement of the grain size and the depression of the oxygen vacancy concentration. Consequently, remarkable energy-storage performances with high recoverable energy density (W rec ∼ 5.03 J/cm3), high efficiency (η ∼ 89.7%), and outstanding thermal stability (W rec variation < 4% from 30 to 150 ℃) are obtained. Moreover, ultrafast release time (t 0.9 ∼ 65 ns) and high power density (∼75.14 MW/cm3) are also achieved, proving the BiFeO 3 -BaTiO 3 -CaTiO 3 ceramics' enormous potential for underlying advanced pulse capacitor applications. [ABSTRACT FROM AUTHOR]

Sugarcane bagasse ash (SCBA) industrial waste was used to partially substitute feldspar in the production of porcelain electrical insulators from a mixture of locally available Bombawuha clay (BC), Chancho sand (CS), and mixture of Wolkite (WF) and Arerti feldspar (AF) (50:50%). The raw materials were characterized for their chemical composition, mineralogy, thermal behavior, and plasticity. The porcelain electrical insulator formulations containing various proportions of SCBA (0 wt%, 10 wt%, 15 wt%, and 20 wt%) were fired at different firing temperatures of 1200 °C, 1250 °C, and 1300 °C for 2.5 h. The fired bodies were evaluated for water absorption, apparent porosity, bulk density, flexural strength, dielectric strength, and microstructure. The results showed that SCBA had 65.06% silica (SiO 2) and had higher alkaline and iron oxide (Fe 2 O 3) contents than the natural feldspars. Bombawuha clay contained kaolinite as a major mineral with a middle range plasticity index (PI = 11.2%) and the met the required purity necessary for mullite phase formation. The feldspars had a low alkali content of sodium oxide plus potassium oxide (Na 2 O + K 2 O) of < 6 wt %. The prepared porcelain insulator containing 10% SCBA, 50% BC, 30% mixed feldspars, and 10% CS, and fired at 1250 °C for 2.5 h exhibited a water absorption of 0.35%, flexural strength of 42.50 MPa, and a dielectric strength of 6.59 kV/mm, which satisfies the obligatory properties for quality porcelain insulators. Further, the partial replacement of feldspar by SCBA up to 10 w% lowered the firing temperature by 50 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • The successful development of bisphenol-A EP with superior electric breakdown strength (366.39 kV/mm) and competitive T g (140.91 °C). • Applicating DFT and MD simulations to provide guidance for the development of high-performance epoxy resin. • Elucidates the relationship between macroscopic performance and microscopic structures in epoxy resins. In this research, we optimized both the molecular and crosslinked structures of epoxy resin to achieve exceptional breakdown strength and a competitive glass transition temperature (T g). Through simulations, we found that the epoxy molecule with a polymerization degree of 0 (Ep 0) exhibited a wider bandgap (E g) and developed a dense crosslinked structure with higher density after crosslinking. This countered the negative impact of a reduced benzene structure, enhancing molecular rigidity and improving T g. We isolated Ep 0 components and prepared samples demonstrating a significant 22.18 % increase in breakdown strength (366.39 kV/mm vs. 299.87 kV/mm for commercial EP) and a T g of 140.91 °C. The superior insulation properties of our product stem from its higher E g molecular structure, while the competitive T g is attributed to its compact crosslinked structure and increased density. [ABSTRACT FROM AUTHOR]

Polymer-based dielectric films are increasingly demanded for capacitive energy storage. However, the negative coupling between dielectric constant (ɛ r) and breakdown strength (E b) presents a significant challenge to further enhancements, especially at high temperatures. Here, we propose dielectric composite films employing poly(m -phenylene isophthalamide) (PMIA) as the matrix, with nanodiamond (ND) particles modified by polydopamine (PDA) serving as reinforcing fillers. At 150 °C, the 1.0 wt% film demonstrates an ultrahigh discharge energy density (U e) of 5.15 J/cm3 at a charge-discharge efficiency (η) exceeding 90 %. Even the temperature increases to 200 °C, the film maintains a desirable U e of 2.36 J/cm3 with η > 90 %, achieving a record energy storage performance that outperforms numerous previous works. In addition to the inherent hydrogen bonds among PMIA molecular chains, ND@PDA fillers, enriched with hydroxyl groups, facilitate the formation of additional hydrogen bonds with PMIA, generating a hydrogen bonding network. This network provides additional dipoles for overall polarization, enhances Young's modulus for electromechanical resistance, and suppresses dielectric loss upon temperature increase, thereby reducing conduction loss. Both experimental and simulation results indicate that this hydrogen bonding network is extremely stable at high temperatures, effectively promoting the decoupling enhancements of ɛ r and E b for high-temperature energy storage applications. [Display omitted] • PMIA-based composite film for high-temperature energy storage is reported. • Electrospinning evenly disperse fillers and hot-pressing consolidate the structure. • High-temperature stable hydrogen bonding network is observed. • Decoupling enhancements of ɛ r and E b are realized by H-bonds. • At 150 °C, the 1.0 wt% film shows a U e of 5.15 J/cm3 at η > 90 %. [ABSTRACT FROM AUTHOR]

As potential dielectric materials for capacitors, glass-ceramics exhibit significant promise in the realm of pulse power supply. Extensive research has been undertaken to explore the commendable voltage resistance and favorable dielectric properties of glass-ceramics. They exhibit a rapid charge and discharge rate. However, the limited energy storage density of glass-ceramics constrains their practical application. In this study, we focused on the preparation of CaO-SrO-Na 2 O-Nb 2 O 5 -SiO 2 (CSNNS) glass-ceramics through conventional melting and high-temperature crystallization processes. Our investigation delved into the impact of crystallization temperature on the phase composition, dielectric properties, and energy storage characteristics of the CSNNS glass-ceramics. The results indicate a direct correlation between the dielectric constant and dielectric loss, both exhibiting an upward trend with increasing crystallization temperature. Simultaneously, the microstructure of the glass-ceramics manifests signs of deterioration, characterized by larger grain size and heightened porosity, leading to a reduction in breakdown strength. At a crystallization temperature of 1100 °C, the CSNNS glass-ceramics demonstrated a remarkable combination of a high dielectric constant (∼280) and superior breakdown strength (481 kV/cm). The achieved maximum theoretical energy storage density reached 2.87 J/cm3. At an electric field of 100 kV/cm, the effective energy storage density is 0.23 J/cm3, and the energy storage efficiency is 72 %. These findings demonstrate the broad application potential of the CSNNS glass-ceramics in the domain of pulse power, highlighting their relevance for future developments in this field. [ABSTRACT FROM AUTHOR]

We developed high-performance SiO 2 -based low- ε r microwave dielectric composites via adding Sr 3 (PO 4) 2 and investigated their phase assemblages, sintering behaviors, microwave dielectric properties, thermal expansion coefficients (CTE), and mechanical strengths in this paper. Adding Sr 3 (PO 4) 2 into SiO 2 could successfully suppress the occurrence of microcracks in SiO 2 , tune the values of both temperature coefficient of resonant frequency (τ f) and CTE, and enhance the flexural strength of the composite simultaneously. The composite with 22.5 % volume fraction (V f) of Sr 3 (PO 4) 2 exhibits excellent combined properties with a low- ε r (∼5.35), high Q×f value (∼73,717 GHz), near-zero τ f value(∼ −1.1 ppm/°C), suitable high CTE value (∼17 ppm/°C), and acceptable high flexural strength (∼85Mpa) after sintering at the temperature of 1150°C/3 h. [ABSTRACT FROM AUTHOR]

High gradient insulators (HGI) consisting of ceramic and metallic alternating layer structure, have been shown to reduce surface breakdown occurrence in high voltage devices. Recently, the HGI's metal layers were replaced with high dielectric constant ceramics, creating dielectric high gradient insulators (DHGI) that were shown to outperform pure alumina analog. A 2-layer DHGI prototype manufactured by spark plasma sintering (SPS) demonstrated an increased surface breakdown field and fewer surface breakdowns during conditioning, compared to plain alumina. However, weak breakdowns at the opposite polarity were observed in the 2-layer structure. This study focuses on overcoming this issue by introducing a 3-layer design, with two high dielectric layers capping a plain alumina layer. Breakdown tests confirmed the elimination of weak breakdowns and improved dielectric strength, consistent with simulations predictions. Additionally, post-SPS air annealing was shown to be essential for removing adsorbed gases and recovering the high dielectric layers composition that changed during SPS. The annealed DHGIs were shown to reduce significantly the breakdown pulses during high-voltage conditioning. The 3-layer DHGI exhibited a 33.5 % higher breakdown field than plain alumina and a 13.5 % improvement over the 2-layer DHGI reported earlier. • A 3-layer DHGI eliminates weak breakdowns and improves dielectric strength. • The 3-layer DHGI improves breakdown field by 33.5 % relative to plain alumina. • The 3-layer DHGI improves breakdown field by 13.5 % compared to 2-layer DHGI. • Post-SPS air annealing reduces breakdown pulses significantly. [ABSTRACT FROM AUTHOR]

The glass-ceramics materials with the sample composition of xBi 2 O 3 -(0.40-x) B 2 O 3 -0.15ZnO-0.45P 2 O 5 (BBZP) (where x = 0.10, 0.15, 0.20, and 0.25) have been prepared using the conventional melt-quenching technique. Different nanocrystalline phases embedded inside the glass-ceramic matrix have been characterised by analysing x-ray diffraction spectra. The obtained density values as well as molar volume increases with the rise of bismuth content. The network structure of the glass ceramic samples has been investigated employing Raman spectroscopy. The DSC analysis reveals the decrease in Glass transition temperature (T g) (433K–416K), and crystallisation temperature (T c) (569K–556K) of the studied materials. The electrical properties of the samples have been investigated in the context of dielectric and modulus formalism. Different theoretical models have been employed to analyse the experimental data of dielectric and modulus spectra. The Nyquist plots of the materials have also been analyzed employing relevant models. It has been shown that the higher bismuth containing samples are highly dense with high thermal stability. Such materials also have high dielectric strength. Analysis of these performance indicators suggests the possible applications of these materials in electrochemical devices. [ABSTRACT FROM AUTHOR]

Transparent energy storage ceramics can balance energy storage characteristic and optical characteristic, and are expected to be used in areas such as transparent pulse capacitors. However, excellent energy storage performance and dramatic light transmittance are difficult to achieve simultaneously, limiting their subsequent development in the actual applications. The paper proposes a way to improve the transparent energy storage properties of KNN-based samples by regulating domain and grain size. By introducing an appropriate amount of Er 2 O 3 , fine cube grains and nanodomains are constructed. When doping 0.20 mol% Er 2 O 3 , the ceramics exhibited excellent recoverable energy storage density W rec ∼ 6.2 J/cm3, superior energy-storage efficiency η ∼ 71.3 %, large dielectric breakdown strength E b ∼ 670 kV/cm, ultrahigh hardness value of 6.9 GPa, and a maximum transmittance T ∼72 % at 880 nm. Dense microstructure, nanoscale grains, symmetrical lattice structure and relaxor behavior are the main reasons for obtaining high energy storage and transparency properties. • The W rec and η of x =0.20 sample are improved synergistically. • The energy storage property and light transmittance are improved synergistically. • The x =0.20 sample has excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Dielectric capacitors are crucial for power systems and hybrid vehicles. However, the polymer dielectric owns low energy density and cannot meet the demands of high-power and energy storage systems. The synergistic improvement of balance between dielectric constant (ε r) and breakdowon field strength (E b), along with better energy storage performance, is a primary focus of this study. This research employs a high ε r of P(VDF-TrFE-CFE) blended with linear PMMA to create a sandwich-structured composite via high-speed electrostatic spinning. Boron Nitride Nanosheets (BNNSs) for insulation and TiO 2 for polarization are used as fillers, aiming to achieve polymer-based composite with large energy storage density and minimal energy loss. Results show that the sandwich-structured composite with 0.5 vol.% BNNSs in outer layer and 3 wt.% TiO 2 in middle layer achieves the largest U e of 21.8 J/cm3 at the η of 74 %. This study broadens the application of novel dielectric materials in the fields of energy. The introduced sandwich structure dielectric composite by BNNS/TiO 2 co-doping process a stable energy storage performance and good cycle stability serving at severe running conditions. [Display omitted] • Interface-structured multilayer composite boosts insulation under high fields. • Uniform BNNS fillers in the matrix significantly enhance composite breakdown strength. • TiO 2 nanosheets in the middle layer increase polarization and dielectric constant. [ABSTRACT FROM AUTHOR]

Dielectric switching composites independent of electronic or ionic relaxation polarization are extremely rare but urgently in demand, typically for the stimulus-responsive electronics with high safety requirements. Herein, we demonstrate that it is feasible to create a bistable, abrupt, reversible, and self-supporting dielectric switching composite in the absence of a conducting constituent relying only on interfacial polarization and micro-interface modulation. This polarization modulation relies on the micro-interface evolution induced by the reversible migration of barium titanate nanoparticles. We observe a well-defined bistable dielectric switching behavior with excellent flexibility and strength and small dielectric loss, which occurs over a narrow temperature region of 5 ℃. There is a thermal hysteresis as wide as about 28 ℃ observed upon heating/cooling cycles. This work enables a comprehensive understanding of the dielectric switching mechanism and demonstrates that bistable dielectric switching can be achieved in mechanically tough composites with higher safety and lower power consumption. [Display omitted] • Mechanically tough dielectric switching composites without electrically conductive constituents. • Higher safety and lower power consumption by not relying on electronic or ionic relaxation polarization. • Bistable dielectric switching via interfacial polarization and micro-interface modulation. • Synchronization of dielectric switching, mechanical switching and thermal management capabilities. [ABSTRACT FROM AUTHOR]

Excellent energy storage performance of dielectric capacitor is critical in modern electronic devices and power systems. However, the key component of dielectric composite may fail to function properly under severe service conditions, such as elevated temperature and great applied electric field. Here, the linear dielectrics of PI and PESU with high glass transition temperature (T g) were proposed to improve the energy storage performance of composite, which hold the weakened carrier migration. The large band-gap of PESU and tight molecular chain of PI are beneficial for reducing leakage current density of composite, enhancing inter-molecular stability over a wide temperature and electric field range. Finally, the energy storage performance is improved by constructing a multi-layer structure with alternating outer layers. For instance, the discharge energy density (U e) of 0.4PI-0.6PESU composite reaches 6.38 J/cm3 at 700 kV/mm and 80 °C. Significantly, the U e of multi-layer 2/1/PVDF/1/2 composite is increased by 92.36 % at 80 °C and 400 kV/mm (from 2.88 J/cm3 to 5.54 J/cm3), and the efficiency (η) of it keeps at 68.5 %. Meanwhile, it owns a good cycle stability after 50,000 cycles with η > 90 %. This work provides a new direction of developing dielectric composite serving in severe service conditions for capacitors. • The electrostatic interaction between PESU and PI molecular chains reduces voids and hinders carrier migration. • The energy storage performance of the alternating stacked dielectric composite is improved at the elevated temperature. • The five-layer 2/1/PVDF/1/2 composite demonstrates a good cycle stability at severe running condition. [ABSTRACT FROM AUTHOR]

Lignocellulosic papers (LCP) are favored for electrical insulating applications due to their environmental friendliness, ease of processing, and cost-effectiveness. However, the loose structure and numerous pores inside LCP result in the poor mechanical and electrical insulating properties, posing challenges in meeting the requirements for the rapid upgrading of high-voltage electrical equipment. Herein, a 3D interconnective structure composed of 3D aramid nanofibers (ANF) and 2D carbonylated basalt nanosheets (CBSNs) is introduced to enhance the structure and the chemical bonding interactions of LCP. This is achieved by impregnating LCP into an ANF-CBSNs suspension, where the 3D interconnective ANF framework hosts numerous CBSNs. The resultant LCP/ANF-CBSNs (LCP/A-C) composite papers exhibit multilayered structure and multiple hydrogen-bonding interactions, demonstrating excellent mechanical and electrical insulating properties. Notably, the optimized LCP/A-C5 composite papers exhibit remarkable tensile strength (23.15 MPa) and dielectric breakdown strength (20.14 kV·mm−1), respectively, representing 229 % and 145 % increase compared to those of the control LCP. These impressive properties are integrated with excellent bending ability, outstanding high temperature resistance, exceptional volume resistivity, and low dielectric constant and loss, demonstrating their potential as highly promising electrical insulating papers for advanced high-power electrical equipment. [Display omitted] • A high-performance ANF-CBSNs suspension with a 3D interconnective structure is prepared as a structural reinforcement. • Incorporating ANF-CBSNs composites into LCP constructs multilayered structures and multiple hydrogen-bonding interactions. • The lignocellulosic composite papers exhibit excellent mechanical and electrical insulating properties. • The lignocellulosic composite papers demonstrate great high-temperature resistance properties. [ABSTRACT FROM AUTHOR]

• This study investigates how polymer/filler interphase affects dielectric properties in polymer nanocomposites. • Through the grafting of poly (butyl acrylate) chains onto the surface of rGO, and adding it to the synthesized copolymer matrices with varying comonomer ratios of butyl acrylate and methyl methacrylate, the interphase was systematically manipulated. • Enhanced dielectric permittivity and reduced loss in nanocomposites with optimized interfacial interactions were achieved. In this study, an innovative interfacial design strategy aimed to investigate the effects of interfacial interactions between the matrix and reduced graphene oxide (rGO) on the dielectric properties of nanocomposites. The polymer matrices with varying comonomer ratios of butyl acrylate and methyl methacrylate were synthesized to deliberately engineer diverse interfacial interactions with polymer-grafted reduced graphene oxide. Through this approach, fine-tuned interfacial interactions between the polymer matrix and polymer-grafted rGO were achieved, which was verified by FE-SEM, DSC, and DMTA analysis. Subsequently, the dielectric properties of the nanocomposites were investigated to elucidate the relationship between interfacial strength and dielectric efficiency. It was found that polymer nanocomposites with enhanced interfacial interactions exhibit higher dielectric permittivity compared to the neat matrix. This enhancement was attributed to the increased charge storage in the interfacial area and improved alignment of polarizable polymer chains in the interphase between the polymer matrix and polymer-grafted rGO. [Display omitted] [ABSTRACT FROM AUTHOR]

The study explores the use of polydopamine-functionalized hexagonal boron nitride (h-BNO@PDA) as a lubricant/insulator additive in polyalphaolefin (PAO6) oil. This article's novelty lies in the formulation of an innovative lubricant that is free from sulfated ash, phosphorus, and sulfur (SAPS), exhibiting super-lubrication and desirable dielectric properties under electrified conditions. The h-BNO@PDA nanolubricant is specifically designed to mitigate the negative effects of shaft currents and enhance powertrain lubrication for electric vehicles (EVs). Herein, the physicochemical, dielectric strength, and tribological properties of h-BNO@PDA nanolubricant are compared to commercial fully synthetic oil (ATF-6S) used in EVs. The SRV-IV tribometer was used to assess tribological performance under various currents (0–10 A). Subsequently, characterization techniques were utilized to illustrate wear mechanisms and explore tribochemical reactions. The h-BNO@PDA nanolubricant presented superior physicochemical and dielectric properties. The h-BNO@PDA nanolubricant reduced the friction coefficient by 18–20 % and the wear rate by 4–72 % compared to ATF-6S oil under electrified conditions at temperatures of 27 °C and 100 °C. These findings can be attributed to the positive effects of oxidational wear (Fe 3 O 4) and h-BNO@PDA on tribolayer formation under electrification conditions. Eventually, our findings will offer promising insights to enhance the durability of EVs powertrain. [Display omitted] • Novel SAPS-free lubricant for electrical vehicles (EVs) powertrain lubrication. • Wear and friction under electrification effects are studied by SRV-IV tribometer. • h-BNO@PDA nanolubricant improved anti-wear properties by up to 72 %. • h-BNO@PDA additive enhanced anti-decomposition and corrosion resistance properties. • Presenting positive effects of oxidational wear under electrification effects. [ABSTRACT FROM AUTHOR]