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Polymers with a low dielectric constant (Dk) are promising materials for high-speed communication networks, which demand exceptional thermal stability, ultralow Dk and dissipation factor, and minimum moisture absorption. In this paper, we prepared a series of novel low-Dk polyimide films containing an MCM-41-type amino-functionalized mesoporous silica (AMS) via in situ polymerization and subsequent thermal imidization and investigated their morphologies, thermal properties, frequency-dependent dielectric behaviors, and water permeabilities. Incorporating 6 wt.% AMS reduced the Dk at 1 MHz from 2.91 of the pristine fluorinated polyimide (FPI) to 2.67 of the AMS-grafted FPI (FPI-g-AMS), attributed to the free volume and low polarizability of fluorine moieties in the backbone and the incorporation of air voids within the mesoporous AMS particles. The FPI-g-AMS films presented a stable dissipation factor across a wide frequency range. Introducing a silane coupling agent increased the hydrophobicity of AMS surfaces, which inhibited the approaching of the water molecules, avoiding the hydrolysis of Si–O–Si bonds of the AMS pore walls. The increased tortuosity caused by the AMS particles also reduced water permeability. All the FPI-g-AMS films displayed excellent thermooxidative/thermomechanical stability, including a high 5% weight loss temperature (>531 °C), char residue at 800 °C (>51%), and glass transition temperature (>300 °C). [ABSTRACT FROM AUTHOR]

Although high permittivity of inorganic materials (possibly two orders larger than organic polymers) is theoretically considered as ideal triboelectric materials, their high leakage property and low contact potential difference with metal electrodes lead to failure to obtain high triboelectric charge density. Besides, the internal space charge accumulation as a result of their defect levels reduces the output charge density and causes dielectric loss or even dielectric breakdown under charge injection in charge‐excitation triboelectric nanogenerator (CE‐TENG). Herein, this study proposes high permittivity and low dielectric loss inorganic materials as triboelectric layers. In order to prevent charge injection passing through the surface of inorganic materials caused by air breakdown under charge excitation, an organic polymer is coated, which has high permittivity, big polarizability, none charge traps, and large work function difference with metal electrodes. After optimizing the high dielectric inorganic layer and the coated organic polymer layer, the output charge of CE‐TENG based on 1 mm PZT‐5H coated with P(VDF‐TrFE‐CFE) achieves 2.83 mC m−2, 6.5 times of CE‐TENG based on 1 mm PZT‐5H, breaking the historical record for inorganic material TENG. This work clarifies the material selection criteria for CE‐TENG and provides a deeper understanding of charge transfer mechanism of inorganic materials. [ABSTRACT FROM AUTHOR]

A first-principles theoretical approach to the effective dielectric permittivity of a nanocomposite, which contains nanoinclusions dispersed in a host dielectric enclosed between two parallel metallic electrodes, is developed. The inclusions are modeled by spheroids, and their response to the external electric field is found using the point dipole approximation and Green's function approach. As a result, besides the mutual interactions between the induced dipoles, the local field in the nanocomposite contains also a contribution from the dipole field reflected from the capacitor electrodes. It is shown that the nanocomposite dielectric permittivity is determined by an average inclusion polarizability density, and its dependence on the aspect ratio and orientations of inclusions is found analytically and investigated. The theoretical predictions derived in the paper are in excellent agreement with the available experimental data and can be used for a proper design of nanocomposite capacitors. [ABSTRACT FROM AUTHOR]

Recently, the investigation of the dielectric properties of glasses in the GHz frequency range has attracted great interest for use in printed circuit boards (PCBs) as a reinforcing material in the application of high-speed 5G/6G communications. In particular, glasses with low dielectric properties are a prerequisite for high-frequency applications. In this study, the GHz dielectric properties of alkali-free aluminoborosilicate glasses without and with La2O3 were analyzed using the Clausius–Mossotti equation where both the electronic and ionic polarizabilities contribute to the dielectric constant. The dielectric polarizability (αD) and oxide ion polarizability (αO2−) were calculated from the measured dielectric constant (εGHz) at 1 GHz and the glass density. The dielectric constants (εopt) at the optical frequencies and electronic polarizabilities (αe) of the glasses were calculated from the refractive index measured at 633 nm and the glass density. The εGHz values were found to be significantly higher than the εopt values in both series of glasses, due to the ionic polarizability (αi), which contributes additionally to the εGHz. The lower dielectric constants of the La2O3-incoporated glasses than that of the reference glass without La2O3 may be due to the lower ionic polarizability originated from the incorporation of the high cation field strength of the La3+ ions. [ABSTRACT FROM AUTHOR]

NaNbO3‐based antiferroelectric ceramics are promising candidates for high‐performance energy storage capacitors due to their environmental friendliness and low cost despite their current energy storage properties being inferior to those of their lead‐based and AgNbO3‐based counterparts. Typically, the antiferroelectric phase in NaNbO3 ceramics is not stable and the characteristic double hysteresis loops are seldom observed. In this work, the antiferroelectricity was improved by reducing the polarizability, resulting in well‐developed double hysteresis loops in 0.94NaNbO3–0.06(K0.5Bi0.5)SnO3 ceramics. To further improve the energy storage properties, defect engineering was performed for 0.94NaNbO3–0.06(K0.5Bi0.5)SnO3 by substituting Na+ with La3+ and introducing Nb vacancies. As a result, the stability of the field‐induced ferroelectric phase was reduced, and the energy storage properties were enhanced. The strategy of combining polarizability design and defect engineering can be a promising approach for optimizing NaNbO3‐based antiferroelectric ceramics. [ABSTRACT FROM AUTHOR]

Catalan's SPPN, a measure of solvent polarity/polarizability has been analysed in terms of molecular properties derived from computational chemistry. The results show that SPPN correlates positively with the molecular dipole moment and quadrupolar amplitude and negatively with the molecular polarizability. These correlations are shared with Kamet and Taft's π* and Reichardt and Dimroth's ET(30). Thus, one can associate the solvent polarity with non-specific interactions involving the permanent charges on solvent molecules. It is also noted that the opposite correlations, all three parameters increasing with increasing solvent polarity but decreasing with increasing solvent polarizability, creates an ambiguity in their use, for example, in linear free energy relationships. [ABSTRACT FROM AUTHOR]

Context: Organic semiconductors (OSCs) have attracted a great deal of interest in recent days. There are various types of OSCs, among which small molecules have various inherent benefits. Further research is needed to advance this new kind of material because the field is still developing, and the current focus is on creating small molecules that exist naturally for OSCs. OSCs with nonlinear optical (NLO) characteristics offer a significant advantage over others. Thus, this study theoretically investigates naturally occurring anthraquinones such as chrysophanol and rhein as potential OSCs, as well as their NLO properties. The calculated properties include the ionization potential (IP), electron affinity (EA), and bandgap (Eg). The FMO energy levels together with the Eg, IP (8.17–8.53 eV), and EA (1.87–2.44 eV) suggest the semiconductor nature of the studied compounds. The calculated values of reorganization energy (λ) and transfer integrals (V) suggest the p-type character of both molecules. Rhein has the lowest λh (0.19 eV) and Eg (3.28 eV) and the highest Vh, predominantly because of its better p-type character. The polarizability increases due to the presence of an electron-withdrawing substituent, leading to better NLO performance for Rhein, which is supported by its lower LUMO and Eg values. Methods: The studied molecules were optimized with the DFT/B3LYP-GD3/6-31+G(d,p) method using Gaussian 16 software. The crystal structure was simulated with Materials Studio 7.0, and the V values were calculated with the ADF package. The CDD and DOS plots were obtained with the Multiwfn 3.8 program. [ABSTRACT FROM AUTHOR]

This article studies the electrostatic response of a two-dimensional dielectric half-ellipse. A semianalytical method is presented for solving the polarizability of a half-ellipse as a function of its relative permittivity. The polarizability depends on the direction of incident field, and therefore, it is written as a dyadic with two perpendicular components. These are called series and parallel polarizability, and they are solved separately. The solution requires a series expansion of the potential function, and the coefficients must be obtained numerically, through an inversion of a finite matrix equation. Numerical results are presented for the polarizability components of the half-ellipse as functions of its geometry and permittivity. [ABSTRACT FROM AUTHOR]

Context: The structural, electronic, non-linear optical (NLO) and spectral properties of Hf x Ti y O 2 (x + y) clusters with (x + y ≤ 6) have been studied under the influence of an external electric field using density functional theory (DFT). The effect of variation in the Hf:Ti ratio on different properties of clusters is investigated. The motivation to study Hf x Ti y O 2 (x + y) clusters lies in the fact that HfTiO thin films have wide applications in various optoelectronic and photovoltaic devices. So, it will be interesting to study the effect of electric field on Hf x Ti y O 2 (x + y) clusters with the variation in the number of Hf, Ti and O atoms. It is observed that out of all the clusters, Hf 4 Ti 1 O 10 and Hf 5 Ti 1 O 12 are the most stable clusters with high values of binding energy and HOMO-LUMO gap. The application of an external electric field on these most stable clusters distorts their geometry and their HOMO-LUMO gap decreases, dipole moment and polarizability increases as the electric field is increased from 0 a.u. to 340 x 10 - 4 a.u. The applied electric field increases the polar character of clusters due to electron cloud deformation and hence, increases the reactivity of the clusters, thus making these clusters suitable for electrocatalytic reactions. The electric field controlled high values of dielectric constant makes these clusters suitable to be used in the oxide layer of metal oxide semiconductor field effect transistors (MOSFETs) with better capacitance. Under the effect of an electric field, the absorption peaks of UV-VIS spectra gets red-shifted. Due to the tuning of absorption spectra from ultraviolet to visible region, Hf x Ti y O 2 (x + y) clusters can be thought of as a good replacement for TiO 2 in dye-sensitized solar cells (DSSCs). Methods: The computational study of Hf x Ti y O 2 (x + y) clusters has been performed using DFT. For the ground state of Hf x Ti y O 2 (x + y) clusters, the optimization and frequency calculations have been performed using hybrid B3LYP (Becke three-parameter exchange functional combined with Lee, Yang and Parr correlation functional) functional with LANL2DZ (Los Alamos National Laboratory effective core potentials with Double Zeta atomic set) basis set under hybrid-GGA (generalized gradient approximation). Optimization and frequency calculations have been performed in each case. The excited state calculations have been carried out within time-dependent DFT formalism for a total of 50 excited states. The computational chemistry software package Gaussian 16 along with its graphical interface Gaussview have been employed for the current study of Hf x Ti y O 2 (x + y) clusters. [ABSTRACT FROM AUTHOR]

High thermal conductivity polymeric dielectrics with advanced dielectric properties are urgently demanded in various applications. In this study, a series of thermoplastic polyesters containing different content of fluorine and mesogenic unit in main chains are synthesized utilizing polycondensation. The preferred orientation of liquid crystal can effectively inhibit phonon scattering, and the introduction of fluorine can reduce the polarizability of the polymer and increase the free volume. By introducing the biphenyl mesogenic unit and fluorine into the main chain, its thermal conductivity has been increased to 0.425 Wm−1k−1 from 0.183 Wm−1k−1(the polymer without liquid crystal element), which is 132% higher than that of the liquid crystal polymer without fluorine. In addition, the dielectric constant of polyester decreased to 2.97, and the dielectric loss drops to 8.74 × 10−4. The influence mechanism of two ways on its thermal and dielectric properties is explored. Good thermal conductivity and excellent dielectric properties make potential in the thermal management system and flexible electronics. [ABSTRACT FROM AUTHOR]

The synthesis of the nanosized multifunctional thin film provides new solutions for many technological issues and consider a great step for miniaturized technology. Toward these goals, AgSbTe 2 semi-nanocrystalline thin films of different thicknesses were synthesized by the thermal evaporation technique. The structural features were investigated by X-ray diffraction, and selected area electron diffraction (SAED) yielding a semi-nanocrystalline thin film of grain size ranging from 9.98 to 21.38 nm. The energy-dispersive X-ray spectroscopy (EDAX) verified the high purity and stoichiometry of the deposited films. For optoelectronic application, many optical parameters, including band gap (E g), Urbach energy (E u), Refractive index (n), dispersion energy (E d), electronic polarizability (α e), and interband transition strength (J CV) were extensively discussed. The optical band gap reduced from 1.41 to 1.04 eV upon increasing the thickness from 150 to 550 nm. The temperature dependence of the electrical resistivity (ρ) of nanosized thin film was measured and the activation energy was estimated and it was found that the resistivity increased up to 450 K asserting the semiconductor behavior of the films. As for diode application, The Ag/2D-MoS 2 /p-AgSbTe 2 (550 nm)/n-Si/Al heterostructure diode was constructed by thermal evaporation and all the diode parameters alongside conduction mechanism were studied in detail. AgSbTe 2 -based diode showed a low rectification ratio; however, the ideality factor (n) and zero bias barrier height (Φ b) had optimal values of about 1.40 and 0.75 at room temperature, respectively. [ABSTRACT FROM AUTHOR]

New interatomic potential energy and interaction-induced polarizability curves for two ground-state neon atoms were developed and used to predict the second density, acoustic, and dielectric virial coefficients and the dilute gas shear viscosity and thermal conductivity of neon at temperatures up to 5000 K. The potential energy curve is based on supermolecular coupled-cluster (CC) calculations at very high levels up to CC with single, double, triple, quadruple, and perturbative pentuple excitations [CCSDTQ(P)]. Scalar and spin–orbit relativistic effects, the diagonal Born–Oppenheimer correction, and retardation of the dispersion interactions were taken into account. The interaction-induced polarizability curve, which in this work is only needed for the calculation of the second dielectric virial coefficient, is based on supermolecular calculations at levels up to CCSDT and includes a correction for scalar relativistic effects. In addition to these first-principles calculations, highly accurate dielectric-constant gas thermometry (DCGT) datasets measured at temperatures from 24.5 to 200 K were analyzed to obtain the difference between the second density and dielectric virial coefficients with previously unattained accuracy. The agreement of the DCGT values with the ones resulting from the first-principles calculations is, despite some small systematic deviations, very satisfactory. Apart from this combination of two virial coefficients, the calculated thermophysical property values of this work are significantly more accurate than any available experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] The electrical double layer formed at the mineral/electrolyte interface is often modeled using mean-field approaches based on a continuum description of the solvent whose dielectric constant is assumed to decrease monotonically with decreasing distance to the surface. In contrast, molecular simulations show that the solvent polarizability oscillates near the surface similar to the water density profile – as shown previously, for example, by Bonthuis et al. (D.J. Bonthuis, S. Gekle, R.R. Netz, Dielectric Profile of Interfacial Water and its Effect on Double-Layer Capacitance, Phys Rev Lett 107(16) (2011) 166102). We showed that molecular and mesoscale pictures agree by spatially averaging the dielectric constant obtained from molecular dynamics simulations over the distances relevant to the mean-field representation. In addition, the values of capacitances used to describe the electrical double layer in Surface Complexation Models (SCMs) of the mineral/electrolyte interface can be estimated using molecularly informed spatially averaged dielectric constants and positions of hydration layers. First, we used molecular dynamics simulations to model the calcite 10 1 ¯ 4/electrolyte interface. Next, by using atomistic trajectories, we calculated the distance-dependent static dielectric constant and water density in the direction normal to the. Finally, we applied spatial compartmentalization consistent with the model of parallel-plate capacitors connected in series to estimate SCM capacitances. Computationally expensive simulations are required to determine the dielectric constant profile of interfacial water near the mineral surface. On the other hand, water density profiles are readily assessable from much shorter simulation trajectories. Our simulations confirmed that dielectric and water density oscillations at the interface are correlated. Here, we parametrized linear regression models to estimate the dielectric constant directly from the local water density. This is a significant computational shortcut compared to slowly converging calculations relying on total dipole moment fluctuations. The amplitude of the interfacial dielectric constant oscillation can exceed the dielectric constant of the bulk water, suggesting an ice-like frozen state, but only if there are no electrolyte ions. The interfacial accumulation of electrolyte ions causes a decrease in the dielectric constant due to the reduction of water density and re-orientation of water dipoles in ion hydration shells. Finally, we show how to use the computed dielectric properties to estimate SCM's capacitances. [ABSTRACT FROM AUTHOR]

Recent advances regarding the interplay between ab initio calculations and metrology are reviewed, with particular emphasis on gas-based techniques used for temperature and pressure measurements. Since roughly 2010, several thermophysical quantities – in particular, virial and transport coefficients – can be computed from first principles without uncontrolled approximations and with rigorously propagated uncertainties. In the case of helium, computational results have accuracies that exceed the best experimental data by at least one order of magnitude and are suitable to be used in primary metrology. The availability of ab initio virial and transport coefficients contributed to the recent SI definition of temperature by facilitating measurements of the Boltzmann constant with unprecedented accuracy. Presently, they enable the development of primary standards of thermodynamic temperature in the range 2.5–552 K and pressure up to 7 MPa using acoustic gas thermometry, dielectric constant gas thermometry, and refractive index gas thermometry. These approaches will be reviewed, highlighting the effect of first-principles data on their accuracy. The recent advances in electronic structure calculations that enabled highly accurate solutions for the many-body interaction potentials and polarizabilities of atoms – particularly helium – will be described, together with the subsequent computational methods, most often based on quantum statistical mechanics and its path-integral formulation, that provide thermophysical properties and their uncertainties. Similar approaches for molecular systems, and their applications, are briefly discussed. Current limitations and expected future lines of research are assessed. [ABSTRACT FROM AUTHOR]

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CO adsorbed to NaCl(100) exhibits perhaps the weakest possible coupling between the adsorbate and solid. It is, therefore, an ideal system to observe the influence of adsorbate–adsorbate interactions on infrared absorption. In this work, we report polarized FTIR absorption spectra of CO/NaCl(100) as a function of coverage (0.02 ≤ θ ≤ 1 ML), where the coverage has been quantitatively determined by temperature-programmed desorption and molecular beam dosing. We extend a previous semi-empirical model designed to describe the screening of the local electric field due to dipole–dipole interactions in a CO monolayer. The extended model applies to sub-monolayer coverages and describes properly the electric field of the absorbed radiation at the vacuum–substrate interface. Fitting this model to coverage-dependent IR absorption data allows us to derive the vibrational and electronic polarizabilities [χv = 0.0435(14) Å3, χe = 3.30(36) Å3] and the integrated absorption cross section of 2.51(8) × 10−17 cm/molecule for an isolated CO molecule adsorbed at the NaCl (100) surface. The determined integrated absorption cross section is substantially smaller than that of gas phase CO. [ABSTRACT FROM AUTHOR]

We present the derivation and implementation of complex, frequency-dependent polarizabilities for excited states using the algebraic– diagrammatic construction for the polarization propagator (ADC) and its intermediate state representation. Based on the complex polarizability, we evaluate C6 dispersion coefficients for excited states. The methodology is implemented up to third order in perturbation theory in the Python-driven adcc toolkit for the development and application of ADC methods. We exemplify the approach using illustrative model systems and compare it to results from other ab initio methods and from experiments. [ABSTRACT FROM AUTHOR]

The 2D-Raman-THz response in all possible time-orderings (Raman-THz-THz, THz-Raman-THz, and THz-THz-Raman) of amorphous water ice is calculated in two ways: from atomistic molecular dynamics simulations and with the help of a Feynman diagram model, the latter of which power-expands the potential energy surface and the dipole and polarizability surfaces up to leading order. Comparing both results allows one to dissect the 2D-Raman-THz response into contributions from mechanical anharmonicity, as well as electrical dipole and polarizability anharmonicities. Mechanical anharmonicity dominates the 2D-Raman-THz response of the hydrogen-bond stretching and hydrogen-bond bending bands of water, and dipole anharmonicity dominates that of the librational band, while the contribution of polarizability anharmonicity is comparably weak. A distinct echo of the hydrogen-bond stretching band is observed for the THz-Raman-THz pulse sequence, again dominated by mechanical anharmonicity. A peculiar mechanism is discussed, which is based on the coupling between the many normal modes within the hydrogen-bond stretching band and which will inevitably generate such an echo for an amorphous structure. [ABSTRACT FROM AUTHOR]

The molar absorption coefficients of spherical InP, ZnS, and InP(core)/ZnS(shell) nanoparticles have been calculated from the complex permittivities of the corresponding bulk semiconductors. The results are valid in the short-wavelength region of the absorption spectrum, where the quantum size effect is insignificant. For the imaginary part of the polarizability of core/shell nanoparticles, a formula has been obtained that is convenient for calculations in real numbers. [ABSTRACT FROM AUTHOR]

Quantum chemical calculations of 4-(5-methyl-3-phenylbenzofuran-2-yl)-6-chloro-chromen-2-one (MPBClC) fluorescent molecule have been carried out using Gaussian 16 software. They exhibit antimicrobial properties and have shown promising anti-fungal activity. Semi-empirical and Hartree-fock method are the convenient tools to study optimized geometry and ground state dipole moment. The proton transfer within the selected donor-acceptor depicting large energy of stabilization for the molecule is given by NBO analysis. NLO properties are used to determine the polarizability and hyper polarizability of the molecules. Various photophysical properties were studied from spectroscopic analysis of UV-Visible, NMR, IR and Raman spectra using DFT method at 6-31G/B3LYP basis set. UV-Visible spectra obtained from TD-DFT method are parameters like absorption maxima, oscillator strength and excited state energies. The excited state dipole moment obtained from TD-DFT method is higher than the ground state dipole moment. Absorption maxima of molecules observed is around 330 nm-370 nm. IR and Raman vibrational spectroscopy have been studied in the regions 3500-50 cm-1. The 1H and 13C NMR shielding values were evaluated from NMR spectra using GIAO method. 1H NMR shielding values were higher than 13C NMR. Molecular orbital viz., HOMO-LUMO and ESP maps are useful for the study of charge transfer and charge distribution within the molecule. [ABSTRACT FROM AUTHOR]

Terahertz (THz) time-domain spectroscopy was used to study the optical properties of two series of oxyfluorosilicate (OFS) glasses. The experimentally measured refractive indices are analyzed by using the Clausius–Mossotti equation to retrieve information about polarizability of the glass. Compared with previously studied oxide-based glasses and chalcogenides, OFS glasses exhibit a balance of relatively low absorption coefficients (6–9 cm−1) and high refractive indices (2.9–3.7) at 0.5 THz. The value of 3.7 is the highest among silicate glasses reported to date and are comparable to those of La3+:chalcogenide glasses. The relatively high values of refractive indices have been attributed to the great increase of the glass polarizability in OFS glasses, which offsets the effect of an increase in molecular volume caused by multicomponent modification of the glass structure. Comparatively low THz absorption of OFS glasses is explained by the structural relaxation effect of fluorine, which effectively suppress the charge fluctuation in the glass structure. The high refractive index and low absorption loss properties of the present OFS glasses should be useful for quasi-optic components such as lens and waveguide devices application in the sub-THz and millimeter wave region. [ABSTRACT FROM AUTHOR]

This paper discusses and analyzes the quasistatic optimal plasmonic dipole resonance of a small dielectric particle embedded in a lossy surrounding medium. The optimal resonance at any given frequency is defined by the complex valued dielectric constant that maximizes the absorption of the particle under the quasistatic approximation and a passivity constraint. In particular, for an ellipsoid aligned along the exciting field, the optimal material property is given by the complex conjugate of the pole position associated with the polarizability of the particle. In this paper, we employ the classical Mie theory to analyze this approximation for spherical particles in a lossy surrounding medium. It turns out that the quasistatic optimal plasmonic resonance is valid, provided that the electrical size of the particle is sufficiently small at the same time as the external losses are sufficiently large. Hence, it is important to note that this approximation cannot be used for a lossless medium, and which is also obvious, since the quasistatic optimal dipole absorption becomes unbounded for this case. Moreover, it turns out that the optimal normalized absorption cross sectional area of the small dielectric sphere has a very subtle limiting behavior and is, in fact, unbounded even in full dynamics when both the electrical size and the exterior losses tend to zero at the same time. A detailed analysis is carried out to assess the validity of the quasistatic estimation of the optimal resonance, and numerical examples are included to illustrate the asymptotic results. [ABSTRACT FROM AUTHOR]

We theoretically investigate the optical force exerted on an isotropic particle illuminated by a superposition of plane waves. We derive explicit analytical expressions for the exerted force up to quadrupolar polarizabilities. Based on these analytical expressions, we demonstrate that an illumination consisting of two tilted plane waves can provide a full control on the optical force. In particular, optical pulling, pushing, and lateral forces can be obtained by the proper tuning of illumination parameters. Our findings might unlock multiple applications based on a deterministic control of the spatial motion of small particles. [ABSTRACT FROM AUTHOR]

A dielectric material is a particular type of insulator that does not conduct electricity but gets polarized when subjected to electricity, which is a crucial part of electronics such as cables, capacitors, displays, transformers, etc. Currently, synthesizing a nonpolar dielectric remains challenging. In this study, a method to make a high dielectric and nonpolar fluoropolymer and its nanocomposites based on cellulose nanocrystals (CNCs) by grafting it with nonpolar polymer 2,2,2‐trifluoroethyl methacrylate is reported. A high dielectric constant but nonpolar nanocellulose material is obtained for the first time. This material has an anisotropic arrangement of dipoles with a high polarizability effect, thereby displaying excellent dielectric properties (e.g., dielectric constant and loss: 8.59 and 0.017 at 10 kHz) and high stability (dielectric constant at 8.21 at 1 MHz). The dielectric material is miscible as an additive with other commercial fluoropolymer plastic, which demonstrates a high breakage voltage ranging from 4.6 to 9.2 kV/0.1 mm. When it is used as an interfacial layer in electrowetting display devices, it also demonstrated a low voltage driven and fast‐response effect. The excellent dielectric performances allow to develop more high‐performance dielectrics and electronics such as memories, sensors, actuators, wires, and film capacitors. [ABSTRACT FROM AUTHOR]

In the present work, we synthesized composites (1 − x) Bi0.9La0.1FeO3-(x) BaTiO3 with x = 0.05, 0.10, and 0.15 by solid-state technique. We studied their crystal structure, morphology, optical, electrical, and magnetic behavior. Crystal structure of the constituents of the composites and their presence in the composite was witnessed from the analysis of X-ray diffractograms by Rietveld refinement of the synthesized composites. Micrographs obtained from FESEM characterization technique revealed the non-homogeneous grain and grain boundaries with no foreign impurities. In addition, energy-dispersive X-ray diffraction analysis (EDAX) confirms the presence of all the integral elements of the composite. Optical bandgap of the order of ~ 2.19 eV was estimated from the analysis of diffuse reflectance UV–Vis spectroscopy (DRS). Temperature-dependent dielectric properties of the synthesized samples were measured at different constant frequency values in the temperature range from 100 to 350 °C. A gradual increase in dielectric constant from 180 °C was shown by all the samples. Corresponding to different applied constant field values, the polarizability vs. electric field loop (P–E loop) of all composites displays leakage. This behavior is attributed to the volatile nature of bismuth ferrite. Magnetization vs. magnetic field (M–H) hysteresis loop characteristics obtained at room temperature revealed the anti-ferromagnetic nature for pure Bi0.9La0.1FeO3. Further, weak ferromagnetic property becomes dominant as BaTiO3 content increased in the composite.Article title: Kindly check and confirm the edit made in the title.ok [ABSTRACT FROM AUTHOR]

The present work is devoted to the analysis of polarization effects in atomic systems of the argon type. Special attention is given to the manifestation of the polarizabilities of two particles in the density dependence of the dielectric permittivity of a system and its effective molecular polarizability. It is shown that the effective polarizability of a molecule in the liquid state of a system is mainly caused by deviation of the molecular distribution in the first coordination layer from the spherical one. Due to this, the atomic polarizability inherent to rarefied gas increases practically twice near the triple point. The interconnection between the atomic polarizability and the proper volume of an atom is discussed in detail. It is established that the optimal size of an atom follows from the kinematic shear viscosity measurements. • The analysis of previously ignored polarization effects in atomic systems such as argon. • The manifestation of two-particle polarizability depending on the dielectric constant of the system. • The deviation of the first molecular coordination layer from the spherical one determines the permittivity. • The approach can change the understanding of the dielectric properties of systems more complex than argon. [ABSTRACT FROM AUTHOR]

Due to the high polarizability of traditional flame retardants, it is difficult to meet the excellent dielectric properties and flame retardancy required for electronic packaging materials. Therefore, we have designed a novel linear polyphosphazene that can balance the dielectric properties and flame retardancy of bismaleimide (BMI) composites. Here, fluorinated aromatic ring structure with the large freedom volume is connected to the main chain of polydichlorophosphazene (PDCP) as a side group, resulting in multifunctional fluorinated linear polyphosphazene (PBTFP). Attributed to the excellent P/N/F combination flame retardant strategy, extremely low polarizability, and large molecular free volume, PBTFP simultaneously improves the dielectric properties and flame retardancy of the BMI composites, including UL-94 rating of V0, and a dielectric constant (D k) as low as 2.69. In addition, as an elastomer, PBTFP exhibits positive effects on improving the hydrophobicity and toughness of BMI. Therefore, through a simple affinity substitution reaction, we prepared a multifunctional fluorinated linear polyphosphazene modified BMI based electronic packaging substrate material that can be applied to 5G high-frequency communication. [Display omitted] [ABSTRACT FROM AUTHOR]

A theory of redox reactions involving electron transfer between a metal electrode and a polarizable molecule in solution is formulated. Both the existence of molecular polarizability and its ability to change due to electron transfer distinguish this problem from classical theories of interfacial electrochemistry. When the polarizability is different between the oxidized and reduced states, the statistics of thermal fluctuations driving the reactant over the activation barrier becomes non-Gaussian. The problem of electron transfer is formulated as crossing of two non-parabolic free energy surfaces. An analytical solution for these free energy surfaces is provided and the activation barrier of electrode electron transfer is given in terms of two reorganization energies corresponding to the oxidized and reduced states of the molecule in solution. The new non-Gaussian theory is, therefore, based on two theory parameters in contrast to one-parameter Marcus formulation for electrode reactions. The theory, which is consistent with the Nernst equation, predicts asymmetry between the cathodic and anodic branches of the electrode current. They show different slopes at small electrode overpotentials and become curved at larger overpotentials. However, the curvature of the Tafel plot is reduced compared to the Marcus-Hush model and approaches the empirical Butler-Volmer form with different transfer coefficients for the anodic and cathodic currents. [ABSTRACT FROM AUTHOR]

With the recent advances in experimental attosecond science, theoretical predictions of electron dynamics can now be validated against experiment. Time-dependent studies of the electron motion in molecules can be used to obtain information about electronic transitions and the interaction of the electrons with electromagnetic fields. Often, these approaches rely on single-excited wave functions. Presented here is a first attempt to evaluate the accuracy of the time-dependent configuration interaction method so that the optimal representation of the electronic wave function for time-dependent studies can be assessed. A quantifier is determined that can aid in finding this optimal representation. The approach is demonstrated on a variety of molecules that include both localized and intramolecular charge transfer electron excitations. Observables including excitation energies, dipole moments, strengths, and static polarizabilities are obtained from time-independent and time-dependent calculations and are compared to experimental data. In this way, a rigorous routine is developed by which the reliability and accuracy of the CI wave function can be assessed and which represents a first step to a more quantitative description of electron dynamics in molecules. Published by AIP Publishing. [ABSTRACT FROM AUTHOR]

The electronic structure, dipole moment (µ), average polarizability (< α >), anisotropie (Δα), first molecular hyperpolarizability (βmol), molar refractivity (κ) , HOMO energy (EHOMO), LUMO energy (ELUMO), energy gap (Egap), ionization potential (IP), electron affinity (EA), electronegativity (ς) , chemical potential (δ) , chemical hardness (ϑ) , chemical softness (σ) , and electrophilicity index (ω) , , total electronic energy (E0), zero point vibrational energy (zpve), thermal energy (E), Molar heat capacity at constant volume (CV), entropy (S), total electronic energy without Zero point correction (E1), total electronic energy with Zero point correction (E2), total electronic energy with thermal Energies (E3), total electronic energy with Enthalpies (E4), total electronic energy with thermal free Energies (E5), Volume (V), average Electric field (E), Polarization density (P), electric susceptibility (χ), relative dielectric constant (ɛr), dielectric constant (ɛ), refractive index (ɳ) and displacement vector (D) of doped and undoped pentacene and petracene have been determined by using Restricted Hartree–Fock (RHF), and Density Functional Theory (DFT) methods (B3LYP, WB97XD and BPBE) with the cc-PVDZ basis set. The aim of this work is to research new materials that can have applications in the fields of linear and nonlinear optics, electronics and optoelectronics. The results obtained from B3LYP, WB97XD and BPBE level show that the molecules are good semiconductor with very good optoelectronic properties and may have application in photonic, electronic, optoelectronics, organic light-emitting diode (OLEDs) and thin films. The large values of the refractive index (ɳ) and electric susceptibility (χ) of these molecules allow us to conclude that these molecules have good linear and nonlinear optical, electronic optoelectronic and photonic applications. [ABSTRACT FROM AUTHOR]

A theoretical investigation on neutral excitons confined to a mono-layer (ML) semiconductor transition metal dichalcogenide (TMDC) materials under the influence of elliptically deformed gate induced confining potential is presented. It has been shown that the anisotropy of the confinement induces the anisotropy of linear response of the system on in-plane external electric field. The linear response is expressed in terms of principal moments of the static dipole polarizability tensor. In this manner the direction-dependent polarizability of the system can be fully controlled by tuning the parameters of gate-induced confining potential. The components of the polarizability tensor are determined using finite-field method based on the exact diagonalization of the electron-hole Hamiltonian including confining potential, Coulomb electron-hole interaction and an external electric field, within effective mass approximation, close to the K-points of the first Brillouin zone of a single-layer MX 2 material. The useful scaling relations for energies and dipole polarizabilities as functions of material parameters have been found. The influence of the anisotropy of the confining potential on correlated behavior of charge distribution inside the neutral system has also been demonstrated. [ABSTRACT FROM AUTHOR]

The induced dipole and the classical Drude oscillator represent two major approaches for the explicit inclusion of electronic polarizability into force field-based molecular modeling and simulations. In this work, we explore the equivalency of these two models by comparing condensed phase properties computed using the Drude force field and a multipole and induced dipole (MPID) model. Presented is an approach to map the electrostatic model optimized in the context of the Drude force field onto the MPID model. Condensed phase simulations on water and 15 small model compounds show that without any reparametrization, the MPID model yields properties similar to the Drude force field with both models yielding satisfactory reproduction of a range of experimental values and quantum mechanical data. Our results illustrate that the Drude oscillator model and the point induced dipole model are different representations of essentially the same physical model. However, results indicate the presence of small differences between the use of atomic multipoles and off-center charge sites. Additionally, results on the use of dispersion particle mesh Ewald further support its utility for treating long-range Lennard Jones dispersion contributions in the context of polarizable force fields. The main motivation in demonstrating the transferability of parameters between the Drude and MPID models is that the more than 15 years of development of the Drude polarizable force field can now be used with MPID formalism without the need for dual-thermostat integrators nor selfconsistent iterations. This opens up a wide range of new methodological opportunities for polarizable models. [ABSTRACT FROM AUTHOR]

The electrostatic field in a nanocomposite represented by spherical nanoparticles (NPs) embedded into a dielectric between two parallel metallic electrodes is derived from first principles. The NPs are modeled by point dipoles which possess the polarizability of a sphere, and their image potential in the electrodes is found using a dyadic Green's function. The derived field is used to obtain the parameters which characterize the electrical breakdown in a nanocomposite capacitor. It is found, in particular, that for relatively low volume fractions of NPs, the breakdown voltage linearly decreases with the volume fraction, and the slope of this dependence is explicitly found in terms of the dielectric permittivities of the NPs and the dielectric host. The corresponding decrease in the maximum energy density accumulated in the capacitor is also determined. A comparison with the experimental data on the breakdown strength in polymer films doped with BaTiO 3 NPs available in the literature reveals a dominant role of the interface polarization at the NP-polymer interface and an existence of a nonferroelectric surface layer in NPs. This research provides a rigorous approach to the electrical breakdown phenomenon and can be used for a proper design of nanocomposite capacitors. [ABSTRACT FROM AUTHOR]

Despite quantum electrodynamics (QED) being one of the most stringently tested theories underpinning modern physics, recent precision atomic spectroscopy measurements have uncovered several small discrepancies between experiment and theory. One particularly powerful experimental observable that tests QED independently of traditional energy level measurements is the “tune-out” frequency, where the dynamic polarizability vanishes and the atom does not interact with applied laser light. In this work, we measure the tune-out frequency for the 23S1 state of helium between transitions to the 23P and 33P manifolds and compare it with new theoretical QED calculations. The experimentally determined value of 725,736,700(260) megahertz differs from theory [725,736,252(9) megahertz] by 1.7 times the measurement uncertainty and resolves both the QED contributions and retardation corrections. [ABSTRACT FROM AUTHOR]

[Display omitted] • BST thin films prepared at different oxygen partial pressures using PLD. • Microwave dielectric properties were estimated by fabricating a CPC structure and measured using on-wafer probing technique. • High microwave dielectric tunability was observed in the BST films deposited at higher oxygen pressure. Thin films of Ba 0.5 Sr 0.5 TiO 3 (BSTO) were pulsed laser deposited on platinized silicon substrates with varying oxygen pressure from 5 × 10−1 mbar to 5 × 10−6 mbar. A strong correlation between the oxygen partial pressure during the PLD process and the structural and microwave dielectric properties of the PLD-grown BSTO thin films is observed. The structural properties of the PLD-grown BSTO films were analyzed by XRD, Raman spectroscopy, FTIR spectroscopy, and XPS studies, and it is observed that oxygen vacancies are formed in low oxygen pressure deposited films. Dielectric studies at microwave frequencies show that high oxygen pressure deposited BSTO films show good microwave dielectric properties and crystallinity. At 1 GHz frequency, the BSTO film grown at 5 × 10−2 mbar oxygen pressure exhibits a dielectric constant ∼470 and dielectric loss ∼0.15. The oxygen vacancies change the nature of metal-oxide bonding (Ti-O bond), affect the polarizabilities, and, as a result, reduce the dielectric constant. A maximum dielectric tunability of 71 % is observed in microwave frequencies for the BSTO films grown at 5 × 10−2 mbar oxygen pressure. [ABSTRACT FROM AUTHOR]

Zinc chloride, ZnCl2, is intermediate between a strong and a fragile glass former. During computational simulations, it is therefore important to account for ion polarizability. This, together with the lack of suitable interatomic potential parameters, is the likely cause for the lack of modeling studies on ZnCl2 glass which contain a high degree of ZnCl4 tetrahedral units. Through using accurate interatomic potential parameters and applying the adiabatic core-shell model, the first fully tetrahedral model of ZnCl2 glass was obtained. The Cl-Zn-Cl bond angle of 109° reproduced the ideal tetrahedral bond angle, and the calculated total neutron and x-ray structure factors closely replicated experimental findings. While 86% of the ZnCl4 tetrahedral units were corner-sharing, 14% were found to be edgesharing. This led to two distinct contributions in both the Zn-Cl-Zn bond angle distribution and in the Zn···Zn nearest neighbour peaks being seen. These are not apparent in studies based on neutron diffraction. By comparing the intermediate glass former ZnCl2 to the strong glass former SiO2, marked differences in ring statistics became apparent. The Zn-Cl-Zn bond angle of around 110° enabled 3-membered rings to form in significant proportions. In contrast, 3-membered rings were only present in SiO2 glass as defects. By calculating the ZnCl2 and SiO2 partial structure factors, strong similarities became visible after scaling according to nearest neighbour distances. Although it was apparent that the main contributions to the first sharp diffraction peak (FSDP) came from cation-anion correlations, the relative scaling of the FSDP positions in ZnCl2 and SiO2 glass was not understood. [ABSTRACT FROM AUTHOR]

We report highly conductive and stable p-type phosphorus doped ZnO (PZO) thin films fabricated by dual ion beam sputtering and subsequent thermal annealing. Hall measurements established that the annealed PZO films were p-type, which were also confirmed by typical diode-like rectifying current-voltage (I-V) characteristics of the p-PZO/n-Si heterojunction. The maximum hole concentration was evaluated to be 8.62×1019 cm-3 with a resistivity of 0.066 Ω cm and a mobility of 1.08 cm2/V s at room temperature. The stability of the p-type conduction was verified by Hall measurement performed again after one year of thin film fabrication resulting in a hole concentration of 3.77×1019 cm-3. Spectroscopic ellipsometry was employed to determine the complex dielectric function (e = e1 + ie2) of p-type PZO films in the 1.2–6.4 eV energy range by a parameterized semiconductor oscillator model. Room temperature excitonic features were identified and the critical point energy was determined by second order derivative of imaginary part of dielectric function. The line shape analysis of e resulted in a red shift of the energy positions of the critical point with an increase in hole concentration. [ABSTRACT FROM AUTHOR]

The analytic hyperpolarizability and polarizability derivative with fractional occupation numbers are derived using Wigner's 2n + 1 rule. The formulation contains no terms that blow up for quasidegenerate systems. The density-functional tight-binding method is used for implementation, which makes it possible to compute these third-order derivatives for systems containing up to one thousand atoms within 8 h using 24 CPU cores. A comparison between analytic and numerical non-resonance Raman activity spectra indicates that the numerical differentiation approach can give a significant deviation unless the strength of perturbative electric field is carefully chosen. With extremely high electronic temperatures, the polarizability and hyperpolarizability should converge to zero. [ABSTRACT FROM AUTHOR]

Dipole polarizabilities were computed using density functional theory for silicon clusters over a broad range of sizes up to N = 147 atoms. The calculated total effective polarizabilities, which include contributions from permanent dipole moments of the clusters, are in very good agreement with recently measured values. We show that the permanent dipole contributions are most important for clusters in the intermediate size range and that the measured polarizabilities can be used to distinguish between energetically nearly degenerate cluster isomers at these sizes. We decompose the computed total polarizabilities α into the so-called dipole and charge transfer contributions, αp and αq, using a sitespecific analysis. When the per-atom values of these quantities are plotted against N-1/3, clear linear trends emerge that can be extrapolated to the large size limit (N-1/3 → 0), resulting in a value for α/N of 30.5 bohrs³/atom that is significantly larger than the per-atom polarizability of semiconducting bulk Si, 25.04 bohrs³/atom. This indicates that Si clusters possess a higher degree of metallicity than bulk Si, a conclusion that is consistent with the strong electrostatic screening of the cluster interiors made evident by the analysis of the calculated atomic polarizabilities. [ABSTRACT FROM AUTHOR]

The dependence of multipole moments and polarizabilities on external fields appears in many applications including biomolecular molecular mechanics, optical non-linearity, nanomaterial calculations, and the perturbation of spectroscopic signatures in atomic clocks. Over a wide range of distances, distributed multipole and polarizability potentials can be applied to obtain the variation of atom-centered atoms-in-molecules electric properties like bonding-quenched polarizability. For cylindrically symmetric charge distributions, we examine single-center and atom-centered effective polarization potentials in a non-relativistic approximation for Rydberg states. For ions, the multipole expansion is strongly origin-dependent, but we note that origin-independent invariants can be defined. The several families of invariants correspond to optimized representations differing by origin and number of terms. Among them, a representation at the center of dipole polarizability optimizes the accuracy of the potential with terms through 1/r4. We formulate the single-center expansion in terms of polarization-modified effective multipole moments, defining a form related to the source-multipole expansion of Brink and Satchler. Atom-centered potentials are an origin independent alternative but are limited both by the properties allowed at each center and by the neglected effects like bond polarizability and charge flow. To enable comparisons between single-center effective potentials in Cartesian or spherical form and two-center effective potentials with differing levels of mutual induction between atomic centers, we give analytical expressions for the bond-length and origin-dependence of multipole and polarizability terms projected in the multipole and polarizability expansion of Buckingham. The atom-centered potentials can then be used with experimental data and ab initio calculations to estimate atoms-in-molecules properties. Some results are given for BaF+ and HF showing the utility and limitations of the approach. More detailed results on X ¹∑+ CaF+ are published separately. [ABSTRACT FROM AUTHOR]

The analytical energy gradient and Hessian of the two-component Normalized Elimination of the Small Component (2c-NESC) method with regard to the components of the electric field are derived and used to calculate spin-orbit coupling (SOC) corrected dipole moments and dipole polarizabilities of molecules, which contain elements with high atomic number. Calculated 2c-NESC dipole moments and isotropic polarizabilities agree well with the corresponding four-component-Dirac Hartree-Fock or density functional theory values. SOC corrections for the electrical properties are in general small, but become relevant for the accurate prediction of these properties when the molecules in question contain sixth and/or seventh period elements (e.g., the SO effect for At2 is about 10% of the 2c-NESC polarizability). The 2c-NESC changes in the electric molecular properties are rationalized in terms of spin-orbit splitting and SOC-induced mixing of frontier orbitals with the same j = l + s quantum numbers. [ABSTRACT FROM AUTHOR]

Alkali metal atoms and small alkali clusters are classic heliophobes and when in contact with liquid helium they reside in a dimple on the surface. Here we showthat alkalis can be induced to submerge into liquid helium when a highly polarizable co-solute, C60, is added to a helium nanodroplet. Evidence is presented that shows that all sodium clusters, and probably single Na atoms, enter the helium droplet in the presence of C60. Even clusters of cesium, an extreme heliophobe, dissolve in liquid helium when C60 is added. The sole exception is atomic Cs, which remains at the surface. [ABSTRACT FROM AUTHOR]

A method of calculation of static polarizabilities with wavefunctions, corresponding to linearly approximated explicitly correlated coupled-cluster singles and doubles [CCSD(F12)] model, has been formulated and implemented. For the proper description of the response of system on applied electric field, modified ansatz is introduced for geminal part of cluster operators. Such extension of CCSD(F12) model provides balanced description of both perturbed and unperturbed wave functions, what leads to the increase of the accuracy of target polarizabilities. As a part of algorithm, explicitly correlated version of coupled-perturbed CCSD equations has also been derived and implemented. Numerical tests conducted for the set of eight molecules show good agreement between static polarizabilities, calculated with developed explicitly correlated approach and corresponding complete basis set results in regular CCSD already at triple-ζ level. [ABSTRACT FROM AUTHOR]

We report here the optical, photoluminescence (PL), and dielectric properties of Cd 0.40 Ni 0.60 ZnO 2 nanocomposites annealed between 200 and 600 °C. An increase in annealing temperature (T ann) up to 600 °C correlates with a gradual increase in the crystallite and particle sizes. The surface area, pore radius, and pore volume are increased as T ann increases from 200 °C to 300 °C, and then decreased, but still higher than of 200 °C. Similar behaviors were obtained for the absorbance carrier density, photocatlytic efficiency, degradation rate, PL intensity, dielectric constant, dielectric loss, ac conductivity, F-factor, series resistance, and electronic polarizability. While the energy gap, binding energy, impedance of grains and their boundaries, and effective capacitance show an opposite behavior. The relaxation times at the peak of dielectric parameters are between 11.54 and 159.24 ns and between 35.23 and 24273.73 ns, respectively. The Cole-Cole plot shows a single semicircle at T ann < 400 °C and two successive semicircles at T ann > 500 °C. The energy of PL °f visible emissions is independent on the chosen T ann. These findings indicated that the nanocomposite annealed at 300 °C can be used for water purification, telecommunications, solar cells, supercapacitor, and white light-emitting diodes (LEDs). • The impact of annealing temperature on the properties of Cd 0.40 Ni 0.60 ZnO 2 nanocomposites has been investigated. • Although the D and PZ are gradually increase against T ann , an increase in T ann from 200 to 300 °C correlates with an increase in the surface area, followed by a decrease with an increase in T ann to 600 °C. • Similar behaviors were obtained for the carrier density, dielectric constant, dielectric loss, ac conductivity, F-factor, series resistance, electronic polarizability, and PL intensity. An opposite trend could be obtained for the energy gap, binding energy, and effective capacitance. • The energy of PL of visible emissions indicates that PL is independent of the E g of the annealed composite. • It is approved that nanocomposites annealed at 300 or 400 °C are strongly recommended for water purification, telecommunications, solar cells, supercapacitors, and white light-emitting diodes (LEDs). [ABSTRACT FROM AUTHOR]

In this work, a fluorine and silicon-containing main-chain type benzoxazine (BAF-aptmds) was synthesized from bisphenol AF, 1,3-bis(aminopropyl)tetramethyldisiloxane (APTMDS) and paraformaldehyde. As a control, bisphenol A/APTMDS based benzoxazine (BA-aptmds) was synthesized. The hydrophobicity, thermal properties and dielectric properties of the two polybenzoxazines, PBAF-aptmds and PBA-aptmds, were investigated. The results showed that both polybenzoxazines had high hydrophobicity and low water absorption. Due to the presence of trifluoromethyl groups and siloxane segments, PBAF-aptmds was endowed with excellent low dielectric properties with a dielectric constant of 2.51 and a dielectric loss of 0.0053 at 1 MHz. Meanwhile, PBAF-aptmds exhibited high thermal stability with a glass transition temperature of 286 °C. In addition, the volume polarizabilities and the free volumes of polybenzoxazines were calculated by molecular simulation, which could help to further understand the relationship between their molecular structures and dielectric properties. [Display omitted] • Two silicon-containing main-chain type polybenzoxazines were prepared. • The acquired polybenzoxazines exhibit excellent thermal stability and low dielectric properties. • The introduction of fluorinated groups further decreases the dielectric constant of polybenzoxazine. [ABSTRACT FROM AUTHOR]

There is a great demand for low dielectric materials as insulating interlayers in large-scale integrated circuit development. However, it is still a huge challenge to reduce the dielectric permittivity of polymers while maintaining excellent thermal stability and mechanical properties. In this work, the fluorinated polyimides (PIs) in combination with a micro-branched crosslinking structure were prepared successfully by introducing different amounts of 1,3,5-tris(4-aminophenyl) benzene (TAPB) to obtain ultra-low dielectric permittivity. The results revealed that PI film containing 2 mmol TAPB had the lowest dielectric permittivity (2.47) and dielectric loss (0.008) at 1 MHz due to the fluorine atoms and the micro-branched crosslink structure, which not only decreased the molecular polarizability but also increased the free fractional volume. In addition, PI film containing 2 mmol TAPB had the highest tensile strength of 106.02 MPa with an elongation at a break of 15.1% because the presence of TAPB effectively promoted the connection between PI molecular chains, resulting in the inhibition of the molecular mobility. The incorporation of TAPB also enhanced the thermal stability and ultraviolet light-shielding performance of PI films. This method paves the way for the development of PIs with ultra-low dielectric permittivity for the electronic industry. [ABSTRACT FROM AUTHOR]

The Nb in the structure of ferroelectric KSr2Nb5O15 (KSN) is designated as Nb1 or Nb2 as it is surrounded by differing amounts of oxygen atoms. The dielectric properties and spontaneous polarization intensity of KSN with different Nb5+ vacancies are studied using first‐principles calculations and the influence mechanism of intrinsic cation vacancies on the dielectric properties and spontaneous polarization intensity of KSN is clarified. The dielectric constants and polarization responses to the materials are different when vacancy is formed at these two types of Nb sites, respectively; vacancy at the Nb1 site increases the dielectric constant, whereas vacancy at the Nb2 site decreases it. Furthermore, the experimental results support the effects of Nb5+ vacancy on the polarization behavior of the material, including polarizability and polarization intensity. This study provides a theoretical foundation for better understanding and improving the dielectric properties and polarization behavior of tungsten bronze structure ferroelectrics. [ABSTRACT FROM AUTHOR]

A series of inverse spinel ceramics, Ga 2 [Li 1+ x Ga 3 ]O 8+δ (0.05 = x ≤ 0.125), were synthesized by the conventional solid-phase reaction. The addition of Li (x ≤ 0.1) increased the order degree of octahedra cations and caused an expansion in cell volume, and the maximum solution was located at 0.1–0.125. The dielectric constant of Ga 2 [Li 1+ x Ga 3 ]O 8+δ ceramics increased with the ionic polarizability of primitive unit cell, and the optimum microwave dielectric performances were obtained at x = 0.1 sample sintered at 1260 °C with ε r = 10.78 ± 0.1, Q × f = 171,171 ± 500 GHz, and τ f = −56.47 ± 1.0 ppm/°C. The τ f showed an opposite variation trend to that of the Ga1 bond valence and octahedron distortion. The Q × f was determined by the packing fraction and FWHM of 424 cm−1 Raman mode. In addition, the intrinsic dielectric properties of Ga 2 [Li 1+ x Ga 3 ]O 8+δ ceramics were evaluated by infrared reflectivity spectra. The results show that Ga 2 [Li 1+ x Ga 3 ]O 8+δ ceramic is a promising substrate material. [ABSTRACT FROM AUTHOR]

Structural, dielectric and conductivity of multicomponent borotellurite glasses have been thorougly investigated. Noncrystallinity confirmed through XRD and structural units identified from FTIR spectra. Dielectric constant and loss decreased with increase of frequency and temperature. Polarization parameters such as molar volume, (Vm), molar refraction (Rm), molar polarizability (αm), electronic polarizability (αe) and metallization criterion (M) were determined. Power law behavior of ac conductivity has been verified and frequency exponent obtained. Activation energy of dc and ac conductivity obtained from Mott's small polaron hopping model fits and discussed. Frequency exponent decreased with temperature as predicted by correlated barrier hopping model. Hunt's model fit to conductivity data yielded similar frequency exponent values as obtained from power law. Linear relation between ac and dc conductivity has been observed as predicted by Barton, Nakajima and Namikawa theory. Time-temperature superposition principle has been verified by drawing master curves. [ABSTRACT FROM AUTHOR]