共查询到20条相似文献,搜索用时 31 毫秒
1.
Irradiation-assisted processing, i.e. ion, electron and laser irradiation, have been applied to fabricate metal/glass nanocomposites. The particle configurations are studied by transmission electron microscopy to get some insight into the rather complex formation mechanisms. Special attention is given to spheroidally shaped particles surrounded by smaller secondary particles observed upon ion beam mixing of silica/silver/silica layer compounds as well as irradiating femtosecond laser pulses on sodium silicate glass containing spherical silver particles. Another unique type of structure are cavities observed in silver particles formed by high fluence ion implantation into silica as well as upon laser pulse irradiation of silver particles in glass. The experimental findings are discussed in terms of irradiation-induced defect formation and radiation-enhanced diffusion. 相似文献
2.
V. I. Egorov I. V. Zviagin D. A. Kliukin A. I. Sidorov 《Russian Journal of Physical Chemistry B, Focus on Physics》2017,11(1):87-88
We demonstrate a new method of silver nanoparticles formation on a silver-containing glass surface due to its irradiation by a pulsed CO2 and YAG:Nd lasers. The particles are formed as a result of reduction of silver ions from the glass at the edges of a laser torch emerging during evaporation and ablation. The settled particles are then fixed on sample surface by a shell of glass dielectric components. The method allows creating plasmonic nanostructures on the glass surface for sensing applications. 相似文献
3.
P.L. Taberna C. Portet P. Simon 《Applied Physics A: Materials Science & Processing》2006,82(4):639-646
Power improvement in supercapacitors is mainly related to lowering the internal impedance. The real part of the impedance
at a given frequency is called ESR (equivalent series resistance). Several contributions are included in the ESR: the electrolyte
resistance (including the separator), the active material resistance (with both ionic and electronic parts) and the active
material/current collector interface resistance. The first two contributions have been intensively described and studied by
many authors. The first part of this paper is focused on the use of surface treatments as a way to decrease the active material/current
collector impedance. Al current collector foils have been treated following a two-step procedure: electrochemical etching
and sol-gel coating by a highly-covering, conducting carbonaceous material. It aims to increase the Al foil/active material
surface contact leading to lower resistance. In a second part, carbon-carbon supercapacitor impedance is discussed in term
of complex capacitance and complex power from electrochemical impedance spectroscopy data. This representation permits extraction
of a relaxation time constant that provides important information on supercapacitor behaviour. The influence of carbon nanotubes
addition on electrochemical performance of carbon/carbon supercapacitors has also been studied by electrochemical impedance
spectroscopy.
PACS 82.45.Yz; 81.16.-c 相似文献
4.
Xavier Gerbaux Armand Hadni Masato Tazawa 《International Journal of Infrared and Millimeter Waves》1996,17(4):693-704
We have studied the Far Infrared transmission spectra of an MgO plate covered with an YBaCuO film of thickness t=200 Å, at different temperatures. By cooling from room temperature to temperatures < 140 K, the Far Infrared interference fringes are displaced by half a period. Explanation in terms of different adaptations of the YBaCuO sheet resistance to the MgO substrate impedance during cooling. 相似文献
5.
Muhammad Tariq Saeed Chani Kh. S. Karimov F. A. Khalid S. Z. Abbas M. B. Bhatty 《中国物理 B》2013,22(1):10701-010701
This study presents the fabrication and investigation of humidity sensors based on orange dye (OD) and polyaniline (PANI) composite films. A blend of 3 wt.% OD with 1 wt.% PANI was prepared in 1 ml water. The composite films were deposited on glass substrates between pre-deposited silver electrodes. The gap between the electrodes was 45 μm. The sensing mechanism was based on the impedance and capacitance variations due to the absorption/desorption of water vapor. It was observed that with the increase in relative humidity (RH) from 30% to 90%, the impedance decreases by 5.2 × 10 4 and 8.8 × 10 3 times for the frequencies of 120 Hz and 1 kHz, respectively. The impedance-humidity relationship showed a more uniform change compared to the capacitance-humidity relationship in the RH range of 30% to 90%. The consequence of annealing, measuring frequency, response and recovery time, and absorption-desorption behavior of the humidity sensor were also discussed in detail. The annealing resulted in an increase in sensitivity of up to 2.5 times, while the measured response time and recovery time were 34 s and 450 s, respectively. The impedance-humidity relationship was simulated. 相似文献
6.
Silver epoxy was selected to bond transducer plates on glass substrates. The properties and thickness of the bonding medium affect the electrical input impedance of the transducer. Thus, the thickness of the silver epoxy bonding layer was used as a design parameter to optimize the structure for the transducer input impedance to match the 50 Ω output impedance of most radio frequency (RF) generators. Simulation and experimental results show that nearly perfect matching is achieved without using any matching circuit. At the matching condition, the transducer operates at a frequency band a little bit below the half-wavelength resonant frequency of the piezoelectric plate. In experiments, lead titanate (PT) piezoelectric plates were employed. Both full-size, 11.5 mm × 2 mm × 0.4 mm, and half-size, 5.75 mm × 2 mm × 0.4 mm, can be well matched using optimal silver epoxy thickness. The transducer assemblies demonstrate high efficiency. The conversion loss from electrical power to acoustic power in soda-lime glass is 4.3 dB. This loss is low considering the fact that the transducers operate at off-resonance by 12%. With proper choice of silver epoxy thickness, the transducer can be matched at the fundamental, the 3rd and 5th harmonic frequencies. This leads to the possible realization of triple-band transducers. Reliability was assessed with thermal cycling test according to Telcordia GR-468-Core recommendation. Of the 30 transducer assemblies tested, none broke until 2900 cycles and 27 have sustained beyond 4050 cycles. 相似文献
7.
Yusuf Ziya Umul 《Optik》2012,123(19):1786-1791
The transmission and diffraction of waves by an aperture in an impedance screen is investigated. The Senior's solution of the scattering problem of waves by an impedance half-plane is transformed into a physical optics type integral. The obtained method is applied to the transmission problem of waves by a slit in an impedance screen. The results are compared with the aperture problem in black and conducting screens numerically. 相似文献
8.
《Physica B: Condensed Matter》2005,355(1-4):188-201
Complex impedance analysis of a new rare earth-based ceramic oxide, LaLiMo2O8, prepared by a standard solid-state reaction technique has been carried out. Material formation under the reported conditions has been confirmed by X- ray diffraction studies. A preliminary structural analysis indicates the crystal structure to be orthorhombic. Electrical properties of the material sample have been studied using AC impedance spectroscopy technique. Impedance spectrum results indicate that the electrical properties of the material are strongly dependent on temperature and it bears a good correlation with the sample microstructure (i.e. the presence of bulk, grain boundary, etc.) in different temperature ranges. Evidences of temperature-dependent electrical relaxation phenomena in the material have also been observed. The bulk resistance, evaluated from complex impedance spectrum has been observed to decrease with rise in temperature showing a typical negative temperature coefficient of resistance (NTCR)-type behavior like that of semiconductors. The DC conductivity shows typical Arrhenius behavior when observed as a function of temperature. The AC conductivity spectrum has provided typical signature of an ionically conducting system and is found to obey Jonscher's universal power law. Modulus analysis has indicated the possibility of hopping mechanism for electrical transport processes in the system with non-exponential-type conductivity relaxation. 相似文献
9.
Optical response of thin plasma-polymer films with non-spherical silver nanoparticles 总被引:1,自引:0,他引:1
A. Heilmann M. Quinten J. Werner 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(4):455-461
The size and shape of silver nanoparticles which are embedded in a plasma-polymer matrix were obtained by transmission electron
microscopy and analyzed with optical image processing. We used a sample in which silver particles were present before and
after reshaping caused by thermal annealing in adjacent regions. As most of the particles appeared as elongated rotational
ellipsoids, the major and minor half axis were determined for each particle. We adopted the model of Gans in the Rayleigh
approximation to calculate for each investigated particle the extinction spectra from to using the data from the image processing. The various spectra for 368 silver particles were added to get total extinction
spectra for the sample as deposited and after reshaping, respectively. We found good agreement with the experimental spectra.
The blue shift of the plasma-resonance absorption, which occurs due to the reshaping of the silver particles during thermal
annealing, was also confirmed by using only changes in the particle sizes and shapes.
Received: 23 July 1997 / Revised: 27 October 1997 / Accepted: 3 December 1997 相似文献
10.
11.
A. O. Rybaltovskii Yu. S. Zavorotnyi N. V. Minaev M. I. Samoilovich P. S. Timashev M. Yu. Tsvetkov V. N. Bagratashvili 《Russian Journal of Physical Chemistry B, Focus on Physics》2009,3(7):1106-1112
Silver-containing nanocomposites were prepared by impregnating Vycor glass (a pore diameter of 4 nm) and synthesized opal
matrices (an interstitial void size of 40 nm) with cyclooctadiene complex of silver hexafluoroacetylacetonate (Ag(hfac)COD),
a silver precursor, dissolved in supercritical carbon dioxide and were examined by optical absorption spectroscopy, atomic
force microscopy, and electron spin-resonance spectroscopy. It was demonstrated that the absorption spectra of Vycor glass
and opal matrices impregnated with Ag(hfac)COD molecules and subjected to thermal treatment in air at temperatures above 50°C
exhibit plasmon resonances characteristic of Ag nanoparticles at 420–430 nm. The peculiarities of the plasmon resonance band
for both types of samples were attributed to the morphology of the pore space in which silver particles are formed. Paramagnetic
Cu(hfac)2 molecules (copper hexafluoroacetylacetonate) were used as a spectroscopic probe for estimating the distribution of the precursor
in the pores of Vycor glass and opal matrices during supercritical fluid impregnation. 相似文献
12.
掺杂有Ⅱ-Ⅵ族半导体纳米颗粒(如CdS)或者过渡金属(如Ag)的玻璃由于其较大的非线性光学效应而引起人们的极大兴趣,而同时掺杂有半导体/金属的复合微粒则可以进一步增强玻璃的三阶非线性效应,因此成为目前的研究热点。我们利用玻璃沉淀技术及随后的热处理和紫外光还原技术制备了含高浓度(1%)Ag微粒的玻璃,并采用X射线衍射分析了其物相,用高分辨扫描电镜分析了其形貌,以及测试了其吸收和发光性能。从CdS/Ag复合微粒的扫描照片可以发现晶粒均匀分布在玻璃中,尺寸约为1μm。X射线衍射发现经过热处理和紫外光照的样品衍射峰中含有CdS和Ag,而只进行热处理的样品则只含有CdS,未处理的样品则显非晶态。CdS/Ag复合微粒的吸收峰呈现典型的表面等离子共振峰(420nm)以及CdS的峰(600nm),只含有CdS微粒的样品的吸收峰则在480nm附近,未处理的样品在320nm附近有一个吸收峰,这可能是由于样品在快速冷却过程中的微小晶化造成的。只含有CdS微粒的样品有三个明显的发光峰,然而CdS/Ag复合微粒的发过峰则消失。我们提出了共振能量转移机制来解释该现象。讨论了紫外光照还原Ag微粒的机制。可以认为通过紫外光照,CdS表面的电子被激发出来还原Ag+,从而形成银颗粒,伴随着空穴则被表面缺陷所捕获。 相似文献
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14.
Ya Chen Janne J. Jaakola Antti Syntjoki Ari Tervonen Seppo Honkanen 《Journal of Raman spectroscopy : JRS》2011,42(5):936-940
Glass‐embedded silver nanoparticle patterns were fabricated by masked silver–sodium ion‐exchange process followed by etching to reveal the particles for surface‐enhanced Raman scattering (SERS). The intensity of the enhanced Raman signal is comparable to that of the fluorescence, and the detection limit of 1 nM for Rhodamine 6G has been achieved. Raman images at different etching depths and corresponding morphological images are compared to find optimal SERS signal. Our results demonstrate that silver nanoparticle patterns embedded in glass can be used as SERS‐active substrates. Nanoparticles can be formed in a glass of high optical quality and have potential to be integrated with optical waveguides for a sensor chip. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
15.
Multi-layered thin films, which consisted of metallic silver, GeSe3 glass, and silver oxyhalide superionic conductor glass were prepared. Photo- and electrochemical reaction of metallic silver with the chalcogenide glass layer was studied by optical absorbance and cyclic-voltammetry. Photo-doping of silver through the superionic glass layer was observed using evaporated AgI---Ag2MoO4 film and it was partly undoped by electrochemical treatment. However, no photo-doping was observed for the cell consisting of a AgI---AgPO3 dip-coated layer. The doped silver was dissolved into the GeSe3 layer during the photo-doping process. However, it formed another intermediate compound layer (probably silver selenide) during the electrodoping process. 相似文献
16.
The ac-impedance of compressed powders of the ion conducting zeolites chabazite and 13X has been measured. The porosity of the samples was changed by applying an external pressure. The impedance diagrams were suppressed semicircles. The impedance as well as the suppression angle decreased with increasing relative density. This shows that the particle-particle contact gives a significant contribution to the overall impedance. The frequency dependency of the current constriction at contact points between particles is described by a simplified equivalent network. The analytical expression is analogous to an equation for the impedance of fractal interphases leading to a constant phase angle element in the equivalent diagram. 相似文献
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18.
Homogeneous interface-type resistance switching in Au/La<sub>0.67</sub>Ca<sub>0.33</sub>MnO<sub>3</sub>/SrTiO<sub>3</sub>/F:SnO<sub>2</sub> heterojunction memories
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La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer. The current-voltage characteristics of the heterojunctions exhibit an asymmetric and resistance switching behaviour. A homogeneous interface-type conduction mechanism is also reported using impedance spectroscopy. The spatial homogeneity of the charge carrier distribution leads to field- induced potential-barrier change at the Au-La0.67Ca0.33MnO3 interface and a concomitant resistance switching effect. The ratio of the high resistance state to the low resistance state is found to be as high as 1.3 × 10 4 % by simulating the AC electric field. This colossal resistance switching effect will greatly improve the signal-to-noise ratio in nonvolatile memory applications. 相似文献
19.
Maohua Li Ruiqi Lv Shengchao Huang Yinzhen Dai Zhicong Zeng Lei Wang Bin Ren 《Journal of Raman spectroscopy : JRS》2016,47(7):808-812
Both tip‐enhanced Raman spectroscopy and scanning tunneling microscopy require the use of sharp tips. Electrochemical etching appears to be the most widely used method for preparing tips. To address the over‐etching problem associated with the silver tips by either using voltage or current as a feedback, we developed here an optical method‐based machine vision to achieve a quick cutoff of the circuit once the tip forms. It is a fully automated method with a response time of about 40 ms and is tolerated with any existing electrochemical etching method. We can significantly decrease the time of over‐etching of the silver tip when short rectangular pulses with a duty cycle of 28.6% were used. The mean radius of curvature was ca. 58 nm, as measured from over 50 tips. The capacities of silver tips for high‐resolution scanning tunneling microscopy imaging and high‐sensitivity tip‐enhanced Raman studies have been demonstrated. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
20.
Four-point impedance spectroscopy of solid materials systems is severely hampered by unavoidable voltage-divider effects associated with the reference electrodes. As demonstrated by test circuit studies and experiments with Pt/YSZ/Pt cells (with embedded silver reference electrodes), high impedance reference electrodes can produce distorted and erroneous impedance data. The relationships between these data and the sample properties (conductivity, dielectric constant) and instrument limitations (input impedance/capacitance) are derived. Successful four-point impedance measurements on conductive systems require large effective dielectric constants, which may be unattainable in bulk solids, but are often associated with internal interfaces. 相似文献