Dielectric Properties Of Nanocomposites Research Articles

Improvement in Dielectric Properties of Polyacrylate Copolymers by Engineering the Interphase Region with Polymer-Grafted Reduced Graphene Oxide

In this study, an innovative interfacial design strategy aimed to investigate the effects of interfacial interactions between the matrix and reduced graphene oxide (rGO) on the dielectric properties of nanocomposites. The polymer matrices with varying comonomer ratios of butyl acrylate and methyl methacrylate were synthesized to deliberately engineer diverse interfacial interactions with polymer-grafted reduced graphene oxide. Through this approach, fine-tuned interfacial interactions between the polymer matrix and polymer-grafted rGO were achieved, which was verified by FE-SEM, DSC, and DMTA analysis. Subsequently, the dielectric properties of the nanocomposites were investigated to elucidate the relationship between interfacial strength and dielectric efficiency. It was found that polymer nanocomposites with enhanced interfacial interactions exhibit higher dielectric permittivity compared to the neat matrix. This enhancement was attributed to the increased charge storage in the interfacial area and improved alignment of polarizable polymer chains in the interphase between the polymer matrix and polymer-grafted rGO.

High thermal conductivity and low dielectric polyimide nanocomposites using diamine-assisted mechanochemical exfoliation boron nitride and in-situ polymerization under pressure

Advanced integrated circuit materials demand polymer composites with exceptional thermal conductivity and low dielectric constant to minimize power consumption and improve signal transmission. However, conventional methods of improving the thermal conductivity of composites by incorporating thermal conductive fillers result in an increase in dielectric constant, producing a huge challenge in simultaneously achieving enhanced thermal conductivity and low dielectric constant. Herein, a brick-and-mortar structure has been successfully constructed through in-situ polymerization of the diamine-assisted mechanochemical exfoliated (DAME) boron nitride (BN) with trifluoromethyl-containing PI and microporous polyhedral oligomeric silsesquioxane (POSS) under pressure. The DAME functionalized BNNS (f-BN) exhibit high aspect ratios, few lattice defects, high yields and excellent dispersion in the POSS/PI matrix. Notably, the obtained 40 wt% f-BN/POSS/PI nanocomposite exhibits a high in-plane thermal conductivity of 17.76 W m−1 K−1 with a 488% enhancement compared to 40 wt% hBN/POSS/PI, and simultaneously maintains low dielectric constant of 2.76 and low dielectric loss of 0.0042 at 1 MHz close to the pure POSS/PI matrix. Density functional theory is utilized to reveal the possible chemical reactions between f-BN and diamine, and the impacts of interfacial functionalization on the thermal conductivity and dielectric properties of nanocomposites are illustrated by molecular dynamics simulations. Furthermore, the DAME method demonstrates good universality among polyimide matrices, and shows excellent practical implementation as a thermal interface material and flexible printed circuit board. This material provides a promising solution for integrated circuits by successfully addressing the challenge of combining low dielectric constant and high thermal conductivity in microelectronic systems.

Novel relaxor ferroelectric BTWO nanofillers for improving the energy storage performance of polymer-based dielectric composites

The fast growth of electronic gadgets and power systems has increased the demand for high energy-storage polymer-based film capacitors, However, because of the relatively low dielectric constant (εr), the discharged energy density (Ud) is severely limited, so increasing the εr of nanocomposites is an effective way to increase Ud. In this paper, Bi6Ti5WO22 (BTWO), a novel non-perovskite relaxation ferroelectric ceramic, is selected as nanofillers due to its ultra-low loss and high tunable dielectric constant, and BTWO/P(VDF-HFP) nanocomposites are prepared by compounding with ferroelectric polymers. BTWO nanoparticles' high εr (∼2200) and low loss (∼0.001) increase not only the breakdown strength (Eb) and dielectric properties of nanocomposites, but also their insulating and mechanical characteristics. It is worth noting that when the 5 vol% BTWO nanofillers are loaded, the εr of the nanocomposite is 11.3 and the highest Eb is up to 575 MV·m−1, and the optimal Ud and efficiency (η), with 22.6 J·cm−3 and 71.3 %, are attained at the same moment. In this work, a new relaxation ferroelectric ceramic BTWO is selected as the filler, which provides a new strategic route for the preparation of energy storage polymer-based dielectric.

Dielectric Properties of a Nanocomposite from RbNO3 Incorporated into Pores of Al2O3 Matrix

The present work reports the experimental results of studying linear and nonlinear dielectric properties of a ferroelectric nanocomposite from RbNO3 embedded in pores of an Al2O3 matrix. The dielectric relaxation times were determined above and below the phase transition temperature of pure RbNO3 (436 K). It was shown that for RbNO3 incorporated into nanosized pores of the Al2O3 matrix, a decrease in the phase transition temperature and a change in relaxation times were observed.

Enhanced Interfacial and Dielectric Performance for Polyetherimide Nanocomposites through Tailoring Shell Polarities

Polyimide (PI) and its derivative polyetherimide (PEI) have been widely investigated as promising candidates for dielectric energy storage due to their excellent intrinsic features. However, most of the current research for PI- or PEI-based dielectric nanocomposites only focuses on a certain polar group contained in a dianhydride monomer, while there are very few studies on exploring the effect of a series of polar groups derived from various dianhydride monomers on the dielectric properties of nanocomposites. To fill this gap, we herein fabricated and investigated a series of novel hyperbranched polyimides grafted on barium titanate nanoparticles (HBPI@BT) using different dianhydride monomers and their nanocomposites with the PEI matrix. The results showed that sophisticated hyperbranched structures effectively alleviated the incompatibility between fillers and the matrix, thus significantly improving the bonding energy of nanocomposites, especially for HBPI-S@BT/PEI (797.7 kJ/mol). The Ud of HBPI-S@BT/PEI reached 8.38 J/cm3, which is 3.3 times higher than that of pure PEI. The HBPI-F@BT/PEI nanocomposites achieved high breakdown strength (∼500 MV/m) and low dielectric loss (0.008) simultaneously. The dielectric constants of HBPI@BT/PEI nanocomposites remained at a stable level from 25 to 150 °C. This work provides us promising hyperbranched structured materials for potentially advanced dielectric applications such as field effect transistors.

Spark plasma sintered Si(Hf)OC nanocomposites exhibiting thermally stable dielectric behavior processed through precursor route

This work uses hafnium n tetra butoxide precursor to modify silicon oxycarbide (SiOC) with an easy, novel, and economical procedure to synthesize Si(Hf)OC nanocomposites. FTIR analysis confirmed the formation of Si–O-Hf linkages during cross-linking. The as-pyrolyzed powders were sintered using the spark plasma sintering technique. X-ray diffractograms confirmed the in-situ crystallization of tetragonal HfO2 in an amorphous SiOC matrix. The morphological features were imaged using electron microscopy. The dielectric properties of sintered Si(Hf)OC nanocomposites were investigated at varied temperatures (25 °C–250 °C) and frequency ranges (10−1 Hz–106 Hz) for the first time. At room temperature, the ε՚ value at 1 kHz is found to be 14, which is almost double the value of pure sintered SiOC (ε՚∼5). The dielectric loss (tanδ) is less than 0.07 at 1 kHz at room temperature, which is significantly less than sintered SiOC (tanδ ∼0.5). An increase in permittivity is associated with high permittivity t-HfO2 nanocrystals and additional interfacial/space charge polarization at the interfaces between the t-HfO2 and SiOC matrix. At high-frequency regions (>1 kHz), the dielectric properties of nanocomposites were found to be thermally stable (up to 250 °C). At low-frequency regions (<70 Hz), the material exhibits a rise in dielectric permittivity with increasing temperature, most likely due to charge carrier accumulation at the interfaces of t-HfO2, SiO2, and carbon in the SiOC matrix through the migration of thermally activated charge carriers.

Design and characterization of molecular, crystal and interfacial structures of PVDF-based dielectric nanocomposites for electric energy storage.

PVDF-based polymers with polar covalent bonds are next-generation dielectric materials for electric energy storage applications. Several types of PVDF-based polymers, such as homopolymers, copolymers, terpolymers and tetrapolymers, were synthesized by radical addition reactions, controlled radical polymerizations, chemical modifications or reduction with the monomers of vinylidene fluoride (VDF), tetrafluoroethylene (TFE), trifluoroethylene (TrFE), hexafluoropropylene (HFP) and chlorotrifluoroethylene (CTFE). Owing to rich molecular structures and complicated crystal structures, PVDF-based dielectric polymers can show versatile dielectric polarization properties, including normal ferroelectrics, relaxor ferroelectrics, anti-ferroelectrics and linear dielectrics, which are beneficial for designing polymer films with high capacity and high charge-discharge efficiency for capacitor applications. Furthermore, to satisfy the requirements of practical high-capacity capacitors, the polymer nanocomposite method is another promising strategy to achieve high-capacitance dielectric materials by the addition of high-dielectric ceramic nanoparticles, moderate-dielectric nanoparticles (MgO, and Al2O3), high-insulation nanosheets (BN), etc. It is concluded with the current problems and future perspectives of interfacial engineering, such as core-shell strategies and hierarchical interfaces in polymer-based composite dielectrics for high-energy-density capacitor applications. In addition, an in-depth understanding of the roles of interfaces on the dielectric properties of nanocomposites can be achieved by indirect analysis techniques (theoretical simulation) and direct analysis techniques (scanning probe microscopy). Our systematic discussions on molecular, crystal and interfacial structures provide guidance for designing fluoropolymer-based nanocomposites for high-performance capacitor applications.

Scalable, flexible, and hierarchical porous conductive nanocomposites for self-powered and pressure sensing dual-mode integration

Multimodal sensing is promising in applications of fast responses to multi-source stimulus under complex tasks like intelligent robot perception and human motion monitoring. In this work, a flexible piezoresistive carbon nanotubes (CNTs) nanocomposites-based triboelectric nanogenerator (PC-TENG) dual-modal sensor is presented. Such hierarchical porous structures based on CNTs/polydimethylsiloxane (PDMS) nanocomposites were prepared by a facile scalable template sacrifice method. The dual-modal PC-TENG sensor can achieve decoupling responses of self-powered and self-sensing by optimizing conductive and dielectric properties of nanocomposites, via integrating elastic porous PDMS structures embedded with percolating conductive CNTs networks. The PC-TENG sensor exhibits high performances of triboelectric output with an open-circuit voltage of 120 V, a short-circuit current of 8 μA, and an output power of up to 139.5 μW, as well as low hysteresis and highly sensitive piezoresistive effect. The excellent electromechanical property of PC-TENG sensor enables it to be used as a self-powered and piezoresistive dual-mode flexible sensor. We further demonstrated that PC-TENG sensor has a dualmodal sensing precision and rapid response capability that facilitates detections of wearable devices operation, health monitoring devices in complex environments without being interfered by a single signal.

Effect of carbon nanotube location and dispersed phase on the dielectric properties of polypropylene/high‐density polyethylene/carbon nanotube nanodielectrics

AbstractThe effect of carbon nanotube location and dispersed phase on the dielectric properties of nanocomposites with carbon nanotubes (CNTs) and polypropylene/high‐density polyethylene (PP/HDPE) blends was investigated. Different compatibilizers styrene‐ethylene‐buthylene‐styrene copolymer (SEBS), ethylene‐propylene‐diene‐methylene rubber (EPDM), and ethylene‐propylene copolymer (EP) were used. In order to obtain a smaller HDPE phase, 0.1%(w/w) of CNT was added to a PP/HDPE (90/10) blend with 3%(w/w) of compatibilizer. Samples were processed in a twin‐screw extruder with a controlled sequential mixing based on thermodynamic (using the wetting parameter, ) and kinetic parameters (such as melting temperature and melting flow indices). FESEM images show the formation of nanoblends for all compositions, with a dispersed morphology with HDPE droplets with a diameter of about 100 nm (measured with ImageJ© software) inside the PP matrix, and TEM images show the CNTs present in both phases. However, compatibilizers seemed to expel the nanoparticles from the dispersed phase, which may have contributed to a reduction of the dielectric constant of the CNT nanocomposites. Dielectric properties were evaluated through Impedance Spectroscopy, showing that CNTs contribute to the interfacial polarization and constant dielectric rise from 3.15@1 Hz (without CNTs) to 16.91@1 Hz (with CNTs, but no compatibilizer).

Core-shell Structured Ag@PDA Nanowires and BT@PDA Nanoparticles for Three-phase Flexible Polymer Nanocomposites with Excellent Dielectric Properties

In this work, core-shell structured polydopamine coated silver nanowires (Ag@PDA NWs) and polydopamine coated BaTiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> nanoparticles (BT@PDA NPs) are accurately prepared. Through embedding Ag@PDA NWs and BT@PDA NPs into the P(VDF-HFP) matrix, flexible nanocomposites with high dielectric constant and low dielectric loss are prepared by constructing three-phase structure. The crystal structure, thermal properties and dielectric properties of the nanocomposites are fully investigated. Compared with two-phase nanocomposites, which are composed by Ag@PDA NWs and P(VDF-HFP), the dielectric constant of the three-phase nanocomposites is improved from 28.1 to 67.9. Additionally, owing to the presence of the polydopamine shell, the nanofillers are homogeneously dispersed and the interfacial adhesion between the nanofillers and polymer matrix is also enhanced, leading to the dielectric loss and electric conductivity of three-phase nanocomposites remain relatively low level. Furthermore, the dielectric properties of the three-phase nanocomposites exhibit weak temperature dependence.

Investigation of Structural and Dielectric Properties of (Polymer Blend/Oxides Nanoparticles) for Pressure Sensors

This paper aims to fabricate (polyethylene oxide-polyvinyl pyrrolidone) blend and (poly (ethylene oxide-polyvinyl pyrrolidone-cerium dioxide nanoparticles-manganese dioxide nanoparticles) nanocomposites have been investigated for a pressure sensor. The nanocomposites(NCs) are prepared for different concentrations of polymer blend, cerium dioxide nanoparticles, and manganese dioxide nanoparticles. The electrical properties (dielectricconstant, dielectricloss and A.C electrical conductivity) of (PEO-PVP-CeO2-MnO2)nanocomposites have been studied. The dielectric properties of nanocomposites are examined in the frequency range (100 Hz–5×106 Hz). The experimental results displayed that dielectricconstant, and dielectricloss rise with an increase of the weight percentages of manganese dioxidenanoparticles. The dielectricconstant and dielectriclosses reduce as the frequency increases. The AC electrical conductivity has a high value as the weight percentages of manganese dioxidenanoparticles and the frequency increases. The nanocomposites were examined for the pressure sensors application in the pressure range (80–160) bar. The results showed that the electric capacitance of NCs samples is increased as the pressure increases. Also, the electric capacitance of nanocomposites increases with an increase in the weight percentages of manganese dioxide nanoparticles. Finally, the results showed that the (PEO-PVP-CeO2-MnO2) nanocomposites have a high sensitivity to the pressure.

Optical and dielectric properties of nanocomposites on base nanoporous glasses with silver and silver iodide nanowires

It is experimentally shown that the electrolysis of silver salt in silicate nanoporous glasses (NPGs) with interconnecting pores, having average sizes of 25 nm, makes possible to fabricate metal-glass nanocomposites. Silver component of nanocomposites consists of fractal microbranches, which, in turn, consist of silver nanowires. By iodizing silver nanowires can be transformed to AgI nanowires. Absorption and luminescence spectra of fabricated nanocomposites are presented. Dielectric spectra of “Ag nanowires-glass” nanocomposite were measured in temperature range of −50 … +250 OC for frequencies of 0.1–106 Hz. Dielectric measurements of “AgI nanowires -glass” nanocomposite have shown the presence of phase transition, typical for crystalline AgI.

Mechanical, thermal, and dielectric properties of polyvinylidene fluoride nanocomposites fabricated by introducing functional MWCNTs/barium titanate compounding dielectric nanofillers

AbstractA facile strategy through incorporating barium titanate (BT)/multiwalled carbon nanotubes (MWCNTs) compounding dielectric nanofillers into polyvinylidene fluoride (PVDF) via melt‐processing was proposed. Benefiting from the strong interfacial interactions between BT and MWCNTs, as well as oxygen‐containing groups of BT/MWCNTs and fluorine atoms of PVDF, the sandwiched structure was constructed and thus tailoring the microstructure and enhancing the mechanical, thermal and dielectric properties of resultant nanocomposites. The effects of BT/MWCNTs multiscale dielectric nanofiller on the mechanical properties, heat resistance and dielectric properties of nanocomposites were investigated by infrared spectra, X‐ray diffraction (XRD), differential scanning calorimetry (DSC) analysis, field emission scanning electron microscope, tensile and dielectric tests. XRD and DSC analysis indicated that compared with neat PVDF, BT/PVDF and MWCNTs/PVDF nanocomposites, the BT/MWCNTs/PVDF nanocomposites showed higher crystallinity and thermal properties. The dielectric performance tests showed that the BT/MWCNTs/PVDF nanocomposites had better dielectric performance than those of BT/PVDF and MWCNTs/PVDF nanocomposites. At 100 Hz, the dielectric constant of BT/MWCNTs/PVDF nanocomposites reached 119, which was 14 times that of neat PVDF, and the dielectric loss was only 0.051. The BT/MWCNTs/PVDF nanocomposites showed the tensile strength of 57.7 MPa and the tensile modulus of 1226 MPa, respectively. This work provides a novel strategy for the fabrication of PVDF based dielectric nanocomposites, inspiring the research and development of PVDF in the energy‐related areas in the future.

The influence of titanium dioxide (TiO2) nanoparticles on the structure, optical and dielectric properties of polyvinyl chloride (PVC)

The tendency to improve the properties of insulating materials by incorporating inorganic nanoparticles has become necessary in order to design new insulation systems. In this study, PVC/TiO2-based nanocomposites with different loadings (3, 5 and 10 wt.%) of TiO2 nanoparticles were prepared by the solution mixing method. The morphology of the prepared nanocomposites was studied by Atomic Force Microscope (AFM). Experimentally, it was found that as the concentration increases, the size of the surface structural elements and particle size increases. Photoluminescence (PL) analysis of samples shows improvement compared to the pristine polymer. Furthermore, PL intensity for nanocomposites increases depending on the concentration and saturation occurs at a certain amount of titanium dioxide nanoparticles. The increase in luminescence intensity till a certain nanoparticle content is due to the growth of the luminescent surface area. Further saturation is explained by the increase in particle size with no increase or a slight reduction in surface area. Dielectric properties of nanocomposites were studied. It was found that dielectric permittivity of the materials increases as the nanoparticle volume content increases and it reaches at its highest value for the nanocomposites with 3% nanoparticle content. The optical properties of the polymer and nanocomposite films were studied in the region 200 nm to 600 nm. It was found that the PVC/TiO2 nanocomposites showed enhancement in the absorbance intensities which was more significant for the nanocomposites with higher nanoparticle content compared to the pristine polymer. Furthermore, absorption spectra were used to calculate the optical bandgap of the prepared nanocomposite films and redshift observed in the calculated values of bandgap for nanocomposites. Consequently, it was proved that by incorporating TiO2 nanoparticles into the polymer matrix, the spectral region of the samples can be expanded resulting in broadened application of such systems in various fields of science and technology.

The Effect of Carbon Coatings on the Electrochemical Performance of Composite Electrodes

This work focuses on the effects of sample preparation and particle size on the dielectric properties of polymer nanocomposites. A comparison between the dielectric permittivity and dielectric loss of Polymethyl methacrylate (PMMA) samples, prepared by solution casting and compression molding, has been achieved. A Time Domain Spectrometer and an Agilant (HP) 4284A LCR precision meter, were furbished and used to measure the dielectric properties of insulating nanocomposite materials. The cast samples have shown different dielectric responses from the melt-pressed samples. These differences diminish with lengthening the dry time of the cast samples under vacuum. In addition, nanocomposite and microcomposite samples were prepared by solution casting of PMMA solution and Titanium dioxide (TiO2) particles. The dielectric properties of the nanocomposites were different from the polymer samples where a decrease in the dielectric permittivity of the nanocomposite has been observed. These differences in the dielectric response of the PMMA sample and the nano/micro composite samples might be due to many issues such as, sample preparation or the aggregation of the TiO2 nanoparticles in the polymer matrix. Furthermore, polymer-blends samples of PEO and PMMA have been prepared by solution casting method. The results reported in this work show similar trend compared to those reported in the literature.

The optic and dielectric properties of CuO deposited barite pigments

The CuO deposited barite pigments (CBP) were obtained by direct deposition method. Optic and dielectric properties of nanocomposites were investigated. Hence, the prepared pigments were structural scanning electron microscope (SEM). The optic properties of pigments were evaluated with ultraviolet&amp;amp;ndash;visible spectrophotometer (UV-Vis). The scanning electronic microscopy results show that barite was coated with CuO uniformly. The UV-Vis results show that CuO deposited barite pigments (CBP) have high ultraviolet shielding performance. Furthermore CuO deposited barite pigments (CBP) exhibited UV-Vis reflectance than those of pure-CuO. Furthermore, the conductivity of barite flakes increased with the coating of CuO nanoparticles. The dielectric properties of CuO deposited barite pigments were determined in the frequency range of 8.2&amp;amp;ndash;12.4 GHz via vector network analyzer and the electromagnetic absorption properties of nanocomposite was determined and calculated by using these dielectric values (permittivity). CuO deposited barite/epoxy nanocomposite (mass ratio is 3:10) with 2 mm thickness showed a minimum reflection loss of -9 dB at 12.25 GHz frequency. Furthermore, the conductivity of barite flakes increased with the coating of CuO nanoparticles.

Structural, Dielectric and Optical properties for (Polyvinyl Alcohol–Polyethylene Oxide- Manganese Oxide) Nanocomposites

Due to the scientific, industrial, electrical and medical importance, it was necessary to study the properties of overlapping nanocomposites. So it gained the attention and directed scientists and researchers in the study of its structure and electrical characteristics and other characteristics. So, In the present work, (polyvinyl alcohol- polyethylene oxide- manganese oxide nanoparticles) nanocomposites have been prepared with different concentration of blend and MnO2 nanoparticles. The manganese oxide nanoparticles were added to (PVA-PEO) blend by weight percentages are (2, 4 and 6) wt.%. .The optical microscope images indicate that the manganese oxide nanoparticles additive distribution was homogeneous in the (PVA-PEO) blend. FT-IR indicate that no change on chemical structures between the (PVA-PEO) blend and manganese oxide nanoparticles additives. The dielectric properties of nanocomposites were studied.The results showed that the dielectric constant, dielectric loss and electrical conductivity of (PVA-PEO) blend are increased with the increase in concentrations of manganese oxide nanoparticles. The dielectric constant and dielectric loss decrease while the AC electrical conductivity increases with the increase in frequency of applied electric field. Optical measurements are showed the absorbance of(PVA-PEO-MnO2) nanocomposites is increased with increase of the concentrations of MnO2NPs.With increasing of the concentrations of manganese oxide nanoparticles, the indirect energy gap (Eg) of (PVA-PEO) blend will be decreased. And by increasing of the weight percentages of manganese oxide nanoparticles,the optical constants as absorption coefficient, extinction coefficient, refractive index, real and imaginary dielectric constants of nanocomposites are varied.

Optical and Dielectric Properties of Nanocomposites Based on Zinc and Tin Oxides in Nanoporous Glass

The spectra of the optical density and luminescence and dielectric spectra of crystalline nanoparticles (NPs), as well as micro- and nanodendrites of zinc and tin oxides in silicate nanoporous glass (NPG) with the average pore size of 25 nm, are presented. Oxide nanoparticles were synthesized in the bulk of nanoporous glass by the method of thermodissociation of zinc and tin salts. Oxide nanodendrites were synthesized by the oxidation of zinc and tin nanodendrites which were grown in glass pores via the method of electrolysis. It is demonstrated that the luminescence of nanoparticles and nanodendrites of Zn and Sn is caused by defects in the crystal structure. The optical and dielectric properties of the nanocomposites with nanoparticles and nanodendrites are compared. The obtained results can be used to create chemical and biological sensors, as well as in photocatalysis.

Enhanced dielectric properties of PVDF nanocomposites with modified sandwich-like GO@PVP hybrids

ABSTRACTHerein, graphene oxide (GO) nanosheets coated with insulated polyvinyl pyrrolidone (PVP) were integrated into poly(vinylidene fluoride) (PVDF) to investigate the effects of the insulating PVP shell, loading, and its reaction time on the dielectric properties of the nanocomposites. Compared with the pristine GO/PVDF, the GO@PVP/PVDF nanocomposites show an improvement of the filler dispersion, and significantly suppressed conductivity and loss. Activation energies of GO/PVDF and GO@PVP/PVDF nanocomposites are calculated as 1.247 eV and 0.435 eV, respectively, indicating that the presence of PVP layer on the GO surface reduces the relaxation activation energy and makes the relaxation occurrence at low temperatures.

Linear and nonlinear dielectric properties of nanocomposites based on the organic ferroelectric of diisopropylammonium bromide

ABSTRACTThe present work aims at investigating linear and nonlinear dielectric properties of nanocomposites based on diisopropylammonium bromide (C6H16NBr, DIPAB) embedded into Al2O3 films having honeycomb structure with pores of 100 nm in diameter, and into opal matrices with three-dimensional structure containing pores of 100 and 60 nm. The obtained results indicated the shift of Curie point toward lower temperatures for DIPAB in porous aluminum oxide and the appearance of two phase transitions, detected upon heating and cooling for DIPAB in opal matrices. In addition, a ferroelectric phase was found to form between these two phase transitions without significant change of Curie temperature.