Polybenzoxazine/organosilicon composites with low dielectric constant and dielectric loss

The evolution of electronic communication technology raises higher requirements for low dielectric constant(low-k)materials.For this,a benzoxazine functional organosilicon(HP-aptes)with dense Si—O—Si crosslinking networks and large sterically hindered tert-butyl groups was prepared by the sol–gel method.Then,a series of polybenzoxazine composites(PPHP)were prepared from intrinsically low dielectric constant bis-functional benzoxazine monomer(P-aptmds)and HP-aptes.The double crosslinking networks of polybenzoxazine and organosilicon further increased the crosslinking density and decreased the dipole density of composites,which endowed the composites with enhanced low-k properties.When the content of HP-aptes is 30%(mass),the crosslinking density was 2.05×10^(-3)mol·cm^(-3),while that of PP-aptmds was 3.31×10^(-3)mol·cm^(-3).In addition,the dielectric constant and dielectric loss of PPHP composite at 1 MHz could reach 2.61 and 0.0056,respectively.

Fabrication of BaTiO3/Epoxy Composites Exhibiting Large Dielectric Constant, Low Dielectric Loss and High Flexural Strength

BaTiO3/epoxy composites consisting of two three-dimensionally interpenetrating networks of BaTiO3 and epoxy phases were prepared using a new approach. The BaTiO3/epoxy composites exhibit a colossal dielectric constant, low dielectric loss and high flexural strength. In the BaTiO3 networks, chemically bonded grain boundaries between neighboring BaTiO3 grains were established, and they are responsible for the colossal dielectric constant and high flexural strength of the BaTiO3/epoxy composites. Furthermore, unlike the conventional ceramic/polymer composites, this approach also makes high loadings of BaTiO3 contents possible for the BaTiO3/epoxy composites without compromising their high flexural strength.

Impact of Native Defects in the High Dielectric Constant Oxide HfSiO_4 on MOS Device Performance

Native dejects in HfSiO4 are investigated by first principles calculations. Transition levels of native detects can be accurately described by employing the nonlocal HSE06 hybrid functional. This methodology overcomes the band gap problem in traditional functionals. By band alignments among the Si, GaAs and HfSiO4. we are able to determine the position of defect levels in Si and GaAs relative to the HfSiO4 band gap. We evaluate the. possibility of these defects acting as fixed charge. Native defects lead to the change of valence and conduction band offsets. Gate leakage current is evaluated by the band offset. In addition, we also investigate diffusions of native defects, and discuss how they affect the MOS device performance.

Dielectric constant predictions for energetic materials using quantum calculations

The dielectric constant(DC)is one of the key properties for detection of threat materials such as Improvised Explosive Devices(IEDs).In the present paper,the density functional theory(DFT)as well as ab-initio approaches are used to explore effective methods to predict dielectric constants of a series of 12 energetic materials(EMs)for which experimental data needed to experimentally determine the dielectric constant(refractive indices)are available.These include military grades energetic materials,nitro and peroxide compounds,and the widely used nitroglycerin.Ab-initio and DFT calculations are conducted.In order to calculate dielectric constant values of materials,potential DFT functional combined with basis sets are considered for testing.Accuracy of the calculations are compared to experimental data listed in the scientific literature,and time required for calculations are both evaluated and discussed.The best functional/basis set combinations among those tested are CAM-B3LYP and AUG-ccpVDZm,which provide great results,with accuracy deviations below 5%when calculated results are compared to experimental data.

Dynamic characteristics of charging effects on the dielectric constant due to E-beam irradiation： a numerical simulation

A series of synthetic variations of material intrinsic properties always come with charging phenomena due to electron beam irradiation. The effects of charging on the dielectric constant will influence the charging dynamic in return. In this paper, we propose a numerical simulation for investigating the dynamic characteristics of charging effects on the dielectric constant due to electron beam irradiation. The scattering process between electrons and atoms is calculated considering elastic and inelastic collisions via the Rutherford model and the fast secondary electron model, respectively. Internal charge drift due to E-field, density gradient caused diffusion, charges trap by material defect, free electron and hole neutralization, and variation in the internal dielectric constant are considered when simulating the transport process. The dynamics of electron and hole distributions and charging states are demonstrated during E-beam irradiation. As a function of material nonlinear susceptibility and primary energy, the dynamics of charging states and dielectric constants are then presented in the charging process. It is found that the variation in the internal dielectric constant is more with respect to the depth and irradiation time. Material with a larger nonlinear susceptibility corresponds a faster charging enhancement. In addition, the effective dielectric constant and the surface potential have a linear relationship in the charging balance. Nevertheless, with shrinking charging affect range, the situation with a higher energy primary electron comes with less dielectric constant variation. The proposed numerical simulation mode of the charging process and the results presented in this study offer a comprehensive insight into the complicated charging phenomena in electron irradiation related fields.

Transmission spectra characteristics of 1D photonic crystals with complex dielectric constant

The characteristics of photonic forbidden bands, transmission gain and absorption of one-dimensional （ID） dual-periodical photonic crystals （PC） with a complex dielectric layer were studied by using the optical transfer matrix （TM） method. The results show that the photonic band gap （PBG） of this structure is enlarged and many transmission resonance peaks appear in PBG. Large transmission gain for transmission peaks is obtained if the imaginary part of dielectric constant is negative. With the increase of the absolute value of the imaginary part, the transmission gain increases firstly and the transmittance gain gets to an apex. The imaginary parts of dielectric constant corresponding to transmission gain apex are different according to wavelength. However, the transmission ratio of resonance peaks is less than 1 if the imagi- nary part of dielectric constant is positive. The properties might be used to design multi-narrow-channel band filters and optical amplification devices synchronously.

Helium Plasma Damage of Low-k Carbon Doped Silica Film:the Effect of Si Dangling Bonds on the Dielectric Constant

The low-k carbon doped silica film has been modified by radio frequency helium plasma at 5 Pa pressure and 80 W power with subsequent XPS, FTIR and optical emission spec- troscopy analysis. XPS data indicate that helium ions have broken Si-C bonds, leading to Si-C scission with C（1s） lost seriously. The Si（2p）, O（ls）, peak obviously shifted to higher binding en- ergies, indicating an increasingly oxidized Si（2p）. FTIR data also show that the silanol formation increased with longer exposure time up to a week. Contrarily, the CHa stretch, Si-C stretching bond and the ratio of the Si-O-Si cage and Si-O-Si network peak sharply decreased upon exposure to helium plasma. The OES result indicates that monovalent helium ions in plasma play a key role in damaging carbon doped silica film. So it can be concluded that the monovalent helium ions besides VUV photons can break the weak Si-C bonds to create Si dangling bonds and free methyl radicals, and the latter easily reacts with O_2 from the atmosphere to generate CO_2 and H_2O. The bonds change is due to the Si dangling bonds combining with H_2O, thereby, increasing the dielectric constant k value.

Plasma-assisted ammonia synthesis in a packed-bed dielectric barrier discharge reactor:roles of dielectric constant and thermal conductivity of packing materials

In this article,plasma-assisted NH;synthesis directly from N;and H;over packing materials with different dielectric constants(BaTiO_(2),TiO_(2) and SiO_(2))and thermal conductivities(Be O,Al N and Al_(2)O_(2))at room temperature and atmospheric pressure is reported.The higher dielectric constant and thermal conductivity of packing material are found to be the key parameters in enhancing the NH;synthesis performance.The NH;concentration of 1344 ppm is achieved in the presence of BaTiO_(2),which is 106%higher than that of SiO_(2),at the specific input energy(SIE)of 5.4 k J·l^(-1).The presence of materials with higher dielectric constant,i.e.BaTiO_(2) and TiO_(2)in this work,would contribute to the increase of electron energy and energy injected to plasma,which is conductive to the generation of chemically active species by electron-impact reactions.Therefore,the employment of packing materials with higher dielectric constant has proved to be beneficial for NH;synthesis.Compared to that of Al_(2)O_(3),the presence of Be O and Al N yields 31.0%and 16.9%improvement in NH;concentration,respectively,at the SIE of5.4 k J·l^(-1).The results of IR imaging show that the addition of Be O decreases the surface temperature of the packed region by 20.5%to 70.3℃ and results in an extension of entropy increment compared to that of Al_(2)O_(3),at the SIE of 5.4 k J·l^(-1).The results indicate that the presence of materials with higher thermal conductivity is beneficial for NH;synthesis,which has been confirmed by the lower surface temperature and higher entropy increment of the packed region.In addition,when SIE is higher than the optimal value,further increasing SIE would lead to the decrease of energy efficiency,which would be related to the exacerbation in reverse reaction of NH;formation reactions.

Liquid Phase Sintering (LPS) and Dielectric Constant of α-Silicon Nitride Ceramic

The spark plasma sintering （SPS） was applied to prepare α-Si3 N4 ceramics of different densities with magnesia, silicon dioxide, alumina as the sintering aids. The mechanism of liquid phase sintering （LPS） wus discussed and the factors influencing the density of the prepared samples were analyzed. The dielectric constant of sintered samples was tested. The experimental results show that the density can be controlled from 2.48 g/ cm^3 to 3.09 g/ cm^3 while the content of the sintering aids and the sintering temperature alter and the dielectric constant is closely dependent on the density of obtained samples.

Nonlinear parametric interactions in ion-implanted semiconductor plasmas having strain-dependent dielectric constants

We report nonlinear parametric interactions using a hydrodynamic model of ion-implanted semiconductor plasmas having strain-dependent dielectric constants（SDDC）. High-dielectric-constant materials are technologically important because of their nonlinear properties. We find that the third-order susceptibility varies in the range 10^-14--10^-12m^2·V^-2 for ion-implanted semiconductor plasmas, which is in good agreement with previous results. It is found that the presence of SDDC in ion-implanted semiconductor plasma modifies the characteristic properties of the material.

Local Dielectric Constant of the Solvent Shell Surrounding Ethyl Acetoacetate in Cosolvent-Modified Supercritical Carbon Dioxide

The enol contents and equilibrium constants for keto-enol tautomerism of ethyl acetoacetate in supercritical (SC) CO2 with and without cosolvent ethanol and in various liquid solvents were investigated by UV spectroscopy. The local dielectric constant about the solute in SC CO2/ethanol system was obtained through the correlation between Gibbs free energy of tautomerism and Onsager-Kirkwood solvent quantity. The great difference between local dielectric constant and that calculated from homogeneous dielectric medium theory suggests clustering of the cosolvent around the solute.

Effective dielectric constant model of electromagnetic backscattering from stratified air–sea surface film–sea water medium

Studies of surface film medium on the sea surface are carried out in this paper for developing the technology to automatically detect and classify sea surface films, and an effective dielectric constant model of electromagnetic backscattering from a stratified air–ocean interface. Numerical results of the new model show the characteristics of effective dielectric constants for the air–sea surface film–sea water medium as follows. The effective dielectric constants decrease with increasing relative dielectric constants of the sea surface films. The effective dielectric constants decrease in horizontal polarization（abbr. HH polarization） and increase in VV vertical polarization（abbr. VV polarization） with increasing radar incident angle. Effective dielectric constants vary with relative sea surface film thickness as a cosinusoidal function of sea surface film thickness. Effective dielectric constant of VV polarization is larger than that of HH polarization. Two potential applications are found with our model, i.e., the retrieval of dielectric constants from the sea surface film, and the film thickness retrieval with our model. Our model has a highly significant influence on improving the technology related to the remote sensing of sea surface films.

Dielectric Constant Calculation of Poly(vinylidene fluoride)Based on Finite Field and Density Functional Theory

In this study,we proposed a novel method that integrates density functional theory(DFT)with the finite field method to accurately estimate the polarizability and dielectric constant of polymers.Our approach effectively accounts for the influence of electronic and geometric conformation changed on the dielectric constant.We validated our method using polyethylene(PE)and polytetrafluoroethylene(PTFE)as benchmark materials,and found that it reliably predicted their dielectric constants.Furthermore,we explored the impact of conformation variations in poly(vinylidene fluoride)(PVDF)on its dielectric constant and polarizability.The resulting dielectric constants ofα-andγ-PVDF(3.0)showed excellent agreement with crystalline PVDF in experiments.Our findings illuminate the relationship between PVDF’s structural properties and its electrical behavior,offering valuable insights for material design and applications.

Research progress on low dielectric constant modification of cellulose insulating paper for power transformers

Because of the increase in the transmission voltage levels,the demand for insulation reliability of power transformers has increasingly become critical.Cellulose insulating paper is the main insulating component of power transformers.To improve the insulation level of ultrahigh voltage transformers and reduce their weight and size,reducing the dielectric constant of oil-immersed cellulose insulating paper is highly desired.Cellulose is used to produce power-transformer insulating papers owing to its excellent electrical properties,renewability,biodegradability and abundance.The dielectric constant of a cellulose insulating paper can be effectively reduced by chemical or physical modification.This study presents an overview of the foreign and domestic research status of the use of modification technology to reduce the dielectric constant of cellulose insulating papers.All the mentioned methods are analyzed in this study.Finally,some recommendations for future modified cellulose insulating paper research and applications are proposed.This paper can provide a reference for further research on low dielectric constant cellulose insulating paper in the future.

Low dielectric constant and highly intrinsic thermal conductivity fluorine-containing epoxy resins with ordered liquid crystal structures

Epoxy resins with a high dielectric constant and low intrinsic thermal conductivity coefficient cannot meet the current application requirements of advanced electronic and electrical equipment.Therefore,novel fluorine-containing liquid crystal epoxy compounds(TFSAEy)with fluorinated groups,biphenyl units,and flexible alkyl chains are first synthesized via amidation and esterification reactions.Then,4,4′-diaminodiphenylmethane(DDM)is used as a curing agent to prepare the corresponding fluorine-containing liquid crystal epoxy resins.The obtained dielectric constant(ε)and dielectric loss(tanδ)values of TFSAEy/DDM at 1 MHz are 2.54 and 0.025,respectively,which are significantly lower than those of conventional epoxy resins(E-51/DDM,3.52 and 0.038).Additionally,the intrinsic thermal conductivity coefficient(λ)of TFSAEy/DDM is 0.36 W/(m⋅K),71.4%higher than that of E-51/DDM(0.21 W/(m⋅K)).Meanwhile,the corresponding elastic modulus,hardness,glass transition temperature,and heat resistance index of TFSAEy/DDM are 5.73 GPa,0.35 GPa,213.5◦C,and 188.7℃,respectively,all superior to those of E-51/DDM(3.68 GPa,0.27 GPa,107.2℃,and 174.8℃),presenting potential application in high-heating electronic component packaging and printed circuit boards.

Study of Structural, Optical, Electrical and Dielectric Properties of Gd-Doped ZnO Composites Synthesized by Solid State Reaction Method

In this manuscript, we are reporting structural, bonding, optical, dielectric, and electrical properties of Gd-doped ZnO composite samples (Zn1−xGdxO, x = 0, 0.05, 0.10) prepared by solid-state reaction method. XRD spectra confirm the wurtzite hexagonal phase with a grain size distribution of 42 - 47 nm. The FT-IR spectra confirm bonding behavior like Zn-O, O=C=O, and O-H stretching modes. FESEM micrographs show that the grains of crystallites possess nearly spherical morphology. Optical absorption spectra confirm that the optical band gap decreases systematically from 3.19 eV to 3.15 eV for x = 0.0 to x = 0.10 samples. For all samples, PL spectra exhibited near-band emission, blue emission, and green emission peaks. The dielectric constant decreases as the applied frequency increases. Hall effect results show that with increasing doping concentration of Gd, mobility and resistivity increase while bulk concentration decreases. Current-Voltage study shows that current increases when temperature is increased. Rare earth-doped ZnO is potential material used for optoelectronics and spintronics device applications. Properties of Gd-doped ZnO are studied by various research groups, but dielectric studies are limitedly reported. Therefore, the present research work aims to study the change of electrical, optical, and dielectric properties of Gd-doped ZnO for device applications.

Dielectric composites with a high and temperature-independent dielectric constant

Dielectric composites made using P(VDF-CTFE)88/12 mol%as polymer matrix and both micro-sized and nano-sized CaCu3Ti4O12(CCTO)particles as filler are developed.These composites exhibit high dielectric constant with a small dielectric loss.More importantly,it is found that the dielectric constant of these composites is almost independent of temperature from 25℃to 125℃.Comparing the composites made using micro-sized CCTO particles,the composites made using nano-sized CCTO particles exhibit a smaller dielectric loss.The dielectric properties of these composites indicate that the nano-sized CCTO particles have a smaller dielectric constant than the micro-sized CCTO particles.

Highly Transparent and Colorless Polyimide Film with Low Dielectric Constant by Introducing Meta-substituted Structure and Trifluoromethyl Groups

An effective design strategy for preparing highly transparent polyimide film with low dielectric constant is presented.The key to the strategy is to simultaneously introduce meta-substituted structure and trifluoromethyl in polymer chains.By using this design strategy,a highly transparent polyimide film with low-k was synthesized from 3,5-diaminobenzotrifluoride(m-TFPDA)and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride(6FDA)through a two-step method.The obtained m-TFPDA/6FDA(CPI)film(~30 pm)possesses high optical transparency(λ_(cutoff)=334 nm,T_(450nm)=85.26%,Haze=0.31)and is close to colorless(L^(*)=96.03,a^(*)=-0.34,b^(*)=2.12,yellow index=3.96).The intrinsic k and dielectric loss value of the film are 2.27 and 0.0013 at 10 kHz,respectively.More importantly,such low dielectric performance could remain stable up to 280℃,and the film shows a low moisture rate(~0.51%),which helps to maintain the low-k property stability in different humid environments.Meanwhile,the film also shows good thermal stability and mechanical properties,with a glass transition temperature(T_(g))of 296℃and the 5 wt%decomposition temperature(T_(d,s%))of 522℃under N_(2).The tensile strength and tensile modulus of the film are 85.1 MPa and 1.96 GPa,respectively.In addition,the film is soluble in common solvents,which allows simple solution processing and low-cost,continuous roll-to-roll processes.This design strategy is beneficial to improving the transparency,lightening yellow color,lowering the dielectric constant and meanwhile maintaining the comprehensive properties of polyimide films,which is mainly due to the introduced meta-substituted and trifluoromethyl structures effectively inhibiting the transfer of charge transfer complex(CTC)effects and increasing the free volume of film.This design strategy could also be extended to other high-performance polymer systems.

Ternary polymer nanocomposites with concurrently enhanced dielectric constant and breakdown strength for high-temperature electrostatic capacitors

The exploration of high-energy-density electrostatic capacitors capable of operating both efficiently and reliably at elevated temperatures is of great significance in order to meet advanced power electronic applications.The energy density of a capacitor is strongly dependent on dielectric constant and breakdown strength of a dielectric material.Here,we demonstrate a class of solution-processable polymer nanocomposites exhibiting a concurrent improvement in dielectric constant and breakdown strength,which typically show a negative correlation in conventional dielectric materials,along with a reduction in dielectric loss.The excellent performance is enabled by the elegant combination of nanostructured barium titanate and boron nitride fillers with complementary functionalities.The ternary polymer nanocomposite with the optimized filler compositions delivers a discharged energy density of 2.92 J cm^−3 and a Weibull breakdown strength of 547 MV m^−1 at 150℃,which are 83%and 25%,respectively,greater than those of the pristine polymer.The conduction behaviors including interfacial barrier and carrier transport process have been investigated to rationalize the energy storage performance of ternary polymer nanocomposite.This contribution provides a new design paradigm for scalable high-temperature polymer film capacitors.

DEVELOPMENT OF POLYMER-BASED 0-3 COMPOSITES WITH HIGH DIELECTRIC CONSTANT

Composites have been extensively studied for dielectric and related applications.This is a reviewof polymer based 0-3 composites that exhibit a high dielectric constant.These composites areclassified into two types.Dielectric-dielectric composite and conductor-dielectric composite.The physical principles and related models are presented with associated assumptions and ap-proximations.In general,a dielectric-dielectric composite needs a higher concentration of thefillers to reach a high dielectric constant than a conductor-dielectric composite.The high dielectric constant observed in the conductor-dielectric composites is usually associated with ahigh dielectric loss and a low electric breakdown field.The experimental results are summarized toillustrate the principles for,and the achievements in,the development of these composites.The challenges facing the fundamental understanding and the further development of these compo-sites for diferent applications are discussed.