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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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A New Process to Synthesize CrSe Thin Films with Nanosize by CBD Method
摘要： In this study, CrSe thin films were produced by using a new variation of chemical bath deposition (CBD) on glass substrates at different pH values, namely pH: 8, 9, 10 and 11. Some optical properties of these films including T% (transmittance), R% (reflectance), n (refractive index), k (extinction coefficient) and ?1 and ?2 (real and imaginary parts of dielectric constants) for pH: 8, 9, 10 and 11 were found as (82.89, 80.00, 78.54, 79.05%), (3.76, 5.32, 4.08, 5.44), (1.48, 1.59, 1.48, 1.60), (0.055, 0.079, 0.127, 0.116) and (1.33, 1.47, 1.21,1.52) and (0.87, 0.33, 0.12, 0.14) at 550 nm wavelength. Surface morphologies of thin films were examined by SEM. Film thicknesses were measured to be 34, 44, 50 and 104 nm by AFM, and the optical band gap (Egap) were calculated as 3.14; 3.72; 3.71 and 3.74 eV for pH: 8, 9, 10 and 11, respectively. Optical conductivity variation of CrSe thin films were calculated as a function of frequency for pH: 8, 9, 10 and 11, respectively. The usage areas of these films in optoelectronic applications were discussed.
关键词： Thin Film,CBD Method,Optical density,CrSe,Optical conductivity
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Preparation and Characterization of Epoxy and Hollow Ceramic Spheres Composites
摘要： High crash strength and high thermal conductivity hollow ceramic sphere with external diameters between 250 and 420 micrometers were produced by firing green bodies prepared in a fluidized reactor at room temperature. Then these spheres were bonded together by epoxy resin to produce composites with very high filler concentration but light weight. The dielectric, thermal and mechanical properties of the composites were investigated. Because the component in the raw materials of hollow ceramic spheres is varied, the corresponding composites have tunable permittivity and dielectric loss. In the composites, hollow ceramic spheres are nearly close packed, which can be observed by optical microscope. The novel close packed structure of these spheres endows the composites with highly efficient pathways for heat dissipation and reliable framework of bearing compressive loading. The surfaces of the spheres were modified by 1wt. % silane coupling agent, KH-560, before combining with epoxy resin in order to improve their chemical compatibility with epoxy resin. With TGA results, we can see that the epoxy resin in the composites has a low percentage of mass ratios and thus plays a role as binder to combine neighboring hollow ceramic spheres together. The results demonstrate improvement of dielectric and thermal conducting properties of epoxy resin, and feasibility of extending its working ranges in both compression strength and temperature as a multifunctional material in insulating area.
关键词： Compressive strength,Thermal conductivity,Composites,Ceramic spheres
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - High Voltage Electrical Properties of Epoxy / h-BN Microcomposites
摘要： Two high voltage properties – DC conductivity and AC breakdown strength – of epoxy composites filled with 30 wt% of micron sized hexagonal boron nitride (h-BN) are discussed in comparison to neat epoxy. The influence of h-BN upon the field dependence of DC conductivity has been studied up to 18 kV/mm. The addition of h-BN does not lead to a modification of conduction mechanisms: the J-V characteristics show an ohmic behavior at low fields and a space charge limited current (SCLC) at higher fields for both neat epoxy and composite. However, the addition of 30 wt% h-BN reduces the overall electrical conductivity and increases the threshold voltage between ohmic and SCLC regions, leading to a significant modification of electrical conductivity within the field range compared to neat epoxy. AC breakdown strength is enhanced for epoxy – h-BN composites while generally speaking the addition of micro fillers in an epoxy matrix tends to decrease it.
关键词： DC conductivity,electrical conduction mechanisms,epoxy composites,hexagonal boron nitride,AC breakdown strength
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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Impurity-derived <i>p</i> -type conductivity in cubic boron arsenide
摘要： Cubic boron arsenide (c-BAs) exhibits an ultrahigh thermal conductivity (j) approaching 1300 Wm(cid:2)1 K(cid:2)1 at room temperature. However, c-BAs is believed to incorporate high concentrations of crystal imperfections that can both quench j and act as sources of unintentional p-type conductivity. Although this behavior has been attributed to native defects, we show here, using optical and magnetic resonance spectroscopies together with first-principles calculations, that unintentional acceptor impurities such as silicon and/or carbon are more likely candidates for causing the observed conductivity. These results also clarify that the true low-temperature bandgap of c-BAs is 0.3 eV higher than the widely reported value of (cid:3)1.5 eV. Low-temperature photoluminescence measurements of c-BAs crystals reveal impurity-related recombination processes (including donor-acceptor pair recombination), and electron paramagnetic resonance experiments show evidence for effective mass-like shallow acceptors. Our hybrid density functional calculations indicate that native defects are incapable of giving rise to such signals. Instead, we find that group-IV impurities readily incorporate on the As site and act as shallow acceptors. Such impurities can dominate the electrical properties of c-BAs, and their influence on phonon scattering must be considered when optimizing thermal conductivity.
关键词： thermal conductivity,first-principles calculations,p-type conductivity,photoluminescence,impurities,cubic boron arsenide,electron paramagnetic resonance
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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Preparation, characterization and electrical behaviors of PEDOT:PSS-Au/Ag nanocomposite thin films: an ecofriendly approach
摘要： Structure, morphology and electrical behaviors of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) or PEDOT:PSS thin films are investigated in the presence of protein-mediated green chemically synthesized positively charged gold and silver nanoparticles. The pure and PEDOT:PSS nanocomposite thin films are prepared by spin coating method. The presence of both nanoparticle and polymer is confirmed from X-ray diffraction, whereas composite formation is confirmed from Raman and FTIR spectroscopy. Atomic force microscopy (AFM) images show the surface morphologies of both pure and composite films, whereas average film thicknesses are obtained from AFM and X-ray reflectivity analysis. The presence of electrostatic interaction between the positively charged metallic nanoparticles and negatively charged PSS chains leads to the electrostatic shielding between cationic PEDOT and anionic PSS, which favors better charge transfer through PEDOT–PEDOT conducting paths. The increase in electrical conductivity is visualized from the current–voltage (I–V) curves, which show that the conductivity is relatively higher in the presence of silver than gold nanoparticles in the composite thin films. The conductivity of nanocomposite films is approximately five to six times enhanced in comparison with the pristine PEDOT:PSS thin films.
关键词： FTIR spectroscopy,PEDOT:PSS-Au/Ag thin films,AFM,UV–Vis,Nanocomposites,Conductivity
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