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In this paper, the strategy of substituting Ti4+ for Nb5+ in Mg4Nb2O9 microwave dielectric ceramic was employed to improve the microwave dielectric properties. Specifically, a maximum Q × f value of 137,462 GHz was obtained at x = 0.15, resulting in a nearly 30% increase in the quality factor (Q × f) for the Mg4Nb2−xTixO9−x/2 sample. Moreover, we investigated the phase composition, micromorphology, and the relationship between structural characterization and dielectric properties. The X-ray diffraction (XRD) patterns indicated that only a single Mg4Nb2O9 phase with a trigonal corundum-type structure was formed in all the samples. The ɛr was related to the ionic polarizability, and the τf value was dependent on the B–O bond valence (VB–O) and BO6 octahedral distortions. Ultimately, the Mg4Nb1.85Ti0.15O8.925 ceramic sample exhibited microwave dielectric properties with ɛr = 13.89, Q × f = 137,462 GHz, and τf = − 55.1 ppm/°C. [ABSTRACT FROM AUTHOR]

Microwave dielectric ceramics are essential for producing microwave components, seriously affecting the development and application of wireless communication technology. In this paper, Zn1.8-xMnxSiO3.8 (0 ≤ x ≤ 0.20) ceramics were prepared by solid-phase reaction method. The sintering characteristics, phase compositions, microstructures, and dielectric properties of the materials were investigated. The addition of Mn2+ ions lowered the sintering temperature of the ceramics, and the densification temperature decreased from 1300 to 1200 ℃ as the amount of Mn2+ substitution increased. The Mn2+ substitution (x = 0–0.2) effectively formed a Zn2SiO4 solid solution without the appearance of any other secondary phases. A moderate amount of Mn2+ improves the microscopic morphology of Zn1.8-xMnxSiO3.8 ceramics and enhances their Q × f. The theoretical and relative densities of the material were maximized at x = 0.04, where the ρbulk = 4.0865 g/cm3 and ρrela = 97.7%. At x > 0.12, the grain size grows, and anomalous grains appear and increase, deteriorating the microwave dielectric properties. The Q × f values are related to the microscopic morphology and packing fraction. αobs increases from 13.360 to 13.596, the same trend as the αtheo, suggesting that εr is mainly affected by the ion polarizability. Among all the samples, the optimum microwave dielectric properties of Zn1.76Mn0.04SiO3.8 ceramics were obtained by sintering at 1275 ℃ for 3 h:εr = 6.44(at 13.153 GHz), Q × f = 71,175.7 GHz,τf = − 50.7 ppm/℃. Due to its low dielectric constant and excellent quality factor, it will become the most promising electronic substrate material. [ABSTRACT FROM AUTHOR]

Sr0.975Sm0.025Ti1−xAlxO3 (x = 0, 0.005, 0.01, 0.015, 0.02, 0.025) ceramics were synthesized via solid-state reaction. The sample with an x = 0.005 doping concentration exhibited the optimal dielectric properties, with an electric constant of 8832 and a dielectric loss of tanδ = 0.019, measured at 1 kHz and room temperature. This sample also exhibited excellent frequency stability (ranging from 100 Hz to 1 MHz) and temperature stability (from room temperature to 200 °C). The activation energy calculation for the dielectric modulus relaxation peak, coupled with XPS results, indicates that in the sample with x = 0.005, there is a significant presence of oxygen vacancies and Ti3+ ions, which form defect complexes (Ti3+ − V O.. −Ti3+). These complexes restrict the delocalization of electrons, leading to electron pinning. Consequently, the sample demonstrates a high electric constant and low dielectric loss. In addition to the defect complexes, high grain boundary resistance reduces dielectric loss and enhances temperature stability. The findings of this study offer crucial conceptual insights for the defect engineering of complex perovskite materials, facilitating the development of doped strontium titanate ceramics with colossal permittivity. [ABSTRACT FROM AUTHOR]

The BaNb2V2O11 microwave dielectric material, synthesized using a solid-state process, was proposed for utilization as a temperature compensator in LTCC applications. XRD analysis indicated that all samples revealed a trigonal structure of the BaNb2V2O11 phase with the R3̅m (166) space group. Influence of lattice energy and bond energy on the dielectric characteristics were investigated. Correlation between the Full Width at Half Maximum (FWHM) of the primary Raman peak at 917 cm⁻1 and the Q × f value was also analyzed. The sample sintered at 860 °C exhibited remarkable microwave dielectric properties, including a high relative permittivity (εr) of 88.7, a high Q × f value of 2100 GHz, and a significantly positive temperature coefficient of resonant frequency (τf) of + 602.4 ppm/°C. This notably large positive τf value makes it an effective τf compensator. Furthermore, the high εr value indicates its suitability for use in decoupling devices or as dielectric resonators in 5G base stations. [ABSTRACT FROM AUTHOR]

This study explores the impact of small air gaps in high-temperature superconducting cables on the insulating material polypropylene-laminated paper (PPLP), and the aging rules and mechanisms of the insulating material during practical uses. An air gap discharge test platform was built to simulate air gap fault defects of superconducting cables in the real operating environment. Hierarchical clustering method was used to divide the gap discharge process of defect model into four stages. Insulation damage assessment was conducted on the intermediate layer PP of the superconducting insulation material PPLP at different discharge stages, revealing surface changes and periodic alterations in dielectric properties. The morphological features, roughness, infrared spectra, dielectric loss, surface resistivity, and other phase characteristics of the superconducting insulation layer material were analyzed at different stages of air gap defects. Molecular group cracking in PP was attributed to the bond breakage on the main chain. These findings provide insights into high-temperature superconducting cable insulation under air gap discharge and provide a guideline for practical applications in semi-conductive industries. [ABSTRACT FROM AUTHOR]

The rapid development of 5G and 6G technologies has led to an increased demand for microwave dielectrics ceramics. Microwave dielectrics ceramics with high Q value and low cost have attracted a lot of attention from researchers. Such as material sintered at relatively low temperature and cheap raw materials. Magnesium titanate (MgTiO3) is a material with excellent dielectric properties but requires high-temperature sintering. It is reported that substitution of Zn2+ for Mg2+ can lower sintering temperature and improve dielectric properties. Here, microwave dielectric properties and phase evolution of Zn-excess Mg0.95Zn0.05+xTiO3+x (x = 0, 0.025, 0.05, 0.075, 0.1) compositions were investigated. A moderate Zn-excess is found to promote formation of pure MgTiO3 phase with lower temperature. The composition with x = 0.05 sintered at 1300 °C possess optimal dielectric performance εr of 17.85, Q × f of 173,300 GHz (@11 GHz) and τf of − 52.04 ppm/°C with relative density of 97%. [ABSTRACT FROM AUTHOR]

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

(Zr0.8Sn0.2)TiO4 (ZST) microwave dielectric ceramic powder was synthesized by the hydrothermal-molten salt (HMS) method, and the effects of different molding methods on the physical phases, microscopic morphology, and dielectric properties of ZST ceramics were investigated. On this basis, ZST-NZ laminated composites were prepared, and the interfacial diffusion and laminated co-firing behaviors of the composites were studied more systematically. The results show that the heat-pressing process can be used to obtain high-frequency dielectric ceramics with more comprehensive performance. The dielectric properties (1 MHz) were ɛr = 40.5, tanδ = 1.32 × 10−3. ZST-NZ laminated composites have relatively tight interfacial bonding but show significant interfacial diffusion. The mutual diffusion of ZST-NZ composites follows the semi-infinite diffusion coupling model. Based on this diffusion model, the ionic concentration distribution function was established to simulate the interfacial diffusion of ions, and the diffusion coefficients and diffusion activation energies of Fe3+, Zn2+, Sn4+, and Zr4+ were calculated under different conditions. The magnitude of diffusion coefficients in the H-ZST-NZ diffusion couples was in the order of D (Fe3+) > D (Zn2+) > D (Sn4+) > D (Zr4+), and the magnitude of diffusion activation energies at 1275 °C was in the order of Qd (Zr4+) > Qd (Sn4+) > Qd (Zn2+) > Qd (Fe3+). The strong diffusion of Ti and Fe led to the decomposition of ZST and NZ ferrite, producing new TiO2 and Fe3O4 phases, which resulted in the degradation of the dielectric properties of the composites. [ABSTRACT FROM AUTHOR]

In this paper, Neodymium-doped Bismuth pyrochlore and its hybridized mixed phases (NdxBi2-xSn2O7 and Bi2O3–SnO2) were synthesized using the sol–gel autocombustion method. The synthesized material was annealed at 600 °C for three hours in a muffle furnace to ensure its crystalline structure, and X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis were conducted. Fourier Transform Infrared (FTIR) spectroscopy was employed to predict the phases and absorption frequencies. Subsequent to a comprehensive structural analysis, the dielectric properties, encompassing the real and imaginary components of Impedance, Electric modulus, dielectric constant, and tangent loss, were analyzed. This analysis spanned a frequency range from 1 MHz to 3 GHz, covering different doping concentrations. Notably, the maximum dielectric constant was attained for a doping concentration of x = 1.0 at 2.7 GHz. Conclusively, the obtained dielectric data suggest that the synthesized material holds promise for various applications, including high-frequency electronics, telecommunications, and wireless communication systems. [ABSTRACT FROM AUTHOR]

The solid-state reaction method was employed to synthesize (1−x)[0.90NaNbO3–0.10Bi(Mg0.5Ta0.5)O3]–x(Bi0.5Na0.5)0.7(Sr0.7La0.2)0.3Ti0.9Zr0.1O3, denoted as (1−x)(NN–BMT)–xBNSLTZ (xBNSLTZ). XRD analysis of xBNSLTZ confirmed that all samples possessed a pure perovskite structure. SEM micrographs demonstrated homogeneous grain distribution and minimal porosity. With an increasing concentration of BNSLTZ, there was a gradual reduction in average grain size. Impedance spectroscopy was utilized to investigate the electrical properties of xBNSLTZ across a frequency sweep of 10 Hz–1 MHz and over a temperature range of 420–560 °C. The complex impedance and modulus spectra reveal non-Debye-type dielectric relaxation, indicative of two contributing mechanisms: grain and grain boundary effects on conduction. Electric modulus analysis indicated that the low-frequency relaxation process was temperature independent. The dc conductivity variation with temperature follows the Arrhenius equation. The ac conductivity was found to adhere to Jonscher power law. The Ea (the relaxation activation energy) and Ec (conductance activation energy) confirmed the relaxation mechanism of 0.3BNSLTZ is dipolar conduction. The dielectric properties showed a significant dependence on both frequency and temperature. A dielectric anomaly pointed to the presence of a single relaxation behavior. It was observed that an increase in BNSLTZ concentration led to a decrease in the maximum dielectric constant. Optimum performance was obtained with the 0.3BNSLTZ ceramics, which has the smallest average grain size (1.54 μm), considerable resistance value (R ~ 1000 K Ω c m ), and moderate dielectric constant (εr ~ 600), superior to the pure NN-BMT ceramic. These results demonstrate that the electrical property of the xBNSLTZ ceramics have some potential value in the application of electrical materials. [ABSTRACT FROM AUTHOR]

This study explores the impact of crystallite size on the opto-dielectric properties of LiCu0.5Fe2-yCeyO4 (y = 0.0, 0.01, 0.02, 0.03, 0.04) nanospinel ferrites (NSFs) synthesized via sol–gel auto-combustion. X-ray diffraction (XRD) analysis confirmed the crystalline nature and phase purity, revealing variations in crystallite size within the nanoscale range. Fourier-transform infrared spectroscopy (FTIR) provided insights into chemical bonding, affirming the composition and structure reliability. Morphological characterization via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed the nanostructure, highlighting the influence of crystallite size on particle morphology, shape, and size distribution. Energy-dispersive X-ray spectroscopy (EDX) verified the presence of expected elements, with elemental composition offering spatial distribution insights. Inductively coupled plasma (ICP) analysis quantified elemental concentrations, focusing on Li, Cu, Fe, and Ce. Optical properties, including UV–vis absorption spectra, were measured to assess band gap energies. Dielectric measurements across a range of frequencies provided insights into the pure Li-Cu NSFs and Ce3+ doped Li-Cu NSFs dielectric response, revealing variations in dielectric constant and loss tangent with changing crystallite size. The findings highlighted the significant role of crystallite size in modulating both energy band gap and dielectric properties, essential for applications in high-frequency, photonics, electronics, and sensor technologies. [ABSTRACT FROM AUTHOR]

Thin films of cadmium oxide (CdO), cobalt oxide (Co3O4), and their composites were deposited on glass substrates at 360 ℃ using the spray pyrolysis method. The films underwent characterization through various techniques, including energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), X-ray diffraction (XRD), and ultraviolet–visible spectroscopy (UV–Vis). Hall Effect measurements were also conducted to assess the structural, optical, and electrical properties. The XRD analysis revealed crystalline structures with cubic symmetry for both CdO and Co3O4, and the Scherrer equation confirmed their nanomaterial nature. EDX results identified the distinct proportions of oxygen, cadmium, and cobalt in the films. On the other hand, the optical band gaps determined via Tauc plots indicated values of Eg1 = 1.54 eV and Eg2 = 2.01 eV for Co3O4, and Eg3 = 2.4 eV for CdO. As for the Hall Effect measurements, they were performed to determine a number of electrical parameters. The results showed that the addition of Co3O4 into CdO increased the sheet resistance of the composite. This research has potential applications in various areas, including the design of solar cells (photovoltaic devices) and the creation of new light-based devices (optoelectronic devices). Additionally, the dielectric functions of composites (CdO)x (Co3O4)1-x with varying compositions (x = 0.7, 0.5, and 0.3) were evaluated. The dielectric properties were experimentally measured from 350 to 2500 nm, and theoretical calculations were performed using mixing equations like Looyenga, Kim, and Bruggman, with the Looyenga model accurately depicting the dielectric properties of the materials studied. [ABSTRACT FROM AUTHOR]

We prepared bulk samples of SrLaLiTe1-xGdxO6; 0 ≤ x ≤ 0.3, using the solid-state method. Measurements carried out on the XRD data recorded at room temperature highlighted changes corresponding to the volume of the unit cell and angle β. Specifically, the undoped composition described a structure of the ordered type containing Li+ and Te6+. Calculations of the octahedral tilt angle indicated a transition from cubic to monoclinic symmetry, accompanied by bending and tilting of the B-O-B'(B = La, B' = Te/Gd) octahedra. FTIR measurements confirmed the existence of molecular bonds in all compositions. UV–visible spectroscopy results indicated a reduced bandgap energy, suggesting enhanced conductivity in the doped samples. SEM and EDX confirmed the elemental composition and revealed particle clustering. Impedance spectroscopy analysis demonstrated increased AC conductivity at higher frequencies. Additionally, a decrease in the grain resistance indicated single dielectric relaxation behavior. A relaxation phenomenon of the non-Debye type was revealed from the Cole–Cole plots attributed to the presence of imperfections within the samples. Dielectric properties showed a reduction in dielectric loss and constant, which was dependent on frequency, attributed to the decrease in overall polarization. [ABSTRACT FROM AUTHOR]

The present work explores a systematic investigation of the microstructural, optical, and dielectric properties of W1−xNixO3 (x = 0, 0.02, 0.04, and 0.06) samples and their application in supercapacitors. The sol–gel auto-combustion process was used to synthesize these samples, and a number of analytical techniques such as x-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Raman, Scanning Electron Microscopy (SEM), UV–visible spectroscopy, dielectric measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used to characterize them. The Rietveld refined XRD patterns confirm the monoclinic phase with space group P21/n in a single phase. FTIR spectroscopy confirms the functional groups associated with stretching and bending vibrational modes at various wavenumbers. Raman spectroscopy ensures the phase purity of the materials and shows a blue shift with Ni doping. SEM microscopy reveals a uniform surface morphology as well as particle agglomeration at the surface. UV–visible studies reveal a significant decrease in the bandgap (2.13–1.81 eV) as the Ni concentration is increased. Dielectric studies show that as the frequency rises, the dielectric constant decreases and becomes saturated at higher frequencies. The highest value of the dielectric constant (ε') is observed for the 4% Ni-doped WO3 sample. The electrochemical and capacitive properties have been characterized and studied using CV and EIS analysis. Cyclic voltammetry tests were carried out in the range of − 0.2 to 0.8 V with varying scan rates (5–100 mVs−1), exhibiting a significantly large area under the CV curve, hence higher values of specific capacitance. The maximum specific capacitance at a scan rate of 5 mVs−1 for each sample of W1−xNixO3 (x = 0, 0.02, 0.04, and 0.06) is found to be 126.671, 192.31, 278.52, and 128.58 Fg−1, respectively, in 2M KOH electrolyte. Thus, the synthesized samples exhibit potential for application as electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

The impact of Zn and Nb replacements on the dielectric, ferroelectric, and electrocaloric (EC) characteristics of BCZT−x%ZN ceramics was thoroughly studied. The introduction of Zn and Nb into BCZT−x%ZN not only enhances the dielectric permittivity but also reduces the curie temperature. By employing P–E hysteresis loops across a broad temperature range and applying externally induced electric fields, we investigated the EC temperature change (ΔT) using the Maxwell relation. The EC effect response was determined versus temperature for all BCZT−x%ZN ceramic compositions, ranging from x = 0 to 2%, through ferroelectric polarization and pyroelectric measurements. BCZT−0.5%ZN showed a maximum EC temperature change of ∆T = 0.701 K at 3 kV/mm, with a matching EC responsivity (ξ = ΔT/ΔE) of 0.233 K mm/kV. This discovery underscores the highly promising nature of this material family for electrocaloric applications in proximity to ambient temperatures. [ABSTRACT FROM AUTHOR]

The orthophosphates materials are one of the most important groups in the field technologically advanced materials that are accessible, inexpensive, and environmentally friendly. This materials are of great demand due to their various optoelectronic applications in recent years. In this study, a solid-state method was employed to synthesize the AgCoPO4 orthophosphate sample. Analyzing the XRD pattern, of the studied compound, confirms the triclinic phase with the P 1 ¯ space group. The examination of SEM analysis and energy dispersive spectroscopy (EDS) revealed the same morphology and different particle sizes. As for the EDX analysis, all chemical elements were detected and found in their appropriate ratio. Besides, the impedance spectroscopy measurements conducted at 100 Hz to 5 MHz and 473–673 K are used to investigate the electrical and dielectric properties of the AgCoPO4 compound. The frequency dependence of the conductivity of alternating current is explained using Jonscher's law. The calculated activation energy is in accordance with Arrhenius's behavior based on DC conductivity, which was determined to be 0.93 (2) eV. The primary transport mechanism is governed by the correlated barrier hopping model. A comparative study of impedance and modulus responses versus frequency suggests Cole–Cole behavior. deep investigation of the electric and dielectric performances demonstrated a significant dielectric constant (ε′ ∼ 104) at low frequencies and low dielectric loss at high frequencies. Thus, it highlights its exceptional dielectric potential, particularly in applications related to electronic capacitors. [ABSTRACT FROM AUTHOR]

The effects of cold sintering assisted two-step sintering on the structural evolution and microwave dielectric properties of Al2O3 ceramics are systematically investigated in this work. XRD analysis reveals that the crystal structure remains stable throughout the cold sintering and following high-temperature sintering processes. Rietveld refinement confirms the trigonal Al2O3 configuration and the absence of impurities. Increasing cold sintering pressure results in improved relative density, reaching over 94% after post-sintering at 1575 °C. Additionally, the sintering temperature of Al2O3 ceramics via cold-sintering assisted two-step sintering route is 100 °C lower than that via direct conventional sintering. The microwave dielectric properties, including εr and Qf, exhibit enhancements with increasing cold sintering pressure and post-sintering temperature. The measured εr closely aligns with the theoretical value, indicating a successful densification. Qf achieves its peak of 100,220 GHz at 1575 °C under 375 MPa, nearly 2 times higher than the value obtained at 125 MPa (53,280 GHz). The optimal microwave dielectric properties (εr = 9.67, Qf = 100,220 GHz, and τf = − 54.5 ppm/°C) are achieved at a cold sintering pressure of 375 MPa and post sintering temperature of 1575 °C. [ABSTRACT FROM AUTHOR]

Flash sintering is considered a promising energy-saving and efficient technology for preparing high-temperature ceramics. The effects of limited current on flash sintering parameters, microstructure, and electrical properties of (La1/2, Ta1/2)0.02Ti0.98O2 ceramic were investigated by the XRD, SEM, XPS, and precision impedance analyzer. With limiting current increase, the grain size of flash sintering sample increases gradually, and the relative density increases first and then decreases. The average grain size is about 1 μm, and the highest relative density is 96.9%. Joule heating runaway and oxygen vacancy defect lead to rapid densification of flash sintering La and Ta co-doped TiO2 ceramics. According to the EPDD model, doped La3+ and Ta5+ ions increase the concentration of oxygen vacancies and free electrons, lead to local polarization of carriers, and obtain a giant dielectric constant of ε' = 7.6 × 104 and low dielectric loss of tanδ = 0.11. At high temperature, electrons break free from the constraints of defect clusters and accumulate at the interface, leading to interface polarization due to the IBLC model. The giant dielectric properties originate from the combined effect of EPDD and IBLC model. [ABSTRACT FROM AUTHOR]

A series of single phase (Na1/2Eu1/2)xCa1−xCu3Ti4O12 (x = 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.35, 0.4 and 0.45) ceramics with different doping amounts were successfully prepared by high temperature solid-state reaction method. The microstructure, ion valence, and dielectric properties of the ceramics were systematically studied. The results indicated that with the increase of Na+ and Eu3+ ions concentration in (Na1/2Eu1/2)xCa1−xCu3Ti4O12 ceramics, Na and Eu elements accumulated at the grain boundaries of ceramics, thereby increasing the insulation of grain boundaries and effectively reducing the dielectric loss of the ceramics. However, the presence of Cu+ in (Na1/2Eu1/2)xCa1−xCu3Ti4O12 (x ≥ 0.3) ceramics with high doping content could affect the polarization mechanism inside the ceramics and improve their dielectric properties. The dielectric constant of (Na1/2Eu1/2)0.3Ca0.7Cu3Ti4O12 ceramics was as high as 25 282, with a dielectric loss of 0.061 (at room temperature and 10 Hz), and it had good dielectric stability. [ABSTRACT FROM AUTHOR]

Microwave ceramic with low‐sintering temperature is one of the most significant classes of materials to realize the multifunction and miniaturization of portable devices. In this paper, Bi6B10O24 ceramics using the solid-state reaction method are prepared with MoO3 addition, to achieve both low-temperature sintering and excellent microwave dielectric properties. It is demonstrated that MoO3 diffuses into the lattice of Bi6B10O24 to form a solid solution. The higher quality factor (Q × f) of the ceramic is successfully obtained and the temperature coefficient of resonant frequency (τf) is adjusted to near zero at the same time without much change in the dielectric constant (εr) due to the Mo6+ incorporation. Compared to Bi6B10O24 ceramics without addition, the optimum properties of εr = 13.9, Q × f = 37,000 GHz, τf = − 20 ppm/°C are achieved for Bi6B10O24 ceramics containing 19 mol% MoO3. The ceramics are potential candidates for ultra-low temperature co-fired ceramics (ULTCC) applications in wireless communication systems. [ABSTRACT FROM AUTHOR]

In this work, zinc sulfide (ZnS) QDs were synthesized using green technique with the help of Tabernaemontana divaricata flower extract as capping/stabilizing agent, characterized by different physical techniques, like XRD, FESEM, EDX, TEM, FT-IR, XPS, UV–Vis–NIR, and PL, and were compared with their pristine analogue. From XRD analysis, it is observed that the size of the synthesized ZnS QDs lie in 1.79–1.46 nm range and with addition of flower extract particle size decreases. FT-IR analysis indicated the functional groups present in the synthesized QDs. The direct energy band gap (3.21–3.51 eV) values as well as the refractive index values (2.28–2.33) of the QDs were calculated utilizing the absorption data. Due to various defect levels present in the ZnS QDs within the energy band gap, four peaks (three in visible and the other in NIR region) were observed in the PL spectra. Surface morphology and elemental composition of the particles were understood from FESEM and EDX studies. Dielectric constant, loss, and ac and dc conductivity of the materials were studied. At room temperature, all synthesized ZnS materials exhibited high dielectric constant ( ε r ) values in the low-frequency region. It is found that ε r values for pristine ZnS QD (~ 23,000) are much higher than the green ZnS QDs (~ 100–800) where overall dielectric loss is less than 2 which decreases with QD size. Results obtained from the characterization studies conducted on pristine and green-synthesized ZnS QDs elucidate that it is possible to effectively control the size, optical, and dielectric properties of the potentially important ZnS QDs through green synthesis technique. [ABSTRACT FROM AUTHOR]

The dielectric constant of polymers is low (low-ε′). A high-ε′ multifunctional nanomaterial must be added to the polymer in order to create a polymer composite with high values of the dielectric constant of the polymer blend. Composites prepared from such high-ε′ polymers are extremely beneficial for many energy storage devices and electrical devices such as transducers, piezo-sensors, hydrophones, microstrip antennas (used in artificial satellites for data detection) etc. In order to achieve the demands and needs of today for the society we prepared and design thin films using PMMA which is blended with poly vinylidene fluoride (PVDF) with high-ε′ value and further mixed with tin oxide (SnO2) nanoparticles in different weight ratios varies from 0.5 to 4 wt% categorizing sample as SP1—0.5 wt%, SP2—1wt%, SP3—2wt% and SP4—4wt% and these samples are synthesized by casting techniques using magnetic stirrer. The effect of varying SnO2 content on structure, chain segmental motion and dielectric properties of PVDF/PMMA blend have been investigated using X-ray diffraction (XRD), Infrared spectroscopy using FTIR and Impedance analyzer techniques. The structural characterizations showed that the SnO2 nanoparticles are immiscibly dispersed in PVDF/PMMA blend matrix, leading to a noticeable rise in the values of dielectric constant and electrical conductivity at constant frequency. On increasing the frequency at constant wt% of SnO2, a decrease in dielectric constant was observed. Such behavior in a lower frequency range can be attributed to the interfacial polarization effect (IPF) and remarkable increase in the molecular polarization at high frequencies. At high wt% of SnO2 in the polymer blend, nonlinear behavioral changes occur in the chain segmental dynamics, reflected by the trends of dc electrical conductivity. The electric modulus spectra were used to analyze the relaxation processes associated with the M–W–S mechanism and chain segmental motion in the polymer. [ABSTRACT FROM AUTHOR]

The MgTiTa2O8 ceramics were synthesized in the molten salt KCl. We have conducted an examination of the phases, microstructure, and microwave dielectric characteristics of MgTiTa2O8 ceramics. This investigation involved the use of X-ray diffraction (XRD), Rietveld refinement, and scanning electron microscopy (SEM). The result demonstrated that MgTiTa2O8 ceramics exhibited crystallization into a tri-rutile structure with space group P42/mnm (136). With the increase of temperature, the relative density gradually increases, which benefit the dielectric constant and Q × f value. However, as the temperature continues to rise, there is a decrease in the εr and Q × f value, which can be ascribed to over-sintering of the sample and a resultant reduction in the uniformity of grain size. The correlation between oxygen octahedron distortion dielectric, bond strength, packing fraction, and properties of microwave is discussed. The Q × f value increases with the increase of atomic packing density. The value of τf decreases with the increase of bond energy and has no direct relation with the distortion of oxygen octahedron. The MgTiTa2O8 ceramics sintered at 1150 °C exhibited superior dielectric characteristics of εr = 35.1, Q × f = 32,200 GHz, τf = + 95.4 ppm/°C. [ABSTRACT FROM AUTHOR]

This study is dedicated to a comprehensive investigation into the influence of barium strontium titanate (BST) doping on the microstructure, dielectric properties, and electrical behavior of calcium copper titanate (CCTO) ceramics. The research involves a systematic analysis of a series of (1-x) CaCu3Ti4O12 - x Ba0.6Sr0.4TiO3 [(1-x) CCTO/x BST] composite samples, with varying BST ratios (x = 0, x = 0.025, x = 0.075, x = 0.15, and x = 0.2). These composites were synthesized through the solid-state reaction method and subsequently sintered at 1050 °C for a duration of 12 h. The investigation provides detailed insights into microstructural features, dielectric characteristics, and electrical responses, thereby unraveling the intricate correlations between BST content and the resultant material properties. Notably, the sample with x = 0.025 exhibited the highest dielectric constant (εr ≈ 2.71 × 104) and the lowest dielectric loss (tanδ ≈ 0.052) at a frequency of 1 kHz. Furthermore, the optimized composition (x = 0.025) demonstrated exceptional breakdown electric field (Eb ≈ 1284 V/cm) and notable grain boundary resistance (Rgb ≈ 8.8 × 106 Ω). These findings collectively contribute to an enhanced understanding of the impact of BST doping on the distinct characteristics of CCTO ceramics, opening avenues for tailored applications in advanced electronic devices and energy storage systems. [ABSTRACT FROM AUTHOR]

A novel samarium-based cerium-doped ceramic manganite of Sm0.3Ce0.2Sr0.5MnO3 (SCSMO) was prepared via the high-temperature solid-state reaction method. The experimental investigation focused on exploring the crystallographic, morphological, and dielectric characteristics of the perovskite ceramic. Rietveld's refinements of X-ray diffraction patterns confirm that a single-phase orthorhombic crystal structure with the space group of Pnma (62) without any detectable impurity phase is obtained for ceramic perovskite. Based on X-ray data, the average size of crystallites was determined to be 80.9 nm using the Williamson–Hall method. The surface morphology analysis through scanning electron microscopy (SEM) revealed distinct grains with an average size of 8.22 μm. The study utilized dielectric and impedance spectroscopy at different temperatures and frequencies to thoroughly examine the electrical parameters of SCSMO. Through this analysis, a relationship between the conduction mechanism and structural qualities was established. [ABSTRACT FROM AUTHOR]

This study investigated the impact of magnesium doping on structural, optical, and dielectric properties of zinc oxide. Magnesium-doped ZnO (Zn1−xMgxO) samples were synthesized and characterized with varying doping levels (x = 0, 0.01, 0.02, 0.03) using solid state reaction, employing techniques including X-ray Diffraction(XRD), Field Emission Scanning Electron Microscopy (FESEM), Impedance Spectroscopy and Diffuse Reflectance Spectroscopy (DRS). The synthesized samples show single-phase hexagonal wurtzite structure, indicating successful doping of magnesium in ZnO lattice. FESEM micrograph revealed voids in doped samples. Doping reduces the dielectric constant of ZnO and shows dielectric loss > 200 °C in doped sample. Magnesium doping decreased ZnO's band gap, altering its electronic properties and optical behavior. Urbach energy increased with doping and inversely linked to dielectric constant. [ABSTRACT FROM AUTHOR]

Six series of strontium lead-borate blocks with general chemical form (60-x)B2O3-10Li2O-20ZnO-10PbO-xSrO: x = 0 (BLZPS-0)—25 (BLZPS-25) mol% were synthesized by the melt-quench method. FTIR spectroscopy, density, and γ-rays buildup factors of the prepared glasses were investigated. Dielectric spectroscopic properties of glasses are conducted during frequencies interval from 50 Hz to 5 MHz at room temperature. Density of BLZPS glasses increased from 3.2824 g/cm3 to 3.8717 g.cm−3 as the SrO mol% enhanced from 0.0 to 25.0 mol%. Relative portion of BO4 (N4) enhanced at the cost of BO3 (N3) relative portion with an increase in SrO content up to 10 mol%, and then back transformation of BO4 to BO3 is observed by increasing SrO over 10 mol%. In terms of dielectric spectroscopy, the real part of permittivity was decreased by SrO doping up to 10 mol% and then enhanced. The increase in glass matrix solidity caused by switching from NBOs networks "BO3" to BOs networks "BO4" with an increase in strontium content up to 10 mol% is considered the responsible for the reduction in real part of permittivity by SrO content up to 10 mol%. The relaxation peaks detected in tan δ were enhanced by strontium (Sr) doping. The optical energy gap (Eg) varied 2.79 eV to 2.91 eV. The mass attenuation coefficient (MAC) of these blocks was boosted from 41.322 to 42.268 cm2/g when E = 0.015 MeV. Sample encoded BLZPS-25 possessed the lowest values of half value layer (HVL), but highest values of Zeq along all energy range. The exposure-(EBF) and energy-absorption-(EABF) buildup parameters were increased with increasing SrO mol% in these networks. In conclusion, BLZPS-25 glass demonstrates a higher effectiveness in absorbing gamma radiation compared to other samples. [ABSTRACT FROM AUTHOR]

Sintering AlN ceramics at lower temperatures and suppressing the formation of Al2O3 are challenges. This study is focused on addressing the above problems. Zinc oxide (ZnO)-added AlN ceramics have been prepared, and the effect of ZnO on structural, dielectric, and electrical properties is investigated systematically. AlN (pure and additive) ceramics are sintered using the powder bed method at 1700 °C in the presence of nitrogen flow. In addition, the small initial particle sizes and ZnO also help decrease the sintering temperature to 1700 ℃ and densify AlN at lower temperatures due to the formation of the eutectic phase around 1400 °C. The XRD pattern of ZnO-added AlN ceramics revealed that the sintered ceramics are pure AlN phase, wurtzite structure with P63mc space group of space group number 186. The Raman spectrum of all sintered AlN–ZnO composites exhibited six vibrational modes of wurtzite AlN. The XPS results confirm Al 2p, Zn 2p, N 1s, and O1s presented in the AlN–15ZnO composite ceramic. This result proves oxygen in the AlN–15ZnO composite ceramics on the surface, not in grains. The powder bed prevents the formation of Al2O3 and enhances densification. The best additive AlN–15ZnO composite obtained dielectric permittivity of 5.5 to 7.4 in the variation of temperature from 30 to 500 °C. The impedance spectroscopy revealed that the AlN–ZnO composite ceramics contain non-Debye-type relaxations. The best microwave dielectric properties (εr = 7.195 and tanδ = 4.90 × 10−3) is obtained for the best composite AlN–15ZnO ceramic for transmission of signals with high speed in electronic applications. [ABSTRACT FROM AUTHOR]

Improving the compatibility and dispersion between nanoparticles and polymers has become the key to enhance the dielectric properties. In addition, dielectric materials should also have excellent dielectric and thermal stability to meet the application under extreme conditions. Herein, we synthesized a core–shell structure BST@HBPI and BST@HBPI/PEI nanocomposite films. HBPI owns a chemical structure similar to polyetherimide (PEI), and the dipole moment of the polar group contained in it is small, so it can enhance the interface interaction between the nanoparticles and the matrix, hence effectively inhibiting the free charge, and reducing the leakage current in composite. The results show that the introduction of HBPI not only effectively improves the compatibility and dispersion of nanoparticles and polymer matrix, but also greatly enhances the dielectric properties and energy storage properties of nanocomposites. Under an electric field of 200 kV mm−1, the minimum charge-discharge efficiency of BST@HBPI/PEI reaches 74.36%, which is 1.33 times of that for BST/PEI (55.97%), and the maximum discharge energy density reaches 5.01 J cm−3, which is 1.28 times comparing to BST/PEI (3.89 J cm−3). Meanwhile, due to the preeminent electrothermal stability of nanoparticles and matrix, nanocomposites can maintain excellent dielectric properties at high temperatures. The dielectric constant of 10 vol% BST@HBPI/PEI (7.56 J cm−3) is 93.24% at 25 °C (8.113 J cm−3) while the dielectric loss at 200 °C (0.04287) is 114.29% when comparing to that at 25 °C (0.03751). This work provides a promising method for manufacturing dielectric materials that can work in extreme environments. [ABSTRACT FROM AUTHOR]

In this research work, we demonstrate a detailed and systematic investigation of the structural, microstructural, dielectric, electrical, and magnetic properties of the Mg-doped BaFe0.5Nb0.5O3 complex perovskite prepared through the conventional ceramic method. While electron microscopic imaging depicts the heterogeneous distribution of non-uniform shape grains, X-ray diffraction analysis reveals the monoclinic crystal structure of the sample. The elemental analysis by energy-dispersive X-ray spectroscopy confirms the presence of expected elements in the sample. Besides valency identification of the involved elements, the existence of oxygen vacancies is evident from X-ray photoelectron spectroscopy analysis. Dielectric and electrical properties are investigated in terms of dielectric constant, dielectric loss, complex impedance, and conductivity studies. Magnetic analysis reveals that the sample exhibits weak ferromagnetism at room temperature. The obtained results from various characterizations signify the suitability of this sample for modern electronic device-based applications. [ABSTRACT FROM AUTHOR]

The manufacture of nanotechnology is evolving quickly, and it is anticipated that the key developments will have a substantial impact on both business and science and be applicable in a wide range of fields. Cobalt ferrite (CoFe2O4) nanoparticles have been thought of as one of the top contenders in this field. The goal of the current work is to determine how the chelating agent affects on the physical properties of Nd+ 3-doped CoFe2O4 (CFO) nanomaterial. Sol–gel auto-combustion method with different chelating agents such as oxalic acid (OA), citric acid (CA), and ethylenediamine tetraacetic acid (EDTA) was used to prepare the Nd+ 3 ion-doped cobalt ferrites with the formula CoNd0.075Fe1.925O4(CNFO). X-ray diffraction (XRD) data gathered from the synthesized samples reveal that they have a single-phase spinel structure without any impurity phase or unreacted starting materials. The average particle sizes 28, 35, and 19 nm were observed through scanning electron microscopy (SEM) for the CNFO samples obtained from OA, CA, and EDTA, respectively. The magnetization value of CNFO obtained from EDTA is 76.79 emu/g, which is superior to that of CNFO obtained from OA (58.48 emu/g) and CA (61.12 emu/g). Temperature-dependent (in the range of 300-500 K) dielectric constant, dielectric loss, and electrical conductivity are also investigated as a function of frequency. The calculated grain boundary activation energy for the CNFO nanomaterial obtained from EDTA is 0.64 eV, and which is higher than that of OA (0.54 eV) and CA (0.58 eV). The nano-sized CNFO synthesized using the EDTA as a chelating agent having the lesser crystallite size (19 nm) and high magnetization (76.79 emu/g) as well as high coercivity (2917 Oe), and hence, it can be used for magnetic data storage and magneto-recording systems. [ABSTRACT FROM AUTHOR]

We have prepared (Gd1−xHox)3Fe5O12 (x = 0.0 to 1.0) samples by solid-state reaction method at a sintering temperature of 1400 °C for 8 hours. The formation of single phase is verified with refinement of X-Ray Diffraction patterns using I a 3 - d space group. The lattice constant, bond length, and F e a - O - F e d bond angle are showing a decreasing trend with Ho substitution which also results in decrease in ferrimagnetic (FIM) transition temperature from 553 K (x = 0.0) to 543 K (x = 1.0) . Additionally all the samples show magnetic compensation in between 145 K to 295 K. The hysteresis loops shows magnetic saturation at ambient as well as low temperature. We have also observed an increment in coercivity as we go from room temperature to 5 K because of higher magnetic anisotropy at low temperature. The Nyquist plots reveals the depressed semicircle behavior which shows the deviation of these systems from ideal Debye type relaxation. Moreover, ac conductivity is analyzed and it decreases with Ho substitution due to the drop in charge carriers concentration. All the samples represent magneto-electric coupling about ferrimagnetic transition temperature. [ABSTRACT FROM AUTHOR]

The abundant requirements of smart terminals promote the rapid development of dielectric materials to further realize the integration and miniaturization of electronic devices. In this work, based on a solid-state reaction method, (In0.5Ta0.5)0.1Ti0.9O2 (ITTO) ceramics with dense microstructure, colossal permittivity of 1.18 × 105, and ultralow dielectric loss of 0.0072 were obtained at 1 kHz and room temperature. In addition, the temperature coefficient stability and range of the ITTO ceramics were between ± 3.3% and − 100 to 235 °C, satisfying X9D (− 55 to 200 °C, Δεr/ε25°C < ± 3.3%) requirement at 1 kHz. The dielectric mechanisms could be connected to the electron hopping and internal barrier layer capacitor (IBLC) effects. Thus, the acquired ITTO ceramics have advanced advantages with excellent dielectric properties and temperature stability in the practical applications of microelectronic fields. [ABSTRACT FROM AUTHOR]

Adding nanoparticles (NPs) to a base polymer matrix which is known as nanocomposites results in improving its dielectric properties. In this paper, the evaluation of polyvinyl chloride (PVC)/silica nanoparticles (SiO2) nanocomposites is carried out considering the effect of water absorption. PVC nanocomposites are prepared considering different filler loadings of SiO2 NPs (1, 2.5, 5, and 7.5 wt%). The preparation of PVC/SiO2 nanocomposites is chemically carried out by casting the solution. The chemical structure of PVC/SiO2 nanocomposites after water adsorption is investigated by Fourier transform infrared (FTIR) spectroscopy. The effect of water absorption is carried out by immersing nanocomposite samples in tap water. The AC breakdown strength of PVC/SiO2 nanocomposites is measured before and after water immersion. In addition, both dielectric constant (έ) and loss tangent (tan δ) are measured considering different frequencies before and after the water immersion. The results show that the dielectric properties of PVC/SiO2 nanocomposites are significantly affected by water absorption, where PVC/SiO2 nanocomposite sample with filler loading of 7.5 wt% is found to have lower water absorption compared to the other adopted filler loadings. Under the effect of water absorption, the breakdown strength of the base and PVC nanocomposite samples is decreased, and its value for PVC nanocomposite still exceeds the base polymer. Finally, the dielectric constant and dielectric loss of PVC samples are increased under the effect of water absorption. The increase in dielectric constant and dielectric loss is small at the higher filler loadings. [ABSTRACT FROM AUTHOR]

The aim of the work is to study the impact of different concentration of zinc oxide (ZnO) nanofillers on the thermal, molecular dynamics and dielectric properties of poly(vinyl alcohol) (PVA) nanocomposites. The PVA–ZnO nanocomposite films are prepared by varying the loading of ZnO ranging from 0.5 to 2 wt% by solution casting method. The films are characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, UV–visible absorption spectroscopy. In PVA–ZnO nanocomposite film, hexagonal phase (P63-mc) of ZnO with PVA peak at 19.91 is found. The calculated size of ZnO is 21 nm. Further, Thermogravimetric, differential scanning calorimetry and dielectric measurement of PVA–ZnO nanocomposite films are showing good results at 1wt.% ZnO nanofillers in PVA. Improved thermal stability with about 45% residual weight at 325 °C and crystallinity (16.5%) at 300 °C are obtained for1wt% ZnO in PVA. Integration of ZnO nanoparticles into PVA exhibit greater effect on optical, thermal, and dielectric properties due to large surface area and availability of more interfacial sites for interactions. FTIR study confirms the chemical interaction of OH and C–O groups of PVA with surface of ZnO. At 1wt% ZnO nanofillers in poly (vinyl alcohol) has shown higher optical band gap, melting temperature, and change in enthalpy. Dielectric properties are evaluated at frequency ranging from 100 to 5 MHz. Among all PVA–ZnO nanocomposite films, 1wt% ZnO in PVA has presented relatively high dielectric constant (12.46) at 4 MHz with low tangent loss. It is attributed to accumulation of charges between boundaries of ZnO and PVA. Thus, the present comprehensive study provides an insight into the fabrication of PVA–ZnO nanocomposites for polymeric electronic device in microwave frequencies and optical sensor. [ABSTRACT FROM AUTHOR]

In this paper, stannic sulfide(SnS2) and gallium sulfide (GaS) crystals were grown by the chemical vapor transmission (CVT) method. Correlation analysis of X-ray diffraction, X-ray photoelectron spectroscopy and Raman vibrational modes of the two materials proved the high quality and purity of the sample growth. The absorption characteristics of the two materials were measured by spectrophotometer, and it was found that SnS2 and GaS crystals had absorption peaks at 390 nm and 460 nm, respectively. The corresponding band gap was calculated by the Tauc diagram. In addition, the dielectric response and optical properties of SnS2 and GaS crystal at wavelengths from 250 to 1000 nm were investigated by using ellipsometry and first-principles calculations. Similar broad and low absorption bands of both materials were found in the visible and infrared regions, and a high extinction coefficient was found in the ultraviolet region, which facilitates their use as corresponding photodetectors. These results are helpful for the study of the physical properties of SnS2 and GaS crystals and their related applications. [ABSTRACT FROM AUTHOR]

To solve the problem of corona discharge generated by the stator wire rod of large high-voltage motors, anti-corona technology should be developed rapidly to ensure the safe operation of power generation systems. A nonlinear anti-corona material is often used to coat the primary insulation at the end of the stator rod to improve the unevenness of the electric field and to reduce the problem of shortening the service life of the primary insulation caused by the uneven phenomenon of field strength. It is imperative to study composites with good nonlinear electrical conductivity properties. In this paper, Tetra-needle-like ZnO whiskers (T-ZnOw) with a three-dimensional four-needle three-dimensional structure was added to the montmorillonite/silicon carbide/epoxy (MMT/SiC/EP) composite system to improve the electrical properties of the hybrid system, and T-ZnOw/MMT/SiC/EP micro-nanocomposites were prepared. The result of dispersion and interfacial overlap of inorganic fillers in the matrix was shown by scanning electron microscope. The conductivity, breakdown, and dielectric properties of the composites were tested. The results show that T-ZnOw can constitute an excellent conductive path inside the composite and reduce the threshold field strength of the composite. It improves the electrical conductivity and nonlinear coefficient of the composite. The content of T-ZnOw is 1 phr, which can effectively enhance the breakdown field strength of the composite. Its range of 9 phr reduces the relative dielectric constant and the dielectric loss angle tangent value. [ABSTRACT FROM AUTHOR]

In this work, a novel ceramic sample (1-x) Ca0.9Sr0.1Cu2.9Mg0.1Ti4O12 (CSCMTO) – x SrTiO3 (STO) (with x = 1, 3, and 10 weight%) was suggested by combining two oxide phases to create a new system. All the ceramic samples were prepared by solid-state reactions. The impact of the STO phase on the structure and dielectric properties of CSCMTO ceramic was analyzed through X-ray diffraction, scanning electron microscopy, Raman, and dielectric measurements. The increase in STO content brings about a decrease in mean grain size. The Raman and EDS measurements indicate the presence of STO and TiO2 phases at grain boundaries. The dielectric constant values of ceramic samples range from 103 to 104. They decrease progressively with the addition of the STO phase, accompanied by a reduction in the dielectric loss. The 0.9CSCMTO − 0.1STO reveals the lowest dielectric loss in the order of 0.031 at 10 kHz. Additionally, the STO phase plays a critical role in the enhancement of nonlinear properties. The 0.97CSCMTO-0.03STO shows the best value of breakdown voltage (Eb ≈ 1820 V/cm) as well as the highest nonlinear coefficient (α ≈ 3.55). A heterogeneous microstructure with improved grain boundary properties was shown by impedance spectroscopy. The high grain boundary resistance is responsible for the reduced dielectric loss and improved breakdown voltage. [ABSTRACT FROM AUTHOR]

The low-melting Bi2O3–B2O3–SiO2–ZnO glasses doped with two different modifier oxides (BaO and MgO) are synthesized using sol-gel method. The prepared samples are characterized using various experimental techniques such as differential thermal analysis (DTA), X-ray diffraction (XRD), and the impedance instrument to study their structure, thermal, and dielectric properties. The X-ray diffraction patterns reveals the amorphous properties of all the samples, while crystallization of BaO1.3 and BaZn2Si2O7 is formed and the diffraction peaks become weak with the increase of MgO content. The porous characteristics were observed in the scanning electron microscopy (SEM) images and the pore size distribution is mainly in the meso- and macro-range. The glass transition temperature decreases from 474.4 to 471.7 °C with the increase of MgO content, while the glasses become more thermally stable against crystallization. The glass structure is shown that Bi3+ cations were incorporated in the glass structure as pyramidal [BiO3] and octahedral [BiO6] units. With the concentration of MgO increases, the [BO4] units would transform to [BO3] and form non-bridging oxygens, which may destroy the original network structure of glasses and result in the increase of dielectric loss and dielectric constant. Furthermore, the decrease in chemical stability with the content of MgO increases can be attributed to the weakening of the glass structure. [ABSTRACT FROM AUTHOR]

In the last two decades, graphene oxide (GO) has gained popularity because of its multiple features and smart use in various fields in many areas. The abundantly rich metal oxide (MO) is added as a fuel component to deliver a good-quality engine for sustainable growth and applications. This review highlights the dielectric properties of graphene oxide/metal oxide nanocomposites (GO/MOs) and has established a detailed investigation of energy storage analysis. In this work, the critical examination of the dielectric behaviour of mentioned nanocomposites is studied at several frequencies and temperature ranges. Here, we tried to address and resolve a few challenges related to the development of the dielectric properties of nanocomposites. The development of good dielectrics solely depends on factors such as synthetic methods, toxicity level, chemical environment, morphological attributions, particle size, dangling patterns, defects and pores, energy density, nucleation crystal growth, and frequency–temperature dependency behaviours. The GO/MO nanocomposites include MOs such as transition MO, SnO2, ZnO, CuO, Fe2O3, Ag2O, Al2O3, TiO2, and other metal oxide-based perovskite oxides that show extensive applications and dielectric behaviour with the ε′ up to 106 with a maximum loss of 10 at different parameters. The inertness, robust attitude, and high stability of such nanocomposites also have increased their use in chemical industries, modern medical apparatus, and prosthetics in the bio-engineering field, petroleum, space vehicles and ballistics, microwave dielectrics, solid electrolytes, supercapacitors, and batteries. Furthermore, this discussion gives an idea of up-to-date achievements, current trends, and future directions in research on GO/MO nanocomposites for better performance in the enhancement of energy storage attitude and dielectric response. [ABSTRACT FROM AUTHOR]

In this paper, the variation of the dielectric properties of metatitanic acid and metatitanic acid–titanium carbide mixtures with apparent density and temperature at 915 MHz were systematically investigated by resonant cavity perturbation. The phase transition of TiO2 was determined by an X-ray diffractometer and Raman spectroscopy. The optimal dielectric properties are achieved when the apparent density of the material is 0.50 g/cm3 at 25 °C. At high temperatures (> 850 °C), the dielectric properties of the metatitanic acid–titanium carbide mixture are significantly improved due to the phase transition of TiO2. Meanwhile, the reflection loss calculation shows that the mixture's electromagnetic reflection loss decreases with the increase in the titanium carbide ratio; 9% of the mix is the best ratio, indicating that metatitanic acid has a better microwave absorption effect under the action of titanium carbide additives. In addition, the XRD and Raman analysis shows that it is feasible to prepare rutile TiO2 by low-frequency (915 MHz) microwave heating the metatitanic acid–titanium carbide mixture. [ABSTRACT FROM AUTHOR]

In this paper, calcium-doped zinc oxide (Ca/ZnO) nanopowders were elaborated via a the sol–gel process. X-ray diffraction analysis of Ca/ZnO nanopowders shows a hexagonal wurtzite structure and that the calcium atoms are successfully inserted into the ZnO lattice. The morphological study reveals that these Ca/ZnO nanopowders are made up of nanoparticles and confirms the hexagonal plane to the prepared nanopowders. The Ca doping of the Ca/ZnO nanopowders considerably improved their crystalline quality and allowed us to make dielectric measurements. During the dielectric processes in the sample, the physical parameters of Ca/ZnO nanopowders at various temperatures 300–450 K such as real part (ε′), imaginary part (ε″) and loss tangent (tanδ) were examined. Obviously, the optical results reveal that the band gap of Ca/ZnO nanopowders prepared by sol–gel process varies in the range of 3.34 to 3.29 eV. In addition, the composition developed by the sol–gel technique exhibits an evolution of the band gap which can be useful for various applications. [ABSTRACT FROM AUTHOR]

CaO-B2O3-SiO2/Al2O3/SiO2 composites were developed for low-temperature co-fired ceramic (LTCC) applications, and the sintering behavior, phase compositions, microstructure, dielectric properties, and mechanical properties were investigated in the present work. The results showed that an appropriate amount of silica could reduce the dielectric constant and improve the dielectric properties of the composite material, which is of great significance for improving the signal transmission rate, and reducing the signal transmission loss and delay. The CBS/Al2O3/SiO2 glass ceramics with 32 wt% Al2O3 and 16 wt% SiO2 sintered at 850 °C for 30 min achieved excellent comprehensive performance with buck density of 2.88 g/cm3, εr of 6.76, tanδ of 1.12 × 10−3(7 GHz), CTE value of 7.42 ppm/ °C, and flexural strength of 207.8 MPa. Moreover, the composites matched well with the silver electrode, establishing an extremely promising material for LTCC applications. [ABSTRACT FROM AUTHOR]

The impact of the inclusion of nickel-coated multiwalled carbon nanotube (Ni-MWCNT) filler in poly(vinylidene fluoride) (PVDF) matrix is reported in the present work. The fabricated flexible composite systems are characterized to study the behavioral changes in optical, electrical, dielectric, and magneto-dielectric aspects. The optical band gap and activation enthalpy have been effectively tuned by adding Ni-MWCNT filler. The optical energy band gap of the composite is significantly reduced with the inclusion of Ni-MWCNTs. The composite films possess enhanced dielectric permittivity and less dielectric loss than pristine PVDF film. At room temperature and 10 kHz frequency, the dielectric permittivity of Ni-MWCNT-PVDF is 20, but for pristine PVDF, it is 6. Due to the incorporation of Ni-coated MWCNT in ferroelectric PVDF, the higher magneto-dielectric coupling is achieved, which facilitates Ni-MWCNT-PVDF film as a promising material. [ABSTRACT FROM AUTHOR]

The BiFeO3/SiO2 composite films were deposited on Indium Tin Oxide (ITO)/glass by alternating evaporation method and post-annealing process. The effect of SiO2 layers with different thicknesses on the dielectric properties and energy storage performance are investigated. Due to the high breakdown strength, BiFeO3/SiO2 composite film demonstrates an optimal energy storage density of 34.8 J/cm3, excellent efficiency of 87.6%, as well as good thermal stability. The introduction of SiO2 layer greatly inhibits the chemical valence fluctuation of Fe ions and reduces the leakage current. Our work provides a useful and economical method to improve the energy storage performance of film capacitors. [ABSTRACT FROM AUTHOR]

Field grading composites showing nonlinear conductive performance are usually applied to protection for electrical systems. In this work, polyetherimide (PEI) matrix composite films with field-dependent nonlinear conductive behavior were fabricated by using a typical type of transition metal dichalcogenides, MoS2 as filler. The MoS2 filled PEI composite film showed a nonlinear coefficient of 6.92 at a relatively low filler content of 15 phr, which is the percolation threshold of this kind of composite film. Nonlinear conductive behavior of the MoS2/PEI composites was driven by tunneling effect. Conductivity of the 20 phr of MoS2 filled composite film increased for almost 3 magnitudes within 20 kV/mm. Enhanced dielectric constant was brought to PEI by the MoS2 fillers. The PEI containing 20 phr of MoS2 showed a dielectric constant of 6.1 at 1 kHz with dielectric loss still being low. This work revealed the potential of MoS2 being adopted as filler of field grading composites. [ABSTRACT FROM AUTHOR]

A series of (1−x)(NaBi)0.5MoO4–xBiPO4 microwave dielectric ceramics with ultra-low sintering temperatures (< 700 °C) are introduced in this work. The phase compositions, microwave dielectric properties and temperature dependences were studied. A small amount of BiPO4 occupies the scheelite position forming a solid solution. Tetragonal scheelite phase together with low temperature phase (LTP) and high temperature phase (HTP) coexist in the (1−x)(NaBi)0.5MoO4–xBiPO4 microwave dielectric ceramics. The scheelite phase and HTP dominate the composition sintered at relatively low temperatures of 600–650 °C. With x increasing from 0 to 0.6, the microwave permittivities, Q×f and τf values increase first and then decrease with εr = 37.6 – 26.8, Q×f = 17,500 – 5500 GHz, and τf = (− 3.3) – 109.5 ppm/ °C. When x = 0.5, the microwave dielectric ceramic sintered at 650 °C exhibits optimal temperature stability with τf = − 0.3 ppm/ °C, and the dielectric properties at low frequencies have a good temperature stability in a wide temperature range of − 170 and 200 °C. Meanwhile, the (NaBi)0.5MoO4–BiPO4 ceramic shows a good chemical compatibility with aluminum (Al) electrode material, making it promising for the ULTCC application. [ABSTRACT FROM AUTHOR]

In this report, transparent glasses of borate-based glasses with molecular formula xNb2O5–25CaO–60B2O3–15ZnO: x = 0.0 (Nb0.0), 0.2 (Nb0.2), 0.4 (Nb0.4), 0.6 (Nb0.6), 0.8 (Nb0.8), and 1.0 (Nb1.0) mol% have been synthesized using the melt-quenching technique. Physical as well as various elasto-mechanical moduli of the proposed glass systems have been reported. Dielectric spectroscopy of glasses has been investigated in the frequency range from 50 Hz < f < 5 MHz at room temperature. Photon attenuation capacities of Nb0.0–Nb1.0 glass samples have been tested using Phy-X/PSD software. Density (3.261–3.312 g.cm−3) and molar volume (20.849–21.335) of the proposed glasses gradually enhanced as Nb5+ ions increased in the glasses network. The elastic-mechanical moduli are enhanced by increasing Nb5+ ions. The dielectric parameters including their loss (tanδ) were greatly enhanced by introduction of Nb5+ ions into the glasses network. Values of the mass-attenuation constant (µm) are gradually surged with as a function of the Nb5+ ions molar fraction. It is found that, the Nb1.0 glass sample (with highest Nb2O5 content) achieved the maximum µm and the glass sample encodes as Nb0.0 (with lowest Nb2O5 content) has the least values of µm compared with other glasses. Both half (T1/2) and tenth (T1/10) value layers as radiation-shielding parameters for the proposed glass systems obeyed the following sequence: (T1/2,T1/10)Nb0.0> (T1/2, T1/10)Nb0.2> (T1/2,T1/10)Nb0.4> (T1/2,T1/10)Nb0.6> (T1/2,T1/10)Nb0.8> (T1/2,T1/10)Nb1.0. The findings confirm that the Nb0.1 glass has the finest radiation-protection coefficients among all studied glass samples. In addition, the current glasses (Nb0.0–Nb1.0) are suitable as radiation-shielding material than OC, HSC, and ILC concrete. [ABSTRACT FROM AUTHOR]

The distribution of functional filers in polymer matrix composites has a decisive effect on the material properties, however, functional fillers cannot be distributed in an orderly way and orientation in the polymerization system under natural conditions. It was found that the application of external field in the preparation process of materials can effectively improve the dispersion of functional fillers, and induce the orderly orientation of functional fillers, which can endow polymer matrix composites with excellent properties. In this paper, a novel core–shell structural nanorod with magnetic rod-shaped zinc ferrite (ZnFe2O4)(R-ZFO) as core and barium titanate (BaTiO3)(BT) as shell was successfully prepared by sol gel method. Then this core–shell nanorod were doped into the polyvinylidene fluoride-co-hexafluoropropylene (P(VDF-HFP)) to prepare the composites. The arrangement of ZnFe2O4@BaTiO3 nanorod in P(VDF-HFP) was controlled by a parallel magnetic field during the hot-press to obtain an ordered directional arrangement. The microstructure and properties of composites were investigated and the orientation effects of ZnFe2O4@BaTiO3 along the electric field orientation on the dielectric performance of P(VDF-HFP) composites were also analyzed. Results showed that ZnFe2O4@BaTiO3 prepared in this experiment are composed of a core–shell particle with a magnetic core and a dielectric shell, the core–shell particle can turn under the action of a magnetic field, thus forming an oriented structure in the composite film. The dielectric properties of ZnFe2O4@BaTiO3-P(VDF-HFP) composites were related to the anisotropy of ZnFe2O4@BaTiO3. When the orientation of ZnFe2O4@BaTiO3 is parallel to the electric field, the highest dielectric constant of the polymer composite with 80 vol% ZnFe2O4@BaTiO3 reaches as high as 27.77 at 100 Hz, which is 28% higher than that of the non-oriented polymer and 113% higher than that of the pure polymer. when the filling ratio is 40 vol%, the energy storage density of ZnFe2O4@BaTiO3-P(VDF-HFP) composites is 1.18 higher than that of non-oriented composites and 1.32 times higher than that of polymer matrix. This experiment proves that the magnetic core–shell particles can be oriented by the external magnetic field, and this orientation structure can improve the dielectric properties of the composite. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT) nanoparticles were prepared by the sol–gel process followed by the hydrothermal method. The as-prepared PZT showed Pb(Zr0.52Ti0.48)O3 phase which was successfully incorporated into a polyvinylidene fluoride (PVDF) polymer matrix by a simple solvent casting method. The X-ray diffraction and field emission scanning electron microscopy (FESEM) results showed phase purity and formation of PZT nanoparticles composited along with α and β-phase PVDF polymer. The dielectric properties of PZT-PVDF nano-composites were evaluated in detail concerning different frequencies and it was observed that the dielectric constant and dielectric loss tangent increased with the PZT content. Mixing a moderate amount (0.5 wt%) of PZT into the PVDF matrix not only enhances the dielectric constant of the matrix but also encourages the transformation of the PVDF crystal from α-phase into β-phase. These effects can improve the dielectric constant, conductivity, and dielectric loss with good dielectric stability. Room temperature dielectric measurement of 0.5PZT-PVDF composites at 30 kHz gives 10–11 times higher electrical conductivity compared to neat PVDF. Besides, it is found that dielectric permittivity values at the lower frequency are affected by space charges while in the higher frequencies the influence of relaxation effect in the materials was observed. It was realized that 0.5PZT-PVDF polymer matrix can withstand optimum temperature and the DSC thermogram exhibited good endothermic peak. Our experimental results reveal that the dielectric parameters like real, imaginary modulus and dielectric loss have a strong frequency reliance. [ABSTRACT FROM AUTHOR]