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Ion Transport in Laser-Induced Graphene Cation-Exchange Membrane Hybrids
摘要： Ion exchange membranes hybridized with laser-induced graphene (LIG) might lead to membranes with functional surface effects such as antifouling, antibacterial or joule heating, however, understanding the change in the electrical properties of the membrane is essential. Here we studied LIG-modified ion-exchange polymeric membranes using electrochemical impedance spectroscopy (EIS). The conductivity of the anionic sulfonated polyethersulfone membranes and the effective capacitance of the membrane-electrolyte interface were obtained by fitting the EIS spectra to an electrochemical equivalent circuit and compared to LIG-modified non-ionic polyethersulfone films. The transport selectivity (as relative permeability) of counter-ions (K+, Na+, Mg2+, Ca2+) across the membrane was quantified using the membrane’s conductivities obtained from the EIS measurements. The total ohmic resistance of the membrane was directly correlated to the polymer thickness, (with negligible contribution from the conductive LIG layer), thereby establishing EIS as a rapid, low-cost and non-invasive method to accurately probe substrate usage in LIG modification.
关键词： laser-induced graphene,electrochemical impedance spectroscopy,capacitance,ion exchange membranes,conductivity,ion transport
更新于2025-09-16 10:30:52
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Optical properties of fluidic defect states in one-dimensional graphene-based photonic crystal biosensors: visible and infrared Hall regime sensing
摘要： Advances in biotechnology are outpacing studies into the use of graphene in photonic biosensors due to its peculiar optical properties and the successful progress in the nanoscale integration of photonic crystals. Moreover, going beyond the usual Dirac cone approximation for graphene introduces nonlinear effects in graphene’s optics. In this work, by the use of the transfer matrix method, we investigate the effect of hopping parameter on the chemical and biosensing performance of a 1D defective photonic biosensor with a micro/nano?uidic channel as a central defect cavity for biological ?uids and gas molecules to ?ow while interacting with two graphene sheet deposited on silicon dioxide layers of the device. As low-weight molecules absorption on graphene’s surface could affect hopping energy of graphene which plays a signi?cant role in its optical conductivity obtained from the tight-binding model for the visible range, it will serve as a promising tool for the detection of gas and other analytes. We also examine the sensitivity of the defect modes to the changes of the refractive index of the biological ?uids under the in?uence of quantum Hall situation for graphene in terahertz (THz) regime. It is revealed that two defective modes with relatively different sensing properties are emerged within the band stop of the device. The results of this study are not reported elsewhere to the best of our knowledge.
关键词： photonic crystal,hopping parameter,terahertz,biosensor,optical conductivity,visible light,graphene,quantum Hall effect
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Guangzhou, China (2019.5.19-2019.5.22)] 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Design of Dynamically Tunable Broadband Polarization Converter in Terahertz Frequency Based on Graphene Strips
摘要： The phenomenon of soil salinization in semi-arid regions is getting amplified and accentuated by both anthropogenic practices and climate change. Land salinization mapping and monitoring using conventional strategies are insufficient and difficult. Our work aims to study the potential of synthetic aperture radar (SAR) for mapping and monitoring of the spatio-temporal dynamics of soil salinity using interferometry. Our contribution in this paper consists of a statistical relationship that we establish between field salinity measurement and InSAR coherence based on an empirical analysis. For experimental validation, two sites were selected: 1) the region of Mahdia (central Tunisia) and 2) the plain of Tadla (central Morocco). Both sites underwent three ground campaigns simultaneously with three Radarsat-2 SAR image acquisitions. The results show that it is possible to estimate the temporal change in soil electrical conductivity (EC) from SAR images through the InSAR technique. It has been shown that the radar signal is more sensitive to soil salinity in HH polarization using a small incidence angle. However, for the HV polarization, a large angle of incidence is more suitable. This is, under considering the minimal influence of roughness and moisture surfaces, for a given InSAR coherence.
关键词： interferometric synthetic aperture radar (InSAR) coherence,polarimetric synthetic aperture radar (SAR),soil salinity,Electrical conductivity (EC)
更新于2025-09-16 10:30:52
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Perspective: Ga <sub/>2</sub> O <sub/>3</sub> for ultra-high power rectifiers and MOSFETS
摘要： Gallium oxide (Ga2O3) is emerging as a viable candidate for certain classes of power electronics with capabilities beyond existing technologies due to its large bandgap, controllable doping, and the availability of large diameter, relatively inexpensive substrates. These applications include power conditioning systems, including pulsed power for avionics and electric ships, solid-state drivers for heavy electric motors, and advanced power management and control electronics. Wide bandgap (WBG) power devices offer potential savings in both energy and cost. However, converters powered by WBG devices require innovation at all levels, entailing changes to system design, circuit architecture, qualification metrics, and even market models. The performance of high voltage rectifiers and enhancement-mode metal-oxide field effect transistors benefits from the larger critical electric field of β-Ga2O3 relative to either SiC or GaN. Reverse breakdown voltages of over 2 kV for β-Ga2O3 have been reported, either with or without edge termination and over 3 kV for a lateral field-plated Ga2O3 Schottky diode on sapphire. The metal-oxide-semiconductor field-effect transistors fabricated on Ga2O3 to date have predominantly been depletion (d-mode) devices, with a few demonstrations of enhancement (e-mode) operation. While these results are promising, what are the limitations of this technology and what needs to occur for it to play a role alongside the more mature SiC and GaN power device technologies? The low thermal conductivity might be mitigated by transferring devices to another substrate or thinning down the substrate and using a heatsink as well as top-side heat extraction. We give a perspective on the materials’ properties and physics of transport, thermal conduction, doping capabilities, and device design that summarizes the current limitations and future areas of development. A key requirement is continued interest from military electronics development agencies. The history of the power electronics device field has shown that new technologies appear roughly every 10-12 years, with a cycle of performance evolution and optimization. The older technologies, however, survive long into the marketplace, for various reasons. Ga2O3 may supplement SiC and GaN, but is not expected to replace them.
关键词： MOSFETs,β-Ga2O3,rectifiers,power electronics,thermal conductivity,Gallium oxide,Ga2O3,doping,wide bandgap semiconductors,military electronics
更新于2025-09-16 10:30:52
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Dielectric and thermal behavior of 0.75BiFeO3-0.25BaTiO3 filled ethylene vinyl acetate Composites
摘要： Bismuth ferrite-Barium Titanate (BFO-BT) filled ethylene-vinyl acetate copolymer (EVA) composites have been processed by solution casting technique followed by compression molding. The effects of BFO-BT on structural, thermal and dielectric behaviour of the composites have been investigated using X-ray diffraction, field emission scanning electron microscopy, thermal analysis (DSC, TGA) and impedance analyser. As analysed by XRD and DSC analyses, with increase in BFO-BT content the crystallinity of EVA matrix decreases. BFO-BT has great effect on higher thermal stability of the composites. EVA/ BFO-BT composites exhibit significantly enhanced relative dielectric permittivity (εr =182) near the percolation limit of about 30 phr BFO-BT loading at 25° C and 1kHz frequency. With 30 phr BFO-BT loading, the dielectric loss of the composite shows only an approximately 2-fold increase i.e., from 0.04 to 0.091. The capacitance and resistance of grains is found from the exploratory Nyquist plots with the assistance of an electrical circuit. A cautious examination of the experimental complex impedance plots and model fitted plots is contemplated which fulfilled the precision of the information tentatively. With enhanced dielectric properties and thermal stability, the BFO-BT filled EVA composite system can be used for solar cells and energy saving devices.
关键词： Composites,Nyquist plots,Dielectric,Conductivity,Ethylene Vinyl Acetate,Bismuth Ferrite-Barium Titanate
更新于2025-09-12 10:27:22
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Optical and Electrical Properties of Double-Walled Carbon Nanotube/Polyaniline Composite
摘要： Nanocomposites of polyaniline loaded with different weight-fractions of double-wall carbon nanotubes were fabricated by in situ polymerizations of the polyaniline in the presence of double-wall carbon nanotubes. The composition of the nanocomposites is examined by X-ray diffraction and scanning electron microscopy techniques. The functionality of the synthesized composites was studied by electrical conductivity and fluorescence analyses. The dc conductivity of polyaniline was increased by introducing 2.5 wt% of DWCNTs into polyaniline matrix. The fluorescence emission from the double-wall carbon nanotubes/polyaniline showed a broad emission range in the visible region between 350 and 560 nm with appreciable enhancement in the intensity at 434 nm.
关键词： Polyaniline,Conductivity,Fluorescence,Double-wall carbon nanotubes,Composite
更新于2025-09-12 10:27:22
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The Growth of Ga2O3 Nanowires on Silicon for Ultraviolet Photodetector
摘要： We investigated the effect of silver catalysts to enhance the growth of Ga2O3 nanowires. The growth of Ga2O3 nanowires on a P+-Si (100) substrate was demonstrated by using a thermal oxidation technique at high temperatures (~1000 °C) in the presence of a thin silver film that serves as a catalyst layer. We present the results of morphological, compositional, and electrical characterization of the Ga2O3 nanowires, including the measurements on photoconductance and transient time. Our results show that highly oriented, dense and long Ga2O3 nanowires can be grown directly on the surface of silicon. The Ga2O3 nanowires, with their inherent n-type characteristics formed a pn heterojunction when grown on silicon. The heterojunction showed rectifying characteristics and excellent UV photoresponse.
关键词： electrical conductivity,nanowires,β-Ga2O3,oxidation,silver catalyst,photodetector
更新于2025-09-12 10:27:22
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Electrical property modified hole transport layer (PEDOT:PSS) enhance the efficiency of perovskite solar cells: hybrid co-solvent post-treatment
摘要： Poly(3,4-ethylenedioxythiphene):poly(styrenesulfonate) (PEDOT:PSS) layer as a hole transport layer (HTL) plays a key role in efficient hole extraction and transportation of the inverted planar perovskite solar cells (PSCs). However, the insulating nature of PSS lead to lower electrical property of the PEDOT:PSS film, which impedes transferring hole and results in a low photocurrent of the PSCs. In this work, dimethylformamide (DMF), methanol and their mixture solvents (co-solvent) were employed to treat the PEOT:PSS thin film after deposition with different methods to enhance the film’s electrical conductivity. Electrical conductivity of the PEDOT:PSS films was increased from 10-3 S.cm-1 to ~102 S.cm-1 after the co-solvents treatment. Using the highest conductivity co-solvent treated PEDOT:PSS thin film as the HTL in a perovskite solar cell, the power conversion efficiency (PCE) of the device has been measured improved by 17.5% as compared with that of the control device with the untreated PEDOT:PSS film as the HTL. This result shows that the hybrid co-solvent post-treatment is a simple and feasible way to modified the electrical properties of the PEDOT:PSS film as the HTL for high efficient PSCs and other thin film electronic and optoelectronic devices.
关键词： Perovskite solar cells,PEDOT:PSS,Hole transporting layer,Solvent treatment,Conductivity
更新于2025-09-12 10:27:22
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Intermingled Network of Syndiotactic Polystyrene/Poly(3-hexylthiophene)
摘要： By taking advantage of the fiber forming properties of both polymers in p-xylene, syndiotactic polystyrene (sPS) and poly(3-hexylthiophene) (P3HT) are mixed at an elevated temperature to prepare a composite network. These sPS?P3HT networks have been intensively investigated by UV?vis absorption, FTIR, and DSC; their morphologies by FE-SEM and FEG-TEM; and the molecular structure of the P3HT chains by neutron scattering experiments, rheology, and conductivity. Absorption measurements indicate the occurrence of π?π interaction between the P3HT chains and the sPS phenyl groups. Investigations by FESEM, TEM, and AFM show the formation of an intermingled network of sPS fibrils and P3HT ribbons. Small-angle neutron scattering studies reveal that a fraction of P3HT molecules is possibly encapsulated within the sPS fibrils. The increase of the elastic modulus with increasing P3HT content together with the increase of electrical conductivity is likely related to these encapsulated chains.
关键词： poly(3-hexylthiophene),composite network,syndiotactic polystyrene,π?π interaction,electrical conductivity
更新于2025-09-12 10:27:22
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Graphene’s photonics and optoelectronics properties – A Review
摘要： Due to its remarkable electrical and optical properties, graphene continues to receive more and more attention from researchers around the world. An excellent advantage of graphene is the possibility of controlling its charge density, and consequently, the management of its conductivity and dielectric constant, among other parameters. It is noteworthy that the control of these properties enables the obtaining of new optical/electronic devices, which would not exist, based on conventional materials. However, to work in this area of science, it is necessary a thorough knowledge regarding the electrical/optical properties of graphene. In this review paper, we show these graphene properties very well detailed.
关键词： Absorbance (78.20.-e),Conductivity (78.20.-e),Substrate (78.40.Fy),Reflectance (78.20.-e),Surface plasmons polaritons (73.20.Mf),Transmittance (78.20.-e),Dispersion relation (11.55.Fv),Dielecric constant (31.15.es)
更新于2025-09-12 10:27:22