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Abstract: Poly(2-thiophen-3-yl-malonic acid)/Fe3O4 nanocomposite was synthesized by the precipitation of Fe3O4 in the presence of poly(2-thiophen-3-yl-malonic acid) (PT3MA). Characterizations of the nanocomposite were performed by XRD, FT-IR, TEM, TGA, AC/DC conductivity and dielectric measurements. The capping of PT3MA around Fe3O4 nanoparticles was confirmed by FTIR spectroscopy, the interaction being between bridging oxygen of the carboxylate and the nanoparticle surface through bidentate binding. The crystallite particle sizes of 6±3nm and 7±3nm were obtained from XRD line profile fitting and from TEM image analysis respectively, and they are in good agreement with each other. Magnetization measurements revealed that PT3MA coated magnetite particles do not saturate at higher fields. The material showed superparamagnetic character as revealed by the absence of coercivity and remnant magnetization. Magnetic particle size was calculated as 7.3±1.0nm from the mean magnetization term in the Langevin function which is also in conformity with the values determined from TEM micrographs and XRD line profile fitting. The TEM particle size analysis of the nanoparticles revealed the presence of a slightly modified magnetically dead nanoparticle surface. AC and DC conductivity measurements were performed to elucidate the electrical conduction characteristics of the product. [Copyright &y& Elsevier]

Abstract: Al2O3–17vol.% SiC nanocomposites were prepared by powder mixture of submicrosized α-Al2O3, nanosized γ-Al2O3 and different nanosized β-SiC. Materials were sintered by spark plasma sintering (SPS) technique at two temperatures (1400–1550°C) and their electrical conductivity and mechanical properties were investigated. High-density composites have been achieved even at the lowest sintering temperatures and the microstructure characterization shows SiC particles located both within the Al2O3 matrix grains and/or at the Al2O3 grain boundaries. It has been demonstrated that microstructure tailoring is possible by suitable selection of starting materials and fast sintering by SPS. Accurate design of nanocomposites microstructures allows obtaining moderately conductive (<100Ωcm) or insulating (108 Ωcm) materials while the chemical composition is similar. [Copyright &y& Elsevier]

Abstract: Composites of MWCNTs having each three different levels of matrix viscosity with five different polymers (polyamide 12, polybutylene terephthalate, polycarbonate, polyetheretherketone and low density polyethylene) were melt mixed to identify the general influence of matrix viscosity on the electrical properties and the state of MWCNT dispersion. Huge differences in the electrical percolation thresholds were found using the same polymer matrix with different viscosity grades. The lowest percolation thresholds were always found in the composites based on the low viscosity matrix. The state of primary MWCNT agglomerate dispersion increased with increasing matrix viscosity due to the higher input of mixing energy. TEM investigations showed nanoagglomerated structures in the low viscosity samples which are obviously needed to achieve low resistivity values. The effect of nanotube shortening was quantified using two different viscosity grades of polycarbonate. Due to the higher mixing energy input the nanotube shortening was more pronounced in the high viscosity matrix which partially explains the higher percolation threshold. [Copyright &y& Elsevier]

Abstract: Electrically conductive and thermally stable polyamide 6 (PA 6) nanocomposites were prepared through one-step in situ polymerization of ε-caprolactam monomer in the presence of electrically insulating and thermally unstable graphene oxide (GO) nanosheets. These nanocomposites show a low percolation threshold of ∼0.41vol.% and high electrical conductivity of ∼0.028S/m with only ∼1.64vol.% of GO. Thermogravimetric analysis and X-ray photoelectron spectroscopy results of GO before and after thermal treatment at the polymerization temperature indicate that GO was reduced in situ during the polymerization process. X-ray diffraction patterns and scanning electron microscopy observation confirm the exfoliation of the reduced graphene oxide (RGO) in the PA 6 matrix. The low percolation threshold and high electrical conductivity are attributed to the large aspect ratio, high specific surface area and uniform dispersion of the RGO nanosheets in the matrix. In addition, although GO has a poor thermal stability, its PA 6 nanocomposite is thermally stable with a satisfactory thermal stability similar to those of neat PA 6 and PA 6/graphene nanocomposite. Such a one-step in situ polymerization and thermal reduction method shows significant potential for the mass production of electrically conductive polymer/RGO nanocomposites. [Copyright &y& Elsevier]

Abstract: A comparative study of the influence of processing route on polyurethanes (PUs)/multiwalled carbon nanotube (MWCNT) composites mechanical and electrical properties and also morphology was undergone employing two differentiated processing methods, solvent casting and buckypaper infiltration, for producing PU composites with low, medium and high mass fractions of acid treated MWCNT, and with no covalent linkages between the matrix and the nanotubes. As for example, with a MWCNT mass fraction of ∼18wt.% the second method produced stiffer (270MPa), lighter (948kgm−3) and more electrically conductive (1.8Scm−1) composite while the first one gave softer (111MPa) and more ductile (141%) materials. These properties differences are related to the different PU/MWCNT dispositions obtained through each synthesis route. Nanotubes percolating concentration is found to be crucial on composite properties evolution and a preferential interaction of MWCNT with PU hard segments is observed for solvent cast composites. [Copyright &y& Elsevier]

Abstract: Four dispersion methods were used for the preparation of vapour grown carbon nanofibre (VGCNF)/epoxy composites. It is shown that each method induces certain levels of VGCNF dispersion and distribution within the matrix, and that these have a strong influence on the composite electrical properties. A homogenous VGCNF dispersion does not necessarily imply higher electrical conductivity. In fact, it is concluded that the presence of well distributed clusters, rather than a fine dispersion, is more important for achieving larger conductivities for a given VGCNF concentration. It is also found that the conductivity can be described by a weak disorder regime. [Copyright &y& Elsevier]

As a type of thin film, two dimensional (2D) reticulate architectures built of freestanding single-walled carbon nanotube (SWCNT) bundles are suitable for scalable integration into devices and nanocomposites for many applications. The superior properties of these films, such as optical transparency, unique electrical properties and mechanical flexibility, result not only from the outstanding properties of individual SWCNTs but also from the collective behavior of the individual tubes, with additional properties arising from the tube-tube interactions. In this review, the synthesis, structure and fundamental properties, such as conductivity, transparency, optical nonlinearity and mechanical performance, of 'freestanding SWCNT bundle network' thin films and nanocomposites, as well as their application as supercapacitors are highlighted. Some long-standing problems and topics warranting further investigation in the near future are addressed. [ABSTRACT FROM AUTHOR]

Abstract: Metal-supported solid oxide fuel cells (SOFCs) are one of the most promising candidates for applications in power plants as well as in portable applications due to their good mechanical and thermal properties. A Ni-supported SOFC that consists of a metal support (Ni, ∼180 μm), an anode functional layer (Ni-yttrium stabilized zirconia YSZ, ∼15 μm), an electrolyte (YSZ, ∼5 μm), and a nanocrystalline La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode is prepared. A nanocrystalline LSCF synthesized with ethylenediaminetetraacetic acid, citric acid, and inorganic nanodispersants, is used as an in situ sinterable cathode. The Ni-supported SOFC with nanocrystalline LSCFs is operated without a high temperature treatment for cathode sintering. The cell exhibits the maximum power density of 580 mW cm−2 at 780 °C. A current treatment for 8 h (0.5 A cm−2 at 780 °C) enhances the interfacial contact between the cathode and the electrolyte. After the current treatment, the maximum power density at 730 °C increase by 1.6 times from 260 mW cm−2 to 390 mW cm−2. The ohmic resistance (R ohm) at 730 °C decreases from 0.43 Ω cm2 to 0.21 Ω cm2 and the charge transfer polarization at 0.7 V decreases from 0.42 Ω cm2 to 0.30 Ω cm2 due to lowered interfacial resistance between the cathode and the electrolyte. However, the mass transfer polarization increases from 0.09 Ω cm2 to 0.17 Ω cm2, which may result from the morphological change in the porous microstructure of the Ni support. The current treatment of the Ni-supported SOFC with in situ sintered LSCFs exhibit an increment in fuel cell performance due to the lowered ohmic resistance, which is beneficial for simple and mechanically improved fabrication and operation of metal-supported SOFCs. [Copyright &y& Elsevier]

Pyrrole is the subject of numerous studies due to its good environmental stability. The synthesis of Polypyrrole-Multi Wall Carbon Nanotubes (MWCNT) conductive nanocomposite was carried out by oxidative polymerization of pyrrole using Ferric Chloride. The structure resulted into the complex nanotube structure. Thus prepared nanocomposite material was characterized via X-Ray Diffraction (XRD) analysis, morphological properties (SEM), FTIR analysis, and conductivity measurements by two probe method. The concentrations of MWCNT in the composites were kept at 0, 1.5 and 3%. As concentration of the MWNT increased, the conductivity was found to be increased. The concentration of MWCNT in polypyrrole was optimized on the basis of best conductivity values. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by the method of solution mixing/casting. The dispersity of the MWCNTs in the PVDF-TrFE matrix was investigated using transmission electron microscopy (TEM), revealing that MWCNT are well distributed in the PVDF matrix. Both individual and agglomerations of MWCNT's were evident. The electrical properties were characterized by ac conductivity measurements. The conductivity was found to obey a percolation-like power law with a percolation threshold below 0.30 wt. %. The electrical conductivity of the neat PVDF-TrFE could be enhanced by seven orders of magnitude, with the addition of only 0.3 wt. % MWCNTs, suggesting the formation of a well-conducting network by the MWCNT's throughout the insulating polymer matrix. The intercluster polarization and anomalous diffusion models were used to explain the dielectric behaviors of the composites near the percolation threshold, and the analyses of ac conductivity and dielectric constant imply that the intercluster polarization is more applicable to our systems. [ABSTRACT FROM AUTHOR]

Abstract: Multi-walled carbon nanotube (MWCNT)/MnO2 supercapacitor electrodes containing MnO2 nanoflakes in the MWCNT network are fabricated through the oxidation of manganese acetate with poly(4-styrenesulfonic acid) (PSS) dispersed MWCNTs. The structural evolution of the electrodes under charge/discharge (reduction/oxidation) cycles and its impact on the electrodes’ electrochemical properties are evaluated. Structural evolution involves the dissolution of MnO2 upon reduction, the diffusion of the reduced Mn species from the MWCNT network toward the electrolyte solution, and the deposition of MnO2 on the electrode surface upon oxidation. Electrode structural changes, including the electrode dissolution and the growth of the MnO2 crystals, are scan rate dependent and have deteriorating effect on the electrode''s electrochemical properties including the specific capacitance and cyclic stability. [Copyright &y& Elsevier]

Abstract: Graphene, whose structure consists of a single layer of sp2-hybridized carbon atoms, provides an excellent platform for designing composite nanomaterials. In this study, we have demonstrated a facile process to synthesize graphene–multiwalled carbon nanotube (MWCNT) composite. The graphene–MWCNT composite material is endowed with a large electrochemical surface area and fast electron transfer properties in Fe(CN)6 3−/4− redox species. A graphene–MWCNT composite modified electrode exhibits good performance in terms of the electrocatalytic reduction of H2O2; a sensor constructed from such an electrode shows a good linear dependence on H2O2 concentration in the range of 2×10−5 to 2.1×10−3 molL−1. The detection limit is estimated to be 9.4×10−6 molL−1. This study provides a new kind of composite modified electrode for electrochemical sensors. [Copyright &y& Elsevier]

Commonly, the polymers are dielectric materials. A method to improve the polymer materials electric properties is the addition of the particles with superior electric parameters into the unsaturated matrix. In this way, multiwall carbon nanotubes (MWCNT) were used, as pristine material. A new dispersion technology of the pristine MWCNT was experimented. In order to relieve physical and chemical processes that induce the improved electrical properties to polymer/MWCNT nanocomposite material, the results obtained for different MWCNT concentrations (0,10%; 0,15%; 0,20%) are comparative presented. MWCNTs optimum dispersion concentration was assessed by a rheological analysis measuring the viscosity of polymer/MWCNT nanocomposite precursor system. The nanoscale effect appeared at carbon nanotubes proximity with concentration increasing and also the technological process contribution is demonstrated by precursor viscosity variation. In this paper, a comparative study of precursor systems viscosity variation at three different concentrations and nanocomposite materials electrical conductivity is presented. The critical analysis of the obtained results demonstrates MWCNT optimum concentration of 0,175%. [ABSTRACT FROM AUTHOR]

Abstract: In this work, composite nanostructures of BiFeO3 (BFO) and poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymers were fabricated using porous anodic aluminum oxide (AAO) templates by sol–gel and vacuum infiltration methods. Scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HRTEM) were employed to investigate the morphology of composite nanostructures. It was found that a double-layer nanostructure with inner P(VDF-TrFE) copolymers for high insulating property and outer BFO nanotubes for mechanical supporting. The leakage current density of BFO/P(VDF-TrFE) composite nanostructures is four orders of magnitude lower than that of BFO under ±8MV/m. It is suggested that the facile approach has great potential in multiferroic devices. [Copyright &y& Elsevier]

The article discusses the photocatalytic activity of mesoporous titania (TiO2)-alumina (Al2O3) nanocomposites produced from a sol-gel method. It mentions the key role of adsorption in subsequent photocatalytic decomposition of organic molecules. Moreover, titania's spectral range of photocatalytic activity can be extended to the visible range by forming multiphase nanostructured composites made up of two semiconductors with different kinds of conductivity.

In the framework of coupling surface/interface theory, a self-consistent scheme of effective field method is proposed to solve the dynamic electro-elastic properties of piezoelectric nanocomposites. The piezoelectric matrix with randomly distributed piezoelectric nano-fibers is reduced to the problem of an effective piezoelectric medium with a typical piezoelectric nano-fiber. The effective wave number and piezoelectrically stiffened elastic modulus are obtained on the basis of the derived imperfect interface conditions around the piezoelectric nano-fiber. Analyses show that the energy at the surface/interface shows significant effect on the dynamic electro-elastic properties, and the effect under different incident frequencies is discussed in details. [ABSTRACT FROM AUTHOR]

The use of nanocomposites as dielectric materials is expected to lead to improved electrical performance. However, recent research has shown that moisture absorption can cause a deterioration in the electrical performance of nanocomposites. Although it is generally accepted that hydroxyl groups attached to nanoparticle surfaces are the main cause of moisture absorption, the impact of this absorption on the electrical properties of nanocomposites is still not fully understood. In this paper, a series of measurements, including thermogravimetric analysis, DC breakdown, surface potential decay and space charge, are conducted with the aim of determining the impact of moisture absorption on the electrical properties of polyethylene/silica nanocomposites. The results show that the loading ratio of nanosilica and the humidity of the conditioning environment determine the amount of absorbed moisture. According to the Zhuravlev model, the main contribution to the deterioration in electrical properties of nanocomposites comes from the large amount of moisture absorbed in multilayer form. It is found that the loading ratio of nanosilica is the most significant factor in reducing DC breakdown strength. [ABSTRACT FROM AUTHOR]

In this article, we have investigated the effect of nanocomposite gate dielectric layer built by alumina (Al2O3) and poly(4-vinyphenol) (PVP) with solution method which could enhance the dielectric capability and decrease the surface polarity. Then, we used modify layer to optimize the surface morphology of dielectric layer to further improve the insulation capability, and finally we fabricated the high-performance and low-voltage organic thin-film transistors by using this nanocomposite dielectric layer. The result shows that the devices with Al2O3:10%PVP dielectric layer with a modified layer exhibited a mobility of 0.49 cm2/Vs, Ion/Ioff ratio of 7.8 × 104, threshold voltage of − 1.2 V, sub-threshold swing of 0.3 V/dec, and operating voltage as low as − 4 V. The improvement of devices performance was owing to the good insulation capability, appropriate capacitance of dielectric layer, and preferable interface contact, smaller crystalline size of active layer. [ABSTRACT FROM AUTHOR]

Conjugated polymer poly(3,4-dioxyethylenthiofene) (PEDOT) has recently gained attention for room-temperature thermoelectric applications due to its low cost, safety and the possibility of easy processing. This makes it an interesting prospective alternative to tellurides commonly used around room temperature. Still, low thermoelectric efficiencies of polymers might be more easily increased, were a model of its transport properties available. The aim of this paper is to validate a model recently reported, making use of the concept of transport energy to frame the onset of transport properties reported over the last few years in the literature. To this aim, PEDOT and PEDOT-based nanocomposites embedding CuO nanoplatelets were prepared and analysed. We found that the model adequately fits the trends observed in pure PEDOT and in its nanocomposites. Transport and Fermi energy were verified to depend on the polymer oxidation level only,while the transport coefficient was found to be sensitive to PEDOT stacking and was modulated by the introduction of CuO nanoplatelets. [ABSTRACT FROM AUTHOR]

We report a successful approach for the fabrication and characterization of a fiber-optic sensor for ascorbic acid (AA) detection, using a molecularly imprinted polyaniline–Ag (PANI–Ag) nanocomposite layer based on the combined phenomena of surface plasmon resonance (SPR) and localized SPR (LSPR). The PANI–Ag nanocomposite is synthesized by an in situ polymerization process and AA imprints are prepared on the polymeric composite. The confirmation of the PANI–Ag nanocomposite and AA imprinting is performed using various characterization methods such as x-ray diffraction (XRD), UV–vis, Fourier transform infrared spectroscopy and scanning electron microscopy. From XRD, the size of Ag nanoparticles is analyzed. The absorbance spectra are recorded for samples of different concentrations of AA around the sensing region of the probe. An increase in peak absorbance wavelength with the increase in AA concentration is observed with a linear response for the concentration range from 10−8 M to 10−6 M. The sensor possesses a high sensitivity of 45.1 nm log−1 M near an AA concentration of 10−8 M. The limit of detection (LOD) and limit of quantification of the sensor are found to be 7.383 × 10−11 M and 4.16 × 10−10 M, respectively. The LOD of the sensor is compared to studies reported in the literature and is found to be the lowest. The sensor possesses several other advantages such as cost effectiveness, selectivity, and low response time (<5 s), along with abilities of remote sensing and online monitoring. [ABSTRACT FROM AUTHOR]

We have developed a facile, efficient, low cost and ‘green’ photochemical approach to preparing surfactant-free Pd nanoparticles and Pd-immobilized@acrylate photo-polymer films at room temperature, under air and without any additional treatment. The reaction system only includes a photo-initiator used as a generator of free radicals and a Pd(II) salt. In ethanol solution, the photochemical reduction of Pd(II) to Pd(0) generates very small metal particles with a narrow size distribution (2–4 nm). Furthermore, we have shown that the formation of Pd nanoparticles from a Pd(II) salt can be reversible thus allowing easy handling and safe storage with the possibility of generating the nanoparticles just before use. In the presence of an acrylate bifunctional monomer, Pd@polymer film was obtained through a ‘one-pot, one-step’ process resulting from a simultaneous photo-reduction of Pd(II) and photo-polymerization of acrylate units. The simultaneous generation of a 3D polymer network and of metal particles leads to a homogeneous distribution of Pd nanoparticles in the photo-polymer matrix with an average diameter of approximately 3.7 ± 1.1 nm. Such as-prepared Pd@polymer films were found to efficiently catalyze the Mizoroki–Heck reaction in the presence of only 0.9 mequiv. of supported palladium. The major interest of this arrangement is its recoverability and reusability, which makes it very attractive both from a practical and economical viewpoint. Finally, it is worth noting that this innovation offers a great advantage over concurrent methods in that it is simply generated within minutes, it is highly stable, and there is sharp monodispersity in the size of the Pd nanoparticles that can be stored for months without alteration of their physico-chemical properties and catalytic activity. [ABSTRACT FROM AUTHOR]

The advent of flexible optoelectronic devices has accelerated the development of semiconducting polymeric materials. We seek to replace conventional expensive semiconducting photodetector materials with our cost-effective composite system. We demonstrate in this work the successful fabrication of a photoconductive composite film of poly(3-hexylthiophene-2,5-diyl) (P3HT) mixed with NaYF4:Yb,Er nanophosphors that exhibited a ultrahigh photoresponse to infrared radiation. The high photocurrent measured was enabled by the unique upconversion properties of NaYF4:Yb,Er nanophosphors, where low photon energy infrared excitations are converted to high photon energy visible emissions that are later absorbed by P3HT. Here we report, a significant 1.10 × 105 times increment of photocurrent from our photoconductive composite film upon infrared light exposure, which indicates high optical-to-electrical conversion efficiency. Our reported work lays the groundwork for the future development of printable, portable flexible and functional photonic composites for light sensing and harvesting, photonic memory devices, and phototransistors. [ABSTRACT FROM AUTHOR]

We proposed a new type of low-cost and environmentally friendly photoconductive sensor, based on GaSe/graphite nanocomposite fully dry drawn on paper. The proposed fully-drawn nanocomposite sensors successfully utilize the unique combination of structural and electrical properties of a layered semiconductor and graphite. In spite of the relatively pure photosensitivity of the proposed photodetectors, we believe that this work is the first step for the further development and enhancement of extremely simple and low-cost paper-based dry drawn layered semiconductor/graphite nanocomposite sensors. [ABSTRACT FROM AUTHOR]

MxWO3(M=Na, K) nanoparticles were successfully synthesized using MBH4as a reducing agent in aqueous solution, followed by crystallization of amorphous precursors under calcination in H2(5 vol.%)/N2atmosphere at 600 °C. Then, it was post-graphenized by solvothermal method with different weight ratios. The synergistic effects could be observed in the composites. When 10 wt.% or more graphene were composed into MxWO3, the hybrid composite showed the higher electrical conductivity than those of uncoupled graphene and tungsten bronze alone. [ABSTRACT FROM AUTHOR]

The article discusses a study that developed an electrochemiluminescent immunosensor based on nanocomposites for the detection of Ochratoxin A. Topics discussed include the immobilization of the electrochemiluminescent emitters onto mesoporous, electrochemiluminescence radiation and response signal and advantages of the proposed electrochemiluminescent immunosensor.

Single-crystalline Si-based nanocomposites have become promising candidates for thermoelectric applications due to their prominent merits. Reducing the thermal conductivity κ without deteriorating the electrical properties is the key to improve their performance. Through non-equilibrium molecular dynamics simulations, we show that κ of single-crystalline Si-based nanocomposites can be reduced to the alloy limit by embedding various nanoinclusions of similar lattice constants but different lattice orientations or space symmetries with respect to the matrix. The surprisingly low κ is mainly due to the large acoustic phonon density of states mismatch caused by the destruction of lattice periodicity at the interfaces between the nanoinclusions and matrix, which leads to the substantial reduction of phonon group velocity and relaxation time, as well as the enhancement of phonon localization. The resulting κ is also temperature-insensitive due to the dominance of boundary scattering. The increase in thermal resistance induced by lattice structure mismatch mainly comes from the nanoinclusions and the channels between them and is caused by the enhanced boundary scattering at the interfaces parallel to the heat flux. Approaching the alloy limit of κ with potentially improved electrical properties by fillers will remarkably improve ZT of single-crystalline Si-based nanocomposites and extend their application. [ABSTRACT FROM AUTHOR]

We reported a scalable and modular method to prepare a new type of sandwich-structured graphene-based nanohybrid paper and explore its practical application as high-performance electrode in flexible supercapacitor. The freestanding and flexible graphene paper was firstly fabricated by highly reproducible printing technique and bubbling delamination method, by which the area and thickness of the graphene paper can be freely adjusted in a wide range. The as-prepared graphene paper possesses a collection of unique properties of highly electrical conductivity (340 S cm−1), light weight (1 mg cm−2) and excellent mechanical properties. In order to improve its supercapacitive properties, we have prepared a unique sandwich-structured graphene/polyaniline/graphene paper by in situ electropolymerization of porous polyaniline nanomaterials on graphene paper, followed by wrapping an ultrathin graphene layer on its surface. This unique design strategy not only circumvents the low energy storage capacity resulting from the double-layer capacitor of graphene paper, but also enhances the rate performance and cycling stability of porous polyaniline. The as-obtained all-solid-state symmetric supercapacitor exhibits high energy density, high power density, excellent cycling stability and exceptional mechanical flexibility, demonstrative of its extensive potential applications for flexible energy-related devices and wearable electronics. [ABSTRACT FROM AUTHOR]

Nanocomposites have unprecedented potential for conductivity-based damage identification when used as matrices in structural composites. Recent research has investigated nanofiller alignment in structural composites, but because damage identification often requires in-plane measurements, percolation and conductivity transverse to the alignment direction become crucial considerations. We herein contribute indispensable guidance to the development of nanocomposites with aligned nanofiller networks and insights into percolation trends transverse to the alignment direction by studying the influence of alignment on transverse critical volume fraction, conductivity, and rate of transition from non-percolating to percolating in three-dimensional carbon nanotube composite systems. [ABSTRACT FROM AUTHOR]

We present electronic band structure, Gibbs free energy of formation, and electric field modulation calculations for silicane nanoribbons (NRs), i.e., completely hydrogenated or fluorinated silicene NRs, using density functional theory. We find that although the completely hydrogenated silicene (H-silicane) sheet in the chair-like configuration is an indirect-band-gap semiconductor, a direct band gap can be achieved in the zigzag H-silicane NRs by using Brillouin-zone folding. Compared to H-silicane NRs, the band gaps of completely fluorinated silicene (F-silicane) NRs reduce at least by half. For all silicane NRs considered here, the Gibbs free energy of formation is negative but shows different trends by changing the ribbon width for H-silicane NRs and F-silicane NRs. Furthermore, by analyzing the effect of transverse electric fields on the electronic properties of silicane NRs, we show that an external electric field can make the electrons and holes states spatially separated and even render silicane NRs self-doped. The tunable electronic properties of silicane NRs make them suitable for nanotechnology application. [ABSTRACT FROM AUTHOR]

Three-phase graphene/BaTiO3/polyvinylidene fluoride composites films are prepared with a simple solution-cast method. The effects of graphene oxides (GOs) and reduced graphene oxides (RGOs) on the dielectric behavior of the three-phase composites are investigated at elevated electric field up to 150 kV/mm. BaTiO3 nanoparticles isolate the graphene nanosheets, leading to much higher percolation threshold. The introduction of both RGOs and GOs increases the leakage current in the three-phase composites at elevated electric field. The positive-up-negative-down measurements indicate that the switched polarization slightly increases with the addition of RGOs or GOs and is much smaller than the remnant polarization obtained from the P-E loops. [ABSTRACT FROM AUTHOR]

One major challenge for engineering functional nanocomposites is how to tune the geometry structure and control the chemical composition. We demonstrate here that columnar nanocomposite films can be grown by using alternate deposition of La2/3Sr1/3MnO3 and V2O3 on LaAlO3 (111). A solid state reaction, rather than simple spinodal decomposition, dictates the nanocomposite structure, chemical composition, and functionality. By controlling the deposition time ratio of the two compounds, the physical properties of the composite films can be tuned, thus providing a flexible way to tailor nanocomposites for advanced functionality. [ABSTRACT FROM AUTHOR]

We report microwave spectroscopy studies of graphene-based polymer-matrix composite materials subject to uniaxial elongation. The samples were prepared via shear mixing under the same thermal processing conditions of amorphous styrene butadiene rubber (SBR) with quartz grains on the order of micrometers in size and/or graphene sheets with thickness 10-20 nm and average lateral size 200 μm. An important result is the observation of a significant increase (up to 25%) in the effective microwave permittivity of hybridized nanocomposites comprising both quartz and graphene compared to the nanocomposites with quartz only. We suggest that the coating of quartz grains by graphene sheets is the most likely origin of this synergetic effect. In all cases, we also observe that the permittivity spectrum is unaffected by strain up to 8%. By examining the mechanical response, it is shown that the elasticity network of SBR polymer chains is significantly affected in the rubbery state by filling SBR with graphene and quartz particles. [ABSTRACT FROM AUTHOR]

The strain-mediated magnetocapacitance (MC) of 1–3-type vertical ferroelectric–ferromagnetic nanocomposite films epitaxially grown on different cubic substrates is theoretically calculated using the nonlinear thermodynamic theory combined with elastic theory. The dependences of relative dielectric constant and strain sensitivity of permittivity for the ferroelectric film on the in-plane and out-of-plane misfit strains are obtained. Our results show that the MC effect strongly depends on the in-plane misfit strain and ferromagnetic volume fraction in the nanocomposite films. The calculated MC for the BaTiO3–CoFe2O4 nanocomposite film grown on the SrTiO3 substrate is consistent with the experimental result. Furthermore, a giant MC, which is enhanced by 1–2 orders of magnitude than those reported in experiments, can be obtained for the BaTiO3–CoFe2O4 system grown on the MgO substrate near the transition from the aa-phase to the r-phase. Our result provides a new method for the design of multiferroic nanocomposites with colossal MC effect by optimizing the ferromagnetic phase and substrate types to realize their applications in magnetic-field-controlled electric devices, such as magneto-oscillators, magnetovaractors and magnetoelectric sensors. [ABSTRACT FROM AUTHOR]

Nanocomposites of aligned multi-walled carbon nanotubes (CNTs) embedded in a polymer matrix yield a unique combination of thermal and electrical properties and mechanical strength. These properties are intimately related to the composite nanostructure and to the growth and processing conditions. The alignment of the tubes, the filling fraction and the contact junction between the nanotubes are key parameters controlling the composite electrical conductivity. For this purpose, a full description of the composite nanostructure is required. Among the non-destructive scanning probe techniques, scanning spreading resistance microscopy is found to be a powerful technique in identifying the carbon nanotubes with true nanometer resolution, thus competing with SEM and TEM imaging. Additionally, the technique provides valuable information about the electrical conduction mechanism within the composite structure. Indeed, by using a controlled contact force and an appropriate model of conduction at the nanoscale, the tip–CNT contact resistance, the CNT intrinsic resistance and the CNT–epoxy–CNT resistance junction are evaluated. This latter is found to be the factor controlling the overall electrical conductivity of the composite. [ABSTRACT FROM AUTHOR]

We demonstrate a magnetoelectric nanocomposite, LiNbO3-CoFe2O4 (LNO-CFO), consisting of rhombohedral R3c LNO and R3m CFO phases. It is characterized by a maximum inverse magnetoelectric coefficient of 6.5 Oe cm·V-1 measured in a 106 V/m electric field, and a magnetic field dependent Vogel-Fulcher-like relaxation characterized by a relaxation time τ=τ0exp(-ΔH/k(Tm-TvfH)), τ0=29.66 s, ΔH=1.06 eV, TvfH represents the magnetic field-dependent Vogel-Fulcher temperature. The activation energy equals the activation energy of oxygen vacancy diffusion in niobate-based crystals. The room temperature electric field-induced magnetization change relaxes as τ=18.05 s. [ABSTRACT FROM AUTHOR]

The research on dielectric frequency response of oil-paper composite insulation modified by nanoparticles has been carried out in order to seek possible way to improve insulation properties thereof. Before and after nanoparticles being added, the dielectric frequency responses of oil-paper composite insulation with different moisture contents at different temperatures have been measured within the frequency from 0.1 mHz to 1 MHz. The Cole-Cole relaxation model has been used to analyzing the measured data. The results show that the variation rules of insulation condition can be indicated by the parameters of relaxation model. By adding nanoparticles, a new low frequency relaxation appeared. [ABSTRACT FROM AUTHOR]

The influence of moisture on the dielectric properties of different types of poly (ethyleneco- butyl acrylate) filled with alumina nanoparticles was systematically investigated by varying the type of aluminum oxide, particle surface treatment and filler content (2, 6 and 12 wt%). The nanoparticles were either unmodified or surface-treated with either aminopropyl triethoxysilane or octyltriethoxy silane. The complex permittivity was measured with an IDA200 dielectric spectroscopy analyzer at applied voltage of 200 Vpeak with frequencies varying between 1 mHz and 1 kHz. The measurements were performed at 25°C and relative air humidities of 24, 54 and 86 %. In order to expand the frequency range the HP 4284A precision LCR meter was used for measuring sample impedance at the frequency range of 100 Hz to 1 MHz. From the frequency dependence of dielectric losses it can be seen that absorbed water plays a significant role in determining the dielectric properties of the nanocomposites. The magnitude of tan ? seems to be determined primarily by the particle size and filler content, while the peak frequency is mostly influenced by the amount of absorbed water and the type of particle coating. [ABSTRACT FROM AUTHOR]

The dielectric properties of poly (ethylene-co-butyl acrylate) with 13 wt% of butyl acrylate (EBA) filled with alumina nanoparticles were studied as a function of particle size, particle coating, filler content (2, 6 or 12wt%) and temperature. The particles were either unmodified or surface-treated with either aminopropyltriethoxy silane or octyltriethoxy silane. The complex permittivity was measured with frequencies varying between 1 mHz and up to 1 kHz at different temperatures (25, 45 and 65°C). Measurements were performed in dry conditions. From the dielectric spectroscopy measurements it can be seen that the tan ∂ for the dry samples is almost independent of the type of the particle coating used. It does, however, depend on the particle size, filler content and temperature. [ABSTRACT FROM AUTHOR]

An inverter surge resistant enameled wire was developed with innovative organic/inorganic nanocomposite insulating material by dispersing an inorganic material at a nanometer level. It successfully achieved satisfactory levels for both partial discharge resistance and coating film flexibility and strength. This product can maintain a voltage endurance of more than 1000 times as high as those offered by general enameled wires even after mechanical stress is applied. This paper describes how the product can dramatically improve the reliability of magnet wires and open the way for performance warrant of inverter-fed motors in actual operation up to a surge voltage around 1.5 kVp. [ABSTRACT FROM PUBLISHER]