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Investigation on Structural and Dielectric Properties of Silica Nanoparticles Incorporated Poly(Ethylene Oxide)/Poly(Vinyl Pyrrolidone) Blend Matrix Based Nanocomposites
摘要： Inorganic and organic materials based polymer nanocomposite (PNC) films, comprising silica (SiO2) nanoparticles as inorganic filler and the polymer blend of poly(ethylene oxide) (PEO) and poly(vinyl pyrrolidone) (PVP) as organic matrix (i.e., (PEO–PVP)-x wt% SiO2; x = 0, 1, 3 and 5) have been prepared by the solution-casting method. These PNC films are characterized by employing the scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier transform infrared (FTIR) spectroscopy, and the dielectric relaxation spectroscopy (DRS). The effect of SiO2 nanofiller on the spherulite and porous morphology, miscibility of the polymers, PEO crystallite size, the degree of crystallinity, polymer–polymer and polymer-nanoparticle interactions, and from 20 Hz to 1 MHz range dielectric and electrical dispersion behaviour and also the structural dynamics of these PNC materials have been investigated. The porous morphology, structures of miscible phases, and the PEO crystallite length greatly alter with the incorporation of merely 1 wt% SiO2 in the polymer blend matrix which further changes with the increase of nanofiller concentration up to 5 wt%. The real part of complex permittivity over the radio frequency range (20 kHz–1 MHz) for these PNC films is found about 2 and their dielectric loss tangent values below 0.03, at the room temperature, which are significantly low. The contribution of interfacial polarization effect at lower audio frequencies enhances the complex permittivity of these materials linearly in the range 2 to 4 with the decrease of frequency from 1 kHz to 20 Hz confirming their frequency tunable dielectric behaviour. The dielectric study of 3 wt% SiO2 containing PNC film in the temperature range 30–60 °C reveals its thermally activated dielectric characteristics, and the temperature dependent values of dielectric relaxation time and dc electrical conductivity obey the Arrhenius behaviour with activation energies in the range 0.2–0.3 eV. The dielectric and electrical parameters ascertain the promising applications of these PNC films in the development of novel electroactive functional materials, and also their use as the dielectric substrate and electrical insulating polymeric nanodielectrics for the fabrication of flexible-type naturally degradable organoelectronic devices.
关键词： Electrical conductivity,FTIR,XRD,Dielectric properties,Polymer nanocomposite
更新于2025-09-09 09:28:46
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High–pressure electrical conductivity and Raman spectroscopy of chalcanthite
摘要： The phase transitions and dehydration of chalcanthite were investigated by electrical conductivity and Raman spectroscopy at 1.0–24.0 GPa and 293–673 K in a diamond anvil cell. At ambient temperature, two secondary phase transitions were observed according to discontinuous changes in the slope of Raman shifts, full width at half maximum and electrical conductivities at (cid:1)7.3 and (cid:1)10.3 GPa. The dehydration temperatures were determined by the splitting of Raman peaks and changes in electrical conductivity as (cid:1)350 and (cid:1)500 K at respective (cid:1)3.0 and (cid:1)6.0 GPa. A positive relationship for chalcanthite between dehydration temperature and pressure is established.
关键词： dehydration,chalcanthite,phase transition,Raman spectroscopy,electrical conductivity
更新于2025-09-09 09:28:46
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Computational Investigation of the Morphology, Efficiency, and Properties of Silver Nano Wires Networks in Transparent Conductive Film
摘要： Random networks of silver nano wires have been considered for use in transparent conductive films as an alternative to Indium Tin Oxide (ITO), which is unsuitable for flexible devices. However, the random distribution of nano wires makes such conductive films non-uniform. As electrical conductivity is achieved through a percolation process, understanding the scale-dependency of the macroscopic properties (like electrical conductivity) and the exact efficiency of the network (the proportion of nano wires that participate in electrical conduction) is essential for optimizing the design. In this paper, we propose a computational method for identifying the representative volume element (RVE) of nano wire networks. This defines the minimum pixel size in devices using such transparent electrodes. The RVE is used to compute the macroscopic properties of films and to quantify the electrically conducting efficiency of networks. Then, the sheet resistance and transparency of networks are calculated based on the predicted RVEs, in order to analyze the effects of nano wire networks on the electrical and optical properties of conductive films. The results presented in this paper provide insights that help optimizing random nano wire networks in transparent conductive films for achieving better efficiencies.
关键词： electrical conductivity,representative volume element,silver nano wires,optical transmittance,transparent conductive films
更新于2025-09-09 09:28:46
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Thermal and electrical conductivity enhancement of solar glycol-water mixture containing MWCNTs
摘要： In this investigation, the authors describe the thermal conductivity, and electrical conductivity of solar glycol - water (50:50) mixture with MWCNTs. Gum Arabic was used as the surfactant to prepare a stable nanofluid suspension. The MWCNTs are dispersing with different volume concentrations of 0.2%, 0.4% and 0.6% prepared via a typical two-step methodology. The colloidal stability assessments were conducted through UV-vis spectrometer, zeta potential analyser, scanning electron microscopy analysis and pH metre. The maximum augmentation of thermal conductivity attained is (cid:1)21.46% at a loading of 0.6 vol.% of MWCNTs in SG - water mixture at 50(cid:3)C. However, the electrical conductivity of the prepared nanofluid linearly enhanced with increasing temperature. The electrical conductivity enhancements of (cid:1)62.19% at a loading of 0.6 vol.% of MWCNTs in SG – water mixture at 50?C. Results confirm that the SG-Water and MWCNTs based nanofluids can be used as a right replacement for the conventional liquids in various heat transfer applications.
关键词： Solar glycol,Thermal conductivity,Multiwalled carbon nanotubes,pH,Electrical conductivity
更新于2025-09-04 15:30:14
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Electrical Conductivity of Reduced Graphene Oxide Thin-Film Layers
摘要： This work deals with the research of the electric properties of thin film layer of reduced graphene oxide. A structure of graphene oxide (GO) is represented by randomly distributed on a surface of substrate small islets of graphene with sp2 hybridized bonds surrounded by wide areas with sp3 bonds functionalized by oxygen groups. When electrons are confined in two-dimensional materials, quantum-mechanically enhanced transport phenomena such as the quantum Hall effect can be observed. Reduced graphene oxide, consisting of an isolated single atomic layer of graphite, is an ideal realization of such a two-dimensional system, therefore the partly semiconductive properties could be observed.
关键词： electrical conductivity,quantum Hall effect,reduced graphene oxide,thin-film layers,sp2 hybridized bonds
更新于2025-09-04 15:30:14
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Physical Properties of Pure and Nano Ag Doped Liquid Crystalline Compounds Containing 1,3,4-Oxadizole Unit
摘要： Dielectric properties and other physical properties such as electrical conductivity (AC) and relaxation time or activation energy have been studied for two systems pure LC [V]6,6, [V]7,6, [V]8,6, [V]6,7, [V]7,7 and [V]8,7 and their doped with silver nanoparticles. The results show the increasing in real dielectric permittivity ? with increasing length terminal chain. So the real dielectric permittivity increasing with raising temperature. To compare between the values of (400) Hz and (4000) Hz we observe these values at the low frequency are larger than that in high frequency. Generally, one can see that the doping of Ag nano particles effectively reduced the permittivity of the LC materials with its large electric dipole moment. The electrical conductivity σ value for pure LC samples in general increases with increasing temperature. So we observed increasing of electrical conductivity values at high frequency. The time scale is discussed in terms of the Arrhenius plot. Generally, with increasing the temperature the time period that spends by molecules at the transition state will increase. The activation energy Ea values show the increase in the activation energy to the doped systems.
关键词： Dielectric permittivity,Doped liquid crystals,Liquid crystals,Relaxation time,Electrical conductivity,Activation energy,Silver nanoparticles
更新于2025-09-04 15:30:14
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Transport and complex modulus study of La0.7Ca0.3MnO3 perovskite manganite nano-compound with polypyrrole as host
摘要： The paper focuses on the facile synthesis of polypyrrole/La0.7Ca0.3MnO3 perovskite magnetic nano-composites synthesized by in situ chemical oxidation method using ammonium persulfate as oxidant. The morphology and crystal phase of the prepared samples were analyzed using SEM, TEM and XRD, respectively. Electrical conductivity, dielectric constant, dielectric loss, complex electric and impedance modulus studies were invested in the frequency range of 100 Hz–5 MHz at room temperature using AC impedance analyzer. The composites show frequency dependence with relaxation mechanism. The electric and impedance modulus analysis reveals the presence of non-Debye-type relaxation process and the effect of both grain and grain boundary on the transport properties of the composites.
关键词： Dielectric constant,Perovskite,Non-Debye relaxation,Electrical conductivity
更新于2025-09-04 15:30:14
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Microwave cavity perturbation of nitrogen doped nano-crystalline diamond films
摘要： Non-contact and non-destructive electrical conductivity measurements of nitrogen doped nano-crystalline diamond films have been demonstrated using a microwave cavity perturbation system. The conductivity of the films was controlled by simply varying the CH4 gas concentration during microwave plasma assisted chemical vapour deposition, thereby promoting the formation of sp2 carbon at the grain boundaries. The presence of sp2 carbon is verified through Raman spectroscopy, x-ray photoelectron spectroscopy and electron energy loss spectroscopy, while scanning electron microscopy confirms an increasing surface area for sp2 to form. The microwave cavity perturbation results show that the measured cavity quality factor varies with CH4 concentration. The extraction of conductivity is achieved through a depolarisation model, which must be considered when the sample is smaller than the cavity and through both electric and magnetic field perturbations. The microwave measurements are comparable to contacting and damaging measurements when the film conductivity is greater than the substrate, thus demonstrating an invaluable method for determining conductivity without the need for depositing any electrodes on the film.
关键词： non-contact,microwave dielectric spectroscopy,nano-crystalline diamond,electrical conductivity
更新于2025-09-04 15:30:14
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Influence of Pb on structure, optical and electrical properties of Zn1-XPbXS semiconductor compounds at low temperatures
摘要： Zn1-XPbXS (x = 0–0.4 in steps of 0.1) ternary semiconductor samples have been prepared by co-precipitation method. The structural, optical and electrical studies have been carried out on all these samples to understand the influence of Lead on these properties. X-ray diffractograms showed that all Zn1-XPbXS samples have poly-crystalline nature with Hexagonal phase. The room temperature optical absorption studies revealed that energy gap decreases with increase of Pb in Zn1-XPbXS compounds. The temperature-dependent conductivity, measured in the range 300–4 K, led to understand that the conduction mechanisms at 60 K and 30 K are different. The activation energies evaluated at low (300–60 K) and very low temperature (60–30 K) regions are 38.03–32.58 meV and17.99–13.56 meV respectively. Activation energy and conductivity of Zn1-XPbXS samples increase with the increase of Pb. The samples exhibited low freezing temperature points indicating the possibility of their use in low temperature device applications.
关键词： Ternary semiconductor,Energy gap,Activation energy,Electrical conductivity
更新于2025-09-04 15:30:14
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The study on negative dielectric properties of Al/PVA (Zn-doped)/p-Si (MPS) capacitors
摘要： In this research, PVA (doped with 7% Zn) was sandwiched between Al and p-Si as a polymer interfacial layer. Voltage and frequency effect on the real and imaginary components of complex dielectric constant (e0 and e00), electric modulus (M0 and M00), loss tangent (tan d) and electrical conductivity (r) of the MPS-type capacitor has been studied. Impedance spectroscopy method was used between 5 and 5000 kHz at room temperature. Almost all frequency-related parameters were found as quite susceptible, especially in the accumulation and depletion regions. These changes in real and imaginary components of dielectric properties in depletion region were attributed to the interface layer and dipole polarization, the existence of surface states (Nss) and their relaxation time (s), especially at low frequencies. But these changes in the accumulation region were attributed to the existence of interfacial layer and series resistance (Rs) of the capacitor owing to the voltage divided between them and capacitor. As a result, frequency, applied biases, interfacial polymer layer, polarization processes, Nss and Rs of the capacitor are more effective on the values of e0, e00, tan d, M0, M00 and r. Therefore, the effects of them must be considered in determining the dielectric parameters, electric modulus, conductivity and conduction mechanisms in the capacitors with and without an interfacial layer such as insulator/oxide, polymer, ferroelectric materials.
关键词： Electric modulus,Impedance spectroscopy method,Electrical conductivity,Negative dielectric properties
更新于2025-09-04 15:30:14