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PA-KNNT-P(VDF-HFP) composite films were synthesized using facile solution casting technique. Due to their wide range of applications in dielectric and electrical systems, phosphonic acid (PA)-modified tantalum-doped potassium sodium niobate (KNNT)–polyvinylidene fluoride co-hexafluoropropylene P(VDF-HFP) composite films have piqued the interest of academic researchers. Microstructural analysis showed that PA layers incorporated onto the KNNT particles within the polymer matrix. The PA-KNNT-P(VDF-HFP) composite exhibited improved dielectric and electrical performance over a broad range of frequency, and the value of the dielectric constant of the P(VDF-HFP) composites is improved by ≈119 over the P(VDF-HFP) matrix at a filler loading 19 wt.%. Moreover, PA-KNNT-P(VDF-HFP) composite also reveals higher dielectric constant (≈ 119) and AC conductivity than P(VDF-HFP)-KNNT composites, while maintaining suppressed dielectric loss ( ≤ 1.3 at 102 Hz). It is also observed that the PA-KNNT-P(VDF-HFP) composite exhibited an insulator–conductor transition with a percolation threshold of fKNNT = 13.4 wt.%. As a result of their exceptional dielectric and electrical characteristics, PA-KNNT-P(VDF-HFP) composites have the potential to find exciting practical applications in a variety of electronic domains. [ABSTRACT FROM AUTHOR]

An ultra high dielectric constant nanocomposites comprising of poly(vinylidene fluoride) (PVDF) as a polymer matrix and niobium pentoxide (Nb2O5)-reinforced graphene oxide (GO) have been successfully developed using solution casting technique. Scanning electron microscopy (SEM) demonstrates that the homogeneous dispersion of Nb2O5 and GO within the PVDF matrix was realized. The dielectric and electrical properties of the resulting PVDF-GO-Nb2O5 nanocomposite films as a function of frequency were studied. The dielectric constant of the nanocomposites system reached a value of about ≈140 at 100 Hz, with a relatively low dielectric loss factor (≈ 1.4). The enhanced dielectric performance of the PVDF-GO-Nb2O5 nanocomposites was ascribed to the presence of Nb2O5 onto the GO, which exhibits strong interaction between GO and PVDF matrix through hydrogen bonding. Moreover, the experimental results fit well with percolation theory and near the percolation threshold (fc < 2 wt %) with high dielectric constant was achieved for PVDF-GO-Nb2O5 nanocomposites. Furthermore, the AC electrical conductivity was also noticeably enhanced. Our strategy provides a facile method to prepare high dielectric constant and relatively low dielectric loss PVDF-GO-Nb2O5 nanocomposite films that might be suitable for energy storage applications. [ABSTRACT FROM AUTHOR]

Abstract: Surface modification plays an important role to enhance the dielectric constant and minimize the dielectric loss. In this study, poly(methyl methacrylate) (PMMA) composites filled with 2-aminoethanesulfonic acid-modified bismuth ferrite (BiFeO3; BFO) have been prepared via solution casting technique. The surface morphology of the composites provides a better homogeneous dispersion of the particles in the polymer matrix and increases interface compatibility between modified BFO and PMMA matrix. The experimental results show that the composites have high dielectric constant (≈ 147), alternating current (AC) conductivity (1 × 10−5) and relatively low loss (< 1) at 100 Hz. The percolation phenomenon is well observed in the composite having less than 30 wt.% of BFO particles. Further, the composites produce passivation layers on the surface of modified BFO particles which might improve the morphology and promote the space charges, interface effects and dielectric properties. Our strategy is to provide a simple and efficient approach to fabricate high-performance dielectric composites for energy storage applications.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The dielectric properties of poly(vinylpyrrolidone) (PVP)-modified bismuth ferrite (BFO) particles in the poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP) matrix were prepared through solution casting techniques. The composites showed enhanced dielectric constant (90) and reduced dielectric loss (<0.5) at 40 wt% of PVP-modified BFO particles. The dielectric constant of the resultant composites with PVP-modified BFO was much higher as compared to that of unmodified BFO-P(VDF-HFP) composites. The maximum remnant polarization reached (2Pr ∼ 1.12 µC cm−2) in the PVP-modified BFO-P(VDF-HFP) composites. The demonstrated approach might provide a route for using PVP-modified BFO particles to enhance the dielectric and ferroelectric performance of the composites. [ABSTRACT FROM AUTHOR]

Novel three phase composites were prepared by embedding nanographite (GNP) and lead zircon ate titanate (Pb(ZrTi)O3; PZT) into the polyvinyl alcohol (PVA) matrix via solution casting technique. The structural analysis was carried out by using X-ray diffraction technique, which indicated the tetragonal structure of Pb(ZrTi)O3 (PZT). The frequency dependences of dielectric, electrical and ferroelectric properties of the PVA-PZT-GNP composites on different volume fractions of GNP were investigated. The percolation theory was used to progress the dielectric and electrical performance of PVA-PZT-GNP composite. It was observed that the PVA-PZT-GNP composite showed insulator-conductor transition with percolation threshold of 5 vol% of nanographite. The dielectric permittivity of PVA-PZT-GNP composite was achieved as high as ≈117 at 100 Hz at percolation threshold, which was about 17 and 5 times higher than that of pure PVA and PVA-PZT composite, respectively. The ferroelectric hysteresis loop investigation indicated that the three phase composites exhibited much higher electric polarization than that of two phase PVA-PZT composite systems. [ABSTRACT FROM AUTHOR]

ABSTRACT In this work, flexible three phase composite films were prepared with surface functionalized multi-walled carbon nanotubes (f-MWCNTs) and bismuth ferrite (BiFeO3;BFO) particles embedded into the poly(vinylidene fluoride) (PVDF) matrix via solution casting technique. The properties and the microstructure of prepared composites were investigated using an impedance analyzer and field emission scanning electron microscope. The micro-structural study showed that the f-MWCNTs and BFO particles were dispersed homogeneously within the PVDF matrix, nicely seated on the floor of the f-MWCNTs separately. The dielectric measurement result shows that the resultant composites with excellent dielectric constant (≈96) and relatively lower dielectric loss (<0.23 at 100 Hz). Furthermore, the percolation theory is explored to explain the dielectric properties of the resultant composites. It says that the percolation threshold of fMWCNTs = 0.9 wt % and the enhancement of the dielectric constant of the composite was also discussed. In addition, the remnant polarization of the un-poled PVDF-BFO-f-MWCNTs composites (2 Pr ∼1.34 µC/cm2 for 1.1 wt % of f-MWCNTs) is also improved. These three phase composites provide a new insight to fabricate flexible and enhanced dielectric properties as a promising application in modern electrical and electronic devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46002. [ABSTRACT FROM AUTHOR]

ABSTRACT The present research work focused on the dielectric and electrical properties of silver (Ag) doped Pb(Zr,Ti)O3 (PZT) particles embedded in a matrix of poly(vinyl alcohol) (PVA) via solution casting technique. The structural analysis confirmed the presence of Ag particles and the microstructural study revealed that both Ag and PZT particles were successfully homogenized over the polymer matrix. The Ag-PZT-PVA composites showed enhanced dielectric properties over a wide range of frequency and the dielectric constant value of such composites was significantly increased to 366 (100 Hz) at 1.1 wt % filler loading. The percolation threshold of the Ag-PZT-PVA composites was found to be 0.9 wt %. The experimental result well fitted to the percolation theory. The enhancement of dielectric constant of the resulting composite systems might be attributed to the increment of conductivity of the interlayer between PZT and PVA due to the presence of Ag particles, which improved the space charge polarization and Maxwell-Wagner-Sillars (MWS) polarization effects. Furthermore, the remnant polarization of the unpoled Ag-PZT-PVA composites (2 Pr ∼1.48 µC/cm2 for 1.1.wt % of Ag-PZT) has also improved, which is favorable for enhanced ferroelectric properties of the composites. The present findings of the composites might be exploited in the potential application of high performance energy storage devices. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45583. [ABSTRACT FROM AUTHOR]