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Bi(2/3)‐xSmxCu3Ti4O12 (BSCTO x = 0.05, 0.10, and 0.20) ceramics are synthesized using semi‐wet technique and an extensive investigation into their structural, morphological, and elemental properties, alongside dielectric and impedance behaviors, is meticulously carried out. X‐ray powder diffraction analysis unequivocally confirmed the formation of a monophasic BCTO cubic phase without any discernible secondary phases. and the crystallite size of the BSCTO ceramic, obtained by X‐ray diffraction using Debye Scherrer formula, range from 62 to 81 nm. Rietveld analysis reveals that ceramics have a body centered cubic structure with space group Im‐3. The Scanning electron microscope image displays the dense microstructure of the ceramics, while EDX analysis unveils the elemental composition of resulting products. Doping with Sm3+ induced a notable reduction in grain size, as observed through Scanning electron microscope and Atomic Force Microscope analyses, indicating Sm3+ hindered grain growth during sintering, potentially resulting in reduced dielectric constant (ε′). Dielectric constant and dielectric loss of the composition (x = 0.2) are found to be ≈$ \approx $152 and 0.04, respectively at room temperature (1 kHz). Impedance characteristics revealed a substantial increase in grain boundary resistance, leading to improved dielectric loss. The AC conductivity of BSCTO ceramics exhibited a frequency‐dependent increase satisfying to Johncher's power law. [ABSTRACT FROM AUTHOR]

The current study demonstrates the effect of Ni-substitution on the structural, dielectric and ferroelectric properties of Ba0.90Sr0.10Ti1-xNixO3 (where x = 0.000, 0.005, 0.015 and 0.025) ceramics, synthesized by solid-state reaction approach. A pure perovskite phase with tetragonal structure has been confirmed by X-ray diffraction (XRD) analysis. Scanning electron microscope (SEM) images revealed change in microstructure. The dielectric behavior of the prepared ceramics was investigated as a function of temperature (30–150°C) at different frequencies. The results indicate that there is an increase in dielectric constant (ϵRT) and low dielectric loss (tanδRT) were obtained at room temperature by substitution of Ni2+ ions in BST ceramics, offering a promising material for capacitor applications at room temperature. Room temperature P-E loops were recorded at different applied electric fields and typical hysteresis loops were obtained. Improvement in the values of Pr and Pmax was observed by substitution of Ni2+ ions. [ABSTRACT FROM AUTHOR]

In the present work, Ni0.6Cd0.4DyxFe2-xO4 (x = 0.0, 0.05, 0.10, 0.15, 0.20) nanoparticles (NPs) were synthesized by using sol–gel method. X-ray diffraction (XRD) patterns confirmed that the pure and dysprosium substituted Ni–Cd ferrites are in single-phase spinel structures, while a trace of DyFeO3 appears as a minor phase for higher concentrations (x = 0.10, 0.15 and 0.20). The Debye–Scherrer's method and Williamson–Hall (W-H) method were used to evaluate the crystallite sizes and lattice strain. Scanning electron microscope (SEM) images show that reduction of grain size with Dy3+ content. Elemental composition features of samples were examined by Energy-dispersive X-ray spectroscopy (EDS). The average particles size estimated from transmission electron microscopy (TEM) analysis is in good agreement with results obtained from XRD. The results showed that saturation magnetization (Ms) decreases and coercivity (Hc) increases with an increase in Dy3+ concentrations. The dielectric constant was found to decrease with increasing Dy content in Ni–Cd ferrites. [ABSTRACT FROM AUTHOR]

In the present work, CaCu3Ti4O12 (CCTO) nanoceramics with different grain sizes were prepared by spark plasma sintering (SPS) at different temperatures (SPS-800, SPS-900, SPS-975, and SPS-1050) of the mechanosynthesized nano-powder. Structural and microstructural properties were studied by XRD and field-emission scanning electron microscope measurements. The grain size of CCTO nanoceramics increases from 80 nm to ∼200 nm for the ceramics sintered at 800 °C and 975 °C, respectively. Further increase of SPS temperature to 1050 °C leads to micro-sized ceramics of 2-3 lm. The electrical and dielectric properties of the investigated ceramics were studied by impedance spectroscopy. Giant dielectric constant was observed in CCTO nanoceramics. The dielectric constant increases with increasing the grain size of the nanoceramics with values of 8.3×103, 2.4×104, and 3.2×104 for SPS-800, SPS-900, and SPS-975, respectively. For the micro-sized SPS-1050 ceramics, the dielectric constant dropped to 2.14×104. The dielectric behavior is interpreted within the internal barrier layer capacitance picture due to the electrical inhomogeneity of the ceramics. Besides the resistive grain boundaries that are usually observed in CCTO ceramics, domain boundaries appear as a second source of internal layers in the current nanoceramics. [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]

Abstract 20MO.55Bi 2 O 3.25B 2 O 3 (M = Sr, Ba) glasses have been prepared by conventional melt quenching method and t he Bi 24 B 2 O 39 (boron sillenite) crystalline phase by solid state reaction technique. The effect of variation in wt% of Bi 24 B 2 O 39 crystalline phase on 20SrO.55Bi 2 O 3.25B 2 O 3 (SBB) and 20BaO.55Bi 2 O 3.25B 2 O 3 (BBB) glasses has been investigated. The sintered density of the glass samples were characterized by Archimedes' method. The X-ray Diffraction method, Fourier Transform-Infrared (FT-IR) spectra and FT- Raman spectra are used for structural investigations, whereas Scanning Electron Microscope (SEM) analysis is used for the microstructural study. The effect of the Bi 24 B 2 O 39 crystalline phase as filler in the glass network is confirmed from the FT-IR and FT-Raman spectra. The dielectric properties of the selected samples, analyzed using an Impedance analyzer, show that the dielectric constant slightly increases with increase in the wt% of Bi24B2O39 crystalline phase on glasses and the BBB glasses show higher dielectric values than the SBB glasses. The glass ceramic composites show low sintering temperature (<650 °C), dielectric constant in the range 10–16 and dielectric loss of ~0.0069, suggesting that they can be used as promising candidates for Ultra Low Temperature Cofired Ceramic Applications(ULTCC). Highlights • Effect of Bi 24 B 2 O 39 crystalline phase on 20MO.55Bi2O3.25B2O3 (M=Sr,Ba) glasses were investigated for the first time. • The sintering temperature of glass ceramic composites is <650 °C. • The dielectric constant of glass ceramic composites is in the range 10–16 and dielectric loss is ~0.0069. • These glass ceramic composites are promising candidates for ULTCC Applications. [ABSTRACT FROM AUTHOR]

Highlights • A nondestructive method is developed for hydration monitoring of young concrete. • The dielectric properties are ideal indicators of the hydration process. • Additional details on hydration are obtained by using dielectric properties method. • Chemical admixtures is used to verify the application of this method. Abstract A nondestructive device is designed and employed to monitor the hydration of young concrete. The relative dielectric constant and amplitude can be measured by calculating the propagation time and intensity of electromagnetic impulses in young concrete, and the XRD and SEM are applied to investigate the mechanism of correlation between dielectric property and hydration process. Chemical admixtures (citric acid and triethanolamine) are used to verify the application of this method. The test results show that both the amplitude and relative dielectric constant (RDC) are ideal indicators of the hydration process. Microstructure observations demonstrate that the dielectric properties are strongly related to the formation of hydration products and changes of microstructure. The final setting time can also be achieved based on the amplitude measurement. This research provides theoretical and technical foundations for investigating the hydration of concrete, which enables us to have a better understanding of the hydration process. [ABSTRACT FROM AUTHOR]

In the present study, the lanthanumsubstituted strontium ferrite particles with general formula, SrLaFeO ( x = 0, 0.10, 0.15, 0.20, and 0.25) were prepared using citrate auto-combustion method. These ferrites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM), and vector network analyzer (VNA). X-ray diffraction patterns show the formation of M-type hexaferrite phase without any secondary phases for all the synthesized samples. The complex permittivity ( ε - j ε ) and complex permeability ( μ - j μ ) were measured using VNA in X-band (8.2-12.4 GHz) and Ku-band (12.4-18 GHz) frequency range at room temperature. More than 90 % absorption was obtained in the Ku band for all the La substituted strontium ferrites. The composition x = 0.15 exhibits a minimum reflection loss of −20.66 dB at 16.5 GHz and an absorption bandwidth of 2.1 GHz (15.63 to 17.64 GHz) with an absorber layer thickness of 1.6 mm. These materials can be used as cost-effective and thinlayer microwave absorbers in higherfrequency range. [ABSTRACT FROM AUTHOR]

The controlled synthesis of TiO/SiO/CdS-nanocomposites fabrication by hydrothermal assisted route has been successfully performed. Without any doubt this novel strategy is one of the central issues in current Nanotechnology and Materials Science. Those hybrid nanocomposites were characterized by spectroscopes and electron microscopic in several investigations, e.g. X-ray diffraction (XRD), Raman spectroscopy, UV-visible spectroscopy, Scanning electron microscope (SEM) and dielectric dispersion. The average grain size was found to be 28 nm by using X-ray diffraction analysis and nanocomposites were confirmed by the Scanning Electron Microscopy (SEM). The well crystalline distinguishable peak shifts of individual composite materials (e.g. Anatase titanium, SiO, CdS) were carried out by the Raman spectrum. Indeed, optical properties were obtained by UV-visible absorption spectrum and the calculated optical band gap of the nanocomposite was found to be 3.31 eV. Moreover, typical investigations of dielectric behavior, e.g. dielectric constant, dielectric loss, and AC conductivity properties were also carried out at different frequencies and ambient conditions of temperatures. A successful attempt revealed through this performance puts the hybrid nanostructure at the top level in the state of the art in application oriented research in high crystalline composite materials. [ABSTRACT FROM AUTHOR]

The effect of CrO on the microstructure and dielectric properties of SnO varistors doped with NbO and CoO was investigated. The density of ceramic samples was calculated and found increases from 6.6819 to 6.8704 g cm. It is observed in this figure that, independent of the CrO concentration, no other crystalline phase besides SnO is observed indicating that the system is single phase within the detection precision of the X-ray diffraction. The average crystallite size of the prepared samples using was estimated Scherrer's equation. A scanning electron microscope (SEM) was utilized in order to study the effect of variation of CrO content and its impact on the microstructure and electric properties. The obtained results show that, as CrO concentration increases the dielectric permittivity increases and ac resistivity decreases and then increases and takes it maximum resistivity at 0.5 mol%. The compositional dependence of the dielectric permittivity and ac resistivity has been explained in the light of the SEM micrographs. The obtained results show also that the sample of 0.5 mol% of CrO has highest resistivity and consequently low dielectric loss. So, it can be used in some technological applications such as transformer and inductor cores. [ABSTRACT FROM AUTHOR]

Synthesis of three different ratios of Al CoZnO powders were prepared using sol gel route. Structural and electronic properties of the synthesized material were investigated using X-ray diffraction and scanning electron microscope, vibrating sample magnetometer (VSM), ultraviolet (UV) spectroscopy and dielectric studies. Characterization results reveal that the particle size is of the range 4.84 nm to the maximum size of 19.86 nm with a morphological structures representing rounded and honeycomb shapes at different doping ratios. VSM results of the prepared samples reveal the ferromagnetic nature with the hysteresis curve representation. The optical band gap has been calculated as 3.1-3.8 nm from the UV spectroscopy results. Conductivity of the samples was calculated from dielectric constant and conductivity increases with increasing doping ratios. [ABSTRACT FROM AUTHOR]

In the present study, pure and Ni-doped ZnO/rGO nanocomposites (NCs) are reported using the cost-effective wet chemical route to explore their dielectric characteristics. The structural examinations using X-ray diffraction (XRD) exposed the hexagonal wurtzite structure in both pure and Ni doped ZnO samples. The presence of an additional secondary phase accredited to NiO was also observed in Ni doped sample. The microstructural investigations using scanning electron microscope (SEM) revealed that Ni addition in ZnO modified particle size, shape, and distribution. Using tunneling electron microscope (TEM), it demonstrated that nanoparticles are well distributed in rGO sheets. The dielectric constant and dielectric loss of NCs increased with rGO addition at low frequency region. The relatively higher observed value of the dielectric constant while lower loss is explained on the basis of oxygen vacancies generated. The ac conductivity of NCs increased gradually with frequency due to the tunneling and hopping mechanisms. These results demonstrated that the higher carrier generations at the interface between rGO and ZnO grains are due to the increased mobility of charge carriers. Thus, the synergetic effect among them has the potential for use in advanced microelectronic devices, for instance, a gate material in transistors, capacitance-based energy storage devices etc. • Using chemical method, Ni-doped ZnO/rGO NCs with stable hexagonal wurtiz crystal structure of ZnO were synthesized. • Particles with semicircular-shaped particles were found well distributed in the graphene sheet. • Temperature and frequency dependent response of dielectric constant, loss and conductivity behaviour were enlightened. • Finer grain size together with defect induced space charge polarization contributes to improved dielectric behaviour. [ABSTRACT FROM AUTHOR]

Using high energy ball milling technique the nanocrystalline PbNdTiO (where x = 0.01), abbreviated as PNT, ceramics with tetragonal shape has been synthesized and analyzed through X-ray diffraction and scanning electron microscope analysis. The frequency dependent ac conductivity and dielectric constant measurements of the PNT ceramics sintered at 800, 900, 1000 and 1100 °C has been performed in the 100-525 °C temperature range and the density of states at the Fermi level evaluated. The minimum hopping length and dielectric constants in PNT has been explained successfully using the correlated barrier hopping model. With first order correction to energy the quantum theory of ferroelectric has been applied to explain the dielectric behavior in the paraelectric phase. The explanation for density of states at morphotropic phase boundary and the conduction mechanism of charge transport were found to be in good agreement with the experimental observations. [ABSTRACT FROM AUTHOR]

Highlights: [•] A polyvinyl alcohol film doped with C-ZnO nanoparticles was prepared by solution casting technique. [•] Dielectric constant, dielectric loss, and electrical conductivity gradually decrease with filler concentration. [•] XRD scans demonstrated the semi crystalline nature of the composites. [•] SEM images reveal the uniform distribution of nanoparticles within the polymer matrix. [ABSTRACT FROM AUTHOR]

Lead-free PTCR ceramics based on BiO and YO doped BaCaTiO were fabricated by the conventional mixed oxide method, while BiO and YO were doped directly or after pre-calcining, in the molar ratio of BiO:YO = 1:1. There were two synthesizing route, i.e. the materials were pre-calcined at 900 °C to obtain BiYO firstly and then doped into the basic materials, and the materials were directly doped into the starting materials, both of which could obtain samples with different electrical properties and PTCR behavior. The samples were characterized by using X-ray diffraction, scanning electron microscope, dielectric constant-temperature and resistivity-temperature measurement instrument. It was revealed that the perovskite lattice, the microstructure and the PTCR behavior of BaCaTiO varied with different doping contents and methods. A further research was conducted so as to study the electrical properties of ceramics by impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Strontium niobate SrNb2O6 has been synthesized by columbite solid-state reaction method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and temperature as well as frequency dependence of dielectric and impedance study. XRD analysis indicates single phase formation of the compound with ∼180nm crystallite size. Study of SEM micrographs pointed out that prepared material has good sinterability and enough density with homogeneous grain distribution. It was found that the magnitude of relative dielectric constant (ɛ r) was relatively high with low dielectric loss compared with reported columbite compounds. Impedance spectroscopy was used to characterize the electrical behavior of the compound. AC impedance spectrum results indicate that the relaxation mechanism of the material is temperature dependent and has bulk and grain boundary contribution in different temperature ranges. [Copyright &y& Elsevier]

Abstract: Various high and low permittivity dielectric material systems were studied frequently. However, middle permittivity dielectric ceramics with ɛ r values ranging from 40 to 80 were seldom reported. For adapting to the development of microwave communication technology, a new Y2O3–TiO2 system ceramic was investigated in this paper. The effects of different k values on the properties of Y2O3–kTiO2 (k =1, 1.5, 2, 2.5) microwave dielectric ceramics were studied by impedance analyzer, network analyzer, X-ray diffraction apparatus (XRD) and scanning electron microscope (SEM). It is shown that the major crystal phases of the samples are pyrochlore except when k value is 1. The ceramic with a optimal composition (Y2O3:TiO2) sintered at 1460°C exhibits the best dielectric properties: ɛ r ≈54, tan δ ≈9.0×10−4 (1MHz); ɛ r ≈54, Q·f =6565.8GHz (4.65GHz), τ f =−31ppm/°C. [Copyright &y& Elsevier]

Abstract: The SiC(B) solid solution powders were synthesized via combustion reaction of Si/C system in Ar atmosphere, using boron powder as the dopant and polytetrafluoroethylene as the chemical activator, which were investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM) and Raman spectra. Results show that the prepared powders are C-enriched SiC with C antisites and sp2 carbon defects in which the sp2 carbon is transformed to the sp3 carbon due to boron doping. The electric permittivities of the prepared powders were determined in the frequency range of 8.2–12.4GHz. The dielectric real part ɛ′ and dielectric loss tan δ of undoped powder have maximum values (ɛ′=5.5–5.3, tan δ =0.23–0.20), and decrease with increasing boron content. The mechanism of dielectric loss by doping has been discussed. [Copyright &y& Elsevier]

• The prepared Sn 4 Sb 6 S 13 (TAS) thin film on PAA at different deposition temperatures results an evolution in the crystal sizes and shapes at the surface. • XRD and Raman patterns presented an increase in the peak intensity and a change in the peaks position toward higher energy indicating the crystalline quality enhancement. • The average R% spectra decreased significantly from 71.6% for the PAA layer to 59.9%, indicating the large absorbance of the deposited compound on PAA substrates. • The average reflectivity of TAS/PAA multilayered structure increases significantly from 59.9%–61.4% by increasing substrate temperature from 30 to 140 °C, owing to an improvement in the film crystallization. • The refractive index (n), extinction coefficient (k), the real and imaginary dielectric constants, as well as the thickness of TAS/PAA multilayers were estimated from the ellipsometric measurements. In this study, the Sn 4 Sb 6 S 13 (TAS) nanocrystals were grown on the porous anodic alumina (PAA) templates through the vacuum thermal evaporation process at different deposition temperatures. The influence of deposition temperature on the microstructural and optical properties of TAS/PAA was investigated systematically. As the substrate temperature is increased, crystallite size increases while the strain and the dislocation density decrease. An improvement of the crystallinity is deduced from Raman spectra and X-Ray diffraction (XRD) patterns. The homogeneous distribution of TAS nanocrystals on PAA substrates was observed from surface morphology by using atomic force microscopy (AFM) and scanning electron microscope (SEM). The average reflectance of TAS/PAA films decreased significantly from 77 % to 60 % in the visible and near-infrared spectral regions, indicating the large absorbance of the deposited thin film. The optical parameters and thickness of TAS/PAA layers were estimated on the basis of spectroscopic ellipsometry measurements. [ABSTRACT FROM AUTHOR]