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Several research studies have investigated the degradation of BaTiO3-based dielectric capacitor materials, focusing on the impact of composition, defect chemistry, and microstructural design to limit the electromigration of oxygen vacancies under electric fields at finite temperatures. Electromigration can be a dominant mechanism that controls failure rates in the individual multilayer ceramic capacitor (MLCC) components in testing the reliability of failures with highly accelerated lifetime testing (HALT) to determine the mean time to failure of MLCCs surface mounted onto printed circuit boards (PCBs). Conventional assumptions often consider these failures as independent, with no interaction between components on the PCB. However, this study employs a Physics of Failure (PoF) approach to closely examine transient degradation and its impact on MLCC reliability, emphasizing thermal crosstalk and its influence on dependent and independent failure rates. Finite element analysis thermal modeling and infrared thermography were used to assess the impact of circuit layout and component spacing on heat dissipation and thermal crosstalk under various electrical stress conditions. The study distinguishes between dependent and independent failures under a HALT, quantified through a β′ factor reflecting common cause failures due to thermal crosstalk. Through a series of experimental and statistical analyses, the β′ factor is evaluated with respect to temperature, voltage, and component spacing. These insights highlight the importance of understanding the nature of the data in reliability testing of MLCCs and optimizing the layout design of high-density circuits to mitigate dependent failures, improving overall reliability and informing better design and packaging strategies. [ABSTRACT FROM AUTHOR]

Currently, sophisticated advanced electronics require ferroelectric materials with high dielectric response. Lead-free (1 − x)K 0.5 Na 0.5 NbO 3 -xLiNbO 3 (KNN-xLiN) ceramics with x = 0.01, 0.03, and 0.05 were produced using a solid-state method, resulting in a greater dielectric constant, a lower impedance, and an increased conductivity. Compared to conventional ferroelectrics, KNN-0.01LiN ceramics have a greater activation energy (E r e l ) of 1.33 eV and a large σ a c value of 10 − 3 − 10 − 2 S/m in the frequency range of 20 Hz–1 MHz. The peak that corresponds to the orthogonal–tetragonal (T O − T ) phase shifts toward the lower temperature side and the peak that corresponds to T T − C shifts toward the higher temperature side as dopant percentage increases in the KNN-xLiN ceramics. The observed data may provide light on a key member of the team involved in the creation of upgraded ferroelectrics with improved performance. This result sheds light on the process underlying the improved characteristics of K 0.5 Na 0.5 NbO 3 -based ceramics and may lead to the development of high performance ferroelectrics that will benefit a variety of functional materials. [ABSTRACT FROM AUTHOR]

We present a systematic approach for synthesizing 3D-printable all-dielectric devices. Inverse design approaches yield, in many cases, configurations with a continuous range of dielectric constant values. However, 3D printer resins usually provide a very limited set of such values; commonly, a single resin and air are the only available materials. We propose a methodology for transforming a device with a continuous range of material properties to a manufacturable one, while preserving the device's performance as close as possible to the continuous case. We develop an algorithm that takes the continuous range of dielectric constant profile as input and generates a binary and connected device that can be 3D-printed using a single resin. Our methodology advances state-of-the-art algorithms by using manufacturable configurations of prescribed local air/resin composition to realize each designed dielectric material instead of being limited to a predetermined shape. The additional degrees of freedom provided by our approach may be particularly useful in devices of conformal complex-shaped dielectric constant profiles. We demonstrate the proposed methodology by designing a 3D-printable wide-angle refraction metagrating with performance very close to the inversely designed device of a continuous dielectric constant profile. The approach can be adapted to accommodate three-dimensional devices and other applications. [ABSTRACT FROM AUTHOR]

Electromagnetic applications of composites often impose constraints on the internal electric fields, such as an upper limit on the field strength to prevent local heating or dielectric breakthrough. However, owing to heterogeneity, the local fields in a composite differ from those in a homogeneous material. Moreover, they are accessible neither by experiment nor by effective medium theories, at least for arbitrary microstructures. In this work, we use numerical simulations to evaluate the electric field distribution and the effective permittivity for 3D systems of monodisperse impenetrable spheres dispersed in a continuous matrix phase. We restrict ourselves to loss-free dielectric materials and to a random spatial distribution of particles. Samples are placed in a parallel plate waveguide and exposed to a transverse electromagnetic wave. The local field amplitudes are calculated via the finite element method and are normalized to those of a homogeneous sample exhibiting the same effective permittivity and geometry. We analyze the distribution of the local electric field strength in both constituents, namely, particles and matrix. Thus, we evaluate mean values and standard deviations as well as the field strengths characterizing the highest and lowest percentiles. Increasing particle concentration or permittivity enhances heterogeneity, and so the local electric field strength in some domains can become much higher than its average value. The methods we apply here can also be used in further investigations of more complex systems, including lossy materials and agglomerating particles. [ABSTRACT FROM AUTHOR]

Ultrathin (1–4 nm) films of wide-bandgap semiconductors are important to many applications in microelectronics, and the film properties can be sensitively affected by defects especially at the substrate/film interface. Motivated by this, an in vacuo atomic layer deposition (ALD) was developed for the synthesis of ultrathin films of Ga2O3/Al2O3 atomic layer stacks (ALSs) on Al electrodes. It is found that the Ga2O3/Al2O3 ALS can form an interface with the Al electrode with negligible interfacial defects under the optimal ALD condition whether the starting atomic layer is Ga2O3 or Al2O3. Such an interface is the key to achieving an optimal and tunable electronic structure and dielectric properties in Ga2O3/Al2O3 ALS ultrathin films. In situ scanning tunneling spectroscopy confirms that the electronic structure of Ga2O3/Al2O3 ALS can have tunable bandgaps (Eg) between ∼2.0 eV for 100% Ga2O3 and ∼3.4 eV for 100% Al2O3. With variable ratios of Ga:Al, the measured Eg exhibits significant non-linearity, agreeing with the density functional theory simulation, and tunable carrier concentration. Furthermore, the dielectric constant ε of ultrathin Ga2O3/Al2O3 ALS capacitors is tunable through the variation in the ratio of the constituent Ga2O3 and Al2O3 atomic layer numbers from 9.83 for 100% Ga2O3 to 8.28 for 100% Al2O3. The high ɛ leads to excellent effective oxide thickness ∼1.7–2.1 nm for the ultrathin Ga2O3/Al2O3 ALS, which is comparable to that of high-K dielectric materials. [ABSTRACT FROM AUTHOR]

This study explores various models of semiconductor dielectric functions, with a specific emphasis on the large wavenumber spectrum and the derivation of the screened exchange interaction. Particularly, we discuss the short-range effect of the screened exchange potential. Our investigation reveals that the short-range effect originating from the high wavenumber spectrum is contingent upon the dielectric constant of the targeted system. To incorporate dielectric-dependent behaviors concerning the short-range aspect into the dielectric density functional theory (DFT) framework, we utilize the local Slater term and the Yukawa-type term, adjusting the ratio between these terms based on the dielectric constant. Additionally, we demonstrate the efficacy of the time-dependent dielectric DFT method in accurately characterizing the electronic structure of excited states in dyes and functional molecules. Several theoretical approaches have incorporated parameters dependent on the system to elucidate short-range exchange interactions. Our theoretical analysis and discussions will be useful for those studies. [ABSTRACT FROM AUTHOR]

In recent years, the exploration of solar absorbers has grown in favor due to the scarcity of energy. Here, we propose an absorber with an array of a circular ring surrounding disk (RSD) for solar energy capture. The novel structure keeps above 93.5% absorption with an average absorption of 96.95% in wavelengths from 300 to 4000 nm. Meanwhile, the proposed absorber is advantageous in that the structure is generalizable to other metals and dielectric materials. Furthermore, the data results show that the absorber has polarization-independent properties as well as maintaining >90% absorption in the considered wavelength range up to an incidence angle of 52° and >95% absorption at large process tolerances. Finally, the excellent absorption under the AM1.5 solar spectrum demonstrates the RSD absorber's ability to capture solar energy. These results show the potential of the absorber for applications in electromagnetic invisibility cloaking, thermal emitters, and solar energy capture and conversion. [ABSTRACT FROM AUTHOR]

In a class of high quality (Q-) factor dielectric resonators with low radiative losses, including popular whispering-gallery mode (WGM) resonators with high azimuthal mode numbers, due to high confinement of modal field in dielectric, the Q-factor is limited by the value of inverse dielectric loss tangent of dielectric material. Metal enclosures necessary for device integration only marginally affect the Q-factor while eliminating the residual radiative loss and allowing the optimization of input and output coupling. While very high Q-factors ∼ 200 000 are available in sapphire WGM resonators in X-band, at millimeter wave frequencies increasing dielectric loss limits the Q-factor to much smaller values, e.g. ∼50000 and ∼25000 for quasi-TE and quasi-TM modes, correspondingly, at 36 GHz. The use of distributed Bragg reflection (DBR) principle allows to push modal energy outside dielectric while also isolating it from Joule losses in metallic enclosure walls. Very high Q ∼ 600 000 > --> t g δ has been demonstrated in X-band [C. A. Flory and R. C. Taber, IEEE Trans. Ultrason., Ferroelectr., Freq. Control 44, 486–495 (1997).] at the expense of impractically large dimensions. In this work, we report on the assembly and testing of a compact Ka-band sapphire distributed Bragg reflector cavity characterized with Q-factor seven times larger than one predicted by the material's dielectric loss at the frequency of interest. An intrinsic Q-factor of ∼ 200 000 is demonstrated at 36 GHz for the lowest order TM-mode of a sapphire DBR. The resonator has 50 cm 3 volume, smaller than previously demonstrated DBRs. [ABSTRACT FROM AUTHOR]

AgNbO3 (AN)-based lead-free antiferroelectric ceramics are widely studied for their use as dielectric capacitor materials. In this study, Eu3+-doped AN ceramics were prepared and the results show that Eu3+ diffused into the AN lattice. The ceramics were formed by M1 and M2 phases coexisting at room temperature, as distinct from the M1 (M: monoclinic) phase of pure AN. Electrical properties and structural characterization showed that the antiferroelectric stability of the ceramics increases with the increase in Eu3+ levels. At room temperature, Ag0.94Eu0.02NbO3 ceramic exhibited a good energy storage density of 5.3 J/cm3 and a high efficiency of 71.9%. When the temperature rises from room temperature to 140 °C, the efficiency of the sample decreases from 80.4% to 67.1% and Wr decreases from 2.1 to 2.0 J/cm3, which indicates that the sample has good temperature stability. The time constant (t0.9) of this sample was less than 60 ns and the power density (PD) was 51.3 MW/cm3, indicating excellent charge–discharge capabilities. This novel ceramic is expected to be used as a new dielectric capacitor material for pulsed power supplies. [ABSTRACT FROM AUTHOR]

Thermally stimulated discharge (TSD) technique is a traditional method in dielectric research, especially for electrets. However, in conventional open-circuit and short-circuit TSD techniques, it is difficult to distinguish the surface charge and body charge of dielectric materials. In particular with the test of polymer electrets, the deformation of the polymer film may take place during the measurement process, which will affect the accuracy of the experiment results. In this paper, a glass-assisting TSD (GA-TSD) technique is proposed to solve the above problems. The feasibility of the experimental technique is verified with the GA-TSD spectra of fluorinated ethylene-propylene copolymer electret films. In addition, their theory analysis is also accomplished. The influences of glass thickness, glass dielectric property, and metallizing on the glass on GA-TSD spectra are investigated. The results prove that the GA-TSD spectra can clearly distinguish the difference between surface charge and body charge according to the current direction. The quartz glass with the lowest dielectric constant is best suitable for the GA-TSD technique. The influence of the glass thickness and metallizing on the glass on GA-TSD spectra is little. [ABSTRACT FROM AUTHOR]

Electromagnetic metasurfaces can achieve effective control of electromagnetic waves and achieve effects such as blocking, enhancing, reflecting, transmitting, or deflecting electromagnetic waves, possessing electromagnetic properties that go beyond traditional materials. Existing research indicates that the dielectric substrate of metasurfaces has a significant impact on their electromagnetic properties. Increasing the substrate thickness will be beneficial for expanding the impedance bandwidth of the metasurface, and changes in dielectric constant will also have some impact on the operating frequency and bandwidth of the metasurface. A metasurface based on an air substrate was proposed through the research of dielectric materials. In addition, an ultrawideband, miniaturized, and high-gain metasurface antenna based on an air substrate is designed. The overall size of the designed antenna is 0.5λL × 0.5λL (where λL represents the wavelength at the lowest working frequency in free space). The measured results indicate that the proposed antenna exhibits a −10 dB impedance bandwidth of 74.3% (2.53–5.52 GHz) and a peak boresight gain of 10.1 dBi. [ABSTRACT FROM AUTHOR]

Glassy films of methyl-m-toluate have been vapor deposited onto a substrate equipped with interdigitated electrodes, facilitating in situ dielectric relaxation measurements during and after deposition. Samples of 200 nm thickness have been deposited at rates of 0.1 nm/s at a variety of deposition temperatures between 40 K and Tg = 170 K. With increasing depth below the surface, the dielectric loss changes gradually from a value reflecting a mobile surface layer to that of the kinetically stable glass. The thickness of this more mobile layer varies from below 1 to beyond 10 nm as the deposition temperature is increased, and its average fictive temperature is near Tg for all deposition temperatures. Judged by the dielectric loss, the liquid-like portion of the surface layer exceeds a thickness of 1 nm only for deposition temperatures above 0.8Tg, where near-equilibrium glassy states are obtained. After deposition, the dielectric loss of the material positioned about 5–30 nm below the surface decreases for thousands of seconds of annealing time, whereas the bulk of the film remains unchanged. [ABSTRACT FROM AUTHOR]

Antiferroelectric and ferroelectric materials are prominent non-linear dielectric materials with significant applications across various fields. To fully understand their electrical properties, it is crucial to accurately discriminate the two phases, especially in compositions with the coexistence of antiferroelectric and ferroelectric phases. In this study, we propose an easy method for differentiating domain structures from phase coexistence based on split outskirt reflections. The proposed method addresses existing limitations in the spatial phase distribution and lays the groundwork for understanding their structure–property relationships. [ABSTRACT FROM AUTHOR]

This paper reviews the evolution of the charge pumping (CP) technique and its applications from the micrometer-scale to the atomic-scale device era. We describe the more significant milestones of the CP technique (CPT) over the past couple of decades, giving insight into its potentialities. We start with the most popular one "traditional or conventional CP" and follow up with its different extensions in various fields like transistor reliability and radiation damage characterizations in devices fabricated with old and new semiconductor and dielectric materials. We show its easy adaptability for transistors with specific geometries. Advantages, weaknesses, as well as future tendencies of CPT and its variants, are also discussed. [ABSTRACT FROM AUTHOR]

In order to meet the application requirements in the field of advanced pulse power capacitors, the energy storage performance of dielectric materials urgently needs to be enhanced. Due to the novel high-entropy effects being beneficial for improving energy storage performance, entropy engineering has received widespread attention in dielectric energy storage materials. Herein, CaHfO 3 modified (Bi 0.5 Na 0.5)TiO 3 -based ceramics, (0.95- x)[(0.6BNT-0.4SBT)]-0.05La- x CaHfO 3 (BNT-SBT-La- x CH) (0.01 ≤ x ≤ 0.10) ceramics, were designed by entropy engineering strategy and synthesized via a hydrothermal-assisted method. It is found the introduction of CaHfO 3 enhances the configuration entropy and promotes the generation of high-entropy ceramics. The enhancement of configuration entropy leads to stable single phase structure, reduction of grain size, formation of polar nanoregions, enhancement of dielectric relaxation behavior, expansion of band gap, and increase in resistivity, resulting in large E b and η. Accordingly, BNT-SBT-La-0.07CH high-entropy ceramic displays superior energy storage performance (W rec = 6.30 J/cm3, η = 86.5 %) under a great E b of 554 kV/cm along with good thermal, frequency, and cycle stability. These results confirm that entropy regulation provides a feasible way to produce high-performance energy storage ceramics. [ABSTRACT FROM AUTHOR]

Due to its excellent insulativity, thermal conductivity, chemical inertness and ultraflat surface, multilayer hexagonal boron nitride (h-BN) has become a favorable dielectric for two-dimensional materials or other conventional semiconductors. Multilayer h-BN can also serve as a functional material in deep ultraviolet optoelectronic or novel memory devices. However, the utilization of h-BN in electronic and optoelectronic applications has been severely impeded by the challenge of preparing large-area multilayer thin films. In this work, we achieved the controlled synthesis of centimeter-scale multilayer h-BN using a space confined route within an atmospheric pressure chemical vapor deposition (APCVD) system. Using thorough material characterization, the uniformity of multilayer h-BN is identified. We find that the thickness of multilayer h-BN can be fine-tuned with APCVD parameters and the growth mechanism in the confined space is systematically scrutinized. The multilayer h-BN thin film is further used as the gate dielectric for a hydrogen-terminated diamond field effect transistor (FET), which exhibits comparable performance with the devices with common dielectrics. Our work provides a novel strategy for the large-scale synthesis of multilayer h-BN thin films, paving the way for realizing its full potential in a panoply of applications. [ABSTRACT FROM AUTHOR]

Dielectric capacitors with ultrahigh power density have emerged as promising candidates for essential energy storage components in electronic and electrical systems. They enable enhanced integration, miniaturization, and lightweight design. However, the development of dielectric materials for cutting-edge energy storage applications has been significantly limited by their low recoverable energy storage density (Wrec) and energy efficiency (η), especially at moderate electric fields. In this study, we fabricated 0.85K0.5Na0.5NbO3-0.15Sr0.7Nd0.2ZrO3 ceramics with an outstanding energy storage performance (Wrec ~ 7 J cm−3, η ~ 92% at 500 kV cm−1; Wrec ~ 14 J cm−3, η ~ 89% at 760 kV cm−1). The exceptional energy storage performance can be primarily attributed to the heterogeneous structure, where orthorhombic and tetragonal polar nanoregions are embedded in a cubic matrix. This work provides a good paradigm for designing dielectric materials with ultrahigh energy storage density and excellent energy efficiency at a moderate applied electric field, aligning with the stringent demands for advanced energy storage applications. The authors propose a design strategy for lead-free relaxors, characterized by a heterogeneous structure that is constructed through a multi-scale process, resulting in high energy storage performance. [ABSTRACT FROM AUTHOR]

Colossal permittivity (CP) materials, particularly co–doped TiO2 ceramics, have garnered significant attention for their potential in high–performance ceramic capacitors. However, understanding the origin of CP remains a challenge, with the role of doping ratios between acceptor and donor ions largely underexplored. This study addresses this gap by systematically investigating the effects of Ga3+ concentrations on the microstructure and CP of GayNb0.025Ti0.975-yO2, prepared via the solid–state reaction method. The sintered ceramics exhibited a dense rutile TiO2 phase with increasing grain sizes and oxygen vacancies. Notably, CP values as high as 105 were achieved at Ga3+/Nb5+ ratio < 1.0. Optimal dielectric properties were observed at Ga3+/Nb5+ = 1.0, yielding a CP of 6.4 × 104 and a loss tangent < 0.03, surpassing the performance of many existing CP materials. Impedance spectroscopy revealed distinct electrical heterogeneity, with conductive grains and highly resistive grain boundaries with activation energies > 1.0 eV. Ceramics with 5% Ga3+ doping showed diminished CP due to the absence of semiconducting grains. The findings suggest that CP originates from the internal barrier layer capacitor. This study not only elucidates the crucial role of doping ratios in tailoring CP but also establishes a pathway for developing advanced dielectric materials with superior performance for ceramic capacitors. [ABSTRACT FROM AUTHOR]

The experiment investigated the dielectric properties of copper ferrite nanoparticle-doped cotton and cotton–polyester mixture and observed the higher dielectric permittivity of cotton–copper ferrite nanoparticles mixture than the cotton–polyester–copper ferrite nanoparticles mixture. This work describes the effects of copper ferrite nanoparticles on the dielectric properties of cotton and cotton–polyester mixture theoretically. The real and imaginary parts of the complex dielectric permittivity as function of temperature and concentration of copper ferrite nanoparticles are calculated. The decrease of dielectric permittivity of cotton–copper ferrite nanoparticles mixture and cotton–polyester–copper ferrite nanoparticles mixture with the increase of frequency has been observed. The comparison between theoretical and experimental results has been presented. [ABSTRACT FROM AUTHOR]

Flexible polymeric materials including dielectric thermal interface materials (TIMs) used in integrated circuits and other high frequency applications are exposed to extreme thermal and electrical conditions during their service life. Insight into the in‐use thermal stability and material lifetime is valuable to maintaining performance durability and preventing premature failure in actual end use. Herein, the thermal stability of polytetrafluoroethylene (PTFE), modified PTFE and their nanocomposites with recent generation boron nitride nanobarbs (BNNBs) was investigated based on lifetime prediction from thermogravimetric analysis and tensile strength deterioration of heat‐aged samples. Additionally, thermal degradation kinetics and mechanism was investigated using the model‐free advanced isoconversional method based on changing activation energy. The result shows that BNNB extends the lifetime of the PTFE by an order of magnitude. The degradation mechanism proposed from TGA‐MS result is supported by the multistep degradation mechanism identified in the kinetic computation. These results are valuable for predicting materials' in‐use lifetime to avoid premature failure. [ABSTRACT FROM AUTHOR]

Fluorinated nitriles have been proposed as low-global-warming-potential substitutes for industrial applications such as plasma etching and as dielectric materials in high-voltage equipment. FT-IR spectroscopy was used to measure the radiative efficiency of CH2FCN and its reactivity towards Cl and OH radicals, and to determine products from the Cl reaction. Relative rate experiments yielded rate constants for Cl and OH reactions of (2.1 ± 0.3) × 10−14 and (7.0 ± 1.0) × 10−14 cm3 molecule−1 s−1, respectively. The estimated atmospheric lifetime of CH2FCN with respect to radical attack was estimated to be 0.45 years, which, combined with the radiative efficiency of 0.042 W m−2 ppb−1, implies a 100-year global warming potential of 20. FCOCN was observed as the only organic product of the Cl-atom reaction in air, consistent with a dominant role for H-abstraction. Absolute infrared cross-sections for FCOCN were determined, to assist future experiments where this molecule may be formed. Quantum calculations at the CBS-APNO//B2PLYP-D3/cc-pVTZ level indicate similar energy barriers to addition and abstraction for OH radical attack, but the looser transition state and greater opportunity for tunneling also favor abstraction in this case. [ABSTRACT FROM AUTHOR]

The burgeoning requirement for compact electronic devices has intensified research into lead‐free dielectric ceramics that offer superior recoverable energy storage density and efficiency at low electric fields. In this study, we report the synthesis of Nd3+‐doped (Bi0.4K0.2Na0.2Sr0.2)TiO3 perovskite ceramics via the solid‐state reaction technique. The synthesized ceramics adopted a tetragonal crystal structure. As the concentration of Nd3+ ions increased, both the maximum dielectric constant (εm) and its corresponding temperature (Tm) decrease. The incorporation of Nd3+ ions perturbed the long‐range ferroelectric order, leading to diminished maximum polarization (Pm) and remanent polarization (Pr). The ceramics achieved optimal properties with 12 mol% Nd3+ doping, showcasing a significant recoverable energy storage density of 1.50 J/cm3 at a low electric field of 140 kV/cm, along with an exceptional storage efficiency of 94.6%. This research not only highlights a promising candidate for dielectric materials in low electric field applications but also introduces an innovative approach to enhance energy storage performance. [ABSTRACT FROM AUTHOR]

The literature reports highlight the transmission field (B1+) uniformity and efficiency constraints of cardiac magnetic resonance imaging (MRI) at ultrahigh magnetic fields (UHF). This simulation study proposes a 3D Metamaterial (MM) to address these challenges. The study proposes a 3D MM consisting of unit cells (UC) with split ring resonator (SRR) layers immersed in dielectric material glycerol. Implementing the proposed MM design aims to reduce the effective thickness and weight of the dielectric material while shaping B1+ and improving the penetration depth. The latter is dictated by the chosen array size, where small local UC arrays can focus B1+ and larger UC arrays can increase the field of view, at the cost of a lower penetration depth. Designing RF antennas that can effectively transmit at 21.0 T while maintaining patient safety and comfort is challenging. Using Self-Grounded Bow-Tie (SGBT) antennas in conjunction with the proposed MM demonstrated enhanced B1+ efficiency and uniformity across the human heart without signal voids. The study employed dynamic parallel transmission with tailored kT points to homogenize the 3D flip angle over the whole heart. This proof-of-concept study provides the technical foundation for human cardiac MRI at 21.0 T. Such numerical simulations are mandatory precursors for the realization of whole-body human UHF MR instruments. [ABSTRACT FROM AUTHOR]

In this paper, a modified Shooting and Bouncing Ray (SBR) method based on high-order impedance boundary conditions (HOIBCs) is proposed to analyze the electromagnetic (EM) scattering from electrically large three-dimensional (3D) conducting targets coated with radar-absorbing material (RAM). In addition, the edge diffraction field of coated targets is included in the calculation to improve the accuracy of the calculation. Firstly, the SBR method based on the bidirectional tracing technique is presented. It is concluded that the calculation of the scattered field of the coated targets requires the determination of the reflection coefficients on the coated surface. The reflection coefficients of the coated targets are then derived using HOIBC theory. Finally, the equivalent edge current (EEC) of the impedance wedge is derived by integrating the UTD solutions for the impedance wedge diffraction with the impedance boundary conditions. The simulation results show that the proposed method improves computational efficiency compared to MLFMA while maintaining accuracy. Furthermore, the RCS characteristics of targets coated with different RAMs, different coating thicknesses and with different angles of incidence were compared, as well as the RCS results of coated targets with those of conventional perfect electrical conductor (PEC) targets. [ABSTRACT FROM AUTHOR]

In the power system, transformers are crucial electrical equipment that require an insulator or dielectric material, such as paper immersed in insulating oil, to prevent electrical contact between components. The dissolved gas analysis (DGA) test is important for diagnosing and determining the maintenance recommendations for transformers. The duval triangle method (DTM) is commonly used to identify faults in transformers. The data used in this article are from DGA test of power transformers in East Java and Bali transmission main unit (UIT JBM). The DGA data were analyzed based on the IEEE C57.104-2019 standards, and by using the developed random forest (RF) classifier-based DTM for easier software implementation and better accuracy. The results of fault identification in 6 transformers case study showed a low-thermal fault (T1)<300 ℃ in transformer 1, where methane gas increased, stray gassing (S) in transformer 5 due to escalating hydrogen gas production, overheating (O)=250 ℃ indicated in transformers 2 and 6 due to rising ethane gas production. Transformers 3 and 4 were found in normal condition. This fault identification is done to enhance the accuracy of maintenance recommendation action based on DGA. [ABSTRACT FROM AUTHOR]

Understanding the dielectric properties of materials in the THz frequency range is crucial for the advancement of THz devices. Despite their significance, the dielectric characteristics of zirconium carbide (ZrC) within this frequency range remain underexplored, in particular the impact of surface carbon and oxide layers typically found on carbide particles. While traditional studies mainly focus on particle size, this study emphasizes the pivotal role of particle morphology in determining dielectric properties. Milling was employed to increase the surface exposure of ZrC particles, which were initially covered with layers of carbon and oxides. The dielectric parameters, derived from experimental THz time-domain spectroscopy (THz-TDS) data, indicated that increased milling led to improved energy storage capabilities. This enhancement is attributed to increased electronic polarizability and charge disorder-induced ionic polarization due to the increased surface exposure. Furthermore, the dielectric properties displayed reduced dispersion after further milling attributed to the uniform particle sizes and shapes achieved through this process. Our findings underscore the critical influence of surface carbon and oxide layers on the dielectric properties of ZrC and similar carbide particles—an aspect often overlooked in studies that focus solely on particle size and shape, ignoring the distinct dielectric contributions of each surface layer. [ABSTRACT FROM AUTHOR]

In this work, dense CdCu3(Al 1 ∕ 2 Ta 1 ∕ 2 ) x Ti 4 − x O 1 2 ceramics were prepared by a conventional solid phase method. The effect of Al 3 + /Ta 5 + dopants on the dielectric properties of CdCu3Ti4O 1 2 ceramics was systematically investigated. Upon Al 3 + /Ta 5 + co-doping, the dielectric properties of CdCu3(Al 1 ∕ 2 Ta 1 ∕ 2 ) x Ti 4 − x O 1 2 were significantly enhanced. Particularly, the CdCu3(Al 1 ∕ 2 Ta 1 ∕ 2 ) 0. 0 5 Ti 3. 9 5 O 1 2 material displays a decent dielectric property, where dielectric constants ( ε r ∼ 2 7 1 8 1), loss tangent (tan δ ∼ 0. 0 6 9) at a test frequency of 1 kHz are able to satisfy the application temperature requirement of the Y6R capacitor. Surprisingly, the refined grains resulting from Al 3 + /Ta 5 + co-doping lead to heightened resistance at grain boundaries, which is closely associated with enhanced dielectric properties. Meanwhile, the giant dielectric property of the materials can be attributed to the effect of the internal barrier layer capacitance. The obtained results are expected to provide a new idea for obtaining high dielectric constant and low loss tangent in CdCTO-based materials and promote the practical application of such materials. [ABSTRACT FROM AUTHOR]

A broadband microwave composite metamaterial absorber based on the Debye model, consisting of triple dielectric loss layers and different-ordered metallic fractal pattern vertical layers, has been proposed. The research results show that when all the three dielectric layers are silicon carbide fiber (SiCf), the composite absorber presents two intense absorption bands with a bandwidth of 5.44 GHz. The length (l) of the metallic pattern and thickness (t) of the top dielectric layer can effectively regulate the reflection loss performance. Additionally, the effective absorption bandwidth increases to 13.44 GHz when the relative absorption bandwidth reaches about 119.15% by replacing SiCf at the top dielectric layer with the dielectric loss materials which satisfy the Debye model. The research results show that the absorption bandwidth obviously increases with dielectric loss materials of distinct Imε. Furthermore, the proposed fractal pattern shows robustness to the variation of complex permittivity spectrum, expanding the range of suitable dielectric materials for composite broadband metamaterial absorbers. [ABSTRACT FROM AUTHOR]

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Atomically flat two-dimensional networks of boron are attracting attention as post-graphene materials. An introduction of cations between the boron atomic layers can exhibit unique electronic functions that are not achieved by neutral graphene or its derivatives. In the present study, we propose a synthesis strategy for ion-laminated boron layered materials in a solution phase, which enables the preparation of analogs by changing the alkali-metal species. The introduction of large cations extends the thermal range of the liquid-crystal phases because of weakened ionic interactions between borophene-like layers. An investigation of the capacitance of ion-laminated structures revealed a 105-fold or better increase in capacitance when the borophene-like materials were introduced between electrodes. That is difficult for general materials since the dielectric constant of common materials is below several thousand. Liquid crystals with a single-layered boron network and interlayer alkali cations have been developed to enhance capacity between electrodes. Their switching functionality via phase transitions has also been demonstrated. [ABSTRACT FROM AUTHOR]

Graphene-based dielectric materials, known for their high conductivity, hold promise for electromagnetic shielding, yet face limitations due to production challenges. To address this, we employed homogenization and ultrasound techniques to disrupt van der Waals bonding, followed by the addition of cellulose as a barrier to inhibit particle aggregation. Graphene nanosheets were layered through screen-printing techniques. By subjecting the structure to an annealing process that carbonized the barrier, graphene nanosheets were brought into contact, establishing an electron hopping pathway. This process led to a significant surge in conductivity, jumping from 23.8 to 633.0 S/cm. Leveraging the superior conductivity induced by graphene nanosheets compaction and reduced defects, the resulting printed films, with a thickness of 15.8 μm, achieved an electromagnetic interference shielding effectiveness (EMI SE) of 30.8 dB, and with a thickness of 7.8 μm, demonstrated a high absolute shielding effectiveness (SSE/t) of 25571 dB cm2 g−1. Our findings present a viable strategy for enhancing shielding capabilities of other 2D materials such as MXenes and transition metal sulfides (TMDC) [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials have been identified as promising candidates for future electronic devices. However, high dielectric constant (κ) materials, which can be integrated with 2D semiconductors, are still rare. Here, we report a hydrate-assisted thinning chemical vapor deposition (CVD) technique to grow manganese oxide (Mn3O4) single crystal nanosheets, enabled by a strategy to minimize the substrate lattice mismatch and control the growth kinetics. The material demonstrated a dielectric constant up to 135, an equivalent oxide thickness (EOT) as low as 0.8 nm, and a breakdown field strength (Ebd) exceeding 10 MV/cm. MoS2 field-effect transistors (FETs) integrated with Mn3O4 thin films through mechanical stacking method operate under low voltages (<1 V), achieving a near 108 Ion/Ioff ratio and a subthreshold swing (SS) as low as 84 mV/dec. The MoS2 FET exhibit nearly zero hysteresis (<2 mV/MV cm⁻¹) and a low drain-induced barrier lowering (~20 mV/V). This work further expands the family of 2D high-κ dielectric materials and provides a feasible exploration for the epitaxial growth of single-crystal thin films of non-layered materials. High dielectric constant (κ) materials compatible with van der Waals materials are desired to promote the development of 2D electronics. Here, the authors report a method to grow Mn3O4 nanosheets exhibiting κ up to 135 and equivalent oxide thickness down to 0.8 nm, enabling the fabrication of high-performance 2D MoS2 transistors. [ABSTRACT FROM AUTHOR]

This paper addresses the author's current understanding of the physics of interactions in polymers under a voltage field excitation. The effect of a voltage field coupled with temperature to induce space charges and dipolar activity in dielectric materials can be measured by very sensitive electrometers. The resulting characterization methods, thermally stimulated depolarization (TSD) and thermal-windowing deconvolution (TWD), provide a powerful way to study local and cooperative relaxations in the amorphous state of matter that are, arguably, essential to understanding the glass transition, molecular motions in the rubbery and molten states and even the processes leading to crystallization. Specifically, this paper describes and tries to explain 'interactive coupling' between molecular motions in polymers by their dielectric relaxation characteristics when polymeric samples have been submitted to thermally induced polarization by a voltage field followed by depolarization at a constant heating rate. Interactive coupling results from the modulation of the local interactions by the collective aspect of those interactions, a recursive process pursuant to the dynamics of the interplay between the free volume and the conformation of dual-conformers, two fundamental basic units of the macromolecules introduced by this author in the "dual-phase" model of interactions. This model reconsiders the fundamentals of the TSD and TWD results in a different way: the origin of the dipoles formation, induced or permanent dipoles; the origin of the Wagner space charges and the Tg,ρ transition; the origin of the TLL manifestation; the origin of the Debye elementary relaxations' compensation or parallelism in a relaxation map; and finally, the dual-phase origin of their super-compensations. In other words, this paper is an attempt to link the fundamentals of TSD and TWD activation and deactivation of dipoles that produce a current signal with the statistical parameters of the "dual-phase" model of interactions underlying the Grain-Field Statistics. [ABSTRACT FROM AUTHOR]

We report on a procedure for extracting the SPICE model parameters of a RADFET sensor with a dielectric HfO2/SiO2 double-layer. RADFETs, traditionally fabricated as PMOS transistors with SiO2, are enhanced by incorporating high-k dielectric materials such as HfO2 to reduce oxide thickness in modern radiation sensors. The fabrication steps of the sensor are outlined, and model parameters, including the threshold voltage and transconductance, are extracted based on experimental data. Experimental setups for measuring electrical characteristics and irradiation are described, and a method for determining model parameters dependent on the accumulated dose is provided. A SPICE model card is proposed, including parameters for two dielectric thicknesses: (30/10) nm and (40/5) nm. The sensitivities of the sensors are 1.685 mV/Gy and 0.78 mV/Gy, respectively. The model is calibrated for doses up to 20 Gy, and good agreement between experimental and simulation results validates the proposed model. [ABSTRACT FROM AUTHOR]

This paper introduces a novel method for measuring the dielectric permittivity of materials within the microwave and millimeter wave frequency ranges. The proposed approach, classified as a guided wave transmission system, employs a periodic transmission line structure characterized by mirror/glide symmetry. The dielectric permittivity is deduced by measuring the transmission properties of such structure when presence of the dielectric material breaks the inherent symmetry of the structure and consequently introduce a stopband in propagation characteristic. To explore the influence of symmetry breaking on propagation properties, an analytical dispersion equation, for both symmetries, is formulated using the Rigorous Coupled Wave Analysis (RCWA) combined with the matrix transverse resonance condition. Based on the analytical equation, an optimization procedure and linearized model for a sensing structure is obtained, specifically for X-band characterization of FR4 substrates. The theoretical results of the model are validated with full wave simulations and experimentally. [ABSTRACT FROM AUTHOR]

xTiO2-(1-x)SiO2 (x = 2.9~8.2 mol%) glass specimens were synthesized using the flame hydrolysis technique. This study aimed to elucidate the influence of TiO2 incorporation on the optical characteristics, defect behavior, and microwave dielectric performance of these materials. UV–vis and near-infrared spectroscopic analyses were employed to investigate the hydroxyl and optical bandgap properties. Electron paramagnetic resonance (EPR) and AC impedance spectroscopy were utilized to examine oxygen vacancies, Ti3+ defects, and their respective behaviors. The findings revealed that, with increasing TiO2 content, the generation and migration of defects became more favorable, consequently leading to higher dielectric losses. The imaginary component of the electric modulus experimental data was fitted using the modified Kohlrausch–Williams–Watts (KWW) function, while the frequency-dependent AC conductivity was analyzed using the Jonscher power law. The calculated activation energy exhibited a decreasing trend with increasing TiO2 content, consistent with the characteristics of doubly ionized oxygen vacancies, suggesting the involvement of identical charge carriers in the relaxation and conduction mechanisms. Notably, the 8.2TiO2–91.8SiO2 glass specimen demonstrated exceptional microwave dielectric performance, exhibiting εr = 4.13, Q × f = 57,116 GHz, and τf = −4.32 ppm/°C, rendering it a promising candidate for microwave substrate applications. [ABSTRACT FROM AUTHOR]

In this article, a compact triple‐band frequency‐tunable (FT) hexagonal‐shaped graphene antenna through a machine learning (ML) approach for terahertz (THz) application is presented. The proposed THz antenna is designed on a polyamide (∈r=3.5$$ {\in}_r=3.5 $$) substrate with a thickness of 10 μm, and graphene is used as an antenna radiator. The size of the substrate is 38 × 46 μm2. The FT is achieved by changing the chemical potential of graphene material. The performance of the proposed THz antenna has been investigated, and the impacts of several conducting materials like gold, aluminum, copper, and graphene and dielectric materials like Rogers RT/duroid 5880, polyamide, quartz, and SiO2 are explored. The proposed THz antenna provides three operating bands. The frequency of operation in Band‐1 is 2.51–5.05 THz, Band‐2 is 5.99–7.43 THz, and Band‐3 is 7.94–9.63 THz. The bandwidth in Band‐1, Band‐2, and Band‐3 are 2.54, 1.44, and 1.69 THz, respectively. The % of impedance bandwidth in Band‐1, Band‐2, and Band‐3 are 67.19%, 24.02%, and 21.28% respectively. The proposed antenna has a maximum peak gain of 5 dBi. The proposed antenna is optimized through various ML algorithms like random forest (RF), extreme gradient boosting (XGB), K‐nearest neighbor (KNN), decision tree (DT), and artificial neural network (ANN). The RF algorithm gives more than 99% accuracy compared to other ML algorithms and accurately predicts the S11 of the proposed antenna. The proposed THz antenna would be suitable for applications related to imaging, medical, sensing, and ultra‐speed short‐distance communication applications in the THz region. [ABSTRACT FROM AUTHOR]

High‐frequency dielectric materials have been widely and rapidly applied in areas such as automotive radar, Internet of Things, artificial intelligence, and quantum computing. Currently, the challenge in high‐frequency dielectric materials lies in reducing the dielectric constant (Dk) and dielectric loss (Df) without sacrificing its mechanical properties. This study addresses this challenge by introducing air, as the most common "low dielectric factor," into the polymer matrix in the form of hollow glass microspheres. Meanwhile, the reactive vinyl groups were also introduced onto the surface of the hollow glass microspheres, enabling an interfacial chemical reaction between the side vinyl groups of polybutadiene and its surface so that the organic–inorganic interface compatibility and interface peel strength are simultaneously improved. Consequently, the minimum Dk of 1.29 and Df of 0.0012 in 3–18 GHz are achieved, and the interface peel strength also reaches 0.65 N/mm. Molecular dynamics simulations, analysis of dielectric properties, and interface peel strength reveal the influence of hollow glass microspheres' morphology and chemical structure on their high‐frequency dielectric performance and adhesive strength. This paper provides effective strategies for the structural design and preparation of high‐frequency, low‐dielectric composites, contributing to the further development of next‐generation microwave communication devices towards higher frequencies and faster information transmission. [ABSTRACT FROM AUTHOR]

Flexoelectricity, a universal electromechanical coupling effect present in all dielectric materials, has garnered significant theoretical and experimental interest in recent years, particularly in ferroelectric perovskite oxides. However, nitride-based materials have received considerably less attention. In this Letter, we report the observation of direct flexoelectric effect in plasma-enhanced chemical vapor deposition silicon nitride thin film with a thickness of 200 nm. From three-point bending tests, we determined the effective flexoelectric coefficient of Si3N4 to be 1.64 ± 0.22 nC / m. Additionally, the measured flexoelectric-induced voltages are consistent with finite element computational models. This observation of the flexoelectric coupling effect could contribute to the development of silicon nitride-based micro-scale devices. [ABSTRACT FROM AUTHOR]

This article is devoted to the development of a new method for the synthesis of magnetic cobalt boride nanoparticles using a low-energy approach. The obtained nanoparticles were used to create composite materials based on industrial thermoplastic ABS. The effect of different concentrations of nanoparticles on the physical, mechanical, magnetic, and dielectric properties of composite materials was studied. It was proven that by varying the concentration of nanoparticles in the ABS composite, it is possible to control the glass transition temperature from 107.5 to 112 °C. The resulting composites demonstrated superparamagnetic behavior, which changed linearly. The permittivity of the composite remained close to that of pure ABS, but a shift in the maximum permittivity to the low-frequency region was observed with an increase in the content of nanoparticles. Thus, a method for controlling the mechanical, magnetic, and dielectric properties of a composite material has been developed, which makes it possible to use routine ABS in a wider range of applications, including electrical devices. [ABSTRACT FROM AUTHOR]

Polymer-based composites are highly regarded as favorable candidate materials for dielectrics in high-energy-density capacitors, owing to their exceptional flexibility and fast charge-discharge capabilities. Recently, multilayer-structured polymer composites have gained significant attention as a promising solution for energy storage and dielectric applications, offering a combination of high energy density and low dielectric loss. These polymer multilayer films, comprising two or more layers synthesized through specific fabrication processes, have presented extensive uses in various applications, including packaging and optical materials, such as oxygen barrier, holographic anti-counterfeiting, and optical sensing, due to their versatile and tunable functionalities. The distinctive chemical composition and structural design of these layers, whether symmetrically or gradient distributed, endow these dielectric composites with superior integrated electric properties. This review provides a comprehensive overview of fabrication methods and strategies employed in the latest advancements in dielectric multilayer-structured polymers for energy storage applications. It delves into the design and manufacturing techniques of advanced multilayer composites, highlighting the diverse strategies utilized to enhance energy performance, such as polarization manipulation, electric field distribution control, interfacial modification, and geometric confinement of interfaces within both organic and organic/inorganic multilayer-structured composites. Lastly, this review addresses the current challenges and future prospects in the development of multilayer composites with enhanced energy storage performance. [ABSTRACT FROM AUTHOR]

Electrostatic capacitors with ultrahigh energy‐storage density are crucial for the miniaturization of pulsed power devices. A long‐standing challenge is developing dielectric materials that achieve ultrahigh recoverable energy density Wrec ≥ 10 J cm−3 under moderate electric fields (30 ≤ E ≤ 50 kV mm−1). Herein, a specific high‐entropy strategy is proposed to modulate the phase structure and interfacial polarization of medium‐entropy base materials using linear dielectrics. This strategy ensures a sufficient polar phase and a high enough electric field for complete polarization, thereby achieving ultrahigh Wrec by enhancing polarization strength. The validity of this strategy is demonstrated in the (Na0.282Bi0.282Ba0.036Sr0.28Nd0.08)TiO3‐xCa0.7Bi0.2TiO3 (NBBSNT‐xCBT) (x = 0–0.15) system. The CBT‐modulated samples exhibit a polyphase structure of R3c, P4bm, and Pm‐3m with reduced remnant polarization (Pr). Additionally, the addition of CBT effectively suppresses interfacial polarization, enhancing the maximum polarization (Pmax). These factors significantly improve the value of ∆P = Pmax − Pr. As a result, an ultrahigh Wrec of 10.5 J cm−3 with a high‐efficiency η of 80.3% is obtained in the x = 0.1 sample under a moderate electric field of 45 kV mm−1 for the first time. This work paves the way for achieving superior energy‐storage performance under moderate electric fields. [ABSTRACT FROM AUTHOR]

A multi-band high-sensitivity microwave sensor is reported. The two resonance units are based on complementary square spiral resonators (CSSRs) and produce four measurement bands through parasitic resonances. The four frequency bands are 2.001, 2.988, 5.438, and 7.755 GHz, respectively. Through an analysis of the coupling effects between the two CSSR resonance units, it is shown that the sensor is capable of simultaneously characterizing two samples with distinct dielectric properties. By adding a metal patch to the microstrip line, the overall quality factor of the sensor is enhanced, leading to higher sensitivity and accuracy in both real and imaginary part measurements. The measurement results demonstrate that this sensor provides an accurate and efficient solution for solid permittivity measurements. [ABSTRACT FROM AUTHOR]

Fracto-emission is the ejection of electrons and positive ions from matter undergoing a mechanical fracture. The creation and propagation of fractures in insulating material can generate an electrical signal that can be detected using a sufficiently fast signal recorder. The theoretical equations related to crack creation/propagation that induce an externally electric signal are detailed for two conditions: with and without an external applied electric voltage. Results from an experiment with no externally applied voltage are presented for fibreglass-reinforced epoxy laminate samples, in which current signals ranging from 50 mA to 100 mA are measured in a time frame of 200 ns. The signal-to-noise ratio is high enough to consider that the signal that was recorded is not a measurement artifact. This method may help to identify and track a crack propagating inside dielectric materials. [ABSTRACT FROM AUTHOR]

Nanosized materials are increasingly being recognized as inherent components in the development of energy storage devices and other state-of-the-art dielectric applications. In this work, nickel oxide (NiO), cobalt oxide (Co3O4) and NiO–Co3O4 nanocomposites in different compositions (10%, 20%, 30% and 40%) were successfully synthesized through hydrothermal method, optimizing concentrations of the precursors, and X-ray diffraction confirmed single-phase polycrystalline NiO and Co3O4. SEM images showed that distinct morphologies for each material and FTIR spectra reveal Ni–O and Co–O. UV–visible analysis shows a plasmon peak at 307 nm for NiO and excition absorption at 282 nm for Co3O4. NiO–Co3O4 nanocomposites displayed band gaps ranging from 2.37 eV to 2.67 eV. Dielectric properties showed a decrease in εʹ with frequency, attributed to Maxwell–Wagner and hopping models. AC conductivity increased with frequency due to Co3O4 content and oxygen vacancies. The study suggests potential applications in supercapacitors, spintronics, high-frequency devices and ultra-high dielectric materials. [ABSTRACT FROM AUTHOR]

Contact Electro‐Catalysis (CEC) using commercial dielectric materials in contact‐separation cycles with water can trigger interfacial electron transfer and induce the generation of reactive oxygen species (ROS). However, the inherent hydrophobicity of commercial dielectric materials limits the effective reaction sites, and the generated ROS inevitably undergo self‐combination to form hydrogen peroxide (H2O2). In typical CEC systems, H2O2 does not further decompose into ROS, leading to suboptimal reaction rates. Addressing the generation and activation of H2O2 is therefore crucial for advancing CEC. Here, we synthesized a catalyst by loading the dielectric material polytetrafluoroethylene (PTFE) onto ZSM‐5 (PTFE/ZSM‐5, PZ for short), achieving uniform dispersion of the catalyst in water for the first time. The introduction of an FeIII‐initiated self‐cycling Fenton system (SF‐CEC), with the synergistic effects of O2 activation and FeIII‐activated H2O2, further enhanced ROS generation. In the FeIII‐initiated SF‐CEC system, the synergistic effects of ROS and protonated azo dyes enabled nearly 99 % degradation of azo dyes within 10 minutes, a sixfold improvement compared to the CEC system. This represents the fastest degradation rate of methyl orange dye induced by ultrasound to date. Without extra oxidants, this system enabled stable dissolution of precious metals in weakly acidic solutions at room temperature, achieving 80 % gold dissolution within 2 hours, 2.5 times faster than similar CEC systems. This study also corrects the unfavorable perception of CEC applications under acidic conditions, providing new insights for the fields of dye degradation and precious metal recovery. [ABSTRACT FROM AUTHOR]