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A series of Sr4.5Ca0.5MTi3Nb7O30 [M = La0.5Nd0.5 (LN), La1/3Nd1/3Sm1/3 (LNS) and La0.25Nd0.25Sm0.25Eu0.25 (LNSE)] ceramics with different A-site configuration entropy were prepared, and the effects of the A-site configuration entropy on the dielectric and ferroelectric properties were investigated. Due to the combined effect of high entropy and solid solution, the best dielectric performance was achieved in the LNS composition, where the dielectric constant remained around 650 in the temperature range of 269–515 K with a change rate of less than 15%. Under the DC high voltage field up to 67 kV/cm, each component's polarization characteristics and dielectric constants obtained good electric field stability and temperature stability under a high electric field. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations at constant temperature and pressure were carried out to investigate the structural, dynamical, and dielectric properties of succinonitrile in its plastic and liquid phases at several thermodynamic states. A six-site united atom model was employed with a force field incorporating an intramolecular torsional term that accurately describes gauche and trans conformers. Analysis of the radial distribution function showed that succinonitrile adopts a body-centered cubic arrangement below its melting point, transitioning to a less ordered state in the liquid phase. In addition, examination of alignments between methylene bonds and the diagonals of the simulating cubic box revealed pronounced directional preferences in the plastic phase. The study of conformational states suggested that succinonitrile molecules predominantly adopt gauche conformations, which exhibit longer lifetimes than trans conformers. Spectral density analysis highlighted distinct peaks for different molecular sites, revealing significant differences between gauche and trans conformers. The correlation functions of bending and torsional angles, as well as vectors joining different atoms, illustrated a sensitivity to internal motions, which were notably faster for trans conformers. Differences in decay rates between trans and gauche conformers underscored the influence of gauche–trans transitions. The static dielectric constant, which has been derived from the total dipole moment, was primarily influenced by the contribution of the gauche conformers. In addition, the distance-dependent Kirkwood factor was computed, revealing antiparallel alignment at short distances. Finally, the dielectric relaxation time and the static dielectric constant values were compared with experimental data. [ABSTRACT FROM AUTHOR]

We critically examine a broad class of explicitly polarizable soft solvent models aimed at applications in dissipative particle dynamics. We obtain the dielectric permittivity using the fluctuating box dipole method in linear response theory and verify the models in relation to several test cases, including demonstrating ion desorption from an oil–water interface due to image charge effects. We additionally compute the Kirkwood factor and find that it uniformly lies in the range g K ≃ 0.7 –0.8, indicating that dipole–dipole correlations are not negligible in these models. This is supported by the measurements of dipole–dipole correlation functions. As a consequence, Onsager theory over-predicts the dielectric permittivity by 20%–30%. The mean square molecular dipole moment can be accurately estimated with a first-order Wertheim perturbation theory. [ABSTRACT FROM AUTHOR]

To maximize the piezoelectric performance of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystals, a pulse poling (PP) method is proposed in this study. This study investigates the effects of pulse poling on the piezoelectric and dielectric properties of these PMN–PT single crystals and explores the polarization rotation mechanisms. Our findings indicate a significant improvement in the piezoelectric properties postpulse poling. The optimal PP conditions are identified as 30 pulse numbers at a pulsed electric field of 5 kV/cm. The dielectric constant ɛT33/ɛ0 and piezoelectric coefficient d33 of PMN–0.28PT post PP are 7000–7700 and 2200–2530 pC/N, respectively, representing increases of 49% and 66% compared with those of postdirect current poling (DCP). Additionally, the domain structures of the PMN–0.28PT single crystals after various DCP and PP treatments are examined and compared using piezoelectric force microscopy. The enhanced piezoelectric properties are attributed to the finer domain structures, as well as increased domain wall density achieved through PP. This research introduces a novel domain engineering approach to improve the electromechanical properties of relaxor ferroelectric single crystals. [ABSTRACT FROM AUTHOR]

Perovskite structures have attracted extensive attention in microelectromechanical systems and nanoelectromechanical systems devices due to the high piezoelectric response and the low dielectric constant. The piezoelectric and dielectric properties of the tetragonal BiFeO3/BaTiO3 superlattices grown along the c-axis direction are investigated using density functional theory (DFT) and density functional perturbation theory. The calculated results demonstrate that the (BiFeO3)n/(BaTiO3)n (n = 1–5) superlattices exhibit a profoundly increased piezoelectric response compared to their bulk structures. The (BiFeO3)2/(BaTiO3)2 possesses the highest piezoelectric d33 of 697 pC/N among known lead-free perovskite systems. Furthermore, the (BiFeO3)2/(BaTiO3)2 superlattice possesses a low dielectric ɛ33, and its d33 at 2% tensile strain is 16 times larger than that of an unstrained equilibrium structure. This demonstrates that biaxial tensile strain significantly enhances the piezoelectric response. Combining the special quasirandom structure method with DFT, the structures of a 0.5BiFeO3–0.5BaTiO3 solid solution are predicted, and its calculated d33 is 58 pC/N, which is much smaller than that of a (BiFeO3)2/(BaTiO3)2 superlattice. The results suggest that the (BiFeO3)2/(BaTiO3)2 superlattice might be a potential candidate for nonvolatile random access memory, transducers and actuators, and nanoscale electronic devices. [ABSTRACT FROM AUTHOR]

The mechanical and dielectric properties of transformer insulating paper are key factors that require close attention to ensure optimal operation. In this study, a novel approach of enhancing properties by nanocellulose modification was proposed. To investigate the effect of doping, insulating paper with different doping mass fractions of cellulose nanocrystals (CNCs) was prepared, and multiple properties of the sample were characterized. By applying a doping concentration gradient, the non-monotonic trend in performance with doping levels was revealed, and the impact of doping concentration on the data variability was investigated. The effects of CNC doping on the surface pore size of the samples were analyzed by SEM (scanning electron microscopy) and a mercury intrusion method, and the regularity of CNC dispersion uniformity with doping concentration was investigated. The Brunauer, Emmett, and Teller model was employed to fit the water vapor adsorption isotherm data, providing an analysis of the impact of doping on hydrogen bond connections and the moisture adsorption properties. Tensile strength and Young's modulus were measured and analyzed using the Page model and the Halpin–Kardos model. The tensile strength of the 6 wt. % CNC-modified paper was increased by 6.91%. 10 wt. % CNC-modified paper had a Young's modulus increase of 11.98%. 3 wt. % CNC-modified paper has a 28.53% increase in the AC breakdown field strength and an 8.72% increase in the DC breakdown field strength. The influence of CNC on the dielectric properties of the insulating paper was discussed using the Havriliak–Negami (H–N) model. The results indicate that the introduction of CNC can effectively enhance the comprehensive performance of oil-immersed insulating paper. [ABSTRACT FROM AUTHOR]

Gratings are widely used for coupling into and out of evanescent and propagating electromagnetic modes, which are otherwise not accessible due to their large in-plane wave vector. A precise description of the optical response requires the knowledge of the grating geometry. Here, we present an investigation of the optical properties of dielectric gratings of sub-micron periodicity fabricated on a multilayer structure, which supports Bloch surface waves, by means of spectroscopic ellipsometry. Taking into account non-idealities, such as the finite spectral bandwidth, in the modeling process is shown to be a necessity for an accurate description of the observed spectra. The grating geometry determined from the analysis of ellipsometry data agrees very well with atomic force microscopy scans. Thus, our ellipsometric model is corroborated. [ABSTRACT FROM AUTHOR]

Ultrathin (1–4 nm) films of wide-bandgap semiconductors are important to many applications in microelectronics, and the film properties can be sensitively affected by defects especially at the substrate/film interface. Motivated by this, an in vacuo atomic layer deposition (ALD) was developed for the synthesis of ultrathin films of Ga2O3/Al2O3 atomic layer stacks (ALSs) on Al electrodes. It is found that the Ga2O3/Al2O3 ALS can form an interface with the Al electrode with negligible interfacial defects under the optimal ALD condition whether the starting atomic layer is Ga2O3 or Al2O3. Such an interface is the key to achieving an optimal and tunable electronic structure and dielectric properties in Ga2O3/Al2O3 ALS ultrathin films. In situ scanning tunneling spectroscopy confirms that the electronic structure of Ga2O3/Al2O3 ALS can have tunable bandgaps (Eg) between ∼2.0 eV for 100% Ga2O3 and ∼3.4 eV for 100% Al2O3. With variable ratios of Ga:Al, the measured Eg exhibits significant non-linearity, agreeing with the density functional theory simulation, and tunable carrier concentration. Furthermore, the dielectric constant ε of ultrathin Ga2O3/Al2O3 ALS capacitors is tunable through the variation in the ratio of the constituent Ga2O3 and Al2O3 atomic layer numbers from 9.83 for 100% Ga2O3 to 8.28 for 100% Al2O3. The high ɛ leads to excellent effective oxide thickness ∼1.7–2.1 nm for the ultrathin Ga2O3/Al2O3 ALS, which is comparable to that of high-K dielectric materials. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (h-BN) has excellent thermal conductivity and dielectric properties, which shows great potential for low-dimensional devices. However, mechanical properties of h-BN have not been comprehensively investigated through experiments. In this work, we conduct in situ direct tensile tests on freestanding single-crystal few-layer h-BN nanosheets with various layer numbers from 3 to 8, with an elaborate sample transfer and characterization protocol. Young's modulus of 573.8 ± 101.4 GPa and a tensile fracture strain up to 3.2% are revealed, which are comparable to its monolayer counterpart. Moreover, we find a tough-to-brittle transition in few-layer h-BN with the increase in layer number, which is attributed the interplay between the van der Waals interaction and in-plane covalent bonding. These findings could open up new possibilities in mechanical research of van der Waals materials and provide guidance for the design of h-BN-based devices and composites. [ABSTRACT FROM AUTHOR]

The effects of the solution's dielectric properties on the conformation and dynamics of star-shaped polyelectrolytes in shear flow are investigated using a hybrid simulation method coupling multi-particle collision dynamics and molecular dynamics. The simulation results showed that by modulating the dielectric properties of the solution, star-shaped polyelectrolytes showed a three-step dynamic behavior transition from tumbling to tank-treading to tumbling dynamics under shear flow. The analysis indicated that this distinct transition in dynamics could be attributed to the uneven distribution of counterions induced by shear on the chain, resulting in a change in the polyelectrolyte conformation and degree of segmental alignment in arms. These findings contribute to a comprehensive understanding of the non-equilibrium dynamics of star-shaped polyelectrolytes in shear flow and offer a viable approach for controlling the dynamic behavior of star-shaped polyelectrolytes by adjusting the dielectric properties of the solution. [ABSTRACT FROM AUTHOR]

Dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) is a widely used small-molecular p-type organic semiconductor. Despite the broad availability of high-performance DNTT transistors, there is a lack of investigation into other devices based on this semiconductor. In this study, rectifying diodes with DNTT as a single transport medium are fabricated and characterized. Realizing unipolar current rectification from asymmetric metal contacts, a number of physical and electrical properties of DNTT are made accessible. Current–voltage measurement, broad-band impedance spectroscopy, drift-diffusion simulation, and equivalent-circuit modeling are combined to quantify important parameters such as dielectric constant, trap energy, and lifetime. These results provide a practical reference for the design and optimization of diverse electronic devices incorporating DNTT. [ABSTRACT FROM AUTHOR]

(Bi0.5Na0.5)1−xBaxTiO3 lead-free ferroelectric ceramics were synthesized via the conventional solid-state reaction method. Structural and dielectric properties were investigated as a function of the doping concentration, considering x = 0, 2, 5, 8, 10, 12, 16, and 18 at. % Ba. The structural analyses were carried out from the x-ray diffraction technique, including the Rietveld refinement method, and Raman spectroscopy. Results confirmed the formation of the perovskite structure, revealing different crystalline symmetries, depending on the Ba2+ concentration: the single rhombohedral ferroelectric phase (R3c) for x = 0 and 2 at. %; coexistence of both rhombohedral ferroelectric (R3c) and tetragonal antiferroelectric (P4bm) phases for x = 5 at. % Ba; the single tetragonal antiferroelectric phase (P4bm) for x = 8 at. % Ba; coexistence of two tetragonal phases (antiferroelectric P4bm and ferroelectric P4mm) for x = 10 at. % Ba; and the single tetragonal ferroelectric phase (P4mm) for x = 12, 16, and 18 at. % Ba. The characteristics of the phases' transition, investigated from dielectric analysis, revealed the presence of two dielectric anomalies, which indeed have been associated to different phases' transitions, one of them showing relaxor-like characteristics. The obtained results offer new insights for a better understanding on the features of the phase diagram for the studied ceramic system, according to the different observed crystalline symmetries (ferroelectric and antiferroelectric) in a very wide doping concentration. In the light of the obtained results, a new phase diagram has been proposed considering a wider compositional range than those reported in the literature. [ABSTRACT FROM AUTHOR]

As investigations in the biomedical applications of plasma advance, a demand for describing safe and efficacious delivery of plasma is emerging. It is quite clear that not all plasmas are "equal" for all applications. This Perspective discusses limitations of the existing parameters used to define plasma in context of the need for the "right plasma" at the "right dose" for each "disease system." The validity of results extrapolated from in vitro studies to preclinical and clinical applications is discussed. We make a case for studying the whole system as a single unit, in situ. Furthermore, we argue that while plasma-generated chemical species are the proposed key effectors in biological systems, the contribution of physical effectors (electric fields, surface charging, dielectric properties of target, changes in gap electric fields, etc.) must not be ignored. [ABSTRACT FROM AUTHOR]

In this paper, the high-quality factor mullite microwave dielectric ceramic is employed to introduce in dielectric resonator antenna (DRA). The microwave dielectric properties of ɛr ∼ 5.8, Q × f ∼ 31 240 at 9.66 GHz, and loss tangent tanδ = 1/Q ∼ 2.7 × 10−4 can be obtained by the solid-state reaction method in mullite microwave dielectric ceramic sintered at 1700 °C. On this basis, the resonant modes of the proposed broadband high-gain rectangular DRA are analyzed by using a dielectric waveguide theoretical model and the antenna performance is evaluated by a commercial CST Microwave Studio 2021® software. It has been found that the proposed rectangular DRA can provide a broad bandwidth of 35.9%, a maximum gain of 10 dBi at 3.61 GHz, and a radiation efficiency of 90% in the range of 3.13–4.42 GHz. For demonstration, adequate consistency between the simulation results and the measurement results was achieved. The proposed DRA has great application potential and value in 5G communication scenarios requiring wideband and high-gain antenna. [ABSTRACT FROM AUTHOR]

Thermally stimulated discharge (TSD) technique is a traditional method in dielectric research, especially for electrets. However, in conventional open-circuit and short-circuit TSD techniques, it is difficult to distinguish the surface charge and body charge of dielectric materials. In particular with the test of polymer electrets, the deformation of the polymer film may take place during the measurement process, which will affect the accuracy of the experiment results. In this paper, a glass-assisting TSD (GA-TSD) technique is proposed to solve the above problems. The feasibility of the experimental technique is verified with the GA-TSD spectra of fluorinated ethylene-propylene copolymer electret films. In addition, their theory analysis is also accomplished. The influences of glass thickness, glass dielectric property, and metallizing on the glass on GA-TSD spectra are investigated. The results prove that the GA-TSD spectra can clearly distinguish the difference between surface charge and body charge according to the current direction. The quartz glass with the lowest dielectric constant is best suitable for the GA-TSD technique. The influence of the glass thickness and metallizing on the glass on GA-TSD spectra is little. [ABSTRACT FROM AUTHOR]

Ultrawide bandgap ZnGa2O4 (ZGO) thin films were grown on sapphire (0001) substrates at various growth temperatures with a perspective to investigate the electrical and optical characteristics required for high-power electronic applications. Due to the variation in the vapor pressure of Zn and Ga, severe loss of Zn was observed during pulsed laser deposition, which was solved by using a zinc-rich Zn0.98Ga0.02O target. A pure phase single-crystalline ZGO thin film was obtained at a deposition temperature of 750 °C and an oxygen pressure of 1 × 10−2 Torr. The out-of-plane epitaxial relationship between the sapphire and ZGO thin film was obtained from φ-scan. The x-ray rocking curve of the ZGO thin film grown at 750 °C exhibits a full width at half maximum of ∼0.098°, which indicates a good crystalline phase and quality of the thin film. Core-level x-ray photoelectron spectroscopy of ZGO grown at 750 °C indicated that Zn and Ga were in the 2+ and 3+ oxidation states, respectively, and the atomic ratio of Zn/Ga was estimated to be ∼0.48 from the fitted values of Zn-2p3/2 and Ga-2p3/2. The high-resolution transmission electron microscopy images revealed a sharp interface with the thickness of the ZGO film of ∼265 nm, and the signature of minor secondary phases was observed. The bandgap of the ZGO film at different growth temperatures was calculated from the ultraviolet-diffuse reflectance spectroscopy spectra, and its value was obtained to be ∼5.08 eV for the 750 °C grown sample. The refractive index (n) and the extinction coefficient (k) were determined to be ∼1.94 and 0.023 from the ellipsometric data, respectively, and the real dielectric function (ɛr) was estimated to be ∼6.8 at energy 5 eV. The ultrawide bandgap and dielectric function of ZGO recommend its possible potential applications in deep-ultraviolet optoelectronic devices and high-power electronics. [ABSTRACT FROM AUTHOR]

We report the nonlinear dielectric properties of three triple-perovskite ruthenates: Ba 3 CoRu 2 O 9 , Ba 3 BiRu 2 O 9 , and Sr 3 CaRu 2 O 9. These compounds exhibit notable correlations among their spin, charge, lattice, and polar degrees of freedom. Ba 3 CoRu 2 O 9 displays a pronounced frequency-dependent relaxation in χ 2 , 3 just above the magnetoelastic transition, occurring around 100 K, followed by an abrupt loss of polarization within the ordered phase. In Ba 3 BiRu 2 O 9 , we encounter the possibility of multiple coexisting relaxation behaviors, indicating a complex phase strongly influenced by the spin-gap opening at 175 K. Lastly, Sr 3 CaRu 2 O 9 displays anomalies with strong dispersion effects close to its magnetic transitions, indicating a robust coupling between magnetic and dipolar orders in the system. These measurements highlight the significance of higher-order (hyper-)susceptibilities in providing profound insight into the dynamics of a system, offering information otherwise inaccessible through the linear polarization response alone. [ABSTRACT FROM AUTHOR]

To develop special insulating paper is of great significance to promote the service life of transformers. Using molecular simulation to guide the development of special insulating paper can greatly reduce the trial-and-error rate and waste of resources in traditional experiments. The effect of different types of polysilsesquioxane (POSS) on cellulose insulating paper was investigated by using molecular simulation. This paper investigated the thermal stability and mechanical properties and electrical characteristics of caged POSS, semi-caged POSS, and ladder-like POSS doped cellulose insulating paper. The results show that POSS with all types can enhance the performance of cellulose insulating paper, and ladder-like POSS possess the best modification effect. The glass transition temperature was increased by 58 K, and the bulk modulus, shear modulus, and elastic modulus of cellulose insulating paper doped with ladder-like POSS can improve up to 27.07%, 45.67%, and 41.28%, respectively. Meanwhile, the dielectric properties of ladder-like POSS modified insulating paper are also significantly improved. The findings of this paper propose a method for the preparation of ladder-like POSS modified insulating paper, which provides theoretical guidance for the experimental preparation of special insulating paper. [ABSTRACT FROM AUTHOR]

Based on the transport and polarization relaxation theories, the effects of hydrogen, fluorine, and chlorine atom passivation on the conductivity and dielectric properties of silicon carbide nanowires (SiCNWs) were numerically simulated. The results show that passivation can decrease the dark conductivity of SiCNWs and increase its ultraviolet photoconductivity. Among them, the photoconductivity of univalent (H) passivated SiCNWs is better than that of seven-valent (Cl, F) passivated SiCNWs. In terms of dielectric properties, the passivated SiCNWs exhibit a strong dielectric response in both deep ultraviolet and microwave regions. Hydrogen passivation SiCNWs produce the strongest dielectric response in deep ultraviolet, while fluorine passivation SiCNWs produce the strongest dielectric relaxation in the microwave band, which indicates that atomic passivation SiCNWs have a wide range of applications in ultraviolet optoelectronic devices and microwave absorption and shielding. [ABSTRACT FROM AUTHOR]

The dependence of the dielectric permittivity of ferroelectric materials on electric field magnitude impacts the performance of ferroelectric devices. In a ferroelectric generator, a shock wave travels through the ferroelectric element and depolarizes it, and surface charges are released from the element electrodes, resulting in the generation of a megawatt power level for several microseconds. The dielectric properties of the compressed and uncompressed zones of the ferroelectric element affect the generated voltage and energy. The results of previous studies indicate that the low-field dielectric permittivity of poled Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 (PZT 95/5) ferroelectrics in the uncompressed zone differs significantly from the high-field permittivity. Herein, the results are presented from the experimental investigation of the high-field permittivity of poled uncompressed PZT 95/5 ferroelectric ceramics and films, PZT 52/48 ferroelectric ceramics, and rhombohedral 0.27Pb(In1/2Nb1/2)O3–0.47Pb(Mg1/3Nb2/3)O3–0.26PbTiO3 (0.27PIN-PMN-0.26PT) and 0.68Pb(Mg1/3Nb2/3)O3–0.32PbTiO3 (0.68PMN-0.32PT) ferroelectric single crystals. The dependences of the permittivity on the electric field were determined using a pulsed electric field ranging from 0.1 to 10 kV/mm. The data indicate that the application of a pulsed high electric field results in a fourfold increase in the relative permittivity of PZT 95/5 ceramics and films over the small signal value (from 300 to 1200), and a threefold increase in the permittivity of single-domain [111]c cut and poled 0.27PIN-PMN-0.26PT crystals (from 700 to 2100), while a high electric field does not have a significant impact on the permittivity of PZT 52/48 ceramics or 0.27PIN-PMN-0.26PT and 0.68PMN-0.32PT crystals cut and poled in the domain engineered [001]c or [011]c direction. [ABSTRACT FROM AUTHOR]

Molecular simulations serve as indispensable tools for investigating the kinetics and elucidating the mechanism of hindered ion transport across nanoporous membranes. In particular, recent advancements in advanced sampling techniques have made it possible to access translocation timescales spanning several orders of magnitude. In our prior study [Shoemaker et al., J. Chem. Theory Comput. 18, 7142 (2022)], we identified significant finite size artifacts in simulations of pressure-driven hindered ion transport through nanoporous graphitic membranes. We introduced the ideal conductor model, which effectively corrects for such artifacts by assuming the feed to be an ideal conductor. In the present work, we introduce the ideal conductor dielectric model (Icdm), a generalization of our earlier model, which accounts for the dielectric properties of both the membrane and the filtrate. Using the Icdm model substantially enhances the agreement among corrected free energy profiles obtained from systems of varying sizes, with notable improvements observed in regions proximate to the pore exit. Moreover, the model has the capability to consider secondary ion passage events, including the transport of a co-ion subsequent to the traversal of a counter-ion, a feature that is absent in our original model. We also investigate the sensitivity of the new model to various implementation details. The Icdm model offers a universally applicable framework for addressing finite size artifacts in molecular simulations of ion transport. It stands as a significant advancement in our quest to use molecular simulations to comprehensively understand and manipulate ion transport processes through nanoporous membranes. [ABSTRACT FROM AUTHOR]

Size effect is a fundamental phenomenon in ferroelectric materials and grain size dependence of the dielectric and piezoelectric properties of BaTiO3 (BTO) ceramics has been observed. However, the dependence of flexoelectric response on grain size has not been reported, thus far. In this work, BTO ceramics with grain sizes ranging from 0.59 to 8.90 μm were prepared by a two-step sintering method. We found that with increasing grain size, the flexoelectric coefficient of BTO ceramics increases from less than 20 μC/m (grain size 0.59–0.69 μm) to more than 300 μC/m (grain size 8.90 μm), but the grain size dependence of the flexoelectric response is different from that of the dielectric and piezoelectric properties. Observation by piezoresponse force microscopy reveals that the surface regions of BTO ceramics are spontaneously polarized. Strong inhomogeneous strain is measured by grazing incidence x-ray diffraction and the resultant flexoelectric effect is enough to polarize the surface regions. Fitting of the flexoelectric data indicates that the grain size effect of the flexoelectric response can be well explained by the polarized surface layer mechanism. [ABSTRACT FROM AUTHOR]

The Adaptive Solvent-Scaling (AdSoS) scheme [J. Chem. Phys. 155 (2021) 094107] is an adaptive-resolution approach for performing simulations of a solute embedded in a fine-grained (FG) solvent region surrounded by a coarse-grained (CG) solvent region, with a continuous FG ↔ CG switching of the solvent resolution across a buffer layer. Instead of relying on a distinct CG solvent model, AdSoS is based on CG models defined by a dimensional scaling of the FG solvent by a factor s, accompanied by the s-dependent modulation of its mass and interaction parameters. The latter changes are designed to achieve an isomorphism between the dynamics of the FG and CG models, and to preserve the dispersive and dielectric solvation properties of the solvent with respect to a solute at FG resolution. As a result, the AdSoS scheme minimizes the thermodynamic mismatch between different regions of the adaptive-resolution system. The present article generalizes the scheme initially introduced for a pure atomic liquid in slab geometry to more practically relevant situations involving (i) a molecular dipolar solvent (e.g., water); (ii) a radial geometry (i.e., spherical rather than planar layers); and (iii) the inclusion of a solute (e.g., water molecule, dipeptide, ion, or ion pair). [ABSTRACT FROM AUTHOR]

This study intends to improve the dielectric properties of PMMA/PEG/SiO2/SiC nanostructures for use in flexible pressure sensors and electrical nanodevices. PMMA/PEG films and PMMA/PEG films doped with SiO2 and SiC NPs were created using a casting technique. The structural properties of PMMA/PEG/SiO2/SiC nanostructures were examined using FTIR and an optical microscope. The dielectric properties were assessed using an LCR meter across a frequency range from 100 Hz to 5 MHz. The analysis of the structural features of PMMA/PEG/SiO2/SiC nanostructures showed a significant presence of SiO2 and SiC nanoparticles in the PMMA/PEG material and strong integration between SiO2 and SiC nanoparticles and the PMMA/PEG matrix. The dielectric properties showed an increase in the dielectric parameters of PMMA/PEG as the concentration of SiO2-SiC NPs increased. The dielectric constant and AC electrical conductivity of PMMA/PEG rose by approximately 39% and 49%, respectively, with low dielectric loss values ranging from 0.14 to 0.275 at 100 Hz. These findings suggest that PMMA/PEG/SiO2/SiC nanostructures may be suitable for a variety of nanoelectronics applications. The dielectric properties of PMMA/PEG/SiO2/SiC nanostructures changed as the frequency increased. The structure and dielectric properties of the PMMA/PEG/SiO2/SiC nanostructures suggest they can be used in a variety of flexible nanoelectronics applications due to their low-cost, high-energy storage capability, and minimal energy loss. An investigation was conducted on the pressure sensor application of PMMA/PEG/SiO2/SiC nanostructures. The results indicated that the PMMA/PEG/SiO2/SiC nanostructures exhibit high sensitivity to pressure, exceptional flexibility, and strong environmental resilience in comparison to other sensors. [ABSTRACT FROM AUTHOR]

High Q·f value and temperature-stable MgF 2 -doped MgTi 1-x (Mn 1/3 Sb 2/3) x O 3 ceramics have been successfully prepared by the solid-state reaction method. Microwave dielectric properties and sintering performance of MgF 2 -doped MgTi 1-x (Mn 1/3 Sb 2/3) x O 3 ceramics were systematically investigated by the classic theory and the P-V-L theory. The results show that MgF 2 doping and complex cation (Mn 1/3 Sb 2/3)4+ substitution not only further reduces the sintering temperature of MgTiO 3 ceramics from 1400 °C to 1250 °C, but also effectively improves the quality factor from 110210 GHz to 228713 GHz and adjust the τf value from −53.55 ppm/°C to −20.42 ppm/°C. The ionicity, the bond valence and octahedral distortion confirmed that Ti/(Mn 1/3 Sb 2/3)-O bonds exert a greater influence on microwave dielectric properties than Mg-O bonds in MgTiO 3 ceramics, which provides a guide to further improve the microwave dielectric performances. The optimal microwave dielectric properties: ε r = 18.8 ± 0.28, Q·f = 228713 ± 2500 GHz (at 6.08 GHz), τ f = (−20.42 ± 1.1) ppm/°C were achieved for 3 wt% MgF 2 doped MgTi 0.99 (Mn 1/3 Sb 2/3) 0.01 O 3 ceramics sintered at 1250 °C. [ABSTRACT FROM AUTHOR]

In this experiment, we successfully synthesized NaCaY(WO 4) 3 ceramic by employing a traditional solid-state reaction method. Experimental results demonstrated that NaCaY(WO 4) 3 ceramic sintered at 925 °C exhibited excellent microwave dielectric properties with ε r = 10.74, Q × f = 46510 GHz, and τ f = −32.7 ppm/°C. In addition, the dielectric demonstrated excellent chemical compatibility with Ag electrodes, suggesting its potential application in LTCC devices. To address its poor temperature stability, we optimized the original NaCaY(WO 4) 3 ceramic by doping Li 2 CO 3 , ultimately obtaining the Li x Na (1- x) CaY(WO 4) 3 (x = 0∼0.3) ceramics. XRD analysis confirmed the tetragonal scheelite structure of this ceramic systems. Rietveld refinement and Raman spectroscopy analysis revealed that the inclusion of Li 2 CO 3 had no impact on the phase structure of this ceramic system. Furthermore, the P-V-L theory demonstrated that the W-O bond significantly contributed to the Q × f value of Li 0.3 Na 0.7 CaY(WO 4) 3 ceramics. With a sintering temperature of 900 °C, Li 0.3 Na 0.7 CaY(WO 4) 3 ceramics exhibited the optimal microwave dielectric properties of ε r = 11.29, Q × f = 19363 GHz, and τ f = −2.46 ppm/°C. This highly stable microwave dielectric ceramic holds potential for applications in 5G communications. [ABSTRACT FROM AUTHOR]

Bi 0.5 Na 0.5 TiO 3 -based ferroelectric ceramics have broad application prospects due to their excellent electrical properties and are considered to be one of the most promising functional materials to supersede lead-based materials. Here, 0.9Bi 0.5 Na 0.5 TiO 3 -0.1Bi 0.2 Sr 0.7 TiO 3 - x NaNbO 3 (BNT-BST- x NN) ternary lead-free ferroelectric ceramics were prepared, and the origin of their excellent dielectric properties was investigated in terms of phase boundary and domain structure. The introduction of NN led to a phase transition from the ferroelectric rhombohedral phase (R 3 c) to the relaxor tetragonal phase (P 4 bm), and the two phases coexisted in the BNT-BST- x NN ternary solid solution with x ranging from 0.06 to 0.2. Meanwhile, the macroscopic domain of BNT-BST was destroyed and replaced by highly active polar nano-regions (PNRs) of the P 4 bm phase, leading to an increase in local structural disorder and enhanced relaxor behavior. A dielectric constant (ε r) of ∼1765 (150 °C) with Δ ε / ε 150 °C less than 15 % over a broad range from 80 to 328 °C was achieved in the BNT-BST-0.15NN, and an excellent energy storage property (W rec = 3.3 J/cm3) was obtained under a low electric field (190 kV/cm). More specifically, the relationship among phase boundary, domain structure, and excellent electrical properties was achieved based on Rietveld refinements and the dielectric/ferroelectric characterizations. This work provides a deep insight into the phase evolution and its impact on the electrical properties of the BNT-based relaxor ferroelectrics. [ABSTRACT FROM AUTHOR]

Herein, MgO–12 % TiO 2 (w) ceramics with different contents of Bi 2 O 3 –CuO sintering aid were prepared using a solid-state method. The effects of the sintering aid content on the sintering temperature and the dielectric and mechanical properties of the ceramics were studied. The material was characterized using scanning electron microscopy and X-ray diffraction and Precision LCR tester and universal testing machine and Archimedes drainage method. When the Bi 2 O 3 –CuO content was less than 9 wt%, the ceramic sample has higher dielectric properties. When the Bi 2 O 3 –CuO content was greater than 9 wt%, the dielectric properties will deteriorate. This is because Bi 2 O 3 participates in the chemical reaction between MgO and TiO 2 , forming a high dielectric loss Bi 4 Ti 3 O 7 phase. At high temperatures, Cu2+ can easily change valence to Cu+, promoting oxygen vacancies and increasing dielectric loss in ceramic samples. The introduction of Bi 2 O 3 –CuO produces new MgTiO 3 , Mg 2 TiO 4 , and Bi 4 Ti 3 O 12 phases in the sample structure, resulting in a structure in which the MgO grains in the sample are surrounded by the new phases that appear around them. This structure fills the pores, increases density, enhances mechanical properties. The dielectric properties of the ceramics were the when the sintering temperature was 1050 °C, and the Bi 2 O 3 –CuO content was 3 wt%. The dielectric constant and dielectric loss were 11.19 and 1.17 × 10−4, respectively. The bending strength of the ceramic sample increased from 138.72 MPa to 179.64 MPa when the Bi 2 O 3 –CuO content was increased from 3 wt% to 15 wt%. The Bi 2 O 3 –CuO sintering aid enables MgO to be better applied in ceramic substrates. [ABSTRACT FROM AUTHOR]

The temperature coefficient of dielectric constant (τ ε) is a crucial parameter for assessing the performance stability of microwave devices operating under varying temperature conditions. In this study, polyphenylene oxide (PPO) resin was utilized as the matrix and six types of ceramics with distinct temperature coefficients of dielectric constant were employed as fillers. Six PPO-based composites were fabricated through twin-screw extrusion combined with hot pressing route. The dielectric properties of the ceramics and their influence on the dielectric properties of the composites, particularly the τ ε , were systematically investigated. The results revealed that all six types of composites exhibited dense structures and uniform filler distribution, with a relative density exceeding 98.0 % and a water absorption below 0.1 %. The dielectric constant and its temperature coefficient of the fillers had a more pronounced effect on the dielectric properties of the composites, compared to dielectric loss. The dielectric constants of the six types of composites aligned well with the theoretical values predicted by the effective medium theory. Reaching up to 9.7 (at 10 GHz). The dielectric loss ranged from 1.0 × 10−3 to 3.0 × 10−3. Notably, the PPO/Mg 0.95 Ca 0.05 TiO 3 composite substrate with a filler ratio of 40 vol% exhibited exceptional dielectric properties: ε r = 6.8, tg δ = 1.4 × 10−3, τ ε = −8.6 ppm/°C, highlighting its significant advantages for communication applications under varying temperature conditions. [ABSTRACT FROM AUTHOR]

In this study, NaMg 1- x Mn x (PO 3) 3 (0.00 ≤ x ≤ 0.0625) ceramics with low dielectric constant were prepared via the solid-state reaction method. The effects of Mn2+ substitution on the microstructure and dielectric properties (at microwave and terahertz frequencies) of the NaMg(PO 3) 3 ceramics were studied by means of the Rietveld refinement, morphology, and ionic polarizability analysis. It is obtained that the NaMg 0.0975 Mn 0.025 (PO 3) 3 ceramic sintered at 880 °C for 4 h exhibited optimal dielectric properties at microwave frequencies, where ε r = 4.585, Q × f = 48,313 GHz (@17.228 GHz), and τ f = −40.83 ppm/°C. The Q × f and τ f values were changed by 74.2 % and 27.8 %, as compared to the values of 27,728 GHz and −56.52 ppm/°C for the pure NaMg(PO 3) 3 ceramic, respectively. For terahertz frequencies (0.2–1.0 THz), the ε r values were decreased to 3.79–3.98, and the tan δ values were between 0.0203 and 0.1152. All the experimental results indicate that this system exhibits great potentials both at microwave and terahertz frequencies. [ABSTRACT FROM AUTHOR]

The impact of tin (Sn4+) doping on sodium yttrium copper titanate (Na 0.5 Y 0.5 Cu 3 Ti 4 O 12) ceramics, prepared using a conventional mixed-oxide route, was thoroughly investigated in terms of microstructure, dielectric properties, electrical response, non-linear behaviors, and humidity-sensing characteristics. All sintered ceramics showed a dense micro-structure and a pure Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 phase without any secondary phases. The doped Na 0.5 Y 0.5 Cu 3 Ti 4−x Sn x O 12 ceramics, with x = 0.05, demonstrated excellent dielectric properties, including a low dielectric loss tangent (∼0.032) and a giant dielectric permittivity (∼1.8 × 104) across a wide temperature range. Sn4+ doping improved the non-linear behaviors at 25 °C in Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 , with a reduced dielectric loss tangent corresponding to an enhanced grain boundary (GB) response. The colossal dielectric response is attributed to the internal barrier layer capacitor model, which relates to the Schottky barrier height (Φ B) at the GBs. Notably, the Φ B values for the Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 ceramic increased with Sn4+ ion doping. Additionally, an in-depth study of the humidity-sensing properties of the Sn4+-doped Na 0.5 Y 0.5 Cu 3 Ti 4 O 12 material revealed that the capacitance at 1 kHz increased with increasing relative humidity levels, from 30 % to 90 %, suggesting potential applications in humidity-sensing technologies. [ABSTRACT FROM AUTHOR]

To reduce the dielectric loss of MXene/PVDF composites near the percolation threshold, a MnO 2 /MXene hybrid structure was successfully synthesized via an ultrasonic-assisted solution process, and MnO 2 /MXene/PVDF composite films were prepared by a solution casting method. The effects of different amounts of MnO 2 nanorods on the microstructure, thermal stability, dielectric properties and mechanical properties of the composite films were investigated. At 1 kHz, the dielectric constant of 7 wt% MnO 2 /MXene/PVDF is 37.3, and the dielectric loss is as low as 0.05. The electric modulus curve, Nyquist curve and equivalent analog circuit of the composites revealed strong interface polarization and microcapacitance effects in the composites. In addition, the composite films exhibit excellent mechanical properties, and the storage modulus of the composite film loaded with 10 wt% MnO 2 is 1990.5 MPa, which is 3.44 times that of pure PVDF. This study confirms that incorporating MnO 2 nanorods into MXene/PVDF composites is an effective approach for fabricating high-performance dielectric composites. [ABSTRACT FROM AUTHOR]

Sample of sodium-potassium tantalate (Na0.5K0.5TaO3) system was examined and frequency dependence of dielectric constant was studied in the frequency range from 0.01 MHz to 10 MHz, at varying temperature from 20 °C to 523 °C. With increasing frequency, thedielectric constant was found decreasing, which indicate relaxational behavior of the diploes in this system. With varying temperature, sample was observed to follow Curie-Weiss law with dielectric constant being minimum at the Curie temperature. [ABSTRACT FROM AUTHOR]

Fly ash cenospheres serve as an inexpensive filler for various composites. Coating their surface with metal significantly alters the properties of the resulting composites. In this study, aluminosilicate cenospheres receive a copper coating using a plasma method with magnetron sputtering. Based on these copper-coated cenospheres, composites are created, and their dielectric properties are investigated in a parallel plate capacitor cell under isotropic pressures ranging from 1 to 75 atm. Composites based on pure fly ash cenospheres exhibit pressure-invariant properties, including the dielectric constant and loss factor. However, for composites based on copper-coated fly ash cenospheres, an abrupt increase in electrical conductivity is observed as the pressure increases. Interestingly, significant changes in electrodynamics characteristics are not detected under the influence of anisotropic stress. The methodology tested in this work can be utilized for creating smart materials based on cenospheres. [ABSTRACT FROM AUTHOR]

In the present work, flexible Potassium Sodium Niobate - Polyvinyledene Fluoride (KNN-PVDF) composite sheets have been developed and utilized for the realization of a highly efficient pyroelectric energy harvester. KNN-PVDF composite sheets with varying the weight % of KNN (10–50 %) have been synthesized using solution casting method. The influence of KNN (Potassium Sodium Niobate) on the structural, morphological, and dielectric properties of PVDF has been investigated. The highest value of pyroelectric coefficient of 14.7 x 10 −4 Cm −2K−1 has been obtained for the flexible sheets of 30 % KNN-PVDF composite with change in temperature. It has been also observed from the ferroelectric studies that a high value of saturation polarization of 1.44 μC/cm2 is obtained at the applied bias of 5 V and 50 Hz frequency due to the presence of 30 % KNN in the KNN-PVDF composite sheets. The obtained results show the potential application of non-toxic, lead free KNN-PVDF composite sheets for thermal energy harvesting applications utilizing pyroelectric effect. [ABSTRACT FROM AUTHOR]

Strong absorption and large bandwidth are two contributors to material's electromagnetic wave absorbing performance. While spinel ferrite materials have garnered extensive attention in the realm of microwave absorption, their relatively low conductivity remains a practical challenge. In this work, NiCo 2-x Fe x O 4 (x = 0, 0.04, 0.06 and 0.08) precursor was prepared by hydrothermal and after-sintered method. It was found that Fe doping exhibit excellent EM absorption properties. Specially, when the Fe content is 0.08, the maximum reflection loss −48.90 dB at 15.40 GHz and the maximum effective bandwidth 4.20 GHz are achieved. More importantly, the absorption frequency can be broadened from Ku to C band even to S band with proper adjusting Fe content. Doping with Fe enhances conduction loss and make a significant contribution to dielectric loss, as a result, the impedance matching degree of the Fe-NiCo 2 O 4 composite is influenced by the synergistic effect of its dielectric and magnetic properties. This work provides a simple way for enhancing the microwave absorption capabilities of ferrite materials and provides insight into understanding conduction loss in microwave absorption. [ABSTRACT FROM AUTHOR]

In contrast to lead-based materials, lead-free ceramics Ba 0.85 Ca 0.15 Zr 0.10 Ti 0.90 O 3 (BCZT) offer outstanding dielectric, ferroelectric, and piezoelectric properties. A novel sonochemical method is employed to synthesize BCZT at low temperatures. The impact of high-energy acoustic waves reduces the calcination temperature to 600 °C, which is 300–400 °C lower than the already reported values. The samples are further sintered at different temperatures. The BCZT shows good dielectric properties (ε r ∼3000 and tanδ ∼0.075 at 1 kHz) at room temperature. X-ray diffraction analysis shows the co-existence of tetragonal and orthorhombic phases. Further, the scaling behavior is studied for domain dynamics in the sample. A three-stage polarization reversal mechanism is observed in BCZT ceramics. From the systematic study of the domain reversal mechanism, BCZT appears to be a promising candidate for sensors and actuator applications. [ABSTRACT FROM AUTHOR]

Ceramics of Li 2 Mg 2 GaTi 2 O 8 F (LMGTOF) were prepared by the traditional solid-state method. XRD and TEM results confirmed that a single phase of Li 2 Mg 2 GaTi 2 O 8 F, with an Fd-3m space group and a cubic spinel structure, was formed by the ceramics. It was shown by the results that the lattice parameters of the ceramics at 1050 °C were measured as a = b = c = 8.36576 Å, with a volume of V = 585.485549 Å3. Furthermore, it was observed through the analysis of the Raman peak at 718 cm−1 that an inverse relationship was exhibited between the Raman shift and ε r. Similarly, an opposing trend was also demonstrated between the Q × f value and FWHM. By bond valence analysis, it was shown that Mg2+, Ga3+, and Ti4+ ions were in a "rattling" state, and the large positive deviation between ε corr and ε theo was attributed to the strong "rattling" effect induced by the cations. At 1050 °C, the best microwave dielectric properties (ε r = 14.58, Q × f = 76,689 GHz, and τ f = −52 ppm/°C) were exhibited by LMGTOF ceramics. [ABSTRACT FROM AUTHOR]

In this paper, the tape casting method was used to prepare BST (Barium Strontium Titanate) thin films and the effect of combining cold sintering and reaction sintering processes on the properties of BST sheets was explored. A comparison was made between cold sintering and direct BST sintering combined. The combined process yielded high-density BST sheets with significantly improved dielectric properties (the resulting BST sheets displayed a low dielectric loss of less than 0.02 with a dielectric constant of 720) at a reduced sintering temperature of 950 °C. The underlying mechanisms for this enhanced performance are explored through structural and sintering analysis. [ABSTRACT FROM AUTHOR]

SrTiO 3 ceramic samples were successfully prepared using an innovative approach that combined ion implantation technique with the reductive-reoxidation sintering method. SrTiO 3 ceramics were reductively sintered in N 2 and H 2 atmosphere, and Cu ion implanted, followed by thermal oxidation treatment in air. Experimental results demonstrate a notable reduction in dielectric loss while achieving a colossal permittivity (ε = 41,444 at 1 kHz, tanδ = 0.054 at 1 kHz). The phase structure, micromorphology, element valence state, dielectric properties and AC impedance spectrum characteristics of SrTiO 3 ceramic materials were studied, and the mechanism of dielectric properties was explained using the Internal Barrier Layer Capacitor (IBLC) effects. Research results show that Cu ion implantation, oxygen vacancies at ceramic grain boundaries, and oxygen adsorption during reoxidation thermal treatment play a key role in reducing the dielectric loss of the material. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is believed to be a rather promising cable insulating material for high‐capacity electric power system with low carbon emission due to its decent thermo‐resistance and recyclable nature. In this paper, a new dually chemical grafting modification strategy by methyl acrylate (MA) and acrylic acid (AA) is put forward to tailor the charge transportation behavior in PP, thus further enhancing the electrical properties. Experimental results indicate that the dually grafted PP with 2.3 weight percent (wt%) MA and 1.9 wt% AA shows enhanced volume resistivity and electrical breakdown strength than pure PP, and the space charge injection is significantly suppressed. This work further adopts thermally stimulated depolarization current (TSDC) test and computational analysis based on density functional theory (DFT) to reveal the mechanism of enhancement. The analysis shows that grafted chemical groups can introduce quantities of deep traps and electrostatic potential wells which are strongly correlated with the carbonyl group and would hinder the charge transportation thus improving the electrical insulating performances of PP. This work would provide a new route of PP‐based dually grafting modification for the development of high‐voltage cable insulation. [ABSTRACT FROM AUTHOR]

The optical, photoluminescence, and electrical properties of Poly(Z)-PTI and Poly(E)-PTI, two Poly-Pyrrol-Thiazol-Imine polymers with comparable chemical structures but distinct configurations, were examined. Using the dip-casting method, polymer films were deposited on ITO substrates. UV-VIS spectroscopy revealed that both polymers diverged between 500 and 800 nm, showing the impact of molecular arrangement, but showed similar absorption behavior for wavelengths shorter than 500 nm. For Poly(Z)-PTI, the direct optical energy gaps were 2.06 eV, while for Poly(E)-PTI, they were 1.78 eV. Poly(Z)-PTI displayed an emission peak at 610 nm (red) according to laser photoluminescence spectra, while Poly(E)-PTI peaked at 563 nm (green-yellow). The capacitance behavior was revealed by electrochemical impedance spectroscopy. Nyquist plots suggested an equivalent circuit model of Rs (CRct)(QR)(CR) for both polymers, and the relaxation times were 15.9 ns for Poly(Z)-PTI and 89.5 ns for Poly(E)-PTI. The Mott-Schottky analysis verified the n-type conductivity, revealing 2.18 × 1016 cm− 3 carrier densities for Poly(Z)-PTI and 1.78 × 1016 cm− 3 for Poly(E)-PTI. At lower frequencies, both polymers exhibited limited conductivity and large dielectric constants. Insights into the possible uses of Poly-Pyrrol-Thiazol-Imine polymers in electrical and optoelectronic devices are provided by this study, which emphasizes the influence of molecular configuration on these polymers' characteristics. [ABSTRACT FROM AUTHOR]

Novel spinel-type Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics were prepared by the solid-state method. Rietveld refinement revealed that the Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics possess a cubic spinel structure with the F d 3 ‾ m (227) space group. Raman spectrum analysis indicated that the Q × f and FWHM of ceramics exhibit an inverse relationship. According to the P-V-L theory, the Ti-O bond has the highest percentage of contribution to both of bond ionicity and lattice energy, indicating a significant impact on ε r and Q × f , respectively. The Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics showed the best microwave dielectric properties (ε r = 15.72, Q × f = 69,633 GHz, and τ f = −20 ppm/°C), sintering at an optimum temperature of 1200 °C. Additionally, a dielectric resonance antenna, on the basis of Li 2 Mg 2 Ga 2 Ti 3 O 12 ceramics was designed and simulated. [ABSTRACT FROM AUTHOR]

This paper presents an investigation into the structural, magnetic, and dielectric characteristics of BaFe12-xYxO19 (x = 0.0, 0.2, 0.4, 0.6) nanoparticles (NPs) produced by the sol-gel method at 800, 900, 1000, 1100 °C annealing. Rietveld refinement analysis shows that the lattice parameter ratio (c/a) lies within the range of 3.93–3.96 provides the confirmation of M type hexaferrite with space group P 6 3 / mmc. The average crystallite size for BaFe 12 O 19 is found to decrease (53.0–23.4 nm) with increasing annealing temperature while for doped BaFe 12-x Y x O 19 it is increased from 30.7 to 96.2 nm. The magnetization found to decrease (82–17 emu/g) with Y3+ content for 800 and 900 °C annealing. However, for 1000 and 1100 °C annealing the magnetization increases and reaches to maximum 100.2 emu/g for x = 0.2 at 1100 °C annealing. The site preference of the Fe3+ ions is responsible to change the value of magnetization. The coercivity of undoped BaFe 12 O 19 varies from 4039 to 2028 with doping content. However, maximum coercivity 4586 Oe is found for x = 0.4 at 900 °C. The dielectric function is found to vary with annealing temperature and Y content as well. The wide range of magnetic properties (soft and hard magnetic) can be used in data storage, spintronic and microwave device applications. [ABSTRACT FROM AUTHOR]

Polymer-based ferroelectric composites, particularly those containing Poly (vinylidene fluoride) (PVDF), have emerged as preferred materials for flexible electronics and sensors owing to their excellent electro-mechanical attributes and ease of fabrication. The efficacy of PVDF composites is significantly influenced by the fillers and the proportion of the β-phase present. This research details the synthesis of La 0.7 Ba 0.3 MnO 3 (LBMO) particles via solid-state reaction, surface-functionalized with acetic acid, and subsequently introduced as nucleating agents into Poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) to fabricate LBMO/P(VDF-HFP) composite membranes. The LBMO fillers before modification significantly increased the β-phase content from 32.7 % to 87.8 % in 5 wt% unmodified LBMO/P(VDF-HFP) membranes. After modification, the hydroxyl groups attached to acetic acid-modified LBMO form hydrogen bonds with -CF 2 groups in P(VDF-HFP), inducing the formation of the β phase while enhancing macroscopic polarization and piezoelectricity. At a 7.5 wt% acetate-modified LBMO doping level, the composite membrane exhibits a β-phase content of 64.5 %, but concurrently enhancing the film's dielectric properties. At 103 Hz, the dielectric constant of 5 wt% modified LBMO/P(VDF-HFP) membrane increases to 24.8, with a minimal rise in dielectric loss from 0.0293 to 0.0314. Moreover, under a 10 N compressive load at 1 Hz, the 5 wt% modified LBMO/P(VDF-HFP) composite achieves an open-circuit voltage of 4.3 V. These improved dielectric and piezoelectric properties indicate the composite's suitability for energy harvesting applications. [ABSTRACT FROM AUTHOR]

BaIn 2 O 4 ceramics with the monoclinic crystal system of the P 2 1 / c space group were synthesized using a solid-state reaction method. The sample sintered at 1250 °C exhibits a relative density (94.3 %) and the following microwave dielectric properties: ε r = 16.3, Q × f = 49,500 GHz, τ f = −73.1 ppm/°C. The bond valence results shows that the deviation of permittivity (24.9 %) between the experimental (ε r = 16.3) and calculated values (ε r C-M = 13.05) obtained using the Clausius−Mosotti equation may be ascribed to the rattling effect of Ba2+ and In3+. Compared with orthorhombic CaIn 2 O 4 and SrIn 2 O 4 ceramics, BaIn 2 O 4 ceramics have lower Q × f values possibly because of the intrinsic loss caused by nonharmonic lattice vibration. The E dc value (0.43 eV) of BaIn 2 O 4 demonstrates that the defects are caused by the single ionized oxygen vacancies. The intrinsic ε r (14.7) and Q × f (105,600 GHz) values of the BaIn 2 O 4 ceramic was inferred through infrared reflectivity spectroscopy. All results demonstrate that the dielectric properties are affected not only by density, ionic polarizability, and rattling effect of cations, but also by the crystal system, and particularly the intrinsic factors. [ABSTRACT FROM AUTHOR]

We study experimentally and theoretically the influence of size effects and structural factors on the dielectric and ferroelectric properties of the dense ferroelectric composites. The composites have the form of the tape-casted films with 28 vol% of nanosized or submicron BaTiO 3 particles dispersed in the polyvinyl butyral. We measured and analyzed the temperature dependences of the capacitance and dielectric losses in the temperature range (−200 – +200)oC and frequency range (102–105) Hz. The nonmonotonic temperature dependences of dielectric permittivity of the studied composite films have a wide plateau-like maxima located between 80oС and 160oС, in contrast to the relatively sharp maximum near the Curie temperature (∼124oC) observed in the fine-grained and coarse-grained ceramics, sintered from the same nanosized or submicron BaTiO 3 particles at 1250oC. The shift of the dielectric permittivity and losses maxima (in more than 40oC) and their strong frequency dispersion do not agree with the behavior expected for the systems with a weak interaction between ferroelectric particles and a polymeric matrix. In contrast, we reveal the relaxor-like behavior of the composite dielectric response. To explain the observed results, we propose the analytical model, which considers the strong dipole-dipole cross-interaction of the BaTiO 3 particles in the dense nanocomposite. The analytical model is corroborated by the structural studies of the BaTiO 3 nanosized and submicron particles by X-ray phase analysis and static 137Ba NMR spectra, as well as by the finite element modelling of the composite polar properties, which confirms the strong cross-interactions between the dipole moments of single-domain nanoparticles and/or between the domain walls of different submicron polydomain particles. The obtained results may be useful for development of cheap and flexible lead-free dense ferroelectric nanocomposites with relaxor-like behavior of the dielectric response, which are promising for non-volatile memory and energy-saving elements, modulators, electrical converters and piezoresistive elements. [ABSTRACT FROM AUTHOR]

TiO 2 -based colossal dielectric ceramics have emerged as a prominent research focus in recent years. However, their further applications have been constrained by several key limitations, including the requirement of high sintering temperature (>1400 °C), relatively high dielectric loss (>0.05, 1 kHz), and temperature stability (<200 °C). This study reports rutile (In 0.5 Ta 0.5) 0.1 Ti 0.87 O 1.88 F 0.12 ceramics at 1220 °C sintering using 12 % InF 3 as the acceptor In3+ source, which exhibits a colossal dielectric constant (1.1 × 105) and an ultra-low dielectric loss (0.0071) at 1 kHz and room temperature, even loss values below 0.04 (20 Hz - 100 kHz). Notably, the thermal stabilities (10 kHz, 100 kHz) simultaneously satisfy X9E (Δε r /ε 25 °C ≤ ±4.7 %) above 300 °C. F − not only supplies electrons to enhance the semiconductivity of grains, but also decreases the oxygen vacancy and average grain size (270 ± 12.53 nm) to improve grain boundaries resistances, which reduces dielectric loss and enhances frequency and temperature stabilities. As a result, the dielectric mechanism is mainly related to internal barrier layer capacitor (IBLC) and high grain boundary resistance. Therefore, this strategy provides a creative design for developing TiO 2 -based ceramics. [ABSTRACT FROM AUTHOR]

The lead metaniobate (PbNb 2 O 6 , PN) with high Curie temperature is widely used to fabricate transducer for high-temperature application up to 300 °C. However, evident dielectric anomalies and direct-current resistivity degradation were experimentally observed in PN-based ceramics at high temperature, which may significantly restrict the working temperature range for well logging application. When the sample was heat-treated at 260 °C for 3 h in silicon oil, the dc-resistivity of ceramics at 260 °C decreased from 3.8 × 108 to 1.0×107 Ω⋅cm, accompanied by 43 times increase in tan δ at 1 kHz. To investigate the cause of these phenomena, the in-situ piezoelectric, dielectric properties and dc-resistivity were systematically investigated in the samples subjected to heat-treatment at 260 °C in silicon oil. It is revealed that the porous structure of PN-based ceramics allows for the infiltration of silicon oil as a minor phase, and the accumulation of its decomposers within the pores would exert significant influence on the dielectric property and dc-resistivity of ceramics at elevated temperatures. However, the samples still demonstrate excellent thermal stability in piezoelectric property, with value of k t maintaining 0.39 at 260 °C in oil. In addition, the low Q m is not the intrinsic property of PN ceramics, but rather related to the phase transition of silicon oil within pores of ceramics, as indicated by the increase in Q m from 47 to 80 after heat-treatment in air. [ABSTRACT FROM AUTHOR]