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1.
In this study, the electrical, optical and mechanical properties of polystyrene (PS) thin films added graphene nanoplatelet (GNP) have been investigated. Surface conductivity ( σ), absorbance intensity ( A) and tensile modulus of these composite films have increased with increasing the content of GNP in the composite. The increase in the electrical and optical properties of the PS/GNP composite films has been interpreted by site and classical percolation theory, respectively. The electrical and the optical percolation thresholds of PS/GNP composite films were determined as Rσ?=?23.0?wt.% and Rop?=?13.0?wt.%, respectively. While the conductivity results have been attributed to the classical percolation theory, the optical results have attributed to the site percolation theory. The electrical ( βσ) and the optical ( βop) critical exponents were calculated as 2.54 and 0.40, respectively. The tensile modulus and the tensile strength of the PS/GNP composites increased with the increasing of GNP content in the PS. But, the toughness of the composites fluctuated with GNP addition. 相似文献
2.
Effects of multiwall carbon nanotube (MWCNT) addition on the electrical conductivities, optical transparencies and fluorescence emissions of poly(vinyl acetate-co-butyl acrylate) (P(VAc-co-BuA))/MWCNT composite films were studied. Optical transmission, fluorescence emission and two point probe resistivity techniques were used to determine the variations of the optical, fluorescence and electrical properties of the composites, respectively. Transmitted photon intensity ( I tr), fluorescence emission intensity ( I fl) and surface resistivity ( ρ s) of the composite films were monitored as a function of MWCNT mass fraction ( M) at room temperature. All these measured quantities of the composites were decreased by increasing the content of MWCNT in the composite. The conductivity and the optical results were attributed to the classical and site percolation theories, respectively. The fluorescence results, however, possessed both the site and classical percolation theories at low and high MWCNT content regions, respectively. 相似文献
3.
This study investigated the use of graphene nanoplatelets (GNP) as a conductive filler for electrostatic discharge (ESD) protective packaging. Various weight concentrations of GNP were mixed and sonicated with polyvinyl alcohol (PVOH). The resulting polymer solution was applied as a coating to corrugated board in order to form an ESD packaging. Surface resistivity, mechanical strength and coating adhesion were then measured. The study found that the electrical percolation threshold of the PVOH/GNP coating is 9–13wt% GNP. GNP incorporated PVOH coatings with surface resistivity of 10 3–10 8 Ω/sq. generally meet all of ESD packaging requirements. The humidity strongly affects the surface resistivity of the coatings below the percolation threshold, but the change of the surface resistivity with humidity is less significant above the percolation threshold. 相似文献
4.
ABSTRACTLa 0.7Ca 0.3MnO 3 perovskite and its composites with graphene nanoplatelet (GNP) were prepared using a wet chemical method. The structural, magnetic and magnetocaloric properties of La 0.7Ca 0.3MnO 3: GNP composites were investigated to determine the effect of GNPs. The results of XRD analysis show that the synthesised powders can be almost indexed to pure phase orthorhombic La 0.7Ca 0.3MnO 3. The magnetic measurements demonstrate that 0.7 and 1% GNP amounts cause an increase in the Curie temperature ( TC), and for larger amounts of GNP, the TC monotonically decreases, except for the sample with 10% GNP. The results obtained from the Arrott plots show that the magnetic phase transition of the samples transforms from the first to second order with increasing GNP amount. The changes in the magnetocaloric properties are interpreted in terms of perovskite phase formations via structural analysis. The amounts of graphene nanoplatelets in the oxide powders are correlated with the observed magnetocaloric properties. The best magnetocaloric performance with the maximum magnetic entropy change of 3.99 Jkg ?1K ?1 and refrigeration capacity of 90 Jkg ?1 was obtained at a 2?T magnetic field. 相似文献
5.
The phase transitions in smectogenic liquid crystal BBBA (4-butoxybenzylidene-4′-butylaniline) doped by multi-walled carbon nanotubes (NTs) were studied by methods of optical transmission, differential scanning calorimetry (DSC), measurement of electrical conductivity and analysis of microscopic images. The concentration of NTs was varied within 0–1% wt. Non-monotonous (extremal) changes in temperature, enthalpies and half-width of the DSC peaks of transitions between different phases (smectics, nematic, isotropic) were observed for NT concentrations between 0.05 and 0.1% wt. A noticeable increase of electrical conductivity σ in the same concentration interval evidenced the presence of percolation transition and formation of conductive NT networks. The detailed analysis of σ behavior in the whole concentration interval 0–1% wt revealed the presence of a fuzzy type percolation with multiple thresholds in the studied BBBA?+?NT suspensions. The percolation behavior was strongly dependent on the temperature, and a noticeable step-like drop of σ in the vicinity of isotropic-nematic transition was observed after the multiple heating–cooling cycles. 相似文献
7.
The ferromagnetic transparent conducting film is a multifunctional film which has high visible transmittance, low resistivity
and room-temperature ferromagnetism, simultaneously. In this article, ferromagnetic transparent conducting ZnO:Al/Fe 65Co 35/ZnO:Al multilayer films were fabricated by inserting a middle magnetic Fe 65Co 35 layer into aluminum-doped zinc oxide (ZnO:Al) matrix using a magnetron sputtering apparatus at substrate temperature ranging
from room temperature ( RT) to 400 ∘C. The total film thickness was about 400 nm and the middle Fe 65Co 35 alloy layer was 4 nm. The influences of substrate temperature ( T
s
) on the structural, electrical, optical and magnetic properties of the multilayer films were systemically investigated. The
results showed that the microstructure and performance of the composite multilayer films strongly depended on the substrate
temperature. The present results also showed that the inserted middle Fe 65Co 35 alloy thin layer played an important role in providing the RT ferromagnetism and decreasing the resistivity of the multilayer films. Therefore, it is possible to obtain a multifunctional
film material with the combination of good optical transparency, high electrical conductivity and RT ferromagnetism. 相似文献
8.
In this work, graphene oxide–cuprous oxide (GO–Cu 2O) composite films were grown on fluorine-doped tin oxide substrates by electrochemical deposition. We investigated the effects of the annealing temperature on the morphological, structural, optical and photoelectrochemical (PEC) properties of GO–Cu 2O composite films. As a result, our work shows that while GO–Cu 2O composite films exhibit the highest XRD (111) peak intensity at 300 °C sample, the highest photocurrent density value obtained was −4.75 mA/cm 2 at 200 °C sample (using 0.17 V versus a reversible hydrogen electrode (RHE)). In addition, a reduction reaction at 300 °C sample was observed using XPS analysis from the shift in the O1s peak in addition to a weaker O1s peak intensity. 相似文献
9.
Poly(azomethine sulfone)s were synthesized by reacting 4,4′-sulfonyl bis(4-chlorophenyl) with 2,2-bis(4-hydroxyphenyl)propane and azomethine bisphenol in different molar ratios. Thin films were deposited from solution onto glass substrates. Study of the temperature dependences of the electrical conductivity, σ, and Seebeck coefficient, S, were performed in the temperature range 300 K–500 K. Thermal activation energies of electrical conduction, Ea , calculated from these dependences, ranged between 1.50 eV and 1.85 eV. The values of Ea were smaller for polymers with extended conjugation systems. The possibility to use the polymers in thermistor technology is discussed. The aspect of the temperature dependences of σ and S shows that a model based on the energy band-gap representation can be successfully used for explaining the electronic transport mechanism in the higher temperature range. In the lower temperature range, the mechanism of the electrical conduction is discussed in terms of the Mott variable range hopping conduction. The values of some optical parameters (absorption coefficient, optical band gap, etc.) were determined from transmission spectra. 相似文献
10.
在异质结前界面缺陷态密度Dit1和异质结背界面缺陷态密度Dit2均取不同值时,对p型单晶硅(c-Si(p))为衬底的硅异质结太阳电池的衬底电阻率ρ与电池性能的关系进行了数值研究.结果表明:衬底电阻率的最优值ρop取决于前界面缺陷态密度Dit1,且ρop随着Dit1的增大而增大;当ρρop时,背界面缺陷态密度Dit2对衬底电阻率的可取值范围具有较大影响,Dit2越大衬底电阻率的可取值范围越小. 相似文献
11.
In order to investigate the effect of thermal oxidation temperature on tin dioxide (SnO 2), tin dioxide films were obtained on quartz substrates by vacuum evaporation of tin metal. The films were characterized by X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), temperature dependent electrical resistivity measurement and optical absorption spectroscopy. The SEM images showed that the films are dense, continuous and are composed of nanoparticles and particle sizes are increased after thermal oxidation. From the X-ray measurement results, the films indicated two strong reflection peaks of tetragonal structure in the orientations of (1 0 1) and (2 0 0) at 2 θ = 33.89° and 37.95°, respectively. Intensity of the peaks increased with increasing thermal oxidation temperature. We found resistivity values of about 10 −4 Ω-cm. Optical absorption spectra of the films in the UV–Vis spectral range revealed that optical band gap ( Eg) value of the films increases with increasing thermal oxidation temperature. 相似文献
12.
Indium-tin-oxide (ITO) and indium-tin-oxynitride (ITON) films have been deposited on glass by rf-sputtering from an ITO target, using Ar plasma and N 2 plasma, respectively, and different rf-power. Optical emission spectroscopy (OES) was employed to identify the species present in the plasma and to correlate them with the properties of the ITO and ITON thin films. Emission lines of ionic In could only be detected in N 2 plasma, whereas in the Ar plasma additional lines corresponding to atomic In and InO, were detected. The deposition rate of thin films was correlated with the In species, rather than the nitrogen species, emission intensity in the plasma. The higher resistivity and lower carrier concentration of the ITON films, as compared to the respective properties of the ITO films, were attributed to the incorporation of nitrogen, instead of oxygen, in the ITON structure. 相似文献
13.
Optical and electrical properties of diamond-like carbon (DLC) films deposited by pulsed laser ablation of graphite target at different substrate temperatures are reported. By varying the deposition temperature from 400 to 25℃, the film optical transparency and electrical resistivity increase severely. Most importantly, the transparency and resistivity properties of the DLC films can be tailored to approaching diamond by adjusting the deposition temperature, which is critical to many applications. DLC films deposited at low temperatures show excellent optical transmittance and high resistivity. Over the same temperature regime an increase of the spa bonded C content is observed using visible Raman spectroscopy, which is responsible for the enhanced transparency and resistivity properties. 相似文献
14.
Monoclinic bismuth oxide (Bi 2O 3) films have been prepared by thermal oxidation of vacuum evaporated bismuth thin films onto the glass substrates. In order to obtain the single phase Bi 2O 3, the oxidation temperature was varied in the range of 423-573 K by an interval of 50 K. The as-deposited bismuth and oxidized Bi 2O 3 films were characterized for their structural, surface morphological, optical and electrical properties by means of X-ray diffraction, scanning electron microscopy (SEM), optical absorption and electrical resistivity measurements, respectively. The X-ray analyses revealed the formation of polycrystalline mixed phases of Bi 2O 3 (monoclinic, α-Bi 2O 3 and tetragonal, β-Bi 2O 3) at oxidation temperatures up to 523 K, while at an oxidation temperature of 573 K, a single-phase monoclinic α-Bi 2O 3 was formed. From SEM images, it was observed that of as-deposited Bi films consisted of the well-defined isolated crystals of different shapes while after thermal oxidation the smaller dispersed grains were found to be merged to form bigger grains. The changes in the optical properties of Bi 2O 3 films obtained by thermal oxidation at various temperatures were studied from optical absorption spectra. The electrical resistivity measurement depicted semiconducting nature of Bi 2O 3 with high electrical resistivity at room temperature. 相似文献
15.
Results of the study of structural and optical properties of Cu2ZnSn(S,Se)4 thin films obtained by sulfitation (selenization) of Cu2ZnSn films which were sputtered by target direct current magnetron sputtering using a stoichiometric Cu2ZnSn (99.99%) target are presented. It has been found that Cu2ZnSn(S,Se)4 thin films are polycrystalline with a grain size of ~60 nm. The optical bandgap of Cu2ZnSnS4 (E
op
g
= 1.65 eV) and Cu2ZnSnSe4 (R
op
g
= 1.2 eV) thin films have been determined. 相似文献
16.
Cd 1?xZn xO thin films were prepared by spray pyrolysis in air atmosphere on a glass substrate at 250 °C. The Zn content in Cd 1?xZn xO films was varied from x = 0 to 0.60. Structural, electrical and optical properties of Cd 1?xZn xO films were investigated by x‐ray diffraction, electrical resistivity and optical transmittance spectra, respectively. As the Zn content in Cd 1?xZn xO thin films increased, the preferred orientation of the films did not change, only the peak intensity of the planes decreased. In addition to the peaks of CdO, peaks of ZnO were observed in the film with x = 0.6. The resistivity of Cd 1?xZn xO thin films increased with increasing Zn content. Transmittance spectra studies of films were carried out in the 190‐1100 nm wavelength range and the results showed that the bandgap energy range varied from 2.42 to 3.25 eV. In addition, alloying effect on the Kβ/Kα intensity ratio in Cd 1?xZn xO semiconductor thin films was studied. It was found that the Kβ/Kα intensity ratio is changed by alloying effects in Cd 1?xZn xO semiconductor thin films for different composition of x. The results were compared with the theoretical values. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
17.
The optical properties of ethylene vinyl acetate (EVA) film have been studied. The effects of gamma irradiations on the optical spectrum of EVA films have been investigated using spectrophotometric measurements of reflectance and transmittance in the wavelength range 200–1100 nm. The absorption spectra were recorded in the UV–vis region for the unirradiated and irradiated films (from 0 to 50 kGy). Optical constants such as refractive index ( n), extinction coefficient ( K), and complex dielectric constant have been determined, as well as the optical dispersion parameters and high frequency dielectric constants. A large dependence of the fundamental optical constants on the irradiation dose was noticed. On irradiation, a higher refractive index was obtained as compared with that for unirradiated film. The dispersion parameters, such as E 0 (single‐oscillator energy), E d (dispersive energy), and M ?1 and M ?3 (moments), are discussed in terms of the single‐oscillator Wemple–DiDomenico model. 相似文献
18.
Aluminium-doped (Al = 0–5?wt.%) SnO 2 thin films with low-electrical resistivity and high optical transparency have been successfully synthesized by pulsed laser deposition technique at 500 °C. Structural, optical and electrical properties of the as-deposited and post-annealed thin films were investigated. X-ray diffraction patterns suggest that the films transform from crystalline to amorphous state with increasing aluminium content. The root mean square ( Rq) surface roughness parameter, determined by atomic force microscopy decreases upon annealing of the as-deposited film. While resistivity of the film is the lowest (9.49 × 10 ?4 Ω-cm) at a critical doping level of 1?wt.% Al, optical transparency is the highest (nearly 90%) in the as-deposited condition. Temperature dependence of the electrical resistivity suggests that the Mott’s variable range hopping process is the dominant carrier transport mechanism in the lower temperature range (40–135 K) for all the films whereas, thermally activated band conduction mechanism seems to account for conduction in the higher temperature region (200–300 K). 相似文献
19.
The electrical conductivity of amorphous polymer/multiwall carbon nanotube (MWCNT) composite films strongly depends on the Bernard-Marangoni (B-M) instability during solvent evaporation. We demonstrate that the films exhibit the lowest surface resistivity and the highest light transmittance near the onset point of B-M instability. The polymer/MWCNT composite films exhibit three-dimensional behavior in spite of the B-M instability. The percolation threshold for PC/MWCNT composite films at stable, onset, and unstable condition is 3.3 × 10 −3, 2.75 × 10 −3, and 5.15 × 10 −3 vol.%, respectively. 相似文献
20.
Uniform and adherent cobalt oxide thin films have been deposited on glass substrates from aqueous cobalt chloride solution, using the solution spray pyrolysis technique. Their structural, optical and electrical properties were investigated by means of X-ray diffraction (XRD), scanning electron micrograph (SEM), optical absorption and electrical resistivity measurements. Along with this, to propose Co 3O 4 for possible application in energy storage devices, its electrochemical supercapacitor properties have been studied in aqueous KOH electrolyte. The structural analysis from XRD pattern showed the oriented growth of Co 3O 4 of cubic structure. The surface morphological studies from scanning electron micrographs revealed the nanocrystalline grains alongwith some overgrown clusters of cobalt oxide. The optical studies showed direct and indirect band gaps of 2.10 and 1.60 eV, respectively. The electrical resistivity measurement of cobalt oxide films depicted a semiconducting behavior with the room temperature electrical resistivity of the order of 1.5 × 10 3 Ω cm. The supercapacitor properties depicted that spray-deposited Co 3O 4 film is capable of exhibiting specific capacitance of 74 F/g. 相似文献
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