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Layered Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3 (NBT-6BT) ceramics of dense-porous-dense structure along the thickness are fabricated. The porous layer is sandwiched between the top and bottom dense layer, nullifying the electrode material's seepage into pores. Thus, porous pyroelectric material reduces the dielectric breakdown during poling and increases the repeatability of the poling process. The burnt-out polymer technique creates 10.7 %, 14.23 %, 21.3 % and 28 % porosity. The dielectric constant in layered porous structure decreased from 785 to 221 as the porosity increased from 5.4 % (pure NBT-6BT) to 28 % (layered NBT-6BT-12) at room temperature (poled condition). The introduction of porosity showed an increment of 124 % in the modified pyroelectric energy harvesting figure of merit F e * for NBT-6BT-12 at 80 °C. The real-time thermal energy harvesting obtained by heating and cooling the pyroelectric material demonstrated equivalent voltage for NBT-6BT-12 layered porous structure. The layered porous structure can be a viable alternative for enhanced voltage sensitivity and energy harvesting. • A layered porous structure of Na 0.5 Bi 0.5 TiO 3 -0.06BaTiO 3 (NBT-6BT) is fabricated for pyroelectric thermal energy harvesting. • The dielectric constant of the layered porous material decreases by 72 % compared to pure NBT-6BT, enhancing the voltage sensitivity. • Repeatability of the poling process is ensured in porous pyroelectric material using a dense-porous-dense structure. • The voltage sensitivity and modified energy harvesting capability of 28 % porous NBT-6BT increases by 192 % and 124 %. [ABSTRACT FROM AUTHOR]

As a dielectric material, BaTiO 3 -based ceramics are desirable for high performance ultra-thin multilayer ceramic capacitors (MLCCs) application. In this work, BaTiO 3 -based dielectric ceramics with superior dielectric properties were synthesized using a reducing atmosphere sintering process. It is found that the contribution of "wet" grain-boundary diffusion become significant as the oxygen partial pressure increases, resulting to a larger grain size and higher permittivity. Especially, for the specimen sintered in higher oxygen partial pressure, the stable temperature coefficient of capacitance (TCC) is dominated by irreversal domain due to the increase of super-lattice phase. Samples with higher oxygen partial pressure exhibit a higher permittivity of 2700 and better permittivity-temperature stability. Furthermore, ultra-thin MLCCs with thickness of 1 μm and capacitance of 10 μF and the TCC of X7R were successfully fabricated. This work provides a comprehensive explanation demonstrating upon the significant roles of grain size and defect engineering in the dielectric performance in BaTiO 3 -based ceramics, and points out an avenue to obtain excellent permittivity-temperature stability in ultra-thin MLCCs. [ABSTRACT FROM AUTHOR]

Moderate dielectric constant, low dielectric loss, and high dielectric tunability around or above Curie temperature are essential characteristics of dielectric tunable devices. Silver niobate (AgNbO 3), known for its antiferroelectric (AFE) and weak ferroelectric (FE) nature, offers a natural "composite" system combining AFE and FE attributes, making it an attractive candidate for tunable device materials. Microstructural modification through chemical methods can enhance its dielectric tunability. To this end, we propose and prepare a doped AgNbO 3 ceramic system, denoted as (1- x) AgNbO 3 - x LiTaO 3 (ANLT100 x , x ≤ 3.8 mol%). Structural analysis reveals that all samples maintain an average AFE-like polar structure. The introduction of dopants disrupts the ordered AFE-like structure, altering the proportion of AFE and FE states. This disruption leads to a notably improved relaxor dielectric response and an FE transition around room temperature. Consequently, we achieve a ceramic material (x = 3.8 %) with a moderate dielectric constant (ε r = 520) and low dielectric loss (tanδ = 0.008), accompanied by a hysteresis-free dielectric tunability (n r = 37.2 %) under an applied bias electric field of 40 kV cm−1, which is four times larger than that in AgNbO 3 (n r = 8 %) ceramic. These findings open new possibilities for developing dielectric tunable materials in device design. [ABSTRACT FROM AUTHOR]

Due to their responsiveness to modulation by external direct current fields, dielectric tunable materials are extensively utilized in integrated components, such as ferroelectric phase shifters. Barium strontium titanate ceramics have been considered the most potential tunable materials for a long time. However, the significant dielectric loss and high voltage drive have limited their further applications. Recently, Bi6Ti5WO22 ceramic has regained attention for its high dielectric tunability with low loss. In this study, we judiciously introduce Nb5+ with a larger ionic radius, replacing Ti4+ and W6+. This successful substitution enables the modulation of the phase transition temperature of Bi6Ti5WO22 ceramics to room temperature, resulting in superior tunable properties. Specifically, the 0.7Bi6Ti5WO22−0.3Bi6Ti4Nb2O22 ceramics exhibit giant tunability (~75.6%) with ultralow loss (<0.002) under a low electric field (1.5 kV/mm). This tunability is twice that of barium strontium titanate ceramics with a similar dielectric constant and only one-tenth of the loss. Neutron powder diffraction and transmission-electron-microscopy illustrate the nanodomains and micro-strains influenced by ion substitution. Density functional theory simulation calculations reveal the contribution of ion substitution to polarization. The research provides an ideal substitute for tunable material and a general strategy for adjusting phase transition temperature to improve dielectric properties. The authors realize composite optimization in dielectric tunable materials by simultaneously achieving low electric field, large tunability, and low loss through ion substitution design in ferroelectric tunable materials. [ABSTRACT FROM AUTHOR]

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When a dielectric material undergoes mechanical impact, it generates a shock wave, causing changes in its refractive index. Recent demonstrations have proven that the modified refractive index can be determined remotely using a millimeter-wave interferometer. However, these demonstrations are based on the resolution of an inverse electromagnetic problem, which assumes that the losses in the material are negligible. This restrictive assumption is overcome in this article, in which a new approach is proposed to solve the inverse electromagnetic problem in lossy and shocked dielectric materials. Our methodology combines a one-dimensional convolutional neural network architecture, namely Inverse problem of Lossless or Lossy Shocked Wavefront Network (ILSW-Net), with a nonlinear optimization technique based on the Nelder–Mead algorithm to estimate losses within dielectric materials under a mechanical impact. Experimental results for both simulated and real signals show that our method can successfully predict the velocities and the refractive index while accurately estimating the shock wavefront. [ABSTRACT FROM AUTHOR]

Increasing porosity is one of the most direct ways to improve the thermal insulation and dielectric properties of materials. Until now, many wet methods for preparing Si3N4 ceramic foams usually face the problems of complex rheology, long period, and expensive cost, and the reported pore sizes of Si3N4 ceramic foams are typically micron-grade, resulting in a lack of competitiveness in thermal insulation and wave-transparent applications. In this paper, the Si3N4@SiO2 ceramic foams were prepared using an efficient dry-method, which combined three processes of low temperature chemical vapor deposition (LTCVD), template, and isostatic pressing. The method has the advantages of simple operation and short preparation period, and can realize near-net size molding and mass production. In addition, the evolution mechanisms of honeycomb microstructure and composition of Si3N4@SiO2 ceramic foam during sintering were studied by chemical reaction thermodynamics. The as-prepared Si3N4@SiO2 ceramic foam possesses low density (0.377 g·cm−3), high compressive strength (7.5 MPa), low thermal conductivity (0.0808 W·m−1·K−1), and excellent dielectric properties (ε < 1.32, tan δ < 0.009) in the frequency range of 8–18 GHz, and its maximum working temperature in air can reach up to 1100 °C. It will be recommended to be applied in the interlayer of Si3N4 ceramic radome to improve its thermal insulation and electromagnetic wave transparency performances. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have unique advantages in harvesting low‐frequency irregular mechanical energy, and their output mainly depends on the surface charge density. Inhibiting the loss of triboelectric charges and optimizing the dielectric properties of materials are effective methods for boosting the surface charge density. Several optimization strategies for triboelectric layers, such as surface modification, insertion of intermediate layers, and optimization of dielectric properties, have been reported to improve the output performance of TENGs. In this perspective, first, the material optimization strategies for improving the output performance of TENGs are discussed. Then, in terms of output enhancement, the problems that need to be solved in the future are proposed. Finally, the future roads of high‐performance TENGs for truly realizing efficient mechanical‐energy harvesting are discussed. [ABSTRACT FROM AUTHOR]

Viruses can spread through contaminated aerosols and contaminated surface materials, and effective disinfection techniques are essential for virus inactivation. Nonthermal plasma‐generated reactive oxygen and nitrogen species can effectively inactivate the coronavirus. We aim to interpret the coronavirus inactivation level and mechanism of surface interaction with materials with and without dielectric barrier discharge (DBD) plasma treatment. Nonthermal plasma, particularly surface‐type DBD plasma, can inactivate human coronavirus 229E (HCoV‐229E) on porous (paper, wood, mask) and nonporous (plastic, stainless steel, glass, Cu) materials. Virus inactivation was analyzed using a 50% tissue culture infectivity dose (TCID50) using cell line, flow cytometry, and immunofluorescence. Surfaces contaminated with HCoV‐229E were treated at different time intervals (0–5 h) with and without plasma exposure (natural decay in ambient air conditions). HCoV‐229E persistence conformed to the following order: plastic > cover glass > stainless steel > mask > wood > paper > Cu with and without plasma exposure. HCoV‐229E was more stable in plastic, cover glass, and stainless steel in 5 h, and the viable virus titer gradually decreased from its initial log10 order of 6.892 to 1.72, 1.53, and 1.32 TCID50/mL, respectively, under plasma exposure. No virus was observed in Cu after treatment for 5 h. The use of airflow, ambient nitrogen, and argon did not promote virus inactivation. Flow cytometry and immunofluorescence analysis demonstrated a low expression level of spike protein (fluorescence intensity) during plasma treatment and in E and M genes expression compared with the virus control. [ABSTRACT FROM AUTHOR]

Deriving analytical expressions of dielectric permittivities is required for numerical and physical modeling of optical systems and the soar of non‐Hermitian photonics motivates their prolongation in the complex plane. Analytical models are based on the association of microscopic models to describe macroscopic effects. However, the question is to know whether the resulting Debye–Drude–Lorentz models are not too restrictive. Here, it is shown that the permittivity must be treated as a meromorphic transfer function that complies with the requirements of complex analysis. This function can be naturally expanded on a set of complex singularities. This singularity expansion of the dielectric permittivity allows to derive a generalized expression of the Debye–Drude–Lorentz model that complies with the requirements of complex analysis and the constraints of physical systems. It is shown that the complex singularities and other parameters of this generalized expression can be retrieved from experimental data acquired along the real frequency axis. The accuracy of this expression is assessed for a wide range of materials including metals, 2D materials and dielectrics, and it is shown how the distribution of the retrieved poles helps in characterizing the materials. [ABSTRACT FROM AUTHOR]

Currently, in the era of highly advanced information technology, dielectric materials exhibit extensive potential applications in the realms of energy storage and information transmission. Polypropylene stands as one of the most prevalent plastics, lauded for its exceptional mechanical, thermal, electrical, and processing attributes. This article expounds upon the intricate essence and energy storage principles underpinning dielectric materials while pinpointing the areas in which the current dielectric materials necessitate enhancements. It further delves into the study's selection of polypropylene as the base material, with a focus on the impact of individual fillers (ferroelectric ceramics, carbon materials, etc.) and mixed filler nanoparticles on augmenting the dielectric properties of polypropylene. We also delve into pertinent fabrication techniques and methodologies, such as the solution blending method, melt blending method, and in situ polymerization method. In the context of existing polypropylene‐based composite dielectric materials, this article introduces two quintessential applications: insulation materials for direct current cables and metal capacitor films. Finally, it concludes by summarizing the obstacles and challenges that high‐performance polypropylene‐based dielectric composites confront and offers insights into potential avenues for future research. [ABSTRACT FROM AUTHOR]

With 5G and millimeter-wave technologies evolving rapidly, the high communication frequency leads to high integration and miniaturization of the Luneburg lens (LL). In this paper, a miniaturized K-band flat LL with 0.95MgTiO 3 –0.05CaTiO 3 (95MCT) ceramic was designed and successfully printed by vat-photopolymerization 3D printing. Optimal 3D printing parameters and thermal treatment processes of 95MCT ceramic were investigated. The as-prepared 95MCT ceramic showed excellent properties: a density of 3.40 g/cm3, a high flexural strength of 81.78 MPa, a dielectric constant of 17.7, and a remarkably low dielectric loss value of 4.56 × 10-4. Based on the 95MCT ceramic, a flat LL with a diameter of 40 mm and thickness of 6 mm was printed with sophisticated metastructure. While miniaturization was accomplished with a high degree of dimensional compression, the printed flat LL showed a maximum gain enhancement over 5 dBi. Thus, this study provides a novel viewpoint on the fabrication of microwave dielectric ceramic and miniaturized ceramic radio frequency (RF) devices with complex structures. [ABSTRACT FROM AUTHOR]

Due to the prevalence of wearable electronic devices, Lead-free dielectric ceramics with excellent recoverable energy storage density and efficiency at low electric fields are well worth investigating. Moreover, maintaining excellent energy storage performance (ESP) in different environments is a huge challenge for researchers. In this study, 0.6Na 0·5 Bi 0·5 TiO 3 -0.4Sr 0·7 Bi 0·2 TiO 3 lead-free relaxor ferroelectric ceramics were modified by (Sr 0.7 Nd 0.2) (Ta 0·4 Ti 0.5)O 3 (BNST- x SNTT x = 0, 0.02, 0.04, 0.06). On one hand, BNT has a very high polarization strength, making it a very suitable basic element for designing high energy storage dielectric materials. On the other hand, Sr 0·7 Bi 0·2 TiO 3 and (Sr 0.7 Nd 0.2) (Ta 0·4 Ti 0.5)O 3 were introduced to improve the performance of ceramics, such as inducing polar nanoregions (PNRs), refining grain size, and increasing impedance. The results demonstrate that the energy storage characteristics of BNST- x SNTT were enhanced by introducing SNTT to the BNST. The ceramics exhibited a significant grain size reduction from 0.946 μm (x = 0) to 0.346 μm (x = 0.06). In addition, a great polarization difference (ΔP = 44.29 μC/cm2) was simultaneously achieved in the x = 0.02 sample. As a result, BNST-2SNTT (x = 0.02) ceramic obtained an excellent recoverable energy density of 3.24 J/cm3 and a satisfactory efficiency of 81.4 % at a low electric field of 190 kV/cm. Furthermore, the BNST-2SNTT ceramic exhibits excellent temperature stability (20°C–140 °C), frequency stability (1 Hz–500 Hz), and cycling reliability (10°-106 cycles). The corresponding fluctuation of ESP is less than 5 %. These properties indicate that the BNST-2SNTT ceramic is an excellent dielectric material for energy storage. [ABSTRACT FROM AUTHOR]

The spark-plasma sintering of ceramics based on the cubic pyrochlore phase in the system Bi2O3-ZnO-Nb2O5 is reported for the first time. It is shown that the use of spark-plasma sintering in the manufacture of (Bi1.5Zn0.5)2(Zn0.5Nb1.5)2O7 ceramics makes it possible to obtain a high density, a homogeneous microstructure, and high dielectric parameters (almost 30% higher compared to conventional ceramic technology). The paper discusses the features of microstructure formation and the optimization of spark plasma sintering regimes. [ABSTRACT FROM AUTHOR]

Since the integration of electronic devices and intelligent electronic devices into the power grid, power quality (PQ) has consistently remained a significant concern for system operators and experts. Maintaining high standards of power quality is crucial to preventing malfunctions and faults in electric assets and connected loads. Recently, PQ studies have shifted their focus to a specific frequency range, previously not considered problematic—the supraharmonic 2 kHz to 150 kHz range. This range is not populated by easily recognizable harmonic components of the 50 Hz to 60 Hz mains fundamental, but by a combination of intentional emissions, switching non-linearities and byproducts, and various types of resonances. This paper aims to provide a detailed analysis of the impact of supraharmonics (SHs) on power network operation and assets, focusing on the most relevant documented negative effects, namely power loss and the heating of grid elements, aging of dielectric materials, failure of medium voltage (MV) cable terminations, and interference with equipment and power line communication (PLC) technology in particular. Under some shareable assumptions, limits are derived and compared to existing ones for harmonic phenomena, providing a clear identification of the primary issues associated with supraharmonics and suggestions for the standardization process. Strictly related is the problem of grid monitoring and assessment of SH distortion, discussing the suitability of normative requirements for instrument transformers (ITs) with a specific focus on their accuracy. [ABSTRACT FROM AUTHOR]

Ferrimagnetic Mn0.25Co0.75Fe2O4 (MCF) nanoparticles were synthesized via sol–gel autocombustion method. Polyaniline (PANI) and PANI nanocomposites with MCF as filler (PANI/MCF) were synthesized through chemical oxidative in-situ polymerization of aniline under the presence of varying weight percentage of the MCF (10%, 20% and 50%). The MCF, PANI and PANI/MCF nanocomposites were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analyzer (TGA), field emission scanning electron microscopy equipped with elemental detection (FESEM-EDAX) and vibrating sample magnetometer. The XRD and FTIR spectra confirmed the formation of pure phase with high crystallinity for all the samples. TGA study showed the increased thermal stability of PANI with addition of MCF. MCF and PANI/MCF nanocomposites showed ferrimagnetic hysteresis loop under external magnetic field at room temperature. Additionally, the ac conductivity, dielectric and electrical properties as a function of frequency ranging from 100 Hz to 120 MHz, were investigated for all the samples using impedance analyzer at room temperature. Dielectric, TGA and magnetic studies showed that PANI/MCF with 50 weight percentage of MCF has maximum ac conductivity, thermal stability and moderate magnetic properties. Hence, it could be a potential candidate to be used as dielectric material in high frequency capacitors and for electromagnetic interference shielding material at high frequency. [ABSTRACT FROM AUTHOR]

Confining light at a subwavelength scale is important for building ultracompact opto-electronic networks. Plasmonic waveguides are good candidate devices for this purpose. However, the oscillation of electrons relating to surface plasmon polaritons causes energy dissipation, which limits the propagation length and thus reduces the waveguide performance. Here, we design a low-loss plasmonic waveguide composed of a nanowire dimer structure on a metal substrate, in which the dominant modes are localized within the air gap between the nanowires and referred to as air-host plasmonic modes. The use of air instead of dielectric materials as the host medium can reduce ohmic loss and avoid the dispersion effect of dielectric.When the constructed nanowires have a diameter less than 100 nm, the air-host mode has subwavelength-scale confinement and a propagation length of ~100 µm, which has broad application prospects for the construction of ultracompact plasmonic devices. [ABSTRACT FROM AUTHOR]

The flexoelectric effect, garnering extensive attention in recent years, is an electro-mechanical coupled gradient effect that widely exists in dielectric materials and holds great potential for applications in structural sensing and actuation. The parabolic shell structure, characterized by line focusing, finds widespread use in key structural components such as solar trough collectors and communication antennas. Distributed sensing of the structural states of these parabolic shells is critical for vibration control, health monitoring, and shape control of precision structural systems. Therefore, flexoelectric sensing research based on parabolic shell structure has become an important topic. This study establishes a mathematical model for flexoelectric sensing in a parabolic shell with four-sided simply supported boundary conditions. The model is based on the direct flexoelectric effect, and thin shell assumption, and incorporates specific Lamé parameters and curvature radius. The electro-mechanical strain gradient/signal generation characteristics and distributed modal flexoelectric signals on the parabolic shell are investigated. The sensing signal under the open-circuit conditions is deduced, and the flexoelectric sensing signal and sensing characteristics of different modes are analyzed. The formulation of the flexoelectric neural sensing signal for the parabolic shell structure is provided and divided into two components: a circumferential bending component and a longitudinal bending component. In the case studies, the effects of design parameters such as flexoelectric sensor thickness, size, and aspect ratios are evaluated and compared. The analysis and results of this study offer a theoretical foundation and reference for refining the design parameters of the flexoelectric sensor and determining its optimal sensing position, and potentially paving the way for new applications of flexoelectric sensing technology. [ABSTRACT FROM AUTHOR]

In order to meet the requirements of highly integrated and miniaturized electronic components, there is an urgent need for low dielectric materials with high mechanical properties and optical transparency in the field of microelectronics. In this study, a series of novel polyimide films (FPI) containing fluorenyl were prepared, and the effects of the fluorenyl content on the thermal, mechanical, and dielectric properties of the copolymerized films were investigated and discussed. The results demonstrate a significant decrease in the dielectric constant of the FPI films following the introduction of fluorenyl into polyimide (PI) chain segment. The FPI films also exhibited high mechanical properties, including tensile strengths between 92 and 106 MPa and elongation at break in the range of 8.4%–13.0%. Additionally, the introduction of the noncoplanar fluorenyl considerably improved the optical transparency and solubility of the FPI film. It is noteworthy that the FPI‐3 has the best dielectric properties, with a low dielectric constant of 2.61 at 10 MHz and shows low water absorption (0.49%). The results show that we have prepared a novel low dielectric PI material film with excellent mechanical properties and optical transparency by introducing fluorenyl into the PI chain segment. These FPI films with satisfactory properties may be good candidates for dielectric materials for electronic components. [ABSTRACT FROM AUTHOR]

In order to prepare polymer dielectric materials with high energy storage density, a series of polyimide (PI) based Janus composite films were prepared by metal–organic frameworks (MOFs) material (UiO‐66) with high dielectric constant (ɛr) and boron nitride nanosheets (BNNSs) with high breakdown strength (Eb). As reported, the UiO‐66 can significantly improve the ɛr of the composites. The ɛr of 20 wt% UiO‐66/PI film is 10.51 at 103 Hz, which is 3.1 times that of pure PI film (3.39 at 103 Hz). However, the Eb of 20 wt% UiO‐66/PI is only 58 MV m−1, which is only 16.51% of pure PI (352 MV m−1). The sharp decline in Eb reduces the energy storage capacity of the composites. To solve this problem, first, BNNSs with an average diameter of 2 μm and a thickness of 1.36 nm (about 4–5 layer) were obtained by hydrothermal reflux stripping. BNNSs/PI//UiO‐66/PI Janus composite films with double‐layer structure were prepared by directly casting BNNSs/PI on the surface of UiO‐66/PI. For 0.3 wt% BNNSs/PI//10 wt% UiO‐66/PI, the calculated energy storage density (Ue) is 5.75 J cm−3 at 140 MV m−1, which is 3.57 times that of pure PI film (1.61 J cm−3 at 140 MV m−1). Meanwhile, the charge discharge efficiency is 82.55% (at 140 MV m−1). Highlights: BNNSs prepared by hydrothermal reflux stripping have fewer layers.BNNSs/PI composites improve the Eb of UiO‐66/PI composites by Janus structure.The Ue of BP‐0.3//UP‐10 composites with Janus structure was 5.75 J cm−3. [ABSTRACT FROM AUTHOR]

Among a wide variety of polymer-based dielectric materials, aromatic polyimide (PI) and its derivatives have garnered significant attention as gate dielectrics for use in organic thin-film transistors (OTFTs) due to their flexibility, large-area processability, high-temperature resistance, and cost-effectiveness. In this work, we utilized a structure fine-tuning manner by incorporating different amounts of methyl groups into the PI backbone. Two solution-processable aromatic PI-derived materials were prepared using the low-temperature chemical imidization method, and they displayed good film-forming properties, excellent thermal stability, low leakage current density, and low dielectric loss, providing a solid foundation for their use as OTFT gate dielectric layers. As a proof of concept, we utilized these two PI-derived dielectric layers for application in para-sexiphenyl (p-6P)/vanadyl-phthalocyanine (VOPc) TFT devices. Compared to the pristine PI without methyl groups, the mobility and threshold voltage of the OTFT based on PI containing different amounts of methyl groups as dielectric layers have been significantly improved. The strategy of methyl functionalization on PI side chains reported in this work may offer new possibilities for achieving high mobility and low threshold voltage in OTFTs. [ABSTRACT FROM AUTHOR]

A series of poly(ester imide) (PEsI) copolymers were synthesized using 3,3',4,4'-biphenyltetracarboxylic dianhydride (4,4'-BPDA), 2,2'-bis(trifluoromethyl) benzidine (TFMB), and 4-aminophenyl-4'-aminobenzoate (APAB) as the monomers. Wide-angle x-ray diffraction results revealed that the average interchain distances of these polymers ranged from 4.6 to 5.7 Å, increasing with the increase of TFMB contents. PEsI-0.3 and PEsI-0.4 exhibited a glass transition temperature (Tg) of 445 and 455°C, respectively, while no distinctive Tg was observed for the PEsI copolymers when the APAB content was >50 mol%. The coefficients of thermal expansion (CTE) of these PEsI copolymers ranged from 3.8 to 24.2 ppm K-1, increasing with the increase of TFMB contents. The PEsI copolymers exhibited a modulus of 5.7-7.8 GPa, a tensile strength of 282-332 MPa, and an elongation-at-break of 10.2%-23.3%. Furthermore, these copolymers exhibited a dielectric constant of 2.53-2.76, and a low dissipation factor (Df) of 0.0026-0.0032 at 10 GHz in dry state. Because of their excellent combined properties, these PEsI copolymers are promising candidates as dielectric substrate materials for the applications in next generation flexible printed circuit boards operating at high frequencies. [ABSTRACT FROM AUTHOR]

We consider superconducting single-photon detectors, which are the key element of quantum optical technologies due to their unique characteristics not available in other technologies today. Since the first demonstration in Russia in 2001, such detectors have evolved significantly, and their waveguide-based versions are ready for scaling both in the fields of classical technologies (attenuated light) and of quantum optical applications (non-classical light). The paper studies the operating principle of such detectors and their main characteristics, analyzes superconducting materials and dielectric waveguide platforms, highlights the design principles, considers various levels of integration of on-chip waveguide superconductor detectors, and presents important new areas of application towards the implementation of photonic and ion quantum processors, as well as energy-efficient neuromorphic computing. [ABSTRACT FROM AUTHOR]

Electric Discharge Machining (EDM) is a prominent technique for producing components with complex geometry and intricate shapes. However, productivity depends on the selection of optimal input variables. This research investigates EDM and Near-Dry EDM (NDEDM) on AA7050 hybrid composites, exploring the impact of tool materials, Al2O3 powder concentration, and dielectric fluids on Material Removal Rate (MRR) and Surface Roughness (Ra). NDEDM offers a higher MRR due to localized heating and energy concentration, while hydrocarbon oil EDM provides lower Ra due to cooling and lubrication. Tool material properties, thermal conductivity and bonding strength, affect MRR and TWR. Aluminum composite tools via stir casting display a strong bonding interface, leading to efficient energy transfer and higher MRR, while copper composite tools via friction stir processing exhibit weaker bonding, potentially reducing MRR. Hydrocarbon oil significantly lowers TWR due to effective lubrication and cooling, while near dry EDM results in slightly higher TWR. Al2O3 powder enhances MRR, with an optimal concentration of 1 g/l, while higher concentrations hinder MRR. The presence of Al2O3 powder enhanced the surface quality by reducing the size of the recast layers and producing a smoother surface. Globules, craters, microcracks, pock marks and re-casted layers are the noticeable features spotted on the surface. The results were optimized using the TOPSIS optimization technique and process parameters 32 A current, 30 µs Ton, 3 mm gap distance machined under 3 g/l Al2O3 incorporated hydrocarbon oil dielectric medium using copper composites tool proffers optimal machining performance. [ABSTRACT FROM AUTHOR]

Metamaterial-based designs in ultra-high field (≥7 T) MRI have the promise of increasing the local magnetic resonance imaging (MRI) signal and potentially even the global efficiency of both the radiofrequency (RF) transmit and receive resonators. A recently proposed metamaterial-like structure—comprised of a high-permittivity dielectric material and a set of evenly distributed copper strips—indeed resulted in a local increase in RF transmission. Here, we demonstrate that non-uniform designs of this metamaterial-like structure can be used to boost the ultimate RF field distribution. A non-uniform dielectric distribution can yield longer electric dipoles, thus extending the RF transmit field coverage. A non-uniform distribution of conducting strips enables the tailoring of the local electric field hot spots, where a concave distribution resulted in lower power deposition. Simulations of the brain and calf regions using our new metamaterial-like design, which combines non-uniform distributions of both the dielectric and conducting strips, revealed a 1.4-fold increase in the RF field coverage compared to the uniform distribution, and a 1.5–2-fold increase in the transmit efficiency compared to the standard surface-coil. [ABSTRACT FROM AUTHOR]

Dielectric elastomers have attracted considerable attention both from academia and industry alike over the last two decades due to their superior mechanical properties. In parallel, research on the mechanical properties of dielectrics has been steadily advancing, including the theoretical, experimental, and numerical aspects. It has been recognized that the electromechanical coupling property of dielectric materials can be utilized to drive deformations in functional devices in a more controllable and intelligent manner. This paper reviews recent advances in the theory of dielectrics, with specific attention focused on the theory proposed by Dorfmann and Ogden. Additionally, we provide examples illustrating the application of this theory to analyze the electromechanical deformations and the associated bifurcations in soft dielectrics. We compared the bifurcations in elastic and dielectric materials and found that only compressive bifurcation modes exist in elastic structures, whereas both compressive and tensile modes coexist in dielectric structures. We summarize two proposed ways to suppress and prevent the tensile bifurcations in dielectric materials. We hope that this literature survey will foster further advancements in the field of the electroelastic theory of soft dielectrics. [ABSTRACT FROM AUTHOR]

Low-k dielectric materials were prepared by sintering ZSM-5 zeolite powder compacts at temperatures ranged 1200-1300°C, and the microwave dielectric characteristics were investigated together with the structure evolution during sintering. It was failed to obtain ZSM-5 ceramics by high temperature sintering because the densification could never occur below the tolerable temperature and the ordered porous structure completely collapsed above the tolerable temperature. The structure changed from ZSM-5 zeolite to SiO2-Al2O3 glass at 1240°C, and finally to SiO2-based cristobalite ceramics above 1275°C.Alow dielectric constant (2.63-2.78) combined with low dielectric loss (< 0.0005 at 18GHz) and small temperature coefficient of resonant frequency (varied from -18.6 to -8.1 ppm/°C) was achieved in the present materials, and the value of dielectric loss was the lowest one achieved so far in the dielectric materials with a dielectric constant lower than 3. With the structure evolution fromZSM-5 zeolite to SiO2-Al2O3 glass and finally to SiO2-based cristobalite ceramics, the dielectric constant increased from 2.27 to 2.78, while the Qf value indicated a complicated variation tendency, and the higher Qf values were achieved in the amorphous and crystalline states, while significant drop was determined in the partial amorphous state. It should be a great challenge to prepare dense zeolite ceramicswithout collapse of ordered porous structure, and then the ultra-low dielectric constant materials with high Q could be expected. [ABSTRACT FROM AUTHOR]

This contribution discusses the impact of sintering temperatures on dielectric properties of 3D-printed alumina (Al2O3) in the W-band, by evaluating high quality factor (-Q) resonators integrated in a 2D photonic crystal structure. By varying the sintering temperature of the lithography-based ceramic manufactured (LCM) samples, the microstructure of the material can be defined, which has a direct impact on the dielectric permittivity and material losses. Using a highly accurate photonic crystal structure, with a dimensional variation below 2% from print to print, an accurate extraction and evaluation of the dielectric material properties could be achieved. The relative permittivity of the alumina was tuned from 4.4 at 1250°C to 9.2 at 1650°C, whereas the observed change in dielectric losseswas moderate. Themaximum in observed dielectric loss for samples sintered at the lowest evaluated temperature, only yields an average value of 30 x 10-4. This demonstrates the versatility of the LCMtechnology for mm- and sub-mm-wave applications and its possibilities for material tuneability. [ABSTRACT FROM AUTHOR]

This research article examines the effects of atomic ordering on the structural and ferroelectric properties of (Ba, Sr) TiO3 solid solutions. Using density functional theory and molecular dynamics simulations, the study investigates how the concentration and ordering of Sr atoms influence local polarization, phase stability, and field-induced switching. The results demonstrate that atomic ordering impacts the Curie temperature, polarization, and stability of ferroelectric phases. This study contributes to our understanding of how atomic ordering affects material properties and offers insights into optimizing ferroelectric phases and functional properties in nanostructures. The document also provides additional information, references, and access to supporting data for further exploration. [Extracted from the article]

Polyureas have been widely applied in many fields, such as coatings, fibers, foams and dielectric materials. Traditionally, polyureas are prepared from isocyanates, which are highly toxic and harmful to humans and the environment. Synthesis of polyureas via non-isocyanate routes is green, environmentally friendly and sustainable. However, the application of non-isocyanate polyureas is quite restrained due to their brittleness as the result of the lack of a soft segment in their molecular blocks. To address this issue, we have prepared polyester polyureas via an isocyanate-free route and introduced polyester-based soft segments to improve their toughness and endow high impact resistance to the polyureas. In this paper, the soft segments of polyureas were synthesized by the esterification and polycondensation of dodecanedioic acid and 1,4-butanediol. Hard segments of polyureas were synthesized by melt polycondensation of urea and 1,10-diaminodecane without a catalyst or high pressure. A series of polyester polyureas were synthesized by the polycondensation of the soft and hard segments. These synthesized polyester-type polyureas exhibit excellent mechanical and thermal properties. Therefore, they have high potential to substitute traditional polyureas. [ABSTRACT FROM AUTHOR]

Lithium fluoride (LiF) is currently a very popular dielectric material used as a passivation or transport layer in a variety of applications, especially in high-efficiency solar cells. Despite this, its conduction properties and interface behavior with silicon remain largely unexplored. In this work, a LiF metal–insulator–semiconductor (MIS) structure is fabricated and characterized, and its properties are compared to the well-understood aluminum oxide (Al2O3) MIS structure. First, a higher current density in LiF compared to Al2O3 is highlighted, as well as its PN junction-like behavior with n-type silicon (n-Si), being rather unconventional for a dielectric layer. C–V measurements showcase the likely presence of an interface defect, causing an increase in the apparent doping and a shift in the flatband voltage VFB by +70 meV. This defect is found to be of the acceptor type, which renders the interface fixed charge more negative and improves the field-effect passivation in the case of a negative Qf. Finally, a density of interface states D i t ≈ 2 × 10 11 cm − 2 eV − 1 was found for LiF/n-Si, which is a low value showing appropriate chemical passivation at the interface. Overall, this work enables us to shed more light on the interface properties of LiF on n-Si, which is an essential step toward its wider use in state-of-the-art solar cells and other silicon-based devices. [ABSTRACT FROM AUTHOR]

The graphene-based plasmonic antenna's operating frequency and performance are significantly controlled by the substrate dielectric material. In this article, a plasmonic microstrip antenna is designed and simulated for terahertz applications. The design procedure is performed by testing different dielectric substrate materials of the same thickness, such as RT5800, polyimide, quartz, silicon dioxide (SiO2), FR4, mica, silicon nitride (SiO3N4), and gallium arsenide (GaAs). Generally, the computed results reveal that the quartz substrate maintains suitable radiation performance with a minimum S11 values of − 45.67 dB, efficiency of 92.65%, gain of about 3.15 dB, and bandwidth values of 310 GHz. Furthermore, a modification is done in the antenna by increasing the substrate height to obtain tri-band radiation mode. The results indicate that the proposed antenna operates at tri-band frequencies when the substrate thickness is larger than 6 µm. However, a better antenna radiation performance is observed with a substrate thickness of 7 µm which operates at frequencies of 0.766, 3.285, and 4.510 THz. Additionally, the overall radiation performance obtained for the proposed antennas of a single band frequency with quartz and dual and triple band frequencies with GaAs is compared with previous study results done by other researchers and a reliable agreement with an advancement in present work, especially in terms of antenna size and bandwidth. Finally, it can be said that the implementation of a graphene patch conductor to develop milt-band resonance frequency is an easy technique with low profiles, simple and alternative to the implementing conducting material slots, or extensions along the patch radiating borders techniques. [ABSTRACT FROM AUTHOR]

This research presents the design and analysis of a compact MIMO antenna tailored for 5G millimeter-wave applications, specifically targeting bands N257, N260, and N262. The antenna, characterized by its straightforward design, maintains compact dimensions of 10 mm × 16 mm while delivering exceptional performance with high gain. Employing Rogers RT/Duroid 5880 substrate material with a thickness of 0.508 mm, the antenna consists of two crescent-shaped radiating elements (patches) situated on the top surface of the dielectric material, complemented by a slotted ground on the bottom. The radiating elements are fed through a 50-Ω microstrip line. Operating across three distinct bands, the antenna's capabilities are outlined as follows: the first band spans from 27.2 to 29 GHz, centering around 28 GHz; the second band encompasses the frequency range from 34 to 40.2 GHz, with a center frequency of 39 GHz achieved through slotting crescent-shaped radiating elements; the third band, ranging from 47.5 to 51.3 GHz with a center frequency of 48.7 GHz, is attained by engraving circular slots on the ground. To validate simulation outcomes, a hardware prototype of the antenna is manufactured, showcasing excellent agreement between simulations and measurements. The antenna design is implemented using the CST Microwave Studio software tool and is benchmarked against existing literature. Key attributes of the proposed antenna include its compact size, simple geometry, wide bandwidth, and high gain. The antenna's favorable MIMO parameters (ECC, TARC, DG, and CCL), coupled with minimal spacing between elements, position it as a promising candidate for forthcoming 5G millimeter-wave communication applications. [ABSTRACT FROM AUTHOR]

A kind of all‐dielectric circularly polarised (CP) loop antenna made of high‐permittivity material is proposed. The leaky‐wave radiation from a high‐permittivity dielectric waveguide is utilised here to support the operation of the proposed antenna. A non‐closed dielectric loop covering a three‐quarter circle is adopted to generate CP radiation and it is connected with the dielectric ground via one of bending ends to form an all‐in‐one structure of the antenna. The other end is also bent and vertical to the ground, but hanging in the air for probe feed. As two kinds of typical high‐permittivity dielectric materials, zirconia ceramic and pure water are used to implement the proposed design respectively. On one hand, an all‐ceramic CP loop antenna made of zirconia is proposed. And benefiting from the low loss and high melting point of zirconia, the proposed ceramic antenna has superiority in radiation efficiency and could adapt to a harsh environment. On the other hand, by using pure water and transparent container, a fully‐transparent CP water loop antenna can be obtained. Finally, a 3‐D printing technology is adopted in the manufacturing of ceramic structure and resin container. Measured results of both antennas demonstrate the validity of the proposed design. [ABSTRACT FROM AUTHOR]

In this work we studied the effects which occur during the incidence of p-polarized electromagnetic wave on the solid-state structure "coating-uniaxial plasmonic metasurface-dielectric-metal". The purpose of this work is researching how the coating influences the effect of reflectionless incidence of the p-polarized electromagnetic waves on the solid-state structure "uniaxial plasmonic metasurfacedielectric-metal". Numerical modelling was used to find the conditions that lead to reflectionless incidence of the p-polarized electromagnetic wave on the solid-state structure under consideration. Using this method we determined the parameters of the coating which are required to observe incidence of p-polarized waves with no reflection. It was found that dielectric coating of the solid state structure significantly changes the behavior of the effect. We showed that dielectric permittivity of the coating changes the frequencies at which reflectionless p-polarized waves occur. The dependency was established between permittivity and thickness of the coating which causes the effect of the reflectionless incidence of p-polarized waves. The conducted research has a great scientific and practical interest. The solid-state structure that was studied can be applied for designing conceptually new types of nanoelectronic and optical devices. [ABSTRACT FROM AUTHOR]

The development of the digital society has led to an urgent demand for high-temperature-resistant, low-dielectric cable insulation materials. In order to meet the stable high temperature service performance, it is necessary to use inorganic materials instead of the traditional organic insulating materials as the cable insulation layer. Silicon dioxide (SiO 2) as a widely used inorganic dielectric material has great potential for application, and quartz fiber is another wave-transparent material with good dielectric properties. The combination of SiO 2 and quartz fiber can provide a feasible path for pure inorganic composite insulation materials. In this work, the high-throughput (>50 g) synthesis of SiO 2 was investigated to explore the factors affecting the dielectric properties. The effects of different quartz fiber composite amounts and sintering temperatures on the dielectric properties of the composites were investigated by testing the dielectric properties of the composite powders after pressing. The composite powders doped with 20 wt% quartz fibers at 600 °C sintering temperature were found to have better dielectric properties with dielectric constant of 2.48 and dielectric loss of 0.0109 at 20 M Hz. Furthermore, the composite powders were filled into the cables and measured for electrical properties by a network analyzer. And dielectric properties of the cables preliminarily meet the performance requirements for the applications of high temperature (900 °C) radio frequency (RF) communication cables with dielectric constant of 1.731 and insertion loss of 2.02 dB at 18 G Hz. Therefore, this inorganic composite material can be used as the insulation layer for RF high-temperature-resistant communication cables for aerospace, nuclear power plants and energy fields. [ABSTRACT FROM AUTHOR]

This paper presents a novel circular fractal ring monopole antenna for ultra‐wideband (UWB) hardware with dual band‐notched properties. The proposed antenna consists of four crescent‐shaped nested rings, a tapered feeding line at the front of the dielectric material, and a semicircular ground plane on the backside. In this design, the nested rings are used both as a radiation element and a band rejection element. The proposed antenna has a bandwidth of 9.03 GHz, which works efficiently in the range of 2.63 GHz–11.66 GHz with the dual notched bands of Worldwide Interoperability for Microwave Access (WiMAX) at 3.15 GHz–3.66 GHz and wireless local area network (WLAN) at 4.9 GHz–5.9 GHz, respectively. The antenna has a compact size of 20 mm × 30 mm × 1 mm (0.177 × 0.265 × 0.0084 λ0) and is implemented using a flame‐retardant type 4 (FR4) material. It has a maximum gain of approximately 4 dB in its operating range, and experimental results support the simulation predictions with high accuracy. The findings of this study imply that the designed antenna can be utilized in UWB applications. [ABSTRACT FROM AUTHOR]

Insulation materials with low dielectric constants, low coefficients of thermal expansion (CTE), low densities, renewability, and low cost are urgently needed in the fields of communication, control and signal cables. Here we report that combining cyclic olefin copolymer (COC) with linear low‐density polyethylene (LLDPE) by melt blending achieves the above goals. The dielectric constant and CTE of LLDPE/COC blends are minimized at 20 wt% COC content, reaching a value of 2.23 at 1000 Hz and 1.21 × 10−4 K−1, respectively. The density of the blend increases by only 1.6% compared with LLDPE, whereas the tensile modulus increases by 56%, which is conducive to the blends to improve mechanical strength while preserving lightweight. The rheological tests show that the zero‐shear viscosity, storage modulus, and loss modulus of the LLDPE/COC blends do not change much compared with pristine LLDPE, maintaining their good melt processability at 160°C. The cyclic rigid structure of COC causes a decrease in CTE, and the increase in free volume between molecular chains is responsible for the reduced dielectric constant. The present work provides a promising route to the design and fabrication of melt‐reprocessable polymer composites with low dielectric constant and low thermal expansion. [ABSTRACT FROM AUTHOR]

Plasma technology has undeniably revolutionized industrial processes in recent decades. Atmospheric pressure plasma (APP) has emerged as a prominent and widely applicable tool in various scientific disciplines. Notably, plasma-assisted flow control has become a subject of intense interest, particularly applying surface dielectric barrier discharge (SDBD) plasma actuators for aerodynamic flow control. In this study, a two-dimensional model of the SDBD plasma actuator is developed using the COMSOL Multiphysics program, incorporating air gas discharge reactions with N2/O2/Ar gases in specific ratios (0.78, 0.21, 0.01). The investigation focuses on the impact of dielectric materials (mica, silica glass, quartz, and polytetrafluoroethylene (PTFE)) on plasma characteristics and body force within the plasma actuator under constant input parameters. Moreover, the study explores how variable pressure (760, 660, and 560 torr) in different applications influences plasma properties, ultimately affecting the magnitude of the body force in the plasma actuator. These findings contribute to optimizing plasma technology for flow control applications and enhance industrial efficiency and performance. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of International Journal of Engineering Transactions B: Applications is the property of International Journal of Engineering (IJE) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Retroreflective gratings serve as fundamental optical elements in nanophotonics, with polarization-independent diffraction efficiency being one of the critical parameters for assessing their performance. In the far-infrared spectral range, traditional retroreflective gratings typically refer to metal echelette gratings, but their diffraction efficiency cannot approach 100% due to metal absorption. In the visible and near-infrared spectral ranges, metal echelette gratings have gradually been replaced by all-dielectric metasurfaces because dielectric materials exhibit negligible absorption at specific wavelengths. However, there is still a lack of relevant research in the far-infrared range, mainly due to the weak control capability of the existing devices over the polarization-independent phase. Here, we propose a kind of all-dielectric retroreflective metasurface composed of asymmetric pillars and freely tunable aperiodic multilayer films. The pillar structure can achieve polarization insensitivity, and the insufficient modulation capability of the dielectric materials can be compensated for by aperiodic Ge/ZnS films. The designed metasurface achieves the diffraction efficiency by RCWA, with the maximum larger than 99% and the overall reaching 95% (9.3–9.6 µm). We have provided detailed explanations of the design methodology and fabrication process. Our work lays the groundwork for further exploration and application of far-infrared lasers. [ABSTRACT FROM AUTHOR]

Multilayer ceramic capacitors (MLCCs) prepared using Ba1−xSrxTiO3 (BST) ceramics exhibit high dielectric constants (~1000), low dielectric loss (<0.01), and high breakdown voltage, with particularly significant tunability in dielectric properties (>50%) and with poor temperature stability. Doping-dominated temperature stability improvements often result in unintended loss of dielectric properties. A non-doping method has been proposed to enhance the temperature stability of BST capacitors. The composite gradient multilayer (CGML) ceramic capacitors with BaxSr1−xTiO3, where 0.5 < x < 0.8, as the dielectric, were prepared using a tape-casting method and sintered at 1250 °C. There exists a dense microstructure and continuous interface between the BaxSr1−xTiO3 thick film and the Pt electrodes. CGML ceramic capacitors feature a high dielectric constant at 1270, a low dielectric loss of less than 0.007, and excellent frequency and temperature stability. The capacitor showcases remarkable dielectric properties with a substantial tunability of 68% at 100 kV/cm, along with a notably consistent tunability ranging from 20% to 28% at 15 kV/cm across temperatures spanning from 30 to 100 °C, outperforming single-component BST-MLCCs in dielectric performance. [ABSTRACT FROM AUTHOR]

In the electric discharge machining process, the material is separated from the surface of the work piece by an electric spark, and in the presence of the dielectric material and tool electrode, changes are made on the surface of the work piece. In this project, we investigated the effect of dielectric material and brass tool electrode diffusion on the surface of carbon steel workpiece by means of quantmetric analysis, X-ray diffraction and electrochemical impedance spectroscopy. The effect of the parameters such as electric current intensity (I), pulse on time (ton), pulse off time (toff) and machining time (τ) on the composition of work peace, microstructure and electrochemical corrosion of machined work peace, were investigated. The results of quantmetric analysis showed that with the increase of machining parameters, the amount of diffused copper (from brass tool electrode) and carbon (from pyrolysis of flashing dielectric material) on the surface of machined carbon steel was increased. X-ray diffraction results confirmed that the formation of different phases such as Fe1.92C0.08, Cu4, Cu2 and Fe2 on the surface of workpiece, which was accordance with the quantmetric results. Electrochemical studies showed that during the EDM process, the electrochemical corrosion resistance was increased. [ABSTRACT FROM AUTHOR]

The paper deals with the capacitance of cylindrical two-dimensional capacitor which consists of Cartesian orthotropic dielectric material. The determination of the capacitance of capacitor with orthotropic dielectric material by a suitable coordinate transformation is reduced to the computation of capacitance of an isotropic capacitor. It is proven that the capacitance of a Cartesian orthotropic capacitor can be obtained in terms of an isotropic capacitor whose dielectric constant is the geometric mean of the dielectric constant of the orthotropic capacitor. [ABSTRACT FROM AUTHOR]

Achieving renewable power for self‐powered electronic devices such as micro/nano‐electro‐mechanical systems is attractive in the fields of energy resources and environment, in this regard, dielectric material structures with excellent energy storage and electromechanical responses have stimulated a surge of research interest. However, in the micro/nanoscale filed, the existing thermo‐electromechanical continuum theories are not capable of fully and effectively characterizing the arising effects, for example, size‐dependent effect and heat lagging effect, etc. To further develop the existing theories, a theoretical prototype for piezo‐flexoelectricity by incorporating strain gradient effect and dual‐phase‐lag heat conduction model is proposed for the first time in this study, and then this proposed model is applied to investigating the energy harvesting performances of a piezo‐flexoelectric micro‐beam under piezoelectric‐thermoelastic coupling. In terms of the differential form of two‐phase elasticity and Hamilton's principle, the governing equations and the boundary conditions for the transverse vibration of a micro‐beam based on the Euler–Bernoulli beam model are derived. By means of the assumed mode method, the influences of the flexoelectricity, the load resistance and the strain gradient on voltage and output power are examined. From the obtained results, it can be aware of that this study not only presents the piezoelectric‐thermoelastic coupling effect of piezo‐flexoelectric configuration in microscale field, but also presents that a piezo‐flexoelectric system at microscale can generate higher power than that reported in previous works. It is hoped that this study could provide some guidelines in designing and optimizing dielectric energy harvesters of micro/nano electronic devices. [ABSTRACT FROM AUTHOR]

Ground penetrating radar (GPR) is a commonly used tool for railway trackbed inspection due to its ability to collect information about subsurface materials at high resolution and high speed. Although GPR recording systems allow for the collection of vast quantities of data (hundreds of kilometres per day), accurate ground truth information is difficult to obtain. Models of trackbed can be used to generate synthetic radargrams to provide a better understanding and predictability of GPR responses to a wide range of trackbed conditions. In this research, we produced models of ballast using randomly shaped 3D particles, with a range of particle size distributions to represent various stages of ballast breakdown. Additionally, void spaces are partially filled with a constant dielectric material to represent ballast contamination. We used gprMax to simulate the GPR response for a 2 GHz horn antenna over the trackbed models. These simulations resulted in radargrams that are visually indistinct from real recorded data in known conditions. These radargrams, along with their formative models, have provided valuable insights into how variations in trackbed conditions can impact GPR data. [ABSTRACT FROM AUTHOR]

This research article examines the effects of atomic ordering on the structural and ferroelectric properties of (Ba, Sr) TiO3 solid solutions. Using density functional theory and molecular dynamics simulations, the study investigates how the concentration and ordering of Sr atoms influence local polarization, phase stability, and field-induced switching. The results demonstrate that atomic ordering impacts the Curie temperature, polarization, and stability of ferroelectric phases. This study contributes to our understanding of how atomic ordering affects material properties and offers insights into optimizing ferroelectric phases and functional properties in nanostructures. The document also provides additional information, references, and access to supporting data for further exploration. [Extracted from the article]

In this work, Co0.5Zn0.5LaxFe2-xO4 (0.00 ≤ x ≤ 0.10) spinel ferrites were synthesized using the sol-gel auto-combustion method. X-ray diffraction (XRD) analysis and Rietveld refinement confirmed the presence of a cubic spinel structure. The crystallite size was estimated to be between 17.5 nm and 26.5 nm using Scherrer’s method and 31.27 nm–54.52 nm using the Williamson–Hall (W-H) method. Lattice constants determined from XRD and Rietveld refinement ranged from (8.440 to 8.433 Å and 8.442 to 8.431 Å), respectively. Scanning electron microscopy (SEM) revealed a non-uniform distribution of morphology with a decrease in particle size. The bandgap values decreased from 2.0 eV to 1.68 eV with increasing rare earth (La3+) doping concentration. Fourier-transform infrared (FT-IR) spectroscopy confirmed the presence of functional groups and M-O vibrations. The dielectric constant and dielectric loss exhibited similar behavior across all samples. The maximum tan δ value obtained at lower frequencies. Regarding magnetic behavior, there was a decrease in magnetization from 55.84 emu/g to 22.08 emu/g and an increase in coercivity from 25.63 Oe to 33.88 Oe with higher doping concentrations. Based on these results, these materials exhibit promising properties for applications in microwave and energy storage devices.