Dielectric nanocomposites are emerging as next-generation energy storage materials due to their applicability in advanced electronics, renewable energy systems, and electric vehicles. In this work, we report the rational molecular design, synthesis, and structure-property investigation of a BaTiO3/cellulose nanocrystal (CNC)-liquid crystal polymer (LCP) nanocomposite with enhanced dielectric performance. The hybrid platform integrates BaTiO3 nanoparticles dispersed within a cyanobiphenyl-based polyacrylate matrix (PAACB12-r-PAA), followed by in situ interlocking with CNCs. This biomaterial-supported anisotropic system, exploits both the permanent dipole of smectic cyanobiphenyl liquid crystalline mesogens and ordering of CNC-LC materials to induce hierarchical self-assembly and promote strong dielectric responses. Films are fabricated through hot-pressing at the liquid crystalline transition temperature (TLC), followed by rapid quenching to lock in the alignment. We systematically investigate the influence of processing parameters such as BaTiO3 concentration, LCP alignment, and thermal treatment on dielectric behavior. Temperature-controlled small-angle X-ray scattering (TSAXS), broadband dielectric spectroscopy, and microscopy are employed to correlate mesophase orientation, dispersion quality, and molecular interactions with the dielectric constant, breakdown strength, energy density, and dielectric loss. Our findings reveal that the liquid crystalline matrix not only enhances BaTiO3 dispersion and interfacial polarization but also facilitates structural ordering that improves the composite's dielectric performance. The permanent dipoles within the LCP matrix further augment polarization via Ti4+ displacement from the O2- octahedra in BaTiO3, offering tunable dielectric enhancement. This work establishes a general strategy for designing multifunctional dielectric nanocomposites by integrating mesogen alignment, nanofiller anisotropy, and optimized processing to achieve tunable dielectric performance for advanced electronic applications.

High‐temperature polymers with excellent dielectric and intrinsic self‐healing capabilities are essential for advanced electrical and electronic systems. However, existing design approaches for high temperature polymers rely on the incorporation of bulky phenyl groups in the mainchain, resulting in compromised dielectric performance and self‐healing due to π–π stacking and elevated element ratio of ( C + N + S )/( H + O ). Here, a molecular design strategy is reported for polyetherimides that synergistically integrates alicyclic linkages with large endcap structures to concurrently enhance dielectric and self‐healing properties. Among the synthesized materials, a novel polyetherimide featuring an alicyclic linkage and a 2,4,6‐tri‐tert‐butylaniline (tTBA) endcap achieves an exceptional discharged energy density of 8.2 J cm − 3 at 808 MV m −1 and 150 °C, a 4X improvement over existing polyetherimides. Mechanism studies reveal that alicyclic linkages facilitate optimal volatilization pathways during pyrolysis, with reduced char residue formation, to ensure robust self‐healing. This research provides a molecular‐engineering design framework for tailoring high‐temperature polymers with concurrently enhanced dielectric and self‐healing properties.

The self-assembled anisotropic coating modifies the surface defects of amorphous polymers, inhibiting charge injection and greatly improving the breakdown strength and storage efficiency.

Conductive Atomic Force Microscopy (C-AFM) was used to investigate if conductive by-products exist within surface tracks—closely related to electrical trees—that are generated by high-power surface flashover events on epoxy nanocomposites used in high-breakdown dielectric applications. Here, we show that topography measurements alone are insufficient to identify conductive surface tracks unambiguously. Instead, by mapping DC currents flowing into the sample from the scanned C-AFM tip, conductive tracks up to three orders of magnitude less resistive than adjacent epoxy nanocomposite material are revealed. Ohmic behavior was confirmed by systematically incrementing the applied voltage, thereby providing a unique method for directly quantifying and mapping the conductivity in electrical breakdown-induced surface tracks, with potential for future applications to the investigation of bulk electrical trees.

This study introduces a novel integrated laser powder bed fusion (LPBF) approach for fabricating highquality, ultra-high-temperature oxide eutectic ceramic coatings on superalloys to meet the critical demand for improved thermal barrier coatings in high-temperature applications. To resolve the interface bonding challenges between brittle ceramic coatings and ductile superalloys, this method employs two different laser sources: a short-wavelength fiber laser for fabricating the IN718 superalloy substrate and NiCoCrAlY bonding layer, and a long-wavelength CO2 laser for depositing oxide eutectic ceramic coatings. Additionally, the finite element modeling (FEM) is utilized to optimize the preparation of superalloy- ceramic coating composites using LPBF technology, revealing the temperature and stress field distributions during the fabrication process. The resulting in-situ eutectic composite ceramic coatings exhibit a bonding strength of about 29.3 N and a nanoscale microstructure with a eutectic spacing of 97 nm. In high-temperature water-oxygen corrosion tests at 10 0 0 degrees C, the coatings showed no signs of delamination. After 100 h of heat treatment at 500 degrees C, the microstructure experienced only a slight coarsening, maintaining its nanoscale structures. This LPBF fabrication method provides an effective approach for the rapid integrated manufacturing of oxide eutectic ceramic coatings on superalloy substrates, demonstrating significant potential for high temperature applications. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The ever-increasing applications of variable speed drives (VSDs) in electric motor-drive systems demand insulation systems that can withstand fast pulse repetitive voltage (FPRV) stress conditions characterized by high dv/dt and switching frequencies. However, conventional polymer dielectrics exhibit premature failure possibly due to partial discharge, local electric field distortion, dielectric heating and systematic overvoltage. In this work, we demonstrate a scalable surface engineering strategy using a montmorillonite (MMT) nanoclay coating to enhance the insulation performance of polyether ether ketone (PEEK) under FPRV. The 2D MMT coating forms a nacre-like microstructure that inhibits through-plane charge transport and promotes inplane charge dissipation. Dielectric characterization shows that the coating has a minimal impact on permittivity and loss tangent, while with significantly improved time-to-breakdown performance for PEEK under accelerated aging tests of bipolar 5.0 kV peak-to-peak, $1.2 \text{kHz}, 50 \%$ duty cycles. Surface potential decay measurements confirm the coating's ability to dissipate the surface charges. These findings demonstrate a promising and scalable pathway to improving the electrical insulation and reliability of polymer dielectrics for high-frequency, high-voltage power electronic applications.

Electrical treeing was studied to compare how proposed aerospace insulation material fluorinated ethylene propylene (FEP) behaves relative to current, standard insulation material cross-linked polyethylene (XLPE). Here we show that XLPE has better electrical treeing initiation voltages at both pressure conditions studied when compared to FEP; however, FEP has better partial discharge behavior. Since electrical treeing is a partial discharge driven process, it is crucial that insulation chosen for aircraft application are as resistant to partial discharge as possible. Future work should consider comparing both treeing initiation voltages and partial discharge behavior, as just one technique does not represent the wholistic behavior.

This study examines the morphological evolution of melt-cast Poly (ethylene terephthalate) (PET) thin films under nonlinear deformation strategies, specifically stretching and cycling, to analyze their structural, mechanical, and electrical properties. Capacitor-grade thin films were melt-cast and subjected to uniaxial deformation using an instrumented stretching machine that applied programmable deformations. During deformation, real-time mechano-optical data, including birefringence, true strain, and true stress, were collected above the glass transition temperature (Tg).Stress-induced crystallization emerged as the primary mechanism during stretching, as thermally induced crystallization was suppressed due to high viscosity in the rubbery temperatures near Tg. Strain oscillations after steady deformations at various strain levels promoted crystallization and relaxed oriented amorphous chains. This process enhanced crystalline orientation and crystallinity, particularly in stretching and oscillation tests compared to stretching and holding tests. At higher deformation levels, the orientation of amorphous domains transitioned to oriented crystalline structures. Increased crystallinity and crystalline and amorphous chain orientation enhanced electrical breakdown. The strain oscillation played a crucial role in promoting crystallinity enhancement while minimizing amorphous chain orientation, leading to lower electrical breakdown. These results highlight the substantial influence of the amorphous phase and its chain orientation on the electrical breakdown of PET films.

Biaxially oriented polypropylene (BOPP) thin film is the predominant dielectric material used in film capacitive energy storage for pulsed power engineering and power conversions due to its remarkable high dielectric strength and low conduction loss. However, the design rating of BOPP film capacitors in high power density conversion systems operated also under high temperature is still based on the empirical criteria due to the lack of systematic mechanism studies at elevated temperature. In this work, the temperature‐dependent electrical conduction in tenter and bubble BOPP films up to their breakdown strength was systematically studied using a specialised circuitry featuring dynamic gain‐controlled capacitive current cancellation. Both tenter and bubble BOPP films exhibit an extended trap‐limited conduction region at the high electric field, followed subsequently with a trap‐filled limited conduction until breakdown. This trap‐filled‐limited conduction presents characteristics of carriers transport with detrimental high mobility and soaring conduction loss. Overall, the shallow localised states revealed by the Arrhenius analysis, the large bandgap, and high barrier height of BOPP film together render its exceptional electrical integrity. In comparison, the enhanced crystallinity and larger crystallite sizes in tenter BOPP produced by the sequential stretching result in a higher upper operational temperature and slightly higher breakdown strength than bubble BOPP, suggesting the important role of processing induced enhancements to intrinsic properties of molecular origin. This study provides insights into the high‐field characteristics of BOPP films at elevated temperature with promising learning outcomes useful to the expedited designs of the next generation polymer films for capacitive energy storages.

The emergence of high‐density electronics in aerospace and renewable energies demands high temperature dielectrics. Molecular engineering represents a vital strategy for designing dielectric polymers, yet the influence of stereochemistry remains untapped. Herein, by designing halogen substituents of an aromatic pendant attached to a bicyclic mainchain, vicinal polydichloronorbornene (PDCNB) with a high glass‐transition temperature ( T g ) of 263 °C is obtained. Further study unveils the profound effect of stereochemistry on the properties of exo‐ and endo‐PDCNB. Both isomers show identical high T g and bandgap (4.3 eV), imparting PDCNBs with remarkable capacitive energy storage, outperforming existing polymers and nanocomposites with two orders of magnitude lower conduction at an ultra‐high temperature of 250 °C. Moreover, the effect of stereoisomerism is manifested in the differences in backbone spacing, π‐stacking, barrier height, and trap states, and the resulting distinct high field performance. Exo‐PDCNB displays an extremely low conduction of 6.8 × 10 −14 S m⁻ 1 at 200 m V m⁻ 1 and maintains a record charge‐discharge efficiency of 82% at 450 m V m⁻ 1 , while endo‐PDCNB exhibits a high breakdown strength of 600 m V m⁻ 1 with a remarkable discharged density of 4.47 J cm⁻ 3 , all at 250 °C. This study unleashes a stereochemistry‐based strategy with vicinal dichloro substitution to further boost the T g of polynorbornene for ultra‐high‐temperature applications.

Next-generation electrical and power electronic systems necessitate polymer dielectrics with high energy densities and high-temperature applicability. However, such ever-increasing performance demands result in exponential increases of leakage electrical conduction, which is fundamentally associated with thermally and electrically assisted charge injection and transport mechanisms. Here, we report a substantial improvement in high-temperature energy storage properties for polymer dielectrics with a bilayer nanocoating. Two-dimensional boron nitride and montmorillonite nanosheets were coated on the polymer surface, showing a synergetic effect on trapping and dissipating the hot carriers injected from electrodes. We obtain an ultrahigh discharged energy density of 5.5 J/cm3 with an efficiency exceeding 90 % at 150 degrees C. This bilayer nanocoating strategy provides a generalizable approach for designing high-performance polymer dielectrics via interfacial engineering.

While water may be stored in Venus' interior in the form of hydrous minerals, the velocity structure on Venus has been inferred based on anhydrous conditions. Due to its high decomposition temperature, tremolite could potentially store water on Venus, and thus, it is important to assess if the water-bearing tremolite could potentially have a distinct signal in velocity profiles of the Venusian lithosphere that future missions could measure. In this study, we measured the elastic properties of tremolite polycrystalline samples at high pressure up to 6 GPa using an ultrasonic interference method. Our results show that both VP and VS for tremolite increase linearly with pressure, and the values are much lower than those of nominally anhydrous minerals. The VP/VS ratio of 1.59-1.73 is less than that of most hydrous minerals. Combining the thickness of the crust and mineralogic models in previous studies, we attempt to build a possible wave velocity structure of Venus bearing tremolite deep to 100 km. Our results indicate that under cold temperature gradients, tremolite decomposes at 56 km resulting in a jump of 3.0% and 2.2% in VP and VS respectively, while under hot temperature gradients, tremolite decomposes at 35.2 km resulting in a jump of 3.1% and 2.2% in VP and VS respectively. When seismic velocity profiles for Venus become available through future missions, these theoretical profiles could provide insight into the potential presence of tremolite in the lithosphere of Venus and therefore the global water budget of the planet.

The growing demand for wearable devices has sparked a significant interest in ferroelectret films. They possess flexibility and exceptional piezoelectric properties due to strong macroscopic dipoles formed by charges trapped at the interface of their internal cavities. This review of ferroelectrets focuses on the latest progress in fabrication techniques for high temperature resistant ferroelectrets with regular and engineered cavities, strategies for optimizing their piezoelectric performance, and novel applications. The charging mechanisms of bipolar and unipolar ferroelectrets with closed and open-cavity structures are explained first. Next, the preparation and piezoelectric behavior of ferroelectret films with closed, open, and regular cavity structures using various materials are discussed. Three widely used models for predicting the piezoelectric coefficients (d33) are outlined. Methods for enhancing the piezoelectric performance such as optimized cavity design, utilization of fabric electrodes, injection of additional ions, application of DC bias voltage, and synergy of foam structure and ferroelectric effect are illustrated. A variety of applications of ferroelectret films in acoustic devices, wearable monitors, pressure sensors, and energy harvesters are presented. Finally, the future development trends of ferroelectrets toward fabrication and performance optimization are summarized along with its potential for integration with intelligent systems and large-scale preparation.

Greenhouse gas emission reduction is underway worldwide to mitigate the effects of global warming. Among the new initiatives, electrification of passenger airplanes could yield enormous economic and environmental benefits although a few key technology barriers remain. One main challenge is related to the insulation system. This is because insulation systems required for electric aircraft will need to withstand higher local electric fields and higher temperatures. Unfortunately, all polymeric insulation systems are subject to an aging degradation mechanism called electrical treeing, which can lead to electrical breakdown. The defect is exacerbated in areas of local high field, making it a crucial issue to understand in aircraft insulation. While this mode of tree-aging has been studied for centuries, the mechanism has been debated in the literature. Using new characterization techniques to shed new light on parts of the electrical treeing mechanism is key to new understanding that can lead to mitigation solution. One such new characterization technique is conductive atomic force microscopy (c-AFM). By using a conductive tip on the AFM, the electrical tree can be studied with respect to the electrical conductance of the interior walls and their speculated contribution to electrical tree propagation. This work used c-AFM to study an electrical tree on the surface of an insulation material to establish a baseline procedure in using this technique to study the walls of electrical trees. It was found that the c-AFM can provide conductivity results within and around an electrical tree.

The electronic band structure, especially the defect states at the conduction band tail, dominates electron transport and electrical degradation of a dielectric material under an extremely high electric field. However, the electronic band structure in a dielectric is barely well studied due to experimental challenges in detecting the electrical conduction to an extremely high electric field, i.e., prebreakdown. In this work, the electronic band structure of polymer dielectric films is probed through an in situ prebreakdown conduction measurement method in conjunction with a space-charge-limited-current spectroscopic analysis. An exponential distribution of defect states at the conduction band tail with varying trap levels is observed in accordance with the specific morphological disorder in the polymer dielectric, and the experimental defect states show also a favorable agreement with the calculated density of states from the density functional theory. The methodology demonstrated in this work bridges the molecule-structure-determined electronic band structure and the macro electrical conduction behavior with a highly improved understanding of material properties that control the electrical breakdown, and paves a way for guiding the modification of existing material and the exploration of novel materials for high electric field applications.

PCB layouts with different polygon shapes and insulation distances were prepared and their surface flashover voltage subjected to different ramping rates were measured at different temperatures and different low gas pressures for emulated high-altitude conditions. The dependence of the surface flashover voltage on effects of gas pressure, surface insulation distance, temperature, and polygon shape was studied. Modulation efforts which include tailoring the local surface conductivity and local topography modification were performed to increase the flashover of PCB, and the related mechanism was studied. The results showed that the voltage ramping rate plays an important role in determining flashover voltage. The flashover voltage is lower when the sample is subjected to a rapid voltage ramping rate than with a slow ramping rate. This phenomenon is more prominent towards ambient pressure. The increase in temperature results in a decrease in flashover voltage at 100 kPa, while at 20 kPa and 10 kPa, the influence of temperature on flashover becomes less significant. Through-holes designed in the PCB have a positive role in increasing flashover voltage at lower pressures. However, at 100 kPa, the holes no longer contribute to any higher flashover voltage. Modification of local surface conductivity has no contribution in increasing the flashover voltage, while a surface coating with a surface conductivity of 10 -10 S dramatically decreases the flashover voltage. The work presented in this paper provides a reference for the design and modification of PCB layouts for use in future aerospace hybrid propulsion systems.

Aircraft electrification poses new challenges to the safe design of the insulation system under harsh operating conditions. This study focuses on the investigation of electrical treeing, a precursor to electrical breakdown in the bulk of electric wires and cables, under emulated low pressure and high temperature for high density electrification at high altitude. It was found in a model insulation of cross-linked polyethylene (XLPE) that low pressure and high temperature significantly decreased the treeing initiation voltage and increased tree growth propagation rate. Moreover, the presence and size of artificial air gaps affected tree morphology, growth rate, and fractal dimension in a way that decreases insulation durability. The effect of pressure on treeing growth was studied by using the partial discharge (PD) measurements, which suggested lower pressure increased PD activities, with respect to the rate and magnitude of PDs during both stages of treeing initiation and propagation. This work could be used as a baseline for studying electrical treeing phenomenon at high altitudes with coupled high temperature-low pressure, to pave the way for the reliable design of insulation systems on the path towards aircraft electrification.