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The Electrical Property of Large Few Layer Graphene Flakes Obtained by Microwaves Assisted Exfoliation of Expanded Graphite
摘要： Few layer graphene (FLG) was synthesized by (cid:2)-wave assisted exfoliation of expanded graphite in toluene with an overall yield from c.a. 7% to 20%. A significant difference in the absorption of (cid:2)-waves by the expanded graphite and toluene allowed a rapid heating of the medium. The number of FLG sheets varies from 3 to 12, while the lateral size of the sheets exceeds few (cid:2)ms. The obtained FLG exhibits very low resistance with average value of 1.6 k(cid:3) (500 (cid:3) minimum) which is comparable to that of high quality graphenes synthesized by CVD methods, and lower than numbers of exfoliated graphenes.
关键词： (cid:2)-waves,electrical properties,expanded graphite,few layer graphene,resistance.,liquid exfoliation
更新于2025-09-11 14:12:44
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Substrate temperature-dependent properties of sprayed cobalt oxide thin films
摘要： Cobalt oxide (Co3O4) thin films were deposited onto amorphous glass substrates using a home-made pneumatic spray pyrolysis system (SPT) from aqueous solution of cobalt chloride salt (CoCl2) as a source of cobalt. The films were deposited at different substrate temperatures ranging from 250 to 450?°C in steps of 50?°C. The effect of substrate temperature on structural, electrical and optical properties was studied. The characterization of samples was carried out by X-ray diffraction (XRD), UV–Vis spectroscopy, energy dispersive spectroscopy (EDS), scanning electron microscopy and four probe points measurements. The XRD study showed that all the films were polycrystalline consisting of Co3O4 spinel cubic phase. The preferred orientation of the crystallites changed from (311) to (111) when the substrate temperature increases. The average calculated grain size was about 40.38?nm. Morphological studies exposed that the films surface morphology is almost homogeneous and well-covered. Peaks associated with Co and O elements are present in EDS analysis witch confirm the composition of the films. The optical transmittance and the band gaps energy increase with the increase of substrate temperature. The measured electrical conductivity at room temperature was found in the order of 10?1 (??cm)?1.
关键词： Thin films,Substrate temperature,Cobalt oxide,Spray pyrolysis,Structural properties,Optical properties,Electrical properties
更新于2025-09-10 09:29:36
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Investigation of thermal and electrical properties of As–Se glasses modified with Cu using DSC and AC impedance spectroscopy
摘要： Investigations of thermal properties of CuxAs50Se50 ? x chalcogenides were carried out using a differential scanning calorimeter. It was established that copper introduction significantly affects the complexity of structural network. This was indicated by double-stage crystallization process in the compound Cu15As50Se35. Besides α relaxation, all the glasses during heating show β relaxation. The complexity of the network influences the conductivity values and transport properties in a way of higher DC and AC conductivity for the compound with the highest Cu share. Impedance spectra show two semicircles, indicating the existence of two polarization processes in different frequency ranges. The presence of kinetic and as well as diffusion processes in polarization of the samples with x = 10 and 15 at% of Cu strongly affects the unusually high values of the real part of dielectric permittivity in low- and medium-frequency range.
关键词： AC impedance spectroscopy,electrical properties,thermal properties,Cu modification,DSC,As–Se glasses
更新于2025-09-10 09:29:36
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Influences of reaction temperature, holding time and S/Zn molar ratio on structure, morphology, optical and electrical properties of ZnS nanoparticles synthesized by hydrothermal method
摘要： ZnS nanoparticles were synthesized by hydrothermal method. The influences of reaction temperature, holding time and S/Zn molar ratio on the structure, morphology, optical and electrical properties of ZnS nanoparticles were studied systematically at the range of 90?°C to 180?°C, 6?h to 15?h and 1:2 to 2.5:1, respectively. The results indicate that the reaction temperature, holding time and S/Zn molar ratio have no influence on phase structure. All the samples belong to zinc blende cubic structure of ZnS. However, the reaction temperature has strong influences on the growth of crystals, optical and electrical properties due to LaMer theory and two-stage growth kinetics. When the reaction temperature increases from 90?°C to 180?°C, the crystallite sizes increase from 7.0?nm to 9.7?nm and the average particle sizes decrease from 21?nm to 14?nm; the emission peaks are red shifted from 445?nm to 460?nm and the emission intensity is increased by 4.4 times; the dielectric constant and dielectric loss decrease from 4.86 to 4.71 and 2.86 × 104 to 2.70 × 104, respectively. While, the holding time has slight influences on the growth of crystals, optical and electrical properties. And the emission band and emission intensity of ZnS nanoparticles can be adjusted by the S/Zn molar ratio. When the S/Zn molar ratio is less than 1:1 or equal to 1:1, the emission bands range from 400?nm to 600?nm centered at ~ 450?nm. When the S/Zn molar ratio is greater than 1:1, the emission bands range from 400?nm to 700?nm centered at ~ 540?nm.
关键词： Holding time,Optical properties,Reaction temperature,Hydrothermal method,S/Zn molar ratio,ZnS nanoparticles,Electrical properties
更新于2025-09-10 09:29:36
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Electrical and optical properties of metal-sandwiched ZnO/Ti/Cu/Ti/ZnO transparent conductive thin film
摘要： Metal-sandwiched zinc oxide (ZnO)/titanium (Ti)/copper (Cu)/Ti/ZnO thin film systems were fabricated using magnetron sputtering technology and then annealed using a rapid thermal annealing system at temperatures from 100 to 400°C. The influence of the Ti film thicknesses and annealing temperatures on the surface morphologies, sheet resistance and optical properties were studied. The surface morphologies change a little with the annealing temperature rises. The sheet resistances reduce with the Ti film thickness or annealing temperature increasing. Both the max transmittance and figure of merit reduce with the increase of Ti film thickness. The max transmittance increases with the temperature increasing from 100 to 300°C and then reduces. However, the figure of merit increases with the temperature increasing which indicates that the metal-sandwiched ZnO/Ti/Cu/Ti/ZnO thin film system annealed at 400°C has the optimal performance.
关键词： ZnO,optical properties,annealing,magnetron sputtering,Cu,electrical properties,transparent conductive thin film,Ti
更新于2025-09-10 09:29:36
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V2O5 Thin Films as Nitrogen Dioxide Sensors ?
摘要： Vanadium pentoxide thin films were deposited onto insulating support by means of rf reactive sputtering from a metallic vanadium target. Argon-oxygen gas mixtures of different compositions controlled by the flow rates were used for sputtering. X-ray diffraction at glancing incidence (GIXD) and Scanning Electronic Microscopy (SEM) were used for structural and phase characterization. Thickness of the films was determined by the profilometry. It has been confirmed by GIXD that the deposited films are composed of V2O5 phase. The gas sensing properties of V2O5 thin films were investigated at temperatures from range 410–617 K upon NO2 gas of 4–20 ppm. The investigated material exhibited good response and reversibility towards nitrogen dioxide. The effect of metal-insulator transition (MIT) on sensor performance has been observed and discussed for the first time. It was found that a considerable increase of the sensor sensitivity occured above 545 K, which is related to postulated metal-insulator transition.
关键词： reactive sputtering,vanadium pentoxide,metal-insulator transition (MIT),electrical properties,thin film,gas sensor,nitrogen dioxide
更新于2025-09-10 09:29:36
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Strategies to facilitate the formation of free standing MoS <sub/>2</sub> nanolayers on SiO <sub/>2</sub> surface by atomic layer deposition: A DFT study
摘要： In this study, we employ density functional theory calculations to investigate the very initial formation of a buffer layer during atomic layer deposition of MoS2 at the SiO2 (001) surface. In our previous study, we described that the self-limiting atomic layer deposition (ALD) reactions using Mo(NMe2)2(NtBu)2 as precursor and H2S as co-reagent terminate in the formation of a so-called building block on the SiO2 (001) surface. This building block consists of Mo which shares bonds with the surface O of SiO2 (001) at the bottom and terminal S at the top. Electronic band structure calculations indicate that the subsequently deposited buffer-layer that is composed of these building blocks has (opto)-electrical properties that are far from the ideal situation. Based on our studies, we propose alternative ALD chemistries which lead to the formation of a so-called underpinned building block. In this cluster, the Mo atoms are underpinned by S atoms, suppressing the formation of a buffer layer. This ultimately facilitates the formation of a free standing conformal 2D-MoS2 nanolayer at the interface. Through the proposed chemistries, the opto-electrical properties of the deposited layers will be preserved.
关键词： opto-electrical properties,MoS2,SiO2,density functional theory,atomic layer deposition
更新于2025-09-10 09:29:36
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[IEEE 2018 EMF-Med 1st World Conference on Biomedical Applications of Electromagnetic Fields (EMF-Med) - Split, Croatia (2018.9.10-2018.9.13)] 2018 EMF-Med 1st World Conference on Biomedical Applications of Electromagnetic Fields (EMF-Med) - In Vivo Electrical Conductivity Imaging of Animal Tumor Model at 7T using Electrical Properties Tomography
摘要： Ex vivo studies have shown that various diseases alter the electrical properties of tissues compared to healthy nearby tissues. Therefore, electrical conductivity can be used as a diagnostic parameter for e.g. tumor diagnosis. For in vivo measurements, magnetic resonance electrical properties tomography (MREPT) was used and electrical conductivity was reconstructed from the B1+ phase. The technique was first evaluated using homogeneous and heterogeneous phantoms. Then a mouse with a tumor was scanned and the conductivity is reconstructed from the B1+ phase map. The reconstructed conductivity in the phantom experiments was in good agreement with the target conductivity map and the conductivity map of the animal revealed good agreement with the co-axial probe measurement. Our work confirms the possibility of accurate in vivo conductivity assessment in disease.
关键词： tumor imaging,conductivity,MRI,EPT,Electrical properties tomography
更新于2025-09-10 09:29:36
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Improvement of electrochemical and structural properties of polycarbazole by simultaneous electrodeposition of chitosan
摘要： Polycarbazole/chitosan composite materials were synthesized electrochemically at various loadings of chitosan (Chi). Their electrochemical, structural, thermal, and morphological characterizations were investigated by cyclic voltammetry, chronoamperometry, electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy, thermal gravimetry, and scanning electron microscopy. Further electrical conductivity was measured using a four-point probe technique. The electrochemical results showed that the electrical conductivity of the polymeric composite (cid:12)lm was increased by increasing the amount of Chi in the electrolyte medium. The as-prepared composite (cid:12)lms exhibited enhanced electrical conductivity and structural properties of polycarbazole due to the presence of Chi in the composite (cid:12)lms.
关键词： chitosan,electropolymerization,electrical properties,Polycarbazole,conducting composite
更新于2025-09-10 09:29:36
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Amorphous InZnO:Li/ZnSnO:Li dual-active-layer thin film transistors
摘要： Amorphous Li-doped InZnO and ZnSnO (IZO:Li/ZTO:Li) dual-active-layer thin film transistors (TFTs) were fabricated by radio-frequency (RF) magnetron sputtering. The transmittance of the dual-stacked IZO:Li/ZTO:Li thin film was over 85% in the visible range. X-ray diffraction (XRD) result indicated that the thin film was amorphous. The influence of ZTO:Li layer thickness on the electrical characteristics and bias-stress stability of the dual-active-layer TFT was investigated. With the increasing thickness of ZTO:Li thin film, the saturation mobility (μSAT) increased firstly and then decreased, while the threshold voltage (VTH) shifted to the positive direction. The TFT with the optimized ZTO:Li thickness showed a superior performance with a μSAT of 33.2 cm2/V·s, a VTH of 3.2 V, a sub-threshold swing (SS) of 0.6 V/decade and a current on/off (ION/IOFF) up to 3.2 × 108.
关键词： B. Sputtering,A. Semiconductors,D. Electrical properties,A. Thin films,A. Amorphous materials
更新于2025-09-10 09:29:36