Dielectric Constant Of Composites Research Articles

Co-Ni spinel nanoparticles for energy storage applications: Composition, structural parameters and electrical properties

In the ambit of this investigation, we delved into the properties of (Co/Ni)Fe2O4 spinel nanoparticles (CNSNs) with a spectrum of Co/Ni ratios, delineated as Co1-xNixFe2O4, where x adopts values of 0.0, 0.3, 0.5, 0.7 and 1.0. The synthesis of these CNSNs was adeptly executed via the citrate precursor technique. This study meticulously examined the crystal structure and granular morphology by applying X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was unequivocally determined that each specimen exhibited a homogenous phase. The lattice parameters for the synthesized CNSN compounds agreed with the mean ionic radii of the Co2+ and Ni2+ ions, mirroring their respective concentrations within the nanoparticles. Furthermore, an extensive analysis of the alternating current (AC) electrical properties was carried out, encompassing a broad frequency range from 1 kHz to 3 MHz and a wide temperature range from 303 to 423 K. The observed behavior of the electrical properties was thoroughly evaluated and elucidated, considering the chemical composition of each CNSN. The relationship between the frequency dependency of σac, έ and tanδ is congruent with the prevailing literature and theoretical constructs that elucidate the composite materials' conductivity and dielectric constant, comprising grains and grain boundaries. The present CNSN samples do not exhibit maximum peak for tanδ, potentially due to the wider range of frequencies used than the anticipated peak frequency. The samples' measured conductivity and dielectric constant values displayed a high degree of coherence, corroborating each other's findings. Literature corroborates that the escalation in ac-conductivity values with frequency intimates certainly that the prepared samples may herald promise for utilization in energy storage solutions, bolstering the synergistic efficacy observed. Another conceivable application of these CNSN materials could be their integration in microwave technologies, suggesting a broad scope for future technological advancements.

High dielectric transparent polymer composite with well-organized carboxymethyl cellulose microfibers in silicon elastomer fabricated under direct current electric field

The combination of transparency, high dielectric permittivity, biocompatibility and flexibility is highly desired in the embedded capacitors. Herein, we show that assembling biodegradable sodium carboxymethyl cellulose (CMC) microfibers in biocompatible silicon elastomer (PDMS) under direct current (DC) electric field enables the production of high dielectric constant composite film with above desired properties. This process leads to the formation of columns of CMC microfibers spanning across the thickness direction, thus generating microfiber depleted regions in between fibers and polymer matrix. The as-prepared composite film with CMC (15 wt%) aligned exhibits a remarkable and an almost sevenfold higher dielectric permittivity as compared to that of the film with CMC randomly dispersed (72 vs 11.4, at 100 Hz). This high CMC loading does not compromise the flexibility and optical transmittance. Interestingly, the compression modulus along the thickness direction increases by >20 times from 16.4 MPa (CMC unaligned) to 339.9 MPa (CMC aligned). We demonstrate a facile strategy of fabricating high dielectric materials combining transparency, biocompatibility, flexibility and compression resistant, making the dielectric materials more versatile. This work shows that biomass derived CMC is a promising filler for high dielectric constant polymer composites benefiting from electric field driven construction of ordered micromorphology.

Achieving low dielectric constant and high thermal conductivity polymer composites by using larger POSS functionalized boron nitride nanosheets

A series of larger POSS-functionalized boron nitride nanosheets were prepared and utilized to address the trade-off between low dielectric constants and high thermal conductivity in polymer composites.

Ameliorating and tuning the optical, dielectric, and electrical properties of hybrid conducting polymers/metal oxide nanocomposite for optoelectronic applications

Quaternary nanocomposite films with favorable electrical and optical properties have been produced by adding nickel oxide nanoparticles (NiO NPs) to polyvinyl alcohol (PVA), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), and polypyrrole (PPy) with a solution casting technique. In this study, different concentrations of NiO NPs were added to pure PVA/PEDOT:PSS/PPy blends and investigated through various characterization methods. From transmission electron microscopy (TEM) and X-ray diffraction (XRD) observations, the synthesized NiO NPs have a cubic phase and a diameter that varies between 6 and 40 nm. XRD analysis also indicates that the filling of PVA/PEDOT:PSS/PPy with NiO NPs results in a decrease in the crystallinity of the nanocomposites prepared. Raman analysis demonstrated the existence of prominent distinctive peaks associated with vibrational groups that characterize the synthesized samples, which change randomly with increasing concentrations of NiO NPs. In the UV/VIS spectrum for the PVA/PEDOT:PSS/PPy blend, there were two absorbance peaks at 202 and 224 nm that may result from π→π* and n→π* transitions. The results show that, by increasing NiO NP concentrations, UV/Vis absorbance increased by about 44 % at wavelength ranges from 190 to 240 nm, while optical band gap energies for indirect transitions decreased from 4.96 to 4.85 eV. The AC electrical conductivity of the films has been investigated via impedance spectroscopy at frequencies from 10−1 to 107 Hz. As the NiO NPs concentration in the blend rises, the AC electrical conductivity increases and is shown to follow Jonscher's rule. Additionally, it has been demonstrated that nanoparticle concentration causes a rise in composite dielectric loss and dielectric constant. The reduction in the optical bandgap energies and the enhancement of electrical properties due to the filling with NiO NPs suggest the possibility of using the prepared nanocomposites in optoelectronic devices.

Al@SiO2 Core-Shell Fillers Enhance Dielectric Properties of Silicone Composites.

Over the past decade, there has been significant interest in polysiloxane-based dielectric elastomers as promising soft electroactive materials. Nevertheless, the natural low permittivity of polydimethylsiloxane has limited its practical applications. In this study, we have developed silicone rubber/Al@SiO2 composites with a high dielectric constant, low dielectric loss, and high electrical breakdown strength by controlling the shell layer thickness and the content of the core-shell filler. We also investigated the dielectric behavior of the composites. The use of core-shell fillers has increased the Maxwell-Wagner-Sillars (MWS) relaxation process while reducing the dielectric loss of direct current conductance in silicone rubber composites. Moreover, the temperature dependence of the MWS relaxation time in the composites follows the Arrhenius equation. This strategy of increasing the permittivity of silicone composites through core-shell structural fillers can inspire the preparation of other high dielectric constant composites.

IncorporatedTiO2nanoparticles intoPVC/PMMApolymer blend for enhancing the optical and electrical/dielectric properties: Hybrid nanocomposite films for flexible optoelectronic devices

AbstractIn the present work, sol–gel‐synthesized titanium oxide nanoparticles (TiO2NPs) were added to polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) to create polymer nanocomposites (PNCs) samples. The preparation was carried out via the solution casting method. The synthesized TiO2NPs have a tetragonal anatase phase and an average grain size of 15.7 nm. XRD analysis reveals that the TiO2NPs' addition to PVC/PMMA causes a decrease in the crystallinity of PNCs films. Infrared Fourier analysis demonstrated the interplay/complexity between the PVC/PMMA blend and TiO2NPs. The UV/visible spectrum of the PVC/PMMA blend showed two absorbance peaks at 278 and 208 nm, which may result from the n → π* and π → π* transitions. Also, optical bandgaps for indirect and direct allowed transitions decreased with increasing TiO2NPs concentration. The samples' AC electrical conductivity and dielectric properties were measured at room temperature. As the TiO2NPs content in the nanocomposite rises, a percolating network begins to emerge inside the composite, demonstrating that AC electrical conductivity obeys Jonscher's law. Additionally, it has been demonstrated that nanoparticle concentration leads to a higher composite dielectric loss and dielectric constant. These findings suggest the possibility of using the prepared nanocomposites in capacitive energy storage and optoelectronic devices.HighlightsPVC/PMMA‐TiO2nanocomposites' films were fabricated via the solution casting method.Adding TiO2NPs to PVC/PMMA reduces the crystallinity of the PNCs films.The allowed direct and indirect bandgaps decreased with rising TiO2NPs content.AC conductivity, impedance, and dielectric characteristics were discussed.The findings indicate the use of prepared samples in optoelectronic devices.

Dielectric and conductance of biochar-based PVA flexible nanocomposite film

In various applications, heat energy is derived from electromagnetic energy, especially in microwave appliances. The heat is generated by electromagnetic induction hence understanding the properties of the material used in this application are much required. Also increase in biological awareness shifts the researchers toward the biodegradable material. The objective of this research is to investigate the dielectric and conductance of Polyvinyl alcohol-based nano-bagasse biochar. The network analyzer with a probe is used for the analysis of the dielectric property. The impedance analyzer is used to measure the conductance of the biochar. According to the results of the experiment, Biochar exhibits outstanding conductivity at 10 wt% and 15 wt% concentrations, with 1.46* 10-2 S and 3.87 *10-2 S, respectively. The dielectric loss is decreased at BIA 1200, implying that the nanocomposite at BIA 1200 has superior dielectric performance with less loss. The tangential loss factor and dielectric loss are both low for the BIA1200 combination. These high dielectric loss and constant improved composites could be used in many engineering applications such as defence, aerospace and automobile applications.

Preparation of fluorinated epoxy‐phthalonitrile resins with excellent thermal stability and low dielectric constant

AbstractFluoropolymers find applications in heat‐resistant cables, chemical‐resistant linings, electronic components, cladding materials, and weather‐resistant films. Therefore, it is imperative to improve their temperature resistance level and dielectric properties. In this study, a series of new fluorinated epoxy‐phthalonitrile resins with different mass ratios were prepared by adding phthalonitrile to the epoxy resin matrix, followed by a two‐step reaction of the amine with the epoxy resin at low temperature, and then by the reaction of the nitrile with the epoxy resin and the nitrile group at high temperature. The thermal stability and thermal oxidation stability of the cured products were improved; the initial decomposition temperature for 5% weight loss in air was 375.3°C, indicating good heat resistance performance. In addition, the glass transition temperature and storage modulus of the fluorinated epoxy‐phthalonitrile resins cured products increased with an increase in phthalonitrile content. The storage modulus remained above 1500 MPa until 150°C. The glass transition temperature of fluorinated epoxy‐phthalonitrile resins (at a mass ratio of 5:5) was 180°C, much higher than that of the epoxy resin (which was 140°C). Moreover, the dielectric constant of fluorinated phthalonitrile‐epoxy resin (5:5 mass ratio) was 2.01, which was 39.63% lower than that of fluorinated epoxy resin. The thermoset matrix has potential applications in the fabrication of a variety of low dielectric constant composites for electronic device related industries.

Gas sensing and dielectric properties of TiO2/Stilbite nanocomposites

The present work deals with the detection of ammonia gas by using TiO2/Stilbite composites. It also presents the dielectric properties of Stilbite and it’s composites. The composites are prepared by using Stilbite as a main matrix and TiO2 metal oxide as a filler material with variable wt% via mechanical mixing method. The prepared composites material are characterized by XRD, FTIR technique. The XRD and FTIR pattern of composites ensure the presence of TiO2 in composites. The thick film of TiO2/stilbite composites prepared by using screen printing technique are used to detect ammonia gas. The sensing parameter such as operating temperature, response/recovery time, transient response and gas uptake capacity have been determined. In addition, dielectric properties of composites, in pellets form are studied. The sensitivity of ammonia gas sensing increasing as increase the TiO2 concentration in composites. In addition, dielectric constant of composites are also increases as function of TiO2 concentration.

Improved corona discharge-based modified poling method for 0–3 PZT/PEGDA piezoelectric composites

Among piezo composites, 0–3 type ceramic/polymer-based composites have balanced properties and flexible manufacturing processes, allowing them to tackle challenges in wearable electronics and sensing technology. However, due to a misfit between the dielectric coefficients of the ceramic particles and polymer matrix, poling 0–3 composites is difficult. Therefore, in this study, we develop a novel poling method that combines the merits of normal corona poling and oil-based poling methods to activate a lead zirconium titanate (PZT)/Polyethylene glycol diacrylate (PEGDA) composite. The influence of various parameters (voltage, temperature, poling duration, and time of ageing) on the piezoelectric and dielectric properties of the PZT/polymer composite were evaluated. For the 0–3 PZT/PEGDA composites (67 wt%), the optimal poling parameters were found to be 60 min poling duration, 25 °C, and 24 kV. The d33 (32 pC/N) obtained by the proposed poling method is about 3 times that obtained by the normal corona poling method (11 pC/N). This modified poling method was shown to be more effective than the conventional method for a range of filler contents (50 wt%, 67 wt%, and 75 wt%). It was also found that the d33 value of the PZT/PEGDA composite increased over time and was attributed to the increase of the composite dielectric constant after poling. Finally, sensing elements were assembled from the poled samples and evaluated, which shows the potential for detecting tiny signals in sensing and soft robotics.

Achieving Hydrophobic Ultralow Dielectric Constant Polyimide Composites: Combined Efforts of Fluorination and Porous Fillers

AbstractThe advancement of the microelectronics industry necessitates the use of interlayer insulation materials with low dielectric constants and high mechanical properties. In this paper, a new type of copolymerized fluorinated polyimide (PI) is synthesized, and mixed with polyhedral oligomeric silsesquioxane (POSS) functionalized mesoporous silica (MCM‐41@POSS). The PI/MCM‐41@POSS composites exhibit good hydrophobicity. With the addition of 3 wt% MCM‐41@POSS, the PI composite attained an ultralow dielectric constant (k = 1.88) and low dielectric loss (0.01) at 1 MHz, which is attributed to the mesoporous structure of MCM‐41 and the restriction of polarization in the bonded region. The decorated POSS effectively prevents the penetration of PI molecular chains into the mesopores of MCM‐41. In addition, the PI composites containing 3 wt% of MCM‐41@POSS obtain the highest maximum stress of 104.03 MPa with an elongation at break of 13.73%. The hydrophobic PI composites with ultralow‐k are expected to be good candidates as interlayer materials in microelectronics devices.

Surface Functionalized Barium Titanate Nanoparticles: A Combined Experimental and Computational Study

Barium titanate (BTO) nanoparticles show great potential for use in electrostatic capacitors with high energy density. This includes both polymer composite and sintered capacitors. However, questions about the nanoparticles’ size distribution, amount of agglomeration, and surface ligand effect on performance properties remain. Reducing particle agglomeration is a crucial step to understanding the properties of nanoscale particles, as agglomeration has significant effects on the composite dielectric constant. BTO surface functionalization using phosphonic acids is known reduce BTO nanoparticle agglomeration. We explore solution synthesized 10 nm BTO particles with tert-butylphosphonic acid ligands. Recent methods to quantifying agglomeration using an epoxy matrix before imaging shows that tert-butylphosphonic acid ligands reduce BTO agglomeration by 33%. Thermometric, spectroscopic, and computational methods provide confirmation of ligand binding and provide evidence of multiple ligand binding modes on the BTO particle surface.

Rational design of POSS containing low dielectric resin for SLA printing electronic circuit plate composites

Manufacturing low dielectric constant composites with on-demand macroscopic shape and size is essential for the development of communication-related technologies. Herein, we report a simple method for preparing 3D printed composites with low dielectric constant through the introduction of polymerizable methacryloxypropyl cage polyhedral silsesquioxane (POSS) components into methacrylate-terminated epoxy resin (MEP) matrix, which the dielectric properties of the POSS/MEP composites can be adjusted by varying the loading of POSS. With the addition of 30 wt% POSS, the dielectric constant of composite is as low as 2.68 at 1 MHz, which can be attributed to the intrinsic pores from the POSS components. Additionally, the elongation at break and toughness of this particular composite increase to 1.40% and 15.0 MJ/m3, respectively, while Td5 (the temperatures at which the samples lose 5% their mass) of MEP/POSS composite exceeds 320 °C, indicating its excellent thermal stability. The differential scanning calorimetry (DSC) results show that the on-set thermal-curing temperature of MEP/POSS composites decreases with the increase of POSS loading content, suggesting that reactivity of composite resins can be enhanced through the introduction of POSS. Further, the MEP/POSS composites had a viscosity ranging from 2.05 to 2.40 Pa s, enabling it to be highly suitable for 3D printing resins. Collectively, these excellent properties make MEP/POSS composites to be a promising, alternative resin for fabricating low dielectric constant materials through stereolithography (SLA) based additive manufacturing.

Polyimide composites containing core shell particles with high dielectric constant and low dielectric loss

Flake graphite @polyimide (FG@PI) particles with core @shell like structure were successfully synthesized and subsequently incorporated into PI matrix to prepare pI/FG@PI composite films. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed that flake graphite (FG) was covered by PI coating and showed a fluffy structure. Thermogravimetric analysis (TGA), FT-IR, and XRD were also used to characterize FG@PI particles. The PI intermediate layer increases interaction between particles and films, which is very beneficial for increasing dielectric constant and inhibiting dielectric loss of pI/FG@PI composite. The experimental result shows that the pI/FG@PI composite film with 50wt% filler loading exhibits a high dielectric constant of 83.5 (about 24 times that of pure PI) and low dielectric loss of 0.11 at 1 MHz. Furthermore, its tensile strength is maintained at 78 MPa. This shows that the structure of PI intermediate layer is very beneficial for preparation of high dielectric constant and low dielectric loss composite.

Investigating the dielectric properties of barium titanate nanocomposites using transmission electron microscopy image processing

Barium titanate (BTO) is a ferroelectric perovskite material used in energy storage applications because of its high dielectric constant. A previous study showed that the dielectric constant for BTO nanoparticles drastically increases to over 15,000 at a particle size of 70 nm. This result is highly contested, but its implications to energy storage motivated our investigation into the dielectric constants of BTO nanoparticles that are incorporated into a polymer matrix. We developed a novel method of using image processing techniques on transmission electron microscope images of BTO-polymer nanocomposites. Data on the positions, shapes, sizes, and orientations of BTO nanoparticles were used to build more realistic computational models that simulate the dielectric behavior of the nanocomposites. Here, we investigate the relationship between regions of enhanced electric field and the composite dielectric constant.

Largely improved dielectric properties of polyimide composites by tuning content and formation of CsPbBr3 nanocrystals

High dielectric constant polymer composites have considerable potentials in energy storage and dielectric applications because of simple fabrication process, facile processability, light-weight, excellent thermal stability and mechanical properties. Perovskite (CsPbBr3)/polyimide (PI) composites were successfully prepared via an in-situ polymerization from CsPbBr3 precursor in polyamic acid, followed by thermal imidization. The dielectric properties of polyimide composites were controlled by adjusting the content of CsPbBr3 nanocrystals. The obtained CsPbBr3/PI composites not only possess a high dielectric constant of up to 25.5 but also exhibit low dielectric loss below 0.25. The maximal discharging energy density reached up to 3.10 J cm−3 with 10% CsPbBr3, which is almost 3 times greater than pure PI under the same conditions. In addtiton, outstanding thermal properties of 5% decomposition temperature beyond 530 °C and good mechanical properties. The CsPbBr3/PI composites can be prepared facilely and rapidly on a large scale, which will be a outstanding dielectric material for high temperature polymer film capacitors.

High dielectric constant, flexible and easy-processable calcium copper titanate/thermoplastic polyurethane (CCTO/TPU) composites through simple casting method

In the past few years, there has been a significant demand for the development of high dielectric constant polymer composites for flexible electronic applications. However, the development of these flexible and stretchable dielectrics through simple and economical processing methods still remains challenging. In the present work, we have addressed this problem by developing high dielectric constant, flexible, calcium copper titanate (CCTO)/ thermoplastic polyurethane (TPU) composites through a simple and cost-effective casting method. At room temperature, 40 vol% CCTO/TPU composite exhibited a dielectric constant of 56 (1 kHz) along with an elongation at break of 202%, making it a promising dielectric material for flexible electronics. To our knowledge this is the best among the reported works in ceramic/ polyurethane composites, exhibiting a remarkable combination of high dielectric constant, excellent elongation at break and good mechanical strength. A prototype embedded capacitor was fabricated on copper cladded printed circuit board (PCB) by spin coating and a specific capacitance of 1.05 nF/cm2 was achieved at 1 kHz.

MOF and GNS work synergistically for low-k materials with higher thermal conductivity

In this work, the low dielectric constant composites with higher thermal conductivity are prepared, combining ZIF-8 insulation and graphite nanosheets (GNS) thermal conductivity via designing suitable configuration and synergistically reacting in epoxy resin matrix. It demonstrated that ZIF-8@GNS/EP (ZGNS/EP) composites have decreased by 26.4% in low dielectric constant and increased by 300.7% in thermal conductivity compared with neat EP. The dielectric loss of composites is always less than 0.033(102–107 Hz). Simultaneously, the tensile strength of the 0.5 wt% ZGNS/EP composite is increased by 71.1% than before. Overall, this work presents new ideal to prepare low dielectric constant materials, which also possess low loss and excellent thermal conductivity.

Effect of ZnO–Ag on dielectric properties of ZnO–Ag/P(VDF-TrFE-CTFE) composites

Zinc oxide-silver (ZnO–Ag) particles and ZnO–Ag/poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene)[P(VDF-TrFE-CTFE)] composites were synthesized by a reflux method and a solution route, respectively. The functions of ZnO and Ag particles on the dielectric properties of the composites were investigated. The effect of the molar ratio of ZnO to Ag on the composites was also studied. The results indicated that the optimum molar ratio of ZnO to Ag in the composites with 30 wt.% fillers was 0.6/0.4 for dielectric constant modifier applications. Furthermore, the optimum composite had a dielectric constant of 56 and a dielectric loss of 0.27 at 100 Hz and room temperature. Highlights for paper: The ZnO–Ag/P(VDF-TrFE-CTFE) exhibits excellent dielectric properties. ZnO is mainly used to distribute the Ag particles. Ag is mainly used to improve the dielectric constant of composites.

Finely-reconciled high dielectric constant and low dielectric loss in ternary polymer/Cr2C3/montmorillonite composite films by filler-synergy strategy

Polymer/conductive ceramic composites with high dielectric constant have become research hotspot of dielectric capacitor materials. However, the conductivity and dielectric loss increase when high dielectric constant is achieved. In order to reconcile high dielectric constant and low dielectric loss, in this study, poly (vinylidene fluoride) (PVDF)/chromium carbide (Cr2C3)/montmorillonite (MMT) ternary composite films were prepared by solution cast. Dielectric response based on interfacial polarization was improved and dielectric constant of composites was increased. MMT ceramic was used to suppress interface leakage current. Compared with PVDF/Cr2C3 composites, the conductivity and dielectric loss of ternary composites were reduced.