Search

Poly(vinylidene fluoride) (PVDF), Barium Titanate (BaTiO3) and Montmorillonite (MMT) nanoclay based polymer nanocomposite (PNCs) were synthesized using a solution casting technique by encapsulating various loadings of BaTiO3 and MMT in PVDF matrix. The completely dispersed and highly flexible PVDF/BaTiO3/MMT nanocomposite films which were subjected to different characterization studies. The structural and morphological analysis of the synthesized nanocomposite films has been done using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). BaTiO3 and MMT reinforcement in the polymer matrix results in structural modifications of the PNCs. Thermogravimetric analysis (TGA) were employed to assess the thermal characteristics of PVDF/BaTiO3/MMT PNCs. The dielectric properties such as dielectric constant (ϵ), dielectric loss (tan δ), and AC conductivity (σac) of nanocomposite films were also examined as functions of frequency (50 Hz to 10 MHz) and temperature (30 °C to 150 °C). The highest ϵ was obtained at low frequency at higher temperatures for all the nanocomposite films. These findings imply that the PVDF/BaTiO3/MMT nanocomposites can be an effective material for energy storage applications. [ABSTRACT FROM AUTHOR]

This study investigates the dielectric properties, including dielectric constant (ɛ′), dielectric loss (ɛ″), tangent delta (tan δ), and AC conductivity (σac), of PVA/Y2O3 polymer nanocomposites (PNCs). The dielectric behavior of the PNCs was examined as a function of frequency and temperature. The results revealed that the addition of Y2O3 nanoparticles to the PVA matrix influenced the dielectric properties of the composites. In contrast to pure PVA, the PVA/Y2O3 PNCs with a 15 wt% Y2O3 loading exhibited high values of ɛ′, ɛ″, tan δ and σac are 647.49, 1607.48, 9.70 and 1.024 × 10−5, respectively, at low frequency and at particular temperature. Furthermore, the electrical properties of PVA/Y2O3 PNCs were also investigated using the Cole-Cole plots. These plots provide valuable insights into the complex impedance behavior and allow for comprehensive understanding of the electrical response of the nanocomposites. [ABSTRACT FROM AUTHOR]

The interaction of stearic acid with non-polar benzene along polar co-solvent (amyl alcohol) is revealed in the present study. The dielectric nature of complex mixture examined in the frequency regime of 10 MHz to 30 GHz over a various temperature and concentration using time domain reflectometry(TDR). Dielectric parameters (static dielectric constant, dielectric loss, relaxation time, dielectric permittivity) were estimated from the obtained complex spectra. The excess dielectric values validate the molecular interaction between the solute and solvents. The obtained dielectric and relaxation parameter reveals the fluctuating electrostatic type interaction among the complex mixture. Thermal parameters are determined from the obtained relaxation time, in which the negative Gibb's free energy indicates the formation of high ordered complex. The FT-IR spectrums and their assignments confirm the molecular interaction between the mixture. [ABSTRACT FROM AUTHOR]

The solution-based casting method fabricates the free-standing pure PVDF-TrFE, PVDF-TrFE-Nafion blended films and tests them for structural, morphological, and microwave studies. The X-ray diffraction pattern and FTIR spectrum confirmed the formation of the ferroelectric β-phase of PVDF-TrFE. The surface morphology of blended films is studied by scanning electron microscope (SEM), and noticeable changes in the morphological features are observed in the blended films resulting from the differences in the nucleation process in these films. Then using the open-ended coaxial probe method, the complex permittivity measurements were carried out over a large frequency range, from 0.5 GHz to 50 GHz. These results were verified with the Transmission-Reflection method using a rectangular waveguide in the X-band and Ku-band frequency range. The microwave absorption properties of the blends are also studied in the same frequency range. The stability of the dielectric properties and low microwave absorption indicates that the blending of PVDF-TrFE with Nafion results in a new potential material for high frequency flexible capacitor applications. [ABSTRACT FROM AUTHOR]

Cobalt disulfide (CoS2) is a highly sophisticated metal chalcogenide that has garnered significant attention due to its distinctive properties such as its electrical, optical, catalytic, and magnetic capabilities and potential for use in a range of applications. In this work, pure CoS2 nanoparticles were synthesized using the economical and facile hydrothermal method. The X-Ray diffraction (XRD) method was used to characterize the synthesized sample, confirming that it has a cubic crystal structure with space group P a −3. The Debye-Scherrer's formula was implemented to determine the average crystallite size of nanoparticles and found to be 24.24 nm. Through the use of Field Emission Scanning Electron Microscopy (FESEM), the morphology and effective grain size of the obtained sample was determined. FTIR spectrophotometry was used to examine the vibrational stretching of the various bonds in CoS2. UV-Vis spectroscopy is employed to measure the optical property of the sample. The optical bandgap calculated from the Tauc Plot is around 1.90 eV reflecting the presence of photovoltaic properties in the sample. The change in dielectric permittivity and loss have been observed for the sample in the frequency range of 100 Hz to 10KHz at different temperatures between 303K and 423K. The frequency-dependent electrical conductivity of CoS2 is also explained. The observations revealed the presence of unique electrical and structural properties in the synthesized sample. [ABSTRACT FROM AUTHOR]

We report the structure, microstructure, dielectric, transport, and optical properties of the CaMn0.94Ce0.06O3 ceramic synthesized by the solid-state reaction method. Analysis of the X-ray diffraction (XRD) pattern of the sample adopts an orthorhombic crystal symmetry. A study of scanning electron microscope (SEM) micrograph shows the homogeneous distribution of the well-grown grains over the entire surface of the sample. The well-defined and distinct grain boundaries surrounding the compact grains may be a possible reason for a better conductivity mechanism in the sample. The study of the energy dispersive x-ray (EDX) spectrum provides information about the formation of high-purity samples and also confirms the presence of Ca, Mn, Ce and O in both weight and atomic percentages. The agglomeration rate during the sintering process may be a possible reason for a better dielectric and conductivity mechanism. Fourier-transform infrared spectroscopy (FTIR) study strongly supports the presence of all constituent element's atomic vibration bands. The study of the UV visible spectra provides the idea of semiconducting nature and bandgap energy of 4.89 eV. At a low range of frequency, the presence of the Maxwell-Winger type of dielectric dispersion is confirmed. Dielectric properties were investigated, including conductivity, dielectric constant, dielectric loss, and complex modulus. According to impedance analysis, primarily the charge carriers' long-range movement controls the conduction process. The semiconducting nature of the sample is confirmed by analysis of the Cole-Cole plots. [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]

Na0.875Ba0.125Nb0.875Ti0.125O3 (NNBT) and Na0.875Ba0.11Bi0.01Nb0.875Ti0.11Sn0.0112O3 synthesized by solid-state technique exhibit P4bm symmetry. Dielectric-relaxations for NNBT show a transition to an antiferroelectric state below 449 °C (TC) with a prominent fall in the dielectric constant and the dielectric loss, like parent NaNbO3. Below 175 °C (TF) Ba, Ti-doping induced frequency-independent dielectric peak marks the ferroelectric phase. With 1.5% Bi, Sn-doping in NNBT, the grain size and the density of the ceramic increase. Bi, Sn-doped NNBT exhibits dielectric transitions at TC and a diffused TF but with reduced conductivity. The doped NNBT system presents a high electrostrictive coefficient of ∼0.06 m4/C2. [ABSTRACT FROM AUTHOR]

Lead-free K0.47Na0.47Li0.06NbO3 added with different oxides such as ZnO, Na2SiO3, Bi2O3, NiO, and CoO were prepared with conventional two steps sintering ceramic method where the samples were sintered at 1050 °C(5 min) and 950 °C(4h). The phase structures and crystallite sizes were studied using X-ray diffraction analysis. A dispersive behavior is observed when dielectric constant and dielectric loss were studied with variation in frequency in the range from 20 Hz to 5 MHz at room temperature. It is seen that addition of oxides improved the dielectric properties. The a. c. conductivity and impedance characteristics for the samples were also measured for a wide range of frequencies using an impedance analyzer. The Nyquist impedance plot for these samples studied for the conduction mechanism. The results were analyzed and presented in the paper. [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]

In this report, the proposed compound (Ba0.95Zn0.05)(Ti0.95Sn0.05Se0.05)O3 is synthesized by mixed oxide route for the extensive study of the dielectric and electrical properties. The crystallization, symmetry, structure (tetragonal), space group (P4mm), and lattice parameters were confirmed by an X-ray diffraction study. The dielectric and electrical properties in a wide range of temperatures and frequencies of this particular composition deduce various interesting properties on high dielectric permittivity, low tangent loss, relaxation mechanism, non-Debye type conduction, and negative temperature coefficient of resistance. From the frequency and temperature dependence, dielectric loss shows a very low loss factor (<0.06) at low temperatures (<250 °C). Nyquist plots discuss the contribution of grain and grain boundary by fitting it with the help of the software ZSimpWin. The PE loop measurement showed that the corresponding hysteresis had main parameters for (Ba0.95Zn0.05)(Ti0.95Sn0.05Se0.05)O3 compound, remnant polarization (Pr = 0.28 µC/cm2) and coercive field (Ec = 1.35 kV/cm). All the above characteristics conclude that it may be applicable in electronic device industries. [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]

Antiferroelectric properties of copper formate tetrahydrate (CFT) crystal having phase transition temperature at were investigated theoretically. CFT have a layer-type structure in which layers of are sandwiched between the layers of copper formate in the lattice plane. By considering modified two sublattice pseudospin lattice coupled mode model Hamiltonian and double-time temperature-dependent Green function method for antiferroelectric copper formate tetrahydrate (CFT) crystal, the phase transition properties of crystal have been studied. Expressions are derived for soft mode frequency, dielectric constant and loss tangent for considered crystal. Model values are fitted in the derived expressions and the dependence of the above properties on temperature have been calculated. Theoretically obtained results are compared with experimental data and show similarities between them. Dielectric constant as a function of temperature shows a behaviour of the first-order transition with a large discontinuity at the transition point. These properties can be employed in a wide range of applications including memory devices, solar cells, biosensors and photovoltaic devices. [ABSTRACT FROM AUTHOR]

In this report, a complex barium titanate ceramic oxide of the form BaBi1.6Fe0.4TiO6 was prepared by the solid-state casting process. More Bi3+ percentage was selected to boost the dielectric and ferroelectric effects, while lowering the Fe3+ content could minimize the leakage current and consequently, the dielectric loss (tanδ). The X-ray diffraction (XRD) data suggests an establishment of monoclinic distortion (P21/c) of smaller mean crystallite size (∼40 nm) using the Debye-Scherrer formula. The compound exhibits dielectric values, such as ɛr ∼ 771, and relatively low loss, tanδ ∼ 0.017 at the ambient experimental conditions. Thus, the material can be incorporated into different electronic devices where higher dielectric constant and lower losses are essential, for example, multi-layered ceramic capacitors, transmission lines, and gate dielectrics. The AC-conductivity essence of the compound follows Jonscher's power law as well as Arrhenius relation. The PE hysteresis loop was traced at different conditions with a function of the incident electric field in the ambient atmospheric conditions. The outcome of this study revealed that the material has remanent polarization hence suggesting a ferroelectric effect with less hysteresis loss; therefore, it could be useful in memory storage devices. [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]

The well-known lead-based complex-double perovskite [A(BIBII)O3] material is lead iron niobate, or Pb(Fe1/2Nb1/2)O3. The effect of the liquid phase of borosilicate glass SiO2-B2O3 (BS) on the sinterability and dielectric behaviors of PFN is comprehensively explored in the current study. The PFN-BS-glass powder was synthesized by sol-gel. XRD is used to validate the crystalline structure of PFN as it is synthesized, PFN-BS-glass, and the amorphous nature of BS-glass. The SEM was used to analyses microstructure. PFN and PFN-BS green pellets were sintered under various sintering circumstances. The shape, compactness, dielectric properties, and magnetic behavior of PFN are discovered to be significantly influenced by the liquid phase sintering by BS-glass in PFN for the application high electrical resistivity material having low dissipation and low sintering temperature in multilayer ceramic capacitor. [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 order to realize the preparation of environmentally friendly piezoelectric ceramic coatings on the surface of metallic materials, sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT) ceramic coatings were prepared by supersonic plasma spraying. The surface morphology, cross-sectional morphology, phase structure, and elemental valence variations of the BNT coating were examined, as well as the dielectric and ferroelectric properties of the BNT coating. The results show that the coating has a good quality and a single perovskite structure. The dielectric constant was stable at about 425 and the dielectric loss was stable at about 0.06 when the test frequency reached 200 kHz. The coating exhibits good hysteresis lines under different applied electric fields. When the applied electric field was 40 kV/cm, the remnant polarization value of the prepared coating was 11.47 mC/cm². It can be seen that the BNT piezoelectric coating prepared by supersonic plasma spraying has good ferroelectric and dielectric properties, which lays a solid foundation for in-situ monitoring of environmentally friendly lead-free BNT piezoelectric coating. [ABSTRACT FROM AUTHOR]

By using a compression technique and a pelletizer, a Tellurium (Te) doped Bismuth Antimony (BiSb) sample in the form of pellet has been formed. Stoichiometric proportions of the materials (Bi, Sb, and Te) were calculated for the manufacture of pellets Bi2Sb(3-x):Tex (X = 0.1, 0.2, and 0.3). A precision LCR meter was used to measure the dielectric characteristics of Bi2Sb(3-x):Tex (X = 0.1, 0.2 and 0.3) pellets (BULK) in the frequency range of 20 Hz to 2 MHz at room temperature. Using Primary collected data, Dielectric loss, Dielectric constant, AC conductivity, and Real & Imaginary Electric modulus have been studied. All of these characteristics have been used to look at various ways that dielectric spectroscopy works. [ABSTRACT FROM AUTHOR]

In the work presented, the distinctive features of temperature behavior of dielectric permittivity ε, dielectric loss tangent tanδ and pyroelectric coefficient γ of classical ferroelectric KDP and crystals of its family, which have a network of strong OH...O hydrogen bonds, are discussed. Particular attention is focused on the evidence of quantum-chemical interactions in network of hydrogen bonds in the matrix of heavy nuclei. [ABSTRACT FROM AUTHOR]

Meta-structures based on periodic ferroelectric inhomogeneities in a dielectric matrix were implemented, which demonstrated tunability at a relatively low effective dielectric permittivity and low microwave losses. Glass-ceramic composite consisting of low melting glass and barium-strontium titanate was successfully incorporated into the periodic holes of dielectric matrix to form tunable metamaterial structure. The studied composite samples showed a relative dielectric permittivity of 18 with a dielectric loss level of 0.02 at a frequency of 2 GHz. The tunability of the entire structure under the applied electric field of 2 V/μm was 4%, which is a promising result for microwave tunable applications. [ABSTRACT FROM AUTHOR]

Zinc substituted magnesium ferrite with the compositional formula Mg1-xZnxFe2O4 (where x = 0.05, 0.10, 0.15, 0.20, 0.25) was synthesized using auto-combustion method. The ash obtained was calcined in microwave furnace at 550 °C for 30 min. The calcined powder was further annealed at 600 °C in the furnace. The structural, dielectric and magnetic properties were studied using XRD, LCR meter and vibrating sample magnetometer (VSM) for all the samples. XRD pattern confirmed the formation of the spinel cubic phase of magnesium ferrite. Lattice constants and density were determined from the Rietveld analysis of the XRD pattern. The crystallite size of all the samples was calculated. Presence of Fe-O bond in all the samples was confirmed by FTIR spectra. Dielectric properties such as dielectric constant and dielectric loss of all the samples were studied as a function of frequency. Both the quantities show dispersion with frequency. Dielectric constant and ac conductivity were found to be minimum when the concentration of Zn2+ is x = 0.15 while dielectric loss is maximum at this concentration. The VSM measurement showed that the saturation magnetization increased with the Zn2+ concentration up to x = 0.20. Electric polarizations of the samples were studied using P-E hysteresis loop. It was found that electric polarization decreased with the increasing concentration of Zn2+ up to x = 0.20. [ABSTRACT FROM AUTHOR]

The design of core-shell nanostructures is a potential approach to obtaining advanced dielectric nanocomposites. The frequency-dependent dielectric dispersion of gadolinium oxide (Gd2O3) encapsulated iron oxide (Fe2O3) core-shell nanoparticles (Fe2O3/Gd2O3 CSNPs) synthesized by the polyol route is investigated in the temperature range from 303 K to 553 K and in the frequency range from 42 Hz to 1.1 MHz. The phase formation of the materials is evaluated by X-ray diffraction analysis. Synthesized Fe2O3/Gd2O3 CSNPs have multi-core nature are found by Transmission electron microscopy (TEM). Relaxation time corresponding to dielectric loss is found to obey Arrhenius law with an activation energy of 0.26 eV. Dielectric relaxation is analyzed in the electric modulus formalism. The frequency-dependent conductivity spectra follow the Jonscher power law. [ABSTRACT FROM AUTHOR]

In this work, electrophysical features of the hard ferroelectric material PKP-35 are studied in a wide temperature range. Research object is a solid solution of lead zirconate-titanate (PZT) modified with some additives prepared by the conventional solid-state sintering method. The temperature dependences of the dielectric permittivity and dielectric losses in weak fields at frequencies of 1, 10, and 1000 Hz are obtained. The dielectric hysteresis loops at different temperatures are studied, the material features are revealed, the scope of application is determined. [ABSTRACT FROM AUTHOR]

A series of co-doped TiO2 ceramics named (Re0.5Nb0.5)0.005Ti0.995O2 (Re = La, Nd, Sm, Gd) were prepared by a solid-state reaction method. The microstructure, dielectric properties, and impedance spectra of (Re0.5Nb0.5)0.005Ti0.995O2 ceramics were systematically investigated in detail. The co-doped TiO2 with rutile structure ceramics possessing CP and low dielectric loss (<0.05) have been gotten. Low dielectric loss is attributed to enhancing grain boundary resistance and suppressing Maxwell–Wagner polarization This work maybe give us enlightenment about how to find low dielectric loss in co-doped TiO2 CP ceramics. [ABSTRACT FROM AUTHOR]

BST ceramics having a composition of Ba0.5Sr0.5Ti1-xSnxO3 (x = 0.03) was prepared following a high-temperature solid state reaction route with BaCO3, SrCO3, TiO2 and SnO2 as raw materials with a suitable stoichiometric ratio. The structural configuration was confirmed by XRD study, and the analysis revealed the structure to be of cubical type. SEM analysis was carried out to get a clear picture of grain and grain boundary. Dielectric and electrical characterization were conducted as a function of temperature as well as frequency ranging from 1kHz to 1 MHz. Complex and modulus spectroscopy analysis were carried out for deep understanding of the material behavior. Broadened dielectric loss peaks were obtained beyond a temperature of 250 °C indicating a non-Debye type relaxation behavior. relaxation peaks were observed at high temperature in a modulus plot, and the activation energies were calculated. The ac conduction phenomenon was found to be thermally activated and the frequency dependence followed Johnscher's Law. In the present study, a noticeable invariance nature of dielectric constant as well as flat and moderately low loss was observed at moderate temperatures and over a broad range of frequency making the material suitable for wide band application. [ABSTRACT FROM AUTHOR]

MnO2 added potassium sodium niobate (KNN) electroceramics were prepared by conventional double sintering ceramic route. The samples prepared have the compositional formula K0.5Na0.5NbO3+ (x)MnO2 where x = 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt% and 25 wt% is the amount of MnO2 added. The sintering of the samples was done using the microwave sintering technique. Pre-sintering was done at 850 °C for 20 min. Different sintering conditions may results in KNNs with varied properties. The studies of the structural properties of the prepared samples were done by X-ray diffraction (XRD) technique. It has been found that addition of MnO2 to KNNs and sintering at 1000 °C for 20 min and at 1050 °C for 10 min showed all the KNNs crystallization in tetragonal phase with nearly similar structural parameters. The electrical properties such as dielectric constant, dielectric loss and ac conductivity of the prepared samples were investigated using an impedance analyzer. The room temperature frequency variation of electrical properties showed a dispersive behavior for all the samples. The temperature variation of the dielectric properties showed an increase with the increase of temperature. The results of the various measurements are discussed in the paper. [ABSTRACT FROM AUTHOR]

In this attempt, dysprosium orthoferrite (DyFeO3) system is explored to investigate dielectric and magnetic ordering by modulating ferrites structure using Ni and Co-dopants in place of Fe. X-ray diffraction (XRD) study confirms the formation of single-phase materials; dopants effect on modifications of atomic-scale structural parameters like lattice parameters, Fe–O bond angles, and O–Fe–O bridging angles are extracted from Rietveld refinement. Microstructural features of sintered pellet of DFO system exhibits compacted sample having grain size around 100 nm. Frequency and temperature- dependent dielectric studies depict systematic decrease of dielectric constant and loss with temperature for almost all systems. Moreover, it is found that dielectric constant and loss increases by doping; for Co and Co-Ni co-dopants the effect is maximum. Temperature profile of dielectric constant of DFO system is found to exhibit relaxor behavior. A real part of impedance as a function of frequency indicates the values of Z′ coincides with high frequency, indicates reduction of barrier potentials at high frequency due to increase in AC-conductivity. Low-frequency resistance of doped systems is lower than DFO, except Co-doped DFO. Impedance loss spectra reveal relaxation behavior of the system, which is influenced by dopants. Relaxation frequency of Ni-doped and Ni-Co codoped DFO is found shifting toward higher frequency side than DFO and DCFO systems; indicate charge relaxation is faster in DNFO and DNCFO than DFO and DCFO systems. However, activation energy of charge relaxation is found lowest for DCFO system. Same trends are revealed from Modulus spectra. Conductivity mechanisms are revealed from a combined plot of M′′(f) and –Z′′(f) as a function of frequency and corresponding relaxation process. The results conclude that conductivity in DFO and Ni-doped DFO system is dominated by delocalized motion of charge carriers, while DCFO and DNCFO systems are due long-range motion. Magnetic hysteresis (M-H) curve shows the presence of a canted antiferromagnetic ordering matrix within weak Ferromagnetic components. Coercivity of doped DFO is greated than pure DFO. [ABSTRACT FROM AUTHOR]

Cesium dihydrogen phosphate crystal belongs to the potassium dihydrogen phosphate family of ferroelectrics. It is ferroelectric below 154 K. It shows a large isotope effect like other members of this family. We have modified two-sublattice pseudospin lattice coupled-mode model Hamiltonian by adding phonon anharmonic interactions, extra-spin lattice interactions, and direct spin-spin coupling as well as an electric field. By using modified model Hamiltonian, double-time thermal Green function method and following the Zubarev and Kubo formalism, we have derived theoretically expressions for soft mode frequency, dielectric constant, and loss tangent for cesium dihydrogen phosphate (CDP)-type ferroelectric crystals. By fitting model values of physical parameters, we have calculated thermal variations of normal mode frequency, dielectric constant, and dielectric tangent loss for CDP-crystal. We have compared our theoretical results with the experimental results of others. Our theoretical obtainedresults agree well with the experimental results of others. [ABSTRACT FROM AUTHOR]

In the present study, lanthanum oxide doped lithium borosilicate glasses were synthesized using standard melt-quenching technique. The synthesized glass materials were characterized by XRD, FTIR, density calculation, Electrical and dielectric properties measurements. The amorphous nature of the studied glasses was established through XRD spectra. FTIR spectra were used to investigate the different functional groups. Improvements in density and molar volume values were reported as the La2O3 content increased, it can be attributed to higher molecular weight of La2O3. Numerous other physical parameters such as lanthanum ion concentration (N), inter-nuclear distance (ri), polaron radius (rp), and field intensity (F) were determined using density values and are discussed in detail here. Electrical conductivity and dielectric measurements were carried out by impedance spectroscopy. The dynamical processes taking place in the glass system was studied by introducing conductivity and composition scaling. The dielectric constant (ε') and dielectric loss (Tan δ) with frequency at various temperatures are extensively explored. There is a fairly good correlation among the physical parameters, FTIR, electrical conductivity and dielectric properties for the glasses studied in the present work. [ABSTRACT FROM AUTHOR]

A series of nanocrystalline aluminum (Al3+) doped Lithium-Zinc ferrites (LZA) having general chemical formula Li0.5(1-x)ZnxFe2.5-yAly-0.5xO4 with x = 0.1 and y = 0.2 (S1C1), 0.4 (S1C2), 0.6 (S1C3) and 0.8 (S1C4) were synthesized by citrate sol-gel combustion method. The structural characterizations of the samples were carried out by X-Ray Diffraction (XRD) studies. Morphological investigations were performed using Scanning Electron and Transmission Electron Microscopies. XRD analysis confirmed the formation of single phase of the reported samples. All the samples crystallized in spinel cubic crystal structure with Fd-3m (227) space group. Crystallite size was estimated in the range of 19 nm to 21 nm using Scherrer formula. The variation of D.C. electrical conductivity as a function of temperature of as-prepared samples revealed the semiconducting nature. The dielectric constant (ε'), dielectric loss factor (ε") and the dielectric loss tangent (tan δ) were studied in the frequency range of 1 KHz to 1 MHz at room temperature by using LCR Meter. The values of dielectric constant, dielectric loss factor and dielectric loss tangent were found to decrease with addition of Al3+ content as well as with the increase in the frequency. The observed dielectric dispersion at lower frequency is attributed to Maxwell-Wagner type of interfacial polarization due to hopping of charge between Fe+2 and Fe+3. High value of resistivity (≈106 Ω-cm) and low value of dielectric constant and dielectric loss are the prime achievements of the present research work which make these investigated nanoferrites useful for the microwave devices. [ABSTRACT FROM AUTHOR]

In this work, 4CuO-TiO2-2Nb2O5 (CTN) composite oxide was added to ZnAl2O4 as sintering aid. XRD analysis revealed that trace amount of new phases formed in the ceramic samples with CTN, which might promote the low temperature sintering of ZnAl2O4 ceramics. The sample with 2 wt% CTN addition sintered at 1125 °C can achieve the highest thermal conductivity of 8.6 W/m·K and the lowest microwave dielectric loss of 3.59 × 10−4. The sintering temperature and thermal conductivity of ZnAl2O4 ceramics decreased while the dielectric constant and loss increased with the increase of the CNT contents. ZnAl2O4 ceramics can be sintered at a low temperature of 950 °C with the CTN content increasing to 10 wt%, which make it a potential material for the low temperature co-fired ceramics (LTCC) application. [ABSTRACT FROM AUTHOR]

A comparative study on dielectric properties was conducted for two series of ferroelectric composites prepared from Rochelle salt (RS) filled with a conductive filler of multiwalled carbon nanotubes in pristine (MWCNT) or oxidized (OMWCNT) forms. FTIR technique was utilized to evaluate characterization of functional groups in the composites. The obtained results indicated that the oxidization of MWCNT resulted in the significant increase in phase transition temperature of RS, while reduced dielectric loss and conductivity of composite samples in comparison with the use of pristine MWCNT. Besides, the influence of OMWCNT and MWCNT content on properties of RS was also considered. [ABSTRACT FROM AUTHOR]

Nanocomposites C:S-1:4 comprising cobalt ferrite (CoFe2O4), strontium ferrite (SrFe12O19) and C:B-1:4 containing cobalt ferrite (CoFe2O4), barium ferrite (BaFe12O19) were synthesized in weight ratios of 1:4 by chemical co-precipitation route with higher content corresponding to SrFe12O19 and BaFe12O19. Rietveld refinement was employed to confirm the presence of independent CoFe2O4, SrFe12O19 and BaFe12O19 phases. The average crystallite size of CoFe2O4 and SrFe12O19 in C:S-1:4 was observed as 20 nm and 56 nm which depicts an increase as compared to individual components. The observed lattice strain in C:S-1:4 was 0.05% and 0.03% for CoFe2O4 and SrFe12O19. In C:B-1:4, the value of strain was 0.06% and 0.04% for CoFe2O4 and BaFe12O19. Increased lattice strain was observed in the prepared composites. Increase in impedance for the prepared composites was observed from measurements performed in the frequency range 20 –106 Hz. Conduction mechanism was explained by overlapping large polaron tunneling model. Dielectric loss measurements for the prepared composites were observed to decrease establishing their usage in microwave applications. [ABSTRACT FROM AUTHOR]

Multiferroic composites xBaFe12O19-(1 − x)Na0.5Bi0.5TiO3 were synthesized. Rietveld analysis of XRD patterns of confirms the coexistence of hexagonal (P63/mmc) and rhombohedral (R3c) symmetry. SEM micrographs depict that the average grain size of composites decreases with increase in ferrite phase. The variations of dielectric constant (ε′) and dielectric loss (tanδ) were examined as a function of frequency and at different temperatures. ε′ and tanδ show the dispersion behavior at lower frequencies and become independent at higher frequencies. The magnetic assessment of these composites carried by analyzing M-H hysteresis loop reveals their hard magnetic behavior. [ABSTRACT FROM AUTHOR]

(1-x)Bi1/2Na1/2TiO3-xBa1/2Sr1/2TiO3-0.05KNaNbO3(BNT-BST-KNN, x = 0.01, 0.03,0.05,0.07) lead-free anti-ferroelectric ceramics were synthesized by a conventional solid-state. The effects of co-doping of Sr element and KNN group on phase structures, compositional distribution and electrical properties of BNT-BST-KNN ceramics were systematically investigated to further understand the mechanism of phase transition. It was found that the grain size decreased obviously, indicating that the addition of Sr element inhibited the grain growth. According to SEM and XRD analysis, the components of the samples obtained were all perovskite phase structure, and the coke free green stone was equal to other heterophases, indicating that K1+, Na1+, Nb4+ and Sr2+ ions successfully diffused into the crystal lattice of BiNaTiO3-BaTiO3 and formed a uniform solid solution. It shows that the doping of Sr element and KNN effectively promotes the transformation of trigonal phase to tetragonal phase. From the analysis results, the doping of Sr element and KNN effectively reduces the dielectric loss of the materials, and the dielectric property stability is greatly improved. [ABSTRACT FROM AUTHOR]

The present article addresses the old problem of correct estimation of ferroelectric parameters from the hysteresis loop. Experimental study of thin polycrystalline PZT films shows that the presence of leakage currents and dielectric losses causes distortion of the hysteresis loop and results in overestimated values of remanent polarization. The technique based on the measurement of the hysteresis at two frequencies (100, 200 or 300 Hz) is studied to obtain hysteresis loop cleared from dielectric losses. The modified Lorentz function was used for simulation of obtained hysteresis curves. This approach permits to obtain correct data generated from the dielectric hysteresis measurement. [ABSTRACT FROM AUTHOR]

The solid solution of (Ba5TbTi3V7O30)x(BiFeO3)1-x has been synthesized by solid-state reaction technique with different x values. XRD (X-Ray Diffractogram) study confirms the formation of single-phase compound for x = 1. Grain morphology has been studied by Scanning electron microscope (SEM: JOEL-IT300). By Impedance Analyzer (HIOKI-IM3536) dielectric properties such as dielectric constant and loss tangent have been measured in a wide temperature range (RT-500° C) and also with a wide range of frequency(1 kHz-1MHz). This dielectric result confirms the Ferroelectric nature of all the samples and with increasing content of BiFeO3, the dielectric constant decreases. [ABSTRACT FROM AUTHOR]

The solid solution of (Ba5TbTi3V7O30)x(BiFeO3)1-x has been synthesized by solid-state reaction technique with different x values. XRD (X-Ray Diffractogram) study confirms the formation of single-phase compound for x = 1. Grain morphology has been studied by Scanning electron microscope (SEM: JOEL-IT300). By Impedance Analyzer (HIOKI-IM3536) dielectric properties such as dielectric constant and loss tangent have been measured in a wide temperature range (RT-500° C) and also with a wide range of frequency(1 kHz-1MHz). This dielectric result confirms the Ferroelectric nature of all the samples and with increasing content of BiFeO3, the dielectric constant decreases. [ABSTRACT FROM AUTHOR]

The temperature dependences of the dielectric permittivity and dielectric loss tangent in the ferroelectric ceramic Ba0.8Sr0.2TiO3 have been studied at frequencies from 25 Hz to 120 Hz. It was found that the phase transition at the Curie point (ТС ≈ 338 K) is diffused in the temperature range of ∼ 30 K. The temperature dependence of the local order parameter plotted based on dielectric measurement data confirms the diffusion of the phase transition, which begins by the arising of local polar regions at Burns temperature. The revealed dependences of the dielectric loss maximum near the TC on the heating rate of the sample and frequency are well explained in the framework of the fluctuation model of low-frequency dielectric losses during a first-order phase transitions. [ABSTRACT FROM AUTHOR]

A new Aurivillius Bi5Ti3Fe0.5Ni0.5O15 compound was prepared using the conventional ceramic technology. The features of the temperature dependences of the dielectric constant ε′ and the dielectric loss tgδ were studied in the temperature range from 300 to 750 K. These dependences indicate a significant conductivity contribution to the ε′ and tgδ as well as the presence of a relaxation process. The ac conductivity was calculated, the hodograph of the impedance of the sample was plotted, and the activation energy of the dielectric relaxation process was estimated. A comparison of the activation energy of the total electrical conductivity and electrical conductivity in the grain bulk showed that the electrical conductivity of the studied compound is mainly due to the electrical conductivity of the grains boundaries. [ABSTRACT FROM AUTHOR]

The temperature dependences of the dielectric permittivity and dielectric loss tangent in the ferroelectric ceramic Ba0.8Sr0.2TiO3 have been studied at frequencies from 25 Hz to 120 Hz. It was found that the phase transition at the Curie point (ТС ≈ 338 K) is diffused in the temperature range of ∼ 30 K. The temperature dependence of the local order parameter plotted based on dielectric measurement data confirms the diffusion of the phase transition, which begins by the arising of local polar regions at Burns temperature. The revealed dependences of the dielectric loss maximum near the TC on the heating rate of the sample and frequency are well explained in the framework of the fluctuation model of low-frequency dielectric losses during a first-order phase transitions. [ABSTRACT FROM AUTHOR]

Polycrystalline ceramics, SrBi4Ti4O15 (SBT) and Sr0.2Na0.4Nd0.4Bi4Ti4O15 (SNBT), were synthesized by solid state sintering method using planetary ball mill. The stoichiometric powders were ground for 10 hours. Single phase formation was established from the XRD results. The highest peak (119) was seen at 30°. X-ray diffraction results indicated decreased cell volume and orthorhombic distortion with the substitution of Na+ and Nd3+ in place of Sr2+. The lattice parameters were measured using Unitcell software. Grain size as well as grains random orientation was observed from scanning electron microscope results. Dielectric properties were measured using Novo control dielectric analyzer, from room temperature to 1200 °C at frequencies 1 kHz, 10 kHz, 50 kHz, 100 kHz, 500 kHz, and 1 MHz. The dielectric constant and loss decreased whereas the Curie temperature increased when Na+ and Nd3+ were substituted to A- site in SBT. This ceramic has enhanced thermal stability thus making this ceramic appropriate for sensor applications at high temperatures. [ABSTRACT FROM AUTHOR]

Ferroelectric crystal TGS has different properties in ferro phase. Five phases appear distinct down the transition point till 30 °C. Crystals were grown at 52 °C by solvent evaporation in para phase, samples were polished and silver electrode were painted. Spectrometer Alpha-A Novocontrol was used for dielectric measurements (1-107 Hz), crossing Curie point from 65 °C to zero Celsius at a pace of 0.6 °C/minute. The decomposed curve ε"gives the dielectric losses and conduction losses. This component, at small frequency is huge and allow to estimate losses directly. The curve Ps2(T) shows 5 zone of temperature dependent intervals in ferro phase, from Tc to about 30 °C, where the transition is finished. The three type of relaxation: LOW, MIDDLE and HIGH, correspond to domains and to relaxation of several group in the structure. Crystal properties appear unstable on the temperature interval 46/47 °C ÷ Tc. All relaxation time behaves opposite with temperature on this interval, versus the data found upper 46/47 °C. The frequency coefficient N shows distinct ranges of linear temperature dependence on the interval 25-45 °C. On the zone 46 °C-Tc, coefficient shows a non-Arrhenius temperature dependence. [ABSTRACT FROM AUTHOR]

The La2/3Cu3Ti4O12 (LCTO) ceramic samples with a higher permittivity were prepared by the sol-gel technique. The study indicated that the effects of dc bias on grain boundaries electrical properties were very evident, but the grain electrical properties were independent of dc bias. The dielectric constant decreased whereas the dielectric loss increased with increasing of dc bias, and the resistances and the activation energies of grain boundaries decreased. According to the analysis of impedance and the I–V curve, there was a potential barrier existed at the grain boundaries of LCTO ceramic samples, which be considered as the Schottky potential barriers. [ABSTRACT FROM AUTHOR]

Nanotubes of nickel ferrite were prepared by citrate method and were used in nanocomposite synthesis via in situ polymerization technique. The structural and surface morphology characterization was carried out by FTIR, XRD, and SEM techniques. FTIR spectra show the characteristic peaks of benzenoid ring, quinoid ring, and nickel ferrite stretching of tetrahedral and octahedral sites. XRD pattern shows that NiFe2O4 nanotubes has a cubic spinal structure and remains undistorted even after dispersion in polyaniline matrix. The SEM image of 15% wt nanocomposite shows that the polyaniline coated nickel ferrite nanotubes form a length about 100 nm. Furthermore, the DC conductivity shows three steps conductivity feature and among all prepared nanocomposites, 15% wt one shows high conductivity of 1.89 S/cm. This is due to high absorption of activation energy 0.213 × 10−2 J/mol and elongation of nanocomposites chain length which is confirmed from the negative thermal coefficient graph. The VSM study shows the saturation magnetization decrease after formation of polyaniline nanocomposite. The dielectric properties were analyzed by impedance analyzer and it was found that 15% wt nanocomposite shows the lowest dielectric constant and dielectric loss as a result of high ac conductivity of about 1.32 S/cm which is due to sharp drop in bulk resistance and low relaxation time of 0.1375 µsec as evidenced from cole–cole plot. [ABSTRACT FROM AUTHOR]

The dense ceramics (Na0.47Bi0.47Ba0.06)0.97Sr0.03TiO3 were sintered in nitrogen atmosphere. The weight loss during sintering is 0.2%. The mean size of grains is about 1.5 μm. The dielectric permittivity and dielectric loss of the ceramics at room temperature and 1 kHz are 1836 and 0.05, respectively. The dielectric spectra of the unpoled and poled ceramics were measured. The diffuse dielectric behavior was studied via the Curie-Weiss law and modified Curie-Weiss law. The ceramics exhibit excellent ferroelectric properties. At room temperature, the d33 is as high as 157 pC/N. The ceramics exhibit excellent temperature stability of d33 between room temperature and 115 °C. [ABSTRACT FROM AUTHOR]

Ba0.985Bi0.01Mn0.067Ti0.933O3 (BBMT) ceramic samples were prepared using solid phase and precipitation methods. The influence of preparation method on phase composition, microstructure, and dielectric properties of BBMT ceramic samples was studied. Results show that grain size of ceramic sample prepared by solid-phase method (BBMT-1) was not uniform and was larger than 1 µm. The dielectric peak at the Curie temperature was sharp and the tangent loss was large (0.067). Fine-grained ceramics (BBMT-2) with uniform grain size (∼300 nm) were prepared by precipitation, and these ceramics exhibited broadened, flattened permittivity peaks. At room temperature, BBMT-2 ceramic samples have high dielectric constant of 1280 and low dielectric loss of 0.028, and samples exhibit good stability at temperatures ranging from −60 to 110 °C. These materials have potential applications in multilayer ceramic capacitors (MLCCs). [ABSTRACT FROM AUTHOR]