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Zinc substituted cobalt ferrite nanoparticles with elemental composition Co${}_{1-x}$Zn_xFe₂O₄ ($x=0.0$, 0.2, 0.4, 0.6) were prepared by the sol-gel auto-combustion technique using Co, Fe, Zn nitrate as a precursor where nitrates to citrate was 1:3. The as prepared powder of cobalt zinc ferrite was sintered at 900^∘C for 3h. Structural, morphological, dielectric and magnetic properties were studied by x-ray diffractometer (XRD), scanning electron microscope (SEM), high precision impedance analyzer and vibrating sample magnetometer (VSM), respectively. The peaks obtained from the XRD confirmed samples having crystallite ($\sim$32–36nm) single phase inverse spinel structure without any traceable impurity. Lattice parameters were calculated from XRD and it increases with Zn content. SEM revealed irregularly shaped grains ($\sim 0.5$–0.7$\mu$m) morphology with heterogeneous distribution. The dielectric constant (${\epsilon }^{\prime }$) and dielectric loss ($tan\delta$), have been measured as a function of frequency at room temperature. The dependence of ${\epsilon }^{\prime }$ and $tan\delta$ with frequency showed the normal dielectric behavior in accordance with the Maxwell-Wagner type of interfacial polarization and electron hopping change between Co${}^{2+}$ and Co${}^{3+}$ as well as between Fe${}^{2+}$ and Fe${}^{3+}$ ions at octahedral sites.

The temperature coefficient of permittivity ($\mathrm{\text{TC}}\epsilon$) of BaTiO₃–Bi(Me)O₃ solid solutions were investigated. It was determined that as the tolerance factor was decreased with the addition of Bi(Me)O₃, the $TC\epsilon$ shifted from large negative values to $\mathrm{\text{TC}}\epsilon$ values approaching zero. It is proposed that the different bonding nature of the dopant cation affects the magnitude and temperature stability of the permittivity. This study suggests that the relationship between tolerance factor and $\mathrm{\text{TC}}\epsilon$ can be used as a guide to design new dielectric compounds exhibiting temperature-stable high permittivity characteristics, which is similar to past research on perovskite and pyrochlore-based microwave dielectrics.

Lead-free sodium–potassium niobate-based piezoelectric materials are most intensively studied in order to replace the widely used Pb-based ones. In this work, the effects of modification of compositions by donor and acceptor dopants in the A- and B-sites of perovskite lattice on structure, dielectric, ferroelectric, and piezoelectric properties of ceramics from Morphotropic Phase Boundary in the ($1-x$)(K${}_{0.5}$Na${}_{0.5}$)NbO₃–$x$BaTiO₃ system and in compositions with $x=0.05$ and 0.06 additionally doped by Ni${}^{3+}$ cations have been studied.

The study aims to investigate the structural and dielectric properties of perovskite La${}_{1-x}$Sr_xFeO₃ ($x$ = 0.1, 0.2, 0.3, and 0.4) synthesized by sol–gel and sintering methods. X-ray diffraction (XRD), transmission electron microscopy (TEM), and LCR-Meter were used to identify the phase, crystallography parameters, morphology, particle size, and electrical behavior of the synthesized perovskite materials. The samples showed a single-phase orthorhombic crystal structure with Pbnm space group. Sr-substitution induced the volume unit cell and crystallite size to decrease. The synthesized nanoparticles were uniform and homogeneous with the particle size less than 200nm. Impedance spectroscopy (IS) was used to explain the electrical behavior as a function of frequency (100Hz to 1MHz) at various temperatures (300–373K). The presence of small polarons as charge carriers within the grain and grain boundary were elucidated from the electrical conductivity experiments. Sr-substitution caused the dielectric constant and electronic conductivity to increase with the highest values obtained from La${}_{1-x}$Sr_xFeO₃ ($x=0.4$).

SrTiO₃/ZnTiO₃ heterolayered thin films were fabricated by spin coating Sr–Ti and Zn–Ti sol–gel precursors on fused silica substrate. The SrTiO₃ and ZnTiO₃ were coated alternatively to form ABAB heterolayered thin films. The thickness of individual layers was tailored by controlling the coating layers. The structure characterization of the thin films showed independent structure of each layer while the microwave dielectric properties and optical band gaps can be tuned by changing the layer configuration. The effects of the layer configuration on the dielectric and optical properties were studied.

Dielectric-structure-based wakefield acceleration provides a viable approach to achieving the luminosity, efficiency, and cost requirements of a future linear collider as well as future x-ray light sources. This technology is capable of accelerating electrons and positrons at the substantially high gradients needed. Important progress in the development of dielectric wakefield accelerators has been made both experimentally and theoretically in the past few years. In this article we provide an overview of the basics of dielectric wakefield acceleration and major developments to date.

Ferroelectric materials are considered to be the most competitive energy storage materials for applications in pulsed power electronics due to excellent charge–discharge properties. However, the low energy storage density is the primary problem limiting their practical application. In this study, (1$-x$)Na${}_{0.5}$Bi${}_{0.5}$TiO₃–$x$Sr${}_{0.7}$La${}_{0.2}$TiO₃[(1$-x$)NBT–$x$SLT] ferroelectric ceramics are found to exhibit excellent energy storage performances through a synergistic strategy. As the SLT concentration increases, the relaxation characteristic increases significantly and the breakdown strength increases dramatically from 150 kV/cm to 220 kV/cm. The recoverable energy storage density of the 0.55NBT–0.45SLT ceramic is 2.86 J/cm³ with an energy storage efficiency of 88% under an electric field of 220 kV/cm. Furthermore, the ceramic with $x$ = 0.45 mol exhibited excellent energy storage stability in the ranges of 20–180${}^{\circ }$C (temperature) and 1–125 Hz (frequency). These excellent properties demonstrate the potential of (1$-x$)NBT–$x$SLT ceramics when used as dielectric capacitors in pulsed power systems.

Most particle accelerators today are expensive devices found only in the largest laboratories, industries, and hospitals. Using techniques developed nearly a century ago, the limiting performance of these accelerators is often traceable to material limitations, power source capabilities, and the cost tolerance of the application. Advanced accelerator concepts^a aim to increase the gradient of accelerators by orders of magnitude, using new power sources (e.g. lasers and relativistic beams) and new materials (e.g. dielectrics, metamaterials, and plasmas). Worldwide, research in this area has grown steadily in intensity since the 1980s, resulting in demonstrations of accelerating gradients that are orders of magnitude higher than for conventional techniques. While research is still in the early stages, these techniques have begun to demonstrate the potential to radically change accelerators, making them much more compact, and extending the reach of these tools of science into the angstrom and attosecond realms. Maturation of these techniques into robust, engineered devices will require sustained interdisciplinary, collaborative R&D and coherent use of test infrastructure worldwide. The outcome can potentially transform how accelerators are used.

Polycrystalline NiCuZn ferrite (Ni_xCu${}_{0.3}$Zn${}_{0.7-x}$Fe₂O₄; $x=0.2$, 0.3, 0.4 and 0.5) were prepared through sol–gel auto combustion method applying double sintering technique. Structural, morphological, elemental analyses (EDS), Fourier-transform infrared spectroscopy (FTIR), Direct Current (DC) electrical resistivity, dielectric, magnetic and optical properties of prepared samples were analyzed. XRD profiles reveal the formation of simple cubic spinel structure without any traceable impurity. The average crystallite size lies within the range of 22–29nm. Lattice parameter decreases with increasing Ni concentration. Room temperature DC resistivity was recorded from $6.39\times 10^5$ to $3.79\times 10^5$$\mathrm{\Omega }$cm. Both dielectric constant ($\dot{\epsilon }$) and loss factor (tan$\delta$) were decreased with increase of frequency while AC conductivity increases. FTIR absorption peak occurred at three different frequency ranges at 570–577cm${}^{-1}$, 1635–1662cm${}^{-1}$ and 3439–3448cm${}^{-1}$. Magnetic properties were investigated by using vibrating sample magnetometer (VSM). Decreasing trends were observed for saturation magnetization ($M_s$), magnetic coercivity ($H_c$) and remanant magnetization ($M_r$) with the increase of Ni content. Optical band gap ($\sim$2.70–2.79eV) were calculated from diffuse reflectance data by using Kubelka–Munk function.

The advancement of crystal growth and characterization methods allows us to investigate new substances with excellent nonlinear optical characteristics. To synthesize nonlinear optical material L-histidine hydrochloride hydrate (L-HHCLH), the gradual evaporation process was used. The produced samples were characterized by single-crystal X-ray crystallography, Fourier transform infrared (FTIR) and Raman spectroscopy, UV–visible (UV–Vis) spectroscopy, second harmonic generation (SHG) test, dielectric, and mechanical investigations. The L-HHCLH sample was crystallized in an orthorhombic structure with the P2₁2₁2₁ space group, as verified by the crystallographic data. FTIR and Raman spectroscopy were applied to examine the molecular vibrations and availability of the functional groups of the compound. The L-HHCLH is significantly transparent across the UV and visible ranges, as shown by the UV–Vis spectra measurements. The bandgap of L-HHCLH is 5.45 eV. The SHG test showed that the L-HHCLH crystals produced a significant amount of SHG output thrice that of the potassium dihydrogen phosphate (KDP) sample. The frequency dependences of the dielectric parameters were investigated in the dielectric tests. With increasing frequency, both the dielectric constant and loss dropped exponentially. The crystal hardness was determined using a microhardness test.

Flexible Nd-doped BaTiO₃@Al₂O₃/polyvinylidene fluoride (PVDF) composites have been successfully developed. With the reaction temperature of 70^∘C, Nd-doped BaTiO₃@Al₂O₃ particles display uniform core–shell structures and disperse well in the PVDF matrix. Due to the benign dielectric properties of Nd-doped BaTiO₃ and great suppression of the Al₂O₃ coating on the leakage current and dielectric loss, the Nd-doped BaTiO₃@Al₂O₃/PVDF composites with different Nd-doped BaTiO₃@Al₂O₃ filling ratios (0–4vol.%) exhibit relatively good dielectric and energy storage performance. Among them, the maximum discharged energy density of 8.6J/cm³ was achieved in the composite with 1vol.% Nd-doped BaTiO₃@Al₂O₃ loading.

Present study is carried out to understand the effect of conducting polymer, polypyrrole (PPy) on structural, morphological, thermal and dielectric properties of bio-compatible polymer blend film of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP). The growth of PPy in the matrix of PVA–PVP was analyzed using XRD, FT-IR and SEM studies. The shifting in positions and broadening of XRD diffraction peaks of PVA–PVP-PPy from that of PVA–PVP indicates the structural modification and reduction in the crystallinity of the PVA–PVP due to incorporation of PPy. The SEM studies suggest scattered growth of PPy in PVA–PVP matrix at lower concentration of pyrrole monomer. As the monomer concentration is increased, the uniform and interconnected growth of PPy was observed in SEM micrographs. The TGA thermograms show faster thermal degradation of PVA–PVP- PPy films at lower temperature as compared to PVA–PVP films. The blend films of PVA–PVP- PPy exhibited enhanced values of dielectric constant and ac conductivity as compared to the virgin blend film which are observed to increase with increasing concentration of PPy. The high dielectric constant with high ac conductivity exhibited by PVA–PVP-PPy film suggests its possible application as flexible dielectric material for the development of biosensors, energy storage devices in field of green organic electronics.

Developing environmental-friendly materials with high-density energy storage is of paramount importance to meet the burgeoning demands for energy storage. In this study, we harness the modulation of a multicomponent solid solution by introducing KNN as a third element into the BNT–BST system, thereby achieving a marked enhancement in both energy storage performance and the temperature stability of the dielectric constant. BNBST–4KNN stands out for its exceptional dielectric stability, with a dielectric constant variation rate within 10% across a broad temperature range of $40^{\circ }$C to $400^{\circ }$C, a feat attributed to the flattening and broadening of the $T_m$ peak. BNBT–2KNN exhibits superior energy storage capabilities, with an energy storage density of 1.324 J/cm³ and an energy storage efficiency of 72.3%, a result of the P–E loop becoming more slender. These advancements are pivotal for the sustainable progression of energy storage technologies.

Naturally, existing lignocelluloses fibers showed outstanding potential in paper industry and other conventional applications. On the other hand, lignocellulose fibers are suitable candidate for high-tech applications under the scope of abundance, flexibility, light-weight and environment friendliness. In this study, paper sheets were prepared from lignocelluloses fibers extracted from self-growing plant, typha angustifolia. Lignocelluloses paper sheets were characterized for scanning electron microscopy (SEM), universal testing machine (UTM) and vector network analyzer (VNA). Flexible paper sheets displayed a tensile strength of 9.1 MPa and further used as a substrate in patch antenna to observe dielectric characteristics. The patch antenna is designed at 5.1 GHz which showed return loss less than −10 dB and dielectric constant 3.71. The use of lignocelluloses paper sheet as a substrate in patch antenna will provide the opportunity of miniaturization of size and weight in comparison of a jean substrate based antenna.

In this paper, we study the preparation of titanate/polypyrrole core-shell rod-like composite particles. The mere titanate rod-like particles were prepared as core material and PPy was polymerized on their surface in different amounts. Rheological measurements showed that under an applied external electric field, shear stress of these materials significantly increased with amount of PPy in the shell layer. The yield stresses obtained from the Cho-Choi-Jhon model were correlated with dielectric properties of suspensions. Polarizability as a measure of particle polarization obtained from Havriliak–Negami model of dielectric spectra increases with the content of PPy in the samples. Furthermore, role of particle concentration and silicone oil viscosity was also investigated.

xPb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃(xPIN–yPMN–zPT) ternary ceramics with morphotropic phase boundary (MPB) composition were synthesized by columbite precursor method. xPIN–yPMN–zPT phase diagram was investigated by x-ray diffraction and dielectric measurements. According to the results of dielectric measurements, the Curie temperatures (T_c) and rhombohedral to tetragonal phase transition temperature (T_r−t) were found to be in the range of 173–212°C and 114–155°C, respectively, indicating that the T_r-t was increased with adding PIN component. In the MPB region, the highest T_r-t = 155°C was found in 0.32PIN–0.38PMN–0.30PT ceramic, that greatly expanded temperature usage range.

This work prepares (Ba${}_{0.5}$Sr${}_{0.5}$)TiO₃ (BST)-doped (Bi${}_{1∕2}$Na${}_{1∕2}$)TiO₃ (NBT) lead free ceramics through conventional solid reaction method and analyzes the doping effect of BST on phases, microstructure, dielectric and ferroelectric properties. The phase and structure of the NBT-BST ceramics were investigated through X-ray diffractometer (XRD) and Raman. The XRD results showed that BST has diffused into the NBT lattices to form a stable solid solution; while, Raman spectrum showed the bands at low frequency are different with that of pure NBT and divided into two ranges around 247cm${}^{-1}$ and 303cm${}^{-1}$. Relative dense and homogeneous ceramic microstructures could be achieved, with the observation of a slight decrease in average grain size with the increase of BST doping content. The dielectric and ferroelectric properties were also investigated. The dielectric constant increases gradually with increasing the temperature to $T_{\mathrm{\text{m}}}$, and then decrease. The temperature dependence property showed diffused phase transition near $T_{\mathrm{\text{m}}}$. The polarization-electric field ($P$-$E$) hysteresis loops of BST-doped NBT ceramics showed typical ferroelectric or relaxor nature. Both the $E_{\mathrm{\text{c}}}$ and $P_{\mathrm{\text{r}}}$ increased first, then decreased with respect to the increase of the BST content.

In this work, we report the dielectric properties of Single wall Carbon Nanotubes (SWCNTs)-based phantom that is mainly composed of gelatin and water. The fabricated gelatin-based phantom with desired dielectric properties was fabricated and doped with different concentrations of SWCNTs (e.g., 0%, 0.05%, 0.10%, 0.15%, 0.2%, 0.4% and 0.6%). The dielectric constants (real ${\epsilon }^{\prime }$ and imaginary ${\epsilon }^{\prime \prime })$ were measured at different positions for each sample as a function of frequency (0.5–20GHz) and concentrations of SWCNTs and their averages were found. The Cole–Cole plot (${\epsilon }^{\prime }$ versus ${\epsilon }^{\prime \prime })$ was obtained for each concentration of SWCNTs and was used to obtain the static dielectric constant ${\epsilon }_s$, the dielectric constant at the high limit of frequency ${\epsilon }_{\infty }$ and the average relaxation time $\tau$. The measurements showed that the fabricated samples are in good homogeneity and the SWCNTs are dispersed well in the samples as an acceptable standard deviation is achieved. The study showed a linear increase in the static dielectric constant ${\epsilon }_s$ and invariance of the average relaxation time $\tau$ and the value of ${\epsilon }_{\infty }$ at room temperature for the investigated concentrations of SWCNTs.

The modification of the structure lanthanum orthoferrites (LaFeO${}_3)$ to obtain ceramic materials with enhanced structural, optical, and electrical properties constitutes an active area of research. The preparation of La${}_{0.8}$Pb${}_{0.2}$(Fe, Ti)${}_{0.5}$O₃ (LPFTO) ceramic nanoparticles by following a cation substitution approach from LaFeO₃ using sol–gel and sintering methods is described. The electrical and dielectric properties of the obtained material are investigated. The contribution of grain and grain boundary in the conduction mechanism is demonstrated by complex impedance analysis. The LPFTO ceramic nanoparticles exhibit a giant dielectric constant of the order of 10⁸. The conductivity analysis suggests the occurrence of thermally activated semiconductor behavior. Moreover, the ferromagnetic–paramagnetic semiconductor transition temperature is observed at 385K. The ac conductivity behavior satisfies the nonoverlapping small-polaron tunneling (NSPT) model.

The perovskite (${\text{La}}_{0.7}$${\text{Ba}}_{0.3})$(${\text{Mn}}_{0.5}$${\text{Fe}}_{0.5}{){}_{1-}}_x$${\text{Zr}}_x$O₃, where $x$ = 0.1, 0.2 and 0.3, ceramics were synthesized by solid-state reaction method. The introductory structural studies were followed through by X-ray diffraction technique and the results have disclosed that all the samples were crystallized into an isolated phase. The Zr substitution in the resulting solid solutions increases the electrical conductivity and the maximum value of ac conductivity has been found to be $\sim$118.8 S ${}^{.}$ cm${}^{-1}$ for $x$ = 0.3 at 200${}^{\circ }$C (at 1 MHz). The frequency dependence of ac conductivity data follows Jonscher’s power law. The variation of the exponent $n$ versus temperature follows the nonoverlapping small polaron tunneling (NSPT) model. The dielectric relaxation has been observed to be of non-Debye nature for all measuring temperatures (50–200${}^{\circ }$C). The impedance spectroscopy reveals that all the samples exhibit negative temperature coefficient of resistance (NTCR) behavior. The prepared samples (for $x$ > 1) are supposed to be suitable for cathode materials in SOFCs.