Search

The influence of density and shape of hollow silicas (silica hollow tubes (SHT) or hollow glass microspheres (HGM)) on dielectric and heat‐resisting characteristics of poly(ether ketone ketone) (PEKK)/SHT and PEKK/HGM films was systematically investigated. The dielectric characteristics of PEKK/SHT or PEKK/HGM films decrease to a minimum, as their SHT or HGM contents approach 8 or 20 wt%, respectively, and the minimum dielectric constant (εr) and dielectric loss (tan δ) of PEKK/SHT or PEKK/HGM films decrease visibly with decreasing SHT densities. By filling with 0.46 g cm−3 mean density of SHT or HGM fillers, the minimum εr and tan δ of PEKK/SHT films are somewhat smaller than those of PEKK/HGM films. The linear coefficient of thermal expansion (LCTE) values of PEKK/SHT or PEKK/HGM films reduce and their onset degradation temperature values increase gradually with increasing SHT and HGM contents. Low εr/tan δ (2.11/0.0022 and 2.2/0.0027 at 1 MHz), LCTE (35.5 × 10−6 and 31.2 × 10−6 °C−1) and excellent heat‐resisting properties favorable for sixth generation (6G) ultrarapid communication are realized for appropriately prepared PEKK/SHT and PEKK/HGM substrate films. The free‐volume‐hole characteristics of PEKK/HGM or PEKK/SHT films approach a maximum as SHT or HGM contents reach an optimum value of 8 or 20 wt%, respectively. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In this work, Gadolinium (Gd3+) substituted Co–Cu–Cr (CCC) SFs with the chemical formula Co 0.5 Cu 0.5 Cr 0.5 Gd x Fe 1.5-x O 4 (x = 0.00, 0.05, 0.10, 0.15, and 0.20) were synthesized via the self-combustion process. The single-phase matrix of the Gd3+ substituted CCC SFs was verified using X-ray diffraction (XRD). The crystallite size (D) of Gd3+ doped CCC SFs was reduced from 51.20 nm to 36.27 nm with increasing Gd3+ doping. The addition of Gd3+ in the CCC SFs lattice enhanced specific surface area (S) from 22.11 cm2/g to 28.57 cm2/g. The energy bandgap (E g) was increased from 4.83 eV to 5.40 eV and revealed an inverse relation with crystallite size. The tangent loss (tan δ), dielectric loss (ε ″), dielectric constant (ε ′), and ac conductivity (σ a c ) of Gd3+ doped CCC SFs exhibit frequency-dependent behaviour. The behaviour of these dielectric properties has been analyzed using both Koop's theory and the Maxwell-Wagner model. Moreover, it was found that the ε ′ was enhanced, while σ a c and tan δ w as reduced with the doping of Gd3+ in CCC SFs. The saturation magnetization and microwave operating frequency were increased with the doping of Gd3+ in CCC SFs. Because of their diverse dielectric and magnetic properties, the Gd3+ doped CCC SFs have considerable potential for different applications, including microwave absorption materials, switching high-frequency devices, and microwave frequency-operating devices. [ABSTRACT FROM AUTHOR]

This work demonstrates the fabrication, characterization, and energy storage capacity of high calcium-doped strontium titanate thick films (Sr0.60Ca0.40TiO3) for the first time. The thick films were fabricated using the screen-printing technique and densified using uniaxial pressing. The effect of densification on the structural, morphological, and surface chemical compositional of the materials was studied. The densified thick film revealed a notable frequency stability of dielectric permittivity (ε′) ≈ 198 with a low dielectric loss tangent (tanδ) in the order of 10− 3 between 100 Hz and 1 MHz and was characterized by slim P-E loops signifying its paraelectric nature. A high energy recovery density (Ue) of 4.1 J/cm3 and a high energy efficiency of 96% were simultaneously reached. [ABSTRACT FROM AUTHOR]

The samples including Li 0.1 Co 0.8 Fe 2. 1 O 4 (LCFO) spinel ferrite (SF) and LCFO SF/graphene oxide (GO = 10 wt%, 15 wt%, and 20 wt%) nanocomposite were fabricated via the self-ignition route by following the bath ultra-sonication method. Their structural, morphological, and compositional properties were analyzed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy-dispersive X-ray (EDX) spectroscopy, respectively. Moreover, the dielectric and magnetic properties at 300 K were studied using an impedance analyzer (IA) meter and vibrating sample magnetometer (VSM), respectively. All LCFO SF and GO-based LCFO nanocomposites exhibited a pure spinel matrix. The crystallite size was increased by the GO addition in the LCFO SF sample. The morphological analysis showed the non-uniform distribution of particles. The dielectric constant and loss exhibited behaviour consistent with Maxwell-Wagner interfacial polarization. The low tangent loss was observed at high frequency and ac conductivity analysis was increased with increasing the GO content. A slight enhancement in saturation magnetization was observed at 300 K with the addition of GO in LCFO SF. Hence, doping with GO offers a means to tune the dielectric, and magnetic response of the LCFO SF sample and is the best candidate for potential high-frequency application. [Display omitted] • The LCFO SF and LCFO/GO nanocomposites were prepared via the self-ignition route with an ultra-sonication technique. • The crystallite size was increased from 30 nm to 54 nm. • FTIR analysis along with XRD analysis also confirmed the spinel matrix. • SEM and TEM micrographs indicated the non-uniform distribution and agglomeration with the increasing GO. • The increase in GO leads to an improvement in the dielectric response. • The saturation magnetization was increased with the addition of GO. • The combination of LCFO SF with GO enhanced the dielectric, and magnetic properties, offering a candidate for high-frequency applications. [ABSTRACT FROM AUTHOR]

The effect of boron doping on dielectric properties was examined using β-SrTa2O6:xEu3+ (x = 1.5 mol%, 3 mol%, 5 mol%, 10 mol%), β-SrTa2O6:xEu3+, yB3+ (x = 1.5 mol%, 3 mol%, 5 mol%, 10 mol%, y = 10 mol%) and BaTa2O6:xEu3+, yB3+ (x = 10 mol%, y = 0 mol%, 5 mol%, 15 mol%, 30 mol%, 50 mol%, 70 mol%, 100 mol%) tungsten bronze ceramics produced by the solid-state reaction method. X-ray diffraction (XRD) results of all the β-SrTa2O6 and BaTa2O6 samples showed that they retained a single-phase structure. In scanning electron microscopy (SEM) examinations, the presence of boron promoted grain growth and agglomeration in the β-SrTa2O6 grains, while the increased boron concentration led to grain elongation in addition to grain growth in the BaTa2O6 grains. The dielectric results for the β-SrTa2O6:xEu3+ and β-SrTa2O6:xEu3+, yB3+ series showed that increased Eu3+ caused a decrease in the dielectric constant (ε′) and dielectric loss (tan δ), whereas the increasing B3+ presence for the BaTa2O6:xEu3+, yB3+ series led to an increase in the dielectric constant and a decrease in dielectric loss. The increase in tetragonality for BaTa2O6:xEu3+, yB3+ ceramics was correlated with a higher ferroelectric Curie temperature. [ABSTRACT FROM AUTHOR]

Forsterite was synthesized with MgCO 3 and SiO 2 powders using a solid-state method at 1200–1300°C. The ceramic specimen with the highest forsterite phase content was sintered with the ZrO 2 sintering aid at mass fractions of 0.5, 1.0, and 1.5 wt% at 1400°C for 4 h. The dielectric constant and loss tangent were also measured via the waveguide method at 8–12 GHz. The formation of enstatite and cristobalite was minimized through precise synthesis temperature control. Phase measurement by the Rietveld method showed that specimen F28 contained more than 99.8% forsterite. It was found that ZrO 2 reduced the pore volume percent and increased the density even at low mass fractions. A liquid phase on the grain boundaries was demonstrated. The solid ceramic specimen F28-15Z showed a dielectric constant of 6.5 and high quality factor of 189000. [ABSTRACT FROM AUTHOR]

The advancement of crystalline growth and characterization tools allows us to investigate novel nonlinear optical substances suitable for photonic applications. Bis-(4-aminopyridine)-zinc(II) acetate (B4AZA), a metal–organic crystal was produced in this study using the slow evaporation procedure at room temperature. Analytical studies such as X-ray crystallography, Fourier transform infrared (FT-IR), UV–visible (UV–Vis), fluorescence, second harmonic generation (SHG), and dielectric tests were used to characterize the as-grown B4AZA crystals. According to the solubility data, the sample has a positive temperature coefficient of solubility. The crystallographic findings show that the B4AZA crystallized in a monoclinic structure with the P21/n space group. Molecular vibrations and functional groups in the substance were determined using the FT-IR technique. The UV–Vis absorbance and transmittance spectra have shown the wide transparency and minimum absorbance of the B4AZA in the near UV and entire visible regions of the electromagnetic spectrum. The bandgap of the B4AZA has been calculated using the Tauc relation and found to be 4.32 eV. The fluorescence spectra have shown a prominent emission peak at 584 nm with an excitation wavelength of 280 nm. The larger Stokes shift found in the fluorescence spectra is advantageous for practical applications. The SHG study revealed that the powdered B4AZA samples generated a second harmonic output. The dielectric test revealed frequency-dependent changes in the dielectric constant and loss factor. Both the dielectric constant and the loss factor decrease exponentially as frequency increases, reaching low values at higher frequencies. The experimental results illustrate the suitability of the B4AZA crystals for photonic applications. [ABSTRACT FROM AUTHOR]

The dielectric constant (ε′) and dielectric loss (ε″) of pure honey (PH) and honey-water mixtures have been measured over 20 Hz − 20 GHz frequency range, at 26 °C using a precision LCR meter and a Vector Network Analyzer. It has been observed that as water proportion in honey increases, ε′ and ε″ increases over the given frequency range. The dielectric relaxation peak of ε″ for honey-water mixture in the microwave frequency range shifts towards relaxation peak of water as amount of water in honey increases. The normalized ε′/ε′PH ratio is found to increase with increase in water content in Honey, reaching up to 1000 over 20 Hz to 2 kHz. In frequency range from 500 MHz to 5 GHz, ε′/ε′PH ratio approaches a value of 10 times at 750 mg/g. Over 20 Hz to 2 MHz frequency range, ε″/ε″PH ratio approaches 100 times that of PH, but over frequency range from 200 MHz to 600 MHz the ratio ε″/ε″PH is found to decrease anomalously with increase in water content in PH. Further, over the frequency range from 8.2 GHz to 20 GHz the ε″/ε″PH ratio continuously increases with increase in water content. [ABSTRACT FROM AUTHOR]

Sol–gel synthesis method was employed to fabricate nanocomposites of (Dy, Hf) co-doped 0.8BiFeO3–0.2CaTiO3 (Bi0.75Dy0.05Fe0.80O3–Ca0.20Ti0.18Hf0.02O3/BDyFO–CTHfO composite). Structural analysis, utilizing X-ray diffraction and Rietveld refinement with Fullprof software, confirmed a rhombohedral structure with space group R3c and an orthorhombic structure with Pnma space group. Particle size determined through Scherrer's formula was ~15 nm. FESEM studies revealed irregular and slightly dense inhomogeneous grains. Dielectric permittivity (ε) and tangent loss (tan δ) were investigated as functions of frequency from 100 Hz to 1 MHz at different temperatures ranging from 303 to 663 K. The dielectric dispersion behaviour was attributed to Maxwell–Wagner-type polarization, with a notable anomaly in dielectric permittivity observed near the magnetic phase transition temperature (TN ~ 643 K) of BiFeO3. Frequency-dependent ac conductivity exhibited low-frequency dispersion following Jonscher's power law. Presence of ferroelectricity was confirmed by the polarization–electric field (PE) loop. Magneto-dielectric characteristics were assessed in a frequency range of 100 Hz–1 MHz under a magnetic field of 0–2 Tesla. Impedance spectroscopy highlighted electrical properties, distinguishing grain and grain boundary contributions via Nyquist plot with respect to the magnetic field. The BDyFO–CTHfO composite demonstrated significant absorption and ~ 25% transmittance in the visible spectrum. The material exhibited a band gap (Eg) of 1.97 eV, suggesting potential applications in ultrafast optoelectronic devices. [ABSTRACT FROM AUTHOR]

This study presents the characterization and optimization of BaTiO3-doped ZnO-based varistors for electrical and electronic applications. The varistors were prepared using a conventional ceramic procedure and were sintered at a temperature of 1,000 °C with different concentrations of BaTiO3 (0 and 3 mol%) added to the Bi2O3/ZnO-based varistor composition (99.5 mol% ZnO and 0.5 mol% Bi2O3). The results showed that the addition of BaTiO3 led to the formation of various oxides and solid solutions, such as Bi12TiO20, BaTiO3, and (Bi2O3)0.80 (BaO)0.20. The dielectric constant and grain size decreased with increasing BaTiO3 content, while the non-linearity coefficient, electric fields (Eb) increased, and dielectric loss (Tand) decreased. The optimized varistor contains 2 mol% BaTiO3 and an electric field of 148.08 V/mm, which are superior to those of the BaTiO3/Bi2O3/ZnO-based varistor. During this study, we were able to observe that a slight addition of BaTiO3 will increase the breakdown voltage and the coefficient of nonlinearity and this will allow us to develop lowdimensional varistors and install them in the high-voltage domain. [ABSTRACT FROM AUTHOR]

The lower valence compensation of YMn1-xCuxO3 (x = 0.00, 0.05, and 0.10) is prepared by the solid-state reaction, and the effects of divalent cation Cu-doping on the construction and magnetic and dielectric attributes of multiferroic YMnO3 are systemically researched. Powder X-ray diffraction shows YMn1-xCuxO3 has a single-phase hexagonal construction with a P63cm space group as the parent YMnO3, and lattice parameters decrease systematically as Cu concentration increases. Using the scanning electric microscope, structure morphologies analysis shows that the mean grain size varies between 1.90 and 2.20 μm as Cu content increases. YMn1-xCuxO3 magnetization increases as Cu doping concentration increases, and the antiferromagnetic transition temperature declines from 71 K for x = 0.00 to 58 K for x = 0.10. The valence distributions of Mn ions conduce to the modified magnetic attributes. Due to Cu substitution, the dielectric loss and dielectric constant decline as frequency increases from 400 to 700 K, showing representative relaxation behaviors. Indeed, that is a thermally activated process. In addition, the peak of the dielectric loss complies with the Arrhenius law. The relaxation correlates to the dipole effect regarding carrier hopping between Mn3+ and Mn4+, and also correlates to oxygen vacancies generated by Mn2+. [ABSTRACT FROM AUTHOR]

Polymer-ceramic nanocomposite films using double perovskite ceramic phase offer promising prospects for developing multifunctional flexible films in general and energy storage system in specific. The manganese and iron-based double perovskite is emerging as potential system for various functional applications. In the present attempt, we explore the application of poly (vinylidene fluoride) (PVDF):Nd2MnFeO6 (NMFO) composite films as an energy storage system. The NMFO was synthesized by sol–gel combustion method, and its structure is confirmed by X-ray diffraction (XRD) analysis, which demonstrates the formation of a single-phase monoclinic system with the space group P21/n. Detailed structural information is extracted through Rietveld refinement of XRD data using full-prof software. To create flexible nanocomposite films, various volume percentages (10%, 20%, 30%, 40%, and 50%) of NMFO ceramic nanoparticles are incorporated as fillers in the PVDF polymer matrix using the solution casting method. The structural properties of the developed nanocomposite films are investigated using XRD and FTIR studies, while microstructural features are investigated through SEM analysis. Dielectric properties of nanocomposite thin film are studied at different frequency ranges (1–200 kHz) using a LCR meter. Furthermore, the ferroelectric behavior of the nanocomposite thin film was systematically examined using a PE Loop Tracer. Remarkably, the nanocomposite thin film containing approximately 30 wt% of NMFO exhibited significantly higher dielectric permittivity, low dielectric loss, and increased remanent polarization, coercivity, and spontaneous polarization at room temperature. These findings highlight the potential of this nanocomposite film as a flexible energy storage system. [ABSTRACT FROM AUTHOR]

Citric acid solution and solid state are paired to prepare Sm-doped Sr1 − xBaxBi2Ta2O9 (x = 0, 0.05) ceramics in a way that byproducts are not released. XRD technique demonstrated that the compounds maintained orthorhombic structure, whereas lattice parameters analysis showed that dopants induce distortion of the orthorhombic unit cell. SEM revealed that plate-shaped dense ceramics can be fabricated. The electrical study sheds light on the influence of motif on carrier transport in Sr1 − xBaxBi2Ta2O9 (x = 0, 0.05) ceramics. A partial Sm/Ba occupational disorder in lattice structure induces a diffuse phase transition. Compared to pure samples, the effect of samarium on dielectric properties was markedly revealed, reducing dielectric loss and enhancing the dielectric constant at room temperature. The electoral study carried out at higher temperatures, suggests that the mobility of the charge carrier is mainly due to a hopping mechanism according to the correlated barrier hopping (CBH) model fitted to hopping conduction. Through the electrical modulus model, the mobility of the charge carriers in the system is involved in a long-short-range hopping approach. Sm-dopant content leads to an upshift in the barrier energy of the AC, DC, and CBH conductivity models. Thus, when Sm atoms go up to 1.37 at% (x = 0.1) may hamper the free movement of charge carriers, leading to lower tanδ values. [ABSTRACT FROM AUTHOR]

A transparent composite sample containing BaTiO3 was synthesized by using the melting quenching method. The presence of a glassy phase in this composite sample was detected through XRD analysis, and this was further confirmed by DSC study. TEM and SAED analyses provided evidence that the BaTiO3 nanoparticles/clusters are embedded within the borate glass matrix, establishing the composite nature of this sample. FTIR spectrum of the present sample revealed that the glass matrix is composed of two structural groups (BO3 with NBO's, and BO4), along with the distinct groups for BaTiO3. XPS spectra of the present composite sample indicated the presence of more than one type of boron, barium, titanium and oxygen. DSC and dielectric studies of the present composite sample revealed the presence of the phase transition temperature (Tc). Dielectric constant (ɛr) and dielectric loss (tan δ) curves of the present composite sample displayed an anomaly peak in the vicinity of TC. The optical transmission spectrum of the present composite sample exhibit two transmission bands of Ti3+ (3d1) ions in tetragonal distorted sites. At room temperature, the present transparent composite sample exhibited double hysteresis loops for BaTiO3 at low electric fields. The results obtained can be used for the development of lead-free ferroelectric material. [ABSTRACT FROM AUTHOR]

Frequency‐dependent dielectric constant and dielectric loss of pristine and green‐synthesized (using Tabernaemontana divaricata flower extract) ZnO nanoparticles (NPs) are studied at different temperatures. Below 1 kHz frequency and at temperatures above 100 °C, ZnO NPs have giant dielectric constant values (≈3 × 104). At lower frequencies and at/below 100 °C, the nature of temperature dependence of dielectric constant for pristine and green‐synthesized ZnO NPs are reversed, and this anomalous temperature dependence is correlated with the in‐plane and out‐of‐plane thermal expansions of ZnO. A temperature‐dependent poly‐dispersive relaxation mechanism in ZnO has been observed. The electrical conduction mechanism is found to be significantly modulated by the use of flower extract. The electric modulus study suggests similar mechanism of electrical conduction and dielectric polarization followed in these materials. A plausible growth mechanism of the ZnO NPs in presence of the flower extract is explored. Variations in the dielectric constant, dielectric loss, conductivity, and polarization mechanisms of the ZnO NPs are understood as signatures of the capping effect of the phytochemicals present in the flower extract on the crystal growth and formation of grain boundaries. [ABSTRACT FROM AUTHOR]

In this paper, we have mainly reported the preliminary structural analysis and the frequency–temperature dependence of the dielectric and electrical properties of ceramic technology-fabricated Sn-modified bismuth titanate with a chemical composition of Bi4Ti2.9Sn0.1O12 electro-ceramic at room temperature. The compound is synthesized in a single-phase orthorhombic structure, as shown by the analysis of the X-ray diffraction pattern and data at room temperature. Detailed studies of dielectric and electrical properties in a wide temperature range (25 to 400°C) at different frequencies ranging from 1 to 1000 kHz have provided many important properties of the prepared sample. The dielectric constant and tangent loss at temperature 400°C and frequency 1 kHz are found to be 3 × 103 and 1.6, respectively. It was possible to calculate the contributions of the grains and grain boundaries to the overall resistance and capacitance of the synthesized material using Nyquist plots. The types of conduction mechanisms have been studied from an ac-conductivity study of the material. The J–E characteristics of the prepared sample which have slopes closer to 1, support the Ohmic behaviour. The study of the electric field and frequency dependence of electric polarization through hysteresis loops has confirmed the ferroelectric behaviour of the studied material at room temperature. Some experimental data obtained here suggest that the material may be useful as an electronic component in electronic industries. [ABSTRACT FROM AUTHOR]

Polymer/conductive carbon particle composites have been studied for use in energy storage capacitors to achieve a strong dielectric response. Nevertheless, the robust percolation of carbon particles results in a large dielectric loss. Focusing on the high dielectric response and low energy dissipation, in this study, a combination of worm-like expanded graphite (e-graphite) and alpha-alumina particles was used to obtain polymer-based composites. Instead of graphite, a worm-like e-graphite possessing a large specific surface area can enhance the polymer/graphite interface polarization. Alpha-alumina particles displaying high insulation can restrain the percolation of e-graphite and induce the branching of electric trees. Two composite systems: polymer/e-graphite and polymer/e-graphite/alumina, were fabricated. Compared to the ultrahigh dielectric permittivity, and dielectric loss of the binary composites, a high dielectric constant and an ultra-low dielectric loss were obtained for the ternary composites. The ternary composite with 4 wt.% e-graphite and 6 wt.% alumina exhibited a high dielectric permittivity of ~ 189 and a low dielectric loss of ~ 0.047 at 1 kHz. This study may enable the low-cost preparation of dielectrics. [ABSTRACT FROM AUTHOR]

In the present study, a series of lead-free ceramics (1−x)BaFe0.5Nb0.5O3-xBiCu0.75W0.25O3 (BFN-xBCW) were synthesized using a solid-state reaction method. The crystallization of all samples in the cubic structure with Pm 3 ¯ m space group was confirmed by X-ray diffraction (XRD) results. The calculated and observed patterns exhibited good agreement after Rietveld refinement. SEM analysis showed that the average grain size of the samples ranged from 0.89 to 1.20 µm. The sample (1−x)BFN-xBCW (x = 0.01) has the smallest grain size (0.89 µm). Detailed studies of dielectric properties as a function of temperature and frequency, have provided several interesting properties. As a function of temperature, a dielectric step at low temperature and a dielectric peak at high temperature were observed. The temperature stability was improved by incorporating 1% BCW (x = 0.01). Combining BCW with BFN successfully reduced the dielectric loss. The smallest tan δ value was obtained for x = 0.02 with a moderate ε'. As a function of frequency, two steps were observed. The step observed at higher frequencies and lower temperatures is attributed to the Debye-type relaxation process in the grains, while the step observed at low frequency and high temperature range is attributed to the non-Debye Maxwell–Wagner (M-W) polarization effect. [ABSTRACT FROM AUTHOR]

Silica hollow tube (SHT) nanofillers were fine distributed in poly(ether ketone ketone) (PEKK) to serve decently as sixth generation (6G) substrate films. Distinctly lower dielectric and thermal expansion characteristics were detected for all PEKKaxSHTy film sequence filled with proper amounts of SHT nanofillers. The dielectric characteristics detected for all PEKKaxSHTy film sequence diminished to a minimum, as SHT loads came near an optimal value of 8wt%. The LCTE evaluated for each PEKKaxSHTy film sequence reduced distinctly with increasing SHT loads. Suitable dielectric constant (εr) (2.26 at 1 MHz), and/or dielectric loss (tan δ) (0.0027 at 1 MHz) and/or Linear coefficient of thermal expansion (LCTE) (30.5 × 10−6/ °C) for 6G rapid-speed communication were detected for PEKKP700092SHT8 substrate film having 8wt% load of SHT nanofillers. Meanwhile, the beginning degradation temperatures estimated for all PEKKaxSHTy film sequence increased distinctly with increasing SHT loads. All free-volume-cavity characteristics estimated for all PEKKaxSHTy film sequence approached a highest value, as SHT loads came near an optimal value of 8wt%. Distinctly lower εr and tan δ were detected for PEKKa and PEKKaxSHTy having higher free-volume-cavity characteristics. Possible interpretations for the distinctly diminished dielectric and/or heat-resistant characteristics acquired for PEKKaxSHTy films are presented. [ABSTRACT FROM AUTHOR]

The present study describes the green synthesis of hematite (α-Fe2O3) nanomaterials using the Tabernaemontana divaricata flower extract as a reducing/capping/stabilizing agent and the changes observed in the structural, optical, magnetic and dielectric properties of the product with respect to the pristine counterpart. Powder XRD study showed that use of the extract in green synthesis produces hematite nanomaterials of reduced size, whereas FE-SEM, HRTEM and EDX studies revealed the morphology, particle size distribution, crystallinity as well as the elemental contributions. FT-IR spectroscopy detected the different functional groups and metal-ion bonding present in the synthesized nanomaterials. Raman study observed the seven Raman active (two A1g and five Eg) modes with different intensities. From the UV–Vis study, different electronic transitions occurred in the hematite nanomaterials were identified, and the direct (1.90–1.97 eV) and indirect (1.21–1.46 eV) energy band gap values were estimated. Two photoluminescence peaks (one in visible and the other in near infrared region) detected in the spectra indicated the presence of various defect levels in the hematite nanoparticles within the energy band gap. Magnetic measurements exhibited the Morin transition to occur in these materials, while Mössbauer spectra successfully showed the magnetic contribution of the iron atoms occupying the core and the surface parts of the nanoparticles. Use of the extract in green synthesis produced hematite nanomaterials with extremely high dielectric constant (~ 105) and significantly lower dielectric loss at low frequency and at room temperature when compared to the pristine one which signify their huge application potential. The results obtained from the characterization studies made on the pristine and green synthesized hematite nanomaterials revealed that the green synthesis of hematite nanoparticles using Tabernaemontana divaricata flower extract can efficiently modify their optical, magnetic and dielectric properties. Thus, using commercially cheap starting materials and extracts made from naturally available plant parts, materials having huge application potentials (like microwave and energy storage appliances) can be synthesized at low-cost by the simple green synthesis approach. [ABSTRACT FROM AUTHOR]

The CaSn0.95Mn0.05O3 (CSMO) was produced by using the sol-gel wet chemical process. The structural composition was examined using an X-ray diffraction (XRD) pattern, and the presence of an orthorhombic structure with the space group Pbnm was confirmed by Rietveld refinement. At different temperatures between 300 K and 773 K, the dielectric permittivity (ε), tangent losses (tanδ), and electrical conductivity of CSMO has been measured as a function of frequency from 100 Hz to 1 MHz.Dielectric permittivity (ε) is found to be independent of temperature up to 400K and very low tangent loss. Jonscher's power law in the material's frequency-dependent ac conductivity shows its semiconductor nature. Optical band gap of CSMO was observed by using UV-vis.absorption spectra. The optical band gap of CSMO, which was determined using Tauc plot measurements to be 2.42 eV, suggests that the sample is a semiconductor. The Arrhenius model is employed to perform an analysis of the dc conductivity of the material concerning both frequency and temperature. As a result of its semiconductivity, stable dielectric constant, and low tangent loss, CSMO is a suitable material for thermally stable capacitors, semiconductor devices, UV filter and UV detectors. [ABSTRACT FROM AUTHOR]

The CaSn0.95Mn0.05O3 (CSMO) was produced by using the sol-gel wet chemical process. The structural composition was examined using an X-ray diffraction (XRD) pattern, and the presence of an orthorhombic structure with the space group Pbnm was confirmed by Rietveld refinement. At different temperatures between 300 K and 773 K, the dielectric permittivity (ε), tangent losses (tanδ), and electrical conductivity of CSMO has been measured as a function of frequency from 100 Hz to 1 MHz.Dielectric permittivity (ε) is found to be independent of temperature up to 400K and very low tangent loss. Jonscher's power law in the material's frequency-dependent ac conductivity shows its semiconductor nature. Optical band gap of CSMO was observed by using UV-vis.absorption spectra. The optical band gap of CSMO, which was determined using Tauc plot measurements to be 2.42 eV, suggests that the sample is a semiconductor. The Arrhenius model is employed to perform an analysis of the dc conductivity of the material concerning both frequency and temperature. As a result of its semiconductivity, stable dielectric constant, and low tangent loss, CSMO is a suitable material for thermally stable capacitors, semiconductor devices, UV filter and UV detectors. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) nanoparticles have been used at different concentrations (1–5 wt%) to prepare fluoroelastomer (FKM) nanocomposites. The physico-mechanical features of FKM nanocomposites exhibit an increase in tensile strength, modulus, hardness and elongation at break decrease with increasing concentration of GO nanoparticles. This is due to the good distribution of GO in FKM rubber. The effect of GO concentration on dielectric performances which includes dielectric loss tangent (tan δ), real impedance, imaginary impedance and electrical conductivity were studied as a function of frequency range 10−2 –105 Hz. The intensity of tan δ peak of FKM nanocomposites has a gradual decrease with frequency as well as their peaks also shifts toward lower frequency region. Variation in spectra of real impedance reveal decreasing behavior with frequency and imaginary impedance characterizes the properties like diminished peak intensity for GO/FKM nanocomposites. The Nyquist plots show good semicircles that exhibit polarity with a single relaxation time. The extent of the GO concentration has a significant impact on the dielectric permittivity of the nanocomposites. Using the percolation theory, it has been determined how frequency affects electrical conductivity. The percolation phenomenon has been discussed using electrical conductivity of GO/FKM nanocomposites and found at 4 wt% GO concentration. [ABSTRACT FROM AUTHOR]

Zero dimensional graphene quantum dots (GQDs) exhibit fascinating chemical and physical properties discovered by Pan et al., in 2010, due to the quantum confinement and edge effect. GQDs have been synthesized by hydrothermal treatment method from graphite powder as low cost, easy process, and large amount with high production yield. The functional groups of GQDs on the surface sites of carbon atoms have been studied through Fourier transform infrared spectroscopy (FTIR) analysis. X-ray diffraction (XRD) pattern of GQDs shows the broad diffraction at 2 θ = 24.47 ° with 0.36 nm an interlayer distance confirming the formation of the GQDs. Raman analysis reveals that GQDs show both D and G bands mostly the armchair edges. UV–visible spectra show absorption peak at 287 and 330 nm credited to π → π * and n → π * transitions due to the presence of conjugated carbon–carbon bonds and carbonyl groups. The particle size of GQDs is found below 5 nm from high- resolution transmission electron microscopy (HR-TEM) image. Scanning electron microscopy shows the surface morphology of GQDs are crumpled and aggregated thin sheets. Dielectric properties of synthesized GQDs have been studied in the range frequency between 0.01 and 105 Hz at different temperatures (25, 50, 75, and 100 °C). The dielectric relaxation mechanism is explained in the framework of dielectric loss tangent (tanδ), permittivity and electrical conductivity. The dielectric loss tangent increases with frequency and maximum peak decreases with frequency at all different temperatures due to present of polar groups in GQDs. Dielectric permittivity decreases with frequency at all different temperatures due to charge orientation and rotation of dipole moments. The electrical conductivity increases with frequency at all different temperature due to the GQDs is highly conductive nature. So synthesized GQDs can be used in electrical and electronic materials. [ABSTRACT FROM AUTHOR]

The nano-graphite (NG) and acid modified nano-graphite (ANG) have been synthesized from graphite powder via mixture of strong acid (sulphuric acid and nitric acid) respectively by a soft chemistry route involving microwave, ultrasonic method and characterized by high-resolution electron microscopy (HR-TEM), scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), clearly demonstrated the successful synthesis of acid modified NG. SEM images confirmed the surface morphology of NG, and ANG and HR-TEM study shows the nanoparticles size of NG and ANG. FTIR data confirmed the presence of acid functional groups on the surface of synthesized NG powder. XRD data of NG and ANG shows that 2θ is at 26.43° and 0.336 nm is an interlayer distance (d). NG and ANG pellets have been prepared for their dielectric analysis with frequency for different thickness. The dielectric loss tangent (tanδ) spectra show relaxation peak with frequency and peak shifts due to presence of polar groups in the ANG. The capacitance values of NG and ANG decrease with frequency and increase with thicknesses due to the capacitive nature of nanoparticles. The dielectric permittivity decreases with frequency and increases with thickness due to the charge orientation and dipole moment change of functional groups of synthesized NG, and ANG. The electrical conductivity of NG and ANG nanoparticles increases with frequency and thickness of NG and ANG pellets due to the conductive nature. Electrical conductivity and dielectric permittivity of NG and ANG are found to highly rely on thickness, according to the dielectric evaluation. [ABSTRACT FROM AUTHOR]

This study aims to comprehensively evaluate the impact of Sm 2 O 3 doping on PZT ceramics, specifically focusing on the phase structure, microstructure, and dielectric characteristics of Pb 1-x Sm x [(Zr 0.52 Ti 0.48) 0.9 (Mo 1/3 In 2/3) 0.05 (Zn 1/3 Sb 2/3) 0.05 ]O 3 samples namely PSZT-PSMI-PSZS ceramics. Sm 2 O 3 was doped at site A within the range of 0.00 ≤ x ≤ 0.08 using the solid-state reaction method and sintering at 1150 °C. The examination of the results revealed that the samples exhibited a perovskite structure, along with a secondary phase, with increasing intensity of the said phase as Sm content increased. XRD, Rietveld refinement, and Raman spectroscopy analysis indicate a decrease in the rhombohedral phase ratio (R) and an increase in the tetrahedral phase ratio (T) with higher Sm content. Microscopic examination using SEM demonstrates variations in microstructure, with the highest density and grain size observed at a small increment of Sm content (x ≤ 0.02). Optimal electrical properties were achieved at x = 0.00, including a high dielectric constant (ε r = 8578), Curie temperature (T c) of 303 °C, and dielectric loss (tanδ) value of 0.34. Conductivity studies indicate a negative temperature coefficient of resistance (NTCR) for all samples. Additionally, the relationship between electrical characteristics and Sm 2 O 3 doping is discussed. This research provides valuable insights into the structural, microstructural, and electrical properties of PZT ceramics affected by Sm 2 O 3 doping. [ABSTRACT FROM AUTHOR]

In this paper, an unexplored solid solution (1-x)Bi(Cu1/2Ti1/2)O3-(x)PbTiO3 has been synthesized and characterized for its crystal structure, dielectric and ferroelectric properties aimed at a selected composition, i.e., 0.30 Bi(Cu1/2Ti1/2)O3-0.70PbTiO3. The paper unveils the different synthesis approaches to achieve pure-phase in Pb-based perovskite-structured materials that are prone to produce impurities during synthesis. The Rietveld refinement of the XRD pattern confirms a tetragonal crystal structure (P4mm) of the composition. The ferroelectric properties of the as-prepared composition are also discussed using P-E hysteresis and PUND characteristics. The composition shows a high Tc (480 °C) and low dielectric losses, making it suitable for high-temperature applications. [ABSTRACT FROM AUTHOR]

In this paper, an unexplored solid solution (1-x)Bi(Cu1/2Ti1/2)O3-(x)PbTiO3 has been synthesized and characterized for its crystal structure, dielectric and ferroelectric properties aimed at a selected composition, i.e., 0.30 Bi(Cu1/2Ti1/2)O3-0.70PbTiO3. The paper unveils the different synthesis approaches to achieve pure-phase in Pb-based perovskite-structured materials that are prone to produce impurities during synthesis. The Rietveld refinement of the XRD pattern confirms a tetragonal crystal structure (P4mm) of the composition. The ferroelectric properties of the as-prepared composition are also discussed using P-E hysteresis and PUND characteristics. The composition shows a high Tc (480 °C) and low dielectric losses, making it suitable for high-temperature applications. [ABSTRACT FROM AUTHOR]

Polymer-based dielectric composites are of great importance in advanced electronic industries and energy storage because of their high dielectric constant, good processability, low weight, and low dielectric loss. FDM (Fused Deposition Modeling) is a greatly accessible additive manufacturing technology, which has a number of applications in the fabrication of RF components, but the unavoidable porosity in FDM 3D-printed materials, which affects the dielectric properties of the materials, and the difficulty of large-scale fabrication of composites by FDM limit its application scope. This study's main focus is on how the matrix, filler, interface, and FDM 3D printing parameters influence the electrical properties of FDM-printed polymer-based dielectric composites. This review article starts with the fundamental theory of dielectrics. It is followed by a summary of the factors influencing dielectric properties in recent research developments, as well as a projection for the future development of FDM-prepared polymer-based dielectric composites. Finally, improving the comprehensive performance of dielectric composites is an important direction for future development. [ABSTRACT FROM AUTHOR]

In this work, 80-nm Bi3.15Nd0.85Ti3O12 thin films with different annealing temperature have been successfully fabricated on p-type silicon substrates by sol-gel method. The effect of annealing temperature on the microstructure, dielectric properties, and energy-storage performances of the thin films were investigated in detail. The prepared films at 750 °C had a layered perovskite structure with an excellent crystalline morphology, featuring a high dielectric constant of 43.8 and a low dielectric loss < 2% at 1 kHz, which lead the significantly improvement of breakdown strength to increase the energy storage properties. The maximum recoverable energy density of 4.3 J/cm3 with an efficiency of 70.7% under the electric field of 1.90 MV/cm has been obtained for the Bi3.15Nd0.85Ti3O12 film capacitors at 750 °C. These properties indicate that Bi3.15Nd0.85Ti3O12 system is a promising environmentally friendly lead-free ferroelectric. [ABSTRACT FROM AUTHOR]

(K0.48Na0.52)NbO3-0.03Bi0.5Na0.5ZrO3 (KNNS-0.03BNZ) ceramics were prepared doped with 3 mol% Bi0.5Na0.5ZrO3 (BNZ), and the effect of sintering temperature on dielectric and piezoelectric properties of KNNS-0.03BNZ was also investigated. KNNS-0.03BNZ ceramics at all sintering temperatures exhibit a single perovskite structure, and the change of sintering temperature has no significant effect on the phase composition of KNNS 0.03BNZ ceramics. The Raman shifts of the ν1 and ν5 vibration modes have irregular changes in all sintering temperature ranges, indicating that there are polycrystalline phases coexisting in this region. With the change of sintering temperature, Tc slightly shifts to the high temperature direction, and TR-T slightly shifts to the high temperature direction, dielectric constant εr continuously increases, while dielectric loss tanδ firstly decreasing and then increasing. Thanks to the presence of a small amount of liquid phase in the ceramics sintered at 1160 °C, piezoelectric coefficient d33 reaches 280 pC/N. [ABSTRACT FROM AUTHOR]

High-frequency nanocomposites have gained attention as electronic and telecommunication technologies. These nanocomposites consist of ferrite and a polyaniline matrix. Sol-gel technique was used to generate the ferrite nanomaterial, and in-situ synthesis was used to generate the polyaniline. The X-ray diffraction (XRD) analysis elucidated the existence of a single-phase structure comprising SrEr 0.04 Fe 1.96 O 4 ferrite particles dispersed throughout the polyaniline matrix. To counteract the amorphous nature of polyaniline, adding spinel ferrite to nanocomposites boosted their crystallite size (20 nm–56 nm). When ferrite was combined with polyaniline, the dielectric constants and dielectric loss (ε ′ , ε ″) were found to decrease as a function of frequency. The ferromagnetic characteristics of the manufactured composites were discovered through hysteresis loop analysis. Saturation Ms, remanence Mr, and coercivity Hc all increased with ferrite content. Direct current (dc) resistivity and activation energies of the composite sample enhanced with concentration of polyaniline in ferrites. Improvements in all the properties of nanocomposites (FP4) may be suitable candidates for high frequency applications. [ABSTRACT FROM AUTHOR]

This study reports the effects of gamma radiation on the AC electrical properties of epoxy nano-silica composite sheets with an average thickness of 3 mm. Epoxy reinforced with different nano-silica concentrations of 0, 5, 10, and 15 wt.%. The epoxy nano-silica composites were exposed to different gamma radiation dosages of 1, 3, and 5 kGy. The data were analyzed before and after gamma irradiation and the results showed that the AC electrical properties of the gamma-irradiated epoxy nano-silica composites varied from those of the non-irradiated samples. We found that there were significant changes in the impedance, dielectric constant, dielectric loss, and AC electrical conductivity values of the epoxy nano-silica composites after irradiation, and the AC electrical conductivity and dielectric constant values of the nano-silica composites were enhanced by exposing the samples to gamma radiation because more free electrons were released inside the epoxy nano-silica composites. The AC electrical properties, such as impedance, dielectric constant, dielectric loss, and electrical conductivity, of the epoxy nano-silica composites were studied and discussed before and after gamma radiation with different dosages. We found that these AC electrical properties marginally increased with increasing doses of gamma irradiation. [ABSTRACT FROM AUTHOR]

A major disadvantage of dielectric materials is their low energy density. In this study, we used a poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) matrix, polar ferrous titanate (FTO) nanofillers, and non-polar diamond nanofillers to prepare composite thin films with enhanced dielectric properties. Two types of nanocomposite films, namely, PVDF-HFP/FTO and PVDF-HFP/FTO/diamond, were fabricated and their electric properties were measured under the application of a low electric field. The binary composites exhibited a high dielectric constant and high dielectric loss, whereas the ternary composites exhibited a high dielectric constant and low dielectric loss. FTO, which has a high dielectric response and conductivity, interacts with the polymer, which has a low conductivity, to increase the dielectric constant of the ternary composites. The insulating diamond nanoparticles cause the leakage current to branch out, thereby reducing the dielectric loss. The optimal ternary composite consisted of 30 wt% FTO and 2 wt% diamond. It exhibited the most balanced dielectric properties (dielectric constant of ~ 40 and dielectric loss of ~ 0.4) and a low conductivity of ~ 7 × 10–7 S m–1 at 100 Hz. This work aims to facilitate the large-scale preparation of advanced polymer nanocomposites for applications in capacitors. [ABSTRACT FROM AUTHOR]

Tungsten doped Barium Titanate (BT) with composition BaW0.05Ti0.95O3 (BWT) were prepared by using ball milling technique for different hours (10 h, 20 h and 30 h). In the present paper, the microstructural, dielectric and impedance studies are discussed. The microstructural studies using XRD data reveals the formation of single phased tetragonal structure and perovskite structure. The dielectric properties of BT nanoceramics were significantly enhanced by the partial replacement of W (at B site) showing the diffuse phase transition at 80°C. Dielectric loss rises as the temperature rises. There is increase in charge carrier mobility which results in increased polarization and significant dielectric loss. Additionally, compared to the un-milled BWT ceramic sample, the 30 h milled had superior dielectric characteristics with high dielectric constant and reduced loss. The nature of the phase transition was confirmed by the Curie-Weiss law and the ferroelectric analysis was carried by well-established P-E loops. The impedance studies were carried out by plotting Nyquist plots. The ac conductivity plot follows Arrhenius relation and the calculated activation energy confirms the negative temperature coefficient of resistance (NTCR) behavior of the material. [ABSTRACT FROM AUTHOR]

This study aims to determine the effect of the sintering temperature of nanosilica on physical, mechanical, dielectric, and output voltage properties. The nanosilica particles used in this experiment were produced using the alkaline fusion method from natural sand. The green bodies were uniaxially formed with a pressure of 75 MPa and then were pressureless sintered at various temperatures of 1330, 1360, 1390, 1420, and 1450°C for 2 hours in an air atmosphere. The results of sintering showed that the highest bulk density and the relative density of 2.49 ± 0.03 g/cm3 and 94.03 ± 0.01% respectively were achieved at a sintering temperature of 1390°C. The XRD patterns of the sintered silica indicated phases of quartz, tridymite, and cristobalite, with the strongest peak corresponding to the cristobalite phase. The highest compressive strength and diametral tensile strength values of 17.23 ± 0.27 MPa and 6.06 ± 0.71 MPa respectively were obtained on specimens sintered at 1390°C. However, the highest values of the dielectric constant of 544.28, dielectric loss of 195.94, and output voltage of 1.58 mV were obtained at a sintering temperature of 1330°C. Various sintering temperatures do not significantly influence the characteristic of dielectric and output voltage of the sintered specimens. [ABSTRACT FROM AUTHOR]

In this paper, comparative studies of hydrophilic and hydrophobic mesoporous silica particles (MSPs) on the dielectric properties of their derivative polyester imide (PEI) composite membranes were investigated. A series of hydrophilic and hydrophobic MSPs were synthesized with the base-catalyzed sol-gel process of TEOS, MTMS, and APTES at a distinctive feeding ratio with a non-surfactant template of D-(-)-Fructose as the pore-forming agent. Subsequently, the MSPs were blended with the diamine of APAB, followed by introducing the dianhydride of TAHQ with mechanical stirring for 24 h. The obtained viscous solution was subsequently coated onto a copper foil, 36 μm in thickness, followed by performing thermal imidization at specifically programmed heating. The dielectric constant of the prepared membranes was found to show an obvious trend: PEI containing hydrophilic MSPs > PEI > PEI containing hydrophobic MSPs. Moreover, the higher the loading of hydrophilic MSPs, the higher the value of the dielectric constant and loss tangent. On the contrary, the higher the loading of hydrophobic MSPs, the lower the value of the dielectric constant with an almost unchanged loss tangent. [ABSTRACT FROM AUTHOR]

• P (VDF-HFP)/h-BN composites maintain outstanding frequency stability under 100 ℃ and 105 Hz, the loss is less than 0.08. • The energy storage efficiency of 1 vol% single-layer P(VDF-HFP)/h-BN composite is 3% higher than that of pure P(VDF-HFP). • The energy storage performance of 1 vol% and 01310 P(VDF-HFP)/h-BN composites are higher than that of the other structures. The increase in the electrical conductivity of polymer matrix composites at high temperature will result in the deterioration of capacitive properties. In this study, the coupling strategy involving wide band-gap h-BN nanosheets with favorable thermal conductivity and stability combined with electrospinning hot pressing process was proposed, and polyvinylidene fluoride-hexafluoropropylene copolymer (P (VDF-HFP)) based composites with single layer and progressive three-layer structure were designed. These films can maintain outstanding frequency stability under 100 ℃ and 105 Hz, and their dielectric loss are less than 0.08. The energy storage efficiency of 1 vol% single-layer P(VDF-HFP)/h-BN composite is 69 %, which is approximately 3 % higher than that of pure P(VDF-HFP). The energy storage value of 1 vol% single-layer P(VDF-HFP)/h-BN composite during the charging process is about 22.25 J/cm3, which is about 39 % higher than that of 3 vol% single-layer composite. The energy storage value of 01310 progressive three-layer P(VDF-HFP)/h-BN composite during the charging process is approximately 23 J/cm3, which is about 72 % greater than that of 31013 progressive three-layer composite. This work offers a perspective for enhancing the dielectric capability of P(VDF-HFP). [ABSTRACT FROM AUTHOR]

To fabricate magnetoelectric devices, magnetically switchable dielectric properties in functional multiferroic composites are a significant challenge. In this study, an attempt is made to synthesize multiferroic composite (1- x) Ni 0.5 Co 0.5 Fe 2 O 4 (NCFO) – x BaTiO 3 (BTO) (x = 0, 0.6, 0.8, 1) using a solid-state route with tunable magnetodielectric (MD) properties. The microstructure of the composite revealed a highly dense and closed-packed structure with a maximum relative density of 97 % for the x = 0.8. The X-ray photoelectron spectroscopy (XPS) analysis showed that oxygen vacancy is suppressed from 25.1 % to 19.6 %, with increased BTO concentration. The maximum saturation magnetization of 26 emu/g and 29 emu/g is observed for x = 0.6 at 303 K and 10 K, respectively. The magnetic irreversibility between zero field cooled-field cooled (ZFC-FC) curves exhibited the larger magneto anisotropy of the composite sample. The dielectric properties are significantly changed with the magnetic field, indicating the signature of a strong magnetoelectric effect. Interestingly, a broad transition at ∼ 150 K and ∼ 286 K is observed corresponding to the BTO, which is attributed to rhombohedral to orthorhombic and orthorhombic to tetragonal phase transitions, respectively. For the x = 0.8, the maximum dielectric constant of ∼ 811 with a minimum dielectric loss of 0.04 is observed at 1 MHz. For the same composition, the maximum MD of ∼ 0.7 % and ∼ 1.2 % is observed at 300 K and 200 K, respectively. In addition, the different contributions and prone causes (intrinsic and extrinsic origin) of MD are revealed using the Cole-Cole plot. The strong MD effect and low dielectric loss of these composites make them suitable for multifunctional device applications such as magnetic sensors, magnetoelectric random access memory (MERAM), etc. [Display omitted] • The multiferroic Ni 0.5 Co 0.5 Fe 2 O 4 – BaTiO 3 composite system has been investigated. • Two dielectric anomalies at ∼ 150 K and ∼ 286 K are observed. • The maximum MD of ∼ 0.7 % and 1.2 % at 300 K and 200 K is observed for NBC80. • The M s of 26 emu/g and 29 emu/g is observed for NBC60 at 303 K and 10 K. [ABSTRACT FROM AUTHOR]

In the industry of high-temperature sensors and actuators, materials capable of delivering high ferroelectric, dielectric, and specifically stable/high piezoelectric performances above 1000 °C are in demand. Hence, perovskite-like layered structured (PLS) have gained popularity due to their high Curie temperature (T C) and ferroelectric properties, but the low piezoelectric coefficient (d 33) at high temperature (>1000 °C) is the problem statement to be explored and improved. Herein this research, La 1.97 (LiCe) 0.03 Ti 2 O 7 :xwt%MnO 2 (LLCTO:xMn) with x = 0–0.3 ceramic series has been explored to study the ultra-high structural, ferroelectric, electric, dielectric, and piezoelectric properties. Among all compositions, LLCTO:0.2Mn ceramic has demonstrated ultra-high performances with remnant polarization (P r) of ∼1.84 μC/cm2, piezoelectric co-efficient (d 33) of 9 pC/N, resistivity of ∼1011 Ω.cm, relative dielectric constant (ɛ r) of 46, and minor dielectric loss (tanδ) of 0.17 which are much improved compared to pure La 2 Ti 2 O 7 (LTO) and pristine La 1.97 (LiCe) 0.03 Ti 2 O 7 (LLCTO) ceramics. The LLCTO:0.2Mn ceramic has exhibited the high T C of 1415 °C. Moreover, thermally stable multifunctional performances are measured where LLCTO:0.2Mn ceramic has demonstrated a high d 33 of ∼8.5 pC/N at 1200 °C and resistivity of ∼2.4 × 107 Ω.cm even at 1000 °C, which are much better than the earlier reports. From the analysis, LLCTO:0.2Mn ceramic has demonstrated the potential to be utilized in high-temperature (>1000 °C) piezoelectric devices. • La 1.97 (LiCe) 0.03 Ti 2 O 7 :xwt%MnO 2 (LLCTO:xMn) with x=0–0.3 ceramic series has been explored to study the ultra-high ferroelectric, electric, dielectric and piezoelectric properties. • LLCTO:0.2Mn ceramic has demonstrated remnant polarization (P r) of ∼1.84 μC/cm2, piezoelectric co-efficient (d 33) of 9 pC/N, resistivity of ∼1011 Ω.cm. • LLCTO:0.2Mn ceramic has exhibited the high Curie temperature of 1415 °C. • LLCTO:0.2Mn ceramic has demonstrated the high d 33 of ∼8.5 pC/N at 1200 °C and resistivity of ∼2.4 × 107 Ω.cm even at 1000 °C, which are much better than the earlier reports. [ABSTRACT FROM AUTHOR]

Future measurements of the millimeter-wavelength sky require a low-loss super-conducting microstrip, typically made from niobium and silicon nitride, coupling the antenna to detectors. We propose a simple device for characterizing these low-loss microstrips at 150 GHz. In our device we illuminate an antenna with a thermal source and compare the measured power at 150 GHz transmitted down microstrips of different lengths. The power measurement is made using microwave kinetic inductance detectors (MKIDs) fabricated directly onto the microstrip dielectric, and comparing the measured response provides a direct measurement of the microstrip loss. Our proposed structure provides a simple device (4 layers and a DRIE etch) for characterizing the dielectric loss of various microstrip materials and substrates. We present initial results using these devices. We demonstrate that the millimeter-wavelength loss of microstrip lines, a few tens of millimeters long, can be measured using a practical aluminum MKID with a black body source at a few tens of Kelvin. [ABSTRACT FROM AUTHOR]

Polymer/conductor composites are used in energy storage capacitors; however, they exhibit high interface leakage currents, causing low breakdown strength. Here, a ternary-blend strategy was used to synthesize polyvinyl chloride (PVC)/titanium carbide transition-metal carbide two-dimensional nanolayered material (Ti2C MXene)/diamond composites using solution casting. The PVC matrix exhibited low polarity and high insulation, while the Ti2C MXene and diamond fillers exhibited high conductivities and ultrahigh insulation properties, respectively. Overall, the PVC/Ti2C/diamond ternary composites exhibited better electrical properties than the PVC/Ti2C binary composites. In the ternary composites, PVC/Ti2C interface polarization caused high dielectric constants, while low leakage currents induced by diamond caused low dielectric losses and high breakdown strength. The optimum-composition (12 wt.% Ti2C and 4 wt.% diamond) ternary composite exhibited a high dielectric constant (~153 at 100 Hz), low dielectric loss (~0.14 at 100 Hz), low conductivity (~1.4 × 10−6 S m−1 at 100 Hz), and high breakdown strength (~312 MV m−1 under a direct current field). This study indicates a synergistic effect between Ti2C MXene and diamond in the composite dielectrics, and could guide the fabrication of dielectric films for capacitors. [ABSTRACT FROM AUTHOR]

The development of polymer nanocomposites with superior dielectric performances is critical for flexible capacitive energy storage applications. However, the common approach to fabricate polymer composites with high-dielectric-constant ceramics as fillers always bring about exaggerate dielectric losses, hence low energy density and energy efficiency of polymer composites. In this work, BNNSs/AgNPs nanohybrids, where Ag nanoparticles were deposited on the surface of boron nitride nanosheets (BNNSs), are employed as fillers for poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) based nanocomposites. The contributions by enhanced interface polarisation and the internal barrier layer capacitor (IBLC) effect generated by the uniform distribution of conductive Ag nanoparticles on the insulative BNNSs, result in a large increase in dielectric constant and electric displacement meanwhile simultaneously suppressed dielectric losses. The BNNSs/AgNPs/PVDF-HFP nanocomposites exhibit much higher energy density and energy efficiency than the pristine PVDF-HFP and the BNNSs/PVDF-HFP composites counterparts, being great potential for dielectric energy storage applications. [ABSTRACT FROM AUTHOR]

A series of rare earth neodymium (Nd3+) doped Ni–Zn–Bi nanoferrites of composition Ni 0.5 Zn 0.5 Bi 0.04 Nd x Fe 1.96-x O 4 (x = 0.002, 0.004, 0.006, 0.008, 0.010) has been synthesized by a citrate precursor technique. Structural, morphological, electrical, and dielectric characterizations have been undertaken. X-ray diffraction pattern confirmed cubic spinel ferrite structure of the prepared nanoferrites with crystallite size in the range of 25–30 nm. From the Hall-Williamson graphs, a tensile strain has been noticed due to an expansion of lattice with an increase in Nd composition. The octahedral and tetrahedral modes of vibrations were confirmed by Fourier Transform Infrared spectroscopy (FTIR) peaks at wavenumber 590 cm−1and 403 cm−1. The D.C. resistivity performance of the nanoferrites was found in the range of 1010 Ω cm calculated from the current-voltage plot. Dielectric studies were undertaken at room temperature in the frequency range from 10 kHz to 10 MHz. The dielectric behaviour of the prepared samples reveals that the real part increases from 4.85 to 13.67 and imaginary values rise from 0.49 to 4.46 at 105 Hz. The dielectric loss tangent value decreases from 0.34 to 0.15 with the change in Nd ion concentration. The AC conductivity rises from 2.18 × 10−6 to 2.39 × 10−5 S/cm at 105 Hz. These lower values of loss tangent in Nd doped Ni–Zn–Bi nanoferrites materials are useful in deflection yoke and high-frequency applications. [Display omitted] • Average crystallite size was found in the range 25–30 nm. • Enormous DC resistivity values in the range 2.89 × 109–1.60 × 1010 Ω-cm were observed. • The real part of dielectric constant was found to be in the range 4.85–13.67. • Imaginary part of dielectric constant was found in the range 0.49–4.46. • AC conductivity was observed in the range 2.18 × 10−6 - 2.39 × 10−5S/cm at 105 Hz frequency. [ABSTRACT FROM AUTHOR]

In this research, citron peel biochar and opuntia‐cladode fibers (OCF) reinforced epoxy composites were fabricated and characterized for mechanical, wear, and electrical properties. The biochar was prepared from the waste peels of citron edible fruit whereas the opuntia fiber was from the cladode of the opuntia plant. The laminates were fabricated by hand layup process and evaluated in accordance with the ASTM standards. The results revealed that the mechanical properties such as tensile strength, flexural strength, impact toughness, hardness and adhesion strength were increased by 36.2%, 30.6%, 91.3%, 1.1%, and 5.3% for composite designation EC containing 30 vol% of OCF. Similarly, the addition of citron biochar of 2 vol% increased the load bearing and dielectric properties. However, the inclusion of 30 vol% of OCF on composite designation EC the sp. wear rate recorded 0.018 mm3/Nm. Similarly, the lowest coefficient of friction and sp. wear rate is observed to be 0.42 and 0.008 mm3/Nm for the composite with 2.0 vol% biochar. The ECO4 composite designation represented a maximum dielectric constant and dielectric loss of about 7.4 and 1.1, respectively. The SEM fractography demonstrates that the silane‐treatment strengthened the fiber‐matrix interface and improved the interlocking mechanism. Such mechanically robust, wear‐resistant improved and electrically conductive composites could be utilized in applications such as industrial sectors, spacecraft, automobile parts, packaging industries, and electrical appliances. [ABSTRACT FROM AUTHOR]

The nanocomposites of doped Polyaniline (PANI) with ZnO-TiO2 nanoparticles have been prepared by in-situ polymerization method. The structural properties of synthesized PANI and PANI/ZnO-TiO2 were studied by X-ray diffraction (XRD) analysis. XRD pattern show that PANI is intercalated into the layers of ZnO-TiO2 successfully and thus the degree of crystallinity increases due to crystalline nature of ZnO-TiO2. FTIR analysis indicated that there is a strong interaction between ZnO-TiO2 nanoparticles and PANI. Electronic properties (Dielectric and Conductivity) of PANI and PANI/ZnO-TiO2 nanocomposite have been investigated between frequency ranges from 20Hz to 01MHz, higher dielectric constants and dielectric losses of PANI/ZnO-TiO2 nanocomposites were found. As the content of ZnO-TiO2 increased, the dielectric constant and loss also increased. The value of dielectric constant for all samples is very high at low frequency but decreases with increase in frequency. Synthesis of PANI/ZnO-TiO2 nanocomposite materials with a large dielectric constant is promising for charge storage devices applications. [ABSTRACT FROM AUTHOR]

Ferroelectric materials have been widely used in fields such as capacitors and transducers. A lead-free ferroelectric single crystal (Ba 0.77 Ca 0.23 TiO 3) was grown by an improved Czochralski method. The composition of the crystal was verified by quantitative analysis. The basic electrical properties such as ferroelectric and dielectric of the Ba 0.77 Ca 0.23 TiO 3 crystals along different orientations have been investigated. A complete set of dielectric, piezoelectric and elastic parameters were characterized by the dynamic resonance method. BCT crystal along the <001> orientation has the largest piezoelectric constants. Its d 33 , d 31 and d 15 were 204 pC/N, −58.3 pC/N and 156.7 pC/N, respectively, and the coupling coefficients are k 33 , k 31 , k 15 , k t were 71%, 30%, 45%, 50%, respectively. These values are better than barium titanate (BT) crystal. At the same time, BCT crystal also has a higher dielectric constant and lower dielectric loss like barium titanate. [ABSTRACT FROM AUTHOR]

High‐temperature performance is critical to the dielectric polymer capacitors used in environment electronic and high‐power applications. Here, the authors report a composite comprising polyimide (PI) dielectric polymers blended with high‐insulation magnesium oxide (MgO) nano‐filler that exhibits high breakdown strength, wide temperature range, and low dielectric loss. However, most dielectric polymers possess excellent energy storage properties at room temperature and cannot be used at high temperatures above 100 °C. Polyimide dielectric nanocomposites prepared by in situ polymerization, which are composed of easily prepared MgO fillers, have different morphologies, such as nanoparticles (0D), nanowires (1D), and nanoplates (2D). The experimental results show that the insulation behavior and breakdown strength of polymer composites are closely related to the morphology of MgO fillers, and the rationality of this conclusion is further proved by finite‐element simulation results. The polymer composites containing ultra‐low content (0.5 vol%) MgO nanosheets produce an ultra‐high capacitance performance, that is, the discharge energy density is 4.78 J cm−3 at 150 °C, which is significantly better than the most reported dielectric polymers and nanocomposites. [ABSTRACT FROM AUTHOR]

In situ chemical polymerization method was used to synthesize the polyaniline (PANI) and polyaniline cadmium oxide (PANI-CdO) nanocomposites. The morphology and structure of pure PANI and PANI-CdO nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, whereas electrical properties were studied by dielectric, electric modulus and a.c conductivity. Various dopant-to-polymer ratios were used to investigate their effect on the characteristics of the synthesized samples. The SEM images exhibited granular as well as flaky structures of PANI and PANI-CdO nanocomposites. The XRD patterns revealed that pure PANI exhibits amorphous nature, while PANI-CdO nanocomposites exhibit polycrystalline nature. The crystallinity and intensity of (XRD) peaks of composite are enhanced by increasing CdO contents. The dielectric measurements show a decrease in dielectric constant, dielectric loss and a decrease in tangent loss with the increase in frequency and nearly constant values at higher frequencies, while the values of dielectric properties increase with the rise in temperature and doping concentration. The electric field modulus was used to analyze the relaxation behavior of the synthesized samples and found to be increased with frequency and decreased with the temperature and CdO concentration. The a.c conductivity was observed to increase with the increase in frequency and temperature for PANI and PANI-CdO composites. The changing behavior of the frequency exponent (S) at various temperatures was analyzed to observe different conduction mechanisms, and a correlated barrier hopping model (CBH) was found to be observed in PANI-CdO composites as well as in pure PANI. The Log a.c conductivity decreases versus the inverse of temperature and with increase in frequency that confirms that the hopping mechanism is the dominant charge transport mechanism. [ABSTRACT FROM AUTHOR]